Vitellogenin detection in Caiman latirostris (Crocodylia: Alligatoridae). A tool to assess xenoestrogen exposure

REY F; RAMOS JG; STOKER C; BELDOMÉNICO PM; BUSSMANN LE; LUQUE EH; MUÑOZ DE TORO M

Tulane University, Health Science Center, New Orleans, Louisiana, USA

Congreso; E.hormone Congress, 2004; 2004

Environmental pollution with endocrine disrupting compounds (EDCs) has adverse effects onecosystem health. Caiman latirostris are widely distributed in South American aquaticecosystems. Caimans have physiological and ecological characteristics that would make themboth particularly vulnerable to EDCs exposure and an appropriate candidate as sentinel species.Vitellogenin (Vtg) is a yolk precursor protein, synthesized by the liver of oviparous vertebrates inresponse to estrogen. Males do not synthesize Vtg, unless they are exposed to xenoestrogens. Theaims of our study were to evaluate Vtg pattern of induction in juvenile males and to characterizeVtg as a biomarker to evidence xenoestrogen exposure. The first step was to develop a specificand sensitive assay for C. latirostris Vtg. Plasmatic Vtg from C. latirostris females injected withestradiol-17β (E2) was purified by precipitation with EDTA-MgCl2 followed by ionic exchangechromatography. Purified Vtg was used to generate a polyclonal antibody that was purified byaffinity chromatography. Western blots assessed the specificity of the antibody. A competitiveantibody capture ELISA was developed to quantify plasmatic Vtg, allowing detection of 1 ng/ml.Pre-induction plasmatic Vtg was not detectable in males. Vtg induction was evaluated in responseto one or two (7 days apart) low doses of E2. A priming effect was observed following the secondE2 dose with a 13-fold increase in circulating Vtg. Hepatic synthesis was confirmed byimmunohistochemistry. Results presented here suggest that detection of plasmatic Vtg in malecaimans might become a valuable tool for biomonitoring the environment for xenoestrogenpollution.