PM11 Wildlife Ecotoxicology
Exhibit Hall
8:00 AM - Monday
(PM185) Mixed function oxygenase enzymes in juvenile and adult frogs from atrazine-exposed sites in Michigan.
Murphy, M1, Tompsett, A1, Coady, K2, Hecker, M1, Jones, P1, Giesy, J1, Carr, J3, Smith, E3, Van Der Kraak, G4, Kendall, R3, 1 Michigan State University, East Lansing, MI, USA2 Entrix, Inc., Okemos, MI, USA3 Texas Tech University, Lubbock, TX, USA4 University of Guelph, Guelph, ON, Canada
ABSTRACT- Exposure to atrazine has been reported to cause gonadal deformities and affect plasma hormone concentrations and aromatase activities in frogs in laboratory exposures, but little is known about possible effects on wild frog populations. Adult and juvenile green frogs (Rana clamitans), American bullfrogs (Rana catesbeiana) and northern leopard frogs (Rana pipiens) were collected throughout the summers of 2002 and 2003 from fifteen field sites in central Michigan representing a range of atrazine exposure concentrations. Atrazine concentrations were greatest in early to mid-summer, ranging from <0.22 to >250 
g/L across all sites. One gonad was removed from each frog for measurement of aromatase (CYP19) activity. Livers were removed from all frogs and microsomes were tested for EROD, MROD and PROD enzyme activities. Aromatase activities ranged in adult frogs from undetectable to >1000 fmol/hr/mg protein, and in juvenile frogs from undetectable to >6 fmol/hr/mg protein. EROD values in adults ranged from <1 pM/min/mg protein to > 80 pM/min/mg protein, and in juveniles from <1 pM/min/mg protein to >100 pM/min/mg protein. MROD values were generally less than EROD values, ranging from <1 pM/min/mg protein to >30 pM/min/mg protein in adults. Comparisons were made between collection sites to determine whether atrazine concentrations in water were correlated with the measured parameters.
Key words: atrazine, frog, mixed function oxygenase, biomarker