Nanda I, Schartl M, Feichtinger W, Epplen J T, Schmid M
Institut für Humangenetik der Universität, Würzburg, Federal Republic of Germany.
Chromosoma. 1992 Mar;101(5-6):301-10. doi: 10.1007/BF00346009.
Animal sex chromosome evolution has started on different occasions with a homologous pair of autosomes leading to morphologically differentiated gonosomes. In contrast to other vertebrate classes, among fishes cytologically demonstrable sex chromosomes are rare. In reptiles, certain motifs of simple tandemly repeated DNA sequences like (gata)n/(gaca)m are associated with the constitutive heterochromatin of sex chromosomes. In this study a panel of simple repetitive sequence probes was hybridized to restriction enzyme digested genomic DNA of poeciliid fishes. Apparent male heterogamety previously established by genetic experiments in Poecilia reticulata (guppy) was correlated with male-specific hybridization using the (GACA)4 probe. The (GATA)4 oligonucleotide identifies certain male guppies by a Y chromosomal polymorphism in the outbred population. In contrast none of the genetically defined heterogametic situations in Xiphophorus could be verified consistently using the collection of simple repetitive sequence probes. Only individuals from particular populations produced sex-specific patterns of hybridization with (GATA)4. Additional poeciliid species (P. sphenops, P. velifera) harbour different sex-specifically organized simple repeat motifs. The observed sex-specific hybridization patterns were substantiated by banding analyses of the karyotypes and by in situ hybridization using the (GACA)4 probe.
动物的性染色体进化在不同情况下始于一对同源常染色体，进而形成形态上有差异的性染色体。与其他脊椎动物类别不同，鱼类中细胞学上可证实的性染色体很少见。在爬行动物中，某些简单串联重复DNA序列基序，如（gata）n/（gaca）m，与性染色体的组成型异染色质相关。在本研究中，一组简单重复序列探针与食蚊鱼科鱼类经限制性内切酶消化的基因组DNA进行杂交。先前通过遗传实验在孔雀鱼（食蚊鱼）中确定的明显雄性异配性，与使用（GACA）4探针的雄性特异性杂交相关。（GATA）4寡核苷酸通过远交群体中的Y染色体多态性识别某些雄性孔雀鱼。相比之下，利用简单重复序列探针组合，剑尾鱼属中任何已确定的遗传异配情况都无法得到一致验证。只有来自特定种群的个体与（GATA）4产生性别特异性杂交模式。其他食蚊鱼科物种（斯氏食蚊鱼、帆鳍食蚊鱼）具有不同的性别特异性组织的简单重复基序。观察到的性别特异性杂交模式通过核型的带型分析以及使用（GACA）4探针的原位杂交得到证实。
