SummaryOocyte 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.

中文翻译：

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卵母细胞玻璃化导致使用 ICSI 在单峰骆驼中获得的胚胎中 DNA 甲基化和组蛋白乙酰化的丧失

摘要卵母细胞冷冻保存已成为辅助生殖技术的重要组成部分，在女性生育力保存和动物繁殖中的意义越来越大。然而，卵母细胞冷冻保存对所得胚胎的表观遗传状态可能产生的不利影响仍然是一个悬而未决的问题。本研究评估了 MII 卵母细胞玻璃化对与表观遗传重编程相关的基因转录物的影响，与单峰骆驼在 2 细胞和囊胚阶段所得胚胎的发育能力和表观遗传状态相关。与对照相比，胞浆内精子注射后玻璃化卵母细胞的切割率显着增加（分别为 98.2 ± 2 对 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，与对照相比，来自玻璃化卵母细胞的裂解胚胎发育成囊胚和孵化囊胚的能力显着降低（分别为 7.7 ± 1.2 和 11.1 ± 11.1，而分别为 28.1 ± 2.6 和 52.4 ± 9.9%）。表观遗传重编程基因的相对转录本丰度DNMT1,DNMT3B,HDAC1， 和SUV39H1相对于对照，玻璃化卵母细胞均显着减少。表观遗传标记的评估显示，玻璃化组中 2 细胞胚胎的 DNA 甲基化水平（分别为 6.1 ± 0.3 对 9.9 ± 0.5）和 H3K9 乙酰化水平（分别为 7.8 ± 0.2 对 10.7 ± 0.3）显着降低相对于控件。发育到囊胚阶段部分地调整了卵母细胞玻璃化对胚胎表观遗传状态的影响（DNA甲基化：4.9 ± 0.4 vs. 6.2 ± 0.6；H3K9乙酰化：分别为5.8 ± 0.3 vs. 8 ± 0.9）。总之，卵母细胞玻璃化可能会干扰植入前胚胎发育过程中表观遗传重编程的关键阶段。