Comparative evaluation of genotoxicity of captan in amphibian larvae (Xenopus laevis andPleurodeles waltl) using the comet assay and the micronucleus test

Abstract

Captan (N-trichloromethylthio-4-cyclohexene-1,2-dicarboximide) is a fungicide used to inhibit the growth of many types of fungi on plants used as foodstuffs. The toxic and genotoxic potentials of captan were evaluated with the micronucleus test (MNT; AFNOR,2000) and the comet assay (CA) using amphibian larvae (Xenopus laevis and Pleurodeles waltl). Acute toxicity results showed that captan was toxic (1) to Xenopus larvae exposed to from 2 mg/L to 125 or 62.5 microg/L, depending on the nature of the water [reconstituted water containing mineral salts or mineral water (MW; Volvic, Danone, France)] and (2) to Pleurodeles exposed to from 2 mg/L to 125 microg/L in both types of water. The MNT results obtained in MW showed that captan (62.5 microg/L) was genotoxic to Xenopus but not genotoxic to Pleurodeles at all concentrations tested. CA established that the genotoxicity of captan to Xenopus and Pleurodeles larvae depended on the concentration, the exposure times, and the comet parameters (tail DNA, TEM, OTM, and TL). The CA and MNT results were compared for their ability to detect DNA damage at the concentrations of captan and the exposure times applied. CA showed captan to be genotoxic from the first day of exposure. In amphibians, CA appears to be a sensitive and suitable method for detecting genotoxicity such as that caused by captan.

Cancer incidence among pesticide applicators exposed to captan in the Agricultural Health Study

“…Captan was shown to be acutely genotoxic to African clawed frogs and Spanish ribbed newts using the micronucleus test [7]. CD1 mice fed very high doses of captan developed duodenal adenomas and adenocarcinomas [8].…”

Assessment of the potentialin vivoecotoxicity of Double-Walled Carbon Nanotubes (DWNTs) in water, using the amphibianAmbystoma mexicanum

“…Thus, clastogenic compounds and spindle poisons both lead to an increase in the number of micronucleated cells. The micronucleus test has been widely used in many amphibian species in the laboratory (Pleurodeles waltl , Ambystoma mexicanum and Xenopus laevis ) (Jaylet et al 1986;Gauthier 1996;Ferrier et al 1998;Gauthier et al 2004;Mouchet et al 2006). This method has been documented in French recommendations, using axolotl larvae (AFNOR 1987) and standardized in pleurodeles and xenopus larvae (AFNOR 2000).…”

Methods for Genotoxicity Testing of Environmental Pollutants

“…The test has been applied to a broader range of aquatic organisms such as algae (Erbes et al 1997;Aoyama et al 2003), mussels (Nagarajappa et al 2006;Rank et al 2007), amphibians (Mouchet et al 2006;Huang et al 2007) and fish (Masuda et al 2004;Kosmehl et al 2008). The advantages of the comet assay include the following: (a) genotoxic damage is detected at the single cell level; (b) most eukaryotic cell types are suitable for the assay; (c) only a small number of cells are required; (d) it is generally faster to conduct and more sensitive than other available methods for the assessment of strand breaks; (e) DNA strand breaks form quickly following genotoxic exposure, allowing for an early response evaluation on biota.…”