Suchergebnisse

13 pages, 4 figures, 2 tables ; Epigenetics integrates genomic and environmental information to produce a given phenotype. Here, the model of Conserved Epigenetic Regulation of Sex (CERS) is discussed. This model is based on our knowledge on genes involved in sexual development and on epigenetic regulation of gene expression activation and silencing. This model was recently postulated to be applied to the sexual development of fish, and it states that epigenetic and gene expression patterns are more associated with the development of a particular gonadal phenotype, e.g., testis differentiation, rather than with the intrinsic or extrinsic causes that lead to the development of this phenotype. This requires the existence of genes with different epigenetic modifications, for example, changes in DNA methylation levels associated with the development of a particular sex. Focusing on DNA methylation, the identification of CpGs, the methylation of which is linked to sex, constitutes the basis for the identification of Essential Epigenetic Marks (EEM). EEMs are defined as the number and identity of informative epigenetic marks that are strictly necessary, albeit perhaps not sufficient, to bring about a specific, measurable, phenotype of interest. Here, we provide a summary of the genes where DNA methylation has been investigated so far, focusing on fish. We found that cyp19a1a and dmrt1, two key genes for ovary and testis development, respectively, consistently show an inverse relationship between their DNA methylation and expression levels, thus following CERS predictions. However, in foxl2a, a pro-female gene, and amh, a pro-male gene, such relationship is not clear. The available data of other genes related to sexual development such as sox9, gsdf, and amhr2 are also discussed. Next, we discuss the use of CERS to make testable predictions of how sex is epigenetically regulated and to better understand sexual development, as well as the use of EEMs as tools for the diagnosis and prognosis of sex. We argue that CERS can aid in focusing research on the epigenetic regulation of sexual development not only in fish but also in vertebrates in general, particularly in reptiles with temperature sex-determination, and can be the basis for possible practical applications including sex control in aquaculture and also in conservation biology ; This study was supported by the Spanish Ministry of Science grants AGL2016–787107-R "Epimark" to FP and AGL2015-73864-JIN "Ambisex" to LR. DA was supported by an Epimark contract, AV and NS-B were supported by Spanish government scholarships (BES-2014-069051 and BES-2017-079744, respectively); LR and JM-P were supported by Ambisex contracts ; Peer Reviewed

15 pages, 6 figures, supplementary material https://doi.org/10.1007/s10126-019-09886-x ; The European sea bass is one of the most important cultured fish in Europe and has a marked sexual growth dimorphism in favor of females. It is a gonochoristic species with polygenic sex determination, where a combination between still undifferentiated genetic factors and environmental temperature determines sex ratios. The molecular mechanisms responsible for gonadal sex differentiation are still unknown. Here, we sampled fish during the gonadal developmental period (110 to 350 days post fertilization, dpf), and performed a comprehensive transcriptomic study by using a species-specific microarray. This analysis uncovered sex-specific gonadal transcriptomic profiles at each stage of development, identifying larger number of differentially expressed genes in ovaries when compared to testis. The expression patterns of 54 reproduction-related genes were analyzed. We found that hsd17β10 is a reliable marker of early ovarian differentiation. Further, three genes, pdgfb, snx1, and nfy, not previously related to fish sex differentiation, were tightly associated with testis development in the sea bass. Regarding signaling pathways, lysine degradation, bladder cancer, and NOD-like receptor signaling were enriched for ovarian development while eight pathways including basal transcription factors and steroid biosynthesis were enriched for testis development. Analysis of the transcription factor abundance showed an earlier increase in females than in males. Our results show that, although many players in the sex differentiation pathways are conserved among species, there are peculiarities in gene expression worth exploring. The genes identified in this study illustrate the diversity of players involved in fish sex differentiation and can become potential biomarkers for the management of sex ratios in the European sea bass and perhaps other cultured species ; This work was supported by Spanish Government Consolider-Ingenio 2010 grant "Aquagenomics" (ref. CDS2007-0002) to SMK, FM, SZ and FP. BC was supported by an Aquagenomics contract; LR was supported by Aquagenomics postdoctoral contract; ND was supported by Aquagenomics predoctoral contract. NSB was supported by AGL2016-78710-R ; Peer Reviewed