Junk DNA

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Junk DNA is a term that has been used, often erroneously, to describe various sequences in a genome, including non-coding regions, introns, pseudogenes, and repetitive sequences. Biologists espousing Darwinian and neo-Darwinian views predicted that "junk DNA" was functionless, while researchers open to a design-view of life predicted functionality would be found. Evidence for function is now accumulating in these "junk DNA" regions, verifying predictions of intelligent design concepts.

Contents

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Origin of the phrase

The earliest use of the term "Junk DNA" in the biological literature appears to be by Dr. Susumu Ohno in his 1972 paper titled, "So much "junk" DNA in our genome."[1] Ohno focused "mainly on the fossilized genes, called pseudo genes, that are strewn like tombstones throughout our DNA." Ohno laments that it was difficult to perceive the role repetitive DNA played, and expected much of DNA to be non-functional, due to his evolutionary presuppositions. Ohno's paper is in the collection "Evolution of Genetic Systems" (1972), part of a symposia anthology of the Brookhaven National Laboratory, Biology Department, Upton, New York.

Francis Crick[2] and Sydney Brenner[3] have also been proposed as the originators of the phrase. (However, explicit citations are not given when either of these are claimed as originators.) When challenged by someone with the argument that God would not have created us with 97 per cent of redundant or useless DNA, Brenner is said to have retorted, "I said it was 'junk' DNA, not 'trash'. Everyone knows that you throw away trash. But junk we keep in the attic until there may be some need for it."

In addition to Ohno’s paper, another interesting paper in the same 1972 Brookhaven proceedings collection is by R.J. Britten, which offers an overview of early 70's perspectives on the origin/purpose of the repetitive DNA.[4] Britten reveals that, "Whether the repeated DNA in its now widely interspersed state is simply spacer between genes or carries out an active role is the subject of intensive current investigation."

Britten offered 9 possible roles of repetitive DNA, including the possibility that it was "2. CARRIED ALONG (Parasitic or garbage)." By using the term "junk DNA", Ohno was offering terminology to summarize the CARRIED ALONG proposal for the role of repetitive DNA. While scientists were searching for functionality, specific evolutionary presuppositions resulted in expectations that large portions of DNA were residual "junk". Numerous authors picked up this “junk” terminology with similar Darwinian expectations that major portions of DNA are meaningless archaic residues. For examples, see all of the hits on PubMed for the term 'junk dna'. So, there were different proposals, and there were indeed scientists looking for functions. Specific views of evolution discouraged the search for function.

D. E. Comings further discussed "junk DNA" in 1972.[5],[6]

This suggests that there are two categories of junk DNA, (1) DNA of constitutive heterochromatin which is neither transcribed nor translated, and (2) nonheterochromatic junk DNA which is probably transcribed, but not translated. This distinction adds one more dimension to the mystery of heterochromatic DNA. Why is it singled out to be nontranscribable when being nontranslatable seems adequate for most of the junk DNA? Perhaps there is clustered junk (heterochromatic DNA) and nonclustered junk, just as there is clustered repetitious DNA (satellite DNA) and nonclustered repetitious DNA.

Evolutionary biologist T. Ryan Gregory observed:[7]

"Junk DNA" is not the only offender. Non-coding DNA has been called by many names that have had the same pejorative undertones (intentional or not) implying uselessness, if not outright wastefulness. Examples include excess DNA (Zuckerkandl 1976[8]; Doolittle and Sapienza 1980[9]), surplus or nonessential or degenerate or silent DNA (Comings 1972[10]; Gilbert 1978[11]), quiet DNA (Lefevre 1971[12]), garbage DNA (Ohno 1970[13]), non-informational or nonsense DNA (Ohno 1972b[14]), worthless DNA (Ohno 1973[15]), trivial DNA (Ohno 1974[16]), vestigial DNA (Loomis 1973[17]), redundant DNA (Vinogradov 1998[18]), supplementary DNA (Hutchinson et al. 1980[19]), secondary DNA (Hinegardner 1976[20]), and incidental DNA (Jain 1980[21]).

