Primate Research Institute, Kyoto University, Inuyama, Japan.
J Hum Genet. 2013 Nov;58(11):752-4. doi: 10.1038/jhg.2013.87. Epub 2013 Aug 15.
Alpha satellite DNA (AS), a major DNA component of primate centromeres, is composed of a tandem array of repeat units of approximately 170 bp. The AS of hominids (family Hominidae; humans and great apes) includes sequences organized into higher-order repeat (HOR) structures, with a periodic appearance of multiple copies of the basic repeat units. Here, we identified an HOR in AS of the siamang, a small ape phylogenetically distinct from hominids but included in hominoids (superfamily Hominoidea). We sequenced long stretches of genomic DNA, and found a repetition of blocks consisting of six and four basic repeat units. Thus, AS organization into HOR is an attribute of hominoids, rather than, as currently postulated, hominids. In addition to centromeres, siamangs carry AS in terminal heterochromatin blocks, and it cannot be determined at present whether these HOR-containing AS sequences originate from the centromere or from the terminal heterochromatin. Even if the latter is the case, these sequences might affect the composition of centromeric AS by being transferred to the centromere.
阿尔法卫星 DNA（AS）是灵长类动物着丝粒的主要 DNA 成分，由大约 170bp 的串联重复单元组成。同源人的 AS（人科；人类和大型猿类）包括组织成更高阶重复（HOR）结构的序列，具有基本重复单元的多个拷贝的周期性出现。在这里，我们在 siamang 的 AS 中鉴定出一个 HOR，siamang 是一种与同源人在进化上不同的小型猿类，但属于人科（灵长目）。我们对大片段基因组 DNA 进行了测序，发现了由六个和四个基本重复单元组成的块的重复。因此，AS 组织成 HOR 是类人猿的特征，而不是目前所假设的同源人。除了着丝粒，siamang 还在末端异染色质块中携带 AS，目前尚不确定这些包含 HOR 的 AS 序列是来自着丝粒还是来自末端异染色质。即使在后一种情况下，这些序列也可能通过转移到着丝粒而影响着丝粒 AS 的组成。
