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Response of larval Xenopus laevis to atrazine: Assessment of growth, metamorphosis, and gonadal and laryngeal morphology
Author(s) -
Carr James A.,
Gentles Angie,
Smith Ernest E.,
Goleman Wanda L.,
Urquidi Lina J.,
Thuett Kerry,
Kendall Ronald J.,
Giesy John P.,
Gross Tim S.,
Solomon Keith R.,
Van Der Kraak Glen
Publication year - 2003
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620220222
Subject(s) - metamorphosis , atrazine , biology , larva , xenopus , hatching , bioassay , zoology , pesticide , toxicology , ecology , biochemistry , gene
Larval Xenopus laevis were exposed to one of four concentrations of atrazine (0, 1, 10, or 25 μg/L, 11 replicate tanks per treatment, 60–65 larvae per replicate) dissolved in an artificial pond water (frog embryo teratogenesis assay‐ Xenopus [FETAX]) medium beginning 48 h after hatching until the completion of metamorphosis. Separate groups of larvae (six replicate tanks per treatment, 60–65 larvae per replicate) were exposed to estradiol (100 μg/L), dihydrotestosterone (100 μg/L), or ethanol vehicle control dissolved in FETAX medium. None of the treatments affected posthatch mortality, larval growth, or metamorphosis. There were no treatment effects on sex ratios except for estradiol, which produced a greater percentage of female offspring. Exposure to either estradiol or 25 μg atrazine/L increased the incidence of intersex animals based on assessment of gonadal morphology. Atrazine did not reduce the size of the laryngeal dilator muscle, a sexually dimorphic muscle in this species. We conclude that environmentally relevant concentrations of atrazine do not influence metamorphosis or sex ratios and do not inhibit sexually dimorphic larynx growth in X. laevis . The incidence of atrazine‐induced intersex animals was small (<5%) and occurred only at the greatest concentration of atrazine tested, a concentration that is rarely observed in surface waters in the United States.