The biological function of the aromatase gene (cyp19a) is to transform testosterone into estradiol, which is involved in ovarian differentiation and development. In the present study, in order to explore the role of cyp19a in sex differentiation of Culter alburnus, the full-length cDNA sequence was obtained, and the relationship between promoter CpG methylation and gene expression level of cyp19a during gonad development was analyzed. Our results showed that the C. alburnus cyp19a was 2009 bp in length, including a 364 bp 5′-UTR, a 91 bp 3′-UTR, and a 1554 bp open reading frame encoding 517 amino acids. Multi-alignment of CYP19a amino acid sequences in different vertebrates revealed that C. alburnus had high identity with Cyprinus carpio and Danio rerio, followed by Oryzias laticeps, Monopterus albus, and Cynoglossus semilaevis, and had close to 50% homology with Xenopus laevis, Trachemys scripta, Homo sapiens, and Mus musculus. The results of this phylogenetic tree were consistent with those arrived at by traditional morphology and biochemistry, revealing a similar evolutionary status. qRT-PCR experiments showed that cyp19a was only highly expressed in the ovary, was less abundant in the brain, and almost undetectable in other tissues. Moreover, sodium bisulfite genome sequencing found that promoter CpGs of cyp19a was hypermethylated in the testis, while a few scattered CGs were methylated in the ovary, which showed an inverse relationship between methylation level and gene expression. These findings demonstrate that C. alburnus cyp19a is a sex-related gene with sexual dimorphic expression, and epigenetic modifications may play an important role during gonad differentiation.
Culter alburnuscyp19aCpG methylation Gene expression Sex differentiation
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This work was financially supported by grants from Zhejiang Science and Technology Major Program (2016C02055-1), and Natural Science foundation of Huzhou (2017YZ02).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
The ethical committee of Zhejiang Institute of Freshwater Fisheries approved this study.
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