Comparative Cytogenetic Analysis of the Genus Symphysodon (Discus Fishes, Cichlidae): Chromosomal Characteristics of Retrotransposons and Minor Ribosomal DNA
Comparative Cytogenetic Analysis of the Genus Symphysodon (Discus Fishes, Cichlidae): Chromosomal Characteristics of Retrotransposons and Minor Ribosomal DNA
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DOI：
10.1159/000279443
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发表时间：
2009-01-01
影响因子：
1.7
通讯作者：
Feldberg, E.
中科院分区：
文献类型：
--
作者：
Gross, M. C.;Schneider, C. H.;Feldberg, E.
作为野生Discus鱼类遗传筛选计划的一部分，我们在有丝分裂和减数分裂染色体上用Rex3反转录转座子和5S rDNA探针进行了C-显带和荧光原位杂交(FISH)，分析了三种鱼类的核型和细胞遗传学特征。3个种的二倍体染色体数目为2n=60，核型以中-亚中部着丝粒染色体为主。C-显带显示主要位于着丝粒周区的结构异染色质块。重复的5S rDNA序列和Rex3反转录转座子在有丝分裂和减数分裂染色体上的物理定位显示，构成异染色质和重复元件部分共存。重复元素的积累、异染色质化和染色体重排之间的关系被假设为解释了粘鱼属的核型分化。需要进一步研究重复元件在适应高度多样化的生境以及在野生铁饼种群中发现的表型和遗传变异性的产生中的作用。版权所有(C)2010 S.Karger AG，巴塞尔
As part of a genetic screening program for wild Discus fishes, we analyzed karyotypes and cytogenetic characteristics of Symphysodon aequifasciatus, S. discus and S. haraldi using C-banding and fluorescent in situ hybridization ( FISH) with the Rex3 retrotransposon and 5S rDNA probes in mitotic and meiotic chromosomes. In the 3 species, diploid chromosome number was 2n = 60 and karyotypes contained predominantly meta-submetacentric chromosomes. C-banding showed blocks of constitutive heterochromatin mainly in the pericentromeric region. Physical mapping of repetitive 5S rDNA sequences and Rex3 retrotransposons in mitotic and meiotic chromosomes showed partial colocalization of constitutive heterochromatin and repetitive elements. Correlations among the accumulation of repetitive elements, heterochromatinization and chromosome rearrangements have been hypothesized to explain the karyo-type differentiation in the Symphysodon genus. The role of repetitive elements in adaptation to highly diverse habitats, as well as in the generation of the phenotypic and genetic variability found in wild Discus populations, needs to be further investigated. Copyright (C) 2010 S. Karger AG, Basel