The effects of the nephrotoxic, anticancer agents cisplatin (CDI)P) and carboplatin (CBDCA), and the free radical scavenger, stobadine, were investigated on lipid peroxidation (EI’O) of rat kidney homogenates and phosphatidylcholine (PC) liposomes. Kidney homogenates were incubated in air at 37 °C for 6-48 h and lipid peroxidation was detected spectroscopically as absorbance (533 nm) of the thiobarbituric acid- malondialdchyde (TBA-MDA) complex. CDDP (0.3-10 mmol.I'1) increased LPO of the homogenate. CBDCA decreased the TBA-MDA absorbance, yet was found to interfere with MDA, TBA and/or with the TBA-MDA complex. Thus when CBDCA is involved, the TBA- MDA method for detection of LPO is not suitable. Stobadine (0.1 mmol.I'1 ar>d 1 mmol.I1) inhibited LPO either in the control homogenate and in the homogenate where peroxidation was increased by CDDP. The effect of CDDP and CBDCA on peroxidation of PC liposomes was monitored as oxygen consumption using a Clark-type oxygen electrode. CDDP increased but CBDCA decreaed the rate of oxygen consumption during the peroxidation of liposomes induced by FcSO,». The results suggest that the effects of CDDP and CBDCA on LPO may be linked with their nephrotoxicity.
Calligonum caput-medusae is known to grow well when irrigated with water containing NaCl. The aim of this study was to investigate ecophysiological responses of C. caput-medusae to different NaCl concentrations. In our study, we examined the effect of 0, 50, 100, 200, and 400 mM NaCl. Our results demonstrated that maximum seedling growth occurred at 50 mM NaCl. Photosynthetic parameters, such as the photosynthetic pigment content and gas exchange parameters, correlated with growth response. High salinity (≥ 100 mM NaCl) resulted in a significant reduction of the plant growth. Similarly, marked declines in the pigment content, maximal efficiency of PSII photochemistry, net photosynthetic rate, transpiration rate, and stomatal conductance were also detected. However, intercellular CO2 concentration showed a biphasic response, decreasing with water containing less than 200 mM NaCl and increasing with NaCl concentration up to 400 mM. Water-use efficiency and intrinsic water-use efficiency exhibited the opposite response. The reduction of photosynthesis at the high NaCl concentration could be caused by nonstomatal factors. High salinity led also to a decrease in the relative water content and water potential. Correspondingly, an accumulation of soluble sugars and proline was also observed. Na+ and
Cl- concentrations increased in all tissues and K+ concentrations were maintained high during exposure to NaCl compared with the control. High salinity caused oxidative stress, which was evidenced by high malondialdehyde and hydrogen peroxide contents. In order to cope with oxidative stress, the activity of antioxidative enzymes increased to maximum after 50 mM NaCl treatment. The data reported in this study indicate that C. caput-medusae can be utilized in mild salinity-prone environments., Y. Lu, J.-Q. Lei, F.-J. Zeng, B. Zhang, G.-J. Liu, B. Liu, X.-Y. Li., and Obsahuje bibliografii
Heavy metals such as cadmium (Cd) may affect different physiological functions in plants. We carried out a hydroponic experiment under greenhouse conditions in order to evaluate the effect of Cd on photosynthetic and physiological parameters of safflower. The responses of six safflower genotypes (Nebraska-10, 2811, Kouseh, S149, C111, and K12) to four concentrations of CdCl2 (0, 1.5, 3, and 4.5 mg L-1) were examined. Mean shoot and root dry masses of safflower plants were reduced by nearly 57% after the treatment by 4.5 mg(CdCl2) L-1. Contrary to the mean proline content, which increased by 121%, the mean total leaf area per plant, net photosynthetic rate, stomatal conductance to the CO2, leaf chlorophyll a, b, and (a+b), carotenoid content, and quantum efficiency of PSII decreased by 84.4, 50.5, 50.0, 31.6, 32.2, 31.8, 32.9, and 11.2%, respectively, at the presence of 4.5 mg(CdCl2) L-1. The mean Cd concentration in shoots and roots of safflower genotypes exhibited 52- and 157-fold increase, respectively, due to the addition of 4.5 mg(CdCl2) L-1 to the growing media. The mean malondialdehyde content was enhanced by 110% with the increasing CdCl2 concentration, indicating the occurrence of a considerable lipid peroxidation in the plant tissues. Even though the membrane stability index was adversely affected by the application of 1.5 mg(CdCl2) L-1, the decrease ranged from 45 to 62% when plants were treated with 4.5 mg(CdCl2) L-1. Genotype Nebraska-10 seemed to be different from the remaining genotypes in response to the 4.5 mg(CdCl2) L-1; its net photosynthetic rate tended to be the greatest and the Cd concentration in shoots and roots was the lowest among genotypes studied. This study proved Cd-induced decline in growth, photosynthesis, and physiological functions of safflower., L. Moradi, P. Ehsanzadeh., and Obsahuje seznam literatury
Cr(VI) significantly reduced rates of net photosynthesis and transpiration and of stomatal conductance. Cr(VI) did not affect the Fv/Fm ratio of chlorophyll fluorescence implying that the primary photochemical processes in photosystem 2 were not affected. However, the efficiency of excitation capture by open PS2 centres, in vivo quantum yield of PS2 photochemistry, and electron transport rate were significantly reduced by Cr(VI). The coefficient of photochemical quenching was reduced with a concomitant increase in coefficient of non-photochemical quenching, suggesting reduced demand for ATP and NADPH due to inhibition of CO2 assimilation. Lipid peroxidation was increased by Cr(VI) and the activities of superoxide dismutase and catalase (CAT) were increased. However, the CAT activity was reduced by high Cr(VI) concentration. The activities of ascorbate peroxidase and glutathione reductase were significantly reduced by Cr(VI) treatment.
