UBE2I stimulates female gonadal differentiation in chicken(Gallus gallus)embryos

Without known analogous sex-determining factors like SRY(sex determining region Y)in mammals,the chicken(Gallus gallus)sex determination mechanism still remains unclear,which highly restricts the biological research on chicken development and poultry single-sex reproduction.Here we not only characterized a new female-biased gene UBE2I and identified the expression pattern by qRT-PCR,but also described the functional role of UBE2I in the gonadal development of chicken embryos.Results showed that UBE2I exhibited a female-biased expression pattern in the early stage of PGCs(primordial germ cells)in embryonic gonads and robust expression in ovaries of newborn chickens.Most importantly,we successfully developed an effective method to interfere or overexpress UBE2I in chicken embryos through the intravascular injection.The qRT-PCR analysis showed that the sex-related genes(FOXL2,CYP19A1 and HINTW)in females were upregulated(P<0.05)under the overexpression of UBE2I and the sex-related genes(SOX9,DMRT1 and WT1)in females were downregulated(P<0.05)after interfering UBE2I.Furthermore,the change of UBE2I expression was associated with the level of estradiol and its receptors(AR and ESR),which suggests that UBE2I is necessary to initiate the female-specific development in chickens.In conclusion,this work demonstrates that UBE2I is a crucial sex differentiation-related gene in the embryonic development of chickens,which provides insights for further understanding the mechanism of sex determination in chickens.

Identification of global alternative splicing and sex-specific splicing via comparative transcriptome analysis of gonads of Chinese tongue sole(Cynoglossus semilaevis)

Chinese tongue sole(Cynoglossus semilaevis)is an economically important marine fish species with a ZZ/ZW sex determination mechanism,which can be influenced by temperature.Alternative splicing(AS)is an important mechanism regulating the expression of genes related to sex determination and gonadal differentiation,but has rarely been reported in fish.In this study,to explore the molecular regulatory mechanisms of sex determination and gonadal differentiation,we combined isoform and RNA sequencing(Iso-Seq and RNA-Seq)to perform transcriptome profiling of male and female gonads in C.semilaevis.In total,81883 and 32341 full-length transcripts were obtained in males and females,respectively.A total of 8279 AS genes were identified,including 2639 genes showing differential AS(DAS)between males and females.Many intersecting DAS genes and differentially expressed genes(DEGs)were enriched in the meiotic cell cycle pathway,and genes related to gonadal differentiation,such as esrrb and wt1a,were found to have sex-specific isoforms.Thus,this study revealed AS events in the gonadal transcriptomes of male and female C.semilaevis,described the characteristics of active transcription in the testes,and identified candidate genes for studying the regulatory mechanisms of AS during gonadal differentiation.

A landscape of differentiated biological processes involved in the initiation of sex differentiation in zebrafish

Zebrafish(Danio rerio)has been used as a promising animal model to study gonadal development and gametogenesis.Although previous studies have identified critical molecules participating in zebrafish gonad differentiation,a landscape view of the biological processes involved in this process is still lacking.Here we isolated intact zebrafish differentiating gonads,at 25 days post-fertilization(dpf)and 30 dpf and conducted RNA-seq analyses on the juvenile gonads that tended to develop into ovaries or testes.Our study demonstrates that the juvenile ovary and testis at 25 dpf and 30 dpf are different at the biological process level.During ovary differentiation,the biological processes related to metabolic activities in the production of energy and maternal substances,RNA degradation,and DNA repair were enriched.During testis differentiation,the biological processes related to cell proliferation,differentiation,and morphogenesis were enriched,with a total of 15 signaling pathways.Notably,we reveal that the immune-related processes are extensively involved in the regulation of testis development.Overall,this study provides a landscape of differentiated biological processes and novel insights into the initiation of sex differentiation in zebrafish.