Tianjin Institute of Animal Science and Veterinary Medicine, Tianjin, 300384, China.
College of Life Sciences, Nankai University, Tianjin, 300071, China.
Cell Biol Int. 2018 Sep;42(10):1401-1409. doi: 10.1002/cbin.11031. Epub 2018 Jul 31.
We investigated the dynamic changes in chromatin and microtubules at the first cell cycle in goat somatic cell nuclear transfer (SCNT)-derived and in vitro fertilization (IVF)-derived embryos. Stage-dependent and characteristic changes to chromatin and microtubules occurred in SCNT-derived embryos at different times after activation. About half donor nuclei underwent premature chromosome condensation (PCC) at 1 h post activation, and furtherly reached telophase at 2 h after activation. However, we discovered that the separated chromosomes reaggregated, not keeping two independent nuclei; and formed one pronucleus at 2.5 h after activation. One pronucleus was found in all reconstructed oocytes except other no nucleus oocytes from 3 to 22 h after activation. Reconstructed oocytes reached the first mitotic metaphase at 23 h post activation, which was later than that of IVF-derived embryos at 16 h after insemination. SCNT-derived embryos showed significantly higher abnormalities in the first mitotic metaphase spindle, compared with IVF-derived embryos. Abnormal spindles included multi polar and half spindles. SCNT-derived embryos began to cleave at 24 h after activation, which was later than that of IVF-derived embryos at 21 h after insemination. SCNT-derived embryos showed delayed conversion from telophase to interphase than IVF-derived embryos during cleavage. These might lead to poor development in SCNT-derived embryos.
我们研究了山羊体细胞核移植（SCNT）和体外受精（IVF）胚胎第一个细胞周期中染色质和微管的动态变化。在激活后不同时间，SCNT 胚胎中的染色质和微管发生了阶段依赖性和特征性变化。大约一半的供体核在激活后 1 小时发生过早染色体浓缩（PCC），并在激活后 2 小时进一步达到末期。然而，我们发现分离的染色体重新聚集，没有保持两个独立的核；并在激活后 2.5 小时形成一个原核。在激活后 3 至 22 小时，除了其他没有核的卵母细胞外，所有重构卵母细胞中都发现了一个原核。重构卵母细胞在激活后 23 小时达到第一次有丝分裂中期，这比受精后 16 小时的 IVF 胚胎晚。与 IVF 胚胎相比，SCNT 胚胎的第一次有丝分裂中期纺锤体异常明显更高。异常纺锤体包括多极和半纺锤体。SCNT 胚胎在激活后 24 小时开始分裂，比受精后 21 小时的 IVF 胚胎晚。SCNT 胚胎在分裂过程中从末期到间期的转换比 IVF 胚胎延迟。这可能导致 SCNT 胚胎发育不良。
