FLOW CYTOMETRIC ASSAY FOR IN-VIVO GENOTOXIC EFFECTS OF PESTICIDES IN GREEN FROGS (RANA-CLAMITANS)

Frogs from farming regions in Quebec suffer a suite of physical and ph ysiological problems associated with the use of agricultural pesticide s. Flow cytometry was used to compare incidence of abnormal DNA profil e, half-peak coefficient of variation (CV), and variation in genome si ze (pg DNA per haploid nucleus) between Green frogs (Rana clamitans) f rom such fanning areas (corn and potato fields) and control sites diss ociated from agricultural practices, to infer possible genomic manifes tations of pesticide use. There was a significant increase in abnormal DNA profile in individuals from corn fields relative to the control s ites (P<0.05). In all comparisons, adult frogs showed greater CVs than did juveniles (P<0.0001), Among adults, CVs were higher for samples t aken from both potato and corn fields relative to the control samples (P<0.005), while in juveniles, only individuals from corn plots showed elevated CVs relative to controls (P<0.05). Juveniles showing physica l deformity had significantly higher CVs than normal individuals (P<0. 05), although there were no similar correlations with physiological di sruption. Mean C-value (variation in DNA content) was different betwee n adults and juveniles in all treatments (P<0.0001), but there were no significant differences in mean C-value and variance of such among si milar age classes between treatments. The different classes of DNA dam age found in this study are reflective of either acute or cumulative p esticide toxicity, and are exhibited by both sick and apparently norma l individuals. We therefore believe flow cytometry to be a powerful te chnique for the measurement of pesticide-induced genomic disruption in amphibian populations. (C) 1997 Elsevier Science B.V.