Ultrastructural study of Haematococcus lacustris (Girod.) Rostafinski (Volvocales). II: Mitosis and cytokinesis
Ultrastructural study of Haematococcus lacustris (Girod.) Rostafinski (Volvocales). II: Mitosis and cytokinesis
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DOI：
10.1508/cytologia.49.229
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发表时间：
1984
期刊：
影响因子：
1
通讯作者：
J. Mesquita;M. F. Santos
中科院分区：
文献类型：
--
作者：
J. Mesquita;M. F. Santos
本文报道了乳红球藻细胞分裂的超微结构研究结果。更有意义的数据如下：核膜几乎在整个有丝分裂过程中保持完整，因为只有在子核分离的末期，核膜才会破裂。在间期细胞核中显示两种典型结构成分(颗粒状和纤维状)的核仁的消失有时是延迟的，因为在中后期-后期观察到明显有组织的核仁。纺锤体微管似乎只起源于核内，因为它们既不通过极窗，也不通过核孔，似乎与核外结构有关。中期和后期可见上述核内纺锤体是由“连续”的和染色体组成的。前者持续存在于带间区域直至末期，后者位于染色质深处，有时位于明显分化的染色体区域(着丝粒)。在后期-末期早期，细胞核更细长，有时弯曲，末端反复扩张(哑铃形)。末期核的核膜在中间区域破裂，围绕着两个染色体群(子核)。在它们之间，一个不断增长的分裂沟(质膜内陷)结束，导致原生质体分裂(胞质分裂)。这种分裂沟总是与微管系统(藻类)联系在一起，类似于在其他藻类中所描述的。
In this article are presented the results of the ultrastructural study of the cell division in Haematococcus lacustris. The more significative data are as follows: the nuclear envelope is maintained intact practically throughout mitosis, as it only breaks down at the end of telophase when the daughter nuclei are separated. The disappearance of the nucleolus, which in the interphase nuclei display the two typical structural components (granulous and fibrillar), is sometimes delayed, since in late metaphase-early anaphase nucleolus clearly organised were observed. The spindle microtubules (NITS) seem to have an exclusively endonuclear origin, as neither through polar fenestrae nor nuclear pores they appear to be related with any extranuclear structure. In metaphase and anaphase we can see that the above endonuclear spindle is formed by “continuous” and chromosomic MTS. The former are persistent in the interzonal region up to telophase and the latter are deep in the chromatin, sometimes in apparently differentiated chromosomic regions (centromeres). In late anaphase-early telophase, the nucleus is seen more elongated, sometimes curved and repeatedly with dilated ends (dumbell shaped). The nuclear envelope of the telophasic nucleus breaks down in the middle-region and surrounds the two chromosomic groups (daughter nuclei). Between them, a growing cleavage furrow (invagination of the plasmalemma) ends by leading to the division of the protoplast (cytokinesis). This cleavage furrow is always associated to a microtubular system (phycoplast) similar to that which has been described in other algae.