Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2005
Publication Date: 8/1/2005
Citation: Mohamed, S., Yao, J., Rexroad III, C.E., Kenney, B., Semmens, K., Killefer, J., Nath, J. 2005. Characterization of the calpastatin gene in fish: its potential role in muscle growth and fillet quality. Comparative Biochemistry and Physiology 141: 488-97. Interpretive Summary: One approach to understanding traits which are associated with aquaculture production efficiency is to conduct investigations at the molecular level. Candidate genes for a trait can be identified due to associations between a trait and a characteristic of DNA, RNA or protein. The calpastatin gene, which inhibits enzymes that breakdown proteins in the presence of calcium, is known to affect muscle growth and meat quality in agriculture species. We identified and characterized two calpastatin RNA molecules from rainbow trout and investigated the potential use of the CAST gene to monitor fish muscle growth and texture quality. This information has aided scientists in our understating of protein catabolism in fishes at the molecular level.
Technical Abstract: Calpastatin (CAST), the specific inhibitor of the calpain proteases, plays a role in muscle growth and meat quality. In rainbow trout (RT), we identified cDNAs coding for two CAST isoforms, a long (CAST-L) and a short isoform (CAST-S), apparently derived from two different genes. Zebrafish and pufferfish CAST cDNA and genomic sequences were retrieved from GenBank and their exon/intron structures were characterized. Fish CASTs are novel in that they have fewer repetitive inhibitory domains as compared to their mammalian counterparts (one or two vs. four). The expression of CAST mRNA was measured in three RT strains with different growth rates and fillet firmness that were fed either high energy or control diets. CAST-L and S expressions were significantly lower (p<0.01) in the strain that has the slowest growth rate and the softest fillet. No corresponding change was observed in calpain mRNAs due to strain or diets. However, the increase in the CAST/calpain ratio at the mRNA level did not lead to a corresponding change in the calpain catalytic activity. Further investigation should reveal the potential use of the CAST gene to monitor the fish muscle growth and texture quality.