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qetzal



Posts: 309
Joined: Feb. 2006

(Permalink) Posted: Dec. 24 2011,15:52   

Quote (Southstar @ Dec. 23 2011,09:42)
Another thing did Lenski ever get round to finding the origin of the CIT+ mutation, was it epigenics or a two step indipendant mutation.

Epigenetics. It doesn't mean what you seem to think it means.

A mutation is a heritable change in the DNA base sequence. Epigenetics cannot, by definition, involve a change in the DNA sequence. Instead, it involves things like base modification (e.g. methylation) or alteration of the pattern of histones binding to DNA. So it's non-sensical to ask if the origin of the CIT+ mutation could be epigenetics. Just so you understand the terminology.

What you're really trying to ask is whether the CIT+ phenotype (i.e. the observed ability to use citrate as an energy source) is due to a mutation or due to some epigenetic change. I don't know the answer for a fact, but I can almost guarantee that it's due to mutation. E. coli does utilize things like methylation and histone-like proteins, but I'm not aware of any case in E. coli where an epigenetic change could cause the appearance of something like the CIT+ phenotype.

Note that I didn't bother to see if Lenski has identified a mutation responsible for the CIT+ phenotype. I'd guess that he has, but I'll let you hunt that down yourself.

  
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