Rainbow trout (Oncorhynchus mykiss) possess two somatostatin mRNAs that are differentially expressed

Previously, we isolated a 624-bp cDNA encoding for a 115-amino acid prepros omatostatin containing [Tyr(7),Gly(10)]-somatostatin (SS)-14 (now designate d PPSS-II') obtained from the endocrine pancreas (Brockmann bodies) of rain bow trout. In this study we have characterized a second cDNA obtained from trout pancreas that is 600-bp in length and encodes for a 111-amino acid pr ecursor containing [Tyr(7),Gly(10)]-SS-14 (PPSS-II "). The nucleotide and a mino acid identity between the two cDNAs is 82.3 and 80.5%, respectively. B oth PPSS-II' and PPSS-II " mRNA were present in esophagus, pyloric ceca, st omach, upper and lower intestine, and pancreas, whereas only SS-II " mRNA w as present in brain. PPSS-II " mRNA was more abundant than PPSS-II' mRNA in pancreas, whereas PPSS-II' mRNA was more abundant than PPSS-II " mRNA in s tomach. Fasting increased pancreatic PPSS-II " mRNA levels but had no effec t on the levels of PPSS-II' mRNA. These results indicate the existence of t wo nonallelic pancreatic SS-II genes that are differentially expressed, bot h in terms of distribution among tissues and in terms of relative abundance within the tissues.