RESUMO
Maintaining nitric oxide (NO) homeostasis is essential for normal plant physiological processes. However, very little is known about the mechanisms of NO modulation in plants. Here, we report a unique mechanism for the catabolism of NO based on the reaction with the plant hormone cytokinin. We screened for NO-insensitive mutants in Arabidopsis and isolated two allelic lines, cnu1-1 and 1-2 (continuous NO-unstressed 1), that were identified as the previously reported altered meristem program 1 (amp1) and as having elevated levels of cytokinins. A double mutant of cnu1-2 and nitric oxide overexpression 1 (nox1) reduced the severity of the phenotypes ascribed to excess NO levels as did treating the nox1 line with trans-zeatin, the predominant form of cytokinin in Arabidopsis. We further showed that peroxinitrite, an active NO derivative, can react with zeatin in vitro, which together with the results in vivo suggests that cytokinins suppress the action of NO most likely through direct interaction between them, leading to the reduction of endogenous NO levels. These results provide insights into NO signaling and regulation of its bioactivity in plants.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Citocininas/metabolismo , Óxido Nítrico/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Carboxipeptidases/genética , Carboxipeptidases/metabolismo , Citocininas/química , Citocininas/genética , Flores/crescimento & desenvolvimento , Flores/metabolismo , Genes de Plantas , Mutação , Doadores de Óxido Nítrico/farmacologia , Nitroprussiato/farmacologia , Ácido Peroxinitroso/metabolismo , Fenótipo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA de Plantas/genética , RNA de Plantas/metabolismo , Zeatina/metabolismo , Zeatina/farmacologiaRESUMO
OBJECTIVE: To develop a quantitative analytical procedure of scopolamine and atropine in Flos Daturae using RP-HPLC. METHOD: The two alkaloids were separated on a Hypersil BDS C18 column (4.6 mm x 250 mm, 5 microm) with a mobile phase of 0.02 mol x L(-1) sodium acetate buffer (containing 0.02% triethanolamine and the pH was adjusted to 6.0 with acetic acid)-methanol (60:40) and a detection wavelength of 215 nm. The flow rate was 1.0 mL x min(-1) and the column temperature was maintained at room temperature. RESULT: The mean recovery was (99.6 +/- 1.8)% for scopolamine and (100.4 +/- 1.5)% for atropine. CONCLUSION: This method was simple, accurate and sensitive.
Assuntos
Atropina/análise , Cromatografia Líquida de Alta Pressão/métodos , Datura/química , Plantas Medicinais/química , Escopolamina/análise , Flores/química , Reprodutibilidade dos TestesRESUMO
The principle and application in the environmental analysis of Solid Phase Extraction (SPE) combined with Room Temperature Phosphorescence (RTP) analysis were reviewed. The principle, device, separation modes, operation procedures and application of SPE were commented. The merits and shortages in the operation procedure and quantitative analysis of classic RTP were also summarized. The potential application in the trace sample analysis and the advantage of coupling technique of SPE and RTP were indicated. The sensitivity and selectivity of the coupling technique could be greatly increased because of the strong enrichment ability of the SPE materials and the high selectivity of RTP. So far the technique has been successfully used in the analysis of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans (PClDBFs) in the environmental samples according to their phosphorescence emission after preconcentration on the Whatman 1PS filter paper and C18 or C8 SPE membranes.
Assuntos
Benzofuranos/análise , Medições Luminescentes/métodos , Bifenilos Policlorados/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Extração em Fase Sólida/métodos , Adsorção , Benzofuranos/química , Bifenilos Policlorados/química , Hidrocarbonetos Policíclicos Aromáticos/química , Sensibilidade e Especificidade , TemperaturaRESUMO
A simple and rapid electrochemical method to detect the hydroxyl radical is described. This method employed the reaction between.OH and dimethyl sulfoxide (DMSO) to generate quantitatively formaldehyde, which then reacted with hydrazine hydrochloride at pH 6.2. The product showed a second-order derivative cathodic wave with the peak potential of -1.08 V( vsSCE) by single sweep oscillopolarography. The electrochemical behavior of the product was investigated by single sweep oscillopolarography and cyclic voltammetry. The experimental conditions for the measurement were optimized and the scavenging activity of some flavonoids on hydroxyl radicals was studied.