Takagui Fábio Hiroshi, Dias Ana Lucia, Birindelli José Luís Olivan, Swarça Ana Claudia, da Rosa Renata, Lui Roberto Laridondo, Fenocchio Alberto Sergio, Giuliano-Caetano Lucia
Laboratory of Animal Cytogenetics; Department of General Biology, CCB, Universidade Estadual de Londrina. Rodovia Celso Garcia Cid, PR 445, km 380, Londrina-Brasil.
Museum of Zoology, Department of Animal and Plant Biology, CCB, Universidade Estadual de Londrina. Rodovia Celso Garcia Cid, PR 445, km 380, Londrina-Brasil.
Comp Cytogenet. 2017 Jan 9;11(1):55-64. doi: 10.3897/CompCytogen.v11i1.10496. eCollection 2017.
The family Doradidae (Siluriformes) is an important group of fishes endemic to freshwater ecosystems in South America. Some cytogenetic studies have been conducted focused on the group; however, there are no reports on the occurrence of B chromosomes for the family. In this paper the chromosomal characteristics of (Valenciennes, 1840), (Valenciennes, 1821) and (Kner, 1855) were investigated through classical cytogenetics approaches. The conventional staining reveals 2n=58 in and , however with distinct karyotypic formulae, possibly originated by pericentric inversions. In a derivate karyotype was described with 2n=66 and predominance of acrocentric chromosomes. The C banding pattern was resolutive in discriminating the three species, being considered an important cytotaxonomic marker. All species showed B chromosomes totally heterochromatic with non-Mendelian segregation during meiosis and low frequencies in mitotic cells. The probably origin of these additional elements was through fragmentations of chromosomes of the standard complement, which occurred recently and independently in these three species. The diploid number observed in is an evidence of centric fusions and up to the moment it is the highest diploid number reported for Doradidae.
陶乐鲶科（鲇形目）是南美洲淡水生态系统特有的一类重要鱼类。已经针对该类群开展了一些细胞遗传学研究；然而，尚无关于该科B染色体存在情况的报道。在本文中，通过经典细胞遗传学方法对陶乐鲶（瓦伦西恩斯，1840年）、斑陶乐鲶（瓦伦西恩斯，1821年）和安芬陶乐鲶（克纳，1855年）的染色体特征进行了研究。常规染色显示陶乐鲶和斑陶乐鲶的2n = 58，但其核型公式不同，可能源于臂间倒位。在安芬陶乐鲶中描述了一种衍生核型，其2n = 66，且近端着丝粒染色体占优势。C带模式在区分这三个物种方面具有决定性作用，被认为是一个重要的细胞分类学标记。所有物种均显示出B染色体完全异染色质化，在减数分裂过程中呈现非孟德尔分离，在有丝分裂细胞中的频率较低。这些额外染色体的可能起源是标准染色体组的染色体片段化，这种情况最近在这三个物种中独立发生。在安芬陶乐鲶中观察到的二倍体数目是着丝粒融合的一个证据，并且截至目前它是陶乐鲶科报道的最高二倍体数目。
