Involvement of Transforming Growth Factor Beta Family Genes in Gonadal Differentiation in Japanese Eel, Anguilla japonica, According to Sex-Related Gene Expressions.

Ching-Fong Chang,Wen-Shiun Yueh,Sylvie Dufour,Chien-Ju Lin,Guan-Chung Wu,Zhen-Yuan Lei,Shan-Ru Jeng

doi:10.3390/cells10113007

Abstract

The gonochoristic feature with environmental sex determination that occurs during the yellow stage in the eel provides an interesting model to investigate the mechanisms of gonadal development. We previously studied various sex-related genes during gonadal sex differentiation in Japanese eels. In the present study, the members of transforming growth factor beta (TGF-β) superfamily were investigated. Transcript levels of anti-Müllerian hormone, its receptor, gonadal soma-derived factor (amh, amhr2, and gsdf, respectively) measured by real-time polymerase chain reaction (qPCR) showed a strong sexual dimorphism. Transcripts were dominantly expressed in the testis, and their levels significantly increased with testicular differentiation. In contrast, the expressions of amh, amhr2, and gsdf transcripts were low in the ovary of E2-feminized female eels. In situ hybridization detected gsdf (but not amh) transcript signals in undifferentiated gonads. amh and gsdf signals were localized to Sertoli cells and had increased significantly with testicular differentiation. Weak gsdf and no amh signals were detected in early ovaries of E2-feminized female eels. Transcript levels of amh and gsdf (not amhr2) decreased during human chorionic gonadotropin (HCG)-induced spermatogenesis in males. This study suggests that amh, amhr2, and especially gsdf might be involved in the gene pathway regulating testicular differentiation of Japanese eels.

Highlights

The eel (Anguilla spp.) is a catadromous basal teleost with a remarkable migratory life cycle
We found that the expression patterns of amhr2 were similar to its ligand during testicular differentiation; amhr2 might play a vital role during testicular differentiation in Japanese eels
(1) The expressions of TGF-β superfamily genes in the gonads were conducted from elvers, juvenile eels, to yellow eels including undifferentiated stage, differentiating stage, differentiated stage, and even up to pre-pubertal stage in male and female

Summary

Introduction

The eel (Anguilla spp.) is a catadromous basal teleost with a remarkable migratory life cycle. Mature eels spawn in the ocean, and leptocephali larvae drift toward the coast and metamorphose into glass eels, which grow in continental habitats and develop as yellow eels. Eels are gonochoristic species with gonadal differentiation occurring during the yellow eel phase [2]. Environmental factors, such as population density, temperature, pH, and social interactions, were proposed to prevail over genetic sex determination in eels [3,4]. The gonochoristic feature with an environmental sex determination pattern and gonadal differentiation occurring during the yellow stage in eels provides an interesting model for investigating the mechanism of both gonadal sex differentiation and development

Methods

Results

Discussion

Conclusion