Proteome Analysis of Bovine Longissimus dorsi Muscle Associated with the Marbling Score

Abstract

The breeding value of marbling score in skeletal muscle is an important factor for evaluating beef quality. In the present study, we investigated proteins associated with the breeding value of the marbling score for bovine sirloin to select potential biomarkers to improve meat quality through comparative proteomic analysis. Proteins isolated from muscle were separated by two-dimensional gel electrophoresis. After analyzing images of the stained gel, seven protein spots for the high marbling score group were identified corresponding to changes in expression that were at least two-fold compared to the low marbling score group. Four spots with increased intensities in the high marbling score group were identified as phosphoglycerate kinase 1, triosephophate isomerase, acidic ribosomal phosphoprotein PO, and capping protein (actin filament) Z-line alpha 2. Spots with decreased intensities in the high marbling score group compared to the low score group were identified as 14-3-3 epsilon, carbonic anhydrase II, and myosin light chain 1. Expression of myosin light chain 1 and carbonic anhydrase 2 was confirmed by Western blotting. Taken together, these data could help improve the economic performance of cattle and provide useful information about the underlying the function of bovine skeletal muscle.

Keywords: Cattle; Marbling Score; Proteomics; Sirloin; Skeletal Muscle.

Figure 1

2-DE images of bovine longissimus dorsi muscle. (A) Protein patterns of bovine sirloin taken from high and low marbling score (MS) groups. One hundred μg of protein extracts were separated by 2-DE and stained with a silver staining kit. Spots corresponding to differently expressed proteins are indicated by arrows. (B) The magnified fields of the 2-DE images showing differences in protein expression patterns between the high and low MS groups. (C) Quantification of differentially expressed proteins in bovine muscle. Student’s t-test was performed to compare protein expression patterns between the high and low MS groups (n = 20, * p<0.05; ** p<0.01).

Figure 2

Expression of proteins identified in bovine longissimus dorsi tissue. Proteins were extracted from three representative samples from both groups. The expression of myosin light chain 1 and carbonic anhydrase 2 was assessed by Western blot analysis. Actin was used as a loading control.