May 18, 2009 | David F. Coppedge

Junk-DNA Stock Tumbles

Those investing credibility in the concept of “junk DNA” suffered more losses this week.  Repeated hits to the paradigm that portions of non-coding DNA are useless leftovers of evolution make a recovery unlikely.
    In Science,1 researchers from Princeton and Indiana University reported a function for transposons and the genes that act on them, “previously considered selfish DNA or part of the dispensable genome.”  A small eukaryote microbe uses enzymes called transposases extensively during development.  “Through an exaggerated process of genome rearrangement, Oxytricha trifallax destroys 95% of its germline genome during development,” they said, resulting in the elimination of all transposon DNA.  What’s going on?  “We show that transposase gene expression occurs during germline-soma differentiation and that silencing of transposase by RNA interference leads to abnormal DNA rearrangement in the offspring,” they said.  “This study suggests a new important role in Oxytricha for this large portion of genomic DNA that was previously thought of as junk.
Update 05/20/2009: PhysOrg reported on this paper and said, “researchers from Princeton University and Indiana University who have been studying the genome of a pond organism have found that junk DNA may not be so junky after all.  They have discovered that DNA sequences from regions of what had been viewed as the ‘dispensable genome’ are actually performing functions that are central for the organism.”  At the end of the article, PhysOrg said, “The term ‘junk DNA’ was originally coined to refer to a region of DNA that contained no genetic information.  Scientists are beginning to find, however, that much of this so-called junk plays important roles in the regulation of gene activity.  No one yet knows how extensive that role may be.”
    Another press release from Rockefeller University upset a common idea about micro-RNAs, those ubiquitous little snippets of RNA that have been found to play many important roles in the cell.  Some of these microRNAs are highly conserved (i.e., unevolved) between distant life-forms.  The assumption has been that they play similar roles; “The na?ve assumption is that if we understand what these microRNAs do in a fish or in the frog, we can extrapolate to humans,” Ali H. Brivanlou, the head of the embryology department, said.  That assumption appears to be flawed.  They found that the counterpart in humans targets different activator proteins.
personify evolution as a bumbling yet personal inventor:

  • “When evolution has lucked into efficient solutions for life’s most fundamental problems, it adopts them as invaluable family heirlooms, passing them down as one species evolves into another.”
  • Although the microRNAs are evolutionarily conserved, their target changes across species,” said Brivanlou.  “These are genetic tools that nature has invented, much like the screwdriver, to build different things for different species.”

1.  Nowacki et al, “A Functional Role for Transposases in a Large Eukaryotic Genome,” Science, 15 May 2009: Vol. 324. no. 5929, pp. 935-938, DOI: 10.1126/science.1170023.

Replacing one myth with another is not progress.  Junk DNA is a Darwinian myth that intelligent design theory could have prevented.  Geneticists looking through their Darwin-tinted glasses have misinterpreted the genome, because they expected to find waste and disorder.  An ID geneticist would face the problem differently: we don’t understand what the microRNAs and non-coding DNA segments are doing; therefore, we will discover what they are there for.
    The Darwinists have not learned their lesson.  Instead, they are retreating into their usual Charlie & Tinker Bell fairy tale.  Tinker Bell zaps genes with her mutation wand, and Charlie, the bumbling junkyard engineer, looks for scraps to cobble together into family heirlooms.  This adds the fallacies of naive assumptions [i.e., glittering generalies] and extrapolation to their logical sins.  It takes intelligence to invent a tool and use it for multiple functions.

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Categories: Dumb Ideas

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