Jacobina U P, Bertollo L A C, Bello Cioffi M, Molina W F
Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN, Brasil.
Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brasil.
Genet Mol Res. 2014 Nov 14;13(4):9628-35. doi: 10.4238/2014.November.14.7.
In Carangidae, Caranx is taxonomically controversial because of slight morphological differences among species, as well as because of its relationship with the genus Carangoides. Cytogenetic data has contributed to taxonomic and phylogenetic classification for some groups of fish. In this study, we examined the chromosomes of Caranx latus, Caranx lugubris, and Carangoides bartholomaei using classical methods, including conventional staining, C-banding, silver staining for nuclear organizer regions, base-specific fluorochrome, and 18S and 5S ribosomal sequence mapping using in situ hybridization. These 3 species showed chromosome numbers of 2n = 48, simple nuclear organizer regions (pair 1), and mainly centromeric heterochomatin. However, C. latus (NF = 50) and C. bartholomaei (NF = 50) showed a structurally conserved karyotype compared with C. lugubris (NF = 54), with a larger number of 2-armed chromosomes. The richness of GC-positive heterochromatic segments and sites in 5S rDNA in specific locations compared to the other 2 species reinforce the higher evolutionary dynamism in C. lugubris. Cytogenetic aspects shared between C. latus and C. bartholomaei confirm the remarkable phylogenetic proximity between these genera.
在鲹科中，由于物种间细微的形态差异以及它与若鲹属的关系，鲹属在分类学上存在争议。细胞遗传学数据有助于对某些鱼类群体进行分类学和系统发育分类。在本研究中，我们使用经典方法，包括常规染色、C带、核仁组织区银染、碱基特异性荧光染色以及原位杂交进行18S和5S核糖体序列定位，对宽体鲹、黑背鲹和巴氏若鲹的染色体进行了研究。这3个物种的染色体数目均为2n = 48，具有简单的核仁组织区（第1对），且主要为着丝粒异染色质。然而，与黑背鲹（NF = 54）相比，宽体鲹（NF = 50）和巴氏若鲹（NF = 50）显示出结构保守的核型，其二臂染色体数量更多。与其他两个物种相比，特定位置5S rDNA中GC阳性异染色质片段和位点的丰富性增强了黑背鲹更高的进化活力。宽体鲹和巴氏若鲹之间共有的细胞遗传学特征证实了这两个属之间显著的系统发育亲缘关系。
