Hi there!
An interesting article came out recently in Nature on how a prion may
improve the "evolvability" of yeast. This may have some relevance
regarding some ID hypotheses. I'd love to hear your comments on this.
Best
Marcio
http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v407/n6803/abs/407477a0_fs.html
Nature 407, 477 - 483 (2000)
A yeast prion provides a mechanism for genetic variation and phenotypic
diversity
HEATHER L. TRUE AND SUSAN L. LINDQUIST
A major enigma in evolutionary biology is that new forms or functions
often require the concerted effects of several independent genetic
changes. It is unclear how such changes might accumulate when they are
likely to be deleterious individually and be lost by selective pressure.
The Saccharomyces cerevisiae prion [PSI+] is an epigenetic modifier of the
fidelity of translation termination, but its impact on yeast biology has
been unclear. Here we show that [PSI+] provides the means to uncover
hidden genetic variation and produce new heritable phenotypes. Moreover,
in each of the seven genetic backgrounds tested, the constellation of
phenotypes produced was unique. We propose that the epigenetic and
metastable nature of [PSI+] inheritance allows yeast cells to exploit
pre-existing genetic variation to thrive in fluctuating environments.
Further, the capacity of [PSI+] to convert previously neutral genetic
variation to a non-neutral state may facilitate the evolution of new
traits.
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