Gene Expression Analysis of in vivo and in vitro Matured Porcine Metaphase II Oocytes

It is well established that in vitro matured oocytes lack the same developmental competence as oocytes that are matured in normal conditions in vivo. The aim of this study was to determine which transcripts are altered within in vitro matured oocytes that may lead to a decrease in their developmental ability. In the first part of this study, the transcriptomes of in vivo matured (IVV) and in vitro matured (IVM) oocytes were analyzed using the Illumina sequencing platform. Our initial analysis show that there are 715 transcripts that are differentially represented in the IVM oocytes compared to the IVV oocytes, including genes involved in chromatin modification, mRNA processing, cell cycle progression, metabolic processes, oocyte meiosis, and apoptosis regulation. In the second part of this study, relative expression levels of 29 genes were evaluated with qPCR in 33 single IVM oocytes and 29 single IVV oocytes using the Biomark® system from Fluidigm. Of the 29 genes that were evaluated, 11 genes were significantly different between the IVM and IVV oocytes and IVM oocytes had twice the variability in relative transcript abundance as the IVV oocytes. We conclude that in vitro maturation has profound and variable effects on transcript populations of metaphase-II oocytes. We expect that this data will lead to a better understanding of how we can improve the quality of oocytes that are matured in vitro as well as provide information to help to idesntify markers that could be indicative of oocyte quality.