TP17 Biomarkers
Tuesday, 15 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(ROY-1117-831197) A non-specific ELISA to measure vitellogenin in the copper redhorse (Moxostoma hubbsi) - a threatened species in Quebec.

Roy, R.¹, Maltais, D.¹, Allaire, M.¹, Couillard, C.¹, ¹ Fisheries and Oceans Canada, Mont-Joli, Quebec, Canada

ABSTRACT- The copper redhorse (Moxostoma hubbsi) is Quebec's only indigenous fish species and is listed as "threatened" under Canada's Species at Risk Act. It is suspected that endocrine disruptive chemicals (EDCS), such as pesticides or alkylphenols, contribute to the spawning difficulties encountered by this species. The female egg-protein vitellogenin (VTG) is present in surface mucus of vitellogenic female fish and has been used to distinguish sex or determine the state of maturity. Sampling mucus is potentially less stressful for evaluating effects of EDCs than collecting a blood sample. There is no homologous enzyme immunoassay (EIA) for catostomid VTG, yet an EIA for carp VTG (cVTG) is available. The objectives of this study were (i) to evaluate the cVTG EIA for use with a species of redhorse and (ii) to determine if VTG in surface mucus can be used as a biomarker for exposure to EDCs. For conservation reasons, this study was conducted with the shorthead redhorse (Moxostoma macrolepiotum). A small number (4 of each sex) of this species were captured and brought to the IML. After a period of acclimation, mucus and plasma samples were collected and later analysed for VTG. The males were also injected with estradiol (E2) and plasma VTG levels were followed for several weeks after. Vitellogenic females could be differentiated from males and non-vitellogenic females using the cVTG EIA. Levels of apparent VTG in E2-induced males were proportional with degree of induction. Apparent VTG was detected in mucus collected from E2-induced males, but there was only a weak relationship with levels in plasma. We conclude that the cVTG EIA has the potential to detect exposure to EDCs in the redhorse. The technique can now be tested with the copper redhorse under field conditions to evaluate its role in recovery plans for this endangered species.

Key words: vitellogenin, Moxostoma, endangered, EIA