The effect of organochlorines and heavy metals on sex steroid-binding proteins in vitro in the plasma of nesting green turtles, Chelonia mydas.
In this study on green turtles, Chelonia mydas, from Peninsular Malaysia, the effect of selected environmental toxicants was examined in vitro. Emphasis was placed on purported hormone-mimicking chemicals such as dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene, dieldrin, lead, zinc and copper. Five concentrations were used: high (1 mg/L), medium (10(-1) mg/L), low (10(-2) mg/L), very low (10(-6) mg/L) and control (diluted carrier solvent but no toxicants). The results suggest that environmental pesticides and heavy metals may significantly alter the binding of steroids [i.e. testosterone (T) and oestradiol] to the plasma proteins in vitro. Competition studies showed that only Cu competed for binding sites with testosterone in the plasma collected from nesting C. mydas. Dieldrin and all heavy metals competed with oestradiol for binding sites. Furthermore, testosterone binding affinity was affected at various DDT concentrations and was hypothesised that DDT in vivo may act to inhibit steroid-protein interactions in nesting C. mydas. Although the precise molecular mechanism is yet to be described, DDT could have an effect upon the protein conformation thus affecting T binding (e.g. the T binding site on the steroid hormone binding protein molecule).
Ikonomopoulou
Maria Petrou
MP
School of Biomedical Sciences, Anatomy and Developmental Biology, The University of Queensland, Brisbane, QLD 4072, Australia. m.ikonomopoulou@uq.edu.au
Olszowy
Henry
H
Hodge
Mary
M
Bradley
Adrian J
AJ
D000818:Animals; D001667:Binding, Competitive; D003300:Copper / Q000633:toxicity; D003634:DDT / Q000633:toxicity; D003633:Dichlorodiphenyl Dichloroethylene / Q000633:toxicity; D004026:Dieldrin / Q000633:toxicity; D004958:Estradiol / Q000097:blood; D005260:Female; D006843:Hydrocarbons, Chlorinated / Q000633:toxicity*; D007854:Lead / Q000633:toxicity; D019216:Metals, Heavy / Q000633:toxicity*; D010575:Pesticides / Q000633:toxicity*; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism*; D013739:Testosterone / Q000097:blood; D014426:Turtles / Q000097:blood*; D015032:Zinc / Q000633:toxicity
D006843:Hydrocarbons, Chlorinated; D019216:Metals, Heavy; D010575:Pesticides; D012738:Sex Hormone-Binding Globulin; D007854:Lead; D013739:Testosterone; D003633:Dichlorodiphenyl Dichloroethylene; D004958:Estradiol; D003300:Copper; D003634:DDT; D004026:Dieldrin; D015032:Zinc