In 1976, Richard Dawkins published his gene-centric view of evolution in a book titled The Selfish Gene.[22] In this book, Dawkins presented a view of evolution that was divergent from most other thinkers of the time, and Dawkins' book became a common reference for papers seeking to explain repetitive DNA as parasitical, including Crick and Orgel (1980). In 1992, Pagel and Johnstone reiterated these evolutionary predictions of junk-DNA having no function. [23]

While open to the possibility of functionality in the "junk DNA", Ohno and other scientists used the expression as an apt descriptor for their expectations that much of DNA showed the genetic results of evolutionary processes that were ultimately unguided, unplanned, and unpredictable. Those with strong expectations for garbage or parasitical roles for DNA were advocates of Darwinism and neo-Darwinism. In retrospect, it can be seen that the term also served as a quantifier of scientific ignorance, which was precipitated by the frustration of not readily perceiving functional roles for non-coding DNA. It also seems the only ones pushing strongly for a parasitical role were advocates of Darwinism and neo-Darwinism, lead by their standard bearer Richard Dawkins, who as late as 1998 was still promoting the junk hypothesis[24] (see Dawkins quote below). In this way, the 'junk DNA' hypothesis was originally made on explicitly neo-Darwinian grounds, and the parasite hypothesis was perpetuated by individuals who espoused this particular evolutionary view.

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Quotes supporting the term Junk DNA

Some fringe Darwinian biologists have rejected the junk DNA view, saying that if the DNA is conserved, it may have been under selective pressure because of possible function. Other Darwinian biologists refrained from speaking on the topic, apparently waiting for the actual research to come in. The more vocal and noticed Darwinian biologists often espoused the junk DNA view, so much so that viewing non-coding DNA as detritus was embraced as the traditional view of neo-Darwinian biology.

  • "These regions have traditionally been regarded as useless accumulations of material from millions of years of evolution."
- Yam, 1995[25]
  • ". . . scientists generally accept the notion that most of this [non-coding] DNA is junk."
  • "Although the high content of "junk DNA" was initially surprising when it was discovered, our current understanding of the mechanisms of genome expansion (duplication and insertion) and the apparent lack of significant selective pressure to minimize genome size combine to make the accumulation of useless sequences in our DNA seem inevitable."
- Edward Max, 2003[26]
  • "They are the remains of nature's experiments which failed. The earth is strewn with fossil remains of extinct species; is it a wonder that our genome too is filled with the remains of extinct genes?"
- Susumu Ohno, 1972[27]
  • "Most Darwinists erroneously predicted that 98.7% of the DNA was devoid of function (“junk”), while the ID/ET theory correctly predicted some yet to be decoded function of junkDNA."
- Andras Pellionisz[28]
  • "Unlike the sequence of an exon, the exact nucleotide sequence of an intron seems to be unimportant. Thus introns have accumulated mutations rapidly during evolution, and it is often possible to alter most of an intron’s nucleotide sequence without greatly affecting gene function. This has led to the suggestion that intron sequences have no function at all and are largely genetic “junk” . . ."
- Molecular biology of the Cell textbook, 1994[29]
  • ". . . a possibility that must be seriously entertained is that much repetitive DNA serves no useful purpose whatever for its host. Rather, it is selfish or junk DNA, a molecular parasite that, over many generations, has disseminated itself throughout the genome. . ."
- Biochemistry textbook, 1995[30]
  • "The simplest way to explain the surplus DNA is to suppose that it is a parasite or at best a harmless but useless passenger, hitching a ride in the survival machines created by the other DNA."
- Christian de Duve, 1996[31]
  • "The excess DNA in our genomes is junk, and it is there because it is harmless, as well as being useless, and because the molecular processes generating extra DNA outpace those getting rid of it."
- Sydney Brenner, 1998[32]
  • "...And there’s lots more DNA that doesn’t even deserve the name pseudogene. It, too, is derived by duplication, but not duplication of functional genes. It consists of multiple copies of junk, “tandem repeats”, and other nonsense which may be useful for forensic detectives but which doesn’t seem to be used in the body itself. Once again, creationists might spend some earnest time speculating on why the Creator should bother to litter genomes with untranslated pseudogenes and junk tandem repeat DNA. ... Can we measure the information capacity of that portion of the genome which is actually used? We can at least estimate it. In the case of the human genome it is about 2% - considerably less than the proportion of my hard disc that I have ever used since I bought it."
- Richard Dawkins, 1998[33]
  • "From a design point of view, pseudogenes are indeed mistakes. So why are they there? Intelligent design cannot explain the presence of a nonfunctional pseudogene, unless it is willing to allow that the designer made serious errors, wasting millions of bases of DNA on a blueprint full of junk and scribbles. Evolution, however, can explain them easily. Pseudogenes are nothing more than chance experiments in gene duplication that have failed, and they persist in the genome as evolutionary remnants of the past history of the b-globin genes."
- Ken Miller, 1994[34],[35]

