In vivo and in vitro maturation of rabbit oocytes differently affects the gene expression profile, mitochondrial distribution, apoptosis and early embryo development

Abstract

In vivo-matured cumulus-oocyte complexes are valuable models in which to assess potential biomarkers of rabbit oocyte quality that contribute to enhanced IVM systems. In the present study we compared some gene markers of oocytes and cumulus cells (CCs) from immature, in vivo-matured and IVM oocytes. Moreover, apoptosis in CCs, nuclear maturation, mitochondrial reallocation and the developmental potential of oocytes after IVF were assessed. In relation to cumulus expansion, gene expression of gap junction protein, alpha 1, 43 kDa (Gja1) and prostaglandin-endoperoxide synthase 2 (Ptgs2) was significantly lower in CCs after in vivo maturation than IVM. In addition, there were differences in gene expression after in vivo maturation versus IVM in both oocytes and CCs for genes related to cell cycle regulation and apoptosis (V-Akt murine thymoma viral oncogene homologue 1 (Akt1), tumour protein 53 (Tp53), caspase 3, apoptosis-related cysteine protease (Casp3)), oxidative response (superoxide dismutase 2, mitochondrial (Sod2)) and metabolism (glucose-6-phosphate dehydrogenase (G6pd), glyceraldehyde-3-phosphate dehydrogenase (Gapdh)). In vivo-matured CCs had a lower apoptosis rate than IVM and immature CCs. Meiotic progression, mitochondrial migration to the periphery and developmental competence were higher for in vivo-matured than IVM oocytes. In conclusion, differences in oocyte developmental capacity after IVM or in vivo maturation are accompanied by significant changes in transcript abundance in oocytes and their surrounding CCs, meiotic rate, mitochondrial distribution and apoptotic index. Some of the genes investigated, such as Gja1, could be potential biomarkers for oocyte developmental competence in the rabbit model, helping improve in vitro culture systems in these species.

Meiotic arrest with roscovitine and follicular fluid improves cytoplasmic maturation of porcine oocytes by promoting chromatin de-condensation and gene transcription

“…Oxidative stress could influence IVM of oocytes 21 , and cytoplasmic GSH has been defined as an important index for cytoplasmic maturation of porcine oocytes 22 , 23 . Furthermore, while an optimal cumulus expansion is essential for normal oocyte maturation and embryo development, a high rate of apoptosis in cumulus cells is associated with impaired oocyte cytoplasmic maturation 24 . Human IVF embryo quality showed a negative correlation with the level of cumulus cell apoptosis 25 .…”

The Role of Glucose Metabolism on Porcine Oocyte Cytoplasmic Maturation and Its Possible Mechanisms

“…Although several researchers have reported effects of glucose metabolism on oocyte maturation, knowledge of the underlying mechanism(s) is still limited [8, 13]. Moreover, even though other studies have observed that glucose metabolism during oocyte maturation can significantly affect in vitro fertilization and subsequent post-embryonic development [11, 14–17], the effect of glucose metabolism on oocyte cytoplasm maturation has not been studied so far.…”

Transcriptome dynamics in early in vivo developing and in vitro produced porcine embryos

“…However, blastocyst quality assessed by the expression of genes related to metabolism (GLUT1 and LDHA), antioxidant response (SOD2 and GPX1), growth factors and apoptosis (IGF2R, BCL2 and BAX), methylation (DNMT3B), and blastocyst quality (AKR1B1, POU5F1 and CDX2) were not affected (21). In addition, the blastocyst rates of in vivo and in vitro matured rabbit oocytes did not signi cantly differ, while at earlier developmental stages, the in vivo embryo development rates were signi cantly higher than observed for embryos produced with in vitro matured oocytes (22). Thus, while oocyte quality and competence, and subsequent embryo development are affected by the maturation conditions, only minor transcriptional differences have been reported at the hatched blastocyst stage (23).…”