This is interesting, on prions (remember mad cow disease?).
THE rogue proteins behind variant CJD, the human form of mad cow disease, have revealed their benign side. Prions, it seems, lie at the heart of a newly discovered form of near-instant evolution that provides life with a third way to adapt to potentially lethal environments. Crucially, it involves neither genetic nor epigenetic changes to DNA.
The conventional view is that new traits can only evolve if DNA itself changes in some way. The classic way to do this is by mutating the genetic code itself. More recently, researchers have discovered that molecules can clamp onto DNA and prevent some parts of the sequence from being read, leading to genetic changes through a process that is known as epigenetics.
Yeast breaks the mould. In challenging conditions, it can instantly churn out hundreds of brand-new and potentially lifesaving proteins from its DNA, all without changing the genes in any way. Instead, yeast alters the way genes are read. The tiny fungi convert a special type of protein called Sup35 into a prion.
Keep reading: Prions point to a new style of evolution – life – 15 February 2012 – New Scientist.
