Gene expression comparison between bovine oocytes matured in vivo or in vitro, and evaluation of the vitrification influence in this expression

Abstract

The adequate embryo development is directly relates to events occurred during foliculogenesis, when the oocyte acquires the capacity of developing. This capacity is directly related to the expression of many genes and accumulation of transcripts and translation machinery, which will be used during the early embryonic cleavages, when the embryonic genome is silenced. Thus, the fine temporal control of gene expression in follicle cells is essential for follicular development and subsequent maturation of germ cells. The selection of oocytes is crucial to the success of assisted reproduction techniques (ART), it have been observed that in vitro matured oocytes are less competent in their development when compared to those matured in vivo. Significant differences in expression pattern of some genes have also been described, if it allows the definition of some gene markers to predict oocytes competence in in vitro or in vivo matured oocytes, it may improve the conditions and protocols for ART and consequently pregnancy results. Cryopreservation of oocytes is a relatively new technique that have been recently used as a good method to preserve fertility in young women suffering from malignant neoplasms, who are candidates to sterility due to the effects of gonadotoxic treatment. Oocyte cryopreservation can also interfere with gene expression in oocytes of ART. In this context, the objective of this project is to analyze the expression of approximately 50 genes related to oocyte development, directly or indirectly, evaluating samples of bovine oocytes matured in vivo and in vitro. Also to evaluate the possible influence of vitrification technique (a type of cryopreservation) in the expression of the same selected genes. These data will provide information about the possible influence of the cultive and/or vitrification on gene expression of these groups of genes in bovine oocytes, an experimental model recognized for research in reproduction with similarity to human characteristics. (AU)