Autor(es):
Peixoto, Francisco 
; Vicente, Joaquim A. F. ; Madeira, Vítor M. C.
Data: 2003
Identificador Persistente: http://hdl.handle.net/10316/8147
Origem: Estudo Geral - Universidade de Coimbra
Detalhes do Documento
Comparative effects of herbicide dicamba and related compound on plant mitochon...
Descrição
The herbicide dicamba (3,6-dichloro-2-methoxybenzoic acid) was evaluated for its effects on bioenergetic activities of potato tuber mitochondria to elucidate putative mechanisms of action and to compare its toxicity with 2-chlorobenzoic acid. Dicamba (4 mumol/mg mitochondrial protein) induces a limited stimulation of state 4 respiration of ca. 10%, and the above concentrations significantly inhibit respiration, whereas 2-chlorobenzoic acid maximally stimulates state 4 respiration (ca. 50%) at about 25 mumol/mg mitochondrial protein. As opposed to these limited effects on state 4 respiration, transmembrane electrical potential is strongly decreased by dicamba and 2-chlorobenzoic acid. Dicamba (25 mumol/mg mitochondrial protein) collapses, almost completely, Deltapsi; similar concentrations of 2-chlorobenzoic acid promote Deltapsi drops of about 50%. Proton permeabilization partially contributes to Deltapsi collapse since swelling in K-acetate medium is stimulated, with dicamba promoting a stronger stimulation. The Deltapsi decrease induced by dicamba is not exclusively the result of a stimulation on the proton leak through the mitochondrial inner membrane, since there was no correspondence between the Deltapsi decrease and the change on the O2 consumption on state 4 respiration; on the contrary, for concentrations above 8 mumol/mg mitochondrial protein a strong inhibition was observed. Both compounds inhibit the activity of respiratory complexes II and III but complex IV is not significantly affected. Complex I seems to be sensitive to these xenobiotics. In conclusion, dicamba is a stronger mitochondrial respiratory chain inhibitor and uncoupler as compared to 2-chlorobenzoic acid. Apparently, the differences in the lipophilicity are related to the different activities on mitochondrial bioenergetics. © 2003 Wiley Periodicals, Inc. J Biochem Mol Toxicol 17:185-192, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10077 http://dx.doi.org/10.1002/jbt.10077
The herbicide dicamba (3,6-dichloro-2-methoxybenzoic acid) was evaluated for its effects on bioenergetic activities of potato tuber mitochondria to elucidate putative mechanisms of action and to compare its toxicity with 2-chlorobenzoic acid. Dicamba (4 mumol/mg mitochondrial protein) induces a limited stimulation of state 4 respiration of ca. 10%, and the above concentrations significantly inhibit respiration, whereas 2-chlorobenzoic acid maximally stimulates state 4 respiration (ca. 50%) at about 25 mumol/mg mitochondrial protein. As opposed to these limited effects on state 4 respiration, transmembrane electrical potential is strongly decreased by dicamba and 2-chlorobenzoic acid. Dicamba (25 mumol/mg mitochondrial protein) collapses, almost completely, Deltapsi; similar concentrations of 2-chlorobenzoic acid promote Deltapsi drops of about 50%. Proton permeabilization partially contributes to Deltapsi collapse since swelling in K-acetate medium is stimulated, with dicamba promoting a stronger stimulation. The Deltapsi decrease induced by dicamba is not exclusively the result of a stimulation on the proton leak through the mitochondrial inner membrane, since there was no correspondence between the Deltapsi decrease and the change on the O2 consumption on state 4 respiration; on the contrary, for concentrations above 8 mumol/mg mitochondrial protein a strong inhibition was observed. Both compounds inhibit the activity of respiratory complexes II and III but complex IV is not significantly affected. Complex I seems to be sensitive to these xenobiotics. In conclusion, dicamba is a stronger mitochondrial respiratory chain inhibitor and uncoupler as compared to 2-chlorobenzoic acid. Apparently, the differences in the lipophilicity are related to the different activities on mitochondrial bioenergetics. © 2003 Wiley Periodicals, Inc. J Biochem Mol Toxicol 17:185-192, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10077 http://dx.doi.org/10.1002/jbt.10077
Tipo de Documento
Artigo
Idioma Inglês
Idioma Inglês
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