"Epigenetic regulation of translation reveals hidden genetic variation to produce complex traits" by True, Berlin, & Lindquist (Nature v. 431, 9 Sept. '04, p. 184) is one of those interesting reports that evolutionists might point to as supporting them, but may actually be very favorable to creation science. The pro-evolution argument would be that it shows a new mechanism to produce macroevolutionary change, but it looks to me like it shows a designed ability to adapt within certain limits rather than being forced to evolve or die.
Perhaps the first thing to note is that this study used Saccharomyces cerevisiae, a common yeast derived from "brewer's yeast." Yeast, plants, and animals have some significant differences in reproduction/genetics, so I'm not sure how broadly the significance of the study can be taken.
The second, but perhaps most important, observation I would make is that it seems doubtful that the traits observed can be described as "complex." Maybe "complex trait" has some technical definition that has nothing to do with the complexity of the organism. It looks like all they observed was changes in the resistance or sensitivity to different chemicals.
Judging from past cases, neither would require an increase in complexity beyond what exists or existed in some current or previous strain of the yeast. Finally, it appears the authors are not ruling out the possibility that this mechanism of adaptation merely unlocks potential variations currently hidden in "junk DNA."
What it's all about is "A single factor, the yeast prion [PSI+]," which is "a conserved, protein-based genetic element that is formed by a change in the conformation and function of the translation termination factor." The yeast can be "cured" of this prion by growing the yeast on guanidine hydrochloride. When this is done, it "alters their survival in different growth conditions and produces a spectrum of phenotypes." Apparently the prion limits the variability of the yeast. This study was aimed at finding out just what was going on. The researchers claim to show "that all traits tested involved [PSI+]-mediated read-through of nonsense codons."
Now, all this goes a bit over my head. I know that generally, prions are misfolded proteins that cause really nasty diseases like mad cow disease. In this case, however, it sounds to me like these prions are a misfolded version of a protein that's involved with chromosomes and normally serves as a stop sign or period when a cell is translating the DNA coding.
The odd thing here is that these researchers also seem to be saying that under certain conditions, having the prion form that allows the translation process to go right on into "junk DNA" regions allows the yeast to survive under certain conditions that it can't when "cured" of the prion. This ability to survive by reading through the "nonsense codons" can then become (more or less) permanent or the natural state of a strain of the yeast.
The vital questions for the relevance to creation v evolution are 1) does the survival on one substrate or another, the loss or gain of either condition, involve an increase in complexity, or merely a switching between equal levels? 2) Does the switch involve the acquisition of truly new genetic information in a way that random mutations can't provide? and does whatever apparent novelty that might arise actually reflect a designed, pre-existing source of variation for the specific purpose of providing adaptability in this one area? The report states "A probable source of the phenotypic diversity is the expression of information in previously silent regions of the genome."
I was just reading in a more recent issue about "cassettes" or sets of genetic material apparently designed ("by nature"?) to provide specific, limited variations where adaptability was required. This may be a similar case. The evolutionists are looking for new ways to introduce variation that they hope will be a better source of the virtually unlimited change they have to believe in than random mutations. What they may be finding I expect will turn out to show the complex design of built-in systems of limited adaptability that actually explains away some apparent "evolution."
It all depends on the true significance of the findings that inspired these statements: "However, the ability to switch to the [PSI+] state enables cells to benefit from a hidden potential to adapt and survive in particular circumstances." "Or are there mechanisms that allow organisms to draw on pre-existing genetic variation?" "...we suggest that protein folding mechanisms are likely to have important and unexpected roles in translating genotypes to phenotypes and are likely to influence evolution in ways that could not have been foreseen."
A sample of the technical details for those who may understand more about such things: The substrates the yeast were grown on were YPD (apparently the standard growth culture), 3 mM paraquat, 100 mM hydroxyurea, and 10 mM caffeine.
Until Next Time,
David Bump
Philippians 3: 13 Brethren, I
count not myself to have
apprehended: but [this] one thing
[I do], forgetting those things
which are behind, and reaching
forth unto those things which are
before, 14 I press toward the
mark for the prize of the high
calling of God in Christ Jesus.
http://home.att.net/~david.bump
