Centro de Estudos e Células Tronco, Terapia Celular e Genética Toxicológica, Universidade Federal de Mato Grosso do Sul, Campo Grande, Brazil.
Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.
Cytogenet Genome Res. 2024;164(2):110-120. doi: 10.1159/000539476. Epub 2024 May 30.
Rhipidomys is the second most specious and the most widespread genus of the tribe Thomasomyini. Chromosomal data have been an important tool in the taxonomy of the group that presents low variability of diploid number (2n) and highly variable fundamental numbers (FNs). Despite such diversity, the genus has been studied mainly by classical and banding cytogenetic techniques.
This study performed a comparative study between R. emiliae (2n = 44, FN = 52), R. macrurus (2n = 44, FN = 49), R. nitela (2n = 50, FN = 71), and R. mastacalis (2n = 44, FN = 72) using chromosome painting probes of two Oryzomyini species.
Our analysis revealed pericentric inversion as the main rearrangement involved in the karyotype evolution of the group, although tandem fusions/fissions were also detected. In addition, we detected eight syntenic associations exclusive of the genus Rhipidomys, and three syntenic associations shared between species of the tribe Thomasomyini and Oryzomyini.
Comparative cytogenetic analysis by ZOO-FISH on genus Rhipidomys supports a pattern of chromosomal rearrangement already suggested by comparative G-banding. However, the results suggest that karyotype variability in the genus could also involve the occurrence of an evolutionary new centromere.
林跳鼠属是托马斯鼠族中第二大且分布最广的属。染色体数据一直是该群体分类学的重要工具，该群体的二倍体数目（2n）变化较小，而基本染色体数（FN）变化较大。尽管如此，该属主要还是通过经典和带型细胞遗传学技术进行研究。
本研究使用两种稻鼠属物种的染色体涂染探针，对林跳鼠属的 R. emiliae（2n = 44，FN = 52）、R. macrurus（2n = 44，FN = 49）、R. nitela（2n = 50，FN = 71）和 R. mastacalis（2n = 44，FN = 72）进行了比较研究。
我们的分析表明，虽然也检测到串联融合/裂变，但着丝粒周围倒位是该属核型进化中涉及的主要重排。此外，我们还检测到了 8 个仅存在于林跳鼠属的同源染色体组合，以及 3 个存在于托马斯鼠族和稻鼠属物种之间的同源染色体组合。
通过 ZOO-FISH 对林跳鼠属的比较细胞遗传学分析支持了比较 G 带所提出的染色体重排模式。然而，结果表明，该属的染色体多样性也可能涉及新的进化着丝粒的发生。
