Transcriptional profiles of cumulus-oocyte complexes related to developmental competence in bovine oocytes

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Virginia Tech


During folliculogenesis, oocytes and cumulus cells undergo many morphological and physiological changes. Transcriptome data were produced from single oocytes and corresponding cumulus cells (CC) to infer the differences in the transcript abundance from fully grown versus growing phase oocytes and surrounding CC. Using cow ovaries from an abattoir, COC were collected from follicles ranging from 3 to 8 mm in diameter. Cumulus-oocyte complexes were incubated in the supravital stain brilliant cresyl blue (BCB) as a means of separating oocytes based on the growth phase. Fully developed oocytes remained stained and were categorized as BCB+, whereas oocytes in the growing phase were colorless and were categorized as BCB-. Following the classification, COC were used for in vitro embryo production. Blastocyst yield from COC classified as BCB+, BCB- and unstained controls were 20%, 14% and 16.5%, respectively (P=0.18). Transcriptome data were also produced from oocytes and cumulus cells from BCB+ and BCB- COC. Transcripts from one long non-coding gene were differentially abundant in fully grown oocytes compared to oocytes in the growing phase. Eleven protein-coding genes were differentially expressed in cumulus cells collected from COC containing growing and fully grown oocytes. The results indicate no significant variation of transcript abundance of protein-coding genes in oocytes and limited regulation of transcript abundance in cumulus cells relative to the oocyte's growth phase in mid to large antral follicles.



Blastocyst, Cumulus cells, Embryo, Gene regulation, Oocyte