Sexual plasticity: A fishy tale.

Hui Liu,John R Godwin,Neil J Gemmell,Melissa S Lamm,P Mark Lokman,Erica V Todd

doi:10.1002/mrd.22691

Hui Liu, John R Godwin + Show 4 more

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https://doi.org/10.1002/mrd.22691

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Abstract

Teleost fish exhibit remarkably diverse and plastic patterns of sexual development. One of the most fascinating modes of plasticity is functional sex change, which is widespread in marine fish including species of commercial importance; however, the regulatory mechanisms remain elusive. In this review, we explore such sexual plasticity in fish, using the bluehead wrasse (Thalassoma bifasciatum) as the primary model. Synthesizing current knowledge, we propose that cortisol and key neurochemicals modulate gonadotropin releasing hormone and luteinizing hormone signaling to promote socially controlled sex change in protogynous fish. Future large-scale genomic analyses and systematic comparisons among species, combined with manipulation studies, will likely uncover the common and unique pathways governing this astonishing transformation. Revealing the molecular and neuroendocrine mechanisms underlying sex change in fish will greatly enhance our understanding of vertebrate sex determination and differentiation as well as phenotypic plasticity in response to environmental influences. Mol. Reprod. Dev. 84: 171-194, 2017. © 2016 Wiley Periodicals, Inc.

Highlights

Sexual expression in most sexually reproducing organisms is dichotomous and static, a sexual mode termed “gonochorism” (Policansky, 1982)
Future large-scale genomic analyses and systematic comparisons t among species, combined with manipulation studies, will likely uncover the rip common and unique pathways governing this astonishing transformation. c Revealing the molecular and neuroendocrine mechanisms underlying sex us change in fish will greatly enhance our understanding of vertebrate sex an determination and differentiation as well as phenotypic plasticity in response M to environmental influences. thor Key words: sexual plasticity, protogynous, gonadal, sex change, teleost fish, Au bluehead wrasse, regulatory mechanism
The vast majority of vertebrates are gonochoristic, with sexual fate initiated during embryonic development through a process that consists of primary “sex determination”, the early decision in an initially bipotential gonad to develop as an ovary or a testis, and “sex differentiation”, the subsequent gonadal differentiation and associated physiological activities (DeFalco and Capel, 2009)

Summary

Introduction

Sexual expression in most sexually reproducing organisms is dichotomous and static, a sexual mode termed “gonochorism” (Policansky, 1982). Cyp19a1a is highly expressed in the tho ovary of mature females, but is down-regulated in transitioning gonads (Zhang Au et al, 2008; Liu, 2016), where E2 levels drop to induce follicle atresia during protogynous sex change (see above).

Results

Conclusion