US life expectancy on the rise for 1st time in 4 years @ Article: Human population: the next half century. Science. 2003 Nov 14;302(5648):1172-5. @ Inside a Google data center @ Facebook’s largest Data Center you never seen @ The Structure of DNA @ Data Science In 5 Minutes | Data Science For Beginners | What Is Data Science? | Simplilearn @ Most Popular Websites 1996 – 2019 @ The Most Popular Database (TOPDB Index) 2004 – 2019 @ Google Data Center 360° Tour @ Facebook Data Center @ ´´Innovation in its modern meaning is “a new idea, creative thoughts, new imaginations in form of device or method”.[1] Innovation is often also viewed as the application of better solutions that meet new requirements, unarticulated needs, or existing market needs.[2]´´ #@ Bill Gates warned in 2018 that new disease could kill 30M people in 6 months @ Here’s what coronavirus does to the body – From blood storms to honeycomb lungs, here’s an organ-by-organ look at how COVID-19 harms humans. &@Links, videos and images

Do the downloads!! Share!! The diffusion of very important information and knowledge is essential for the world progress always!! Thanks!!

  • – > Mestrado – Dissertation – Tabelas, Figuras e Gráficos – Tables, Figures and Graphics´´My´´ Dissertation @ #Innovation #energy #life #health #Countries #Time #Researches #Reference #Graphics #Ages #Age #Mice #People #Person #Mouse #Genetics #PersonalizedMedicine #Diagnosis #Prognosis #Treatment #Disease #UnknownDiseases #Future #VeryEfficientDrugs #VeryEfficientVaccines #VeryEfficientTherapeuticalSubstances #Tests #Laboratories #Investments #Details #HumanLongevity #DNA #Cell #Memory #Physiology #Nanomedicine #Nanotechnology #Biochemistry #NewMedicalDevices #GeneticEngineering #Internet #History #Science #World

Pathol Res Pract. 2012 Jul 15;208(7):377-81. doi: 10.1016/j.prp.2012.04.006. Epub 2012 Jun 8.

The influence of physical activity in the progression of experimental lung cancer in mice

Renato Batista Paceli 1Rodrigo Nunes CalCarlos Henrique Ferreira dos SantosJosé Antonio CordeiroCassiano Merussi NeivaKazuo Kawano NagaminePatrícia Maluf Cury


GRUPO_AF1GROUP AFA1 – Aerobic Physical Activity – Atividade Física Aeróbia – ´´My´´ Dissertation – Faculty of Medicine of Sao Jose do Rio Preto

GRUPO AFAN 1GROUP AFAN1 – Anaerobic Physical ActivityAtividade Física Anaeróbia – ´´My´´ Dissertation – Faculty of Medicine of Sao Jose do Rio Preto

GRUPO_AF2GROUP AFA2 – Aerobic Physical ActivityAtividade Física Aeróbia – ´´My´´ Dissertation – Faculty of Medicine of Sao Jose do Rio Preto

GRUPO AFAN 2GROUP AFAN 2 – Anaerobic Physical ActivityAtividade Física Anaeróbia´´My´´ Dissertation – Faculty of Medicine of Sao Jose do Rio Preto

Slides – mestrado´´My´´ Dissertation – Faculty of Medicine of Sao Jose do Rio Preto



Avaliação da influência da atividade física aeróbia e anaeróbia na progressão do câncer de pulmão experimental – Summary – Resumo´´My´´ Dissertation Faculty of Medicine of Sao Jose do Rio Preto


Lung cancer is one of the most incident neoplasms in the world, representing the main cause of mortality for cancer. Many epidemiologic studies have suggested that physical activity may reduce the risk of lung cancer, other works evaluate the effectiveness of the use of the physical activity in the suppression, remission and reduction of the recurrence of tumors. The aim of this study was to evaluate the effects of aerobic and anaerobic physical activity in the development and the progression of lung cancer. Lung tumors were induced with a dose of 3mg of urethane/kg, in 67 male Balb – C type mice, divided in three groups: group 1_24 mice treated with urethane and without physical activity; group 2_25 mice with urethane and subjected to aerobic swimming free exercise; group 3_18 mice with urethane, subjected to anaerobic swimming exercise with gradual loading 5-20% of body weight. All the animals were sacrificed after 20 weeks, and lung lesions were analyzed. The median number of lesions (nodules and hyperplasia) was 3.0 for group 1, 2.0 for group 2 and 1.5-3 (p=0.052). When comparing only the presence or absence of lesion, there was a decrease in the number of lesions in group 3 as compared with group 1 (p=0.03) but not in relation to group 2. There were no metastases or other changes in other organs. The anaerobic physical activity, but not aerobic, diminishes the incidence of experimental lung tumors.


US National Library of MedicineNational Institutes of HealthSearch databasePMCPubMedAll DatabasesAssemblyBiocollectionsBioProjectBioSampleBioSystemsBooksClinVarConserved DomainsdbGaPdbVarGeneGenomeGEO DataSetsGEO ProfilesGTRHomoloGeneIdentical Protein GroupsMedGenMeSHNCBI Web SiteNLM CatalogNucleotideOMIMPMCPopSetProbeProteinProtein ClustersPubChem BioAssayPubChem CompoundPubChem SubstancePubMedSNPSparcleSRAStructureTaxonomyToolKitToolKitAllToolKitBookghSearch term

Clear input


Try the new PubMed!

Result Filters

Send to

Science. 2003 Nov 14;302(5648):1172-5.

Human population: the next half century.

Cohen JE1.

Author information

1Rockefeller University and Columbia University, 1230 New York Avenue, Box 20, New York, NY 10021, USA.


By 2050, the human population will probably be larger by 2 to 4 billion people, more slowly growing (declining in the more developed regions), more urban, especially in less developed regions, and older than in the 20th century. Two major demographic uncertainties in the next 50 years concern international migration and the structure of families. Economies, nonhuman environments, and cultures (including values, religions, and politics) strongly influence demographic changes. Hence, human choices, individual and collective, will have demographic effects, intentional or otherwise.PMID: 14615528 DOI: 10.1126/science.1088665[Indexed for MEDLINE]

  • Share on Facebook
  • Share on Twitter
  • Share on Google+

Publication type, MeSH terms

LinkOut – more resources

Supplemental Content

Full text links

Save items

Add to FavoritesView more options

Similar articles

See reviews…See all…

Cited by 86 PubMed Central articles

See all…

Related information

Recent Activity

ClearTurn Off

See more…You are here: NCBI > Literature > PubMedSupport Center

Simple NCBI Directory

National Center for Biotechnology InformationU.S. National Library of Medicine8600 Rockville Pike, Bethesda MD, 20894 USAPolicies and Guidelines | Contact

Skip to main contentBecome a MemberLog InScienceMag.orgSearch




Human Population: The Next Half Century

  1. Joel E. Cohen

 See all authors and affiliationsScience  14 Nov 2003:
Vol. 302, Issue 5648, pp. 1172-1175
DOI: 10.1126/science.1088665

You are currently viewing the abstract.View Full Text

Log in to view the full text

via AAAS login

AAAS login provides access to Science for AAAS members, and access to other journals in the Science family to users who have purchased individual subscriptions.

Log in via OpenAthens.Log in with your institution via Shibboleth.

More options

Download and print this article for your personal scholarly, research, and educational use.

Buy a single issue of Science for just $15 USD.


By 2050, the human population will probably be larger by 2 to 4 billion people, more slowly growing (declining in the more developed regions), more urban, especially in less developed regions, and older than in the 20th century. Two major demographic uncertainties in the next 50 years concern international migration and the structure of families. Economies, nonhuman environments, and cultures (including values, religions, and politics) strongly influence demographic changes. Hence, human choices, individual and collective, will have demographic effects, intentional or otherwise.View Full Text

Science: 302 (5648)


Vol 302, Issue 5648
14 November 2003









Read the Latest Issue of Science

7 February 2020

Vol 367, Issue 6478

Table of Contents

Get Our E-Alerts

Receive emails from Science. See full listScience Table of ContentsScience Daily NewsWeekly News RoundupScience Editor’s ChoiceFirst Release NotificationScience Careers Job SeekerCountryCountry*AfghanistanAland IslandsAlbaniaAlgeriaAndorraAngolaAnguillaAntarcticaAntigua and BarbudaArgentinaArmeniaArubaAustraliaAustriaAzerbaijanBahamasBahrainBangladeshBarbadosBelarusBelgiumBelizeBeninBermudaBhutanBolivia, Plurinational State ofBonaire, Sint Eustatius and SabaBosnia and HerzegovinaBotswanaBouvet IslandBrazilBritish Indian Ocean TerritoryBrunei DarussalamBulgariaBurkina FasoBurundiCambodiaCameroonCanadaCape VerdeCayman IslandsCentral African RepublicChadChileChinaChristmas IslandCocos (Keeling) IslandsColombiaComorosCongoCongo, The Democratic Republic of theCook IslandsCosta RicaCote D’IvoireCroatiaCubaCuraçaoCyprusCzech RepublicDenmarkDjiboutiDominicaDominican RepublicEcuadorEgyptEl SalvadorEquatorial GuineaEritreaEstoniaEthiopiaFalkland Islands (Malvinas)Faroe IslandsFijiFinlandFranceFrench GuianaFrench PolynesiaFrench Southern TerritoriesGabonGambiaGeorgiaGermanyGhanaGibraltarGreeceGreenlandGrenadaGuadeloupeGuatemalaGuernseyGuineaGuinea-BissauGuyanaHaitiHeard Island and Mcdonald IslandsHoly See (Vatican City State)HondurasHong KongHungaryIcelandIndiaIndonesiaIran, Islamic Republic ofIraqIrelandIsle of ManIsraelItalyJamaicaJapanJerseyJordanKazakhstanKenyaKiribatiKorea, Democratic People’s Republic ofKorea, Republic ofKuwaitKyrgyzstanLao People’s Democratic RepublicLatviaLebanonLesothoLiberiaLibyan Arab JamahiriyaLiechtensteinLithuaniaLuxembourgMacaoMacedonia, The Former Yugoslav Republic ofMadagascarMalawiMalaysiaMaldivesMaliMaltaMartiniqueMauritaniaMauritiusMayotteMexicoMoldova, Republic ofMonacoMongoliaMontenegroMontserratMoroccoMozambiqueMyanmarNamibiaNauruNepalNetherlandsNew CaledoniaNew ZealandNicaraguaNigerNigeriaNiueNorfolk IslandNorwayOmanPakistanPalestinianPanamaPapua New GuineaParaguayPeruPhilippinesPitcairnPolandPortugalQatarReunionRomaniaRussian FederationRWANDASaint Barthélemy Saint Helena, Ascension and Tristan da CunhaSaint Kitts and NevisSaint LuciaSaint Martin (French part)Saint Pierre and MiquelonSaint Vincent and the GrenadinesSamoaSan MarinoSao Tome and PrincipeSaudi ArabiaSenegalSerbiaSeychellesSierra LeoneSingaporeSint Maarten (Dutch part)SlovakiaSloveniaSolomon IslandsSomaliaSouth AfricaSouth Georgia and the South Sandwich IslandsSouth SudanSpainSri LankaSudanSurinameSvalbard and Jan MayenSwazilandSwedenSwitzerlandSyrian Arab RepublicTaiwanTajikistanTanzania, United Republic ofThailandTimor-LesteTogoTokelauTongaTrinidad and TobagoTunisiaTurkeyTurkmenistanTurks and Caicos IslandsTuvaluUgandaUkraineUnited Arab EmiratesUnited KingdomUnited StatesUruguayUzbekistanVanuatuVenezuela, Bolivarian Republic ofVietnamVirgin Islands, BritishWallis and FutunaWestern SaharaYemenZambiaZimbabwe

Email I agree to receive emails from AAAS/Science
and Science advertisers, including information on 
products, services, and special offers which may
include but are not limited to news, career
information, & upcoming events.Sign up today

Required fields are indicated by an asterisk (*)


© 2020 American Association for the Advancement of Science. All rights reserved. AAAS is a partner of HINARIAGORAOARECHORUSCLOCKSSCrossRef and COUNTER.
Science ISSN 1095-9203.

This website uses cookies to ensure you get the best experience on our website. Learn moreGot it!


Development >> Mobile Apps

Android Tutorial for Beginners . Make App That Sells

Learn to create your own Android apps that you can publish .

Ratings 4.21 / 5.00


The Android operating system is changing our lives in so many ways and also enabled enterprises to develop into big names in the IT business. It has the biggest database of users around the world and the numbers are only increasing. With the boom of mobile devices, the android app market has grown majorly, with the addition of new and innovative apps regularly.

Learn everything you need to know to get started building Android apps with the Android Studio IDE. You will learn to set up your Android SDK and begin developing by incorporating UI, buttons, intents etc .This course is designed around the basics and once you complete the course, you will easily be able to create a brilliant Android app. The curriculum includes Installation, Activities, Layouts, List Views, SQLite and Services Multimedia .

What You Will Learn!

  • Create visually appealing app
  • Know how to select the layout for your apps
  • Become conversant with the Android platform

Who Should Attend!

  • Android enthusiasts
  • Students
  • Beginners to Android development



  • Android Development





Shop Related Products

Android Application Development All-in-One For Dummies, 2nd Edition$27.85$39.99 (17)

Head First Android Development: A Brain-Friendly Guide$36.99$69.99 (24)Ads by Amazon

Related Courses

Unreal Engine 4: Come creare un app android per architettura

Unreal Engine 4: Come creare un app android per ar…

Machine Learning for Android Developer using Tensorflow lite

Machine Learning for Android Developer using Tenso…

Practical Deep Learning: Geolocalizzazione indoor (Italiano)

Practical Deep Learning: Geolocalizzazione indoor…

Test-Driven Android

Test-Driven Android

Learn Android App continuous integration using CircleCI

Learn Android App continuous integration using Cir…

Popular Categories
University Courses

© 2020 Share Tweet Pin Email Share Share

This is a featured article. Click here for more information.
Page semi-protected
Listen to this article


From Wikipedia, the free encyclopediaJump to navigationJump to searchFor a non-technical introduction to the topic, see Introduction to genetics. For other uses, see DNA (disambiguation).The structure of the DNA double helix. The atoms in the structure are colour-coded by element and the detailed structures of two base pairs are shown in the bottom right.The structure of part of a DNA double helix

Deoxyribonucleic acid (/diːˈɒksɪˌraɪboʊnjuːˌkliːɪk, -ˌkleɪ-/ (listen);[1] DNA) is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. DNA and ribonucleic acid (RNA) are nucleic acids; alongside proteinslipids and complex carbohydrates (polysaccharides), nucleic acids are one of the four major types of macromolecules that are essential for all known forms of life.

The two DNA strands are also known as polynucleotides as they are composed of simpler monomeric units called nucleotides.[2][3] Each nucleotide is composed of one of four nitrogen-containing nucleobases (cytosine [C], guanine [G], adenine [A] or thymine [T]), a sugar called deoxyribose, and a phosphate group. The nucleotides are joined to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone. The nitrogenous bases of the two separate polynucleotide strands are bound together, according to base pairing rules (A with T and C with G), with hydrogen bonds to make double-stranded DNA. The complementary nitrogenous bases are divided into two groups, pyrimidines and purines. In DNA, the pyrimidines are thymine and cytosine; the purines are adenine and guanine.

Both strands of double-stranded DNA store the same biological information. This information is replicated as and when the two strands separate. A large part of DNA (more than 98% for humans) is non-coding, meaning that these sections do not serve as patterns for protein sequences. The two strands of DNA run in opposite directions to each other and are thus antiparallel. Attached to each sugar is one of four types of nucleobases (informally, bases). It is the sequence of these four nucleobases along the backbone that encodes genetic information. RNA strands are created using DNA strands as a template in a process called transcription, where DNA bases are exchanged for their corresponding bases except in the case of thymine (T), which RNA substitutes for uracil (U).[4] Under the genetic code, these RNA strands specify the sequence of amino acids within proteins in a process called translation.

Within eukaryotic cells, DNA is organized into long structures called chromosomes. Before typical cell division, these chromosomes are duplicated in the process of DNA replication, providing a complete set of chromosomes for each daughter cell. Eukaryotic organisms (animalsplantsfungi and protists) store most of their DNA inside the cell nucleus as nuclear DNA, and some in the mitochondria as mitochondrial DNA or in chloroplasts as chloroplast DNA.[5] In contrast, prokaryotes (bacteria and archaea) store their DNA only in the cytoplasm, in circular chromosomes. Within eukaryotic chromosomes, chromatin proteins, such as histones, compact and organize DNA. These compacting structures guide the interactions between DNA and other proteins, helping control which parts of the DNA are transcribed.

DNA was first isolated by Friedrich Miescher in 1869. Its molecular structure was first identified by Francis Crick and James Watson at the Cavendish Laboratory within the University of Cambridge in 1953, whose model-building efforts were guided by X-ray diffraction data acquired by Raymond Gosling, who was a post-graduate student of Rosalind Franklin at King’s College London. DNA is used by researchers as a molecular tool to explore physical laws and theories, such as the ergodic theorem and the theory of elasticity. The unique material properties of DNA have made it an attractive molecule for material scientists and engineers interested in micro- and nano-fabrication. Among notable advances in this field are DNA origami and DNA-based hybrid materials.[6]



Chemical structure of DNA; hydrogen bonds shown as dotted lines

DNA is a long polymer made from repeating units called nucleotides, each of which is usually symbolized by a single letter: either A, T, C, or G.[7][8] The structure of DNA is dynamic along its length, being capable of coiling into tight loops and other shapes.[9] In all species it is composed of two helical chains, bound to each other by hydrogen bonds. Both chains are coiled around the same axis, and have the same pitch of 34 angstroms (Å) (3.4 nanometres). The pair of chains has a radius of 10 angstroms (1.0 nanometre).[10] According to another study, when measured in a different solution, the DNA chain measured 22 to 26 angstroms wide (2.2 to 2.6 nanometres), and one nucleotide unit measured 3.3 Å (0.33 nm) long.[11] Although each individual nucleotide is very small, a DNA polymer can be very large and contain hundreds of millions, such as in chromosome 1. Chromosome 1 is the largest human chromosome with approximately 220 million base pairs, and would be 85 mm long if straightened.[12]

DNA does not usually exist as a single strand, but instead as a pair of strands that are held tightly together.[10][13] These two long strands coil around each other, in the shape of a double helix. The nucleotide contains both a segment of the backbone of the molecule (which holds the chain together) and a nucleobase (which interacts with the other DNA strand in the helix). A nucleobase linked to a sugar is called a nucleoside, and a base linked to a sugar and to one or more phosphate groups is called a nucleotide. A biopolymer comprising multiple linked nucleotides (as in DNA) is called a polynucleotide.[14]

The backbone of the DNA strand is made from alternating phosphate and sugar groups.[15] The sugar in DNA is 2-deoxyribose, which is a pentose (five-carbon) sugar. The sugars are joined together by phosphate groups that form phosphodiester bonds between the third and fifth carbon atoms of adjacent sugar rings. These are known as the 3′-end (three prime end), and 5′-end (five prime end) carbons, the prime symbol being used to distinguish these carbon atoms from those of the base to which the deoxyribose forms a glycosidic bond. Therefore, any DNA strand normally has one end at which there is a phosphate group attached to the 5′ carbon of a ribose (the 5′ phosphoryl) and another end at which there is a free hydroxyl group attached to the 3′ carbon of a ribose (the 3′ hydroxyl). The orientation of the 3′ and 5′ carbons along the sugar-phosphate backbone confers directionality (sometimes called polarity) to each DNA strand. In a nucleic acid double helix, the direction of the nucleotides in one strand is opposite to their direction in the other strand: the strands are antiparallel. The asymmetric ends of DNA strands are said to have a directionality of five prime end (5′ ), and three prime end (3′), with the 5′ end having a terminal phosphate group and the 3′ end a terminal hydroxyl group. One major difference between DNA and RNA is the sugar, with the 2-deoxyribose in DNA being replaced by the alternative pentose sugar ribose in RNA.[13]A section of DNA. The bases lie horizontally between the two spiraling strands[16] (animated version).

The DNA double helix is stabilized primarily by two forces: hydrogen bonds between nucleotides and base-stacking interactions among aromatic nucleobases.[17] The four bases found in DNA are adenine (A), cytosine (C), guanine (G) and thymine (T). These four bases are attached to the sugar-phosphate to form the complete nucleotide, as shown for adenosine monophosphate. Adenine pairs with thymine and guanine pairs with cytosine, forming A-T and G-C base pairs.[18][19]

Nucleobase classification

The nucleobases are classified into two types: the purines, A and G, which are fused five- and six-membered heterocyclic compounds, and the pyrimidines, the six-membered rings C and T.[13] A fifth pyrimidine nucleobase, uracil (U), usually takes the place of thymine in RNA and differs from thymine by lacking a methyl group on its ring. In addition to RNA and DNA, many artificial nucleic acid analogues have been created to study the properties of nucleic acids, or for use in biotechnology.[20]

Non-canonical bases

Modified bases occur in DNA. The first of these recognised was 5-methylcytosine, which was found in the genome of Mycobacterium tuberculosis in 1925.[21] The reason for the presence of these noncanonical bases in bacterial viruses (bacteriophages) is to avoid the restriction enzymes present in bacteria. This enzyme system acts at least in part as a molecular immune system protecting bacteria from infection by viruses.[22] Modifications of the bases cytosine and adenine the more common and modified DNA bases plays vital roles in the epigenetic control of gene expression in plants and animals.[23]

Listing of non-canonical bases found in DNA

A number of non canonical bases are known to occur in DNA.[24] Most of these are modifications of the canonical bases plus uracil.

  • Modified Adenosine
    • N6-carbamoyl-methyladenine
    • N6-methyadenine
  • Modified Guanine
    • 7-Deazaguanine
    • 7-Methylguanine
  • Modified Cytosine
    • N4-Methylcytosine
    • 5-Carboxylcytosine
    • 5-Formylcytosine
    • 5-Glycosylhydroxymethylcytosine
    • 5-Hydroxycytosine
    • 5-Methylcytosine
  • Modified Thymidine
    • α-Glutamythymidine
    • α-Putrescinylthymine
  • Uracil and modifications
    • Base J
    • Uracil
    • 5-Dihydroxypentauracil
    • 5-Hydroxymethyldeoxyuracil
  • Others
    • Deoxyarchaeosine
    • 2,6-Diaminopurine

DNA major and minor grooves. The latter is a binding site for the Hoechst stain dye 33258.


