He Honghong, Zhang Huizhu, Li Qin, Fan Jiangfeng, Pan Yangyang, Zhang Tongxiang, Robert Niayale, Zhao Ling, Hu Xuequan, Han Xiaohong, Yang Shanshan, Cui Yan, Yu Sijiu
Gansu Province Livestock Embryo Engineering Research Center, College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China.
Gansu Province Livestock Embryo Engineering Research Center, College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China.
Theriogenology. 2020 Oct 15;156:46-58. doi: 10.1016/j.theriogenology.2020.06.022. Epub 2020 Jun 28.
Mammalian oocyte maturation and early embryo development are highly sensitive to the in vitro culture environment, and oxygen concentration is one of the important factors. In the present study, we aimed to explore the effects of different oxygen concentrations (20%, 10%, 5% or 1% O) on yak oocyte maturation, in vitro fertilization (IVF), and embryo development competence, as well as its effects on the oxidative response, metabolism, and apoptosis in cumulus-oocyte complexes (COCs) and the embryo. The results revealed that the maturation rate of oocytes, blastocysts rate and hatched blastocysts rate in the group with 5% oxygen concentration were significantly higher (P < 0.05) than other groups, but the cleavage rate with 5% oxygen concentration was significantly lower (P < 0.05) than the 20% and 10% oxygen concentrations. The maturation rate of oocytes, the cleavage rate, blastocysts rate and hatched blastocysts rate with the 1% oxygen concentration were the lowest. The blastocyst cultured with 5% oxygen concentration had significantly greater (P < 0.05) numbers of total cells, inner cell mass (ICM) cells and trophectoderm (TE) cells compared to the other groups. Analysis of the apoptosis index of oocytes and blastocyst cells by transferase dUTP nick end labeling (TUNEL) showed that the number of apoptotic cells significantly reduced (P < 0.05) with 5% oxygen concentration, but increased significantly (P < 0.05) in the 1% oxygen concentration group. Also, the qRT-PCR and western immunoblotting analysis confirmed that the transcription levels of the metabolism genes, antioxidant response genes, apoptosis genes, oocyte competence genes and embryonic developmental markers showed significant differences (P < 0.05) in the COCs or blastocysts matured in 5% oxygen concentration group compared to the other groups. In summary, our findings demonstrate that 5% oxygen concentration improves oocyte maturation and blastocyst development in the yak, increases blastocyst cell numbers, reduces apoptosis rate in the oocyte and blastocyst as well as reduces embryo cleavage rate.
哺乳动物卵母细胞成熟和早期胚胎发育对体外培养环境高度敏感，而氧气浓度是重要因素之一。在本研究中，我们旨在探讨不同氧气浓度（20%、10%、5%或1% O₂）对牦牛卵母细胞成熟、体外受精（IVF）及胚胎发育能力的影响，以及其对卵丘 - 卵母细胞复合体（COCs）和胚胎中氧化反应、代谢及细胞凋亡的影响。结果显示，氧气浓度为5%组的卵母细胞成熟率、囊胚率和孵化囊胚率显著高于其他组（P < 0.05），但5%氧气浓度组的卵裂率显著低于20%和10%氧气浓度组（P < 0.05）。氧气浓度为1%组的卵母细胞成熟率、卵裂率、囊胚率和孵化囊胚率最低。与其他组相比，5%氧气浓度培养的囊胚总细胞数、内细胞团（ICM）细胞数和滋养外胚层（TE）细胞数显著更多（P < 0.05）。通过末端脱氧核苷酸转移酶介导的dUTP缺口末端标记法（TUNEL）分析卵母细胞和囊胚细胞的凋亡指数表明，5%氧气浓度组的凋亡细胞数显著减少（P < 0.05），而1%氧气浓度组显著增加（P < 0.05）。此外，qRT - PCR和蛋白质免疫印迹分析证实，与其他组相比，在5%氧气浓度下成熟的COCs或囊胚中，代谢基因、抗氧化反应基因、凋亡基因、卵母细胞能力基因和胚胎发育标志物的转录水平存在显著差异（P < 0.05）。总之，我们的研究结果表明，5%氧气浓度可改善牦牛卵母细胞成熟和囊胚发育，增加囊胚细胞数量，降低卵母细胞和囊胚的凋亡率，并降低胚胎卵裂率。
