[Nondestructive measurement of cellular ATP contents in vegetables using UV-Vis-NIR spectroscopy].

The cellular ATP content level in agricultural products directly reflects cell viability, therefore it can be potentially used as an indicator of freshness and quality of agricultural products during storage. Spectral data of sample spinach leaves were obtained using a UV-Vis-NIR spectrophotometer UV-3600. Protoplast suspensions were prepared by following the conventional physical-chemical methods, and the ATP contents in protoplasts were determined by the firefly luciferase bioluminescence technology. Person's correlation analysis was performed to identify the key wavelengths. Models were developed for estimating the ATP contents in spinach protoplasts based on the two identified key wavelengths, i. e. the ultraviolet 298 nm and the near-infrared 730 nm wavelengths. Results showed that both of the two key wavelengths (298 and 730 nm) have a considerable promise in estimating the ATP content in spinach protoplasts (R2 = 0.802 9 and 0.901 respectively). The spectroscopy based estimation of cellular ATP content in vegetables proposed in this study provides a new approach to the accurate, rapid, and non-destructive evaluation of the freshness of vegetables.

[Effect of hyperbaric oxygen treatment on mitochondrial free radicals after transient focal cerebral ischemia in rats].

OBJECTIVE: To investigate the effect of hyperbaric oxygen(HBO)therapy on mitochondrial free radicals after transient focal cerebral ischemia in rats. METHODS: The male SD rats were randomly assigned into two groups, control and HBO groups. All animals were subjected to 90 min intra-luminal middle cerebral artery occlusion (MCAO) with the regional cerebral blood flow monitored in vivo by laser Doppler flowmetry. HBO treatment was performed in a pressure chamber with 100% O(2)(3 ATM 1 h) 3 h after ischemia. Twenty-four hours after ischemia, mitochondria in the ischemic core and penumbra were isolated and the contents of H(2)O(2), O(2)(*-), MDA, SOD, GSH-PX and GSH in mitochondria were measured respectively. RESULT: After cerebral ischemia-reperfusion, contents of mitochondrial H(2)O(2), O(2)(*-), MDA increased, while the SOD, GSH-PX and GSH in the mitochondria decreased significantly both in the ischemic core and the ischemic penumbra, compared with those in the normal controls(P<0.05). In the ischemic penumbra, HBO therapy increased significantly the content of O(2)(*-)(P<0.05), enhanced the activity of SOD, and decreased the level of MDA (P<0.05). However, HBO therapy did not change the level of MDA, though it also increased the content of O(2)(*-) and the activity of SOD in the ischemic core. HBO therapy had no significant effect on the contents of H(2)O(2), GSH-PX and GSH in the ischemic mitochondria. CONCLUSION: HBO therapy initiated early after acute transient cerebral ischemia in rats can increase the mitochondrial free radicals level, but also increase the activity of the anti-radical enzymes. HBO treatment inhibits the lipid peroxidation damage of mitochondria in the ischemic penumbra, but not in the ischemic core, which indicates that the mitochondrial function plays a role in the reaction of the free radical in the ischemic area after HBO therapy.

Effects of osmotic stress on antioxidant enzymes activities in leaf discs of PSAG12-IPT modified Gerbera.

Leaf senescence is often caused by water deficit and the chimeric gene P(SAG12)-IPT is an auto-regulated gene delaying leaf senescence. Using in vitro leaf discs culture system, the changes of contents of chlorophylls, carotenoids, soluble protein and thiobarbituric acid reactive substance (TBARS) and antioxidant enzymes activities were investigated during leaf senescence of P(SAGl2)-IPT modified gerbera induced by osmotic stress compared with the control plant (wild type). Leaf discs were incubated in 20%, 40% (w/v) polyethylene glycol (PEG) 6000 nutrient solution for 20 h under continuous light [130 micromol/(m(2) x s)]. The results showed that the contents of chlorophylls, carotenoids and soluble protein were decreased by osmotic stress with the decrease being more pronounced at 40% PEG, but that, at the same PEG concentration the decrease in the transgenic plants was significantly lower than that in the control plant. The activities of superoxide dismutase (SOD), catalases (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and dehydroascorbate reductase (DHAR) were stimulated by PEG treatment. However, the increases were higher in P(SAG12)-IPT transgenic plants than in the control plants, particularly at 40% PEG treatment. Lipid peroxidation (TBARS content) was increased by PEG treatment with the increase being much lower in transgenic plant than in the control plant. It could be concluded that the increases in the activities of antioxidant enzymes including SOD, CAT, APX, GPX and DHAR were responsible for the delay of leaf senescence induced by osmotic stress.

