Li Haijuan
College of Biological and Environmental Engineering, Xi'an University, Xi'an 710065, Shaanxi, China
G3 (Bethesda). 2019 Apr 9;9(4):1249-1261. doi: 10.1534/g3.119.400086.
Little is known about chromosome segregation in polyploid prokaryotes. In this study, whether stringent or variable chromosome segregation occurs in polyploid thermophilic bacterium was analyzed. A stable heterozygous strain (HL01) containing two antibiotic resistance markers at one gene locus was generated. The inheritance of the two alleles in the progeny of the heterozygous strain was then followed. During incubation without selection pressure, the fraction of heterozygous cells decreased and that of homozygous cells increased, while the relative abundance of each allele in the whole population remained constant, suggesting chromosome segregation had experienced random event. Consistently, in comparison with in which the sister chromosomes were segregated equally, the ratios of DNA content in two daughter cells of had a broader distribution and a larger standard deviation, indicating that the DNA content in the two daughter cells was not always identical. Further, the protein homologs (, ParA and MreB) which have been suggested to be involved in bacterial chromosome partitioning did not actively participate in the chromosome segregation in Therefore, it seems that protein-based chromosome segregation machineries are less critical for the polyploid , and chromosome segregation in this bacterium are not stringently controlled but tend to be variable, and random segregation can occur.
关于多倍体原核生物中的染色体分离，人们了解甚少。在本研究中，分析了多倍体嗜热细菌中是否发生严格或可变的染色体分离。构建了一个在一个基因位点含有两个抗生素抗性标记的稳定杂合菌株（HL01）。然后追踪杂合菌株子代中两个等位基因的遗传情况。在无选择压力的培养过程中，杂合细胞的比例下降，纯合细胞的比例上升，而整个群体中每个等位基因的相对丰度保持不变，这表明染色体分离经历了随机事件。一致地，与姐妹染色体平均分离的情况相比，该菌两个子细胞中的DNA含量比值分布更宽且标准差更大，表明两个子细胞中的DNA含量并不总是相同的。此外，已被认为参与细菌染色体分配的蛋白质同源物（如ParA和MreB）并未积极参与该菌的染色体分离。因此，基于蛋白质的染色体分离机制对多倍体该菌似乎不太关键，并且该细菌中的染色体分离并非严格受控，而是倾向于可变的，并且可能发生随机分离。