Twin helical strands form the DNA backbone. Another double helix may be found tracing the spaces, or grooves, between the strands. These voids are adjacent to the base pairs and may provide a binding site. As the strands are not symmetrically located with respect to each other, the grooves are unequally sized. One groove, the major groove, is 22 angstroms (Å) wide and the other, the minor groove, is 12 Å wide.[25] The width of the major groove means that the edges of the bases are more accessible in the major groove than in the minor groove. As a result, proteins such as transcription factors that can bind to specific sequences in double-stranded DNA usually make contact with the sides of the bases exposed in the major groove.[26] This situation varies in unusual conformations of DNA within the cell (see below), but the major and minor grooves are always named to reflect the differences in size that would be seen if the DNA is twisted back into the ordinary B form.

Base pairing

Further information: Base pair

In a DNA double helix, each type of nucleobase on one strand bonds with just one type of nucleobase on the other strand. This is called complementary base pairing. Purines form hydrogen bonds to pyrimidines, with adenine bonding only to thymine in two hydrogen bonds, and cytosine bonding only to guanine in three hydrogen bonds. This arrangement of two nucleotides binding together across the double helix is called a Watson-Crick base pair. DNA with high GC-content is more stable than DNA with low GC-content. A Hoogsteen base pair is a rare variation of base-pairing.[27] As hydrogen bonds are not covalent, they can be broken and rejoined relatively easily. The two strands of DNA in a double helix can thus be pulled apart like a zipper, either by a mechanical force or high temperature.[28] As a result of this base pair complementarity, all the information in the double-stranded sequence of a DNA helix is duplicated on each strand, which is vital in DNA replication. This reversible and specific interaction between complementary base pairs is critical for all the functions of DNA in organisms.[8]

Top, a GC base pair with three hydrogen bonds. Bottom, an AT base pair with two hydrogen bonds. Non-covalent hydrogen bonds between the pairs are shown as dashed lines.

As noted above, most DNA molecules are actually two polymer strands, bound together in a helical fashion by noncovalent bonds; this double-stranded (dsDNA) structure is maintained largely by the intrastrand base stacking interactions, which are strongest for G,C stacks. The two strands can come apart—a process known as melting—to form two single-stranded DNA (ssDNA) molecules. Melting occurs at high temperature, low salt and high pH (low pH also melts DNA, but since DNA is unstable due to acid depurination, low pH is rarely used).

The stability of the dsDNA form depends not only on the GC-content (% G,C basepairs) but also on sequence (since stacking is sequence specific) and also length (longer molecules are more stable). The stability can be measured in various ways; a common way is the “melting temperature”, which is the temperature at which 50% of the ds molecules are converted to ss molecules; melting temperature is dependent on ionic strength and the concentration of DNA. As a result, it is both the percentage of GC base pairs and the overall length of a DNA double helix that determines the strength of the association between the two strands of DNA. Long DNA helices with a high GC-content have stronger-interacting strands, while short helices with high AT content have weaker-interacting strands.[29] In biology, parts of the DNA double helix that need to separate easily, such as the TATAAT Pribnow box in some promoters, tend to have a high AT content, making the strands easier to pull apart.[30]

In the laboratory, the strength of this interaction can be measured by finding the temperature necessary to break half of the hydrogen bonds, their melting temperature (also called Tm value). When all the base pairs in a DNA double helix melt, the strands separate and exist in solution as two entirely independent molecules. These single-stranded DNA molecules have no single common shape, but some conformations are more stable than others.[31]

Sense and antisense

Further information: Sense (molecular biology)

DNA sequence is called a “sense” sequence if it is the same as that of a messenger RNA copy that is translated into protein.[32] The sequence on the opposite strand is called the “antisense” sequence. Both sense and antisense sequences can exist on different parts of the same strand of DNA (i.e. both strands can contain both sense and antisense sequences). In both prokaryotes and eukaryotes, antisense RNA sequences are produced, but the functions of these RNAs are not entirely clear.[33] One proposal is that antisense RNAs are involved in regulating gene expression through RNA-RNA base pairing.[34]

A few DNA sequences in prokaryotes and eukaryotes, and more in plasmids and viruses, blur the distinction between sense and antisense strands by having overlapping genes.[35] In these cases, some DNA sequences do double duty, encoding one protein when read along one strand, and a second protein when read in the opposite direction along the other strand. In bacteria, this overlap may be involved in the regulation of gene transcription,[36] while in viruses, overlapping genes increase the amount of information that can be encoded within the small viral genome.[37]


Further information: DNA supercoil

DNA can be twisted like a rope in a process called DNA supercoiling. With DNA in its “relaxed” state, a strand usually circles the axis of the double helix once every 10.4 base pairs, but if the DNA is twisted the strands become more tightly or more loosely wound.[38] If the DNA is twisted in the direction of the helix, this is positive supercoiling, and the bases are held more tightly together. If they are twisted in the opposite direction, this is negative supercoiling, and the bases come apart more easily. In nature, most DNA has slight negative supercoiling that is introduced by enzymes called topoisomerases.[39] These enzymes are also needed to relieve the twisting stresses introduced into DNA strands during processes such as transcription and DNA replication.[40]From left to right, the structures of A, B and Z DNA

Alternative DNA structures

Further information: Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic AcidMolecular models of DNA, and DNA structure

DNA exists in many possible conformations that include A-DNA, B-DNA, and Z-DNA forms, although, only B-DNA and Z-DNA have been directly observed in functional organisms.[15] The conformation that DNA adopts depends on the hydration level, DNA sequence, the amount and direction of supercoiling, chemical modifications of the bases, the type and concentration of metal ions, and the presence of polyamines in solution.[41]

The first published reports of A-DNA X-ray diffraction patterns—and also B-DNA—used analyses based on Patterson transforms that provided only a limited amount of structural information for oriented fibers of DNA.[42][43] An alternative analysis was then proposed by Wilkins et al., in 1953, for the in vivo B-DNA X-ray diffraction-scattering patterns of highly hydrated DNA fibers in terms of squares of Bessel functions.[44] In the same journal, James Watson and Francis Crick presented their molecular modeling analysis of the DNA X-ray diffraction patterns to suggest that the structure was a double-helix.[10]

Although the B-DNA form is most common under the conditions found in cells,[45] it is not a well-defined conformation but a family of related DNA conformations[46] that occur at the high hydration levels present in cells. Their corresponding X-ray diffraction and scattering patterns are characteristic of molecular paracrystals with a significant degree of disorder.[47][48]

Compared to B-DNA, the A-DNA form is a wider right-handed spiral, with a shallow, wide minor groove and a narrower, deeper major groove. The A form occurs under non-physiological conditions in partly dehydrated samples of DNA, while in the cell it may be produced in hybrid pairings of DNA and RNA strands, and in enzyme-DNA complexes.[49][50] Segments of DNA where the bases have been chemically modified by methylation may undergo a larger change in conformation and adopt the Z form. Here, the strands turn about the helical axis in a left-handed spiral, the opposite of the more common B form.[51] These unusual structures can be recognized by specific Z-DNA binding proteins and may be involved in the regulation of transcription.[52]

Alternative DNA chemistry

For many years, exobiologists have proposed the existence of a shadow biosphere, a postulated microbial biosphere of Earth that uses radically different biochemical and molecular processes than currently known life. One of the proposals was the existence of lifeforms that use arsenic instead of phosphorus in DNA. A report in 2010 of the possibility in the bacterium GFAJ-1, was announced,[53][53][54] though the research was disputed,[54][55] and evidence suggests the bacterium actively prevents the incorporation of arsenic into the DNA backbone and other biomolecules.[56]

Quadruplex structures

Further information: G-quadruplex

At the ends of the linear chromosomes are specialized regions of DNA called telomeres. The main function of these regions is to allow the cell to replicate chromosome ends using the enzyme telomerase, as the enzymes that normally replicate DNA cannot copy the extreme 3′ ends of chromosomes.[57] These specialized chromosome caps also help protect the DNA ends, and stop the DNA repair systems in the cell from treating them as damage to be corrected.[58] In human cells, telomeres are usually lengths of single-stranded DNA containing several thousand repeats of a simple TTAGGG sequence.[59]DNA quadruplex formed by telomere repeats. The looped conformation of the DNA backbone is very different from the typical DNA helix. The green spheres in the center represent potassium ions.[60]

These guanine-rich sequences may stabilize chromosome ends by forming structures of stacked sets of four-base units, rather than the usual base pairs found in other DNA molecules. Here, four guanine bases form a flat plate and these flat four-base units then stack on top of each other, to form a stable G-quadruplex structure.[61] These structures are stabilized by hydrogen bonding between the edges of the bases and chelation of a metal ion in the centre of each four-base unit.[62] Other structures can also be formed, with the central set of four bases coming from either a single strand folded around the bases, or several different parallel strands, each contributing one base to the central structure.

In addition to these stacked structures, telomeres also form large loop structures called telomere loops, or T-loops. Here, the single-stranded DNA curls around in a long circle stabilized by telomere-binding proteins.[63] At the very end of the T-loop, the single-stranded telomere DNA is held onto a region of double-stranded DNA by the telomere strand disrupting the double-helical DNA and base pairing to one of the two strands. This triple-stranded structure is called a displacement loop or D-loop.[61]

Single branchMultiple branches

Branched DNA can form networks containing multiple branches.

Branched DNA

Further information: Branched DNA and DNA nanotechnology

In DNA, fraying occurs when non-complementary regions exist at the end of an otherwise complementary double-strand of DNA. However, branched DNA can occur if a third strand of DNA is introduced and contains adjoining regions able to hybridize with the frayed regions of the pre-existing double-strand. Although the simplest example of branched DNA involves only three strands of DNA, complexes involving additional strands and multiple branches are also possible.[64] Branched DNA can be used in nanotechnology to construct geometric shapes, see the section on uses in technology below.

Artificial bases

Main article: Nucleic acid analogue

Several artificial nucleobases have been synthesized, and successfully incorporated in the eight-base DNA analogue named Hachimoji DNA. Dubbed S, B, P, and Z, these artificial bases are capable of bonding with each other in a predictable way (S–B and P–Z), maintain the double helix structure of DNA, and be transcribed to RNA. Their existence implies that there is nothing special about the four natural nucleobases that evolved on Earth.[65][66]

Chemical modifications and altered DNA packaging


Structure of cytosine with and without the 5-methyl group. Deamination converts 5-methylcytosine into thymine.

Base modifications and DNA packaging

Further information: DNA methylation and Chromatin remodeling

The expression of genes is influenced by how the DNA is packaged in chromosomes, in a structure called chromatin. Base modifications can be involved in packaging, with regions that have low or no gene expression usually containing high levels of methylation of cytosine bases. DNA packaging and its influence on gene expression can also occur by covalent modifications of the histone protein core around which DNA is wrapped in the chromatin structure or else by remodeling carried out by chromatin remodeling complexes (see Chromatin remodeling). There is, further, crosstalk between DNA methylation and histone modification, so they can coordinately affect chromatin and gene expression.[67]

For one example, cytosine methylation produces 5-methylcytosine, which is important for X-inactivation of chromosomes.[68] The average level of methylation varies between organisms—the worm Caenorhabditis elegans lacks cytosine methylation, while vertebrates have higher levels, with up to 1% of their DNA containing 5-methylcytosine.[69] Despite the importance of 5-methylcytosine, it can deaminate to leave a thymine base, so methylated cytosines are particularly prone to mutations.[70] Other base modifications include adenine methylation in bacteria, the presence of 5-hydroxymethylcytosine in the brain,[71] and the glycosylation of uracil to produce the “J-base” in kinetoplastids.[72][73]


Further information: DNA damage (naturally occurring)Mutation, and DNA damage theory of agingcovalentadduct between a metabolically activated form of benzo[a]pyrene, the major mutagen in tobacco smoke, and DNA[74]

DNA can be damaged by many sorts of mutagens, which change the DNA sequence. Mutagens include oxidizing agentsalkylating agents and also high-energy electromagnetic radiation such as ultraviolet light and X-rays. The type of DNA damage produced depends on the type of mutagen. For example, UV light can damage DNA by producing thymine dimers, which are cross-links between pyrimidine bases.[75] On the other hand, oxidants such as free radicals or hydrogen peroxide produce multiple forms of damage, including base modifications, particularly of guanosine, and double-strand breaks.[76] A typical human cell contains about 150,000 bases that have suffered oxidative damage.[77] Of these oxidative lesions, the most dangerous are double-strand breaks, as these are difficult to repair and can produce point mutationsinsertionsdeletions from the DNA sequence, and chromosomal translocations.[78] These mutations can cause cancer. Because of inherent limits in the DNA repair mechanisms, if humans lived long enough, they would all eventually develop cancer.[79][80] DNA damages that are naturally occurring, due to normal cellular processes that produce reactive oxygen species, the hydrolytic activities of cellular water, etc., also occur frequently. Although most of these damages are repaired, in any cell some DNA damage may remain despite the action of repair processes. These remaining DNA damages accumulate with age in mammalian postmitotic tissues. This accumulation appears to be an important underlying cause of aging.[81][82][83]

Many mutagens fit into the space between two adjacent base pairs, this is called intercalation. Most intercalators are aromatic and planar molecules; examples include ethidium bromideacridinesdaunomycin, and doxorubicin. For an intercalator to fit between base pairs, the bases must separate, distorting the DNA strands by unwinding of the double helix. This inhibits both transcription and DNA replication, causing toxicity and mutations.[84] As a result, DNA intercalators may be carcinogens, and in the case of thalidomide, a teratogen.[85] Others such as benzo[a]pyrene diol epoxide and aflatoxin form DNA adducts that induce errors in replication.[86] Nevertheless, due to their ability to inhibit DNA transcription and replication, other similar toxins are also used in chemotherapy to inhibit rapidly growing cancer cells.[87]

Biological functions

Location of eukaryote nuclear DNA within the chromosomes

DNA usually occurs as linear chromosomes in eukaryotes, and circular chromosomes in prokaryotes. The set of chromosomes in a cell makes up its genome; the human genome has approximately 3 billion base pairs of DNA arranged into 46 chromosomes.[88] The information carried by DNA is held in the sequence of pieces of DNA called genesTransmission of genetic information in genes is achieved via complementary base pairing. For example, in transcription, when a cell uses the information in a gene, the DNA sequence is copied into a complementary RNA sequence through the attraction between the DNA and the correct RNA nucleotides. Usually, this RNA copy is then used to make a matching protein sequence in a process called translation, which depends on the same interaction between RNA nucleotides. In alternative fashion, a cell may simply copy its genetic information in a process called DNA replication. The details of these functions are covered in other articles; here the focus is on the interactions between DNA and other molecules that mediate the function of the genome.

Genes and genomes

Further information: Cell nucleusChromatinChromosomeGene, and Noncoding DNA

Genomic DNA is tightly and orderly packed in the process called DNA condensation, to fit the small available volumes of the cell. In eukaryotes, DNA is located in the cell nucleus, with small amounts in mitochondria and chloroplasts. In prokaryotes, the DNA is held within an irregularly shaped body in the cytoplasm called the nucleoid.[89] The genetic information in a genome is held within genes, and the complete set of this information in an organism is called its genotype. A gene is a unit of heredity and is a region of DNA that influences a particular characteristic in an organism. Genes contain an open reading frame that can be transcribed, and regulatory sequences such as promoters and enhancers, which control transcription of the open reading frame.

In many species, only a small fraction of the total sequence of the genome encodes protein. For example, only about 1.5% of the human genome consists of protein-coding exons, with over 50% of human DNA consisting of non-coding repetitive sequences.[90] The reasons for the presence of so much noncoding DNA in eukaryotic genomes and the extraordinary differences in genome size, or C-value, among species, represent a long-standing puzzle known as the “C-value enigma“.[91] However, some DNA sequences that do not code protein may still encode functional non-coding RNA molecules, which are involved in the regulation of gene expression.[92]T7 RNA polymerase (blue) producing an mRNA (green) from a DNA template (orange)[93]

Some noncoding DNA sequences play structural roles in chromosomes. Telomeres and centromeres typically contain few genes but are important for the function and stability of chromosomes.[58][94] An abundant form of noncoding DNA in humans are pseudogenes, which are copies of genes that have been disabled by mutation.[95] These sequences are usually just molecular fossils, although they can occasionally serve as raw genetic material for the creation of new genes through the process of gene duplication and divergence.[96]

Transcription and translation

Further information: Genetic codeTranscription (genetics), and Protein biosynthesis

A gene is a sequence of DNA that contains genetic information and can influence the phenotype of an organism. Within a gene, the sequence of bases along a DNA strand defines a messenger RNA sequence, which then defines one or more protein sequences. The relationship between the nucleotide sequences of genes and the amino-acid sequences of proteins is determined by the rules of translation, known collectively as the genetic code. The genetic code consists of three-letter ‘words’ called codons formed from a sequence of three nucleotides (e.g. ACT, CAG, TTT).

In transcription, the codons of a gene are copied into messenger RNA by RNA polymerase. This RNA copy is then decoded by a ribosome that reads the RNA sequence by base-pairing the messenger RNA to transfer RNA, which carries amino acids. Since there are 4 bases in 3-letter combinations, there are 64 possible codons (43 combinations). These encode the twenty standard amino acids, giving most amino acids more than one possible codon. There are also three ‘stop’ or ‘nonsense’ codons signifying the end of the coding region; these are the TAA, TGA, and TAG codons.DNA replication: The double helix is unwound by a helicase and topo­iso­merase. Next, one DNA polymerase produces the leading strand copy. Another DNA polymerase binds to the lagging strand. This enzyme makes discontinuous segments (called Okazaki fragments) before DNA ligase joins them together.


Further information: DNA replication

Cell division is essential for an organism to grow, but, when a cell divides, it must replicate the DNA in its genome so that the two daughter cells have the same genetic information as their parent. The double-stranded structure of DNA provides a simple mechanism for DNA replication. Here, the two strands are separated and then each strand’s complementary DNA sequence is recreated by an enzyme called DNA polymerase. This enzyme makes the complementary strand by finding the correct base through complementary base pairing and bonding it onto the original strand. As DNA polymerases can only extend a DNA strand in a 5′ to 3′ direction, different mechanisms are used to copy the antiparallel strands of the double helix.[97] In this way, the base on the old strand dictates which base appears on the new strand, and the cell ends up with a perfect copy of its DNA.

Extracellular nucleic acids

Naked extracellular DNA (eDNA), most of it released by cell death, is nearly ubiquitous in the environment. Its concentration in soil may be as high as 2 μg/L, and its concentration in natural aquatic environments may be as high at 88 μg/L.[98] Various possible functions have been proposed for eDNA: it may be involved in horizontal gene transfer;[99] it may provide nutrients;[100] and it may act as a buffer to recruit or titrate ions or antibiotics.[101] Extracellular DNA acts as a functional extracellular matrix component in the biofilms of several bacterial species. It may act as a recognition factor to regulate the attachment and dispersal of specific cell types in the biofilm;[102] it may contribute to biofilm formation;[103] and it may contribute to the biofilm’s physical strength and resistance to biological stress.[104]

Cell-free fetal DNA is found in the blood of the mother, and can be sequenced to determine a great deal of information about the developing fetus.[105]

Interactions with proteins

All the functions of DNA depend on interactions with proteins. These protein interactions can be non-specific, or the protein can bind specifically to a single DNA sequence. Enzymes can also bind to DNA and of these, the polymerases that copy the DNA base sequence in transcription and DNA replication are particularly important.

DNA-binding proteins

Further information: DNA-binding proteinInteraction of DNA (in orange) with histones (in blue). These proteins’ basic amino acids bind to the acidic phosphate groups on DNA.

Structural proteins that bind DNA are well-understood examples of non-specific DNA-protein interactions. Within chromosomes, DNA is held in complexes with structural proteins. These proteins organize the DNA into a compact structure called chromatin. In eukaryotes, this structure involves DNA binding to a complex of small basic proteins called histones, while in prokaryotes multiple types of proteins are involved.[106][107] The histones form a disk-shaped complex called a nucleosome, which contains two complete turns of double-stranded DNA wrapped around its surface. These non-specific interactions are formed through basic residues in the histones, making ionic bonds to the acidic sugar-phosphate backbone of the DNA, and are thus largely independent of the base sequence.[108] Chemical modifications of these basic amino acid residues include methylationphosphorylation, and acetylation.[109] These chemical changes alter the strength of the interaction between the DNA and the histones, making the DNA more or less accessible to transcription factors and changing the rate of transcription.[110] Other non-specific DNA-binding proteins in chromatin include the high-mobility group proteins, which bind to bent or distorted DNA.[111] These proteins are important in bending arrays of nucleosomes and arranging them into the larger structures that make up chromosomes.[112]

A distinct group of DNA-binding proteins is the DNA-binding proteins that specifically bind single-stranded DNA. In humans, replication protein A is the best-understood member of this family and is used in processes where the double helix is separated, including DNA replication, recombination, and DNA repair.[113] These binding proteins seem to stabilize single-stranded DNA and protect it from forming stem-loops or being degraded by nucleases.The lambda repressor helix-turn-helix transcription factor bound to its DNA target[114]

In contrast, other proteins have evolved to bind to particular DNA sequences. The most intensively studied of these are the various transcription factors, which are proteins that regulate transcription. Each transcription factor binds to one particular set of DNA sequences and activates or inhibits the transcription of genes that have these sequences close to their promoters. The transcription factors do this in two ways. Firstly, they can bind the RNA polymerase responsible for transcription, either directly or through other mediator proteins; this locates the polymerase at the promoter and allows it to begin transcription.[115] Alternatively, transcription factors can bind enzymes that modify the histones at the promoter. This changes the accessibility of the DNA template to the polymerase.[116]

As these DNA targets can occur throughout an organism’s genome, changes in the activity of one type of transcription factor can affect thousands of genes.[117] Consequently, these proteins are often the targets of the signal transduction processes that control responses to environmental changes or cellular differentiation and development. The specificity of these transcription factors’ interactions with DNA come from the proteins making multiple contacts to the edges of the DNA bases, allowing them to “read” the DNA sequence. Most of these base-interactions are made in the major groove, where the bases are most accessible.[26]The restriction enzymeEcoRV (green) in a complex with its substrate DNA[118]

DNA-modifying enzymes

Nucleases and ligases

Nucleases are enzymes that cut DNA strands by catalyzing the hydrolysis of the phosphodiester bonds. Nucleases that hydrolyse nucleotides from the ends of DNA strands are called exonucleases, while endonucleases cut within strands. The most frequently used nucleases in molecular biology are the restriction endonucleases, which cut DNA at specific sequences. For instance, the EcoRV enzyme shown to the left recognizes the 6-base sequence 5′-GATATC-3′ and makes a cut at the horizontal line. In nature, these enzymes protect bacteria against phage infection by digesting the phage DNA when it enters the bacterial cell, acting as part of the restriction modification system.[119] In technology, these sequence-specific nucleases are used in molecular cloning and DNA fingerprinting.

