gene evolution and intron position

Wouter van Solinge solinge at BIOBASE.AAU.DK
Thu Oct 13 08:12:12 EST 1994


Dear Evolution-netters,

	We are currently studying the evolution of a neuropeptide family 
and have isolated the active peptide and cloned the cDNA and gene 
encoding this peptide from a protochordate.  Comparison of the active 
peptide sequence (8 amino acids in length) with peptide sequences from 
many known higher chordates unequivocally suggest that these peptides 
have a common evolutionary origin.

	The gene from the protochordate has three exons and two introns, 
as does all known examples from other species (all mammalian examples).  
However in the higher chordates the first exon is non-coding whereas in 
the protochordate gene the first exon encodes 46 amino acids.   In 
current molecular evolutionary theory could the protochordate gene be the 
ancestral gene of that found in higher chordates or does the position of 
introns indicate that they had to have arisen independantly from a yet 
uncharacterized ancestral gene?

	Any thoughts from people with a much broader knowledge of 
molecular evolutionary theory (which wouldn't be hard) would be greatly 
appreciated.


					Regards

					Wouter, Ulrik and Ian



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