Department of Embryology, Camel Advanced Reproductive Technologies Centre, Government of Dubai, Dubai, United Arab Emirates.
Department of Animal Production, College of Food and Agricultural Sciences, King Saud University, 11451 Riyadh, Saudi Arabia.
Zygote. 2021 Oct;29(5):383-392. doi: 10.1017/S0967199421000150. Epub 2021 Mar 18.
Oocyte cryopreservation has become an important component of assisted reproductive technology with increasing implication in female fertility preservation and animal reproduction. However, the possible adverse effects of oocyte cryopreservation on epigenetic status of the resulting embryos is still an open question. This study evaluated the effects of MII-oocyte vitrification on gene transcripts linked to epigenetic reprogramming in association with the developmental competence and epigenetic status of the resulting embryos at 2-cell and blastocyst stages in dromedary camel. The cleavage rate of vitrified oocytes following intracytoplasmic sperm injection was significantly increased compared with the control (98.2 ± 2 vs. 72.7 ± 4.1%, respectively), possibly due to the higher susceptibility of vitrified oocytes to spontaneous activation. Nonetheless, the competence of cleaved embryos derived from vitrified oocytes for development to the blastocyst and hatched blastocyst was significantly reduced compared with the control (7.7 ± 1.2 and 11.1 ± 11.1 compared with 28.1 ± 2.6 and 52.4 ± 9.9%, respectively). The relative transcript abundances of epigenetic reprogramming genes DNMT1, DNMT3B, HDAC1, and SUV39H1 were all significantly reduced in vitrified oocytes relative to the control. Evaluation of the epigenetic marks showed significant reductions in the levels of DNA methylation (6.1 ± 0.3 vs. 9.9 ± 0.5, respectively) and H3K9 acetylation (7.8 ± 0.2 vs. 10.7 ± 0.3, respectively) in 2-cell embryos in the vitrification group relative to the control. Development to the blastocyst stage partially adjusted the effects that oocyte vitrification had on the epigenetic status of embryos (DNA methylation: 4.9 ± 0.4 vs. 6.2 ± 0.6; H3K9 acetylation: 5.8 ± 0.3 vs. 8 ± 0.9, respectively). To conclude, oocyte vitrification may interfere with the critical stages of epigenetic reprogramming during preimplantation embryo development.
卵母细胞冷冻保存已成为辅助生殖技术的重要组成部分，对女性生育力保存和动物繁殖的影响越来越大。然而，卵母细胞冷冻保存对胚胎表观遗传状态的可能不利影响仍然是一个悬而未决的问题。本研究评估了 MII 期卵母细胞玻璃化对与骆驼 2 细胞和囊胚阶段胚胎发育能力和表观遗传状态相关的表观遗传重编程相关基因转录本的影响。与对照组相比，玻璃化卵母细胞经胞质内精子注射后的卵裂率显著增加（分别为 98.2%±2%和 72.7%±4.1%），这可能是由于玻璃化卵母细胞对自发激活的敏感性更高。尽管如此，与对照组相比，来自玻璃化卵母细胞的卵裂胚胎发育为囊胚和孵化囊胚的能力显著降低（分别为 7.7%±1.2%和 11.1%±11.1%与 28.1%±2.6%和 52.4%±9.9%）。与对照组相比，表观遗传重编程基因 DNMT1、DNMT3B、HDAC1 和 SUV39H1 的相对转录丰度在玻璃化卵母细胞中均显著降低。对表观遗传标记的评估表明，玻璃化组 2 细胞胚胎中的 DNA 甲基化水平（分别为 6.1%±0.3%和 9.9%±0.5%）和 H3K9 乙酰化水平（分别为 7.8%±0.2%和 10.7%±0.3%）均显著降低。在胚胎发育到囊胚阶段时，卵母细胞玻璃化对胚胎表观遗传状态的影响部分得到了调整（DNA 甲基化：4.9%±0.4%与 6.2%±0.6%；H3K9 乙酰化：5.8%±0.3%与 8%±0.9%）。总之，卵母细胞玻璃化可能会干扰胚胎植入前发育过程中关键的表观遗传重编程阶段。
