Pazian Marlon F, Shimabukuro-Dias Cristiane Kioko, Pansonato-Alves José Carlos, Oliveira Claudio, Foresti Fausto
Laboratório de Biologia e Genética de Peixes, Departamento de Morfologia, Instituto de Biociências, Universidade Estadual Paulista, Distrito de Rubião Junior S/N, Rubião Júnior, Botucatu, SP, Brazil.
Genetica. 2013 Mar;141(1-3):1-9. doi: 10.1007/s10709-013-9701-1. Epub 2013 Jan 24.
Some species of the genus Characidium have heteromorphic ZZ/ZW sex chromosomes with a totally heterochromatic W chromosome. Methods for chromosome microdissection associated with chromosome painting have become important tools for cytogenetic studies in Neotropical fish. In Characidium cf. fasciatum, the Z chromosome contains a pericentromeric heterochromatin block, whereas the W chromosome is completely heterochromatic. Therefore, a probe was produced from the W chromosome through microdissection and degenerate oligonucleotide-primed polymerase chain reaction amplification. FISH was performed using the W probe on the chromosomes of specimens of this species. This revealed expressive marks in the pericentromeric region of the Z chromosome as well as a completely painted W chromosome. When applying the same probe on chromosome preparations of C. cf. gomesi and Characidium sp., a pattern similar to C. cf. fasciatum was found, while C. cf. zebra, C. cf. lagosantense and Crenuchus spilurus species showed no hybridization signals. Structural changes in the chromosomes of an ancestral sexual system in the group that includes the species C. cf. gomesi, C. cf. fasciatum and Characidium sp., could have contributed to the process of speciation and could represent a causal mechanism of chromosomal diversification in this group. The heterochromatinization process possibly began in homomorphic and homologous chromosomes of an ancestral form, and this process could have given rise to the current patterns found in the species with sex chromosome heteromorphism.
丽脂鲤属的一些物种具有异形的ZZ/ZW性染色体，其中W染色体完全异染色质化。与染色体涂染相关的染色体显微切割方法已成为新热带鱼细胞遗传学研究的重要工具。在似带纹丽脂鲤中，Z染色体含有一个着丝粒周围异染色质块，而W染色体完全异染色质化。因此，通过显微切割和简并寡核苷酸引物聚合酶链反应扩增从W染色体产生了一个探针。使用该W探针对该物种标本的染色体进行荧光原位杂交（FISH）。这揭示了Z染色体着丝粒周围区域有明显标记以及W染色体完全被涂染。当将相同探针应用于似戈氏丽脂鲤和丽脂鲤属某物种的染色体标本时，发现了与似带纹丽脂鲤相似的模式，而似斑马丽脂鲤、似拉戈桑滕斯丽脂鲤和斯氏溪脂鲤物种未显示杂交信号。在包括似戈氏丽脂鲤、似带纹丽脂鲤和丽脂鲤属某物种的类群中，祖先性系统染色体的结构变化可能对物种形成过程有贡献，并且可能代表该类群染色体多样化的因果机制。异染色质化过程可能始于祖先形式的同形和同源染色体，并且这个过程可能导致了在具有性染色体异形的物种中发现的当前模式。
