ABSTRACT:We investigated the toxic effects of carbendazim and n-butyl isocyanate (BIC), metabolites of the fungicide benomyl, on development in the African clawed frog, Xenopus laevis. To test the toxic effects, frog embryo teratogenesis assays using Xenopus were performed. Embryos were exposed to various concentrations of carbendazim (0-7 lM) and BIC (0-0.2 lM). LC 100 for carbendazim and BIC were 7 and 0.2 lM, respectively, and the corresponding LC 50 , determined by probit analysis, were 5.606 and 0.135 lM. Exposure to carbendazim concentrations !3 lM and BIC concentrations !0.1 lM resulted in 10 different types of severe external malformation. Histological examinations revealed dysplasia of the brain, eyes, intestine, and somatic muscle, and swelling of the pronephric ducts. These phenomena were common in both test groups. The tissue-specific toxic effects were investigated with an animal cap assay. Neural tissues are normally induced at a high frequency by activin A, however, the induction of neural tissues was strongly inhibited by the addition of carbendazim. Conversely, the addition of BIC resulted in weak inhibition of neural tissues. Electron micrographs of animal cap explants revealed degeneration of cell junctions in the carbendazim-treated group, but not in the BIC-treated group. Numerous residual yolk platelets and mitochondrial degeneration were commonly observed in both test groups. The gene expression of cultivated animal cap explants was investigated by reverse transcriptase-polymerase chain reaction and revealed that expression of the neural-specific marker neural cell adhesion molecule was more strongly inhibited in the carbendazim-treated group than in the BIC-treated group. # 2008 Wiley Periodicals, Inc. Environ Toxicol 23: 131-144, 2008.

The AIP1 fraction, a small water-soluble fraction purified from Artemisia iwayomogi, was shown to increase antibody production and suppress transplanted tumor cell growth in mice. In order to understand its immunomodulating activity, we have examined the effect of the AIP1 on mouse thymocytes in vitro. Treatment of mouse thymocytes in culture with the fraction resulted in the suppression of the cell death and the extension of the cell survival. A mouse gene array provided a profile of gene expression change showing the pattern of up-and downregulated genes by the AIP1 treatment, suggesting that the Fas/FasL-dependent apoptosis pathway might be modulated by the fraction.

Apoptotic death of mouse thymocytes in vitro, as induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), involves the up-regulation of Fas gene expression, while a carbohydrate fraction, AIP1, from Artemisia iwayomogi suppresses the death of thymocytes in culture along with the down-regulation of Fas gene expression. We have now investigated whether the AIP1 fraction modulates TCDD-induced thymocyte death. When treated with TCDD and AIP1 fraction together, the thymocytes do not show apoptosis induced by the TCDD treatment. The AIP1 supplementation to the TCDD treatment also down-regulates the TCDD-induced Fas gene up-regulation. These findings indicate that the AIP1 fraction suppresses TCDD-induced thymocyte apoptosis through the modulation of Fas gene expression.

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