Differential expression dynamics of Growth differentiation factor9 (GDF9) and Bone morphogenetic factor15 (BMP15) mRNA transcripts during in vitro maturation of buffalo (Bubalus bubalis) cumulus–oocyte complexes

Muralidharan Kathirvel,Vijayarani Kumanan,Eswari Soundian

doi:10.1186/2193-1801-2-206

Muralidharan Kathirvel, Vijayarani Kumanan + Show 1 more

Open Access

https://doi.org/10.1186/2193-1801-2-206

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Abstract

The present study has evaluated the association of growth differentiation factor9 (GDF9) and bone morphogenetic protein15 (BMP15) mRNA expression in cumulus-oocyte complexes (COCs) of buffalo ovary during in vitro maturation (IVM). GDF9 and BMP15 are expressed specifically in mammalian oocytes and also participate in cumulus-oocyte crosstalk. Quantitative real-time polymerase chain reaction (qRT-PCR) technique was applied to investigate the relative abundance (RA) of GDF9 and BMP15 mRNA transcripts throughout the IVM process. Relative mRNA expression pattern of these specific genes were assessed in oocytes and cumulus cells at 0, 6, 12 and 24 h of in vitro culture. Our results revealed that RA of GDF9 during different hours of IVM showed significant reduction between 0 h and 24 h of maturation in oocytes and BMP15 transcript increased significantly (P<0.05) between 6 h and 12 h and decreased again between 12 h and 24. In cumulus cells, GDF9 remained stable during IVM upto 12 h of maturation and decreased significantly between 12 h and 24 h of maturation. Conversely, significant reduction of BMP15 was observed between 0 h and 6 h, stayed stable upto 12 h and became undetectable at 24 h of maturation. In conclusion, these two genes were differentially expressed during the period of oocyte maturation process and notably, BMP15 expression pattern is associated specifically with the period of cumulus cell expansion.

Highlights

Growth factors synthesized from mammalian oocytes popularly known as oocyte secreted factors (OSFs) play numerous role in ovarian folliculogenesis
A growing body of evidence in recent years indicated that two famous members of Transforming growth factor-β superfamily, growth differentiation factor9 (GDF9) and bone morphogenetic protein15 (BMP15) have been involved in the control of ovulation rate in mammals (Moore et al 2004)
When preparing samples for expression analysis at different maturation stages, special attention was paid to selecting cumulus-oocyte complexes (COCs) with a uniform ooplasm and appropriate cumulus expansion to ensure an accurate status of oocytes and cumulus cells

Summary

Introduction

Growth factors synthesized from mammalian oocytes popularly known as oocyte secreted factors (OSFs) play numerous role in ovarian folliculogenesis. IVM is an essential technology under assisted reproductive technologies (ARTs), which enables oocytes to achieve maturation and acquire the competence for subsequent embryonic division leading to blastocyst formation (Lonergan et al 2003; Somfai et al 2011) This technique is valuable because they allow the production of large numbers of oocytes, and because they provide a valuable in vitro model to study the gene expression at different maturational stages of oocytes. Considering the importance of buffalo and the necessity of designing potent ART protocols for this species, the current study aimed for analysing expression pattern of two oogenesis specific genes during maturation For this purpose, we used quantitative real-time PCR (qRT-PCR) technique for mRNA expression of GDF9 and BMP15 genes. The current work will provide important leads for understanding the mRNA transcriptional level of GDF9 and BMP15 genes in oocytes during IVM in case of buffalo

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