“Comet” Assay in seeds of the emergent aquatic plant Bidens laevis L. exposed to the insecticide endosulfán.

PÉREZ DJ., ; MENONE ML, ; CAMADRO EL; MADRID EA

Milán

Congreso; SETAC Europe 21st Annual Meeting; 2011

SETAC Europa

The increasing release of genotoxic chemicals into the environment is negatively affecting the ecosystems and the health of diverse organisms. Plant bioassays can be an integral part of test batteries used for the detection of genotoxic-carcinogenic environmental contamination of the aquatic environment. In fact, highly sensitive, time- and cost-effective plant models have been developed for the detection of toxic compounds arising from the use of pesticides. Plant response to mutagenic treatments can be considered on different levels of organization: the DNA molecule, the chromosome, and the genome up to the whole organism. In previous studies, we identified the emergent aquatic macrophyte Bidens laevis as a sensitive species able to show increased frequencies of chromosomal aberrations under exposure to endosulfan. However, for detecting genotoxicity at the molecular level, the “comet” assay is widely used. The goals of this work were, in seeds of Bidens laevis: 1) to find a suitable concentration of methyl methanesulfonate (MMS) to be used as positive control for the “comet” assay and 2) to study the potential clastogenic effect of endosulfan. A sample of seeds were exposed to 0; 10; 20; 100; 500 and 1000 mg/L MMS during 48 h (n=8) whereas another sample was exposed to 0; 0,02; 0,5; 5; 10; 50 and 100 ug/L endosulfan (n=10) at room temperature in the darkness; using a negative control and 20 mg/L MMS as positive control. The alkaline technique of the plant “comet” assay was used. At 10 and 20 mg/L MMS, normal germinative power was obtained while higher concentrations caused inhibition of germination and necrosis of the seed. Notwithstanding, a significant increase of the damage index (DI) with respect to the negative control was found at 20 mg/L MMS (p<0.05). Radicles from seeds exposed to endosulfan did not differ in their DI from the negative control at any concentration (p>0.05), indicating that this insecticide is aneugenic instead of clastogenic in B. laevis as we have previously demonstrated working with roots.