Perfil mineral e proteico do plasma seminal de coelhos

Abstract

Seminal plasma is the fluid portion of semen and its presence positively affects the survival and parameters of sperm motility in rabbits. This study aimed (i) to verify the seminal concentrations of sodium, chloride and citric acid as a function of collection month, the color and aspect of the ejaculate, and to find the frequency of ejaculations with the presence of gel fraction, color and aspect of the semen of rabbits on tropical climate, (ii) to meet monthly protein spots and their possible correlation with seminal and biochemical parameters in rabbits. 20 rabbits of New Zealand White, raised in the flat-deck, fed commercial feed were used. The samples were collected twice a week, and then evaluated for volume, color, aspect, vigor, motility and sperm concentration. After the evaluations, the samples were centrifuged to obtain seminal plasma, which was stored in eppendorfs tubes at -18 oC. A monthly seminal plasma pool of each animal was made to evaluate the concentrations of sodium, chloride, citric acid and proteins. Significant monthly variations were found (p <0.05) in the concentrations of sodium, chloride and citric acid in the seminal plasma of rabbits. All mineral constituents analyzed suffered significant influence (p <0.05) by the color of the ejaculate, and the highest concentrations were found in the white-yellowish ejaculates. Correlation studies found a high and significant association between concentrations of sodium and vigor (r = 0.80, p <0.001), and between sperm concentration and citric acid (r = -0.64, p <0.02). Most of the ejaculates of rabbits showed no gel fraction. The results also showed that the white and milky ejaculate are the most common for the species. It was also observed an average concentration of 2.73 ± 0.31 mg / dl total protein in samples of seminal plasma. From the quantification of total protein were prepared two-dimensional electrophoresis gels stained SDS-PAGE with silver nitrate, with a pH gradient between 3 – 10, mesh 15% and a concentration of 100 mg of protein per sample for each month. Gels were analyzed with the Image Master 2D Platinum 6.0. ® software. The gel containing the most spots (555 spots) was the gel of the month of May, and the gel with fewer spots (71 spots) was observed in January, but no effect of month on the amount of spots was detected. The majority of spots present in seminal plasma of rabbits have pI below 8, and these spots, about 40% have pI acid, the distribution of the spots as a function of pI was homogeneous throughout the year. The distribution of spots depending on the molecular weight widely varied between the months. Except of a few months, most of the protein had a molecular weight above 100 kDa. The number of protein spot positively and moderately correlated with total protein (r = 0.57, p <0.05) and citric acid (r = 0.59, p <0.05). In silico analysis of 1411 protein spots found compatible proteins with the Swiss-Prote database and TrEMBL (UniProtKB). It is concluded that the composition of the seminal plasma of rabbits showed a broad monthly variation and ejaculated with high concentrations of citric acid are undesirable. In addition, the protein profile of rabbits has great affinity of the proteins to acidic and high molecular weight, no influence of the months of the year on the amount of protein spots identified were found and bioinformatics analysis tool does not provide consistent results with those obtained gel electrophoresis, but it allows an estimate of the probable proteins that can be found.