RESUMEN
OBJECTIVE: The aim of the present study was to determine the effect of supplementing pasture-finished steers with corn silage on the expression level of the calpain system proteins and beef tenderization. METHODS: Thirty Braford steers grazing on summer pasture were used for the study. For 120 days fifteen animals were supplemented with corn silage at 1% of body weight per head per day (Suppl) whereas the remaining 15 steers only received pasture (Contr). Carcass and meat traits were evaluated and compared between groups. Gene expression and activities of proteases (calpain 1 and calpain 2) and inhibitor (calpastatin) were measured using real-time polymerase chain reaction and casein zymography. RESULTS: Carcass and meat traits were significantly different between feeding systems. Supplemented steers showed higher hot carcass weight (p<0.01), fat content (p = 0.02), and Warner-Bratzler shear force (p = 0.03). Furthermore, the control group showed higher protease:inhibitor ratios, at mRNA (p = 0.01) and protein levels (p<0.10). Warner-Bratzler shear force and mRNA calpains:calpastatin ratio were associated in both feeding systems (p<0.01). CONCLUSION: Based on the results obtained in the study, beef tenderness differences among finishing strategies could be modulated through differential expression of the calpain system proteins.
RESUMEN
The vestigial gene (vg) was first characterized in Drosophila and several homologues were identified in vertebrates and called vestigial like 1-4 (vgll1-4). Vgll proteins interact with the transcription factors TEF-1 and MEF-2 through a conserved region called TONDU (TDU). Vgll4s are characterized by two tandem TDU domains which differentiate them from other members of the vestigial family. In Xenopus two genes were identified as vgll4. Our bioinformatic analysis demonstrated that these two genes are paralogues and must be named differently. We designated them as vgll4 and vgll4l. In situ hybridization analysis revealed that the expression of these two genes is rather different. At gastrula stage, both were expressed in the animal pole. However, at neurula stage, vgll4 was mainly expressed in the neural plate and neural folds, while vgll4l prevailed in the neural folds and epidermis. From the advanced neurula stage onward, expression of both genes was strongly enhanced in neural tissues, anterior neural plate, migrating neural crest, optic and otic vesicles. Nevertheless, there were some differences: vgll4 presented somite expression and vgll4l was localized at the skin and notochord. Our results demonstrate that Xenopus has two orthologues of the vgll4 gene, vgll4 and vgll4l with differential expression in Xenopus embryos and they may well have different roles during development.
