Primate Research Institute, Kyoto University, Inuyama City, Japan.
Genome. 2012 Nov;55(11):809-12. doi: 10.1139/gen-2012-0123. Epub 2012 Nov 9.
The siamang (Symphalangus syndactylus), a species of the family Hylobatidae (gibbons), carries large blocks of constitutive heterochromatin in the telomere region of chromosomes. We recently found that alpha satellite DNA constitutes these heterochromatin blocks as a main component. Alpha satellite DNA, tandem repeat sequences of 171-bp repeat units, is a major component of centromeres in primates. In addition to the siamang, the white-cheeked gibbon (Nomascus leucogenys) was previously found to carry the alpha satellite DNA in the telomere region, although not as large a scale as the siamang. Gibbons comprise four genera: Hoolock, Hylobates, Nomascus, and Symphalangus. Here, we report that the amplification of alpha satellite DNA in the telomere region is probably confined to two genera: Nomascus and Symphalangus. We examined one species of Hoolock and four species of Hylobates and obtained evidence against such an amplification event in these species. The phylogenetic relationship of the four gibbon genera remains unclear. One simple explanation for the current distribution of the telomere region alpha satellite DNA would be that Nomascus and Symphalangus are relatively closely related and the amplification occurred in their common ancestor.
合趾猿（Symphalangus syndactylus），又称西白眉长臂猿，隶属于长臂猿科（猩猩科），其染色体端粒区域携带大量的结构异染色质。我们最近发现，α卫星 DNA 是这些异染色质块的主要组成部分。α卫星 DNA 是串联重复序列，由 171bp 的重复单元组成，是灵长类动物着丝粒的主要成分。除了合趾猿外，此前还发现白颊长臂猿（Nomascus leucogenys）在端粒区域携带α卫星 DNA，但规模不如合趾猿大。长臂猿属包括 4 个种：合趾猿、白掌长臂猿、白颊长臂猿和西白眉长臂猿。在这里，我们报告称，α卫星 DNA 在端粒区域的扩增可能仅限于两个种：白颊长臂猿和西白眉长臂猿。我们检查了 1 种合趾猿和 4 种白掌长臂猿，没有发现这些种中存在这种扩增事件的证据。四种长臂猿属的系统发育关系仍不清楚。对于当前端粒区域α卫星 DNA 的分布情况，一个简单的解释是，白颊长臂猿和西白眉长臂猿亲缘关系较近，扩增发生在它们的共同祖先中。
