Murakami S, Niwa O
Department of Biophysics, Faculty of Science, Kyoto University, Japan.
Mol Gen Genet. 1995 Dec 10;249(4):391-9. doi: 10.1007/BF00287100.
Cytological observations have shown that the presence of unstable minichromosomes can delay progression through the early stages of mitosis in fission yeast (Schizosaccharomyces pombe), suggesting that such minichromosomes may provide a useful tool for examining the system that regulates the coordinated segregation of chromosomes. One such unstable minichromosome is a large circular minichromosome. We previously showed that the mitotic instability of this minichromosome is probably due to the frequent occurrence of catenated forms of DNA after replication. To identify genes involved in the regulation of chromosome behavior in mitosis, we isolated mutants which stabilized this minichromosome. Three loci (sta1, sta2, and sta3) were identified. Two of them were found to be suppressors of temperature-sensitive mutations in cdc2, which encodes the catalytic subunit of muturation promoting factor (MPF). They show no linkage to, and are thus different from, suc1, and cdc13, previously identified as genes that interact with cdc2. The other mutation mapped to a gene previously identified as being required for the correct formation of the mitotic spindle. Data provided in this study suggest that the sta genes are involved in the regulation of spindle dynamics to ensure proper chromosome segregation during mitosis.
细胞学观察表明，不稳定的微型染色体的存在会延迟裂殖酵母（粟酒裂殖酵母）有丝分裂早期的进程，这表明此类微型染色体可能为研究调控染色体协调分离的系统提供有用的工具。一种这样的不稳定微型染色体是大型环状微型染色体。我们之前表明，这种微型染色体的有丝分裂不稳定性可能是由于复制后频繁出现DNA连环体形式。为了鉴定参与有丝分裂中染色体行为调控的基因，我们分离出了使这种微型染色体稳定的突变体。鉴定出了三个基因座（sta1、sta2和sta3）。其中两个被发现是cdc2温度敏感突变的抑制子，cdc2编码成熟促进因子（MPF）的催化亚基。它们与之前鉴定为与cdc2相互作用的基因suc1和cdc13没有连锁关系，因此有所不同。另一个突变定位于一个之前鉴定为有丝分裂纺锤体正确形成所必需的基因。本研究提供的数据表明，sta基因参与纺锤体动力学调控，以确保有丝分裂期间染色体的正确分离。
