Calado L L, Bertollo L A C, Cioffi M B, Costa G W W F, Jacobina U P, 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 27;13(4):9951-9. doi: 10.4238/2014.November.27.24.
Several chromosomal features of Gerreidae fish have been found to be conserved. In this group, it is unclear whether the high degree of chromosomal stasis is maintained when analyzing more dynamic regions of chromosomes, such as rDNA sites that generally show a higher level of variability. Thus, cytogenetic analyses were performed on 3 Atlantic species of the genus Eucinostomus using conventional banding (C-banding, Ag-NOR), AT- and GC-specific fluorochromes, and fluorescence in situ hybridization mapping of telomeric sequences and 5S and 18S rDNA sites. The results showed that although the karyotypical macrostructure of these species is similar (2n = 48 chromosomes, simple Ag-NORs seemingly located on homeologous chromosomes and centromeric heterochromatin pattern), there are differences in the positions of rDNA subunits 5S and 18S. Thus, the ribosomal sites have demonstrated to be effective cytotaxonomic markers in Eucinostomus, presenting a different evolutionary dynamics in relation to other chromosomal regions and allowing access to important evolutionary changes in this group.
已发现银鲈科鱼类的几个染色体特征是保守的。在这一类群中，当分析染色体更具动态性的区域，如通常显示出较高变异性水平的核糖体DNA（rDNA）位点时，尚不清楚高度的染色体稳定性是否得以维持。因此，利用常规显带技术（C显带、银染核仁组织区）、AT特异性和GC特异性荧光染料以及端粒序列、5S和18S rDNA位点的荧光原位杂交图谱，对真镰鱼属的3个大西洋物种进行了细胞遗传学分析。结果表明，尽管这些物种的核型宏观结构相似（2n = 48条染色体，简单的银染核仁组织区似乎位于同源染色体上，且着丝粒异染色质模式相同），但5S和18S rDNA亚基的位置存在差异。因此，核糖体位点已被证明是真镰鱼属中有效的细胞分类学标记，与其他染色体区域相比呈现出不同的进化动态，并有助于了解该类群的重要进化变化。
