Effect of the nutrient microenvironment of an ovarian follicle on gap junction activity in cumulus-oocyte complexes in post-partum cows By

2012 School of Biological Science 2 Acknowledgements I would like to acknowledge, with appreciation, everyone who has contributed to this research. Firstly I would like to thank my primary supervisor Professor Ken McNatty for making it possible for me to do this research and for his patience and understanding in the face of some dumb moments on my part. I couldn't have completed this without his guidance and support and encouragement. My secondary supervisor Dr Janet Pitman has been a source of knowledge and expertise especially on writing, without which this would have been a bigger task than it was. Her suggestions were extremely beneficial and helpful for experimental design. Her patience as I struggled with the statistics was exceptional. My colleagues Dr Joy McIntosh, who convinced me to carry on when I felt it was all too much, yes the glass was half full, and Adrian Bibby who sorted out my computer problems for me of which there were many. Thank you so much. The students in the Reproduction group for their good humour, friendship and encouragement. Thanks guys. My thanks to the staff of Assure Quality at Taylor Preston Abattoirs: without their help I would not have had any tissue to work with. Your help was very much appreciated. Lastly, I wish to thank the School of Biological Sciences for allowing me to do this study. Abstract For mammalian oocyte maturation it is important for the oocyte to communicate with the surrounding somatic cells in a bidirectional manner. In part, this is achieved through gap junction connections between cumulus cells and the oocyte. These gap junctions permit the transfer of essential metabolites, nucleotides, amino acids and ions from the cumulus cells to the oocyte in order for growth and development to occur. It is hypothesized that one reason for post-partum infertility in dairy cows is poor oocyte quality due to an inappropriate nutrient microenvironment in the developing antral follicle. In turn, this might compromise the nutrient and/or energy delivery by cumulus cells to the oocyte and thus affect oocyte quality. The objectives of this study were to: (1)-develop a reliable in vitro measure of gap junction activity for bovine cumulus–oocyte-complexes (COC) using a fluorescent (calcein) dye technique, and (2)-assess the effects of different amino acid compositions, cholesterol and fatty acid concentrations on gap junction activity in COC. The development and validation of the bovine COC gap junction assay …