Haaf T, Ward D C
Department of Genetics, Yale University School of Medicine, New Haven, CT 06510, USA.
Cytogenet Cell Genet. 1995;70(3-4):258-62. doi: 10.1159/000134047.
The chromosomes of the tree shrew Tupaia belangeri exhibit highly localized CENP-B box sequences in the centromeric regions of most chromosomes. Telomeric sequences are present at the ends of all chromosomes and, in addition, at specific interstitial chromosomal sites that likely represent remnants of ancestral telomeres. This suggests that Robertsonian and tandem chromosome fusion events have occurred in the karyotypic evolution of Tupaiidae. In Tupaia skin fibroblasts CENP-B boxes are almost always clustered together at one pole of the interphase nucleus, whereas the telomeric domains are relatively evenly distributed throughout the whole nuclear volume. The observed orientation of the centromeres is reminiscent of the Rabl polarization of chromosomes; this is the first mammalian cell substrate in which such an higher-order chromosomal organization has been observed. CENP-B box sequences are found in several other mammalian species. The implications for recent parallel evolution of CENP-B binding motifs and concerted evolution of these sequences are discussed.
树鼩（Tupaia belangeri）的染色体在大多数染色体的着丝粒区域呈现高度局部化的CENP - B框序列。端粒序列存在于所有染色体的末端，此外，还存在于特定的染色体间质位点，这些位点可能代表祖先端粒的残余。这表明在树鼩科的核型进化中发生了罗伯逊易位和串联染色体融合事件。在树鼩皮肤成纤维细胞中，CENP - B框几乎总是聚集在间期细胞核的一极，而端粒结构域则相对均匀地分布在整个核体积中。观察到的着丝粒方向让人联想到染色体的拉布尔极化；这是首次在哺乳动物细胞底物中观察到这种高阶染色体组织。在其他几种哺乳动物物种中也发现了CENP - B框序列。文中讨论了CENP - B结合基序近期平行进化以及这些序列协同进化的意义。
