RESUMO
Upon transition of Mycobacterium smegmatis into the dormant state, accumulation of a dark brown fluorescent pigment was observed. This pigment gave bright red fluorescence in both cells and the culture medium. Based on 1H-NMR, MALDI and UV spectra, the fluorescent compounds, extracted from the culture medium as well as from the dormant cells, were concluded to be a mixture of free coproporphyrin III and uroporphyrin III and their corresponding methyl esters. A possible significance of porphyrin pigment accumulation in the dormant cells is discussed.
Assuntos
Mycobacterium smegmatis/química , Pigmentos Biológicos/química , Pigmentos Biológicos/isolamento & purificação , Porfirinas/química , Coproporfirinas/química , Coproporfirinas/isolamento & purificação , Meios de Cultura/química , Fluorescência , Mycobacterium smegmatis/fisiologia , Porfirinas/isolamento & purificação , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Uroporfirinas/química , Uroporfirinas/isolamento & purificaçãoRESUMO
The lectins of associative nitrogen-fixing bacteria Azospirillum brasilense Sp7 and its mutant A. brasilense Sp7.2.3 were shown to have different effects on the components of the wheat seedling root signal system, namely to regulate the levels of cAMP, nitric oxide, diacylglycerol, and salicylic acid, as well as to induce the activities of superoxide dismutase and lipoxygenase. Our results make it possible to consider azospirilla lectins as inducers of the signal systems in wheat seedling roots, since they cause development of several flows of primary signals. These data are of general biological importance, since lectins are present in all living organisms and most ot the functions of lectins remain insufficiently understood.
Assuntos
Azospirillum brasilense/fisiologia , Lectinas/metabolismo , Raízes de Plantas/metabolismo , Plântula/metabolismo , Triticum/microbiologia , Azospirillum brasilense/genética , Diglicerídeos/metabolismo , Lectinas/farmacologia , Lipoxigenase/metabolismo , Óxido Nítrico/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/microbiologia , Plântula/efeitos dos fármacos , Plântula/microbiologia , Transdução de Sinais , Superóxido Dismutase/metabolismo , Triticum/efeitos dos fármacos , Triticum/metabolismoRESUMO
The time course of changes in the endogenous content of salicylic acid, the ratio between the acid's free and bound forms, and changes in the activities of phenylalanine ammonia-lyase and catalase in wheat seedling roots under the effect of lectins of two strains of the associative nitrogen-fixing bacterium Azospirillum (A. brasilense Sp7 and its mutant defective in lectin activity, A. brasilense Sp7.2.3) is investigated. Differences in plant response to the action of the lectins from these two strains are established. On the basis of the obtained data, a model is proposed for lectin-assisted induction of resistance, according to which the lectin effect on the roots of seedlings results in the accumulation of free salicylic acid, which inhibits catalase activity, ultimately leading to accumulation of hydrogen peroxide and formation of induced resistance.