If the "junk DNA" view was not the default Darwinian position, these statements might lead one to wonder why more Darwinian biologists did not protest?

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ID Predicts Function in Agenic DNA

While Kenneth Miller, Richard Dawkins, and other espousers of neo-Darwinism were portraying non-coding DNA as "junk" and "scribbles," intelligent design theorists predicted that function would be found in agenic DNA or “Junk DNA”, in contrast to Darwinian or evolutionary expectations of “worthless DNA,” “DNA tombstones,” and “parasitical DNA.”

Michael Denton in 1986 discussed "functional" and "junk" DNA sequences, in Evolution: A Theory in Crisis[36] He found that major classes of animals appear to be equidistant, not the expected evolutionary tree pattern. i.e., he posited that "junk" DNA had function. In Nature's Destiny, Denton again summarized the two positions:[37]

"If it is true that a vast amount of DNA in higher organisms is in fact junk, then this would indeed pose a very serous challenge to the idea of directed evolution or any teleological model of evolution. Junk DNA and directed evolution are in the end incompatible concepts. Only if the junk DNA contained information specifying for future evolutionary events, when it would not in a strict sense be junk in any case, could the finding be reconciled with a teleological model of evolution. Indeed, if it were true that the genomes of higher organisms contained vast quantities of junk, then the whole argument of this book would collapse. On any teleological model of evolution, most, perhaps all, the DNA in the genomes of higher organisms should have some functions."

In 1994, pro-ID scientist and Discovery Institute fellow Forrest Mims III warned against assuming that 'junk' DNA was 'useless.'" Science refused to print Mims' letter in 1994 and again in 2003.[38]

Finally, Science reports "Hints of a Language in Junk DNA" (25 November, p. 1320). Those supposedly meaningless strands of filler DNA that molecular biologists refer to as "junk" don't necessarily appear so useless to those of us who have designed and written code for digital controllers. They have always reminded me of strings of NOP (No OPeration) instructions.. . .Perhaps the "junk DNA" puzzle would be solved more rapidly if a few more computer scientists would make the switch to molecular biology.

In 1996, Michael Behe, in Darwin's Black Box, countered Kenneth Miller's 1994 "junk and scribbles" arguments. e.g., Behe posited possible functionality of pseudogene regions:[39]

"A couple of potential uses that spring to mind as I sit here at my desk include bonding to active hemoglobin genes during DNA replication in order to stabilize the DNA; guiding DNA recombination events; and aligning protein factors relative to active genes."

