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Title: RELATIONSHIP OF RESTRICTION FRAGMENT LENGTH POLYMORPHISMS (RFLPS) AT THE BOVINE CALPASTATIN LOCUS TO CALPASTATIN ACTIVITY AND MEAT TENDERNESS

Author
item LONERGAN, STEVEN - UNIV OF NE - LINCOLN
item Ernst, Catherine
item BISHOP, MICHAEL - 5438-01-30
item CALKINS, CHRIS - UNIV OF NE - LINCOLN
item Koohmaraie, Mohammad

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Inconsistency in beef tenderness at the consumer level is one of the major problems facing the beef industry. This inconsistency is due to the inability to accurately classify carcasses based on their ultimate tenderness. At present, the only time that eating quality of beef is known is when it is eaten. Thus, methods to classify beef based on tenderness need to be developed. We have documented that inconsistency in beef is caused by differences in the degree of tenderization that occurs during storage of beef at refrigerated conditions (aging). Furthermore, we have determined that a naturally occurring enzyme system (calpain) is responsible for tenderization and that the level (activity) of this enzyme system will determine the extent of tenderization. The principal regulator of this enzyme system is another naturally occurring protein called calpastatin. We have shown that the level of calpastatin is negatively associated with the extent of postmortem tenderization. We have demonstrated that there exist several forms of calpastatin gene. The objective of the present experiment was to examine the relationship between forms of calpastatin gene to see if it could be used as a predictor of beef tenderness. Results indicated that there is no relationship between different forms of calpastatin gene and meat tenderness.

Technical Abstract: Restriction fragment length polymorphisms (RFLPs) have been identified at the bovine calpastatin locus. The objective of the present study was to determine if these polymorphisms are related to variations in calpastatin activity or beef tenderness. A sample of 83 crossbred steers from sires representing 8 different breeds was examined to determine this relationship. A 2.2-kb cDNA coding for domains 2 through 4 plus a 3' untranslated region of bovine calpastatin was used as a probe for calpastatin RFLPs. Polymorphisms were found using the restriction enzymes BamHI and EcoRI. Polymorphic restriction fragments for BamHI were 9.0- and 5.0-kb, and for EcoRI were 6.0- and 4.0-kb. Allelic frequencies for BamHI restriction fragments were .53 for the 9.0-kb allele and .47 for the 5.0-kb allele. Allelic frequencies for EcoRI restriction fragments were .43 for the 6.0-kb allele and .57 for the 4.0- kb allele. No polymorphisms were identified using the restriction enzymes BglII, DraI, or PstI. EcoRI and BamHI RFLPs did not explain variation in 24 h calpastatin activity, or Warner-Bratzler shear force (WBS) at 14 d postmortem (P > .05). Therefore, these polymorphisms cannot be used to predict either calpastatin activity or tenderness of aged beef in unrelated animals. The lack of a relationship between calpastatin RFLPs and meat tenderness must be distinguished from the well documented relationship between calpastatin activity and meat tenderness. Therefore, further development of calpastatin-based methods for predicting beef tenderness should focus on variation of calpastatin activity rather than polymorphisms at the calpastatin locus.