Evolution in the block: common elements of 5S rDNA organization and evolutionary patterns in distant fish genera
Evolution in the block: common elements of 5S rDNA organization and evolutionary patterns in distant fish genera
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DOI：
10.1139/g11-074
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发表时间：
2012-01-01
期刊：
影响因子：
3.1
通讯作者：
Garcia-Vazquez, Eva
中科院分区：
文献类型：
--
作者：
Campo, Daniel;Garcia-Vazquez, Eva
5S rDNA在基因组中组织为由编码序列加上非转录间隔区（NTS）组成的结构单元的串联重复拷贝。编码区在进化中高度保守，而NTS在长度和序列上都不同。有人提出，5S rRNA基因是通过协同进化而出现的基因家族的成员。在这项研究中，我们描述了5S rDNA的分子组织和进化的属Loporhombus和Scophthalmus（Scophthalmidae），并与已经知道的5S rDNA的非常不同的属Merluccius（Merlucciae）和萨尔莫（鲑亚科），以确定共同的结构元件或模式，了解5S rDNA在鱼类的进化。在所有属的5S rDNA家族内的高种内和种间多样性可以解释的重复，缺失和转座事件的组合。在所有的5S rDNA成员跨物种的序列块具有高度的相似性被确定为四个研究的属，与强烈的非编码区内的基因转换的证据。我们提出了一个模型来解释5S rDNA的进化，其中的进化单位是核苷酸的块，而不是整个序列或单个核苷酸。这种模式意味着一种“双速”进化：基因块内的进化缓慢（通过重组实现同质化），基因家族内的进化快速（通过复制和缺失实现多样化）。
The 5S rDNA is organized in the genome as tandemly repeated copies of a structural unit composed of a coding sequence plus a nontranscribed spacer (NTS). The coding region is highly conserved in the evolution, whereas the NTS vary in both length and sequence. It has been proposed that 5S rRNA genes are members of a gene family that have arisen through concerted evolution. In this study, we describe the molecular organization and evolution of the 5S rDNA in the genera Lepidorhombus and Scophthalmus (Scophthalmidae) and compared it with already known 5S rDNA of the very different genera Merluccius (Merluccidae) and Salmo (Salmoninae), to identify common structural elements or patterns for understanding 5S rDNA evolution in fish. High intra-and interspecific diversity within the 5S rDNA family in all the genera can be explained by a combination of duplications, deletions, and transposition events. Sequence blocks with high similarity in all the 5S rDNA members across species were identified for the four studied genera, with evidences of intense gene conversion within noncoding regions. We propose a model to explain the evolution of the 5S rDNA, in which the evolutionary units are blocks of nucleotides rather than the entire sequences or single nucleotides. This model implies a "two-speed" evolution: slow within blocks (homogenized by recombination) and fast within the gene family (diversified by duplications and deletions).