Induction of micronuclei and sister chromatid exchanges in sheep lymphocyte cultures by herbicide chloridazon

The effect of herbicide chloridazon was studied using induction of micronuclei (MN) and sister chromatid exchanges (SCE) in vitro. Inductions of these markers were measured in sheep peripheral lymphocytes with and without of metabolic activation (S-9 mix). Chloridazon affected both MN and SCE at all of the concentrations tested. Significant increases (P<0.05) were achieved at 7 x 10(-4) M in both tests. Neither of the lower concentrations (7 x 10(-5) M and 7 x 10(-6) M) did affect the MN or SCE values. The herbicide was also tested in presence of an S 9 mix activating fraction, in which significant increases of SCE levels were determined for concentrations of 7 x 10(-5) M and 7 x 10(-4) M (P<0.05 and 0.01, respectively). No induction of the cell cycle delay or reduction of proliferation index (PI) were detected. Chloridazon has, as shown in our assays, a weak influence on induction of tested chromosomal changes.