Ito Hidetaka, Miura Asuka, Takashima Kazuya, Kakutani Tetsuji
Department of Integrated Genetics, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan.
Mol Genet Genomics. 2007 Jan;277(1):23-30. doi: 10.1007/s00438-006-0172-2. Epub 2006 Oct 11.
Despite the conserved roles and conserved protein machineries of centromeres, their nucleotide sequences can be highly diverse even among related species. The diversity reflects rapid evolution, but the underlying mechanism is largely unknown. One approach to monitor rapid evolution is examination of intra-specific variation. Here we report variant centromeric satellites of Arabidopsis thaliana found through survey of 103 natural accessions (ecotypes). Among them, a cluster of variant centromeric satellites was detected in one ecotype, Cape Verde Islands (Cvi). Recombinant inbred mapping revealed that the variant satellites are distributed in centromeric region of the chromosome 5 (CEN5) of this ecotype. This apparently recent variant accumulation is associated with large deletion of a pericentromeric region and the expansion of satellite region. The variant satellite was bound to HTR12 (centromeric variant histone H3), although expansion of the satellite was not associated with comparable increase in the HTR12 binding. The results suggest that variant satellites with centromere function can rapidly accumulate in one centromere, supporting the model that the satellite repeats in the array are homogenized by occasional unequal crossing-over, which has a potential to generate an expansion of local sequence variants within a centromere cluster.
尽管着丝粒具有保守的功能和保守的蛋白质机制，但其核苷酸序列即使在亲缘关系相近的物种之间也可能高度多样化。这种多样性反映了快速进化，但其潜在机制在很大程度上尚不清楚。监测快速进化的一种方法是检查种内变异。在这里，我们报告了通过对103个自然生态型（生态型）进行调查发现的拟南芥变异着丝粒卫星。其中，在一个生态型佛得角群岛（Cvi）中检测到一组变异着丝粒卫星。重组自交系定位显示，变异卫星分布在该生态型染色体5（CEN5）的着丝粒区域。这种明显近期的变异积累与着丝粒周围区域的大量缺失和卫星区域的扩张有关。变异卫星与HTR12（着丝粒变异组蛋白H3）结合，尽管卫星的扩张与HTR12结合的相应增加无关。结果表明，具有着丝粒功能的变异卫星可以在一个着丝粒中快速积累，支持了阵列中的卫星重复序列通过偶尔的不等交换而同质化的模型，这有可能在着丝粒簇内产生局部序列变异的扩张。
