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Int. J. Mol. Sci. 2017, 18(3), 646;

Evolution of Fish Let-7 MicroRNAs and Their Expression Correlated to Growth Development in Blunt Snout Bream

College of Fisheries, Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education/Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China
Collaborative Innovation Center for Healthy Freshwater Aquaculture of Hubei Province, Hubei Provincial Engineering Laboratory for Pond Aquaculture, Wuhan 430070, China
Department of Molecular and Cellular Biology, University of California Davis, Davis, CA 95616, USA
Author to whom correspondence should be addressed.
Academic Editor: Y-h. Taguchi
Received: 28 January 2017 / Revised: 12 March 2017 / Accepted: 13 March 2017 / Published: 16 March 2017
(This article belongs to the Special Issue microRNA Regulation 2017)
Full-Text   |   PDF [4045 KB, uploaded 16 March 2017]   |  


The lethal-7 (let-7) miRNA, known as one of the first founding miRNAs, is present in multiple copies in a genome and has diverse functions in animals. In this study, comparative genomic analysis of let-7 miRNAs members in fish species indicated that let-7 miRNA is a sequence conserved family in fish, while different species have the variable gene copy numbers. Among the ten members including let-7a/b/c/d/e/f/g/h/i/j, the let-7a precursor sequence was more similar to ancestral sequences, whereas other let-7 miRNA members were separate from the late differentiation of let-7a. The mostly predicted target genes of let-7 miRNAs are involved in biological process, especially developmental process and growth through Gene Ontology (GO) enrichment analysis. In order to identify the possible different functions of these ten miRNAs in fish growth development, their expression levels were quantified in adult males and females of Megalobrama amblycephala, as well as in 3-, 6-, and 12-months-old individuals with relatively slow- and fast-growth rates. These ten miRNAs had similar tissue expression patterns between males and females, with higher expression levels in the brain and pituitary than that in other tissues (p < 0.05). Among these miRNAs, the relative expression level of let-7a was the highest among almost all the tested tissues, followed by let-7b, let-7d and let-7c/e/f/g/h/i/j. As to the groups with different growth rates, the expression levels of let-7 miRNAs in pituitary and brain from the slow-growth group were always significantly higher than that in the fast-growth group (p < 0.05). These results suggest that let-7 miRNA members could play an important role in the regulation of growth development in M. amblycephala through negatively regulating expression of their target genes. View Full-Text
Keywords: fish; Megalobrama amblycephala; let-7 miRNA; evolution; expression; growth development fish; Megalobrama amblycephala; let-7 miRNA; evolution; expression; growth development

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Zhao, B.-W.; Zhou, L.-F.; Liu, Y.-L.; Wan, S.-M.; Gao, Z.-X. Evolution of Fish Let-7 MicroRNAs and Their Expression Correlated to Growth Development in Blunt Snout Bream. Int. J. Mol. Sci. 2017, 18, 646.

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