Expressão gênica em embriões de Bos taurus e Bos indicus produzidos in vivo e in vitro

Abstract

Embryos produced in vivo and in vitro show morphological and developmental differences, which can be influenced by culture environment. Nevertheless, there are few studies showing the effect of in vitro environment on embryos from different bovine breeds, such as Gyr (Bos indicus) and Holstein (Bos taurus). Some important genes associated to formation, survival and subsequent development of bovine embryos can be affected by various factors related to the production system and breed. The aim of this study was to evaluate the relative abundance of transcripts associated to water transport (Aquaporins), blastocoel formation (Na/K-ATPases), apoptosis (BAX) and response to cellular stress (Peroxiredoxin 1) in bovine blastocysts from Gyr and Holstein breed produced in vivo and in vitro to identify breed and/or production system effects. For each group (Gyr-in vivo; Gyr-in vitro; Holstein-in vivo; Holstein-in vitro), blastocysts (n=15) distributed in 3 pools were used for RNA extraction, followed by RNA amplification and reverse transcription. The cDNAs obtained were submitted to Real-Time PCR, using the H2a gene as endogenous control, and analyzed with REST software©. For the production system in the Gyr embryos, the relative expression of PRDX1 gene was down-regulated (p<0.01) as well as Na/K-ATPase-β2 and BAX genes (p<0.05), and the AQP3, AQP11 and Na/K-ATPase-α1 genes were not significantly different (p>0.05) when in vitro embryos were compared with in vivo produced ones. In Holstein embryos, BAX was up-regulated in in vitro embryos (p<0.01), while AQP3, AQP11, Na/K-ATPaseα1, Na/K-ATPase-β2 and PRDX1 genes were not significantly different (p>0.05) from in vivo produced embryos. When the breed effect was evaluated, Holstein in vivo produced blastocysts presented AQP3, Na/K-ATPase-α1, PRDX1, and BAX genes down-regulated (p<0.05) while Na/K-ATPase-β2 and AQP11 genes were not significantly different (p>0.05) from Gyr embryos. For the in vitro produced embryos, only Bax was up-regulated (p<0.05) in Holstein embryos compared with Gyr embryos. Based on those results, for the evaluated genes, it is possible to conclude that are inherent breed differences in gene expression observed in in vivo produced embryos and that the in vitro production system influences in the relative expression in both breeds, attenuating the inherent breed differences. Other genes should be evaluated for a better understanding of these breeds differences.