Proteínas do plasma seminal e sua relação com características espermáticas e nível sérico de testosterona em touros da raça nelore

Abstract

The objective of this work was to draw the electrophoretic profile of proteins from the seminal plasma and check its relationship with the spermatic characteristics, chromatin integrity and serum level of testosterone in bulls from Nelore breed. Fifty-five bulls age ranging between 24 and 28 months; they were reared under extensive management in a farm in the Uberlandia city, Minas Gerais State, in January 2006. Blood collections were carried out by puncture of the caudal vein, from 8.20 to 10.20 AM. After collection, blood was centrifuged at 700 g for 15 min and the serum stored at -20°C until the moment of analysis of the testosterone by radioimmunoassay in solid phase. Afterwards, mensuration of the scrotal circumference and semen collection were carried out by using an electroejaculator. The proximate analyses were done with the aid of an optical microscope and the analysis of the spermatic morphology by using phase contrast microscopy. Smears were prepared from semen stained with Toluidine Blue for evalution of chromatin integrity through visual and computacional analysis in SCILAB environment. It was carried out the mensuration of the head of spermatozoa, including area, perimeter, width, length, width:length ratio, elipticity, form factor, lateral symmetry and anteroposterior symmetry. The rest of ejaculate was centrifuged at 700 g for 10 minutes and the seminal plasma stored at -20°C for accomplishment of electrophoresis in 14% SDS-PAGE. Data were analyzed by Pearson´s correlation (p<0.05). We found the presence of 26 different polypeptides, with at a minimum 14 and at the maximum 21 bands individually and at a general average 17 bands per sample. The apparent molecular weight (AMW) presented an interval of 11.2 to 124.1kDa. We have found positive or negative correlations of 12 proteins with physical and morphologic characteristics of semen and 11 proteins with morphometric characteristics and chromatin integrity, showing the potential of those proteins for acting as biochemical markers, more studies being necessary for elucidating their origins and functions in the male reproductive tract.