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
Wouter, Ulrik and Ian