Effect of sericin on preimplantation development of bovine embryos cultured individually

The silk protein sericin has been identified as a potent antioxidant in mammalian cells. This study was conducted to examine the effects of sericin on preimplantation development and quality of bovine embryos cultured individually. When two-cell-stage embryos were cultured individually for 7 days in CR1aa medium supplemented with 0, 0.1, 0.5, or 1% sericin, rates of total blastocyst formation and development to expanded blastocysts from embryos cultured with 0.5% sericin were higher (P < 0.05) than those from embryos cultured with 0 or 1% sericin. When embryos were cultured individually for 7 days in the CR1aa medium supplemented with 0 or 0.5% sericin under two oxidative stress conditions (50 or 100 μm H2O2), the addition of sericin significantly improved the blastocyst formation rate of embryos exposed to 100 μm H2O2. However, the protective effect of sericin was not observed in development of embryos exposed to 50 μm H2O2. When embryos were exposed to 100 μm H2O2 during culture, the DNA fragmentation index of total blastocysts from embryos cultured with 0.5% sericin was lower than blastocysts derived from embryos cultured without sericin (4.4 vs. 6.8%; P < 0.01). In conclusion, the addition of 0.5% sericin to in vitro culture medium improved preimplantation development and quality of bovine embryos cultured individually by preventing oxidative stress.