PARENT SESSION

(M475) SEARCHING A MULTI-LEVEL DEVELOPMENTAL COMPETENCE BOVINE OOCYTE GENE.

Mourot, Marina¹, Duffort, Isabelle¹, Gravel, Catherine ¹, Algryani , Omran², Dieleman , Steph ², Sirard, Marc Andre¹, ¹ Université Laval, Québec, QC, CANADA.² Utrecht University, Utrecht, The Netherlands.

ABSTRACT- Our hypothesis is that some of the determining genes related to developmental oocyte competence are accumulated in oocyte in the following favorable situations: oocytes from follicles larger than 5mm, oocytes treated with r-hFSH during in vitro maturation, oocytes obtained from stimulated animals 6 hrs post LH and oocytes (zygotes) that end up cleaving earlier than 36 hrs post fertilization cleavage two cell embryos. The same genes are likely in lower amounts in the unfavorable situations: in vitro maturation without hormone, late cleavage two cell embryos and oocytes from less than 5 mm follicles size. Our objective is to identify those genes by comparing the abundance of their transcripts. A SSH (suppressive subtractive hybridization) cDNA library was constructed with the oocytes recovered 6h post LH and oocytes matured in vitro for 6h without FSH to obtain the most and less favorable conditions. Four hundred ESTs were spotted on a glass micro array and then sequenced and identify with the algorithm BLAST. Microarrays hybridization with the different favorable and unfavorable conditions was done to select 12 candidates with potentially more abundant mRNA in vivo or in response to r-hFSH or in early cleavage. Among the potential candidates identified after hybridizations on microarrays, we encountered factors on cellular cycle regulation, cellular signalization, antioxidant protection, cyclins and transforming growth factor- superfamily. Quantitative PCR will determine which candidates are the best markers of competence. This work was supported by NSERC Canada

KEY WORDS: oocyte competence, in vitro maturation, FSH, bovine