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Effects of environmentally relevant concentrations of atrazine on gonadal development of snapping turtles ( Chelydra serpentina )
Author(s) -
De Solla Shane R.,
Martin Pamela A.,
Fernie Kimberly J.,
Park Brad J.,
Mayne Gregory
Publication year - 2006
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 - 10.1897/05-165r.1
Subject(s) - chelydra , atrazine , biology , incubation , estrogen , medicine , endocrinology , aromatase , development of the gonads , turtle (robot) , pesticide , ecology , gonad , biochemistry , genetics , cancer , breast cancer
Abstract The herbicide atrazine has been suspected of affecting sexual development by inducing aromatase, resulting in the increased conversion of androgens to estrogens. We used snapping turtles ( Chelydra serpentina ), a species in which sex is dependent on the production of estrogen through aromatase activity in a temperature‐dependent manner, to investigate if environmentally relevant exposures to atrazine affected gonadal development. Eggs were incubated in soil to which atrazine was applied at a typical field application rate (3.1 L/ha), 10‐fold this rate (31 L/ha), and a control rate (no atrazine) for the duration of embryonic development. The incubation temperature (25°C) was selected to produce only males. Although some males with testicular oocytes and females were produced in the atrazine‐treated groups (3.3–3.7%) but not in the control group, no statistical differences were found among treatments. Furthermore, snapping turtle eggs collected from natural nests in a corn field were incubated at the pivotal temperature (27.5°C) at which both males and females normally would be produced, and some males had oocytes in the testes (15.4%). The presence of low numbers of males with oocytes may be a natural phenomenon, and we have limited evidence to suggest that the presence of normal males with oocytes may represent a feminizing effect of atrazine. Histological examination of the thyroid gland revealed no effect on thyroid morphology.