Department of Plant Anatomy and Cytology, Maria Curie-Skłodowska University, Akademicka 19, 20-033, Lublin, Poland.
Protoplasma. 2011 Apr;248(2):289-98. doi: 10.1007/s00709-010-0167-z. Epub 2010 Jun 11.
The actin cytoskeleton (microfilaments, MFs) accompanies the tubulin cytoskeleton (microtubules) during the meiotic division of the cell, but knowledge about the scope of their physiological competence and cooperation is insufficient. To cast more light on this issue, we analysed the F-actin distribution during the meiotic division of the Psilotum nudum sporocytes. Unfixed sporangia of P. nudum were stained with rhodamine-phalloidin and 4',6-diamidino-2-phenylindole dihydrochloride, and we monitored the changes in the actin cytoskeleton and nuclear chromatin throughout sporogenesis. We observed that the actin cytoskeleton in meiotically dividing cells is not only part of the kariokinetic spindle and phragmoplast but it also forms a well-developed network in the cytoplasm present in all phases of meiosis. Moreover, in telophase I F-actin filaments formed short-lived phragmoplast, which was adjacent to the plasma membrane, exactly at the site of future cell wall formation. Additionally, the meiocytes were pre-treated with cytochalasin-B at a concentration that causes damage to the MFs. This facilitated observation of the effect of selective MFs damage on the course of meiosis and sporogenesis of P. nudum. Changes were observed that occurred in the cytochalasin-treated cells: the daughter nuclei were located abnormally close to each other, there was no formation of the equatorial plate of organelles and, consequently, meiosis did not occur normally. It seems possible that, if the actin cytoskeleton only is damaged, regular cytokinesis will not occur and, hence, no viable spores will be produced.
有丝分裂细胞的胞质分裂（微丝，MFs）伴随着微管细胞骨架（微管）的形成，然而人们对于它们的生理功能和协作范围的认识还远远不够。为了更深入地了解这个问题，我们分析了 Psilotum nudum 孢子母细胞减数分裂过程中的 F-actin 分布。用罗丹明鬼笔环肽和 4'，6-二脒基-2-苯吲哚二盐酸盐对未固定的 P. nudum 孢子囊进行染色，我们观察了整个孢子发生过程中，胞质分裂过程中核染色质和肌动蛋白细胞骨架的变化。结果显示，有丝分裂细胞中的肌动蛋白细胞骨架不仅是减数分裂的有丝分裂纺锤体和胞质分裂环的一部分，而且在减数分裂的所有阶段都形成了发达的细胞质网络。此外，在第一次减数分裂末期 I 期，F-actin 纤维形成了短暂的胞质分裂环，该环与质膜相邻，正好位于未来细胞壁形成的位置。此外，预先用细胞松弛素 B 处理减数分裂的花粉母细胞，浓度足以破坏 MFs。这有助于观察选择性破坏 MFs 对 P. nudum 减数分裂和孢子发生过程的影响。在细胞松弛素处理过的细胞中观察到了一些变化：子细胞核异常靠近彼此，没有形成赤道板细胞器，因此减数分裂不能正常进行。如果仅仅是肌动蛋白细胞骨架受到破坏，那么正常的胞质分裂就不会发生，因此也就不会产生有活力的孢子。