Enzymes called DNA ligases can rejoin cut or broken DNA strands.[120] Ligases are particularly important in lagging strand DNA replication, as they join together the short segments of DNA produced at the replication fork into a complete copy of the DNA template. They are also used in DNA repair and genetic recombination.[120]

Topoisomerases and helicases

Topoisomerases are enzymes with both nuclease and ligase activity. These proteins change the amount of supercoiling in DNA. Some of these enzymes work by cutting the DNA helix and allowing one section to rotate, thereby reducing its level of supercoiling; the enzyme then seals the DNA break.[39] Other types of these enzymes are capable of cutting one DNA helix and then passing a second strand of DNA through this break, before rejoining the helix.[121] Topoisomerases are required for many processes involving DNA, such as DNA replication and transcription.[40]

Helicases are proteins that are a type of molecular motor. They use the chemical energy in nucleoside triphosphates, predominantly adenosine triphosphate (ATP), to break hydrogen bonds between bases and unwind the DNA double helix into single strands.[122] These enzymes are essential for most processes where enzymes need to access the DNA bases.


Polymerases are enzymes that synthesize polynucleotide chains from nucleoside triphosphates. The sequence of their products is created based on existing polynucleotide chains—which are called templates. These enzymes function by repeatedly adding a nucleotide to the 3′ hydroxyl group at the end of the growing polynucleotide chain. As a consequence, all polymerases work in a 5′ to 3′ direction.[123] In the active site of these enzymes, the incoming nucleoside triphosphate base-pairs to the template: this allows polymerases to accurately synthesize the complementary strand of their template. Polymerases are classified according to the type of template that they use.

In DNA replication, DNA-dependent DNA polymerases make copies of DNA polynucleotide chains. To preserve biological information, it is essential that the sequence of bases in each copy are precisely complementary to the sequence of bases in the template strand. Many DNA polymerases have a proofreading activity. Here, the polymerase recognizes the occasional mistakes in the synthesis reaction by the lack of base pairing between the mismatched nucleotides. If a mismatch is detected, a 3′ to 5′ exonuclease activity is activated and the incorrect base removed.[124] In most organisms, DNA polymerases function in a large complex called the replisome that contains multiple accessory subunits, such as the DNA clamp or helicases.[125]

RNA-dependent DNA polymerases are a specialized class of polymerases that copy the sequence of an RNA strand into DNA. They include reverse transcriptase, which is a viral enzyme involved in the infection of cells by retroviruses, and telomerase, which is required for the replication of telomeres.[57][126] For example, HIV reverse transcriptase is an enzyme for AIDS virus replication.[126] Telomerase is an unusual polymerase because it contains its own RNA template as part of its structure. It synthesizes telomeres at the ends of chromosomes. Telomeres prevent fusion of the ends of neighboring chromosomes and protect chromosome ends from damage.[58]

Transcription is carried out by a DNA-dependent RNA polymerase that copies the sequence of a DNA strand into RNA. To begin transcribing a gene, the RNA polymerase binds to a sequence of DNA called a promoter and separates the DNA strands. It then copies the gene sequence into a messenger RNA transcript until it reaches a region of DNA called the terminator, where it halts and detaches from the DNA. As with human DNA-dependent DNA polymerases, RNA polymerase II, the enzyme that transcribes most of the genes in the human genome, operates as part of a large protein complex with multiple regulatory and accessory subunits.[127]

Genetic recombination

Structure of the Holliday junction intermediate in genetic recombination. The four separate DNA strands are coloured red, blue, green and yellow.[128]Further information: Genetic recombinationRecombination involves the breaking and rejoining of two chromosomes (M and F) to produce two rearranged chromosomes (C1 and C2).

A DNA helix usually does not interact with other segments of DNA, and in human cells, the different chromosomes even occupy separate areas in the nucleus called “chromosome territories“.[129] This physical separation of different chromosomes is important for the ability of DNA to function as a stable repository for information, as one of the few times chromosomes interact is in chromosomal crossover which occurs during sexual reproduction, when genetic recombination occurs. Chromosomal crossover is when two DNA helices break, swap a section and then rejoin.

Recombination allows chromosomes to exchange genetic information and produces new combinations of genes, which increases the efficiency of natural selection and can be important in the rapid evolution of new proteins.[130] Genetic recombination can also be involved in DNA repair, particularly in the cell’s response to double-strand breaks.[131]

The most common form of chromosomal crossover is homologous recombination, where the two chromosomes involved share very similar sequences. Non-homologous recombination can be damaging to cells, as it can produce chromosomal translocations and genetic abnormalities. The recombination reaction is catalyzed by enzymes known as recombinases, such as RAD51.[132] The first step in recombination is a double-stranded break caused by either an endonuclease or damage to the DNA.[133] A series of steps catalyzed in part by the recombinase then leads to joining of the two helices by at least one Holliday junction, in which a segment of a single strand in each helix is annealed to the complementary strand in the other helix. The Holliday junction is a tetrahedral junction structure that can be moved along the pair of chromosomes, swapping one strand for another. The recombination reaction is then halted by cleavage of the junction and re-ligation of the released DNA.[134] Only strands of like polarity exchange DNA during recombination. There are two types of cleavage: east-west cleavage and north-south cleavage. The north-south cleavage nicks both strands of DNA, while the east-west cleavage has one strand of DNA intact. The formation of a Holliday junction during recombination makes it possible for genetic diversity, genes to exchange on chromosomes, and expression of wild-type viral genomes.


Further information: RNA world hypothesis

DNA contains the genetic information that allows all forms of life to function, grow and reproduce. However, it is unclear how long in the 4-billion-year history of life DNA has performed this function, as it has been proposed that the earliest forms of life may have used RNA as their genetic material.[135][136] RNA may have acted as the central part of early cell metabolism as it can both transmit genetic information and carry out catalysis as part of ribozymes.[137] This ancient RNA world where nucleic acid would have been used for both catalysis and genetics may have influenced the evolution of the current genetic code based on four nucleotide bases. This would occur, since the number of different bases in such an organism is a trade-off between a small number of bases increasing replication accuracy and a large number of bases increasing the catalytic efficiency of ribozymes.[138] However, there is no direct evidence of ancient genetic systems, as recovery of DNA from most fossils is impossible because DNA survives in the environment for less than one million years, and slowly degrades into short fragments in solution.[139] Claims for older DNA have been made, most notably a report of the isolation of a viable bacterium from a salt crystal 250 million years old,[140] but these claims are controversial.[141][142]

Building blocks of DNA (adenineguanine, and related organic molecules) may have been formed extraterrestrially in outer space.[143][144][145] Complex DNA and RNA organic compounds of life, including uracilcytosine, and thymine, have also been formed in the laboratory under conditions mimicking those found in outer space, using starting chemicals, such as pyrimidine, found in meteorites. Pyrimidine, like polycyclic aromatic hydrocarbons (PAHs), the most carbon-rich chemical found in the universe, may have been formed in red giants or in interstellar cosmic dust and gas clouds.[146]

Uses in technology

Genetic engineering

Further information: Molecular biologyNucleic acid methods, and Genetic engineering

Methods have been developed to purify DNA from organisms, such as phenol-chloroform extraction, and to manipulate it in the laboratory, such as restriction digests and the polymerase chain reaction. Modern biology and biochemistry make intensive use of these techniques in recombinant DNA technology. Recombinant DNA is a man-made DNA sequence that has been assembled from other DNA sequences. They can be transformed into organisms in the form of plasmids or in the appropriate format, by using a viral vector.[147] The genetically modified organisms produced can be used to produce products such as recombinant proteins, used in medical research,[148] or be grown in agriculture.[149][150]

DNA profiling

Further information: DNA profiling

Forensic scientists can use DNA in bloodsemenskinsaliva or hair found at a crime scene to identify a matching DNA of an individual, such as a perpetrator.[151] This process is formally termed DNA profiling, also called DNA fingerprinting. In DNA profiling, the lengths of variable sections of repetitive DNA, such as short tandem repeats and minisatellites, are compared between people. This method is usually an extremely reliable technique for identifying a matching DNA.[152] However, identification can be complicated if the scene is contaminated with DNA from several people.[153] DNA profiling was developed in 1984 by British geneticist Sir Alec Jeffreys,[154] and first used in forensic science to convict Colin Pitchfork in the 1988 Enderby murders case.[155]

The development of forensic science and the ability to now obtain genetic matching on minute samples of blood, skin, saliva, or hair has led to re-examining many cases. Evidence can now be uncovered that was scientifically impossible at the time of the original examination. Combined with the removal of the double jeopardy law in some places, this can allow cases to be reopened where prior trials have failed to produce sufficient evidence to convince a jury. People charged with serious crimes may be required to provide a sample of DNA for matching purposes. The most obvious defense to DNA matches obtained forensically is to claim that cross-contamination of evidence has occurred. This has resulted in meticulous strict handling procedures with new cases of serious crime.

DNA profiling is also used successfully to positively identify victims of mass casualty incidents,[156] bodies or body parts in serious accidents, and individual victims in mass war graves, via matching to family members.

DNA profiling is also used in DNA paternity testing to determine if someone is the biological parent or grandparent of a child with the probability of parentage is typically 99.99% when the alleged parent is biologically related to the child. Normal DNA sequencing methods happen after birth, but there are new methods to test paternity while a mother is still pregnant.[157]

DNA enzymes or catalytic DNA

Further information: Deoxyribozyme

Deoxyribozymes, also called DNAzymes or catalytic DNA, were first discovered in 1994.[158] They are mostly single stranded DNA sequences isolated from a large pool of random DNA sequences through a combinatorial approach called in vitro selection or systematic evolution of ligands by exponential enrichment (SELEX). DNAzymes catalyze variety of chemical reactions including RNA-DNA cleavage, RNA-DNA ligation, amino acids phosphorylation-dephosphorylation, carbon-carbon bond formation, and etc. DNAzymes can enhance catalytic rate of chemical reactions up to 100,000,000,000-fold over the uncatalyzed reaction.[159] The most extensively studied class of DNAzymes is RNA-cleaving types which have been used to detect different metal ions and designing therapeutic agents. Several metal-specific DNAzymes have been reported including the GR-5 DNAzyme (lead-specific),[158] the CA1-3 DNAzymes (copper-specific),[160] the 39E DNAzyme (uranyl-specific) and the NaA43 DNAzyme (sodium-specific).[161] The NaA43 DNAzyme, which is reported to be more than 10,000-fold selective for sodium over other metal ions, was used to make a real-time sodium sensor in cells.


Further information: Bioinformatics

Bioinformatics involves the development of techniques to store, data mine, search and manipulate biological data, including DNA nucleic acid sequence data. These have led to widely applied advances in computer science, especially string searching algorithmsmachine learning, and database theory.[162] String searching or matching algorithms, which find an occurrence of a sequence of letters inside a larger sequence of letters, were developed to search for specific sequences of nucleotides.[163] The DNA sequence may be aligned with other DNA sequences to identify homologous sequences and locate the specific mutations that make them distinct. These techniques, especially multiple sequence alignment, are used in studying phylogenetic relationships and protein function.[164] Data sets representing entire genomes’ worth of DNA sequences, such as those produced by the Human Genome Project, are difficult to use without the annotations that identify the locations of genes and regulatory elements on each chromosome. Regions of DNA sequence that have the characteristic patterns associated with protein- or RNA-coding genes can be identified by gene finding algorithms, which allow researchers to predict the presence of particular gene products and their possible functions in an organism even before they have been isolated experimentally.[165] Entire genomes may also be compared, which can shed light on the evolutionary history of particular organism and permit the examination of complex evolutionary events.

DNA nanotechnology

The DNA structure at left (schematic shown) will self-assemble into the structure visualized by atomic force microscopy at right. DNA nanotechnology is the field that seeks to design nanoscale structures using the molecular recognition properties of DNA molecules. Image from Strong, 2004.Further information: DNA nanotechnology

DNA nanotechnology uses the unique molecular recognition properties of DNA and other nucleic acids to create self-assembling branched DNA complexes with useful properties.[166] DNA is thus used as a structural material rather than as a carrier of biological information. This has led to the creation of two-dimensional periodic lattices (both tile-based and using the DNA origami method) and three-dimensional structures in the shapes of polyhedra.[167] Nanomechanical devices and algorithmic self-assembly have also been demonstrated,[168] and these DNA structures have been used to template the arrangement of other molecules such as gold nanoparticles and streptavidin proteins.[169]

History and anthropology

Further information: Phylogenetics and Genetic genealogy

Because DNA collects mutations over time, which are then inherited, it contains historical information, and, by comparing DNA sequences, geneticists can infer the evolutionary history of organisms, their phylogeny.[170] This field of phylogenetics is a powerful tool in evolutionary biology. If DNA sequences within a species are compared, population geneticists can learn the history of particular populations. This can be used in studies ranging from ecological genetics to anthropology.

Information storage

Main article: DNA digital data storage

DNA as a storage device for information has enormous potential since it has much higher storage density compared to electronic devices. However high costs, extremely slow read and write times (memory latency), and insufficient reliability has prevented its practical use.[171][172]


Further information: History of molecular biologyJames Watson and Francis Crick (right), co-originators of the double-helix model, with Maclyn McCarty (left)Pencil sketch of the DNA double helix by Francis Crick in 1953

DNA was first isolated by the Swiss physician Friedrich Miescher who, in 1869, discovered a microscopic substance in the pus of discarded surgical bandages. As it resided in the nuclei of cells, he called it “nuclein”.[173][174] In 1878, Albrecht Kossel isolated the non-protein component of “nuclein”, nucleic acid, and later isolated its five primary nucleobases.[175][176]

In 1909, Phoebus Levene identified the base, sugar, and phosphate nucleotide unit of the RNA (then named “yeast nucleic acid”).[177][178][179] In 1929, Levene identified deoxyribose sugar in “thymus nucleic acid” (DNA).[180] Levene suggested that DNA consisted of a string of four nucleotide units linked together through the phosphate groups (“tetranucleotide hypothesis”). Levene thought the chain was short and the bases repeated in a fixed order. In 1927, Nikolai Koltsov proposed that inherited traits would be inherited via a “giant hereditary molecule” made up of “two mirror strands that would replicate in a semi-conservative fashion using each strand as a template”.[181][182] In 1928, Frederick Griffith in his experiment discovered that traits of the “smooth” form of Pneumococcus could be transferred to the “rough” form of the same bacteria by mixing killed “smooth” bacteria with the live “rough” form.[183][184] This system provided the first clear suggestion that DNA carries genetic information.

In 1933, while studying virgin sea urchin eggs, Jean Brachet suggested that DNA is found in the cell nucleus and that RNA is present exclusively in the cytoplasm. At the time, “yeast nucleic acid” (RNA) was thought to occur only in plants, while “thymus nucleic acid” (DNA) only in animals. The latter was thought to be a tetramer, with the function of buffering cellular pH.[185][186]

In 1937, William Astbury produced the first X-ray diffraction patterns that showed that DNA had a regular structure.[187]

In 1943, Oswald Avery, along with co-workers Colin MacLeod and Maclyn McCarty, identified DNA as the transforming principle, supporting Griffith’s suggestion (Avery–MacLeod–McCarty experiment).[188] DNA’s role in heredity was confirmed in 1952 when Alfred Hershey and Martha Chase in the Hershey–Chase experiment showed that DNA is the genetic material of the enterobacteria phage T2.[189]blue plaque outside The Eaglepub commemorating Crick and Watson

Late in 1951, Francis Crick started working with James Watson at the Cavendish Laboratory within the University of Cambridge. In February 1953, Linus Pauling and Robert Corey proposed a model for nucleic acids containing three intertwined chains, with the phosphates near the axis, and the bases on the outside.[190] In May 1952, Raymond Gosling a graduate student working under the supervision of Rosalind Franklin took an X-ray diffraction image, labeled as “Photo 51“,[191] at high hydration levels of DNA. This photo was given to Watson and Crick by Maurice Wilkins and was critical to their obtaining the correct structure of DNA. Franklin told Crick and Watson that the backbones had to be on the outside. Before then, Linus Pauling, and Watson and Crick, had erroneous models with the chains inside and the bases pointing outwards. Her identification of the space group for DNA crystals revealed to Crick that the two DNA strands were antiparallel.[192]

In February 1953, Watson and Crick completed their model, which is now accepted as the first correct model of the double-helix of DNA. On 28 February 1953 Crick interrupted patrons’ lunchtime at The Eagle pub in Cambridge to announce that he and Watson had “discovered the secret of life”.[193]

In the 25 April 1953 issue of the journal Nature, were published a series of five articles giving the Watson and Crick double-helix structure DNA, and evidence supporting it.[194] The structure was reported in a letter titled “MOLECULAR STRUCTURE OF NUCLEIC ACIDS A Structure for Deoxyribose Nucleic Acid“, in which they said, “It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.”[10] Followed by a letter from Franklin and Gosling, which was the first publication of their own X-ray diffraction data, and of their original analysis method.[43][195] Then followed a letter by Wilkins, and two of his colleagues, which contained an analysis of in vivo B-DNA X-ray patterns, and supported the presence in vivo of the Watson and Crick structure.[44]

In 1962, after Franklin’s death, Watson, Crick, and Wilkins jointly received the Nobel Prize in Physiology or Medicine.[196] Nobel Prizes are awarded only to living recipients. A debate continues about who should receive credit for the discovery.[197]

In an influential presentation in 1957, Crick laid out the central dogma of molecular biology, which foretold the relationship between DNA, RNA, and proteins, and articulated the “adaptor hypothesis”.[198] Final confirmation of the replication mechanism that was implied by the double-helical structure followed in 1958 through the Meselson–Stahl experiment.[199] Further work by Crick and co-workers showed that the genetic code was based on non-overlapping triplets of bases, called codons, allowing Har Gobind KhoranaRobert W. Holley, and Marshall Warren Nirenberg to decipher the genetic code.[200] These findings represent the birth of molecular biology.[201]

