It's even mysterious like survivabilities are developing
themselves in need of multiple genetic changes if individual
mutations are without success or even harmful. This week Susan
Lindquist and Heather True of University
of Chicago describe a new mechanism that may be possible
to be an
explanation for yeast, at least.
This researcher pair examined the effects of a natural
"prion" protein at yeast cultures, which had to adapt
to changed conditions. In nearly half of 150 comparisons,
growth rate of yeast was changing with the prion. The prion
influences the genetic
expression by missing "stop signals" effectively
and switching on of many genes, which were shut down before.
Because these regions are normally not exprimated, they aren't
subject of selection pressure that prevents harmful mutations
from accumulation. This allows the accumulation of an arsenal
of genetic variations for yeast, which then comes free in one
moment. Therefore, a wide spectrum of new qualities can appear
with abilities like here the ability for growing up under
changed conditions.
[Nature 28.
September 2000: pp 477-483]
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