Transcriptome analysis and potential mechanisms of bovine oocytes under seasonal heat stress

Heat stress is the major factor affecting cattle fertility but molecular mechanisms of deleterious impacts of elevated temperature on oocyte are still not well known. Therefore, the aim of this study is to gain a better understanding of the underlying molecular mechanism of how heat stress affects GV-stage and MII-stage oocytes and discover hub genes to heat resistance for cow oocytes. In this study, we used the bioinformatics approach to discover the differentially expressed genes between GV-stage and MII-stage oocytes, which were collected during spring and summer. When GV-stage oocytes were compared to MII-stage oocytes collected in July (Jul DEGs group) a total of 1068 genes were found as differentially expressed as a result of heat stress. Also, <i>HSPA8, COPS5, POLR2L, PSMC6,</i> and <i>TPI1</i> were identified as the common top ranked genes for the Jul DEGs group. The highest connected hub gene for the Jul DEGs group was determined as <i>HSPA8.</i> Our results showed that different heat response mechanisms might be activated to protect oocytes from elevated temperatures in cattle. The identified genes and their associated pathways might play an important role in the response to heat stress that affects the oocytes in cattle.