Identification of Foxl2 in freshwater mussel Hyriopsis cumingii and its involvement in sex differentiation.
The freshwater mussel Hyriopsis cumingii, is the most important species for pearl culture in China. At present, the mechanisms underlying sex differentiation and determination remain unclear in this species. Herein the open reading frame (ORF) of Foxl2 from H. cumingii (Hc-Foxl2) was cloned, and Hc-Foxl2 expression levels in six tissues (the gonad, gill, adductor muscle, foot, mantle, and kidney) were determined. Further, we performed quantitative real-time PCR to compare expressions levels between 1 and 8 months of age and 1-, 2-, and 3-year-old H. cumingii. The localization of Hc-Foxl2 expression in the ovary was analyzed by in situ hybridization, and its function was explored using RNA interference. We found that the ORF region of Hc-Foxl2 was 1215 bp in length, encoded 404 amino acids, and contained conserved FH domains. Hc-Foxl2 was expressed in the male and female tissues, with the expression levels being significantly higher in the ovary than in the testis. In 1-8-month-old H. cumingii, Hc-Foxl2 was expressed at the highest level at 5 months of age, and the gonads began to differentiate at the same time. Moreover, in 1-, 2-, and 3-year-old individuals, Hc-Foxl2 expression levels in the ovaries gradually decreased, but they were higher than those in the testis. Strong hybridization signals for Hc-Foxl2 were detected on the oocyte membrane in 3-year-old female mussels. We also performed double-stranded RNA (dsRNA) interference experiments using three dsRNA strands, which were injected into 5-month-old H. cumingii; the interference effects were the best at 12 h and 48 h post-injection. After interference with Hc-Foxl2, the expression levels of Wnt4, which has an antagonistic relationship with Foxl2 during ovarian development, were slightly increased. Thus, we speculate that Hc-Foxl2 is a female-related gene in H. cumingii and that it is involved in sex differentiation and ovarian development.
['Wang|Guiling|G|', 'Dong|Saisai|S|', 'Guo|Pengfei|P|', 'Cui|Xiaoyu|X|', 'Duan|Shenghua|S|', 'Li|Jiale|J|']
D000595:Amino Acid Sequence D000818:Animals D001483:Base Sequence D049872:Bivalvia D003001:Cloning, Molecular D000074842:Forkhead Box Protein L2 D005618:Fresh Water D005786:Gene Expression Regulation D010802:Phylogeny D017385:Sequence Homology D012733:Sex Differentiation
Foxl2 Hyriopsis cumingii Sex differentiation In situ hybridization RNAi qRT-PCR