학술논문
The germline-specific expression of Foxl3a and its paralogous Foxl3b are associated with male gonadal differentiation in the Japanese eel, Anguilla japonica.
Document Type
Article
Author
Source
Subject
*ANGUILLA japonica
*SOMATIC cells
*ANGUILLA anguilla
*ACTINOPTERYGII
*SEX change in animals
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Language
ISSN
0016-6480
Abstract
• Foxl3 duplication is found in eels (Anguilla sp.). • Foxl3a and Foxl3b are exclusively expressed in undifferentiated gonads and differentiated testes. • Foxl3a and Foxl3b are expressed in germline cells in the testes. • Testicular expression of Foxl3a and Foxl3b is not directly influenced by sex steroids. Unlike its paralog Foxl2 , which is well known for its role in ovarian development in vertebrates, the function of Foxl3 is still unclear. Foxl3 is an ancient duplicated copy of Foxl2. It is present as a single copy in ray-finned fish. But, due to repeated losses, it is absent in most tetrapods. Our transcriptomic data, however, show that two Foxl3 s (Foxl3a and its paralog Foxl3b) are present in Japanese eel. Foxl3a is predominantly expressed in the pituitary, and Foxl3b is predominantly expressed in the gills. Both Foxl3 s show a sex-dimorphic expression, being higher expression in testes than in ovaries. Moreover, Foxl3a and Foxl3b were exclusively expressed during gonadal differentiation in control eels (100% male). Conversely, Foxl3a and Foxl3b significantly decreased after gonadal differentiation in E2-treated eels (100% female). Furthermore, in accordance the difference in adhesive ability between somatic cells and germline cells in testes, Foxl3 s showed a high expression in suspension cells (putative germline cells) and low expression in adhesive cells (putative somatic cells). In situ hybridization further showed that Foxl3a and Foxl3b were expressed in the testicular germline cells. In addition, Foxl3 s expression was not changed by sex steroids in in vitro testes culture. Taken together, our results suggest that the teleost-specific Foxl3 paralog was repeatedly lost in most fish after the third round of whole genome duplication. The two germline-expressed Foxl3 s had higher expression levels in males than in females during gonadal differentiation in Japanese eel. These results demonstrated that Foxl3 s might play an important role in germline sexual fate determination from ancient fish to modern fish. [ABSTRACT FROM AUTHOR]