Zahner J E, Cheney C M
Department of Genetics, Washington University School of Medicine, St. Louis 63110.
Dev Genet. 1990;11(1):27-40. doi: 10.1002/dvg.1020110105.
The Drosophila mutation, quartet, affects development at points in the life cycle that require intense mitotic activity. Examination of embryos affected by the maternal effect of quartet has revealed defects that can be attributed to incomplete chromosome separation at mitosis. These defects include uneven spacing of nuclei, strands of DNA creating bridges between nuclei, and abnormal amounts of DNA per nucleus. Nuclei in quartet-affected embryos also have a greater-than-normal number of centrosomes. Immunofluorescent examination of the spindles in quartet-affected embryos has revealed tripolar spindles and adjacent spindles that share a common spindle pole. Finally, chromosome separation distance was measured in anaphase and telophase spindles in quartet-affected embryos and found to be blocked in anaphase. Examination of mitotic figures in quartet larvae revealed a reduced mitotic index and an elevated frequency of abnormal mitotic figures. quartet could encode a function necessary for the disengagement of chromosomes in mitosis, for kinetochore function or for function of a spindle motor. Mutations in quartet prevent the post-translational modification of three abundant proteins. These proteins may be involved in chromosome separation in mitosis.
果蝇突变体“四重奏”影响生命周期中需要强烈有丝分裂活动的阶段的发育。对受“四重奏”母体效应影响的胚胎进行检查后发现，缺陷可归因于有丝分裂时染色体分离不完全。这些缺陷包括细胞核间距不均、形成细胞核间桥的DNA链以及每个细胞核中异常数量的DNA。受“四重奏”影响的胚胎中的细胞核也有比正常数量更多的中心体。对受“四重奏”影响的胚胎中的纺锤体进行免疫荧光检查，发现了三极纺锤体和共享共同纺锤极的相邻纺锤体。最后，在受“四重奏”影响的胚胎的后期和末期纺锤体中测量了染色体分离距离，发现其在后期受阻。对“四重奏”幼虫的有丝分裂图像进行检查，发现有丝分裂指数降低，异常有丝分裂图像的频率升高。“四重奏”可能编码有丝分裂中染色体分离、动粒功能或纺锤体马达功能所需的一种功能。“四重奏”中的突变会阻止三种丰富蛋白质的翻译后修饰。这些蛋白质可能参与有丝分裂中的染色体分离。
