Dos Santos Paixão Vergiana, Malcher Stella Miranda, Oliveira da Silva Willam, Ferguson-Smith Malcolm Andrew, O'Brien Patricia Caroline Mary, Rossi Rogério Vieira, Pieczarka Julio Cesar, Nagamachi Cleusa Yoshiko
Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará (UFPA), Pará, Brazil.
Department of Veterinary Medicine, Cambridge Resource Centre for Comparative Genomics, University of Cambridge, Cambridge, UK.
Sci Rep. 2025 Feb 19;15(1):6111. doi: 10.1038/s41598-025-89517-9.
Oecomys (Rodentia, Sigmodontinae, Oryzomyini) is a taxonomically complex and cytogenetically diverse genus with a controversial intraspecific phylogenetic relationship. Karyotypic analyses, using whole chromosome probes from Hylaeamys megacephalus (HME, Sigmodontinae, Oryzomyini) in some taxonomic lineages of this genus have detected the rearrangements that shaped their karyotypes, in addition to revealing relevant insights into the taxonomic status of these taxa. Thus, to investigate the chromosomal evolution of the genus, we characterized the karyotype of Oecomys rutilus (ORU) with HME probes, establishing chromosomal homology maps with the karyotypes of other congeners. The chromosomal phylogeny obtained by Maximum Parsimony analysis recovered the genus Oecomys as monophyletic, with moderate bootstrap support (68%). This clade branches into two large groups, the first including O. rutilus followed by O. catherinae-Rio de Janeiro and O. catherinae-Pará; the other group includes O. auyantepui followed by O. paricola cytotype C and O. paricola cytotype A + cytotype B. We detected that these taxa underwent intensive reorganization of their karyotypes, the rearrangements producing this diversity were 15 pericentric inversions, 12 centric fusions, 11 fissions, 5 in tandem fusions, 8 translocations and the addition/deletion of constitutive heterochromatin on two autosomes and the X chromosomes. However, despite the high number of chromosomal rearrangements found, we identified some entirely conserved syntenic blocks shared among all species analyzed. From these data, we hypothesized a putative ancestral karyotype. We also detected exclusive characteristics for ORU, the syntenic blocks HME 1/20/4 (ORU 1), HME (16,17)/3 (ORU 2), HME 2/1 (ORU 4), HME 2/7 (ORU 5), HME 5/(9,10)/8 (ORU 3), HME 19/12 (ORU 9). We provide an overview of the chromosomal reorganization of the genus that points to a high chromosomal diversity and show that chromosomal rearrangements play an important role in the radiation of these species.
奥氏鼠属（啮齿目，稻鼠亚科，稻鼠族）是一个分类复杂且细胞遗传学上具有多样性的属，其种内系统发育关系存在争议。在该属的一些分类谱系中，使用来自巨头稻鼠（HME，稻鼠亚科，稻鼠族）的全染色体探针进行核型分析，除了揭示这些分类单元的分类地位的相关见解外，还检测到了塑造其核型的重排。因此，为了研究该属的染色体进化，我们用HME探针表征了红腹奥氏鼠（ORU）的核型，建立了与其他同属物种核型的染色体同源图谱。通过最大简约分析获得的染色体系统发育结果显示奥氏鼠属为单系类群，有中等程度的自展支持率（68%）。这个分支分为两个大组，第一组包括红腹奥氏鼠，接着是里约热内卢卡氏奥氏鼠和帕拉卡氏奥氏鼠；另一组包括奥扬特普伊奥氏鼠，接着是细胞型C的帕里科拉奥氏鼠和细胞型A + 细胞型B的帕里科拉奥氏鼠。我们检测到这些分类单元经历了核型的强烈重组，产生这种多样性的重排包括15次臂间倒位、12次着丝粒融合、11次断裂、5次串联融合、8次易位以及两条常染色体和X染色体上组成型异染色质的增减。然而，尽管发现了大量的染色体重排，我们在所有分析的物种中鉴定出了一些完全保守的同线基因座。根据这些数据，我们推测了一个假定的祖先核型。我们还检测到了红腹奥氏鼠的独特特征，即同线基因座HME 1/20/4（ORU 1）、HME (16,17)/3（ORU 2）、HME 2/1（ORU 4）、HME 2/7（ORU 5）、HME 5/(9,10)/8（ORU 3）、HME 19/12（ORU 9）。我们概述了该属的染色体重组情况，表明其具有高度的染色体多样性，并表明染色体重排在这些物种的辐射中起重要作用。
