Expression of calpastatin isoforms in three skeletal muscles of Angus steers and their association with fiber type composition and proteolytic potential.

This study aimed to evaluate the expression of calpastatin (CAST) isoforms and their potential associations with fiber type composition (%RA), calpastatin activity (CA) and myofibril fragmentation index (MFI) in three muscles with known differences in tenderness (infraspinatus, triceps brachii and semitendinosus) of Angus steers. Expression of total CAST (CAST-T) and CAST isoforms I, II, III (2-3) and III (2-4) (including or not exon 3) was evaluated by qRT-PCR. CAST expression and CA were significantly higher and MFI was lower in semitendinosus, the muscle with the highest %RA of IIX fibers.

Two methods for genotyping a 4-base deletion in the canine gene.

A 4-bp deletion (c.230_233delATAG) of the gene, frequently found in various dog breeds, results in intolerance to certain drugs routinely used in veterinary medicine, including many chemotherapeutic agents and macrocyclic lactones. The use of rapid and reliable genetic testing is fundamental for early detection of the mutation and prevention of undesirable toxicoses.