Kowalski Samantha, Haerter Chrystian Aparecido Grillo, Perin Diana Paula, Takagui Fábio Hiroshi, Viana Patrik Ferreira, Feldberg Eliana, Blanco Daniel Rodrigues, Traldi Josiane Baccarin, Giuliano-Caetano Lucia, Lui Roberto Laridondo
Universidade Estadual de Londrina, Centro de Ciências Biológicas, Londrina, PR, Brazil.
Universidade Estadual do Oeste do Paraná, Centro de Ciências Biológicas e da Saúde, Cascavel, PR, Brazil.
Genet Mol Biol. 2024 Mar 25;47(1):e20230105. doi: 10.1590/1678-4685-GMB-2023-0105. eCollection 2024.
Centromochlinae is a widely diverse subfamily with more than 50 species and several taxonomic conflicts due to morphological similarity between Tatia and Centromochlus species. However, cytogenetic studies on this group have been limited to only four species so far. Therefore, here we present the karyotype of Centromochlus schultzi from the Xingu River in Brazil using classic cytogenetic techniques, physical mapping of the 5S and 18S rDNAs, and telomeric sequences (TTAGGG)n. The species had 58 chromosomes, simple NORs and 18S rDNA sites. Heterochromatic regions were detected on the terminal position of most chromosomes, including pericentromeric and centromeric blocks that correspond to interstitial telomeric sites. The 5S rDNA had multiple sites, including a synteny with the 18S rDNA in the pair 24st, which is an ancestral feature for Doradidae, sister group of Auchenipteridae, but appears to be a homoplastic trait in this species. So far, C. schultzi is only the second species within Centromochlus to be karyotyped, but it has already presented characteristics with great potential to assist in future discussions on taxonomic issues in the subfamily Centromochlinae, including the first synteny between rDNAs in Auchenipteridae and also the presence of heterochromatic ITSs that could represent remnants of ancient chromosomal fusions.
半鲶亚科是一个种类繁多的亚科，有50多个物种，并且由于塔氏鲶属（Tatia）和半鲶属（Centromochlus）物种之间形态相似而存在一些分类学上的争议。然而，迄今为止，对该类群的细胞遗传学研究仅限于4个物种。因此，我们在这里使用经典细胞遗传学技术、5S和18S rDNA的物理图谱以及端粒序列（TTAGGG）n，展示了来自巴西欣古河的舒氏半鲶（Centromochlus schultzi）的核型。该物种有58条染色体，简单的核仁组织区（NORs）和18S rDNA位点。在大多数染色体的末端位置检测到异染色质区域，包括对应于间粒端粒位点的着丝粒周围和着丝粒区。5S rDNA有多个位点，包括在第24对染色体上与核仁组织区（NOR）的18S rDNA存在同线性，这是奥氏鲶科（Auchenipteridae）姐妹群多须鲶科（Doradidae）的一个祖先特征，但在该物种中似乎是一个同源性状。到目前为止，舒氏半鲶只是半鲶属中第二个进行核型分析的物种，但它已经呈现出具有巨大潜力的特征，有助于未来对半鲶亚科分类学问题的讨论，包括奥氏鲶科中rDNA之间的首次同线性，以及可能代表古代染色体融合残余的异染色质内转录间隔区（ITSs）的存在。
