Goday C, González-García J M, Esteban M R, Giovinazzo G, Pimpinelli S
Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
J Cell Biol. 1992 Jul;118(1):23-32. doi: 10.1083/jcb.118.1.23.
In Parascaris the mitotic chromosomes of gonial germline cells are holocentric and possess a continuous kinetochore along their entire length. By contrast, in meiotic cells, the centromeric activity is restricted to the heterochromatic tips where direct insertion of spindle microtubules into chromatin without any kinetochore plate is seen. In the presomatic cells of early embryos, which undergo heterochromatin elimination, only euchromatin shows kinetic activity. After developing a technique to separate the very resistant egg shell from the embryos, we studied the cell divisions during early embryogenesis by immunochemical and EM approaches. The results reported here show that in presomatic cells microtubules bind only the euchromatin where a continuous kinetochore plate is present. We also report observations suggesting that the binding of the long kinetochores to the mitotic spindle initiates to a limited number of sites and extends along the entire length, during chromosome condensation. The existence of different centromere stages in different cell types, rends Parascaris chromosomes a very good model to study centromere organization.
在副蛔虫中，生殖系原始生殖细胞的有丝分裂染色体是全着丝粒的，并且在其整个长度上都有连续的动粒。相比之下，在减数分裂细胞中，着丝粒活性仅限于异染色质末端，在那里可以看到纺锤体微管直接插入染色质，而没有任何动粒板。在经历异染色质消除的早期胚胎的体细胞前体细胞中，只有常染色质显示出动力学活性。在开发出一种将非常坚韧的卵壳与胚胎分离的技术后，我们通过免疫化学和电子显微镜方法研究了早期胚胎发生过程中的细胞分裂。此处报道的结果表明，在体细胞前体细胞中，微管仅与存在连续动粒板的常染色质结合。我们还报告了一些观察结果，表明在染色体浓缩过程中，长动粒与有丝分裂纺锤体的结合始于有限数量的位点，并沿整个长度延伸。不同细胞类型中存在不同的着丝粒阶段，这使得副蛔虫染色体成为研究着丝粒组织的一个非常好的模型。
