Polymorphism in exons CpG rich regions of the cyp17-II gene affecting its mRNA expression and reproductive endocrine levels in female Japanese flounder (Paralichthys olivaceus).
Cytochrome P450c17-II (cyp17-II) gene is an important factor affecting the growth, gonad differentiation and development, and other reproductive traits of fish. There are three CpG rich regions in the coding region of cyp17-II gene in Japanese flounder (Paralichthys olivaceus). The aim of this study was to understand whether mutations in exons of the cyp17-II gene occured at CpG sites, and mutations and methylation status of those CpG sites were involved in regulation of the expression level of cyp17-II gene and the reproductive endocrine of Japanese flounder. The results showed that three single nucleotide polymorphisms (SNPs) were identified. SNP1 [(c. G594A (p.Gly 188Arg)] located in exon 4 of L1 locus, and SNP2 (c.A939G) and SNP3 (c.C975T) of L2 locus located in CpG rich region of the exon 6 of cyp17-II gene. Furthermore, the A to G transition at 939bp position added a new methylation site to the cyp17-II coding region. According to multiple-comparison analysis, two loci (L1 and L2) were significantly associated with serum testosterone (T) level (P<0.05) and the expression of cyp17-II in ovary (P<0.01). Intriguingly, individuals with GG genotype of L2 locus containing eight CpG methylation sites had significantly lower serum testosterone level and cyp17-II mRNA expression than those with AA genotype containing seven CpG methylation sites. Moreover, the CpG site was highly methylated (≥77.8%) at 938 bp position of individuals with GG genotype of L2 locus. These implied that the mutation and methylation status of the coding region of cyp17-II could influence the gene expression and the reproductive endocrine levels in female Japanese flounder and L2 locus could be regarded as a candidate genetic or epigenetic marker for Japanese flounder breeding programs.
Fisheries College, Ocean University of China, Qingdao 266003, PR China.
YuXia
Y
Ding
Feng
F
He
HaiShen
H
Wen
JiFang
J
Li
Kun
K
Qian
MeiLi
M
Chi
Meng
M
Ni
XiangHan
X
Yin
Yan
Y
Bu
YiJie
Y
Zhao
DongQian
D
Zhang
D000818:Animals; D018899:CpG Islands; D019175:DNA Methylation; D004252:DNA Mutational Analysis; D005091:Exons; D005260:Female; D005432:Flounder / Q000235:genetics* / Q000378:metabolism; D005838:Genotype; D020641:Polymorphism, Single Nucleotide; D012333:RNA, Messenger / Q000378:metabolism; D013254:Steroid 17-alpha-Hydroxylase / Q000235:genetics* / Q000378:metabolism; D013739:Testosterone / Q000097:blood*
D012333:RNA, Messenger; D013739:Testosterone; D013254:Steroid 17-alpha-Hydroxylase