Estudo da expressão gênica do músculo longissimus dorsi de vacas e seus efeitos na maciez da carne

Abstract

The aim of this study was to evaluate the expression of genes CAST, CASP3 and DNAJA1 in longissimus dorsi muscle of adult Nelore cows. After slaughter, the carcasses were chilled for 24 hours in refrigerating chamber. Upon chilling of the carcasses were removed steaks from muscle Longissimus dorsi for the determination of shear force, being that, in the same animal were removed steaks to be maintained in chilling during 7 and 21 days, and undergo the maturation process. According to the shear force results after 24 hours, the samples were classified into two groups (G1 - Hard and G2 - Soft). Was extracted o total RNA from each sample, being this evaluated of form qualitative and quantitative. For the synthesis of cDNA was used a aliquot of 2μg of each total RNA sample, being after used in the amplification of each of the genes studied by PCR common. Each gene was cloned into a plasmid vector, from of sequencing and confirmation of each clone, plasmids were linearized and used in the construction of standard curves. Data were evaluated in a model containing of extreme values of softness. There was statistical difference (p <0.05) in shear force between treatments only on day 0. For the effect of maturation, was significant difference (p <0.05) for two times evaluated (7 and 21 days). In absolute quantification, we observed statistical difference (p <0.05) for gene CASP3, indicating a higher expression of this gene in animals that also had higher shear force values to the 0 day. While for genes DNAJA1 and CAST there was no statistical difference (p> 0.05) between groups. It is concluded that meats with higher shear force express more the gene CASP3, on the other hand, this meat suffered a greater maturation process, confirming the hypothesis that proposes the action of caspase 3 in postmortem proteolysis process.