Santos Alan Gomes Dos, Souza José Francisco de Sousa E, Soares Simone Cardoso, Nakayama Celeste Mutuko, Feldberg Eliana
Instituto Nacional de Pesquisas da Amazônia (INPA), Programa de Pós-graduação em Genética, Conservação e Biologia Evolutiva, Laboratório de Genética Animal, Manaus, AM, Brazil.
Instituto Nacional de Pesquisas da Amazônia (INPA), Coordenação de Biodiversidade, Laboratório de Genética Animal, Manaus, AM, Brazil.
Genet Mol Biol. 2023 Nov 10;46(4):e20230088. doi: 10.1590/1678-4685-GMB-2023-0088. eCollection 2023.
The tribe Serrasalmini is a diverse group with paraphyletic genera and taxonomic uncertainties. Several studies have been carried out in this group of fish in order to understand this problem, including the cytogenetic approach. In this study, three species of a clade of Serrasalmini were characterized cytogenetically - Pristobrycon striolatus, Catoprion absconditus and Pygopristis denticulatus. The three species presented diploid number (2n) equal to 62 chromosomes, of one and two arms, with karyotypic formulas and species-specific fundamental numbers. Heterochromatin is centromeric and terminal (bi-telomeric) in most chromosomes, with a conspicuous interstitial block at pair 1 (m) in all three species. The nucleolar organizer regions were multiple and C-band positive, and their location was confirmed via 18S ribosomal DNA mapping; however, with additional sites. The 5S rDNA was located in interstitial region of long arm of pair 1 (m), in the three species (homeologous). Moreover, we observed synteny between 18S and 5S in the species C. absconditus and P. denticulatus, which, according to fiber-FISH, are interspersed. Thus, the maintenance of 2n (62) evidences the diversification of chromosomal formulas within the clade by non-Robertsonian rearrangements and reflects the paraphyly of the related species.
锯脂鲤族是一个多样化的群体，包含并系属且分类存在不确定性。为了解决这个问题，已对该类群鱼类开展了多项研究，包括细胞遗传学方法。在本研究中，对锯脂鲤族一个分支的三个物种进行了细胞遗传学特征分析——细纹原锯脂鲤、隐匿锯脂鲤和细齿锯脂鲤。这三个物种的二倍体数（2n）均为62条染色体，包括单臂和双臂染色体，具有核型公式和物种特异性基本数。在大多数染色体中，异染色质位于着丝粒和末端（双端粒），在所有三个物种的第1对（中着丝粒）染色体上有明显的中间带。核仁组织区是多个且C带阳性，其位置通过18S核糖体DNA定位得以确认；然而，存在额外位点。5S rDNA位于所有三个物种第1对（中着丝粒）染色体长臂的中间区域（同源）。此外，我们在隐匿锯脂鲤和细齿锯脂鲤中观察到18S和5S之间的同线性，根据纤维荧光原位杂交，它们是穿插排列的。因此，2n（62）的维持证明了该分支内染色体公式通过非罗伯逊重排的多样化，并反映了相关物种的并系性。
