Developmental competence of different quality bovine oocytes retrieved through ovum pick-up following in vitro maturation and fertilization

Abstract

In the present study, oocytes retrieved from cross bred Karan Fries cows by ovum pick-up technique were graded into Group 1 and Group 2, based on the morphological appearance of the individual cumulus-oocyte complexes (COCs). To analyze whether the developmental potential of the COCs bears a relation to morphological appearance, relative expression of a panel of genes associated with; (a) cumulus-oocyte interaction (Cx43, Cx37, GDF9 and BMP15), (b) fertilization ( ZP2 and ZP3), (c) embryonic development ( HSF1, ZAR1 and bFGF) and (d) apoptosis and survival ( BAX, BID and BCL-XL, MCL-1, respectively) was studied at two stages: germinal vesicle (GV) stage and after in vitro maturation. The competence was further corroborated by evaluating the embryonic progression of the presumed zygotes obtained from fertilization of the graded COCs. The gene expression profile and development rate in pooled A and B grade (Group 1) COCs and pooled C and D grade (Group 2) COCs were determined and compared according to the original grades. The results of the study demonstrated that the morphologically characterized Group 2 COCs showed significantly ( P < 0.05) lower expression for most of the genes related to cumulus-oocyte interplay, fertilization and embryonic development, both at GV stage as well as after maturation. Group 1 COCs also showed greater expression of antiapoptotic genes ( BCL-XL and MCL1) both at GV stage and after maturation, while pro-apoptotic genes ( BAX and BID) showed significantly ( P < 0.05) elevated expression in poor quality COCs at both the stages. The cleavage rate in Group 1 COCs was significantly higher than that of Group 2 (74.46 ± 7.06 v. 31.57 ± 5.32%). The development of the presumed zygotes in Group 2 oocytes proceeded up to 8-to 16-cell stages only, while in Group 1 it progressed up to morulae (35.38 ± 7.11%) and blastocyst stages (9.70 ± 3.15%), indicating their better developmental potential.

Effect of BMP15 and/or AMH during in vitro maturation of oocytes from involuntarily culled dairy cows

“…R. M. Ferreira et al () reported the lower expression of genes associated with mitochondria (NRF1, POLG, POLG2, PPARGC1A, and TFAM), apoptosis (BAX and ITM2B), and oocyte maturation (FGF16, BMP15, and GDF9) due to heat stress and peak lactation. Besides, Saini et al () reported the lower expression of gene BMP15 and GDF9 in low‐quality oocytes recovered from living donors. We also observed (data not showed) that hatched Day 7.5 blastocysts were only produced when COCs from dairy cattle were maturated with BMP15 what probably indicates an improved oocyte competence.…”

Effect of E-64 Supplementation during In Vitro Maturation on the Developmental Competence of Bovine OPU-Derived Oocytes

“…CTSB activity is significantly increased in poor morphological quality oocytes and embryos when compared to those with good quality [ 14 , 19 ]. Given that OPU-derived oocytes have a relatively poor quality with high rates of apoptosis [ 13 , 18 ], it is plausible that E-64 enhanced the developmental rate and the quality of bovine COCs by regulating the apoptotic pathway ( Figure 4 ). A limitation of this study is that we used once-weekly OPU protocol that can allow for the development of dominant follicles which might affect the quality and stimulate apoptosis in oocytes within subordinate follicles.…”

“…Apoptosis is considered one of the causes of impaired developmental competence of mammalian COCs [ 14 , 15 , 16 , 17 ]. Poor quality OPU-derived COCs have higher rates of apoptosis when compared to good quality COCs [ 18 ]. We previously demonstrated that cathepsin B (CTSB) apoptotic pathway is a marker of inferior quality COCs and inversely correlated with the developmental competence of bovine COCs and preimplantation embryos (day 2, 4, and 7 embryos) [ 15 ].…”

Cumulus cell pappalysin-1, luteinizing hormone/choriogonadotropin receptor, amphiregulin and hydroxy-delta-5-steroid dehydrogenase, 3 beta- and steroid delta-isomerase 1 mRNA levels associate with oocyte developmental competence and embryo outcomes

“…A comprehensive review of the human literature for potential CC candidate mRNA biomarkers was performed [10], and genes were selected based on their functions. In some cases, the genes selected were based on data in non-human animals [18][19][20][21][22][23][24]. Gene products associated with oocyte maturation included calmodulin 1 (CALM1), gap junction alpha-4 protein (GJA4), gremlin (GREM1), and inhibitor of growth protein 1 (ING1).…”