RESUMEN
Maleic hydrazide (MH) is an herbicide and is a regulator of the growth of buds in vegetables during storage. It is used in agriculture-in despite its known effect as a mutagenic and clastogenic agent. In this research the effect of MH on the root tips of Allium cepa L. was determined; correlations between the effects of different concentrations and exposure times on the mitotic index (MI) and induction of chromosomal aberrations (ChA) were also examined. Experiments were carried out in triplicate, using aqueous solutions of MH to concentrations of 10(-6), 10(-5), 10(-4) and 10(-3)M, at intervals of 0, 4, 8, 12, 24, and 48 h, with a control for each combination (with the MH substituted by distilled water). The results revealed an inhibition of the MI linked to the concentration and time of treatment (F=845.51, P<0.01 and F=427.58, P<0.01, respectively). For all the concentrations used and exposure periods longer than 12 h, different types of ChA were present, with significantly increased frequencies with increases in the concentration and time of exposure (P<0.01). To determine the mechanism through which the herbicide exerts its toxicity, ultrastructural electron microscopy was conducted. The results reveal nucleolar alterations, suggesting an inhibitory effect of biosynthetic activity.
Asunto(s)
Allium/genética , Aberraciones Cromosómicas/efectos de los fármacos , Exposición a Riesgos Ambientales , Herbicidas/toxicidad , Hidrazida Maleica/toxicidad , Daño del ADN , Herbicidas/farmacología , Hidrazida Maleica/farmacología , Microscopía Electrónica , Pruebas de Mutagenicidad , Raíces de PlantasRESUMEN
The aim of this investigation was to determine if extracts of Spirulina maxima reduce the genotoxic damage induced by maleic hydrazide (MH) using the Tradescantia biosssay. Two types of extracts from the alga were prepared: an aqueous extract with two different concentrations, 100 and 500 mg/ml, and a second one, the extract of a 1% solution of dimethyl sulfoxide (DMSO) which corresponded to 100 mg/ml of the alga. The capacity of MH to induce micronuclei (MN) was initially established by administering 0.005, 0.01, and 0.015 mg/ml of the chemical to the Tradescantia inflorescences, and observing its effect after 24 h.The results of this experiment showed a significant MN increase with the two high concentrations tested, although no dose-response effect was observed. For the anticlastogenic assay, the extracts of Spirulina were applied to the inflorescences alone or immediately before the application of MH (0.01 mg/ml) and the induced MN were observed 24 h later. We found that none of the extracts increased the MN level with respect to the untreated plants; also, that MH more or less doubled the basal micronuclei frequency, and finally, that all tested extracts reduced the genotoxic damage caused by MH. The inhibitory indices obtained for the aqueous extracts (100 and 500 mg/ml) and for the DMSO extract were respectively 59, 85, and 56.3%. These data indicate that Spirulina is an anticlastogenic agent and suggest that it is advisable to extend studies on this matter using other biological models.