See also


  1. ^ “deoxyribonucleic acid”Merriam-Webster Dictionary.
  2. ^ Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P (2014). Molecular Biology of the Cell (6th ed.). Garland. p. Chapter 4: DNA, Chromosomes and Genomes. ISBN 978-0-8153-4432-2Archived from the original on 14 July 2014.
  3. ^ Purcell A. “DNA”Basic BiologyArchived from the original on 5 January 2017.
  4. ^ “Uracil” Retrieved 21 November 2019.
  5. ^ Russell P (2001). iGenetics. New York: Benjamin Cummings. ISBN 0-8053-4553-1.
  6. ^ Mashaghi A, Katan A (2013). “A physicist’s view of DNA”. De Physicus24e (3): 59–61. arXiv:1311.2545v1Bibcode:2013arXiv1311.2545M.
  7. ^ Saenger W (1984). Principles of Nucleic Acid Structure. New York: Springer-Verlag. ISBN 0-387-90762-9.
  8. Jump up to:a b Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Peter W (2002). Molecular Biology of the Cell (Fourth ed.). New York and London: Garland Science. ISBN 0-8153-3218-1OCLC 145080076Archived from the original on 1 November 2016.
  9. ^ Irobalieva RN, Fogg JM, Catanese DJ, Catanese DJ, Sutthibutpong T, Chen M, Barker AK, Ludtke SJ, Harris SA, Schmid MF, Chiu W, Zechiedrich L (October 2015). “Structural diversity of supercoiled DNA”Nature Communications6: 8440. Bibcode:2015NatCo…6.8440Idoi:10.1038/ncomms9440PMC 4608029PMID 26455586.
  10. Jump up to:a b c d Watson JD, Crick FH (April 1953). “Molecular structure of nucleic acids; a structure for deoxyribose nucleic acid” (PDF). Nature171 (4356): 737–38. Bibcode:1953Natur.171..737Wdoi:10.1038/171737a0PMID 13054692Archived (PDF)from the original on 4 February 2007.
  11. ^ Mandelkern M, Elias JG, Eden D, Crothers DM (October 1981). “The dimensions of DNA in solution”. Journal of Molecular Biology152 (1): 153–61. doi:10.1016/0022-2836(81)90099-1PMID 7338906.
  12. ^ Gregory SG, Barlow KF, McLay KE, Kaul R, Swarbreck D, Dunham A, et al. (May 2006). “The DNA sequence and biological annotation of human chromosome 1”. Nature441 (7091): 315–21. Bibcode:2006Natur.441..315Gdoi:10.1038/nature04727PMID 16710414.
  13. Jump up to:a b c Berg J, Tymoczko J, Stryer L (2002). Biochemistry. W.H. Freeman and Company. ISBN 0-7167-4955-6.
  14. ^ IUPAC-IUB Commission on Biochemical Nomenclature (CBN) (December 1970). “Abbreviations and Symbols for Nucleic Acids, Polynucleotides and their Constituents. Recommendations 1970”The Biochemical Journal120 (3): 449–54. doi:10.1042/bj1200449PMC 1179624PMID 5499957. Archived from the original on 5 February 2007.
  15. Jump up to:a b Ghosh A, Bansal M (April 2003). “A glossary of DNA structures from A to Z”. Acta Crystallographica Section D59 (Pt 4): 620–26. doi:10.1107/S0907444903003251PMID 12657780.
  16. ^ Created from PDB 1D65
  17. ^ Yakovchuk P, Protozanova E, Frank-Kamenetskii MD (2006). “Base-stacking and base-pairing contributions into thermal stability of the DNA double helix”Nucleic Acids Research34 (2): 564–74. doi:10.1093/nar/gkj454PMC 1360284PMID 16449200.
  18. ^ Tropp BE (2012). Molecular Biology (4th ed.). Sudbury, Mass.: Jones and Barlett Learning. ISBN 978-0-7637-8663-2.
  19. ^ Carr S (1953). “Watson-Crick Structure of DNA”. Memorial University of Newfoundland. Archived from the original on 19 July 2016. Retrieved 13 July 2016.
  20. ^ Verma S, Eckstein F (1998). “Modified oligonucleotides: synthesis and strategy for users”. Annual Review of Biochemistry67: 99–134. doi:10.1146/annurev.biochem.67.1.99PMID 9759484.
  21. ^ Johnson TB, Coghill RD (1925). “Pyrimidines. CIII. The discovery of 5-methylcytosine in tuberculinic acid, the nucleic acid of the tubercle bacillus”. Journal of the American Chemical Society47: 2838–44. doi:10.1021/ja01688a030.
  22. ^ Weigele P, Raleigh EA (October 2016). “Biosynthesis and Function of Modified Bases in Bacteria and Their Viruses”. Chemical Reviews116 (20): 12655–12687. doi:10.1021/acs.chemrev.6b00114PMID 27319741.
  23. ^ Kumar S, Chinnusamy V, Mohapatra T (2018). “Epigenetics of Modified DNA Bases: 5-Methylcytosine and Beyond”Frontiers in Genetics9: 640. doi:10.3389/fgene.2018.00640PMC 6305559PMID 30619465.
  24. ^ Carell T, Kurz MQ, Müller M, Rossa M, Spada F (April 2018). “Non-canonical Bases in the Genome: The Regulatory Information Layer in DNA”. Angewandte Chemie57 (16): 4296–4312. doi:10.1002/anie.201708228PMID 28941008.
  25. ^ Wing R, Drew H, Takano T, Broka C, Tanaka S, Itakura K, Dickerson RE (October 1980). “Crystal structure analysis of a complete turn of B-DNA”. Nature287 (5784): 755–58. Bibcode:1980Natur.287..755Wdoi:10.1038/287755a0PMID 7432492.
  26. Jump up to:a b Pabo CO, Sauer RT (1984). “Protein-DNA recognition”. Annual Review of Biochemistry53: 293–321. doi:10.1146/ 6236744.
  27. ^ Nikolova EN, Zhou H, Gottardo FL, Alvey HS, Kimsey IJ, Al-Hashimi HM (2013). “A historical account of Hoogsteen base-pairs in duplex DNA”Biopolymers99 (12): 955–68. doi:10.1002/bip.22334PMC 3844552PMID 23818176.
  28. ^ Clausen-Schaumann H, Rief M, Tolksdorf C, Gaub HE (April 2000). “Mechanical stability of single DNA molecules”Biophysical Journal78 (4): 1997–2007. Bibcode:2000BpJ….78.1997Cdoi:10.1016/S0006-3495(00)76747-6PMC 1300792PMID 10733978.
  29. ^ Chalikian TV, Völker J, Plum GE, Breslauer KJ (July 1999). “A more unified picture for the thermodynamics of nucleic acid duplex melting: a characterization by calorimetric and volumetric techniques”Proceedings of the National Academy of Sciences of the United States of America96 (14): 7853–58. Bibcode:1999PNAS…96.7853Cdoi:10.1073/pnas.96.14.7853PMC 22151PMID 10393911.
  30. ^ deHaseth PL, Helmann JD (June 1995). “Open complex formation by Escherichia coli RNA polymerase: the mechanism of polymerase-induced strand separation of double helical DNA”. Molecular Microbiology16 (5): 817–24. doi:10.1111/j.1365-2958.1995.tb02309.xPMID 7476180.
  31. ^ Isaksson J, Acharya S, Barman J, Cheruku P, Chattopadhyaya J (December 2004). “Single-stranded adenine-rich DNA and RNA retain structural characteristics of their respective double-stranded conformations and show directional differences in stacking pattern” (PDF). Biochemistry43 (51): 15996–6010. doi:10.1021/bi048221vPMID 15609994Archived (PDF)from the original on 10 June 2007.
  32. ^ Designation of the two strands of DNA Archived 24 April 2008 at the Wayback Machine JCBN/NC-IUB Newsletter 1989. Retrieved 7 May 2008
  33. ^ Hüttenhofer A, Schattner P, Polacek N (May 2005). “Non-coding RNAs: hope or hype?”. Trends in Genetics21 (5): 289–97. doi:10.1016/j.tig.2005.03.007PMID 15851066.
  34. ^ Munroe SH (November 2004). “Diversity of antisense regulation in eukaryotes: multiple mechanisms, emerging patterns”. Journal of Cellular Biochemistry93 (4): 664–71. doi:10.1002/jcb.20252PMID 15389973.
  35. ^ Makalowska I, Lin CF, Makalowski W (February 2005). “Overlapping genes in vertebrate genomes”. Computational Biology and Chemistry29 (1): 1–12. doi:10.1016/j.compbiolchem.2004.12.006PMID 15680581.
  36. ^ Johnson ZI, Chisholm SW (November 2004). “Properties of overlapping genes are conserved across microbial genomes”Genome Research14 (11): 2268–72. doi:10.1101/gr.2433104PMC 525685PMID 15520290.
  37. ^ Lamb RA, Horvath CM (August 1991). “Diversity of coding strategies in influenza viruses”. Trends in Genetics7 (8): 261–66. doi:10.1016/0168-9525(91)90326-LPMID 1771674.
  38. ^ Benham CJ, Mielke SP (2005). “DNA mechanics”Annual Review of Biomedical Engineering7: 21–53. doi:10.1146/annurev.bioeng.6.062403.132016PMID 16004565.
  39. Jump up to:a b Champoux JJ (2001). “DNA topoisomerases: structure, function, and mechanism”Annual Review of Biochemistry70: 369–413. doi:10.1146/annurev.biochem.70.1.369PMID 11395412.
  40. Jump up to:a b Wang JC (June 2002). “Cellular roles of DNA topoisomerases: a molecular perspective”. Nature Reviews Molecular Cell Biology3(6): 430–40. doi:10.1038/nrm831PMID 12042765.
  41. ^ Basu HS, Feuerstein BG, Zarling DA, Shafer RH, Marton LJ (October 1988). “Recognition of Z-RNA and Z-DNA determinants by polyamines in solution: experimental and theoretical studies”. Journal of Biomolecular Structure & Dynamics6 (2): 299–309. doi:10.1080/07391102.1988.10507714PMID 2482766.
  42. ^ Franklin RE, Gosling RG (6 March 1953). “The Structure of Sodium Thymonucleate Fibres I. The Influence of Water Content” (PDF). Acta Crystallogr6 (8–9): 673–77. doi:10.1107/S0365110X53001939Archived (PDF) from the original on 9 January 2016.
    Franklin RE, Gosling RG (1953). “The structure of sodium thymonucleate fibres. II. The cylindrically symmetrical Patterson function” (PDF). Acta Crystallogr6 (8–9): 678–85. doi:10.1107/S0365110X53001940.
  43. Jump up to:a b Franklin RE, Gosling RG (April 1953). “Molecular configuration in sodium thymonucleate” (PDF). Nature171(4356): 740–41. Bibcode:1953Natur.171..740Fdoi:10.1038/171740a0PMID 13054694Archived (PDF)from the original on 3 January 2011.
  44. Jump up to:a b Wilkins MH, Stokes AR, Wilson HR (April 1953). “Molecular structure of deoxypentose nucleic acids” (PDF). Nature171(4356): 738–40. Bibcode:1953Natur.171..738Wdoi:10.1038/171738a0PMID 13054693Archived (PDF)from the original on 13 May 2011.
  45. ^ Leslie AG, Arnott S, Chandrasekaran R, Ratliff RL (October 1980). “Polymorphism of DNA double helices”. Journal of Molecular Biology143 (1): 49–72. doi:10.1016/0022-2836(80)90124-2PMID 7441761.
  46. ^ Baianu IC (1980). “Structural Order and Partial Disorder in Biological systems”Bull. Math. Biol42 (4): 137–41. doi:10.1007/BF02462372.
  47. ^ Hosemann R, Bagchi RN (1962). Direct analysis of diffraction by matter. Amsterdam – New York: North-Holland Publishers.
  48. ^ Baianu IC (1978). “X-ray scattering by partially disordered membrane systems” (PDF). Acta Crystallogr A34 (5): 751–53. Bibcode:1978AcCrA..34..751Bdoi:10.1107/S0567739478001540.
  49. ^ Wahl MC, Sundaralingam M (1997). “Crystal structures of A-DNA duplexes”. Biopolymers44 (1): 45–63. doi:10.1002/(SICI)1097-0282(1997)44:1<45::AID-BIP4>3.0.CO;2-#PMID 9097733.
  50. ^ Lu XJ, Shakked Z, Olson WK (July 2000). “A-form conformational motifs in ligand-bound DNA structures”. Journal of Molecular Biology300 (4): 819–40. doi:10.1006/jmbi.2000.3690PMID 10891271.
  51. ^ Rothenburg S, Koch-Nolte F, Haag F (December 2001). “DNA methylation and Z-DNA formation as mediators of quantitative differences in the expression of alleles”. Immunological Reviews184: 286–98. doi:10.1034/j.1600-065x.2001.1840125.xPMID 12086319.
  52. ^ Oh DB, Kim YG, Rich A (December 2002). “Z-DNA-binding proteins can act as potent effectors of gene expression in vivo”Proceedings of the National Academy of Sciences of the United States of America99 (26): 16666–71. Bibcode:2002PNAS…9916666Odoi:10.1073/pnas.262672699PMC 139201PMID 12486233.
  53. Jump up to:a b Palmer J (2 December 2010). “Arsenic-loving bacteria may help in hunt for alien life”BBC NewsArchived from the original on 3 December 2010. Retrieved 2 December 2010.
  54. Jump up to:a b Bortman, Henry (2 December 2010). “Arsenic-Eating Bacteria Opens New Possibilities for Alien Life”Space.comArchivedfrom the original on 4 December 2010. Retrieved 2 December2010.
  55. ^ Katsnelson A (2 December 2010). “Arsenic-eating microbe may redefine chemistry of life”Nature Newsdoi:10.1038/news.2010.645Archived from the original on 12 February 2012.
  56. ^ Cressey D (3 October 2012). “‘Arsenic-life’ Bacterium Prefers Phosphorus after all”. Nature Newsdoi:10.1038/nature.2012.11520.
  57. Jump up to:a b Greider CW, Blackburn EH (December 1985). “Identification of a specific telomere terminal transferase activity in Tetrahymena extracts”. Cell43 (2 Pt 1): 405–13. doi:10.1016/0092-8674(85)90170-9PMID 3907856.
  58. Jump up to:a b c Nugent CI, Lundblad V (April 1998). “The telomerase reverse transcriptase: components and regulation”. Genes & Development12 (8): 1073–85. doi:10.1101/gad.12.8.1073PMID 9553037.
  59. ^ Wright WE, Tesmer VM, Huffman KE, Levene SD, Shay JW (November 1997). “Normal human chromosomes have long G-rich telomeric overhangs at one end”Genes & Development11(21): 2801–09. doi:10.1101/gad.11.21.2801PMC 316649PMID 9353250.
  60. ^ Created from Archived 17 October 2016 at the Wayback Machine
  61. Jump up to:a b Burge S, Parkinson GN, Hazel P, Todd AK, Neidle S (2006). “Quadruplex DNA: sequence, topology and structure”Nucleic Acids Research34 (19): 5402–15. doi:10.1093/nar/gkl655PMC 1636468PMID 17012276.
  62. ^ Parkinson GN, Lee MP, Neidle S (June 2002). “Crystal structure of parallel quadruplexes from human telomeric DNA”. Nature417(6891): 876–80. Bibcode:2002Natur.417..876Pdoi:10.1038/nature755PMID 12050675.
  63. ^ Griffith JD, Comeau L, Rosenfield S, Stansel RM, Bianchi A, Moss H, de Lange T (May 1999). “Mammalian telomeres end in a large duplex loop”. Cell97 (4): 503–14. CiteSeerX 10338214.
  64. ^ Seeman NC (November 2005). “DNA enables nanoscale control of the structure of matter”Quarterly Reviews of Biophysics38(4): 363–71. doi:10.1017/S0033583505004087PMC 3478329PMID 16515737.
  65. ^ Warren M (21 February 2019). “Four new DNA letters double life’s alphabet”. Nature566 (7745): 436. Bibcode:2019Natur.566..436Wdoi:10.1038/d41586-019-00650-8PMID 30809059.
  66. ^ Hoshika S, Leal NA, Kim MJ, Kim MS, Karalkar NB, Kim HJ, et al. (22 February 2019). “Hachimoji DNA and RNA: A genetic system with eight building blocks (paywall)”Science363(6429): 884–887. doi:10.1126/science.aat0971PMC 6413494PMID 30792304.
  67. ^ Hu Q, Rosenfeld MG (2012). “Epigenetic regulation of human embryonic stem cells”Frontiers in Genetics3: 238. doi:10.3389/fgene.2012.00238PMC 3488762PMID 23133442.
  68. ^ Klose RJ, Bird AP (February 2006). “Genomic DNA methylation: the mark and its mediators”. Trends in Biochemical Sciences31(2): 89–97. doi:10.1016/j.tibs.2005.12.008PMID 16403636.
  69. ^ Bird A (January 2002). “DNA methylation patterns and epigenetic memory”. Genes & Development16 (1): 6–21. doi:10.1101/gad.947102PMID 11782440.
  70. ^ Walsh CP, Xu GL (2006). “Cytosine methylation and DNA repair”. Current Topics in Microbiology and Immunology301: 283–315. doi:10.1007/3-540-31390-7_11ISBN 3-540-29114-8PMID 16570853.
  71. ^ Kriaucionis S, Heintz N (May 2009). “The nuclear DNA base 5-hydroxymethylcytosine is present in Purkinje neurons and the brain”Science324 (5929): 929–30. Bibcode:2009Sci…324..929Kdoi:10.1126/science.1169786PMC 3263819PMID 19372393.
  72. ^ Ratel D, Ravanat JL, Berger F, Wion D (March 2006). “N6-methyladenine: the other methylated base of DNA”BioEssays28 (3): 309–15. doi:10.1002/bies.20342PMC 2754416PMID 16479578.
  73. ^ Gommers-Ampt JH, Van Leeuwen F, de Beer AL, Vliegenthart JF, Dizdaroglu M, Kowalak JA, Crain PF, Borst P (December 1993). “beta-D-glucosyl-hydroxymethyluracil: a novel modified base present in the DNA of the parasitic protozoan T. brucei”. Cell75(6): 1129–36. doi:10.1016/0092-8674(93)90322-HPMID 8261512.
  74. ^ Created from PDB 1JDG
  75. ^ Douki T, Reynaud-Angelin A, Cadet J, Sage E (August 2003). “Bipyrimidine photoproducts rather than oxidative lesions are the main type of DNA damage involved in the genotoxic effect of solar UVA radiation”. Biochemistry42 (30): 9221–26. doi:10.1021/bi034593cPMID 12885257.
  76. ^ Cadet J, Delatour T, Douki T, Gasparutto D, Pouget JP, Ravanat JL, Sauvaigo S (March 1999). “Hydroxyl radicals and DNA base damage”. Mutation Research424 (1–2): 9–21. doi:10.1016/S0027-5107(99)00004-4PMID 10064846.
  77. ^ Beckman KB, Ames BN (August 1997). “Oxidative decay of DNA”. The Journal of Biological Chemistry272 (32): 19633–36. doi:10.1074/jbc.272.32.19633PMID 9289489.
  78. ^ Valerie K, Povirk LF (September 2003). “Regulation and mechanisms of mammalian double-strand break repair”. Oncogene22 (37): 5792–812. doi:10.1038/sj.onc.1206679PMID 12947387.
  79. ^ Johnson G (28 December 2010). “Unearthing Prehistoric Tumors, and Debate”The New York TimesArchived from the original on 24 June 2017. If we lived long enough, sooner or later we all would get cancer.
  80. ^ Alberts B, Johnson A, Lewis J, et al. (2002). “The Preventable Causes of Cancer”Molecular biology of the cell (4th ed.). New York: Garland Science. ISBN 0-8153-4072-9Archived from the original on 2 January 2016. A certain irreducible background incidence of cancer is to be expected regardless of circumstances: mutations can never be absolutely avoided, because they are an inescapable consequence of fundamental limitations on the accuracy of DNA replication, as discussed in Chapter 5. If a human could live long enough, it is inevitable that at least one of his or her cells would eventually accumulate a set of mutations sufficient for cancer to develop.
  81. ^ Bernstein H, Payne CM, Bernstein C, Garewal H, Dvorak K (2008). “Cancer and aging as consequences of un-repaired DNA damage”. In Kimura H, Suzuki A (eds.). New Research on DNA Damage. New York: Nova Science Publishers. pp. 1–47. ISBN 978-1-60456-581-2Archived from the original on 25 October 2014.
  82. ^ Hoeijmakers JH (October 2009). “DNA damage, aging, and cancer”. The New England Journal of Medicine361 (15): 1475–85. doi:10.1056/NEJMra0804615PMID 19812404.
  83. ^ Freitas AA, de Magalhães JP (2011). “A review and appraisal of the DNA damage theory of ageing”. Mutation Research728 (1–2): 12–22. doi:10.1016/j.mrrev.2011.05.001PMID 21600302.
  84. ^ Ferguson LR, Denny WA (September 1991). “The genetic toxicology of acridines”. Mutation Research258 (2): 123–60. doi:10.1016/0165-1110(91)90006-HPMID 1881402.
  85. ^ Stephens TD, Bunde CJ, Fillmore BJ (June 2000). “Mechanism of action in thalidomide teratogenesis”. Biochemical Pharmacology59 (12): 1489–99. doi:10.1016/S0006-2952(99)00388-3PMID 10799645.
  86. ^ Jeffrey AM (1985). “DNA modification by chemical carcinogens”. Pharmacology & Therapeutics28 (2): 237–72. doi:10.1016/0163-7258(85)90013-0PMID 3936066.
  87. ^ Braña MF, Cacho M, Gradillas A, de Pascual-Teresa B, Ramos A (November 2001). “Intercalators as anticancer drugs”. Current Pharmaceutical Design7 (17): 1745–80. doi:10.2174/1381612013397113PMID 11562309.
  88. ^ Venter JC, Adams MD, Myers EW, Li PW, Mural RJ, Sutton GG, et al. (February 2001). “The sequence of the human genome”. Science291 (5507): 1304–51. Bibcode:2001Sci…291.1304Vdoi:10.1126/science.1058040PMID 11181995.
  89. ^ Thanbichler M, Wang SC, Shapiro L (October 2005). “The bacterial nucleoid: a highly organized and dynamic structure”. Journal of Cellular Biochemistry96 (3): 506–21. doi:10.1002/jcb.20519PMID 15988757.
  90. ^ Wolfsberg TG, McEntyre J, Schuler GD (February 2001). “Guide to the draft human genome”Nature409 (6822): 824–26. Bibcode:2001Natur.409..824Wdoi:10.1038/35057000PMID 11236998.
  91. ^ Gregory TR (January 2005). “The C-value enigma in plants and animals: a review of parallels and an appeal for partnership”Annals of Botany95 (1): 133–46. doi:10.1093/aob/mci009PMC 4246714PMID 15596463.
  92. ^ Birney E, Stamatoyannopoulos JA, Dutta A, Guigó R, Gingeras TR, Margulies EH, et al. (June 2007). “Identification and analysis of functional elements in 1% of the human genome by the ENCODE pilot project”Nature447 (7146): 799–816. Bibcode:2007Natur.447..799Bdoi:10.1038/nature05874PMC 2212820PMID 17571346.
  93. ^ Created from PDB 1MSW Archived 6 January 2008 at the Wayback Machine
  94. ^ Pidoux AL, Allshire RC (March 2005). “The role of heterochromatin in centromere function”Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences360 (1455): 569–79. doi:10.1098/rstb.2004.1611PMC 1569473PMID 15905142.
  95. ^ Harrison PM, Hegyi H, Balasubramanian S, Luscombe NM, Bertone P, Echols N, Johnson T, Gerstein M (February 2002). “Molecular fossils in the human genome: identification and analysis of the pseudogenes in chromosomes 21 and 22”Genome Research12 (2): 272–80. doi:10.1101/gr.207102PMC 155275PMID 11827946.
  96. ^ Harrison PM, Gerstein M (May 2002). “Studying genomes through the aeons: protein families, pseudogenes and proteome evolution”. Journal of Molecular Biology318 (5): 1155–74. doi:10.1016/S0022-2836(02)00109-2PMID 12083509.
  97. ^ Albà M (2001). “Replicative DNA polymerases”Genome Biology2 (1): REVIEWS3002. doi:10.1186/gb-2001-2-1-reviews3002PMC 150442PMID 11178285.
  98. ^ Tani K, Nasu M (2010). “Roles of Extracellular DNA in Bacterial Ecosystems”. In Kikuchi Y, Rykova EY (eds.). Extracellular Nucleic Acids. Springer. pp. 25–38. ISBN 978-3-642-12616-1.
  99. ^ Vlassov VV, Laktionov PP, Rykova EY (July 2007). “Extracellular nucleic acids”. BioEssays29 (7): 654–67. doi:10.1002/bies.20604PMID 17563084.
  100. ^ Finkel SE, Kolter R (November 2001). “DNA as a nutrient: novel role for bacterial competence gene homologs”Journal of Bacteriology183 (21): 6288–93. doi:10.1128/JB.183.21.6288-6293.2001PMC 100116PMID 11591672.
  101. ^ Mulcahy H, Charron-Mazenod L, Lewenza S (November 2008). “Extracellular DNA chelates cations and induces antibiotic resistance in Pseudomonas aeruginosa biofilms”PLoS Pathogens4 (11): e1000213. doi:10.1371/journal.ppat.1000213PMC 2581603PMID 19023416.
  102. ^ Berne C, Kysela DT, Brun YV (August 2010). “A bacterial extracellular DNA inhibits settling of motile progeny cells within a biofilm”Molecular Microbiology77 (4): 815–29. doi:10.1111/j.1365-2958.2010.07267.xPMC 2962764PMID 20598083.
  103. ^ Whitchurch CB, Tolker-Nielsen T, Ragas PC, Mattick JS (February 2002). “Extracellular DNA required for bacterial biofilm formation”. Science295 (5559): 1487. doi:10.1126/science.295.5559.1487PMID 11859186.
  104. ^ Hu W, Li L, Sharma S, Wang J, McHardy I, Lux R, Yang Z, He X, Gimzewski JK, Li Y, Shi W (2012). “DNA builds and strengthens the extracellular matrix in Myxococcus xanthus biofilms by interacting with exopolysaccharides”PLOS ONE7 (12): e51905. Bibcode:2012PLoSO…751905Hdoi:10.1371/journal.pone.0051905PMC 3530553PMID 23300576.
