Expression of TGFβ superfamily components and other markers of oocyte quality in oocytes selected by brilliant cresyl blue staining: Relevance to early embryonic development

Abstract

Brilliant cresyl blue (BCB) is a super vital stain that has been used to select competent oocytes in different species. The objectives of present studies were to determine mRNA abundance for select TGFβ superfamily components, SMAD2/3 and SMAD1/5 phosphorylation levels and transcript abundance for other oocyte (JY1) and cumulus cell (CTSB, CTSK, CTSS and CTSZ) markers of oocyte quality in bovine oocytes and or adjacent cumulus cells classified based on developmental potential using BCB staining. The ability of exogenous FST, JY1, or cathepsin inhibitor treatment to enhance development of embryos derived from poor quality oocytes selected based on BCB staining was also determined. Cumulus oocyte complexes (COCs) from abattoir derived ovaries were subjected to BCB staining and GV stage oocytes and cumulus cells harvested from control, BCB+ and BCB- (poor oocyte quality) groups for real time PCR or Western blot analysis. Remaining COCs underwent in vitro maturation, in vitro fertilization and embryo culture in presence or absence of above described treatments. Levels of FST, JY1, BMP15 and SMAD1, 2, 3 and 5 transcripts were higher in BCB+ oocytes whereas abundance of CTSB, CTSK, CTSS and CTSZ mRNAs was higher in cumulus cells surrounding poor quality BCB- oocytes. Western blot analysis revealed SMAD1/5 and SMAD2/3 phosphorylation were higher in BCB+ than BCB− oocytes. Embryo culture studies demonstrated that follistatin and cathepsin inhibitor treatment but not JY-1 treatment can promote developmental competence of BCB- oocytes. Results provide further understanding of molecular indices of oocyte competence.

Effect of seasonality on the quality of bovine oocytes selected by the brilliant cresyl blue method

“…In this regard, Ashry et al (2015) demonstrated that abundance of oocyte gene transcripts related to maturation and proper development (such as JY-1 and BMP15) was higher in BCB + oocytes compared with BCB − . On the other hand, BCB − COCs showed increased expression of cathepsins B, S, and Z of cumulus cells.…”

“…On the other hand, BCB − COCs showed increased expression of cathepsins B, S, and Z of cumulus cells. Thus, the authors correlated the abundance of transcripts of these genes with BCB + and BCB − oocytes to prove that the BCB method can be used to acquire more competent oocytes (Ashry et al, 2015). Moreover, the use of this colorimetric method in oocytes and zygotes increases the possibility of predicting the early embryonic development potential, since oocytes with blue cytoplasm and unstained zygotes significantly increase embryo production (Mirshamsi et al, 2013).…”

“…Furthermore, researchers have identified genes that could be used as biomarkers of oocyte quality (O'Shea et al, 2012). Markers of oocyte quality were proposed in oocytes selected by BCB, with BCB + oocytes showing different gene expression profile (Ashry et al, 2015). Several authors (Alm et al, 2005;Wu, 2007;Mirshamsi et al, 2013) have evaluated selection of oocytes via BCB.…”

Differential effects of follistatin on porcine oocyte competence and cumulus cell gene expression in vitro

“…In the present study involving IVM, follistatin significantly affected oocyte maturation and subsequent post‐parthenogenetic development, consistent with the findings of a previous report (VandeVoort et al., ). Previous studies have shown that COCs are sensitive to follistatin (Ashry et al., ; Dragovic et al., ), and some investigations have evaluated both granulosa cell follistatin protein and mRNA expression (Chong et al., ). The present study determined that the presence of exogenous follistatin in porcine COCs cultured in maturation medium markedly decreased the developmental competence of oocytes without affecting early cleavage.…”

Differential Expression of Newly Identified Long Intergenic Non‐Coding RNAs in Buffalo Oocytes Indicating Their Possible Role in Maturation and Embryonic Development

“…Whereas the BCBþ oocytes presented a blue color cytoplasm (a) the BCBÀ oocytes remained colorless (b) after the staining. Following the principle of their transcription rate differences it has been established earlier that the BCBþ oocytes are significantly more competent than the BCBÀ ones [Ashry et al, 2015]. It was seen that the expression level of BOD174N increases linearly at different hours of maturation in BCBþ oocytes whereas in BCB-oocytes, it went down drastically at 24 h. In case of BOC144U, BCBþ oocytes registered linear increase in its expression up to 24 h of maturation while in BCB-oocytes, its expression decreases after reaching a peak at 8 h of maturation.…”