Document Type

Journal Article

Department/Unit

Department of Biology

Title

Hypoxia turns genotypic female medaka fish into phenotypic males

Language

English

Abstract

Hypoxia caused by eutrophication is amongst the most pressing global problems in aquatic systems. Notably, more than 400 "dead zones" have been identified worldwide, resulting in large scale collapse of fisheries and major changes in the structure and trophodynamics. Recent studies further discovered that hypoxia can also disrupt sex hormone metabolism and alter the sexual differentiation of fish, resulting in male biased F1 generations and therefore posing a threat to the sustainability of natural populations. However, it is not known whether, and if so how, hypoxia can also change the sex ratio in vertebrates that have sex-determining XX/XY chromosomes. Using the Japanese medaka (Oryzias latipes) as a model, we demonstrate, for the first time, that hypoxia can turn genotypic female fish with XX chromosomes into phenotypic males. Over half of the XX females exposed to hypoxia exhibit male secondary sexual characteristics and develop testis instead of ovary. We further revealed that hypoxia can: (a) down-regulate the vasa gene, which controls proliferation of primordial germ cells and gonadal sex differentiation into ovary, and (b) up-regulate the DMY gene which resides at the sex-determining locus of the Y chromosome, and direct testis differentiation. This is the first report that hypoxia can directly act on genes that regulate sex determination and differentiation, thereby turning genotypic females into phenotypic males and leading to a male-dominant F1 population. © 2014 Springer Science+Business Media.

Keywords

DMY, Hypoxia, Male biased F1 generation, Sex determination, vasa

Publication Date

2014

Source Publication Title

Ecotoxicology

Volume

23

Issue

7

Start Page

1260

End Page

1269

Publisher

Springer Verlag

DOI

10.1007/s10646-014-1269-8

Link to Publisher's Edition

http://dx.doi.org/10.1007/s10646-014-1269-8

ISSN (print)

09639292

ISSN (electronic)

15733017

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