Long duplication of 18S ribosomal DNA in Cynoglossus lineolatus（Pleuronectiformes： Cynoglossidae）： novel molecular evidencefor unequal crossing over model

Although 188 rDNA sequence is extremely conservative, the polymorphism still has been round in Iew species.In the present study, three types （Type A, B and C） of 18S rDNA sequence coexisted in Cynoglossus lineolatusgenome, suggesting a non-concerted evolution process, rather than a strictly concerte...

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Bibliographic Details
Published in:海洋学报：英文版 2016, Vol.35 (12), p.38-50
Main Author: GONG Li SHI Wei YANG Min SI Lizhen KONG Xiaoyu
Format: Article
Language:English
Subjects:
Cynoglossus
evolution
lineolatus
non-concerted
nrDNA
polymorphism
pseudogene
repeat
tandem
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Summary:Although 188 rDNA sequence is extremely conservative, the polymorphism still has been round in Iew species.In the present study, three types （Type A, B and C） of 18S rDNA sequence coexisted in Cynoglossus lineolatusgenome, suggesting a non-concerted evolution process, rather than a strictly concerted evolution fashion.Based on the differences of sequence variation, GC content, secondary structure and minimum free energy,Types A and B were speculated as the potential pseudogenes. Additionally, a fascinating finding was a 189-bpduplication of 18S rDNA in Type A sequence. To our knowledge, this is the first report on such a longduplication in teleostean ribosomal DNA. Compared with several theories accounting for the formation oftandem repeats, the unequal crossing over model was thought to be the most likely mechanism to generate the189-bp duplication of 18S rDNA. These results not only provide a novel molecular evidence for the unequalcrossing over model, but also benefit for the further study on 18S rDNA in fishes.
ISSN:0253-505X
1869-1099