Koga Akihiko, Hirai Yuriko, Terada Shoko, Jahan Israt, Baicharoen Sudarath, Arsaithamkul Visit, Hirai Hirohisa
Primate Research Institute, Kyoto University, Inuyama City 484-8506, Japan
Primate Research Institute, Kyoto University, Inuyama City 484-8506, Japan.
DNA Res. 2014 Aug;21(4):407-15. doi: 10.1093/dnares/dsu005. Epub 2014 Feb 27.
Alpha-satellite DNA (AS) is a main DNA component of primate centromeres, consisting of tandemly repeated units of ~170 bp. The AS of humans contains sequences organized into higher-order repeat (HOR) structures, in which a block of multiple repeat units forms a larger repeat unit and the larger units are repeated tandemly. The presence of HOR in AS is widely thought to be unique to hominids (family Hominidae; humans and great apes). Recently, we have identified an HOR-containing AS in the siamang, which is a small ape species belonging to the genus Symphalangus in the family Hylobatidae. This result supports the view that HOR in AS is an attribute of hominoids (superfamily Hominoidea) rather than hominids. A single example is, however, not sufficient for discussion of the evolutionary origin of HOR-containing AS. In the present study, we developed an efficient method for detecting signs of large-scale HOR and demonstrated HOR of AS in all the three other genera. Thus, AS organized into HOR occurs widely in hominoids. Our results indicate that (i) HOR-containing AS was present in the last common ancestor of hominoids or (ii) HOR-containing AS emerged independently in most or all basal branches of hominoids. We have also confirmed HOR occurrence in centromeric AS in the Hylobatidae family, which remained unclear in our previous study because of the existence of AS in subtelomeric regions, in addition to centromeres, of siamang chromosomes.
α卫星DNA（AS）是灵长类动物着丝粒的主要DNA成分，由约170 bp的串联重复单元组成。人类的AS包含组织成高阶重复（HOR）结构的序列，其中多个重复单元组成一个更大的重复单元，这些更大的单元串联重复。人们普遍认为AS中HOR的存在是类人猿（人科；人类和大猩猩）所特有的。最近，我们在合趾猿中鉴定出了一种含有HOR的AS，合趾猿是长臂猿科合趾猿属的一种小型猿类。这一结果支持了AS中的HOR是类人猿（人猿总科）而非人科动物的特征这一观点。然而，仅一个例子不足以讨论含HOR的AS的进化起源。在本研究中，我们开发了一种检测大规模HOR迹象的有效方法，并在其他三个属中都证实了AS的HOR。因此，组织成HOR的AS在类人猿中广泛存在。我们的结果表明：（i）含HOR的AS存在于类人猿的最后一个共同祖先中；或者（ii）含HOR的AS在类人猿的大多数或所有基部支系中独立出现。我们还证实了长臂猿科着丝粒AS中存在HOR，在我们之前的研究中，由于合趾猿染色体着丝粒以外的亚端粒区域也存在AS，这一点尚不清楚。
