Collas P, Pinto-Correia C, Ponce de Leon F A, Robl J M
Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst 01003.
Biol Reprod. 1992 Mar;46(3):501-11. doi: 10.1095/biolreprod46.3.501.
We investigated the influence of the cell cycle stage of the nuclear donor on prematurely condensed chromatin (PCC) and spindle morphology and on chromosome constitution in rabbit nuclear transplant embryos. The configuration of PCC following nuclear transplantation with G1, early S, and late S phase donor nuclei (G1, early S, and late S transplants, respectively) was characterized in whole mounts and chromosome spreads. In addition, the influence of the donor cell cycle stage on chromosome constitution in cleavage stage-manipulated embryos was determined. Within 2 h after fusion of the donor blastomere, the recipient oocyte cytoplasm was able to induce formation de novo of a metaphase plate associated with a spindle in G1, early S, and late S transplants. Metaphase chromosomes and spindle were intact in most cases of PCC in G1 transplants. However, these structures displayed minor abnormalities in early S transplants and gross abnormalities in late S transplants, such as incomplete or absent spindle formation and incomplete chromatin condensation. Normal chromosomes were present in G1 and early S transplants, whereas chromosome abnormalities were detected in late S transplants. The results indicate that morphology of prematurely condensed G1 and early S chromatin has a minor influence on chromosome constitution of manipulated embryos. That of late S chromatin, however, affects chromosome constitution in embryos and may account for reduced development of nuclear transplant embryos when late S phase donor nuclei are used.
我们研究了核供体细胞周期阶段对兔核移植胚胎中早熟凝集染色质（PCC）、纺锤体形态及染色体组成的影响。通过整装片和染色体铺片对分别用G1期、早S期和晚S期供体细胞核进行核移植（分别称为G1移植、早S移植和晚S移植）后的PCC形态进行了表征。此外，还确定了供体细胞周期阶段对卵裂期操作胚胎染色体组成的影响。在供体卵裂球融合后2小时内，受体卵母细胞胞质能够在G1移植、早S移植和晚S移植中诱导重新形成与纺锤体相关的中期板。在G1移植的大多数PCC情况下，中期染色体和纺锤体是完整的。然而，这些结构在早S移植中显示出轻微异常，在晚S移植中则出现严重异常，如纺锤体形成不完全或缺失以及染色质凝集不完全。G1移植和早S移植中存在正常染色体，而晚S移植中检测到染色体异常。结果表明，早熟凝集的G1和早S染色质形态对操作胚胎的染色体组成影响较小。然而，晚S染色质的形态会影响胚胎的染色体组成，这可能是使用晚S期供体细胞核时核移植胚胎发育率降低 的原因。
