Differential rates of local and global homogenization in centromere satellites from Arabidopsis relatives
Differential rates of local and global homogenization in centromere satellites from Arabidopsis relatives
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DOI：
10.1534/genetics.104.038208
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发表时间：
2005-08-01
期刊：
影响因子：
3.3
通讯作者：
Preuss, D
中科院分区：
文献类型：
--
作者：
Hall, SE;Luo, S;Preuss, D
高等真核生物着丝粒包含数千个组织成串联阵列的卫星重复序列。随着物种的分化，新的卫星变体在染色体内部和染色体之间均质化，但对特定序列分散的过程却知之甚少。在这里，我们分离并分析了与拟南芥分离5-2000万年的植物中的着丝粒卫星，发现与灵长类动物a卫星重复相比，卫星发散更快。我们还发现，来自相同基因组位点的卫星比来自不同基因组区域的卫星彼此更相似，这表明新的序列改变在局部水平而不是全局水平上更有效地同质化。尽管如此，与人类着丝粒中发现的类似的高阶卫星阵列的存在表明局部同质化的局限性，并表明序列多态性可能发挥重要的功能作用。在两个物种中，我们定义了更广泛的多态性，识别出物理上分离且高度不同的卫星类型。总而言之，这些数据表明植物卫星同质化和卫星变异的持久性之间存在平衡。这种平衡最终可能产生足够的序列分歧，导致植物物种之间的交配不相容，同时在物种内保持着丝粒活性的充分保护。
Higher eukaryotic centromeres contain thousands of satellite repeats organized into tandem arrays. As species diverge, new satellite variants are homogenized within and between chromosomes, yet the processes by which particular sequences are dispersed are poorly understood. Here, we isolated and analyzed centromere satellites in plants separated from Arabidopsis thaliana by 5-20 million years, uncovering more rapid satellite divergence compared to primate a-satellite repeats. We also found that satellites derived from the same genomic locus were more similar to each other than satellites derived from disparate genomic regions, indicating that new sequence alterations were homogenized more efficiently at a local, rather than global, level. Nonetheless, the presence of higher-order satellite arrays, similar to those identified in human centromeres, indicated limits to local homogenization and suggested that sequence polymorphisms may play important functional roles. In two species, we defined more extensive polymorphisms, identifying physically separated and highly distinct satellite types. Taken together, these data show that there is a balance between plant satellite homogenization and the persistence of satellite variants. This balance could ultimately generate sufficient sequence divergence to cause mating incompatibilities between plant species, while maintaining adequate conservation within a species for centromere activity.