Intersex occurrence in rainbow trout (Oncorhynchus mykiss) male fry chronically exposed to ethynylestradiol.

Depiereux, Sophie; Liagre, Mélanie; Danis, Lorraine; De Meulder, Bertrand; Depiereux, Eric; Segner, Helmut; Kestemont, Patrick (2014). Intersex occurrence in rainbow trout (Oncorhynchus mykiss) male fry chronically exposed to ethynylestradiol. PLoS ONE, 9(7), e98531. Public Library of Science 10.1371/journal.pone.0098531

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This study aimed to investigate the male-to-female morphological and physiological transdifferentiation process in rainbow trout (Oncorhynchus mykiss) exposed to exogenous estrogens. The first objective was to elucidate whether trout develop intersex gonads under exposure to low levels of estrogen. To this end, the gonads of an all-male population of fry exposed chronically (from 60 to 136 days post fertilization--dpf) to several doses (from environmentally relevant 0.01 µg/L to supra-environmental levels: 0.1, 1 and 10 µg/L) of the potent synthetic estrogen ethynylestradiol (EE2) were examined histologically. The morphological evaluations were underpinned by the analysis of gonad steroid (testosterone, estradiol and 11-ketotestosterone) levels and of brain and gonad gene expression, including estrogen-responsive genes and genes involved in sex differentiation in (gonads: cyp19a1a, ER isoforms, vtg, dmrt1, sox9a2; sdY; cyp11b; brain: cyp19a1b, ER isoforms). Intersex gonads were observed from the first concentration used (0.01 µg EE2/L) and sexual inversion could be detected from 0.1 µg EE2/L. This was accompanied by a linear decrease in 11-KT levels, whereas no effect on E2 and T levels was observed. Q-PCR results from the gonads showed downregulation of testicular markers (dmrt1, sox9a2; sdY; cyp11b) with increasing EE2 exposure concentrations, and upregulation of the female vtg gene. No evidence was found for a direct involvement of aromatase in the sex conversion process. The results from this study provide evidence that gonads of male trout respond to estrogen exposure by intersex formation and, with increasing concentration, by morphological and physiological conversion to phenotypic ovaries. However, supra-environmental estrogen concentrations are needed to induce these changes.

Item Type:

Journal Article (Original Article)

Division/Institute:

05 Veterinary Medicine > Department of Infectious Diseases and Pathobiology (DIP)
05 Veterinary Medicine > Department of Infectious Diseases and Pathobiology (DIP) > Center for Fish and Wildlife Health (FIWI)

UniBE Contributor:

Segner, Helmut

Subjects:

600 Technology > 630 Agriculture

ISSN:

1932-6203

Publisher:

Public Library of Science

Language:

English

Submitter:

Lucia Gugger-Raaflaub

Date Deposited:

31 Mar 2015 13:36

Last Modified:

31 Mar 2015 13:36

Publisher DOI:

10.1371/journal.pone.0098531

PubMed ID:

25033040

BORIS DOI:

10.7892/boris.65497

URI:

https://boris.unibe.ch/id/eprint/65497

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