O Instituto de Investigação e Tecnologia da Agronomia e Meio Ambiente (IITAA) desenvolve trabalho de investigação com o objetivo de perseguir estudos em diversas áreas, como a caracterização / previsão do clima insular e os efeitos das mudanças globais em comunidades do oceano para os to... Ler mais »
Sperm of 10 different bulls (3 ejaculates per bull) was used to evaluate sperm oxidative bust activity by flow cytometry, correlating this with the results of in vitro fertilization (IVF) as well as the further embryo development to the stage of blastocyst. After thawing, the straw content was split in two identical parts. One was employed for the in vitro fertilization, while the other was used for flow cytometry to evaluate sperm oxidative burst activity by an assay using 2,7-dichlorofluorescin diacetate. Sperm viability was evaluated by contrast phase fluorescent microscopy using a solution of 4′,6-Diamidino-2-phenylindole dihydrochloride and by flow cytometry using a SYBR-14 and propidium iodide viability kit. For the IVF, cumulus oocytes complexes (n=3,250), were matured in vitro for 24 h and the embryos cultured for 9 days. Presumptive zygotes were evaluated 24 hours after fertilization and eight days after to evaluate the blastocyst production. Results of sperm viability demonstrated a strong correlation between data obtained by flow cytometry and by phase contrast microscopy (r=95%, P<0.05). As far as embryo production and the sperm metabolism oxidative burst activity are concerned, it was observed that bulls, in which the burst activity was higher, resulted in better results for in vitro fertilization and on further embryo production. The correlation between burst activity and fertilization rate and further embryo development to blastocysts was respectively 98% and 96% (P<0.001). This study allows the conclusion that there is a positive correlation between bull sperm H2O2 production and their ability to fertilize bovine oocytes as well as their development to the blastocyst stage. The sperm oxidative burst activity, measured by flow cytometry, can thus be an excellent method to predict the potential fertility of different bulls.
Quinta, 31 Dezembro, 2009