Sericin supplementation during in vitro culture enhances the developmental competence of heat stressed bovine embryos

抄録

The silk protein sericin has been identified as a potent antioxidant in mammalian cells. In this study, we investigated the potential effects of sericin supplementation during in vitro culture (IVC) medium on subsequent embryonic development and quality of bovine embryos exposed to heat stress (HS). After in vitro fertilization, putative zygotes were cultured in medium supplemented with sericin and subjected for 6 h heat stress at 40.5°C on day 2 or day 7 followed by 38.5°C until day 8. After IVC, the developmental rate to blastocysts, total cell number, and the percentage of apoptotic cells in blastocysts were evaluated on day 8 (day 0, IVF day). Intracellular reactive oxygen species (ROS) level of embryos were detected just after heat stress on day 2 and day 7. The developmental rate to blastocysts and total cell number of blastocysts were significantly (P < 0.05) reduced in HS-group. In addition, the number of TUNEL-positive cells and ROS level of embryos in HS-group were significantly (P < 0.01) increased compared with those of control group. On the other hand, supplementation of 0.1 % sericin significantly (P < 0.05) increased the developmental rate and quality of heat stressed embryos by decreasing the ROS levels and TUNEL-positive cells. Our findings indicate that sericin application effectively protects the embryos from HS and increases the developmental competence of preimplantation bovine embryos.