In 1998, John G. West, associate director of the Discovery Institute predicted:

“an ID theorist, reckoning that an intelligent designer would not fill animals' genomes with DNA that had no use, predicted that much of the "junk" DNA in animals' genomes -- long seen as the detritus of evolutionary processes -- will someday be found to have a function.” [40]

William A. Dembski predicted in 1998: [41]

"But design is not a science stopper. Indeed, design can foster inquiry where traditional evolutionary approaches obstruct it. Consider the term "junk DNA." Implicit in this term is the view that because the genome of an organism has been cobbled together through along, undirected evolutionary process, the genome is a patchwork of which only limited portions are essential to the organism. Thus on an evolutionary view we expect a lot of useless DNA. If, on the other hand, organisms are designed, we expect DNA, as much as possible, to exhibit function. And indeed, the most recent findings suggest that designating DNA as "junk" merely cloaks our current lack of knowledge about function. For instance, in a recent issue of the Journal of Theoretical Biology, John Bodnar describes how "non-coding DNA in eukaryotic genomes encodes a language which programs organismal growth and development." Design encourages scientists to look for function where evolution discourages it."

Subsequent ID theorists repeated this ID prediction that functionality would be found in agenic or "Junk" DNA.

Roland Hirsch in 2000 observed:

"2. The complexity of the genome-proteome-phenotype relationship. Research in biochemistry and molecular biology is revealing increasing complexity in this relationship, beyond the capacity of 'natural selection' and Darwinian theory to deal with. For example, segments of DNA that are not part of any gene nevertheless appear to have critical functional roles in all living organisms; they are not 'junk DNA'."[42]

Jonathan Wells in 2004:[43]

"Since non-coding regions do not produce proteins, Darwinian biologists have been dismissing them for decades as random evolutionary noise or "junk DNA." From an ID perspective, however, it is extremely unlikely that an organism would expend its resources on preserving and transmitting so much "junk." It is much more likely that noncoding regions have functions that we simply haven't discovered yet."
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Other Predictions of Functionality

T. Ryan Gregory summarizes:[44]

In fact, quite a lengthy list of proposed functions for non-coding DNA could be compiled (for an early version, see Bostock 1971[45]). Examples include buffering against mutations (e.g., Comings 1972[46]; Patrushev and Minkevich 2006[47]) or retroviruses (e.g., Bremmerman 1987[48]) or fluctuations in intracellular solute concentrations (Vinogradov 1998[49]), serving as binding sites for regulatory molecules (Zuckerkandl 1981[50]), facilitating recombination (e.g., Comings 1972[51]; Gall 1981[52]; Comeron 2001[53]), inhibiting recombination (Zuckerkandl and Hennig 1995[54]), influencing gene expression (Britten and Davidson 1969; Georgiev 1969; Nowak 1994; Zuckerkandl and Hennig 1995; Zuckerkandl 1997), increasing evolutionary flexibility (e.g., Britten and Davidson 1969[55], 1971[56]; Jain 1980[57]; reviewed critically in Doolittle 1982), maintaining chromosome structure and behaviour (e.g., Walker et al. 1969[58]; Yunis and Yasmineh 1971[59]; Bennett 1982[60]; Zuckerkandl and Hennig 1995[61]), coordinating genome function (Shapiro and von Sternberg 2005[62]), and providing multiple copies of genes to be recruited when needed (Roels 1966[63]).

Dr. Richard Sternberg in 2002 reviewed extensive evidence of functionality of certain types of junk-DNA. He concluded that:[64]

"neo-Darwinian 'narratives' have been the primary obstacle to elucidating the effects of these enigmatic components of chromosomes.". . . "the selfish DNA narrative and allied frameworks must join the other ‘icons’ of neo-Darwinian evolutionary theory that, despite their variance with empirical evidence, nevertheless persist in the literature.”

In 2005, molecular biologist Richard Sternberg and geneticist James A. Shapiro concluded:[65]

“one day, we will think of what used to be called ‘junk DNA’ as a critical component of truly ‘expert’ cellular control regimes.”
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Researchers find functions in the Junk DNA

Given the many advances in finding functional roles for the repetitive DNA,[66] the Darwinian "junk DNA" icon is turning out to be philosophically motivated junk science.

