Meeting Abstract

98.4  Sunday, Jan. 6  Herbivorous prickleback fishes (family Stichaediae) express multiple amylase isoforms FOTI, DM*; GERMAN, DP; Univ. of California, Irvine; Univ. of California, Irvine dfoti@uci.edu

Many herbivorous vertebrates are reliant upon soluble components of their food (e.g., starch) to meet their energetic needs. Thus, herbivorous vertebrates have elevated activities of the starch-degrading enzyme amylase in their digestive tracts. In this project, we sequenced the different amylase isoforms being expressed in prickleback fishes with different diets to better understand the underpinnings of dietary amylase activity variation. Amylase encoding sequences expressed in the pyloric caeca of pricklebacks were PCR amplified with degenerate oligonucleotides, cloned and sequenced. The nucleotide sequence at the 5’- and 3’-ends were confirmed by Rapid Amplification of cDNA Ends (RACE). The herbivorous fish Cebidichthys violaceus expresses at least two amylase isoforms (and likely three or more) that have 14 missense mutations. Two species of Xiphister (the herbivorous X. mucosus and omnivorous X. atropurpureus) express two isoforms with approximately 8 mutations among them, whereas the carnivorous Anoplarchus purpurescens appears to express a single isoform. The mutations in the C. violaceus transcripts suggest that the resultant proteins may differ in their catalytic activity. This study highlights how the elevated amylase activity in X. mucosus and C. violaceous, in light of the independent evolution of herbivory in these two species, may be explained by different genetic mechanisms underlying their digestive capabilities.