Chromosomal Variability among Allopatric Populations of Erythrinidae Fish Hoplias malabaricus: Mapping of Three Classes of Repetitive DNAs
Chromosomal Variability among Allopatric Populations of Erythrinidae Fish Hoplias malabaricus: Mapping of Three Classes of Repetitive DNAs
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DOI：
10.1159/000227838
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发表时间：
2009-01-01
影响因子：
1.7
通讯作者：
Bertollo, L. A. C.
中科院分区：
文献类型：
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作者：
Cioffi, M. B.;Martins, C.;Bertollo, L. A. C.
采用不同的染色技术（C-、Ag-和CMA(3)带）和荧光原位杂交（FISH）检测18S rDNA、5S rDNA和5SHindIII卫星DNA位点，研究了细胞遗传学上研究最多的红蝇科分类单元——马氏红蝇（Hoplias malabaricus） 3个异源居群的核型和染色体特征。同时，我们还首次从螺旋藻基因组中分离、克隆和鉴定了18S rDNA探针，以期开发出特异性更高的探针。PR、CR和DR 3个种群核型相同，染色体总数为2n = 42条，分别为11 m对和10 sm对，没有异型性染色体，这表明该种群属于a型核。在所有种群中，c阳性异染色质位于染色体的着丝粒区/近着丝粒区，在几对染色体的端粒区也有c阳性异染色质。第16对长臂上的近端异色区是核型中唯一富含gc的片段。5SHindIII卫星DNA总是定位在几个染色体的着丝粒区。18S rDNA位点位于端粒区或着丝粒区，而5S rDNA则位于间隙区或近端区。这3个群体共有几条携带这些重复DNA序列的染色体，以及一些独特的染色体标记。从这个意义上说，种群CR是分化程度最高的，包括18S和5S rDNA探针的合成条件，双FISH证实了这一点。因此，尽管它们包含在相同的主要核型群中，但不同的种群不能被认为是一个绝对的进化单位，正如它们内部染色体分化所证明的那样。版权所有(C) 2009 S. Karger AG，巴塞尔
Karyotype and chromosomal characteristics from 3 allopatric populations of Hoplias malabaricus, cytogenetically the most studied Erythrinidae taxon, were investigated using different staining techniques (C-, Ag-, and CMA(3) banding) as well as fluorescent in situ hybridization (FISH) to detect 18S rDNA, 5S rDNA, and 5SHindIII satellite DNA sites. The isolation, cloning and characterization of an 18S rDNA probe from H. malabaricus genome were also performed for the first time in order to develop a more specific probe. The 3 populations, named PR, CR, and DR, showed identical karyotypes, with 2n = 42 chromosomes composed of 11 m pairs and 10 sm pairs, without heteromorphic sex chromosomes, which characterize the populations as belonging to karyomorph A. In all populations C-positive heterochromatin was situated in the centromeric/pericentromeric regions of the chromosomes, as well as in the telomeric region of several pairs. A conspicuous proximal heterochromatic block on the long arm of pair No. 16 was the only GC-rich segment in the karyotypes. 5SHindIII satellite DNA was always mapped in the centromeric region of several chromosomes. The 18S rDNA sites were situated on the telomeric or centromeric regions, whereas the 5S rDNA showed an interstitial or proximal location in some pairs. Several chromosomes bearing these repetitive DNA sequences were shared by the 3 populations, alongside with some exclusive chromosomal markers. In this sense, population CR was the most differentiated one, including a syntenic condition for the 18S and 5S rDNA probes, as confirmed by double FISH. Thus, despite their inclusion in the same major karyotypic group, the distinct populations cannot be considered an absolute evolutionary unit, as evidenced by their inner chromosomal differentiations. Copyright (C) 2009 S. Karger AG, Basel