Molecular organization of 5S rDNA in bitterlings (Cyprinidae)
Molecular organization of 5S rDNA in bitterlings (Cyprinidae)
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DOI：
10.1007/s10709-008-9294-2
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发表时间：
2009-04-01
期刊：
影响因子：
1.5
通讯作者：
Kubota, Souichirou
中科院分区：
文献类型：
--
作者：
Fujiwara, Mika;Inafuku, Junya;Kubota, Souichirou
为了解5S rDNA阵列的进化特征，对4个属10个种/亚种的淡水鱼5S rRNA基因和NTS序列进行了研究。Southern杂交分析表明，所有受检苦味鱼都有5S rDNA串联重复序列的总体趋势。序列分析表明，在所研究的10个种/亚种中，有6个种/亚种的5S rRNA基因有一个保守的120个核苷酸序列和一个56-67个核苷酸的短核苷酸序列，其中包括两个不同的部分：保守的(5‘-侧翼部分；位于-1至-38位)和可变部分(3’-侧翼部分)。保守的NTS区很可能是迄今为止在各种脊椎动物中观察到的外部启动子，而可变的NTS区由于其核苷酸多态性可以分为两种类型。利用5S rRNA基因和NTS序列进行的分子系统发育分析表明，在物种形成之前，5S rDNA发生了复制，基因和保守的NTS区发生了协同进化，但维持NTS区的可变区是一个出生和死亡的过程。因此，受检苦鱼中的5S rDNA可能是在一种混合进化过程中进化的。
Molecular organization and nucleotide sequences of the 5S rRNA gene and NTS were investigated in freshwater fish, bitterlings (Acheilognathinae), including 10 species/subspecies of four genera, Acheilognathus, Pseudoperilampus, Rhodeus, and Tanakia, to understand the evolutionary trait of 5S rDNA arrays. Southern hybridization analysis revealed a general trend with tandem repeats of 5S rDNA in all the examined bitterlings. Sequence analysis demonstrated a conserved 120 bp sequence of the 5S rRNA gene and a short NTS of 56-67 bp with two distinct portions, a conserved (5'-flanking portion; at positions -1 to -38) and a variable part (3'-flanking portion), in 6 of 10 species/subspecies examined. The conserved NTS region was most likely an external promoter so far observed in various vertebrates, whereas the variable NTS region could be divided into two types due to its nucleotide polymorphisms. Molecular phylogeny using the 5S rRNA gene and NTS sequences suggested the occurrence of 5S rDNA duplication before speciation and a concerted evolution for the gene and conserved NTS regions, but a birth-and-death process to maintain the variable NTS region. Thus, the 5S rDNA in the examined bitterlings might have evolved under a mixed process of evolution.