Mitochondrial content and gene expression profiles in oocyte-derived embryos of cattle selected on the basis of brilliant cresyl blue staining

The aim of this study was to investigate the developmental rate, lipid and mitochondrial distribution and gene expression in oocyte-derived embryos selected on the basis of brilliant cresyl blue (BCB) staining. Lipid content and mitochondrial distribution in Day 8 blastocysts were evaluated by fluorescence intensity, while gene expression was analyzed by real-time PCR. The proportion of blastocysts (30.9%) was greater (P<0.05) in BCB+ than in BCB- oocytes (13%) but not different (P>0.05) from the control group (28.2%). Total cell number was also greater in BCB+ (155.1 ± 36.2) than in BCB- (116.6 ± 40.5) and control (127.5 ± 35.7) blastocysts. Furthermore, the apoptotic cell number was less in BCB+ (3.7 ± 4.4) than in BCB- blastocysts (8.7 ± 8.7) but not different from the control group (5.9 ± 3.9). BCB+ embryos contained more mitochondria compared to BCB- embryos (P<0.05). There was no significant difference in intercellular lipid accumulation in embryos from all groups. Interferon-τ (IFNτ), transforming growth factor β1 (TGFB1) and secreted seminal-vesicle Ly-6 protein 1 (SSLP1) gene expression was greater in BCB+ than in BCB- blastocysts. By contrast, Bcl2-associated X protein (BAX) and heterogeneous nuclear ribonucleoprotein A2/B1 (HNRNPA2B1) gene expression was greater in BCB- than in BCB+ and control embryos. In conclusion, oocyte-derived embryos selected on the basis of BCB staining showed differences in developmental rate, quality, mitochondrial content and target gene expression compared to control embryos.