Department of Genetics, Faculty of Science, Kasetsart University, 50 Paholyothin, Chatuchak, Bangkok 10900, Thailand.
Chromosome Res. 2009;17(8):975-86. doi: 10.1007/s10577-009-9101-7. Epub 2009 Nov 24.
The butterfly lizard (Leiolepis reevesii rubritaeniata) has the diploid chromosome number of 2n = 36, comprising two distinctive components, macrochromosomes and microchromosomes. To clarify the conserved linkage homology between lizard and snake chromosomes and to delineate the process of karyotypic evolution in Squamata, we constructed a cytogenetic map of L. reevesii rubritaeniata with 54 functional genes and compared it with that of the Japanese four-striped rat snake (E. quadrivirgata, 2n = 36). Six pairs of the lizard macrochromosomes were homologous to eight pairs of the snake macrochromosomes. The lizard chromosomes 1, 2, 4, and 6 corresponded to the snake chromosomes 1, 2, 3, and Z, respectively. LRE3p and LRE3q showed the homology with EQU5 and EQU4, respectively, and LRE5p and LRE5q corresponded to EQU7 and EQU6, respectively. These results suggest that the genetic linkages have been highly conserved between the two species and that their karyotypic difference might be caused by the telomere-to-telomere fusion events followed by inactivation of one of two centromeres on the derived dicentric chromosomes in the lineage of L. reevesii rubritaeniata or the centric fission events of the bi-armed macrochromosomes and subsequent centromere repositioning in the lineage of E. quadrivirgata. The homology with L. reevesii rubritaeniata microchromosomes were also identified in the distal regions of EQU1p and 1q, indicating the occurrence of telomere-to-telomere fusions of microchromosomes to the p and q arms of EQU1.
蝴蝶蜥（Leiolepis reevesii rubritaeniata）的二倍体染色体数为 2n = 36，由两个不同的组成部分组成，即大染色体和微染色体。为了阐明蜥蜴和蛇染色体之间保守的连锁同源性，并描绘爬行动物科的核型进化过程，我们构建了蝴蝶蜥（Leiolepis reevesii rubritaeniata）的细胞遗传学图谱，其中包含 54 个功能基因，并将其与日本四线锦蛇（E. quadrivirgata，2n = 36）进行了比较。蜥蜴的 6 对大染色体与蛇的 8 对大染色体同源。蜥蜴染色体 1、2、4 和 6 分别与蛇染色体 1、2、3 和 Z 相对应。LRE3p 和 LRE3q 分别与 EQU5 和 EQU4 具有同源性，而 LRE5p 和 LRE5q 则分别与 EQU7 和 EQU6 相对应。这些结果表明，这两个物种之间的遗传连锁高度保守，它们的核型差异可能是由于在蝴蝶蜥（Leiolepis reevesii rubritaeniata）或四线锦蛇（E. quadrivirgata）的谱系中，两个衍生的二价体染色体的端粒到端粒融合事件以及两个着丝粒之一的失活所导致，或者是在蝴蝶蜥（Leiolepis reevesii rubritaeniata）的谱系中，双着丝粒大染色体的着丝粒分裂和随后的着丝粒重新定位所导致。在 EQU1p 和 1q 的远端也鉴定到与蝴蝶蜥（Leiolepis reevesii rubritaeniata）微染色体的同源性，表明微染色体的端粒到端粒融合发生在 EQU1 的 p 和 q 臂上。
