University of Tasmania
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Masculinization of adult Gambusia holbrooki using 17α-methyltestosterone: a case of recapitulation of protogyny in a gonochorist?

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journal contribution
posted on 2023-05-21, 07:26 authored by Ngoc TranNgoc Tran, Tzu nin KwanTzu nin Kwan, Gary Purser, Jawahar PATIL
17α-Methyltestosterone (MT) is a synthetic steroid that has been widely used to masculinize many fish species when administered early during larval development, however, reports on its efficacy on adults is limited. To this end, this study investigated the efficacy of MT in the masculinization of the eastern mosquitofish (G. holbrooki) at two adult stages (maiden and repeat gravid females). The treated females were fed control or respective MT incorporated feed (0–200 mg/kg diet) for 50 days. Effects of the hormone on secondary sexual characteristics, internal gonad morphology, expression of the Anti-Müllerian Hormone (amh) gene and sexual behavior of the treated females were investigated. The results showed that MT at the dose of 50 mg/kg feed stimulated secondary sexual character development, upregulated expression of amh, formation of testicular tissue and a shift in the behavior similar to those of normal males, prominently so in treated maiden gravid females. Post-treatment, long-term observations indicated that only two masculinized females reverted back to being females and gave birth to young. Induction of masculinizing effects in most individuals suggests that the sexual phenotype of this species appears to be highly plastic with potential to sex reverse at adulthood. This in combination with its small size and short reproductive cycle could provide an ideal system to explore the mechanisms of sequential hermaphroditism in fish and contribute to genetic control of this pest fish.

Funding

Australian Research Council

Inland Fisheries Service

History

Publication title

Biology

Volume

11

Issue

5

Article number

694

Number

694

Pagination

1-23

ISSN

2079-7737

Department/School

Institute for Marine and Antarctic Studies

Publisher

MDPIAG

Place of publication

Switzerland

Rights statement

Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons 4.0 International (CC BY 4.0) license (https://creativecommons.org/licenses/by/4.0/).

Repository Status

  • Open

Socio-economic Objectives

Control of pests, diseases and exotic species in fresh, ground and surface water; Fresh, ground and surface water biodiversity