Ehler L L, Dutcher S K
Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, 80309-0347, USA.
Cell Motil Cytoskeleton. 1998;40(2):193-207. doi: 10.1002/(SICI)1097-0169(1998)40:2<193::AID-CM8>3.0.CO;2-G.
In Chlamydomonas reinhardtii, specialized cytoskeletal structures known as rootlet microtubules are present throughout interphase and mitosis. During cytokinesis, an array of microtubules termed the phycoplast is nucleated from rootlet microtubules and forms coincidentally with the cleavage furrow [Johnson and Porter, 1968: J. Cell Biol. 38:403-425; Holmes and Dutcher, 1989: J. Cell Sci. 94:273-285; Gaffel and el-Gammel, 1990: Protoplasma 156:139-148; Schibler and Huang, 1991: J. Cell Biol. 113:605-614]. We have obtained two independent lines of evidence that support the hypothesis that the rootlet and phycoplast microtubules play a direct role in cleavage furrow placement and assembly. First, the destabilization of spindle and phycoplast microtubules by pharmacological agents was accompanied by the aberrant distribution of actin and a failure of cytokinesis. Second, we characterized mutant strains that failed to complete cytokinesis properly. Actin and myosin were mislocalized to additional rootlet microtubules in the cyt2-1 strain, and this mislocalization was correlated with the presence of additional cleavage furrows. This evidence suggests that microtubules are necessary for the correct positioning and assembly of functional cleavage furrows in C. reinhardtii.
在莱茵衣藻中，一种被称为根微管的特殊细胞骨架结构在整个间期和有丝分裂过程中均存在。在胞质分裂期间，一系列被称为藻质体的微管从根微管中形成，并与分裂沟同时形成[约翰逊和波特，1968年：《细胞生物学杂志》38:403 - 425；霍姆斯和达彻，1989年：《细胞科学杂志》94:273 - 285；加费尔和埃尔 - 加迈勒，1990年：《原生质体》156:139 - 148；施布勒和黄，1991年：《细胞生物学杂志》113:605 - 614]。我们获得了两条独立的证据，支持根微管和藻质体微管在分裂沟定位和组装中起直接作用这一假说。首先，药物制剂使纺锤体和藻质体微管不稳定，同时伴随着肌动蛋白分布异常和胞质分裂失败。其次，我们对未能正常完成胞质分裂的突变菌株进行了表征。在cyt2 - 1菌株中，肌动蛋白和肌球蛋白错误定位于额外的根微管，这种错误定位与额外分裂沟的存在相关。这一证据表明，微管对于莱茵衣藻中功能性分裂沟的正确定位和组装是必需的。
