RESUMO
Dicamba is a benzoic acid herbicide used to target woody and broadleaf weeds in industrial, domestic, and municipal spheres. Because of its widespread use, dicamba is frequently detected in surface waters near sites of application. However, little is known regarding the effects of dicamba on freshwater fishes. In the present study, primary cultures of hepatocytes from rainbow trout (Oncorhynchus mykiss) were exposed to either an environmentally relevant (0.22 or 2.2 µg L-1) or supra-environmental (22 µg L-1) concentration of dicamba for 48 h to investigate if oxidative stress is a mechanism of toxicity. mRNA abundances of genes involved in the response to oxidative stress, levels of lipid peroxidation, and concentrations of glutathione and s-adenosyl methionine (SAM) were quantified. Results indicate that dicamba does not induce oxidative stress. However, exposure to 2.2 µg L-1 of dicamba did cause a 5.24-fold increase in concentrations of SAM. To investigate the mechanisms of increased SAM, effects of dicamba on global and genome-wide DNA methylation were quantified. Dicamba did not cause changes to DNA methylation. Overall, dicamba was not acutely toxic to hepatocytes and did not cause oxidative stress or changes in DNA methylation at environmentally relevant concentrations.
Assuntos
Metilação de DNA , Dicamba/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Hepatócitos/metabolismo , Estresse Oxidativo , S-Adenosilmetionina/metabolismo , Animais , Genoma , Hepatócitos/efeitos dos fármacos , Herbicidas/farmacologia , Peroxidação de Lipídeos , Oncorhynchus mykissRESUMO
The advent of biotechnology-derived, herbicide-resistant crops has revolutionized farming practices in many countries. Facile, highly effective, environmentally sound, and profitable weed control methods have been rapidly adopted by crop producers who value the benefits associated with biotechnology-derived weed management traits. But a rapid rise in the populations of several troublesome weeds that are tolerant or resistant to herbicides currently used in conjunction with herbicide-resistant crops may signify that the useful lifetime of these economically important weed management traits will be cut short. We describe the development of soybean and other broadleaf plant species resistant to dicamba, a widely used, inexpensive, and environmentally safe herbicide. The dicamba resistance technology will augment current herbicide resistance technologies and extend their effective lifetime. Attributes of both nuclear- and chloroplast-encoded dicamba resistance genes that affect the potency and expected durability of the herbicide resistance trait are examined.
Assuntos
Dicamba/farmacologia , Glycine max/efeitos dos fármacos , Herbicidas/farmacologia , Oxigenases de Função Mista/genética , Agricultura , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Cloroplastos/genética , Resistência a Medicamentos/genética , Engenharia Genética , Vetores Genéticos , Solanum lycopersicum/efeitos dos fármacos , Solanum lycopersicum/genética , Oxigenases de Função Mista/metabolismo , Dados de Sequência Molecular , Oxirredutases O-Desmetilantes/metabolismo , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/genética , Pseudomonas/enzimologia , Pseudomonas/genética , Glycine max/genética , Nicotiana/efeitos dos fármacos , Nicotiana/genéticaRESUMO
Since maize callus cultures regenerate plants via somatic embryogenesis, one might expect to find similar proteins in both zygotic embryos and tissue cultures. The 63-kD globulin protein designated GLB1, the expression of which is regulated by abscisic acid (ABA), is one such protein. When maize Type I regenerable callus was exposed for 24 h to 0.1 m M ABA or a water stress induced by 0.53 M mannitol, GLB1 was produced as determined by Western analysis. This protein was not detected in ABA or mannitol-treated regenerable cultured tissue of a null genotype or in tissues not exposed to ABA or water stress. Exposure to ABA in the culture medium increased the callus ABA levels greatly but a mannitol-induced water stress had only a small effect on ABA levels. Regenerable callus exposed to 0.1 m M ABA also produced mRNA that hybridized on a Northern blot with a globulin- 1 gene ( Glb1) probe. When both Type I and Type II regenerable cultured tissues were exposed to regeneration medium without ABA or mannitol, several GLB1 antibody immunoreactive proteins were produced. These proteins were not detected in regenerated plants nor in non-regenerable callus treated with ABA. These results suggest that: (1) at least for expression of Glb1, somatic embryogenesis is similar to zygotic embryogenesis, (2) there may be a regulatory role for auxin in the processing of Glb1-encoded polypeptides since fewer are seen when dicamba is present in the medium, (3) ABA has a role in somatic embryogenesis, and (4) regenerability of a maize callus culture may be assessed by treating the cultured tissue with 0.1 m M ABA to determine if GLB1 proteins are induced.
Assuntos
Proteínas de Plantas/genética , Zea mays/genética , Ácido Abscísico/farmacologia , Western Blotting , Técnicas de Cultura , Dicamba/farmacologia , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Manitol/farmacologia , Reguladores de Crescimento de Plantas/farmacologia , Proteínas de Plantas/metabolismo , RNA Mensageiro/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Regeneração/genética , Água/metabolismo , Zea mays/embriologia , Zea mays/fisiologiaRESUMO
Los herbicidas del tipo del dicamba son usados para control de malezas de hojas anchas. Este y los tipos fenoxiacético son formulados como ésteres o sales, conteniendo a veces hasta 50 por ciento de ingrediente activo. Se han reportado para éstos debilidad muscular y mneuropatías periférica luego de exposición ocupacional. Se considera que el dicamba tiene baja toxicidad aguda en el hombre. El objeto de esta presen5tación es mostrar dos cuadros clínicos severos provocados por la exposición accidental percutánea a un herbicida que lo contenía, en dos pacientes atendidos en el Hospital de Emergencias Clemente Alvarez(HECA) de Rosario. en 1993. Ambos pacientes, de 19 y 20 años desarrollaron cuadros clínicos similares, mialgias intensas y generalizadas, sudoración profusa y gran decaimiento. Presentaron cifras muy elevadas de transaminasas y CPK, por lo que se caracterizó el cuadro como rabdomiolisis. Rerquirieron internación en UTI, Un paciente hizo insuficiencia renal aguda que requirio diálisis renal. Evolucionaron lentamente. Durante su internación refirieron haber atravesado un campo recientemente fumigado con Misil, en zaballa, Provincia de Sante Fé, mojandose las ropas y no habiéndose lavado ni en ese momento ni en días posteriores. Las muestras tomadas al ingreso fueron procesadas en dos sistemas cromatográficos: HPLC y cromatografía gaseosa con detector de captura electrónica. Se usó como patrón un producto comercial por no disponer de standard puro. Ambos cromatogramas muestran pico compatible con dicamba. Posteriormente estos estudios fueron confirmados por GC-EM. Discutimos dificultades diagnósticas, características toxicocinéticas y compatibilidad del cuadro con dicha exposición, resaltando estos hallazgos por la escasa información sobre cuadros similares