Instituto de Ciências Biológicas, Universidade Federal do Amazonas, Manaus, Amazonas, Brazil.
J Fish Biol. 2010 Apr;76(5):1117-27. doi: 10.1111/j.1095-8649.2010.02550.x.
Three species of cichlids belonging to the genus Symphysodon have demonstrated interspecific and intraspecific variation in nucleolus organizer regions (NOR) detected with silver nitrate. In order to understand the evolution of this marker in the genus, the structural variability of these sequences in mitotic chromosomes from Symphysodon aequifasciatus, Symphysodon discus and Symphysodon haraldi was investigated using both silver nitrate impregnation and hybridization of the 18S rRNA gene probe. For the three species, the two markers were intraspecifically and interspecifically variable both in the number and in the size of the sites. This polymorphism may stem from duplications and translocations, which suggests that structural chromosome rearrangements effectively act in the karyoevolution of wild Symphysodon species and may have favoured the adaptability of these fishes to diverse aquatic environments in the Amazon.
三种慈鲷鱼，属 Symphysodon 种，已被证明在银染检测核仁组织区（NOR）时具有种间和种内变异。为了了解该标记在属中的进化情况，利用银染和 18S rRNA 基因探针杂交技术，研究了来自 Symphysodon aequifasciatus、Symphysodon discus 和 Symphysodon haraldi 有丝分裂染色体中这些序列的结构变异性。对于这三个物种，这两个标记在数量和大小上都是种内和种间可变的。这种多态性可能源于重复和易位，这表明结构染色体重排有效地作用于野生 Symphysodon 物种的核进化，并可能促进了这些鱼类对亚马逊地区各种水生环境的适应性。
