Abstract:Foxl2, an important member of the Fox (forkhead transcription factor) gene family, plays an important role in ovarian development and sex regulation. To explore the mode of expression regulation in the sex differentiation of the scallop Patinopecten yessoensis, we analyzed the Foxl2 gene sequence characteristics of P. yessoensis using bioinformatics methods, and the expression of Foxl2 in different tissues was detected via semi-quantitative real-time polymerase chain reaction (RT-PCR). Quantitative RT-PCR and in situ hybridization revealed the temporal and spatial expression changes of Foxl2 in the four stages of gonadal development (proliferation, growth, maturation, and emission stage). The results showed that the Foxl2 sequence of P. yessoensis contains the FH domain shared by the Fox gene family, and the multiple sequence comparison analysis showed that P. yessoensis has the highest similarity with Chlamys farreri and Pecten maximus (98% and 96%, respectively). The phylogenetic tree analysis showed that the Foxl2 gene is highly conserved in different species and in the process of evolution. The results of the quantitative analysis and in situ hybridization showed that the positive signal of the in situ hybridization was mainly located in the cytoplasm of the germ cells. A small amount of PyFoxl2 transcripts were detected in the gills, kidneys, hepatopancreas, and testes. The expression level of Foxl2 was the highest in the ovary and peaked in the mature stage of the ovary. In contrast, with the development of the testis and the gradual differentiation of the male gametes, the expression of Foxl2 showed a declining trend, which is consistent with the results of the in situ hybridization. In conclusion, Foxl2 may play a key role in the ovarian development of P. yessoensis. It is a key gene in the regulation of sex differentiation in female P. yessoensis. This study provides a theoretical basis for advancing our understanding of the sex differentiation and gonadal development of P. yessoensis.
