Is "Junk" DNA Used to Provide Genetic Memory

[fthornton at ocvaxa.cc.oberlin.edu]

In article <graulCpF73w.D11 at netcom.com>, graul at netcom.com (Rick Graul) writes:
>fiddick at lifesci.lscf.ucsb.edu (Laurence Fiddick;x2791) writes:
>
>>In <graulCoz9Hq.ILx at netcom.com> graul at netcom.com (Rick Graul) writes:
>
>>>The purpose of "junk" DNA,
>>>as I understand it, is to provide a reservoir of elements
>>>which can be used by the organism for creating new genes.
>
>>i'd be interested in any references you might have on the purpose of junk dna.
>>presumably there is some cost to carrying junk dna, and i somehow find it
>>hard to believe that natural selection can maintain it for such uncertain 
>>long term interests--so any refs on this or any other arguments for the 
>>adaptive value of junk dna would be appreciated.


   It is obvious that you do not understand the basics of how evolution
works.  It would be a good idea to find a good into bio textbook and
read it for the parts on evolution.  In fact, junk 
DNA could hang around with no problem.  Evolution doesn't have a mind
and attempt to find the 'best' solutins.  As long as the junk DNA
doesn't inhibit reproductive success, there is no strong pressure t
to get rid of it.  "Presumably ther is some cost" is a big presumption.
Even if ther is a cost, it needs to be a cost on reproduction in order
to have an effect on evolutin.  Be careful... 'natural selection' doesn't
have a mind and intentions.  It doesn't attempt to maintain anything for
'long term interests'.
>
>Here's the medline entry for the paper where I first saw this idea.
>
>Search request: F PA GOULD # AND KW JUNK DNA
>Search result:  1 citation in the Medline database
>
>Type HELP for other display options.
>
>1. Brosius J; Gould SJ.
>     On "genomenclature": a comprehensive (and respectful) taxonomy for
>     pseudogenes and other "junk DNA".
>   Proceedings of the National Academy of Sciences of the United States of
>   America, 1992 Nov 15, 89(22):10706-10.
>     (UI:  93066312)
>         (PE title:  Proceedings of the National Academy of Sciences of the
>         United States of America.)
>
>Abstract: Genomic nomenclature has not kept pace with the levels and depth of
>    analyzing and understanding genomic structure, function, and evolution. We
>    wish to propose a general terminology that might aid the integrated study
>    of evolution and molecular biology. Here we designate as a "nuon" any
>    stretch of nucleic acid sequence that may be identifiable by any criterion.
>    We show how such a general term will facilitate contemplation of the
>    structural and functional contributions of such elements to the genome in
>    its past, current, or future state. We focus in this paper on pseudogenes
>    and dispersed repetitive elements, since their current names reflect the
>    prevalent view that they constitute dispensable genomic noise (trash),
>    rather than a vast repertoire of sequences with the capacity to shape an
>    organism during evolution. This potential to contribute sequences for
>    future use is reflected in the suggested terms "potonuons" or "potogenes."
>    If such a potonuon has been coopted into a variant or novel function, an
>    evolutionary process termed "exaptation," we employ the term "xaptonuon."
>    If a potonuon remains without function (nonaptive nuon), it is a
>    "nonaptation" and we term it "naptonuon." A number of examples for
>    potonuons and xaptonuons are given.
>
>
>-- 
>Rick Graul
>graul at netcom.com