Cellular homeostasis of S-nitrosoglutathione (GSNO), a major cache of nitric oxide bioactivity in plants, is controlled by the NADH-dependent S-nitrosoglutathione reductase (GSNOR) belonging to the family of class III alcohol dehydrogenases (EC 1.1.1.1). GSNOR is a key regulator of S-nitrosothiol metabolism and is involved in plant responses to abiotic and biotic stresses. This study was focused on GSNOR from two important crop plants, cauliflower (Brassica oleracea var. botrytis, BoGSNOR) and lettuce (Lactuca sativa, LsGSNOR). Both purified recombinant GSNORs were characterized in vitro and found to exists as dimers, exhibit high thermal stability and substrate preference towards GSNO, although both enzymes have dehydrogenase activity with a broad range of long-chain alcohols and ω-hydroxy fatty acids in presence of NAD+. Data on enzyme affinities to their cofactors NADH and NAD+ obtained by isothermal titration calorimetry suggest the high affinity to NADH might underline the GSNOR capacity to function in the intracellular environment. GSNOR activity and gene expression peak during early developmental stages of lettuce and cauliflower at 20 and 30 days after germination, respectively. GSNOR activity was also measured in four other Lactuca spp. genotypes with different degree of resistance to biotrophic pathogen Bremia lactucae. Higher GSNOR activities were found in non-infected plants of susceptible genotypes L. sativa UCDM2 and L. serriola as compared to resistant genotypes. GSNOR and GSNO were localized by confocal laser scanning microscopy in vascular bundles and in epidermal and parenchymal cells of leaf cross-sections. The presented results bring new insight in the role of GSNOR in the regulation of S-nitrosothiol levels in plant growth and development.
Zjišťovali jsme antimutagenní aktivitu brokolicové šťávy ošetřené vysokotlakou metodou, 500 MPa po dobu 10 minut. Tento způsob ošetření potlačuje růst mikroorganismů při zachování nutričně významných látek. Brokolice obsahuje vysoké množství glukosinolátů, jejichž degradační produkty (isothiokyanáty) vykazují výrazné antimutagenní a antikarcinogenní účinky. Za použití in vivo mikronukleus testu jsme sledovali inhibici mutagenity 2-amino-3-methyl-3H-imidazo-(4,5-f)-chinolinu (IQ). Čtrnáctidenní aplikace brokolicové šťávy pokusným zvířatům vedla ke statisticky významnému snížení počtu mikrojader vyvolaných aplikací IQ.
We established antimutagenic activity of broccoli juice, treated by high pressure method, 500 MPa for a period of 10 minutes. This technique of treatment suppresses the growth of microorganisms at simultaneous conservation of nutritionally important substances. Broccoli contains high amount of glucosinolates, degradation products of which (isothiocyanates) show distinctive antimutagenic and anticarcinogenic effects. We monitored the inhibition of mutagenicity of 2-amino-3-methyl-3H-imidazo-(4,5- f)-quinoline (IQ). Fourteen-day' s application of broccoli juice to experimental animals leads to statistically significant decrease of micronuclei, caused by the application of IQ mutagen.
