Cytoskeletal studies of peculiar mitoses during male gametogenesis of angiosperms using immunofluorescence methods.

在长角草属植物雄配子发生过程中，先后发生了小孢子细胞核迁移、小孢子不均等分裂、生殖细胞与营养细胞分化以及花粉管生殖细胞分裂等特殊的细胞分裂和分化事件。用免疫荧光法和抑制实验研究了微管、肌动蛋白和肌球蛋白与这些事件的关系。紫露草小孢子核在分裂前发生两次迁移。第二次核迁移对不平等分裂至关重要，依赖于Nffs，但第一次是独立的。在小孢子分裂过程中，线粒体形成不对称的纺锤体和成膜体。MT介导生殖细胞的伸长，但不介导花粉管的伸长。虾脊兰等植物生殖细胞分裂中的纺锤体是一种特殊的构型，即中期染色体沿着纺锤体轴和姐妹染色体串联排列 关于我们 在分裂后期，纺锤体伸长使染色体反方向分离。在小孢子中未发现与核迁移或不均等分裂有关的肌动蛋白。F-actin仅存在于成膜体中。小孢子分裂后，在营养核的两侧横向上，F-肌动蛋白被组织起来，并在成熟花粉粒中发育成丰富的复杂网络。这种F-肌动蛋白在花粉管生长或细胞质流动中起重要作用，但在生殖细胞分裂中不起作用。总之，不同的动态之间的MT和肌动蛋白在男性配子发生进行了检查。肌球蛋白主要分布在生殖细胞和营养细胞的细胞器表面。弗吉尼亚和其他两个物种。N-乙基马来酰亚胺，肌动球蛋白ATP酶活性的抑制剂，这些和营养细胞核在花粉管中的迁移，以及管的生长，受到抑制。有迹象表明，他们的迁移力是由肌动球蛋白系统产生的，尽管正在进一步研究肌球蛋白是否存在于营养细胞核中。少

During the male gametogenesis of anglospenns, some peculiar events concerning cell division and differentiation successively occur ; nuclear migration in microspore cell, unequal division of microspore, differentiation between generative and vegetative cells and generative cell division in pollen tube. The associations of microtubules (Ws), actin and myosin with these events were studied using immlmofluo-rescence methods and inhibitory experiments. In Tradescantia paludosa, microspore nuclei migrated twice before the division. The second nuclear migration, essential to the unequal division, was dependent on Nffs, but the first was independent. MTs constructed asymmetric mitotic spindle and phragmoplast in microspore division. MTs mediated generative cell elongation but not pollen tube elongation. The spindles in generative cell divisions of Calanthe and some other species were peculiar configurations in which metaphase chromosomes lay in tandem along the spindle axis and sister chromos … More omes separated anti-parallelly by spindle elongation during anaphase. No F-actin associating with the nuclear migrations or unequal division was found in microspores. Distinct F-actin was found only in the phragmoplast. F-actin was organized on both transverse sides of the vegetative nucleus after microspore division, and developed into an abundant complex network in mature pollen grains. This F-actin played an important role in pollen tube growth or cytoplasmic streaming, but not in generative cell division. In conclusion, the different dynamics between MTs and actin during male gametogenesis were examined. Myosin was detected on the surface of generative cells and vegetative cell organelles of T. virginiana and two other species. The migration of these and of vegetative nuclei within pollen tubes, as well as tube growth, were inhibited by N-ethylmaleimide, an inhibitor of actomyosin ATPase activity. Indications were that the force for their migration was produced by an actomyosin system, although further research is underway on the subject of whether or not myosin is present in vegetative nuclei. Less