  105. ^ Hui L, Bianchi DW (February 2013). “Recent advances in the prenatal interrogation of the human fetal genome”Trends in Genetics29 (2): 84–91. doi:10.1016/j.tig.2012.10.013PMC 4378900PMID 23158400.
  106. ^ Sandman K, Pereira SL, Reeve JN (December 1998). “Diversity of prokaryotic chromosomal proteins and the origin of the nucleosome”. Cellular and Molecular Life Sciences54 (12): 1350–64. doi:10.1007/s000180050259PMID 9893710.
  107. ^ Dame RT (May 2005). “The role of nucleoid-associated proteins in the organization and compaction of bacterial chromatin”. Molecular Microbiology56 (4): 858–70. doi:10.1111/j.1365-2958.2005.04598.xPMID 15853876.
  108. ^ Luger K, Mäder AW, Richmond RK, Sargent DF, Richmond TJ (September 1997). “Crystal structure of the nucleosome core particle at 2.8 A resolution”. Nature389 (6648): 251–60. Bibcode:1997Natur.389..251Ldoi:10.1038/38444PMID 9305837.
  109. ^ Jenuwein T, Allis CD (August 2001). “Translating the histone code” (PDF). Science293 (5532): 1074–80. doi:10.1126/science.1063127PMID 11498575Archived(PDF) from the original on 8 August 2017.
  110. ^ Ito T (2003). “Nucleosome assembly and remodeling”. Current Topics in Microbiology and Immunology274: 1–22. doi:10.1007/978-3-642-55747-7_1ISBN 978-3-540-44208-0PMID 12596902.
  111. ^ Thomas JO (August 2001). “HMG1 and 2: architectural DNA-binding proteins”. Biochemical Society Transactions29 (Pt 4): 395–401. doi:10.1042/BST0290395PMID 11497996.
  112. ^ Grosschedl R, Giese K, Pagel J (March 1994). “HMG domain proteins: architectural elements in the assembly of nucleoprotein structures”. Trends in Genetics10 (3): 94–100. doi:10.1016/0168-9525(94)90232-1PMID 8178371.
  113. ^ Iftode C, Daniely Y, Borowiec JA (1999). “Replication protein A (RPA): the eukaryotic SSB”. Critical Reviews in Biochemistry and Molecular Biology34 (3): 141–80. doi:10.1080/10409239991209255PMID 10473346.
  114. ^ Created from PDB 1LMB Archived 6 January 2008 at the Wayback Machine
  115. ^ Myers LC, Kornberg RD (2000). “Mediator of transcriptional regulation”. Annual Review of Biochemistry69: 729–49. doi:10.1146/annurev.biochem.69.1.729PMID 10966474.
  116. ^ Spiegelman BM, Heinrich R (October 2004). “Biological control through regulated transcriptional coactivators”. Cell119 (2): 157–67. doi:10.1016/j.cell.2004.09.037PMID 15479634.
  117. ^ Li Z, Van Calcar S, Qu C, Cavenee WK, Zhang MQ, Ren B (July 2003). “A global transcriptional regulatory role for c-Myc in Burkitt’s lymphoma cells”Proceedings of the National Academy of Sciences of the United States of America100 (14): 8164–69. Bibcode:2003PNAS..100.8164Ldoi:10.1073/pnas.1332764100PMC 166200PMID 12808131.
  118. ^ Created from PDB 1RVA Archived 6 January 2008 at the Wayback Machine
  119. ^ Bickle TA, Krüger DH (June 1993). “Biology of DNA restriction”Microbiological Reviews57 (2): 434–50. doi:10.1128/MMBR.57.2.434-450.1993PMC 372918PMID 8336674.
  120. Jump up to:a b Doherty AJ, Suh SW (November 2000). “Structural and mechanistic conservation in DNA ligases”Nucleic Acids Research28 (21): 4051–58. doi:10.1093/nar/28.21.4051PMC 113121PMID 11058099.
  121. ^ Schoeffler AJ, Berger JM (December 2005). “Recent advances in understanding structure-function relationships in the type II topoisomerase mechanism”. Biochemical Society Transactions33(Pt 6): 1465–70. doi:10.1042/BST20051465PMID 16246147.
  122. ^ Tuteja N, Tuteja R (May 2004). “Unraveling DNA helicases. Motif, structure, mechanism and function” (PDF). European Journal of Biochemistry271 (10): 1849–63. doi:10.1111/j.1432-1033.2004.04094.xPMID 15128295.
  123. ^ Joyce CM, Steitz TA (November 1995). “Polymerase structures and function: variations on a theme?”Journal of Bacteriology177 (22): 6321–29. doi:10.1128/jb.177.22.6321-6329.1995PMC 177480PMID 7592405.
  124. ^ Hubscher U, Maga G, Spadari S (2002). “Eukaryotic DNA polymerases”Annual Review of Biochemistry71: 133–63. doi:10.1146/annurev.biochem.71.090501.150041PMID 12045093.
  125. ^ Johnson A, O’Donnell M (2005). “Cellular DNA replicases: components and dynamics at the replication fork”. Annual Review of Biochemistry74: 283–315. doi:10.1146/annurev.biochem.73.011303.073859PMID 15952889.
  126. Jump up to:a b Tarrago-Litvak L, Andréola ML, Nevinsky GA, Sarih-Cottin L, Litvak S (May 1994). “The reverse transcriptase of HIV-1: from enzymology to therapeutic intervention”. FASEB Journal8 (8): 497–503. doi:10.1096/fasebj.8.8.7514143PMID 7514143.
  127. ^ Martinez E (December 2002). “Multi-protein complexes in eukaryotic gene transcription”. Plant Molecular Biology50 (6): 925–47. doi:10.1023/A:1021258713850PMID 12516863.
  128. ^ Created from PDB 1M6G Archived 10 January 2010 at the Wayback Machine
  129. ^ Cremer T, Cremer C (April 2001). “Chromosome territories, nuclear architecture and gene regulation in mammalian cells”. Nature Reviews Genetics2 (4): 292–301. doi:10.1038/35066075PMID 11283701.
  130. ^ Pál C, Papp B, Lercher MJ (May 2006). “An integrated view of protein evolution”. Nature Reviews Genetics7 (5): 337–48. doi:10.1038/nrg1838PMID 16619049.
  131. ^ O’Driscoll M, Jeggo PA (January 2006). “The role of double-strand break repair – insights from human genetics”. Nature Reviews Genetics7 (1): 45–54. doi:10.1038/nrg1746PMID 16369571.
  132. ^ Vispé S, Defais M (October 1997). “Mammalian Rad51 protein: a RecA homologue with pleiotropic functions”. Biochimie79 (9–10): 587–92. doi:10.1016/S0300-9084(97)82007-XPMID 9466696.
  133. ^ Neale MJ, Keeney S (July 2006). “Clarifying the mechanics of DNA strand exchange in meiotic recombination”Nature442(7099): 153–58. Bibcode:2006Natur.442..153Ndoi:10.1038/nature04885PMC 5607947PMID 16838012.
  134. ^ Dickman MJ, Ingleston SM, Sedelnikova SE, Rafferty JB, Lloyd RG, Grasby JA, Hornby DP (November 2002). “The RuvABC resolvasome”European Journal of Biochemistry269 (22): 5492–501. doi:10.1046/j.1432-1033.2002.03250.xPMID 12423347.
  135. ^ Joyce GF (July 2002). “The antiquity of RNA-based evolution”. Nature418 (6894): 214–21. Bibcode:2002Natur.418..214Jdoi:10.1038/418214aPMID 12110897.
  136. ^ Orgel LE (2004). “Prebiotic chemistry and the origin of the RNA world”. Critical Reviews in Biochemistry and Molecular Biology39(2): 99–123. CiteSeerX 15217990.
  137. ^ Davenport RJ (May 2001). “Ribozymes. Making copies in the RNA world”. Science292 (5520): 1278a–1278. doi:10.1126/science.292.5520.1278aPMID 11360970.
  138. ^ Szathmáry E (April 1992). “What is the optimum size for the genetic alphabet?”Proceedings of the National Academy of Sciences of the United States of America89 (7): 2614–18. Bibcode:1992PNAS…89.2614Sdoi:10.1073/pnas.89.7.2614PMC 48712PMID 1372984.
  139. ^ Lindahl T (April 1993). “Instability and decay of the primary structure of DNA”. Nature362 (6422): 709–15. Bibcode:1993Natur.362..709Ldoi:10.1038/362709a0PMID 8469282.
  140. ^ Vreeland RH, Rosenzweig WD, Powers DW (October 2000). “Isolation of a 250 million-year-old halotolerant bacterium from a primary salt crystal”. Nature407 (6806): 897–900. Bibcode:2000Natur.407..897Vdoi:10.1038/35038060PMID 11057666.
  141. ^ Hebsgaard MB, Phillips MJ, Willerslev E (May 2005). “Geologically ancient DNA: fact or artefact?”. Trends in Microbiology13 (5): 212–20. doi:10.1016/j.tim.2005.03.010PMID 15866038.
  142. ^ Nickle DC, Learn GH, Rain MW, Mullins JI, Mittler JE (January 2002). “Curiously modern DNA for a “250 million-year-old” bacterium”. Journal of Molecular Evolution54 (1): 134–37. Bibcode:2002JMolE..54..134Ndoi:10.1007/s00239-001-0025-xPMID 11734907.
  143. ^ Callahan MP, Smith KE, Cleaves HJ, Ruzicka J, Stern JC, Glavin DP, House CH, Dworkin JP (August 2011). “Carbonaceous meteorites contain a wide range of extraterrestrial nucleobases”Proceedings of the National Academy of Sciences of the United States of America108 (34): 13995–98. Bibcode:2011PNAS..10813995Cdoi:10.1073/pnas.1106493108PMC 3161613PMID 21836052.
  144. ^ Steigerwald J (8 August 2011). “NASA Researchers: DNA Building Blocks Can Be Made in Space”NASAArchived from the original on 23 June 2015. Retrieved 10 August 2011.
  145. ^ ScienceDaily Staff (9 August 2011). “DNA Building Blocks Can Be Made in Space, NASA Evidence Suggests”ScienceDailyArchived from the original on 5 September 2011. Retrieved 9 August 2011.
  146. ^ Marlaire R (3 March 2015). “NASA Ames Reproduces the Building Blocks of Life in Laboratory”NASAArchived from the original on 5 March 2015. Retrieved 5 March 2015.
  147. ^ Goff SP, Berg P (December 1976). “Construction of hybrid viruses containing SV40 and lambda phage DNA segments and their propagation in cultured monkey cells”. Cell9 (4 PT 2): 695–705. doi:10.1016/0092-8674(76)90133-1PMID 189942.
  148. ^ Houdebine LM (2007). “Transgenic animal models in biomedical research”. Methods in Molecular Biology360: 163–202. doi:10.1385/1-59745-165-7:163ISBN 978-1-59745-165-9PMID 17172731.
  149. ^ Daniell H, Dhingra A (April 2002). “Multigene engineering: dawn of an exciting new era in biotechnology”Current Opinion in Biotechnology13 (2): 136–41. doi:10.1016/S0958-1669(02)00297-5PMC 3481857PMID 11950565.
  150. ^ Job D (November 2002). “Plant biotechnology in agriculture”. Biochimie84 (11): 1105–10. doi:10.1016/S0300-9084(02)00013-5PMID 12595138.
  151. ^ Curtis C, Hereward J (29 August 2017). “From the crime scene to the courtroom: the journey of a DNA sample”The ConversationArchived from the original on 22 October 2017. Retrieved 22 October 2017.
  152. ^ Collins A, Morton NE (June 1994). “Likelihood ratios for DNA identification”Proceedings of the National Academy of Sciences of the United States of America91 (13): 6007–11. Bibcode:1994PNAS…91.6007Cdoi:10.1073/pnas.91.13.6007PMC 44126PMID 8016106.
  153. ^ Weir BS, Triggs CM, Starling L, Stowell LI, Walsh KA, Buckleton J (March 1997). “Interpreting DNA mixtures”. Journal of Forensic Sciences42 (2): 213–22. PMID 9068179.
  154. ^ Jeffreys AJ, Wilson V, Thein SL (1985). “Individual-specific ‘fingerprints’ of human DNA”. Nature316 (6023): 76–79. Bibcode:1985Natur.316…76Jdoi:10.1038/316076a0PMID 2989708.
  155. ^ Colin Pitchfork – first murder conviction on DNA evidence also clears the prime suspect Forensic Science Service Accessed 23 December 2006
  156. ^ “DNA Identification in Mass Fatality Incidents”. National Institute of Justice. September 2006. Archived from the originalon 12 November 2006.
  157. ^ “Paternity Blood Tests That Work Early in a Pregnancy” New York Times June 20, 2012 Archived 24 June 2017 at the Wayback Machine
  158. Jump up to:a b Breaker RR, Joyce GF (December 1994). “A DNA enzyme that cleaves RNA”. Chemistry & Biology1 (4): 223–29. doi:10.1016/1074-5521(94)90014-0PMID 9383394.
  159. ^ Chandra M, Sachdeva A, Silverman SK (October 2009). “DNA-catalyzed sequence-specific hydrolysis of DNA”Nature Chemical Biology5 (10): 718–20. doi:10.1038/nchembio.201PMC 2746877PMID 19684594.
  160. ^ Carmi N, Shultz LA, Breaker RR (December 1996). “In vitro selection of self-cleaving DNAs”. Chemistry & Biology3 (12): 1039–46. doi:10.1016/S1074-5521(96)90170-2PMID 9000012.
  161. ^ Torabi SF, Wu P, McGhee CE, Chen L, Hwang K, Zheng N, Cheng J, Lu Y (May 2015). “In vitro selection of a sodium-specific DNAzyme and its application in intracellular sensing”Proceedings of the National Academy of Sciences of the United States of America112 (19): 5903–08. Bibcode:2015PNAS..112.5903Tdoi:10.1073/pnas.1420361112PMC 4434688PMID 25918425.
  162. ^ Baldi P, Brunak S (2001). Bioinformatics: The Machine Learning Approach. MIT Press. ISBN 978-0-262-02506-5OCLC 45951728.
  163. ^ Gusfield, Dan (15 January 1997). Algorithms on Strings, Trees, and Sequences: Computer Science and Computational BiologyCambridge University PressISBN 978-0-521-58519-4.
  164. ^ Sjölander K (January 2004). “Phylogenomic inference of protein molecular function: advances and challenges”. Bioinformatics20(2): 170–79. CiteSeerX 14734307.
  165. ^ Mount DM (2004). Bioinformatics: Sequence and Genome Analysis (2nd ed.). Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press. ISBN 0-87969-712-1OCLC 55106399.
  166. ^ Rothemund PW (March 2006). “Folding DNA to create nanoscale shapes and patterns” (PDF). Nature440 (7082): 297–302. Bibcode:2006Natur.440..297Rdoi:10.1038/nature04586PMID 16541064.
  167. ^ Andersen ES, Dong M, Nielsen MM, Jahn K, Subramani R, Mamdouh W, Golas MM, Sander B, Stark H, Oliveira CL, Pedersen JS, Birkedal V, Besenbacher F, Gothelf KV, Kjems J (May 2009). “Self-assembly of a nanoscale DNA box with a controllable lid”. Nature459 (7243): 73–76. Bibcode:2009Natur.459…73Adoi:10.1038/nature07971hdl:11858/00-001M-0000-0010-9362-BPMID 19424153.
  168. ^ Ishitsuka Y, Ha T (May 2009). “DNA nanotechnology: a nanomachine goes live”. Nature Nanotechnology4 (5): 281–82. Bibcode:2009NatNa…4..281Idoi:10.1038/nnano.2009.101PMID 19421208.
  169. ^ Aldaye FA, Palmer AL, Sleiman HF (September 2008). “Assembling materials with DNA as the guide”. Science321(5897): 1795–99. Bibcode:2008Sci…321.1795Adoi:10.1126/science.1154533PMID 18818351.
  170. ^ Wray GA (2002). “Dating branches on the tree of life using DNA”Genome Biology3 (1): REVIEWS0001. doi:10.1186/gb-2001-3-1-reviews0001PMC 150454PMID 11806830.
  171. ^ Panda D, Molla KA, Baig MJ, Swain A, Behera D, Dash M (May 2018). “DNA as a digital information storage device: hope or hype?”3 Biotech8 (5): 239. doi:10.1007/s13205-018-1246-7PMC 5935598PMID 29744271.
  172. ^ Akram F, Haq IU, Ali H, Laghari AT (October 2018). “Trends to store digital data in DNA: an overview”. Molecular Biology Reports45 (5): 1479–1490. doi:10.1007/s11033-018-4280-yPMID 30073589.
  173. ^ Miescher F (1871). “Ueber die chemische Zusammensetzung der Eiterzellen” [On the chemical composition of pus cells]. Medicinisch-chemische Untersuchungen (in German). 4: 441–60. Ich habe mich daher später mit meinen Versuchen an die ganzen Kerne gehalten, die Trennung der Körper, die ich einstweilen ohne weiteres Präjudiz als lösliches und unlösliches Nuclein bezeichnen will, einem günstigeren Material überlassend. (Therefore, in my experiments I subsequently limited myself to the whole nucleus, leaving to a more favorable material the separation of the substances, that for the present, without further prejudice, I will designate as soluble and insoluble nuclear material (“Nuclein”)
  174. ^ Dahm R (January 2008). “Discovering DNA: Friedrich Miescher and the early years of nucleic acid research”. Human Genetics122 (6): 565–81. doi:10.1007/s00439-007-0433-0PMID 17901982.
  175. ^ See:
    • Kossel A (1879). “Ueber Nucleïn der Hefe” [On nuclein in yeast]. Zeitschrift für physiologische Chemie (in German). 3: 284–91.
    • Kossel A (1880). “Ueber Nucleïn der Hefe II” [On nuclein in yeast, Part 2]. Zeitschrift für physiologische Chemie (in German). 4: 290–95.
    • Kossel A (1881). “Ueber die Verbreitung des Hypoxanthins im Thier- und Pflanzenreich” [On the distribution of hypoxanthins in the animal and plant kingdoms]. Zeitschrift für physiologische Chemie (in German). 5: 267–71.
    • Kossel A (1881). Trübne KJ (ed.). Untersuchungen über die Nucleine und ihre Spaltungsprodukte [Investigations into nuclein and its cleavage products] (in German). Strassburg, Germany. p. 19.
    • Kossel A (1882). “Ueber Xanthin und Hypoxanthin” [On xanthin and hypoxanthin]. Zeitschrift für physiologische Chemie6: 422–31.
    • Albrect Kossel (1883) “Zur Chemie des Zellkerns” Archived17 November 2017 at the Wayback Machine (On the chemistry of the cell nucleus), Zeitschrift für physiologische Chemie7 : 7–22.
    • Kossel A (1886). “Weitere Beiträge zur Chemie des Zellkerns” [Further contributions to the chemistry of the cell nucleus]. Zeitschrift für Physiologische Chemie (in German). 10: 248–64. On p. 264, Kossel remarked presciently: Der Erforschung der quantitativen Verhältnisse der vier stickstoffreichen Basen, der Abhängigkeit ihrer Menge von den physiologischen Zuständen der Zelle, verspricht wichtige Aufschlüsse über die elementaren physiologisch-chemischen Vorgänge. (The study of the quantitative relations of the four nitrogenous bases—[and] of the dependence of their quantity on the physiological states of the cell—promises important insights into the fundamental physiological-chemical processes.)
  176. ^ Jones ME (September 1953). “Albrecht Kossel, a biographical sketch”The Yale Journal of Biology and Medicine26 (1): 80–97. PMC 2599350PMID 13103145.
  177. ^ Levene PA, Jacobs WA (1909). “Über Inosinsäure”. Berichte der Deutschen Chemischen Gesellschaft (in German). 42: 1198–203. doi:10.1002/cber.190904201196.
  178. ^ Levene PA, Jacobs WA (1909). “Über die Hefe-Nucleinsäure”Berichte der Deutschen Chemischen Gesellschaft (in German). 42(2): 2474–78. doi:10.1002/cber.190904202148.
  179. ^ Levene P (1919). “The structure of yeast nucleic acid”. J Biol Chem40 (2): 415–24.
  180. ^ Cohen JS, Portugal FH (1974). “The search for the chemical structure of DNA” (PDF). Connecticut Medicine38 (10): 551–52, 554–57.
  181. ^ Koltsov proposed that a cell’s genetic information was encoded in a long chain of amino acids. See:
    • Кольцов, Н. К. (12 December 1927). Физико-химические основы морфологии [The physical-chemical basis of morphology] (Speech). 3rd All-Union Meeting of Zoologist, Anatomists, and Histologists (in Russian). Leningrad, U.S.S.R.
    • Reprinted in: Кольцов, Н. К. (1928). “Физико-химические основы морфологии” [The physical-chemical basis of morphology]. Успехи экспериментальной биологии (Advances in Experimental Biology) series B (in Russian). 7(1): ?.
    • Reprinted in German as: Koltzoff NK (1928). “Physikalisch-chemische Grundlagen der Morphologie” [The physical-chemical basis of morphology]. Biologisches Zentralblatt (in German). 48 (6): 345–69.
    • In 1934, Koltsov contended that the proteins that contain a cell’s genetic information replicate. See: Koltzoff N (October 1934). “The structure of the chromosomes in the salivary glands of Drosophila”. Science80 (2075): 312–13. Bibcode:1934Sci….80..312Kdoi:10.1126/science.80.2075.312PMID 17769043From page 313: “I think that the size of the chromosomes in the salivary glands [of Drosophila] is determined through the multiplication of genonemes. By this term I designate the axial thread of the chromosome, in which the geneticists locate the linear combination of genes; … In the normal chromosome there is usually only one genoneme; before cell-division this genoneme has become divided into two strands.”
  182. ^ Soyfer VN (September 2001). “The consequences of political dictatorship for Russian science”. Nature Reviews Genetics2 (9): 723–29. doi:10.1038/35088598PMID 11533721.
  183. ^ Griffith F (January 1928). “The Significance of Pneumococcal Types”The Journal of Hygiene27 (2): 113–59. doi:10.1017/S0022172400031879PMC 2167760PMID 20474956.
  184. ^ Lorenz MG, Wackernagel W (September 1994). “Bacterial gene transfer by natural genetic transformation in the environment”Microbiological Reviews58 (3): 563–602. doi:10.1128/MMBR.58.3.563-602.1994PMC 372978PMID 7968924.
  185. ^ Brachet J (1933). “Recherches sur la synthese de l’acide thymonucleique pendant le developpement de l’oeuf d’Oursin”. Archives de Biologie (in Italian). 44: 519–76.
  186. ^ Burian R (1994). “Jean Brachet’s Cytochemical Embryology: Connections with the Renovation of Biology in France?” (PDF). In Debru C, Gayon J, Picard JF (eds.). Les sciences biologiques et médicales en France 1920–1950. Cahiers pour I’histoire de la recherche. 2. Paris: CNRS Editions. pp. 207–20.
  187. ^ See:
  188. ^ Avery OT, Macleod CM, McCarty M (February 1944). “Studies on the Chemical Nature of the Substance Inducing Transformation of Pneumococcal Types: Induction of Transformation by a Desoxyribonucleic Acid Fraction Isolated from Pneumococcus Type III”The Journal of Experimental Medicine79 (2): 137–58. doi:10.1084/jem.79.2.137PMC 2135445PMID 19871359.
  189. ^ Hershey AD, Chase M (May 1952). “Independent functions of viral protein and nucleic acid in growth of bacteriophage”The Journal of General Physiology36 (1): 39–56. doi:10.1085/jgp.36.1.39PMC 2147348PMID 12981234.
  190. ^ Pauling L, Corey RB (February 1953). “A Proposed Structure For The Nucleic Acids”Proceedings of the National Academy of Sciences of the United States of America39 (2): 84–97. Bibcode:1953PNAS…39…84Pdoi:10.1073/pnas.39.2.84PMC 1063734PMID 16578429.
  191. ^ The B-DNA X-ray pattern on the right of this linked imageArchived 25 May 2012 at
  192. ^ Schwartz, James (2008). In pursuit of the gene : from Darwin to DNA. Cambridge, Mass.: Harvard University Press.
  193. ^ Regis E (2009). What Is Life?: investigating the nature of life in the age of synthetic biology. Oxford: Oxford University Press. p. 52. ISBN 978-0-19-538341-6.
  194. ^ “Double Helix of DNA: 50 Years”Nature Archives. Archived from the original on 5 April 2015.
  195. ^ “Original X-ray diffraction image”. Oregon State Library. Archived from the original on 30 January 2009. Retrieved 6 February 2011.
  196. ^ “The Nobel Prize in Physiology or Medicine 1962”
  197. ^ Maddox B (January 2003). “The double helix and the ‘wronged heroine'” (PDF). Nature421 (6921): 407–08. Bibcode:2003Natur.421..407Mdoi:10.1038/nature01399PMID 12540909Archived (PDF) from the original on 17 October 2016.
  198. ^ Crick F (1955). A Note for the RNA Tie Club (PDF) (Speech). Cambridge, England. Archived from the original (PDF) on 1 October 2008.
  199. ^ Meselson M, Stahl FW (July 1958). “The Replication of DNA in Escherichia Coli”Proceedings of the National Academy of Sciences of the United States of America44 (7): 671–82. Bibcode:1958PNAS…44..671Mdoi:10.1073/pnas.44.7.671PMC 528642PMID 16590258.
  200. ^ “The Nobel Prize in Physiology or Medicine 1968”
  201. ^ Pray L (2008). “Discovery of DNA structure and function: Watson and Crick”. Nature Education1 (1): 100.

