Evolution and Protein Folds

MARONI, GUSTAVO maroni.fordham at MHS.UNC.EDU
Fri Jul 1 08:44:09 EST 1994


In studies of the metallothionein gene in Drosophila we have found at 
least five different duplications of Mtn in European and North American  
populations, which suggests to me that duplications are relatively common 
occurrences.  In Europe these duplications seem to be favored by 
selection because in some samples they are present in up to 50% of 
chromosomes. 
In samples from Africa, on the other hand, we never found an Mtn 
duplication (0 in 400-1,000 chromosomes), which suggests to that 
duplications are very efficiently eliminated when not under selective 
pressure (If we assume that duplications occur just as often in Africa as 
in Europe).

All this would favor the notion that, in the classical scheme,  after 
duplication, both genes must remain functional (either in the old or the 
new role) pretty much continuously.  There does not seem to be much room 
for an "idle" copy that can change any which way until it stumbles onto a 
new function.

Unless I am missing something, of course.

Gustavo Maroni




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