Abnormal distribution of chromosomes in the first division of nuclear transferred mouse embryos
Abnormal distribution of chromosomes in the first division of nuclear transferred mouse embryos
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DOI：
10.1262/jrd.19007
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发表时间：
2007-06-01
影响因子：
1.8
通讯作者：
Hosoi, Yoshihiko
中科院分区：
文献类型：
--
作者：
Kawasumi, Miyuri;Anzai, Masayuki;Hosoi, Yoshihiko
大多数体细胞核移植胚胎在着床前或着床后死亡。许多研究都集中在核移植早期供体核的形态重塑及其相关的细胞骨架结构上。然而，对于SCNT胚胎第一次分裂后的2细胞阶段知之甚少。在本研究中，我们比较了SCNT胚胎在1细胞期至2细胞期染色体分裂的形态学状态与卵浆内单精子注射（ICSI）胚胎。尽管SCNT和ICSI胚胎中第一个有丝分裂纺锤体的形成是正常的，但与染色质分离有关的微管和细胞质母粒在原核阶段消失了。然而，在30%的2细胞SCNT胚胎和12%的2细胞ICSI胚胎中观察到核断裂。这些胚胎的两个卵裂球都存在核碎裂。在SCNT或ICSI胚胎中，tdt介导的dutp -生物素尼克末端标记（TUNEL）检测未观察到凋亡DNA片段。在SCNT和ICSI胚胎中，在从1细胞阶段分裂到2细胞阶段的过程中，第一个有丝分裂纺锤体中的染色体分布都受到了干扰。这些结果表明，SCNT胚胎在着床前或着床后的丢失可能是由于2细胞期染色体分布异常所致。
The majority of somatic cell nuclear transferred (SCNT) embryos die before or after implantation. Many studies have focused on morphological remodeling of the donor nucleus and its associated cytoskeletal structures in the early events of nuclear transfer. However, little is known about the 2-cell stage of SCNT embryos after the first division. In this study, we compared the morphological status of chromosomal division during the 1-cell stage to the 2-cell stage in SCNT embryos with that in intracytoplasmic sperm injection (ICSI) embryos. The microtubules and cytoplasmic asters, which are related to chromatin segregation, disappeared at the pronuclear stage, although formation of the first mitotic spindle was normal in both the SCNT and ICSI embryos. However, nuclear fragmentation was observed in 30% of the 2-cell SCNT embryos and 12% of the 2-cell ICSI embryos. Nuclear fragmentation was present in both blastomeres of these embryos. No apoptotic DNA fragmentation was observed in TdT-mediated dUTP-biotin Nick End Labeling (TUNEL) assays for either the SCNT or ICSI embryos. In both the SCNT and ICSI embryos, the distribution of chromosomes in the first mitotic spindle was disturbed during the process of division from the 1-cell stage to the 2-cell stage. These results suggest that loss of SCNT embryos just before or after implantation may be due to an abnormal chromosome distribution at the 2-cell stage.