Further reading

External links

Library resources about
Online booksResources in your libraryResources in other libraries
Wikiquote has quotations related to: DNA
Wikiversity has learning resources about DNA
Wikimedia Commons has media related to DNA.

Listen to this article (info/dl)


This audio file was created from a revision of the article “DNA” dated 2007-02-12, and does not reflect subsequent edits to the article. (Audio help)More spoken articles

showvteGene expression
showvteTypes of nucleic acids


Navigation menu




In other projects



Edit links

Skip to main content

Search form

US life expectancy on the rise for 1st time in 4 years

Fresh data from the CDC’s National Center for Health Statistics suggests U.S. life expectancy is climbing for the first time since 2014—but heart disease remains the number-one threat to mortality in the country.

By Anicka SlachtaJanuary 30, 2020

Fresh data from the CDC’s National Center for Health Statistics suggests U.S. life expectancy is climbing for the first time since 2014—but heart disease remains the number-one threat to mortality in the country.

The January report, written by Jiaquan Xu, MD, and colleagues, details the CDC’s finalized mortality statistics through 2018. At that point in time, life expectancy at birth in the United States was 78.7 years—a 0.1-point increase from 2017, when life expectancy was 78.6 years. 

Xu et al. said the 0.1-year increase in life expectancy the team noted in 2018 was likely due to significant decreases in mortality from cancer, unintentional injuries, chronic lower respiratory diseases and heart disease. The last time U.S. life expectancy was on the rise was between 2010 and 2014, when it increased by 0.2 years on average. It declined between 2014 and 2017 following the widespread damage of the opioid epidemic, and while a 0.1-point increase in 2018 helped boost those numbers, national life expectancy still lagged 0.2 years below the peak expectancy observed in 2014.

Life expectancy increased similarly between the sexes between 2017 and 2018, with men experiencing a jump from 76.1 years in 2017 to 76.2 years in 2018 and women seeing an increase from 81.1 to 81.2 years, respectively. Females have consistently lived longer than males; the difference in life expectancy between women and men was five years in both 2018 and 2017.

The age-adjusted death rate in the U.S. decreased by 1.1% between 2017 and 2018, from 731.9 deaths per 100,000 standard population in 2017 to 723.6 deaths per 100,000 in 2018. During the two-year period, age-specific death rates fell for people aged 15-24, 25-34, 45-54, 65-74, 75-84 and 85 and up.

The 10 leading causes of death in the U.S. were the same in 2018 as they were in 2017, topped by heart disease and cancer. Unintentional injuries, chronic lower respiratory diseases, stroke, Alzheimer’s, diabetes, influenza and pneumonia, kidney disease and suicide followed suit.

Xu and colleagues said around 73.8% of all deaths in the U.S. in 2018 could be attributed to at least one of the top 10 leading causes of death that year. Between 2017 and 2018, age-adjusted death rates decreased by 0.8% for heart disease, 2.2% for cancer, 2.8% for unintentional injuries, 2.9% for chronic lower respiratory diseases, 1.3% for stroke and 1.6% for Alzheimer’s disease. It’s not all good news, though—death rates increased by 4.2% for flu and pneumonia and by 1.4% for suicide.

Leading causes of death also remained uniform among children between 2017 and 2018, though infant mortality rate decreased 2.3% over the two-year period, from 579.3 infant deaths per 100,000 live births in 2017 to 566.2 deaths per 100,000 live births in 2018. 

Find the CDC’s full report online here.

© Copyright TriMed Media 2020. Interested in LINKING to or REPRINTING this content? View our policies by clicking here.

Subscribe to Cardiovascular Business News

The free daily newsletter covering the top cardiovascular headlines

By signing up you agree to our privacy policy. You can opt out anytime.

 © 2020 TriMed Media Group, Inc. All Rights Reserved. | Terms of Use | Privacy Policy


From Wikipedia, the free encyclopediaJump to navigationJump to searchFor other uses, see Innovation (disambiguation).

Innovation in its modern meaning is “a new idea, creative thoughts, new imaginations in form of device or method”.[1] Innovation is often also viewed as the application of better solutions that meet new requirements, unarticulated needs, or existing market needs.[2] Such innovation takes place through the provision of more-effective productsprocessesservicestechnologies, or business models that are made available to marketsgovernments and society. An innovation is something original and more effective and, as a consequence, new, that “breaks into” the market or society.[3] Innovation is related to, but not the same as, invention,[4] as innovation is more apt to involve the practical implementation of an invention (ie new / improved ability) to make a meaningful impact in the market or society,[5] and not all innovations require an invention. Innovation often[quantify] manifests itself via the engineering process, when the problem being solved is of a technical or scientific nature. The opposite of innovation is exnovation.

While a novel device is often described[by whom?] as an innovation, in economics, management science, and other fields of practice and analysis, innovation is generally considered to be the result of a process[6] that brings together various novel ideas in such a way that they affect society. In industrial economics, innovations are created and found[by whom?] empirically from services to meet growing consumer demand.[7][8][9]

Innovation also has an older historical meaning which is quite different. From the 1400s through the 1600s, prior to early American settlement, the concept of “innovation” was pejorative. It was an early modern synonym for rebellion, revolt and heresy.[10][11][12][13]



A 2014 survey of literature on innovation found over 40 definitions. In an industrial survey of how the software industry defined innovation, the following definition given by Crossan and Apaydin was considered to be the most complete, which builds on the Organisation for Economic Co-operation and Development (OECD) manual’s definition:[14]

Innovation is production or adoption, assimilation, and exploitation of a value-added novelty in economic and social spheres; renewal and enlargement of products, services, and markets; development of new methods of production; and the establishment of new management systems. It is both a process and an outcome.

According to Kanter, innovation includes original invention and creative use and defines innovation as a generation, admission and realization of new ideas, products, services and processes.[15]

Two main dimensions of innovation were degree of novelty (patent) (i.e. whether an innovation is new to the firm, new to the market, new to the industry, or new to the world) and kind of innovation (i.e. whether it is processor product-service system innovation).[14] In recent organizational scholarship, researchers of workplaces have also distinguished innovation to be separate from creativity, by providing an updated definition of these two related but distinct constructs:

Workplace creativity concerns the cognitive and behavioral processes applied when attempting to generate novel ideas. Workplace innovation concerns the processes applied when attempting to implement new ideas. Specifically, innovation involves some combination of problem/opportunity identification, the introduction, adoption or modification of new ideas germane to organizational needs, the promotion of these ideas, and the practical implementation of these ideas.[16]

Inter-disciplinary views[edit]

Business and economics[edit]

Main article: Innovation economics

In business and in economics, innovation can become a catalyst for growth. With rapid advancements in transportation and communications over the past few decades, the old-world concepts of factor endowments and comparative advantage which focused on an area’s unique inputs are outmoded for today’s global economy. Economist Joseph Schumpeter (1883–1950), who contributed greatly to the study of innovation economics, argued that industries must incessantly revolutionize the economic structure from within, that is innovate with better or more effective processes and products, as well as market distribution, such as the connection from the craft shop to factory. He famously asserted that “creative destruction is the essential fact about capitalism“.[17] Entrepreneurs continuously look for better ways to satisfy their consumer base with improved quality, durability, service and price which come to fruition in innovation with advanced technologies and organizational strategies.[18]

A prime example of innovation involved the explosive boom of Silicon Valley startups out of the Stanford Industrial Park. In 1957, dissatisfied employees of Shockley Semiconductor, the company of Nobel laureate and co-inventor of the transistor William Shockley, left to form an independent firm, Fairchild Semiconductor. After several years, Fairchild developed into a formidable presence in the sector. Eventually, these founders left to start their own companies based on their own, unique, latest ideas, and then leading employees started their own firms. Over the next 20 years, this snowball process launched the momentous startup-company explosion of information-technology firms. Essentially, Silicon Valley began as 65 new enterprises born out of Shockley’s eight former employees.[19] Since then, hubs of innovation have sprung up globally with similar metonyms, including Silicon Alley encompassing New York City.

Another example involves business incubators – a phenomenon nurtured by governments around the world, close to knowledge clusters (mostly research-based) like universities or other Government Excellence Centres – which aim primarily to channel generated knowledge to applied innovation outcomes in order to stimulate regional or national economic growth.[20]


In the organizational context, innovation may be linked to positive changes in efficiencyproductivityqualitycompetitiveness, and market share. However, recent research findings highlight the complementary role of organizational culture in enabling organizations to translate innovative activity into tangible performance improvements.[21] Organizations can also improve profits and performance by providing work groups opportunities and resources to innovate, in addition to employee’s core job tasks.[22] Peter Drucker wrote:

Innovation is the specific function of entrepreneurship, whether in an existing business, a public service institution, or a new venture started by a lone individual in the family kitchen. It is the means by which the entrepreneur either creates new wealth-producing resources or endows existing resources with enhanced potential for creating wealth. –Drucker[23]

According to Clayton Christensen, disruptive innovation is the key to future success in business.[24] The organization requires a proper structure in order to retain competitive advantage. It is necessary to create and nurture an environment of innovation. Executives and managers need to break away from traditional ways of thinking and use change to their advantage. It is a time of risk but even greater opportunity.[25] The world of work is changing with the increase in the use of technology and both companies and businesses are becoming increasingly competitive. Companies will have to downsize or reengineer their operations to remain competitive. This will affect employment as businesses will be forced to reduce the number of people employed while accomplishing the same amount of work if not more.[26]

While disruptive innovation will typically “attack a traditional business model with a lower-cost solution and overtake incumbent firms quickly,”[27] foundational innovation is slower, and typically has the potential to create new foundations for global technology systems over the longer term. Foundational innovation tends to transform business operating models as entirely new business models emerge over many years, with gradual and steady adoption of the innovation leading to waves of technological and institutional change that gain momentum more slowly.[27] The advent of the packet-switched communication protocol TCP/IP—originally introduced in 1972 to support a single use case for United States Department of Defense electronic communication (email), and which gained widespread adoption only in the mid-1990s with the advent of the World Wide Web—is a foundational technology.[27]

All organizations can innovate, including for example hospitals, universities, and local governments.[28] For instance, former Mayor Martin O’Malley pushed the City of Baltimore to use CitiStat, a performance-measurement data and management system that allows city officials to maintain statistics on several areas from crime trends to the conditions of potholes. This system aids in better evaluation of policies and procedures with accountability and efficiency in terms of time and money. In its first year, CitiStat saved the city $13.2 million.[29] Even mass transit systems have innovated with hybrid bus fleets to real-time tracking at bus stands. In addition, the growing use of mobile data terminals in vehicles, that serve as communication hubs between vehicles and a control center, automatically send data on location, passenger counts, engine performance, mileage and other information. This tool helps to deliver and manage transportation systems.[30]

Still other innovative strategies include hospitals digitizing medical information in electronic medical records. For example, the U.S. Department of Housing and Urban Development‘s HOPE VI initiatives turned severely distressed public housing in urban areas into revitalized, mixed-income environments; the Harlem Children’s Zone used a community-based approach to educate local area children; and the Environmental Protection Agency‘s brownfield grants facilitates turning over brownfields for environmental protectiongreen spacescommunity and commercial development.


There are several sources of innovation. It can occur as a result of a focus effort by a range of different agents, by chance, or as a result of a major system failure.

According to Peter F. Drucker, the general sources of innovations are different changes in industry structure, in market structure, in local and global demographics, in human perception, mood and meaning, in the amount of already available scientific knowledge, etc.[23]Original model of three phases of the process of Technological Change

In the simplest linear model of innovation the traditionally recognized source is manufacturer innovation. This is where an agent (person or business) innovates in order to sell the innovation. Specifically, R&D measurement is the commonly used input for innovation, in particular in the business sector, named Business Expenditure on R&D (BERD) that grew over the years on the expenses of the declining R&D invested by the public sector.[31]

Another source of innovation, only now becoming widely recognized, is end-user innovation. This is where an agent (person or company) develops an innovation for their own (personal or in-house) use because existing products do not meet their needs. MIT economist Eric von Hippel has identified end-user innovation as, by far, the most important and critical in his classic book on the subject, “The Sources of Innovation”.[32]

The robotics engineer Joseph F. Engelberger asserts that innovations require only three things:

  1. a recognized need
  2. competent people with relevant technology
  3. financial support[33]

However, innovation processes usually involve: identifying customer needs, macro and meso trends, developing competences, and finding financial support.

The Kline chain-linked model of innovation[34] places emphasis on potential market needs as drivers of the innovation process, and describes the complex and often iterative feedback loops between marketing, design, manufacturing, and R&D.

Innovation by businesses is achieved in many ways, with much attention now given to formal research and development (R&D) for “breakthrough innovations”. R&D help spur on patents and other scientific innovations that leads to productive growth in such areas as industry, medicine, engineering, and government.[35] Yet, innovations can be developed by less formal on-the-job modifications of practice, through exchange and combination of professional experience and by many other routes. Investigation of relationship between the concepts of innovation and technology transfer revealed overlap.[36] The more radical and revolutionary innovations tend to emerge from R&D, while more incremental innovations may emerge from practice – but there are many exceptions to each of these trends.

Information technology and changing business processes and management style can produce a work climate favorable to innovation.[37] For example, the software tool company Atlassian conducts quarterly “ShipIt Days” in which employees may work on anything related to the company’s products.[38] Google employees work on self-directed projects for 20% of their time (known as Innovation Time Off). Both companies cite these bottom-up processes as major sources for new products and features.

An important innovation factor includes customers buying products or using services. As a result, organizations may incorporate users in focus groups (user centred approach), work closely with so called lead users (lead user approach) or users might adapt their products themselves. The lead user method focuses on idea generation based on leading users to develop breakthrough innovations. U-STIR, a project to innovate Europe’s surface transportation system, employs such workshops.[39] Regarding this user innovation, a great deal of innovation is done by those actually implementing and using technologies and products as part of their normal activities. Sometimes user-innovators may become entrepreneurs, selling their product, they may choose to trade their innovation in exchange for other innovations, or they may be adopted by their suppliers. Nowadays, they may also choose to freely reveal their innovations, using methods like open source. In such networks of innovation the users or communities of users can further develop technologies and reinvent their social meaning.[40][41]

One technique for innovating a solution to an identified problem is to actually attempt an experiment with many possible solutions.[42] This technique was famously used by Thomas Edison’s laboratory to find a version of the incandescent light bulb economically viable for home use, which involved searching through thousands of possible filament designs before settling on carbonized bamboo.

This technique is sometimes used in pharmaceutical drug discovery. Thousands of chemical compounds are subjected to high-throughput screening to see if they have any activity against a target molecule which has been identified as biologically significant to a disease. Promising compounds can then be studied; modified to improve efficacy, reduce side effects, and reduce cost of manufacture; and if successful turned into treatments.

The related technique of A/B testing is often used to help optimize the design of web sites and mobile apps. This is used by major sites such as amazon.comFacebookGoogle, and Netflix.[43] Procter & Gamble uses computer-simulated products and online user panels to conduct larger numbers of experiments to guide the design, packaging, and shelf placement of consumer products.[44] Capital One uses this technique to drive credit card marketing offers.[43]

Goals and failures[edit]

Programs of organizational innovation are typically tightly linked to organizational goals and objectives, to the business plan, and to market competitive positioning. One driver for innovation programs in corporations is to achieve growth objectives. As Davila et al. (2006) notes, “Companies cannot grow through cost reduction and reengineering alone… Innovation is the key element in providing aggressive top-line growth, and for increasing bottom-line results”.[45]

One survey across a large number of manufacturing and services organizations found, ranked in decreasing order of popularity, that systematic programs of organizational innovation are most frequently driven by: improved quality, creation of new markets, extension of the product range, reduced labor costs, improved production processes, reduced materials, reduced environmental damage, replacement of products/services, reduced energy consumption, conformance to regulations.[45]

These goals vary between improvements to products, processes and services and dispel a popular myth that innovation deals mainly with new product development. Most of the goals could apply to any organization be it a manufacturing facility, marketing company, hospital or government. Whether innovation goals are successfully achieved or otherwise depends greatly on the environment prevailing in the organization.[46]

Conversely, failure can develop in programs of innovations. The causes of failure have been widely researched and can vary considerably. Some causes will be external to the organization and outside its influence of control. Others will be internal and ultimately within the control of the organization. Internal causes of failure can be divided into causes associated with the cultural infrastructure and causes associated with the innovation process itself. Common causes of failure within the innovation process in most organizations can be distilled into five types: poor goal definition, poor alignment of actions to goals, poor participation in teams, poor monitoring of results, poor communication and access to information.[47]



Main article: Diffusion of innovations

Diffusion of innovation research was first started in 1903 by seminal researcher Gabriel Tarde, who first plotted the S-shaped diffusion curve. Tarde defined the innovation-decision process as a series of steps that include:[48]

  1. knowledge
  2. forming an attitude
  3. a decision to adopt or reject
  4. implementation and use
  5. confirmation of the decision

Once innovation occurs, innovations may be spread from the innovator to other individuals and groups. This process has been proposed that the lifecycle of innovations can be described using the ‘s-curve‘ or diffusion curve. The s-curve maps growth of revenue or productivity against time. In the early stage of a particular innovation, growth is relatively slow as the new product establishes itself. At some point, customers begin to demand and the product growth increases more rapidly. New incremental innovations or changes to the product allow growth to continue. Towards the end of its lifecycle, growth slows and may even begin to decline. In the later stages, no amount of new investment in that product will yield a normal rate of return

The s-curve derives from an assumption that new products are likely to have “product life” – ie, a start-up phase, a rapid increase in revenue and eventual decline. In fact, the great majority of innovations never get off the bottom of the curve, and never produce normal returns.

Innovative companies will typically be working on new innovations that will eventually replace older ones. Successive s-curves will come along to replace older ones and continue to drive growth upwards. In the figure above the first curve shows a current technology. The second shows an emerging technology that currently yields lower growth but will eventually overtake current technology and lead to even greater levels of growth. The length of life will depend on many factors.[49]


Measuring innovation is inherently difficult as it implies commensurability so that comparisons can be made in quantitative terms. Innovation, however, is by definition novelty. Comparisons are thus often meaningless across products or service.[50] Nevertheless, Edison et al.[51] in their review of literature on innovation management found 232 innovation metrics. They categorized these measures along five dimensions; ie inputs to the innovation process, output from the innovation process, effect of the innovation output, measures to access the activities in an innovation process and availability of factors that facilitate such a process.[51]

There are two different types of measures for innovation: the organizational level and the political level.

