Genomic Approaches to Study Genetic and Environmental Influences on Fish Sex Determination and Differentiation

Francesc Piferrer,Laia Ribas,Noelia Díaz

doi:10.1007/s10126-012-9445-4

Abstract

The embryonic gonad is the only organ that takes two mutually exclusive differentiating pathways and hence gives rise to two different adult organs: testes or ovaries. The recent application of genomic tools including microarrays, next-generation sequencing approaches, and epigenetics can significantly contribute to decipher the molecular mechanisms involved in the processes of sex determination and sex differentiation. However, in fish, these studies are complicated by the fact that these processes depend, perhaps to a larger extent when compared to other vertebrates, on the interplay of genetic and environmental influences. Here, we review the advances made so far, taking into account different experimental approaches, and illustrate some technical complications deriving from the fact that as development progresses it becomes more and more difficult to distinguish whether changes in gene expression or DNA methylation patterns are the cause or the consequence of such developmental events. Finally, we suggest some avenues for further research in both model fish species and fish species facing specific problems within an aquaculture context.

Highlights

Background on Fish Sex Determination andDifferentiationSex ratios are an important aspect of populations because these determine their reproductive potential and directly influence growth dynamics, and this is very important in farmed animals and relevant in finfish aquaculture
The sex ratio is the product of sex determination, the genetic and/or environmental process that establishes the gender of an organism (Penman and Piferrer 2008), and of sex differentiation, the various genetic, physiological processes that transform an undifferentiated gonad into a testis or an ovary (Piferrer and Guiguen 2008) (Fig. 2a)
Sex determination in fish can range from genotypic to environmental sex determination (ESD), with temperaturedependent sex determination (TSD) being the most common type of ESD (Fig. 2b)

Summary

Introduction

Background on Fish Sex Determination andDifferentiationSex ratios are an important aspect of populations because these determine their reproductive potential and directly influence growth dynamics, and this is very important in farmed animals and relevant in finfish aquaculture. From the point of view of the biology of the species under study, the approach usually taken to study the genomics of fish sex determination and differentiation depends to a large extent on whether monosex populations are available.

Results

Conclusion