Cereali S S, Pomini E, Rosa R, Zawadzki C H, Froehlich O, Giuliano-Caetano L
Departamento de Biologia, Universidade Federal de Mato Grosso do Sul, CCBS, Campo Grande, MS, Brasil.
Genet Mol Res. 2008 Jul 1;7(3):583-91. doi: 10.4238/vol7-3gmr404.
Hypostomus sp 3-Córrego Salobrinha NUP 4247 and Hypostomus sp 2-Rio Perdido NUP 4249, collected in the Planalto da Bodoquena, Paraguay River basin, Brazil, were characterized cytogenetically. Hypostomus sp 3-Córrego Salobrinha showed two modal numbers. This polymorphism consists of the presence of two extrachromosomes. It was not possible to define the diploid number in four specimens, where cell lineages had 2n = 83 and 2n = 84 chromosomes in one individual, and 2n = 82, 2n = 83 and 2n = 84 chromosomes in the others. These results reveal the existence of a genetic mosaic due to the occurrence of one or two extrachromosomes in this species. Hypostomus sp 2-Rio Perdido NUP 4249 showed a 2n = 84, FN = 106 with size heteromorphism in one pair of chromosomes stained with AgNO3. In both species, C banding showed a pattern of heterochromatin distribution with a few small bands in the centromeric and pericentromeric regions coinciding with chromomycin A3 staining. Until now, the major diploid number for the genus Hypostomus was 2n = 80, but the species studied here had chromosomes that in creased this number and the variation for this genus. Our results are also the first cytogenetic data on Hypostomus from the Paraguay River basin.
对采集于巴西巴拉圭河流域博多克内纳高原的Hypostomus sp 3 - 科雷戈萨洛布林哈（NUP 4247）和Hypostomus sp 2 - 里约佩迪多（NUP 4249）进行了细胞遗传学特征分析。Hypostomus sp 3 - 科雷戈萨洛布林哈显示出两个众数染色体数目。这种多态性表现为存在两条额外染色体。在四个样本中无法确定二倍体数目，其中一个个体的细胞系有2n = 83和2n = 84条染色体，其他个体的细胞系有2n = 82、2n = 83和2n = 84条染色体。这些结果揭示了由于该物种中出现一条或两条额外染色体而存在遗传嵌合体。Hypostomus sp 2 - 里约佩迪多NUP 4249显示2n = 84，FN = 106，在用硝酸银染色的一对染色体中存在大小异质性。在这两个物种中，C带显示了异染色质分布模式，着丝粒和着丝粒周围区域有一些小带，与嗜铬霉素A3染色一致。到目前为止，Hypostomus属的主要二倍体数目为2n = 80，但这里研究的物种染色体增加了这个数目以及该属的变异。我们的结果也是巴拉圭河流域Hypostomus的首批细胞遗传学数据。