Recent research indicates that active transposable elements (which make the largest part of the "junk") actually have a strong mutagenic power. They are preferably activated under stress (i.e. situations where rapid evolution is required). Thus, one evolutionary function of transposable elements is to provide genomic rearrangements (i.e. genomic turnover) that accelerates genome evolution and provides genomic "raw material" from which new variation can arise.

Recently, researchers have begun operating on the premise that there is functionality in agenic DNA (the 98% non-coding portion of the genome) and that it is not "Junk DNA". For example Rosetta Genomics began exploring this region. Rosetta subsequently discovered about half the microRNA genes known.

Further functionality is being discovered in "Junk DNA." e.g., in the following research:

In 2007, the ENCyclopedia Of DNA Elements (ENCODE) project, organized by the National Human Genome Research Institute of the National Institutes of Health (NHGRI, of NIH), reported on its exhaustive, four-year effort studying 1% of the human genome for a parts list of biologically functional elements. The ENCODE consortium discovered that:

  1. the majority of DNA in the human genome is transcribed into functional RNA molecules
  2. these RNA transcripts extensively overlap one another.

This broad transcription pattern challenges the "junk DNA" perspective that the vast majority of the genome has no biological function, with only a small active set of discrete genes. The consortium concluded:

'However, we have also encountered a remarkable excess of experimentally identified functional elements lacking evolutionary constraint, and these cannot be dismissed for technical reasons.
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ID Predictions verified

These and many other discoveries of functionality are confirming the predictions of ID theorists and disconfirming Darwinian expectations that 98% of the genome is non-functional based on evolutionary expectations.

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Quotes recommending not using "junk DNA"

The term “junk DNA” is slowly disappearing from research findings in the biological literature, and many occurrences of the expression appear as pejorative slurs against the concept.

  • "I don't think people take the term very seriously anymore."
- Eric Green, researcher involved with the mapping of chromosome 7 (NHGRI). 1998[70]
  • "The fact that we don't know something has a function doesn't mean that in reality it does nothing."
- Carl Schmid, Ph.D., chemist, UC Davis, 1998[71]
  • "I think this will come to be a classic story of orthodoxy derailing objective analysis of the facts, in this case for a quarter of a century. ... The failure to recognize the full implications of this--particularly the possibility that the intervening noncoding sequences may be transmitting parallel information in the form of RNA molecules may well go down as one of the biggest mistakes in the history of molecular biology."
- John S. Mattick, Director, Institute for Molecular Bioscience, Univ. Queensland, Brisbane, Australia, 2003.[72]
  • "...a certain amount of hubris was required for anyone to call any part of the genome 'junk'."
- Francis Collins (2006)[73]
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References and notes

