This study investigated the effect of melatonin (MT) on cell cycle (G1/S/G2/M) of parthenogenetic zygotes developed from vitrified-warmed mouse metaphase II (MII) oocytes and elucidated the potential mechanism of MT action in the first cleavage of embryos. After vitrification and warming, oocytes were parthenogenetically activated (PA) and in vitro cultured (IVC). Then the spindle morphology and chromosome segregation in oocytes, the maternal mRNA levels of genes including Miss, Doc1r, Setd2 and Ythdf2 in activated oocytes, pronuclear formation, the S phase duration in zygotes, mitochondrial function at G1 phase, reactive oxygen species (ROS) level at S phase, DNA damage at G2 phase, early apoptosis in 2-cell embryos, cleavage and blastocyst formation rates were evaluated. The results indicated that the vitrification/warming procedures led to following perturbations 1) spindle abnormalities and chromosome misalignment, alteration of maternal mRNAs and delay in pronucleus formation, 2) decreased mitochondrial membrane potential (MMP) and lower adenosine triphosphate (ATP) levels, increased ROS production and DNA damage, G1/S and S/G2 phase transition delay, and delayed first cleavage, and 3) increased early apoptosis and lower levels of cleavage and blastocyst formation. Our results further revealed that such negative impacts of oocyte cryopreservation could be alleviated by supplementation of warming, recovery, PA and IVC media with 10− 9 mol/L MT before the embryos moved into the 2-cell stage of development. MT might promote cell cycle progression via regulation of MMP, ATP, ROS and maternal mRNA levels, potentially increasing the first cleavage of parthenogenetic zygotes developed from vitrified–warmed mouse oocytes and their subsequent development.

中文翻译：

---

褪黑激素可能通过促进细胞周期进程来改善玻璃化加热小鼠卵母细胞孤雌生殖胚胎的第一次分裂

本研究调查了褪黑激素 (MT) 对从玻璃化加热的小鼠中期 II (MII) 卵母细胞发育的孤雌生殖受精卵的细胞周期 (G1/S/G2/M) 的影响，并阐明了 MT 在第一次卵裂中的潜在作用机制。胚胎。在玻璃化和加温后，卵母细胞被孤雌生殖激活 (PA) 和体外培养 (IVC)。然后卵母细胞纺锤体形态和染色体分离，激活卵母细胞中 Miss、Doc1r、Setd2 和 Ythdf2 等基因的母体 mRNA 水平，原核形成，受精卵 S 期持续时间，G1 期线粒体功能，活性氧 (ROS)评估了 S 期的水平、G2 期的 DNA 损伤、2 细胞胚胎的早期凋亡、卵裂和囊胚形成率。结果表明，玻璃化冷冻/加温程序导致以下扰动 1) 纺锤体异常和染色体错位、母体 mRNA 改变和原核形成延迟，2) 降低线粒体膜电位 (MMP) 和降低三磷酸腺苷 (ATP) 水平，增加ROS 产生和 DNA 损伤、G1/S 和 S/G2 相变延迟，以及延迟第一次卵裂，以及 3) 增加早期细胞凋亡和降低卵裂和囊胚形成水平。我们的结果进一步表明，在胚胎进入 2 细胞发育阶段之前，可以通过补充 10-9 mol/L MT 的加温、恢复、PA 和 IVC 培养基来减轻卵母细胞冷冻保存的这种负面影响。MT 可能通过调节 MMP、ATP、ROS 和母体 mRNA 水平来促进细胞周期进程，