solinge at BIOBASE.AAU.DK (Wouter van Solinge) says:
>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?
Introns are found in both coding and non-coding regions (Hawkins,
NAR,16:9853). Thus introns interrupt information, not just coding information
(Forsdyke, FASEB.J. 8:A1395). The fact that the first exon has lost coding
information does not imply that it could not have arisen from the ancestral
gene you have sequenced.
Sincerely, Don Forsdyke