[Effects of exogenous silicon on active oxygen scavenging systems in chloroplasts of cucumber (Cucumis sativus L.) seedlings under salt stress].

With K(2)SiO(4) (1.0 mmol/L) treatment, the effects of Si on the distribution of Na(+), K(+) to chloroplasts and antioxidant system of cucumber leaves under 50 mmol/L NaCl stress were studied. The results showed that there was a selective transport of K(+) into the chloroplasts so that Na(+) content of chloroplasts was lower under Si treatment (Table 1); H(2)O(2) and MDA contents in chloroplasts were significantly decreased (Fig.1), and the activities of SOD, APX, GR and DHAR were increased simultaneity (Fig.2), and AsA, GSH contents were also increased in chloroplasts of salt-stressed cucumber by additional Si treatment (Fig.3). It may be concluded that Si could decrease absorption of Na(+) and increase ability of active oxygen scavenging in chloroplasts, therefore the injury of chloroplast membrane under salinity stress in cucumber was alleviated.

Subcellular distribution and chemical form of Cd and Cd-Zn interaction in different barley genotypes.

A hydroponic experiment was carried out to study the genotypic difference in subcellular distribution and chemical form of Cd and Zn uptake and their interaction in four barley genotypes. Increased Cd level in the medium caused a significant increase of Cd concentration in all fractions of roots/shoots, with most accumulation in FI (cell wall) and FIV (soluble). In root, the greatest amount of Cd was found in extraction solution of 2% HAC or 0.6M HCl, followed by 1M NaCl (20%), and lowest in extraction of 80% ethanol or d-H2O. While in shoot, the highest value of Cd accumulation was recorded in the fractions extracted by 1M NaCl and 2% HAC, followed by 0.6M HCl or d-H2O, and least in 80% ethanol extraction solution. There was a distinct difference among genotypes in Cd concentration in subcellular and chemical forms and it was found that the Cd-sensitive genotype Wumaoliuling, in comparison with the other three Cd-resistant genotypes, had higher Cd concentration in chloroplast-shoot/trophoplast-root (FII), membrane and organelle (FIII) and in inorganic and water-soluble Cd of roots, while lower in FI, FIV and pectates/protein integrated Cd. After 48 h of Cd treatment, the plants were replaced into Cd-free nutrient solution and grown for 72 h, a significant decrease in Cd concentration of root FI was observed, with less Cd reduction in Wumaoliuling. In comparison with control (no Cd), addition of Cd significantly increased Zn accumulation in chloroplast (FII), with least increase in Wumaoliuling. The Zn content in the other 3 fractions decreased significantly with addition of Cd, especially in roots, while Wumaoliuling was the most severely affected genotype. Moreover, it could be suggested Zn supplement could significantly reduce Cd concentration in root trophoplast and in shoot soluble fraction of Cd-treated plants.

Genotypic differences in effects of cadmium exposure on plant growth and contents of cadmium and elements in 14 cultivars of bai cai.

Fourteen cultivars of bai cai (Brassica campestris L. ssp. chinensis var. communis) were grown in the nutrient solutions containing 0-0.5 microg mL(-1) of cadmium (Cd) to investigate genotypic differences in the effects of Cd exposure on the plant growth and uptake and distribution of Cd in bai cai plants. The Cd exposure significantly reduced the dry and fresh weights of roots and shoots, the dry weight ratio of shoot/root (S/R), total biomass, and chlorophyll content (SPAD value). Cd concentrations in bai cai ranged from 13.3 to 74.9 microg g(-1) DW in shoots and from 163.1 to 574.7 microg g(-1) DW in roots under Cd exposure, respectively. The considerable genotypic differences of Cd concentrations and accumulations in both shoots and roots were observed among 14 bai cai cultivars. Moreover, Cd mainly accumulated in the roots. Cd also caused the changes of uptake and distribution of nutrients in bai cai and under the influence of cadmium, the concentration of potassium (K) decreased in shoot and increased in root. However, the concentrations of magnesium (Mg), phosphorus (P), manganese (Mn), boron (B), and iron (Fe) increased in shoots and decreased in roots. In addition, Cd exposure resulted in an increase in calcium (Ca), sulphur (S), and zinc (Zn) concentrations in both shoots and roots but had no significant effects on the whole uptake of the examined mineral nutrients except for S.