Toxic effects of carbendazim and n-butyl isocyanate, metabolites of the fungicide benomyl, on early development in the African clawed frog, Xenopus laevis

Chun Sik Yoon, Jung Hyo Jin, Joo Hung Park, Chang Yeol Yeo, Song Ja Kim, Yong Gi Hwang, Sung Jin Hong, Seon Woo Cheong

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

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 μM) and BIC (0-0.2 μM). LC 100 for carbendazim and BIC were 7 and 0.2 μM, respectively, and the corresponding LC50, determined by probit analysis, were 5.606 and 0.135 μM. Exposure to carbendazim concentrations ≥3 μM and BIC concentrations ≥0.1 μM 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.

Original languageEnglish
Pages (from-to)131-144
Number of pages14
JournalEnvironmental Toxicology
Volume23
Issue number1
DOIs
StatePublished - 2008

Keywords

  • Carbendazim
  • FETAX
  • Malformation
  • n-butyl isocyanate
  • Xenopus

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