  1. ↑ Ohno S (1972) "So much "junk" DNA in our genome." Brookhaven symposia in biology, 1972;23:366-70, In: Evolution of genetic systems, HH Smith, ed., p. 80. New York: Gordon and Breach.
  2. ↑ Ridley M (2006) "The Selfish Gene: Thirty Years On", Conference, 16 March 2006. "And in a lecture at MIT in 1972 (Francis) Crick said, What is all this DNA for? Is it junk or is it an evolutionary reserve?", Available from: The Edge.
  3. ↑ Kahn CE (2006) "junk DNA." BioInformatics Glossary. Available from: http://big.mcw.edu/display.php/239.html.
  4. ↑ Britten RJ (1972) DNA sequence interspersion and a speculation about evolution. In: Evolution of genetic systems, Smith H.H., ed., p. 80. New York: Gordon and Breach.
  5. ↑ Comings DE (1972) The structure and function of chromatin. Advances in Human Genetics 3: 237-431.
  6. ↑ http://genomicron.blogspot.com/2007/04/word-about-junk-dna.html A word about "junk DNA"] T. Ryan Gregory, Genomicron.
  7. ↑ http://genomicron.blogspot.com/2007/04/word-about-junk-dna.html A Word about "junk DNA", Genomicron April 11, 2007].
  8. ↑ Zuckerkandl E (1976) Gene control in eukaryotes and the C-value paradox: "Excess" DNA as an impediment to transcription of coding sequences. Journal of Molecular Evolution 9: 73-104.
  9. ↑ Doolittle WF and Sapienza C (1980) Selfish genes, the phenotype paradigm and genome evolution. Nature 284: 601-603.
  10. ↑ Comings DE (1972) The structure and function of chromatin. Advances in Human Genetics 3: 237-431.
  11. ↑ Gilbert W (1978) Why genes in pieces? Nature 271: 501.
  12. ↑ Lefevre G (1971) Salivary chromosome bands and the frequency of crossing over in Drosophila melanogaster. Genetics 67: 497-513.
  13. ↑ Ohno S (1970) Evolution by gene duplication. Springer-Verlag: Berlin, Germany.
  14. ↑ Ohno, S. 1970b. The enormous diversity in genome sizes of fish as a reflection of nature's extensive experiments with gene duplication. Transactions of the American Fisheries Society 1970: 120-130.{check}
  15. ↑ Ohno, S. 1973. Evolutional reason for having so much junk DNA. In Modern Aspects of Cytogenetics: Constitutive Heterochromatin in Man (ed. R.A. Pfeiffer), pp. 169-173. F.K. Schattauer Verlag, Stuttgart, Germany.
  16. ↑ Ohno, S. 1974. Chordata 1: protochordata, cyclostomata, and pisces. In Animal Cytogenetics, Vol. 4 (ed. B. John), pp. 1-92. Gebrüder Borntraeger, Berlin.
  17. ↑ Loomis, W.F. 1973. Vestigial DNA? Developmental Biology 30: F3-F4.
  18. ↑ Vinogradov, A.E. 1998. Buffering: a possible passive-homeostasis role for redundant DNA. Journal of Theoretical Biology 193: 197-199.
  19. ↑ Hutchinson, J., R.K.J. Narayan, and H. Rees. 1980. Constraints upon the composition of supplementary DNA. Chromosoma 78: 137-145.
  20. ↑ Hinegardner, R. 1976. Evolution of genome size. In Molecular Evolution (ed. F.J. Ayala), pp. 179-199. Sinauer Associates, Inc., Sunderland.
  21. ↑ Jain, H.K. 1980. Incidental DNA. Nature 288: 647-648.
  22. ↑ Dawkins, R. (1976) The Selfish Gene. Oxford University Press, Oxford.
  23. ↑ Pagel, M. and R.A. Johnstone. 1992. Variation across species in the size of the nuclear genome supports the junk-DNA explanation for the C-value paradox. Proc. R. Soc. Lond. B Biol. Sci. 249: 119–124.
  24. ↑ Richard Dawkins, "The Information Challenge." the skeptic. 18,4. Autumn 1998.
  25. ↑ Yam (1995) "Talking Trash." March 1995; Scientific American Magazine Available from: http://www.sciamdigital.com/index.cfm?fa=Products.ViewIssuePreview&ARTICLEID_CHAR=6B0CE636-151B-496E-8F7E-14B648BA709.
  26. ↑ Edward Max (1986, 2003) Plagiarized Errors and Molecular Genetics, TalkOrigins FAQ Available from: http://www.talkorigins.org/faqs/molgen/
  27. ↑ Susumu Ohno (1972) "So much 'junk' DNA in our genome," Brook Haven Symposia in Biology, Vol. 23:366-370.
  28. ↑ Andras Pellionisz (2005) "One Believer’s Junk Is Another Believer’s Treasure; Quest for Predictive Scientific Theories on the Function of 'junkDNA'." Nov. 30, 2005, PRWeb.
  29. ↑ Bruce Alberts, Dennis Bray, Julian Lewis, Martin Raff, Keith Roberts, and James D. Watson (1994) Molecular biology of the Cell, pg. 373 (3rd Ed.).
  30. ↑ Donald Voet & Judith Voet (1995) Biochemistry, pg. 1138.
  31. ↑ Christian de Duve (1996) Vital Dust: Life as a Cosmic Imperative, Basic Books, pg., 222-223.
  32. ↑ Sydney Brenner (1998) "Refuge of spandrels," Current Biology, Vol. 8(19): R669.
  33. ↑ Richard Dawkins (1998) "The Information Challenge." the skeptic. 18,4. Autumn 1998.
  34. ↑ Kenneth R. Miller (1994) Life’s Grand Design, Technology Review, February - March 1994, Volume 97 (2): 24 – 32.
  35. ↑ Ken Miller may face more embarrassing facts Uncommon Descent June 16, 2007.
  36. ↑ Michael Denton, Evolution: A Theory in Crisis, Adler & Adler ISBN: 091756152X.
  37. ↑ Micheal Denton 1998, Nature's Destiny: How the Laws of Biology Reveal Purpose in the Universe. ISBN: 0743237625, p 289.