Organizational level[edit]

The measure of innovation at the organizational level relates to individuals, team-level assessments, and private companies from the smallest to the largest company. Measure of innovation for organizations can be conducted by surveys, workshops, consultants, or internal benchmarking. There is today no established general way to measure organizational innovation. Corporate measurements are generally structured around balanced scorecards which cover several aspects of innovation such as business measures related to finances, innovation process efficiency, employees’ contribution and motivation, as well benefits for customers. Measured values will vary widely between businesses, covering for example new product revenue, spending in R&D, time to market, customer and employee perception & satisfaction, number of patents, additional sales resulting from past innovations.[52]

Political level[edit]

For the political level, measures of innovation are more focused on a country or region competitive advantage through innovation. In this context, organizational capabilities can be evaluated through various evaluation frameworks, such as those of the European Foundation for Quality Management. The OECD Oslo Manual (1992) suggests standard guidelines on measuring technological product and process innovation. Some people consider the Oslo Manual complementary to the Frascati Manual from 1963. The new Oslo Manual from 2018 takes a wider perspective to innovation, and includes marketing and organizational innovation. These standards are used for example in the European Community Innovation Surveys.[53]

Other ways of measuring innovation have traditionally been expenditure, for example, investment in R&D (Research and Development) as percentage of GNP (Gross National Product). Whether this is a good measurement of innovation has been widely discussed and the Oslo Manual has incorporated some of the critique against earlier methods of measuring. The traditional methods of measuring still inform many policy decisions. The EU Lisbon Strategy has set as a goal that their average expenditure on R&D should be 3% of GDP.[54]


Many scholars claim that there is a great bias towards the “science and technology mode” (S&T-mode or STI-mode), while the “learning by doing, using and interacting mode” (DUI-mode) is ignored and measurements and research about it rarely done. For example, an institution may be high tech with the latest equipment, but lacks crucial doing, using and interacting tasks important for innovation.[citation needed]

A common industry view (unsupported by empirical evidence) is that comparative cost-effectiveness research is a form of price control which reduces returns to industry, and thus limits R&D expenditure, stifles future innovation and compromises new products access to markets.[55] Some academics claim cost-effectiveness research is a valuable value-based measure of innovation which accords “truly significant” therapeutic advances (ie providing “health gain”) higher prices than free market mechanisms.[56] Such value-based pricing has been viewed as a means of indicating to industry the type of innovation that should be rewarded from the public purse.[57]

An Australian academic developed the case that national comparative cost-effectiveness analysis systems should be viewed as measuring “health innovation” as an evidence-based policy concept for valuing innovation distinct from valuing through competitive markets, a method which requires strong anti-trust laws to be effective, on the basis that both methods of assessing pharmaceutical innovations are mentioned in annex 2C.1 of the Australia-United States Free Trade Agreement.[58][59][60]


Several indices attempt to measure innovation and rank entities based on these measures, such as:


Many research studies try to rank countries based on measures of innovation. Common areas of focus include: high-tech companies, manufacturingpatentspost secondary educationresearch and development, and research personnel. The left ranking of the top 10 countries below is based on the 2016 Bloomberg Innovation Index.[71] However, studies may vary widely; for example the Global Innovation Index 2016 ranks Switzerland as number one wherein countries like South Korea and Japan do not even make the top ten.[72]

1 South Korea87.38
2 Germany87.3
3 Finland85.57
4  Switzerland85.49
5 Israel84.78
6 Singapore84.49
7 Sweden84.15
8 United States83.21
9 Japan81.40
10 France81.67
1  Switzerland67.24
2 Sweden63.65
3 United States61.73
4 Netherlands61.44
5 United Kingdom61.30
6 Finland59.83
7 Denmark58.44
8 Singapore58.37
9 Germany58.19
10 Israel57.43
1 Singapore73
2  Switzerland72
3 Belgium59
4 Germany55
5 Sweden54
6 United States52
7 United Kingdom52
8 Denmark51
9 Ireland51
10 South Korea51


In 2005 Jonathan Huebner, a physicist working at the Pentagon‘s Naval Air Warfare Center, argued on the basis of both U.S. patents and world technological breakthroughs, per capita, that the rate of human technological innovation peaked in 1873 and has been slowing ever since.[76][77] In his article, he asked “Will the level of technology reach a maximum and then decline as in the Dark Ages?”[76] In later comments to New Scientist magazine, Huebner clarified that while he believed that we will reach a rate of innovation in 2024 equivalent to that of the Dark Ages, he was not predicting the reoccurrence of the Dark Ages themselves.[78]

John Smart criticized the claim and asserted that technological singularity researcher Ray Kurzweil and others showed a “clear trend of acceleration, not deceleration” when it came to innovations.[79] The foundation replied to Huebner the journal his article was published in, citing Second Life and eHarmony as proof of accelerating innovation; to which Huebner replied.[80] However, Huebner’s findings were confirmed in 2010 with U.S. Patent Office data.[81] and in a 2012 paper.[82]

Innovation and development[edit]

The theme of innovation as a tool to disrupting patterns of poverty has gained momentum since the mid-2000s among major international development actors such as DFID,[83] Gates Foundation‘s use of the Grand Challenge funding model,[84] and USAID‘s Global Development Lab.[85] Networks have been established to support innovation in development, such as D-Lab at MIT.[86] Investment funds have been established to identify and catalyze innovations in developing countries, such as DFID’s Global Innovation Fund,[87] Human Development Innovation Fund,[88] and (in partnership with USAID) the Global Development Innovation Ventures.[89]

Government policies[edit]

Given the noticeable effects on efficiencyquality of life, and productive growth, innovation is a key factor in society and economy. Consequently, policymakers have long worked to develop environments that will foster innovation and its resulting positive benefits, from funding Research and Development to supporting regulatory change, funding the development of innovation clusters, and using public purchasing and standardisation to ‘pull’ innovation through.

For instance, experts are advocating that the U.S. federal government launch a National Infrastructure Foundation, a nimble, collaborative strategic intervention organization that will house innovations programs from fragmented silos under one entity, inform federal officials on innovation performance metrics, strengthen industry-university partnerships, and support innovation economic development initiatives, especially to strengthen regional clusters. Because clusters are the geographic incubators of innovative products and processes, a cluster development grant program would also be targeted for implementation. By focusing on innovating in such areas as precision manufacturinginformation technology, and clean energy, other areas of national concern would be tackled including government debtcarbon footprint, and oil dependence.[35] The U.S. Economic Development Administration understand this reality in their continued Regional Innovation Clusters initiative.[90] In addition, federal grants in R&D, a crucial driver of innovation and productive growth, should be expanded to levels similar to JapanFinlandSouth Korea, and Switzerland in order to stay globally competitive. Also, such grants should be better procured to metropolitan areas, the essential engines of the American economy.[35]

Many countries recognize the importance of research and development as well as innovation including Japan’s Ministry of Education, Culture, Sports, Science and Technology (MEXT);[91] Germany’s Federal Ministry of Education and Research;[92] and the Ministry of Science and Technology in the People’s Republic of China. Furthermore, Russia’s innovation programme is the Medvedev modernisation programme which aims at creating a diversified economy based on high technology and innovation. Also, the Government of Western Australia has established a number of innovation incentives for government departments. Landgate was the first Western Australian government agency to establish its Innovation Program.[93]

Regions have taken a more proactive role in supporting innovation. Many regional governments are setting up regional innovation agency to strengthen regional innovation capabilities.[94] In MedellinColombia, the municipality of Medellin created in 2009 Ruta N to transform the city into a knowledge city.[95]

See also[edit]


  1. ^ “Innovation” Merriam-Webster. Retrieved 14 March 2016.
  2. ^ Maranville, S. (1992). “Entrepreneurship in the Business Curriculum”. Journal of Education for Business68: 27–31. doi:10.1080/08832323.1992.10117582.
  3. ^ Franklin, Perú (2009). “Questioning two myths in innovation literature”. The Journal of High Technology Management Research20: 40–51. doi:10.1016/j.hitech.2009.02.002.
  4. ^ Bhasin, Kim (2 April 2012). “This Is The Difference Between ‘Invention’ And ‘Innovation'”Business Insider.
  5. ^ “What’s the Difference Between Invention and Innovation?”Forbes. 10 September 2015.
  6. ^ “Innovation. It’s a conveyor-belt factory processy type of thing” Retrieved 30 January 2020.
  7. ^ Growth in Services. Meeting of the OECD Council at Ministerial Level, 2005. Organisation for Economic Co-operation and Development
  8. ^ Consumer Policy Toolkit. Organisation for Economic Co-operation and Development. 2010. doi:10.1787/9789264079663-enISBN 9789264079656.
  9. ^ “EPSC – European Commission” (PDF).
  10. ^ Mazzaferro, Alexander (2018). “”Such a Murmur”: Innovation, Rebellion, and Sovereignty in William Strachey’s “True Reportory””. Early American Literature53 (1): 3–32. doi:10.1353/eal.2018.0001.
  11. ^ Mazzaferro, Alexander McLean (2017). “No newe enterprize” (Doctoral dissertation). Camden, New Jersey: Rutgers University. Retrieved 19 February 2019.
  12. ^ Lepore, Jill (23 June 2014). “The Disruption Machine What the gospel of innovation gets wrong”The New Yorker. Retrieved 19 February 2019.
  13. ^ Green, Emma (20 June 2013). “Innovation: The History of a Buzzword”The Atlantic. Retrieved 19 February 2019.
  14. Jump up to:a b Edison, H., Ali, N.B., & Torkar, R. (2014). Towards innovation measurement in the software industryJournal of Systems and Software 86(5), 1390–407.
  15. ^ Innovation in American Government: Challenges, Opportunities, and Dilemmas. Brookings Inst Pr. 1 June 1997. ISBN 9780815703587.
  16. ^ Hughes, D. J.; Lee, A.; Tian, A. W.; Newman, A.; Legood, A. (2018). “Leadership, creativity, and innovation: A critical review and practical recommendations” (PDF). The Leadership Quarterly29 (5): 549–569. doi:10.1016/j.leaqua.2018.03.001hdl:10871/32289.
  17. ^ Schumpeter, J. A. (1943). Capitalism, Socialism, and Democracy(6 ed.). Routledge. pp. 81–84. ISBN 978-0-415-10762-4.
  18. ^ Heyne, P., Boettke, P. J., and Prychitko, D. L. (2010). The Economic Way of Thinking. Prentice Hall, 12th ed. pp. 163, 317–18.
  19. ^ “Silicon Valley History & Future” Retrieved 14 March 2016.
  20. ^ Rubin, Tzameret H.; Aas, Tor Helge; Stead, Andrew (1 July 2015). “Knowledge flow in Technological Business Incubators: Evidence from Australia and Israel”. Technovation. 41–42: 11–24. doi:10.1016/j.technovation.2015.03.002.
  21. ^ Salge, Torsten Oliver; Vera, Antonio (2012). “Benefiting from Public Sector Innovation: The Moderating Role of Customer and Learning Orientation”. Public Administration Review72 (4): 550–559. doi:10.1111/j.1540-6210.2012.02529.x.
  22. ^ West, Michael A. (2002). “Sparkling Fountains or Stagnant Ponds: An Integrative Model of Creativity and Innovation Implementation in Work Groups”. Applied Psychology51 (3): 355–387. doi:10.1111/1464-0597.00951.
  23. Jump up to:a b “The Discipline of Innovation”Harvard Business Review. August 2002. Retrieved 13 October 2013.
  24. ^ Christensen, Clayton & Overdorf, Michael (2000). “Meeting the Challenge of Disruptive Change”Harvard Business Review.
  25. ^ MIT Sloan Management Review Spring 2002. “How to identify and build New Businesses”
  26. ^ Anthony, Scott D.; Johnson, Mark W.; Sinfield, Joseph V.; Altman, Elizabeth J. (2008). Innovator’s Guide to Growth. “Putting Disruptive Innovation to Work”. Harvard Business School Press. ISBN 978-1-59139-846-2.
  27. Jump up to:a b c Iansiti, Marco; Lakhani, Karim R. (January 2017). “The Truth About Blockchain”Harvard Business ReviewHarvard University. Retrieved 17 January 2017. a foundational technology: It has the potential to create new foundations for our economic and social systems.
  28. ^ Salge, T. O.; Vera, A. (2009). “Hospital innovativeness and organizational performance: Evidence from English public acute care”. Health Care Management Review34 (1): 54–67. doi:10.1097/01.HMR.0000342978.84307.80PMID 19104264.
  29. ^ Perez, T. and Rushing R. (2007). “The CitiStat Model: How Data-Driven Government Can Increase Efficiency and Effectiveness”Center for American Progress Report. pp. 1–18.
  30. ^ Transportation Research Board (2007). “Transit Cooperative Research Program (TCRP) Synthesis 70: Mobile Data Terminals”. pp. 1–5. TCRP (PDF).
  31. ^ H. Rubin, Tzameret (2015). “The Achilles heel of a strong private knowledge sector: evidence from Israel” (PDF). The Journal of Innovation Impact7 (1): 80–99.
  32. ^ Von Hippel, Eric (1988). The Sources of Innovation (PDF). Oxford University Press. Archived from the original (PDF) on 12 October 2006. Retrieved 3 December 2015.
  33. ^ Engelberger, J. F. (1982). “Robotics in practice: Future capabilities”. Electronic Servicing & Technology magazine.
  34. ^ Kline (1985). Research, Invention, Innovation and Production: Models and Reality, Report INN-1, March 1985, Mechanical Engineering Department, Stanford University.
  35. Jump up to:a b c Mark, M., Katz, B., Rahman, S., and Warren, D. (2008) MetroPolicy: Shaping A New Federal Partnership for a Metropolitan Nation. Brookings Institution: Metropolitan Policy Program Report. pp. 4–103.
  36. ^ Dubickis, M., Gaile-Sarkane, E. (2015). “Perspectives on Innovation and Technology Transfer”Procedia – Social and Behavioral Sciences213: 965–970. doi:10.1016/j.sbspro.2015.11.512.
  37. ^ “New Trends in Innovation Management” Forbes India Magazine. Retrieved 14 March 2016.
  38. ^ “ShipIt Days”. Atlassian. Retrieved 14 March 2016.
  39. ^ “U-STIR”. Archived from the original on 18 September 2011. Retrieved 7 September 2011.
  40. ^ Tuomi, I. (2002). Networks of Innovation. Oxford University Press. Networks of Innovation Archived 5 November 2007 at the Wayback Machine
  41. ^ Siltala, R. (2010). Innovativity and cooperative learning in business life and teaching. PhD thesis. University of Turku.
  42. ^ Forget The 10,000-Hour Rule; Edison, Bezos, & Zuckerberg Follow The 10,000-Experiment Rule. (2017-10-26). Retrieved on 2018-10-16.
  43. Jump up to:a b Why These Tech Companies Keep Running Thousands Of Failed Experiments. (2016-09-21). Retrieved on 2018-10-16.
  44. ^ Simulation Advantage. (2010-08-04). Retrieved on 2018-10-16.
  45. Jump up to:a b Davila, T., Epstein, M. J., and Shelton, R. (2006). “Making Innovation Work: How to Manage It, Measure It, and Profit from It.” Upper Saddle River: Wharton School Publishing.
  46. ^ Khan, Arshad M.; Manopichetwattana, V. (1989). “Innovative and Noninnovative Small Firms: Types and Characteristics”. Management Science35 (5): 597–606. doi:10.1287/mnsc.35.5.597.
  47. ^ O’Sullivan, David (2002). “Framework for Managing Development in the Networked Organisations”. Journal of Computers in Industry47 (1): 77–88. doi:10.1016/S0166-3615(01)00135-X.
  48. ^ Tarde, G. (1903). The laws of imitation (E. Clews Parsons, Trans.). New York: H. Holt & Co.
  49. ^ Rogers, E. M. (1962). Diffusion of Innovation. New York, NY: Free Press.
  50. ^ The Oxford handbook of innovation. Fagerberg, Jan., Mowery, David C., Nelson, Richard R. Oxford: Oxford University Press. 2005. ISBN 9780199264551OCLC 56655392.
  51. Jump up to:a b Edison, H.; Ali, N.B.; Torkar, R. (2013). “Towards innovation measurement in the software industry” (PDF). Journal of Systems and Software86 (5): 1390–1407. doi:10.1016/j.jss.2013.01.013.
  52. ^ Davila, Tony; Marc J. Epstein and Robert Shelton (2006). Making Innovation Work: How to Manage It, Measure It, and Profit from It. Upper Saddle River: Wharton School Publishing
  53. ^ OECD The Measurement of Scientific and Technological Activities. Proposed Guidelines for Collecting and Interpreting Technological Innovation Data. Oslo Manual. 2nd edition, DSTI, OECD / European Commission Eurostat, Paris 31 December 1995.
  54. ^ “Industrial innovation – Enterprise and Industry”. Archived from the original on 27 August 2011. Retrieved 7 September 2011.
  55. ^ Chalkidou, K.; Tunis, S.; Lopert, R.; Rochaix, L.; Sawicki, P. T.; Nasser, M.; Xerri, B. (2009). “Comparative effectiveness research and evidence-based health policy: Experience from four countries”The Milbank Quarterly87 (2): 339–67. doi:10.1111/j.1468-0009.2009.00560.xPMC 2881450PMID 19523121.
  56. ^ Roughead, E.; Lopert, R.; Sansom, L. (2007). “Prices for innovative pharmaceutical products that provide health gain: a comparison between Australia and the United States Value”. Health10 (6): 514–20. doi:10.1111/j.1524-4733.2007.00206.xPMID 17970935.
  57. ^ Hughes, B. (2008). “Payers Growing Influence on R&D Decision Making”. Nature Reviews Drug Discovery7 (11): 876–78. doi:10.1038/nrd2749PMID 18974741.
  58. ^ Faunce, T.; Bai, J.; Nguyen, D. (2010). “Impact of the Australia-US Free Trade Agreement on Australian medicines regulation and prices”. Journal of Generic Medicines7 (1): 18–29. doi:10.1057/jgm.2009.40.
  59. ^ Faunce TA (2006). “Global intellectual property protection of ‘innovative’ pharmaceuticals: Challenges for bioethics and health law in B Bennett and G Tomossy” (PDF). Globalization and Health Springer. Archived from the original(PDF) on 14 April 2011. Retrieved 18 June 2009.
  60. ^ Faunce, T. A. (2007). “Reference pricing for pharmaceuticals: is the Australia-United States Free Trade Agreement affecting Australia’s Pharmaceutical Benefits Scheme?”. Medical Journal of Australia187 (4): 240–42. doi:10.5694/j.1326-5377.2007.tb01209.xPMID 17564579.
  61. ^ Hernán Jaramillo, Gustavo Lugones, Mónica Salazar (March 2001). “Bogota Manual. Standardisation of Indicators of Technological Innovation in Latin American and Caribbean Countries”. Iberoamerican Network of Science and Technology Indicators (RICYT) Organisation of American States (OAS) / CYTED PROGRAM COLCIENCIAS/OCYT. p. 87.
  62. ^ “The INSEAD Global Innovation Index (GII)”INSEAD. 28 October 2013.
  63. ^ “Home page”Innovation Capacity Index.
  64. ^ “Tools”. Retrieved 7 September 2011.
  65. ^ Innovations Indikator retrieved 7 March 2017
  66. ^ “The INSEAD Innovation Efficiency Inndex”Technology Review. February 2016.
  67. ^ Kerle, Ralph (2013). Model for Managing Intangibility of Organizational Creativity: Management Innovation IndexEncyclopedia of Creativity, Invention, Innovation and Entrepreneurship. pp. 1300–1307. doi:10.1007/978-1-4614-3858-8_35ISBN 978-1-4614-3857-1.
  68. ^ “Innovation Index”
  69. ^ “Home page”
  70. ^ “The World Competitiveness Scoreboard 2014” (PDF). 2014.
  71. ^ “These Are the World’s Most Innovative Economies” Retrieved 25 November 2016.
  72. ^ “Infografik: Schweiz bleibt globaler Innovationsführer”Statista Infografiken. Statista (In German). Retrieved 25 November 2016.
  73. ^ “kex Data Findings Bloomberg Innovation Index” published by datawrapper, reviewd 10. September 2019
  74. ^ “Global Innovation Index Report 2019” Published by GII, reviewd 10. September 2019
  75. ^ “Innovation Indicator 2018,PDF 2,7 MB” Published by the BDI and ZEW, reviewd 10. September 2019
  76. Jump up to:a b Huebner, J. (2005). “A possible declining trend for worldwide innovation”Technological Forecasting and Social Change72(8): 980–986. doi:10.1016/j.techfore.2005.01.003.
  77. ^ Hayden, Thomas (7 July 2005). “Science: Wanna be an inventor? Don’t bother”U.S. News & World Report. Archived from the original on 1 November 2013. Retrieved 10 June 2013.
  78. ^ Adler, Robert (2 July 2005). “Entering a dark age of innovation”New Scientist. Retrieved 30 May 2013.
  79. ^ Smart, J. (2005). “Discussion of Huebner article”. Technological Forecasting and Social Change72 (8): 988–995. doi:10.1016/j.techfore.2005.07.001.
  80. ^ Huebner, Jonathan (2005). “Response by the Authors”. Technological Forecasting and Social Change72 (8): 995–1000. doi:10.1016/j.techfore.2005.05.008.
  81. ^ Strumsky, D.; Lobo, J.; Tainter, J. A. (2010). “Complexity and the productivity of innovation”. Systems Research and Behavioral Science27 (5): 496. doi:10.1002/sres.1057.
  82. ^ Gordon, Robert J. (2012). “Is U.S. Economic Growth Over? Faltering Innovation Confronts the Six Headwinds”. NBER Working Paper No. 18315doi:10.3386/w18315.
  83. ^ “Jonathan Wong, Head of DFID’s Innovation Hub | DFID bloggers” 24 September 2014. Retrieved 14 March 2016.
  84. ^ “Bill & Melinda Gates Foundation and Grand Challenge Partners Commit to Innovation with New Investments in Breakthrough Science – Bill & Melinda Gates Foundation” 7 October 2014. Retrieved 14 March 2016.
  85. ^ “Global Development Lab | U.S. Agency for International Development” 5 August 2015. Retrieved 14 March2016.
  86. ^ “International Development Innovation Network (IDIN) | D-Lab” Retrieved 14 March 2016.
  87. ^ “Global Innovation Fund International development funding”GOV.UK. Retrieved 14 March 2016.
  88. ^ “Human Development Innovation Fund (HDIF)” 14 August 2015. Retrieved 14 March 2016.
  89. ^ “USAID and DFID Announce Global Development Innovation Ventures to Invest in Breakthrough Solutions to World Poverty | U.S. Agency for International Development” 6 June 2013. Archived from the original on 4 May 2017. Retrieved 14 March 2016.
  90. ^ “U.S. Economic Development Administration : Fiscal Year 2010 Annual Report” (PDF). Retrieved 14 March 2016.
  91. ^ “Science and Technology”. MEXT. Archived from the originalon 5 September 2011. Retrieved 7 September 2011.
  92. ^ “BMBF ” Ministry”. Retrieved 7 September 2011.
  93. ^ “Home” Landgate Innovation Program. Retrieved 14 March 2016.
  94. ^ Morisson, A. & Doussineau, M. (2019). Regional innovation governance and place-based policies: design, implementation and implications. Regional Studies, Regional Science,6(1),101–116.
  95. ^ Morisson, Arnault (2018). “Knowledge Gatekeepers and Path Development on the Knowledge Periphery: The Case of Ruta N in Medellin, Colombia”. Area Development and Policy4: 98–115. doi:10.1080/23792949.2018.1538702.
showvteInventions and discoveries
showvteScience and technology studies
showvteAspects of capitalism (academic views)
Authority control GND4027089-0NDL00562508


Navigation menu




In other projects



Edit links


Bill Gates warned in 2018 that new disease could kill 30M people in 6 months

DAILY SABAHISTANBULPublished25.01.202023:46Updated26.01.202000:11

Bill Gates, Co-Chair of Bill & Melinda Gates Foundation, attends a conversation at the 2019 New Economy Forum in Beijing, China Nov. 21, 2019. Reuters File Photo

Bill Gates, Co-Chair of Bill & Melinda Gates Foundation, attends a conversation at the 2019 New Economy Forum in Beijing, China Nov. 21, 2019. (Reuters File Photo)Related Articles

Microsoft founder Bill Gates predicted in 2018 that a new disease could kill 30 million people in six months, while his foundation posted a simulation showing an epidemic spreading from China, which is currently facing a “grave situation” to handle the accelerating speed of the deadly coronavirus.

