Nash W G, Wienberg J, Ferguson-Smith M A, Menninger J C, O'Brien S J
H&W Cytogenetic Services, Inc., Lovettsville, VA, USA.
Cytogenet Cell Genet. 1998;83(3-4):182-92. doi: 10.1159/000015176.
The Ursidae family includes eight species, the karyotype of which diverges somewhat, in both chromosome number and morphology, from that of other families in the order Carnivora. The combination of consensus molecular phylogeny and high-resolution trypsin G-banded karyotype analysis has suggested that ancestral chromosomal fissions and at least two fusion events are associated with the development of the different ursid species. Here, we revisit this hypothesis by hybridizing reciprocal chromosome painting probes derived from the giant panda (Ailuropoda melanoleuca), domestic cat (Felis catus), and man (Homo sapiens) to representative bear species karyotypes. Comparative analysis of the different chromosome segment homologies allowed reconstruction of the genomic composition of a putative ancestral bear karyotype based upon the recognition of 39 chromosome segments defined by painting as the smallest conserved evolutionary unit segments (pSCEUS) among these species. The different pSCEUS combinations occurring among modern bear species support and extend the postulated sequence of chromosomal rearrangements and provide a framework to propose patterns of genome reorganization among carnivores and other mammal radiations.
熊科包括八个物种，其核型在染色体数目和形态上与食肉目其他科的核型有所不同。基于分子系统发育共识和高分辨率胰蛋白酶G带核型分析表明，祖先染色体的断裂以及至少两次融合事件与不同熊科物种的进化有关。在这里，我们通过将源自大熊猫（Ailuropoda melanoleuca）、家猫（Felis catus）和人类（Homo sapiens）的相互染色体涂染探针与代表性熊种的核型进行杂交，重新审视这一假说。通过对不同染色体片段同源性的比较分析，基于将涂染定义为这些物种中最小保守进化单位片段（pSCEUS）的39个染色体片段的识别，重建了假定的祖先熊核型的基因组组成。现代熊种中出现的不同pSCEUS组合支持并扩展了假定的染色体重排序列，并为提出食肉动物和其他哺乳动物辐射中的基因组重组模式提供了框架。