  38. ↑ Forrest Mims III, Rejected Publications, Letters, Science, 1 Dec.1994.
  39. ↑ Michael Behe, Darwin's Black Box, 1996, (1998 Touchstone edition ISBN 0-684-82754-6 pp 225-227).
  40. ↑ Pa. Trial Will Ask Whether 'Alternatives' Can Pass as Science, Rick Weiss & David Brown, Washington Post Staff Writers September 26, 2005; pA08.
  41. ↑ Science and Design, William A. Dembski, First Things, October 1, 1998.
  42. ↑ Analytical Science at the Center of Chemistry and Beyond its Frontier, Robert Hirsch, August 21, 2000; Appendix: Some Critical Points about the Theory of Evolution Added Sept 26, 2000.
  43. ↑ Using Intelligent Design Theory to Guide Scientific Research, Jonathan Wells, Discovery Institute, May 10, 2004; PCID 3.1.2, Nov. 2004, p 2.
  44. ↑ Wednesday, April 11, 2007 A word about "junk DNA". Genomicron, April 11,2007.
  45. ↑ Bostock, C. 1971. Repetitious DNA. Advances in Cell Biology 2: 153-223.
  46. ↑ Comings, D.E. 1972. The structure and function of chromatin. Advances in Human Genetics 3: 237-431.
  47. ↑ Patrushev, L.I. and I.G. Minkevich. 2006. Eukaryotic noncoding DNA sequences provide genes with an additional protection against chemical mutagens. Russian Journal of Bioorganic Chemistry 32: 1068-1620.
  48. ↑ Bremmerman, H.J. 1987. The adaptive significance of sexuality. In The Evolution of Sex and its Consequences (ed. S.C. Stearns), pp. 135-161. Birkhauser Verlag, Basel.
  49. ↑ Vinogradov, A.E. 1998. Buffering: a possible passive-homeostasis role for redundant DNA. Journal of Theoretical Biology 193: 197-199.
  50. ↑ Zuckerkandl E (1981) “A general function of noncoding polynucleotide sequences,” Molecular Biology Reports 7:1-3, 149-58.
  51. ↑ Comings DE (1972) The structure and function of chromatin. Advances in Human Genetics 3: 237-431.
  52. ↑ Gall JG (1981) Chromosome structure and the C-value paradox. Journal of Cell Biology 91: 3s-14s.
  53. ↑ Comeron JM (2001) What controls the length of noncoding DNA? Current Opinion in Genetics & Development 11: 652-659.
  54. ↑ Zuckerkandl E and Hennig W (1995) Tracking heterochromatin. Chromosoma 104: 75-83.
  55. ↑ Britten RJ and Davidson EH (1969) Gene regulation for higher cells: a theory. Science 165: 349-357.
  56. ↑ Britten RJ and Davidson EH (1971) Repetitive and non-repetitive DNA sequences and a speculation on the origins of evolutionary novelty. Quarterly Review of Biology 46: 111-138.
  57. ↑ Jain HK (1980) Incidental DNA. Nature 288: 647-648.
  58. ↑ Walker PMB, Flamm WG, and McLaren A (1969) Highly repetitive DNA in rodents. In Handbook of Molecular Cytology (ed. A. Lima-de-Faria), pp. 52-66. North-Holland Publishing Co., Amsterdam.
  59. ↑ Yunis JJ and Yasmineh WG (1971) Heterochromatin, satellite DNA, and cell function. Science174: 1200-1209.
  60. ↑ Bennett MD (1982) Nucleotypic basis of the spatial ordering of chromosomes in eukaryotes and the implications of the order for genome evolution and phenotypic variation. In Genome Evolution (eds. G.A. Dover and R.B. Flavell), pp. 239-261. Academic Press, New York.
  61. ↑ Zuckerkandl E and Hennig W (1995) Tracking heterochromatin. Chromosoma 104: 75-83.
  62. ↑ Shapiro JA and Sternberg R (2005) Why repetitive DNA is essential to genome function. Biological Reviews 80: 227-250.
  63. ↑ Roels H (1966) "Metabolic" DNA: a cytochemical study. International Review of Cytology 19: 1-34.
  64. ↑ Sternberg R (2002) "On the Roles of Repetitive DNA Elements in the Context of a Unified Genomic– Epigenetic System," Annals of the New York Academy of Sciences, Vol. 981: 154–188, 2002.
  65. ↑ Sternberg R and Shapiro JA, “How Repeated Retroelements format genome function,” Cytogenetic and Genome Research, Vol. 110: 108–116 (2005).
  66. ↑ Gibbs WW (2003) "The unseen genome: gems among the junk." Scientific American Nov;289(5):26-33.
  67. ↑ The ENCODE Project Consortium, Nature 447, 799—816 (14 June 2007) doi:10.1038/nature05874.
  68. ↑ "Encyclopedia Of DNA: New Findings Challenge Established Views On Human Genome" Science Daily June 13, 2007.
  69. ↑ http://www.genome.org/cgi/content/full/17/6/667 Volume 17, Issue 6: June 2007, ENCODE: More genomic empowerment etc. 28 papers].
  70. ↑ Kuska B (1998) "Should Scientists Scrap the Notion of Junk DNA?" JNCI 90(14): 1032-1033 July 15 1998.
  71. ↑ Kuska B (1998) "Should Scientists Scrap the Notion of Junk DNA?" JNCI 90(14): 1032-1033 July 15 1998. (His research indicates that Alu repeats are involved in regulating human protein synthesis in response to certain cellular stresses).
  72. ↑ The Gems of "Junk" DNA, W. Wayt Gibbs, Scientific American, November, 2003.
  73. ↑ Francis Collins, 2006 The unseen genome: gems among the junk. Scientific American Nov;289(5):26-33.
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See also

