Fish Gonadogenesis. Part II: Molecular Biology and Genomics of Sex Differentiation

Abstract

The combined result of the mechanisms of sex determination and sex differentiation is the sex ratio of a population. Because sex-related growth dimorphism in fish is quite common, sex ratios influence population reproductive capacity and contribute to size variation and growth patterns before and after sexual maturation. This may have practical consequences for aquaculture and explains the interest in sex control to favor the sex with superior growth, better food conversion efficiency, later sexual maturation, or to prevent reproduction if both sexes mature before harvest. This review concentrates on recent research using molecular biology tools to broaden our understanding of the different aspects related to fish sex differentiation, both in model fish species and economically important species. The contribution of genomics to this field is mainly through the use of microarrays for the analysis of the transcriptome, to identify expression signatures associated with the development of a particular phenotype, or genes involved in the process of sex differentiation, both under normal conditions and after exposure to a particular natural or aquaculture environment.

Keywords:

• fish
• sex differentiation
• aromatase
• cyp19
• dmrt1
• sex steroids
• sex steroid receptors
• genomics
• microarrays

ACKNOWLEDGMENTS

This work has been carried out within the project “AQUAFUNC” (EU-SSA-022685) with financial support from the Commission of the European Communities. We wish to thank D. M Power and K. Sundell and the AQUAFUNC project for providing the opportunity to write this review. Thanks are due to N. Ospina-Álvarez for assistance with the bibliography and diagrams and to the helpful comments of two anonymous referees. Research at the lab of F. P was supported by the Spanish Ministry of Science and Innovation, Grants AGL2006–01359/ACU (“Sexgene”) and CSD2007–00002 (“Aquagenomics”) funded by the program Consolider-Ingenio 2010.