In a December 2018 report, the Business Insider cited Gates as saying that the world is not prepared for pandemics amid an increase in the population and environmental degradation.

He claimed that a small non-state actor even had the ability to build a deadlier form of smallpox in a lab environment.

Touching upon the fact that people have the ability to travel across the globe in a matter of hours in our day, Gates said that a new outbreak like SARS could kill some 30 million people in six months.

“In the case of biological threats, that sense of urgency is lacking,” Gates said, adding that countries need to prepare for pandemics in the same serious way they prepare for war.

Chinese President Xi Jinping held a politburo meeting on Saturday to discuss means to fight the coronavirus outbreak, which he said is accelerating its spread and the country is facing a “grave situation.”

The central Chinese city of Wuhan, where 41 people were reported dead, remains under lockdown to prevent the spread of the disease.Share on FacebookShare on Twitter

Previous in HealthMarie Antoinette’s hair turned white overnight, according to …Next in HealthScreening fathers for postpartum depression is as important as …DAILY SABAH RECOMMENDS

HomepageTurkeyIstanbulAnkaraEducationInvestigationsMinoritiesExpat CornerPoliticsDiplomacyLegislationWar On TerrorEU AffairsElectionsWorldMid-EastBalkansEuropeAmericasAsia PacificAfricaSyrian CrisisİslamophobiaBusinessReal EstateAutomotiveEconomyEnergyFinanceTourismTechDefenseIllustrationGalleryRSSJobsSportsFootballBasketballMotorsportsTennisLifeFeatureHealthEnvironmentTravelFoodFashionScienceReligionHistoryArtsCinemaMusicEventsBooksPortraitOpinionColumnsOp-EdReader’s CornerEditorial



Here’s what coronavirus does to the body

From blood storms to honeycomb lungs, here’s an organ-by-organ look at how COVID-19 harms humans.



MUCH REMAINS UNKNOWN about the novel coronavirus ripping through China, but one thing is certain. The disease can cast a storm over the whole human body.

Such has been the nature of past zoonotic coronaviruses, ones that hopped from animals to humans like SARS and MERS. Unlike their common-cold-causing cousins, these emergent coronaviruses can spark a viral-induced fire throughout many of a person’s organs, and the new disease—dubbed “COVID-19” by the World Health Organization on Tuesday—is no exception when it is severe.

That helps explain why the COVID-19 epidemic has killed more than 1,500 people, surpassing the SARS death toll in a matter of weeks. While the death rate for COVID-19 appears to be a tenth of SARS, the novel coronavirus has spread faster.

Confirmed cases rose to more than 60,000 on Thursday, nearly a 50 percent jump relative to the prior day, and the tally has risen by another 7,200 since then. This leap reflects a change in the way Chinese authorities are diagnosing infections instead of a massive shift in the scope of the outbreak. Rather than wait for patients to test positive for the virus, diagnoses now include anyone whose chest scan reveals COVID-19’s distinctive pattern of pneumonia. This method will hopefully allow authorities to isolate and treat patients more quickly.

If this outbreak continues to spread, there’s no telling how harmful it could become. A leading epidemiologist at the University of Hong Kong warned this week that COVID-19 could infect 60 percent of the globe if left unchecked. On Thursday, China’s National Health Commission said more than 1,700 health care workers are ill with the new virus, and the announcement came just a day after the WHO wrapped a summit on the best protocols for hospital care and the development of therapeutics, like vaccines.

But what actually happens to your body when it is infected by the coronavirus? The new strain is so genetically similar to SARS that it has inherited the title SARS-CoV-2. So combining early research on the new outbreak with past lessons from SARS and MERS can provide an answer.

The Lungs: Ground zero

For most patients, COVID-19 begins and ends in their lungs, because like the flu, coronaviruses are respiratory diseases.

They spread typically when an infected person coughs or sneezes, spraying droplets that can transmit the virus to anyone in close contact. Coronaviruses also cause flu-like symptoms: Patients might start out with a fever and cough that progresses to pneumonia or worse. (Find out how coronavirus spreads on a plane—and the safest place to sit).

After the SARS outbreak, the World Health Organization reported that the disease typically attacked the lungs in three phases: viral replication, immune hyper-reactivity, and pulmonary destruction.

Not all patients went through all three phases—in fact only 25 percent of SARS patients suffered respiratory failure, the defining signature of severe cases. Likewise, COVID-19, according to early data, causes milder symptoms in about 82 percent of cases, while the remainder are severe or critical.

Look deeper, and the novel coronavirus appears to follow other patterns of SARS, says University of Maryland School of Medicine associate professor Matthew B. Frieman, who studies highly pathogenic coronaviruses.

Medical staff members hugging each other in an isolation ward at a hospital in Zouping in China’s easter Shandong Province.PHOTOGRAPH BY STR/AFP VIA GETTY IMAGES

In the early days of an infection, the novel coronavirus rapidly invades human lung cells. Those lung cells come in two classes: ones that make mucus and ones with hair-like batons called cilia.

Mucus, though gross when outside the body, helps protect lung tissue from pathogens and make sure your breathing organ doesn’t dry out. The cilia cells beat around the mucus, clearing out debris like pollen or viruses.

Frieman explains that SARS loved to infect and kill cilia cells, which then sloughed off and filled patients’ airways with debris and fluids, and he hypothesizes that the same is happening with the novel coronavirus. That’s because the earliest studies on COVID-19 have shown that many patients develop pneumonia in both lungs, accompanied by symptoms like shortness of breath.

That’s when phase two and the immune system kicks in. Aroused by the presence of a viral invader, our bodies step up to fight the disease by flooding the lungs with immune cells to clear away the damage and repair the lung tissue.

When working properly, this inflammatory process is tightly regulated and confined only to infected areas. But sometimes your immune system goes haywire and those cells kill anything in their way, including your healthy tissue.

“So you get more damage instead of less from the immune response,” Frieman says. Even more debris clogs up the lungs, and pneumonia worsens. (Find out how the novel coronavirus compares to flu, Ebola, and other major outbreaks).LUNGS 101The lungs replenish the body with life-giving oxygen. Learn about the anatomy of the lungs, how the organs make respiration possible, and how they are vulnerable to illnesses.

During the third phase, lung damage continues to build—which can result in respiratory failure. Even if death doesn’t occur, some patients survive with permanent lung damage. According to the WHO, SARS punched holes in the lungs, giving them “a honeycomb-like appearance”—and these lesions are present in those afflicted by novel coronavirus, too.

These holes are likely created by the immune system’s hyperactive response, which creates scars that both protect and stiffen the lungs.

When that occurs, patients often have to be put on ventilators to assist their breathing. Meanwhile, inflammation also makes the membranes between the air sacs and blood vessels more permeable, which can fill the lungs with fluid and affect their ability to oxygenate blood.

“In severe cases, you basically flood your lungs and you can’t breathe,” Frieman says. “That’s how people are dying.”

The Stomach: A shared gateway

During the SARS and MERS outbreaks, nearly a quarter of patients had diarrhea—a much more significant feature of those zoonotic coronaviruses. But Frieman says it’s still not clear whether gastrointestinal symptoms play a major part in the latest outbreak, given cases diarrhea and abdominal pain have been rare. But why does a respiratory virus bother the gut at all?

When any virus enters your body, it looks for human cells with its favorite doorways—proteins on the outside of the cells called receptors. If the virus finds a compatible receptor on a cell, it can invade.WHAT IS A VIRUS?Scientists at USAMRID, the U.S. Army Medical Research Institute of Infectious diseases, work with some of the most deadly forms of life on earth, killer viruses. Learn more.

Some viruses are picky about which door they choose, but others are a little more promiscuous. “They can very easily penetrate into all types of cells,” says Anna Suk-Fong Lok, assistant dean for clinical research at the University of Michigan Medical School and former president of the American Association for the Study of Liver Diseases.

Both SARS and MERS viruses can access the cells that line your intestines and large and small colon, and those infections appear to flourish in the gut, potentially causing the damage or the leakage of fluid that becomes diarrhea.

But Frieman says we don’t know yet if the novel coronavirus does the same. Researchers believe COVID-19 uses the same receptor as SARS, and this doorway can be found in your lungs and small intestines.

Two studies—one in the New England Journal of Medicine and one preprint in medRxiv involving 1,099 cases—have also detected the virus in stool samples, which might indicate the virus could spread via feces. But this is far from conclusive.

“Whether that kind of fecal transmission is occuring for this Wuhan virus, we don’t know at all,” Frieman says. “But it definitely looks like it’s there in the stool and it looks like people do have GI symptoms associated with this.”

Blood storm

Coronaviruses can also cause problems in other systems of the body, due to the hyperactive immune response we mentioned earlier.

2014 study showed that 92 percent of patients with MERS had at least one manifestation of the coronavirus outside of the lungs. In fact, signs of a full body blitz have been witnessed with all three of the zoonotic coronaviruses: elevated liver enzymes, lower white blood cell and platelet count, and low blood pressure. In rare cases, patients have suffered from acute kidney injury and cardiac arrest.

But this isn’t necessarily a sign that the virus itself is spreading throughout the body, says Angela Rasmussen, a virologist and associate research scientist at Columbia University Mailman School of Public Health. It might be a cytokine storm.

Basically you’re bleeding out of your blood vessels.


Cytokines are proteins used by the immune system as alarm beacons—they recruit immune cells to the site of infection. The immune cells then kill off the infected tissue in a bid to save the rest of the body.

Humans rely on our immune systems to keep their cool when facing a threat. But during a runaway coronavirus infection, when the immune system dumps cytokines into the lungs without any regulation, this culling becomes a free-for-all, Rasmussen says “Instead of shooting at a target with a gun, you’re using a missile launcher,” she says. That’s where the problem arises: Your body is not just targeting the infected cells. It is attacking healthy tissue too.

The implications extend outside the lungs. Cytokine storms create inflammation that weakens blood vessels in the lungs and causes fluid to seep through to the air sacs. “Basically you’re bleeding out of your blood vessels,” Rasmussen says. The storm spills into your circulatory system and creates systemic issues across multiple organs.

From there, things can take a sharp turn for the worse. In some of the most severe COVID-19 cases, the cytokine response—combined with a diminished capacity to pump oxygen to the rest of the body—can result in multi-organ failure. Scientists don’t know exactly why some patients experience complications outside of the lung, but it might be linked to underlying conditions like heart disease or diabetes.

“Even if the virus doesn’t get to kidneys and liver and spleen and other things, it can have clear downstream effects on all of those processes,” Frieman says. And that’s when things can get serious.TODAY’SPOPULAR STORIESSCIENCESTARSTRUCKThe first person to see the ‘Pale Blue Dot’ image still has it stashed in her closetANIMALSWorld’s largest cave fish discovered in IndiaSCIENCEA huge iceberg just broke off West Antarctica’s most endangered glacier

Liver: Collateral damage

When a zoonotic coronavirus spreads from the respiratory system, your liver is often one downstream organ that suffers. Doctors have seen indications of liver injury with SARS, MERS, and COVID-19—often mild, though more severe cases have led to severe liver damage and even liver failure. So what’s happening?

“Once a virus gets into your bloodstream, they can swim to any part of your body,” Lok says. “The liver is a very vascular organ so [a coronavirus] can very easily get into your liver.”

Your liver works pretty hard to make sure your body can function properly. Its main job is to process your blood after it leaves the stomach, filtering out the toxins and creating nutrients your body can use. It also makes the bile that helps your small intestine break down fats. Your liver also contains enzymes, which speed up chemical reactions in the body.

In a normal body, Lok explains, liver cells are constantly dying off and releasing enzymes into your bloodstream. This resourceful organ then quickly regenerates new cells and carries on with its day. Because of that regeneration process, the liver can withstand a lot of injury.

When you have abnormally high levels of enzymes in your blood, though—as has been a common characteristic of patients suffering from SARS and MERS—it’s a warning sign. It might be a mild injury that the liver will quickly bounce back from or it could be something more severe—even liver failure.

Lok says scientists don’t completely understand how these respiratory viruses behave in the liver. The virus might be directly infecting the liver, replicating and killing off the cells itself. Or those cells might be collateral damage as your body’s immune response to the virus sets off a severe inflammatory reaction in the liver.

Either way, she notes that liver failure was never the sole cause of death for SARS patients. “By the time the liver fails,” she says, “oftentimes you’ll find that the patient not only has lung problems and liver problems but they may also have kidney problems. By then it becomes a systemic infection.”

Kidney: It’s all connected

Yes, your kidneys are caught up in this mess, too. Six percent of SARS patients—and a full quarter of MERS patients—suffered acute renal injury. Studies have shown the novel coronavirus can do the same. It may be a relatively uncommon feature of the disease, but it is a fatal one. Ultimately 91.7 percent of SARS patients with acute renal impairment died, according to a 2005 study in Kidney International.

Like the liver, your kidneys act as a filter your blood. Each kidney is filled with about 800,000 of microscopic distilling units called nephrons. These nephrons have two main components: a filter to clean the blood and a little tubes that return the good stuff back to your body or send the waste down to your bladder as urine.

It’s the kidney tubules that seem to be most affected by these zoonotic coronaviruses. After the SARS outbreak, the WHO reported that the virus was found in kidney tubules, which can become inflamed.

It’s not uncommon to detect a virus in the tubules if it’s in your bloodstream, says Kar Neng Lai, a professor emeritus at the University of Hong Kong and consultant nephrologist at Hong Kong Sanatorium and Hospital. As your kidneys are continuously filtering blood, sometimes the tubular cells can trap the virus and cause a transient, or milder, injury.HOW FLU VIRUSES ATTACKSee how a flu virus attacks, mutates, and becomes contagious—perhaps resulting in an outbreak or even pandemic.

That injury could become lethal if the virus penetrates the cells and begins to replicate. But Lai—who was also a member of the first group of researchers reporting on SARS and contributed to the Kidney International study—says there was no evidence that the SARS virus was replicating in the kidney.

That finding, Lai says, suggests acute kidney injury in SARS patients might be due to a diverse set of causes, including low blood pressure, sepsis, drugs, or a metabolic disturbance. Meanwhile, the more severe cases that led to acute renal failure showed signs of—you guessed it—a cytokine storm.

Acute renal failure can also sometimes be brought on by antibiotics, multi-organ failure, or being connected to a ventilator for too long. Everything is connected.

Pregnancy and coronavirus?

It’s the great irony of the Twitter age that we know too little about the novel coronavirus as we drown in information updates about it. Medical journals have published several studies about this outbreak—some more vetted than others as researchers rush to feed the maw. Meanwhile, news outlets are reporting every development. All this information whirls around the internet where discerning fact from fiction is a notorious challenge.

“This is really unprecedented in terms of the up-to-the-minute reporting on what’s going on in these studies,” Rasmussen says. “It’s really tricky trying to sort through all of the information and figure out what’s really supported, what’s speculative, and what’s plain wrong.”

For example last week, doctors at a hospital in Wuhan reported that two infants tested positive for the novel coronavirus, one just 30 hours after birth. Naturally, this troubling headline spread across news organizations, given it raised questions of whether pregnant women can infect their unborn children in utero or whether the disease can be transmitted during birth or through breast milk.

But let’s pump the breaks. Mother-to-infant transmission wasn’t observed with SARS nor MERS despite numerous cases involving pregnant women. Plus, there are other ways a newborn could catch the coronavirus, Rasmussen says, such as by being born at hospital overrun with infected patients during a hectic emergency.

In fact, a new study published Thursday in The Lancet offers preliminary evidence that the coronavirus cannot be passed from mother to child.

In the report, researchers observed nine women in Wuhan who had COVID-19 pneumonia. Some of the women had pregnancy complications, but all cases resulted in live births without evidence of transmitting the infection. While this study doesn’t completely rule out the possibility of transmission during pregnancy, it underscores the need to exercise caution in speculating about this disease.

“There needs to be a high standard of evidence before you can say that’s happening definitively—and certainly before you start making changes to how cases are managed clinically or in terms of public policy,” Rasmussen says.

Frieman agrees. He hopes this epidemic will prompt more funding for coronavirus research like the recent pledges from the European Union and the Bill & Melinda Gates Foundation. But Frieman wants the support and interest to last even if this outbreak eventually fizzles out, unlike what happened with SARS research.

“Right after the SARS outbreak, there was a big bunch of money and then it went away,” Frieman says. “Why don’t we have these answers? Nobody funded these things.”

Editor’s Note: This article has been updated to reflect the death toll and case count as of February 15. Also, the article originally misstated Anna Suk-Fong Lok’s title. She is the assistant dean for clinical research at the University of Michigan Medical School and former president of the American Association for the Study of Liver Diseases.


MORE ON THIS TOPICChina’s ‘hardware capital’ grinds to a halt amid coronavirus fearsHow coronavirus compares to flu, Ebola, and other major outbreaksHere’s how coronavirus spreads on a plane—and the safest place to sit

READ THIS NEXTPHOTOGRAPHYHow photographers capture a world besieged by infectious diseasesWith coronavirus spreading, photographers must fight ‘subtle paranoia’ to show the disease’s devastating wake.SCIENCEIn Peru, Kidney Failure Is On The Rise. No One Knows Why.What Makes This Flu Season So BadMaybe Rats Aren’t to Blame for the Black Death



SCIENCEHere’s what coronavirus does to the bodyREADSCIENCEA plague of locusts has descended on East Africa. Climate change…READSCIENCESTARSTRUCKThe first person to see the ‘Pale Blue Dot’ image still has it stashed in…READSCIENCEThese jellyfish can sting without touching you, thanks to ‘mucus…READMAGAZINEHow science will help us find our way to the futureREADLOAD MORE


MAGAZINEDeepest Dive Under Antarctica Reveals a Shockingly Vibrant WorldREAD MORE



ANIMALSTropical snakes disappearing as fungal outbreak decimates preyREADANIMALSWorld’s largest cave fish discovered in IndiaREADANIMALSHow did this rare pink manta get its color?READANIMALSWILDLIFE WATCHIllegal trade in pangolins keeps growing as criminal networks…READANIMALSChinstrap penguin numbers may have fallen by more than half on…READLOAD MORE



HISTORYPresidents’ Day technically only celebrates one presidentREADHISTORY75 years later, the Battle of Iwo Jima still haunts this veteranREADHISTORYOutsiders don’t venture into this lush corner of India. Could that…READHISTORYSusan B. Anthony fought for women’s suffrage in the face of ridiculeREADHISTORY MAGAZINEThis audacious artist shocked 17th-century Italy with her workREADLOAD MORE


HISTORYNew ‘curses’ emerge from Tut’s history-making tomb studyREAD MORE



TRAVELGoing on a cruise? Here’s how to stay healthy onboardREADTRAVELHow Ghana became the hottest destination for African-American…READTRAVELFall in love with 10 heart-shaped places around the worldSEE PHOTOSPARTNER CONTENTJapan: Imagining the future, embracing the pastREADPARTNER CONTENTPhuket, Thailand: Cultural fusion forges connectionsREADLOAD MOREPHOTO OF THE DAY

FEBRUARY 16, 2020






Newsletter SignupUnited States


Copyright © 1996-2015 National Geographic Society|Copyright © 2015-2020 National Geographic Partners, LLC. All rights reserved


  1. Spot on with this write-up, I actually assume this website needs way more consideration. I’ll most likely be again to learn much more, thanks for that info.


  2. May I simply say what a relief to uncover somebody that really knows what they are talking about on the net. You certainly understand how to bring an issue to light and make it important. A lot more people really need to read this and understand this side of your story. I was surprised that you are not more popular since you most certainly have the gift.


  3. This is a very good tip particularly to those new to the blogosphere.
    Simple but very accurate info… Many thanks for sharing this one.
    A must read article!


  4. Aw, this ᴡas a гeally nice poѕt. Taking the time and actual effort to make a superb
    article… but what can I say… Ι put things off a whole lot and don’t seem to get nearly anything done.


  5. Throughout this awesome design of things you’ll secure an A for effort and hard work. Where exactly you actually confused everybody was first in the particulars. As it is said, details make or break the argument.. And it couldn’t be more true here. Having said that, allow me inform you what exactly did give good results. Your writing can be extremely persuasive and that is possibly why I am making the effort to opine. I do not make it a regular habit of doing that. Secondly, whilst I can easily notice a jumps in reason you come up with, I am not sure of just how you appear to unite your ideas which inturn produce your final result. For now I will, no doubt subscribe to your position however wish in the near future you connect the dots better.


  6. Oh wow did you hear about Elon Musk and Grime’s baby name? It was X Æ A-12, that’s pretty weird. From what I read though, they changed it to X Æ A xii. What the heck!? Same name I guess but without the numbers. Still weird.


  7. Paxil Esotaabsor [url=]brand cialis online[/url] FLOONSNURO Generique Propecia 1mg Hemsemboto Cialis unfokeones Nebenwirkungen Cialis 10mg


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s