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Bibliography

  • Ohno S. (1972) "So much "junk" DNA in our genome." Brookhaven symposia in biology, 1972;23:366-70, In: Evolution of genetic systems, HH Smith, ed., New York: Gordon and Breach.
  • Britten, R.J. (1972) DNA sequence interspersion and a speculation about evolution. In: Evolution of genetic systems, Smith H.H., ed., p. 80. New York: Gordon and Breach.
  • Flamm W.G. (1972) Intern. Rev.Cytol. 32,1.
  • Rushton, A.R. (1975) A genetic model for the evolution of the glycosphingolipids. Journal of molecular evolution [0022-2844] Rushton yr:1975 vol:6 iss:1 pg:15 -37.
  • Dawkins, R. (1976) The Selfish Gene. Oxford University Press, Oxford.
  • Doolittle, W.F & Sapienza, C. (1980) Selfish genes, the phenotype paradigm and genome evolution. Nature, 284, 601-603.
  • Orgel, L.E. & Crick, F.H.C. (1980) Selfish DNA: the ultimate parasite. Nature, 284, 604-607.
  • Gibbs WW. (2003) The unseen genome: gems among the junk. Scientific America Nov;289(5):26-33. Erratum in: Sci Am. 2004 Mar;290(3):14.
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External Links

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