Hypoxia Affects Sex Differentiation and Development, Leading to a Male-Dominated Population in Zebrafish (Danio rerio)

• Published in: Environmental science & technology 2006-05, Vol.40 (9), p.3118-3122
• Main Authors: Yu, Richard M. K, Wu, Rudolf S. S
• Format: Article
• Language: English
• Subjects: Agnatha. Pisces; Animal populations; Animal, plant and microbial ecology; Animals; Applied ecology; Biological and medical sciences; Danio rerio; DNA Primers - chemistry; DNA, Complementary - metabolism; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on vertebrates; Environment; Estradiol - metabolism; Female; Fish; Freshwater; Fundamental and applied biological sciences. Psychology; Gender; Gene Expression; Genes; Hormones; Hypoxia; Male; Males; Reverse Transcriptase Polymerase Chain Reaction; Sex Characteristics; Sex Determination Processes; Sex Differentiation - physiology; Testosterone - metabolism; Water Pollutants, Chemical; Zebrafish
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es0522579

Hypoxia is affecting thousands of square kilometers of water and has caused declines in fish populations and major changes in aquatic communities worldwide. For the first time, we report that hypoxia can affect sex differentiation and sex development of zebrafish (Danio rerio), leading to a male-biased population in the F1 generation (74.4% ± 1.7% males in the hypoxic groups versus 61.9% ± 1.6% males in the normoxic groups, n = 5; p < 0.05, χ2 test). The increase in males was associated with downregulations of various genes controlling the synthesis of sex hormones (i.e., 3β-HSD, CYP11A, CYP19A, and CYP19B) as well as an increase in the testosterone/estradiol ratio. The male-dominated populations caused by hypoxia will have reduced reproductive success, thereby threatening the sustainability of natural fish populations.