PARENT SESSION
Oocyte Development

CYSTEINE ENHANCES IN VITRO MATURATION OF BOVINE OOCYTE AND SUBSEQUENT EMBRYO DEVELOPMENT .

Ali, Atef¹, Bilodeau, Jean-François¹, Sirard, Marc-André¹, ¹

ABSTRACT- The present study was carried out to determine the effect of cysteine, catalase and superoxide dismutase (SOD) on in vitro maturation and fertilization of bovine oocytes, and subsequent embryonic development. Bovine oocytes were matured, fertilized and cultured in defined condition in vitro with antioxidant supplementation: cysteine (0.6mM), SOD (100 or 1000U/ml) and catalase (5 or 125U/ml). Significant improvements in the proportion of oocytes undergoing morula and blastocyst development (33.3% vs 20.3%,P<0.05) were achieved when cysteine was added to the maturation medium as compared to control medium without antioxidant supplementation. In contrast, the addition of SOD or catalase at both concentrations did not improve the proportion of oocytes undergoing morula and blastocyst development. During the insemination interval, addition of cysteine, SOD or catalase (low concentrations) did not decrease nor increase the percentage of embryos produced, but increasing concentrations of these antioxidants significantly reduced the percentage of morula and blastocyst stages (P<0.05). During embryo culture (m-SOF+BSA, 88%N₂ ,7%O₂ , 5%CO₂), the addition of cysteine improved the development of bovine embryos but neither SOD nor catalase had any effect on the embryonic development. The results of this study suggest that cysteine supplementation that permeates the cells during IVM and IVC improved the rate of bovine embryo development, but antioxidants effective outside the cells did not improve the proportion of oocytes undergoing morula and blastocyst development. Acknowledgment: This work was supported by conseil de recherches en sciences naturelles et en genie du canada (CRSNG).

KEY WORDS: Bovine, Oocyte, Cysteine