In order to investigate the effects of low irradiation (LI) on cucumber (Cucumis sativus L. cv. Jinyou 35) during a ripening stage, our experiment was carried out in a climate chamber. Two levels of PAR were set for plants: normal irradiation [NI, 600 μmol(photon) m-2 s-1] and low irradiation [LI, 100 μmol(photon) m-2 s-1], respectively. The experiments lasted for 9 d; then both groups of plants were transferred under NI to recover for 16 d. The plants showed severe chlorosis after the LI treatment. Chlorophyll (Chl) a, initial slope, photosynthetic rate at saturating irradiation (P max), light saturation point, maximal photochemical efficiency of PSII (Fv/Fm), electron transport rate of PSII (ETR), soluble protein content, and catalase (CAT) activity in cucumber leaves decreased under LI stress, while Chl b, carotenoids, light compensation point, nonphotochemical quenching (qN), superoxide dismutase (SOD), and malondialdehyde (MDA) exhibited an increasing trend under LI. After 16 d of recovery, values of P max, Fv/Fm, ETR, qN, SOD, CAT, MDA, and soluble protein were close to those of the control after one, three, and five days of the LI treatment, while those kept under LI for 7 and 9 d could not return to the control level. Therefore, 7 d of LI stress was a meteorological disaster index for LI in cucumber at the fruit stage., Z. Q. Yang, C. H. Yuan, W. Han, Y. X. Li, F. Xiao., and Obsahuje seznam literatury
The effects of simulated acid rain on gas exchange, chlorophyll fluorescence, and anti-oxidative enzyme activity in cucumber seedlings (Cucumis sativus L. cv. Jingchun No. 4) were investigated. Acid rain significantly reduced net photosynthetic rate and mainly non-stomatal factors contributed to the decrease of photosynthesis during the experimental period. The reduced photosynthesis was associated with a decreased maximal photochemical efficiency (Fv/Fm) and the average quantum yield of the photosystem 2 (PS2) reaction centres (ΦPS2). Meanwhile, acid rain significantly increased the activities of guaiacol peroxidase (GPX) and superoxide dismutase (SOD), but decreased the activity of catalase (CAT) together with an increased content of malonyldialdehyde (MDA), Hence the changes in photosynthesis in acid rain treatment might be a secondary effect of acidity damage probably due to lipid peroxidation of lipids and proteins in thylakoid membrane rather than direct effect on PS2 reaction centre. and Jing-Quan Yu, Su-Feng Ye, Li-Feng Huang.
In Leymus chinensis, mild water stress (soil moisture 60-65 % of field capacity) had no significant effects on nitrogen metabolism, photosynthesis, and chlorophyll fluorescence. Severe water stress (35-40 %) significantly decreased the activities of nitrate reductase, glutamine synthetase, and glutamate dehydrogenase, net photosynthetic rate, stomatal conductance, transpiration rate, maximal efficiency of photosystem 2 photochemistry (Fv/Fm), actual quantum yield, and photochemical quenching, but increased the endopeptidase activity and malondialdehyde contents. The adverse effects on photosynthesis and N metabolism were markedly greater in reproductive shoots than in vegetative shoots. and Z. Z. Xu, G. S. Zhou.
The effect of low (1 mg/animal/day), medium (10 mg/animal/day) and high (100 mg/animal/day) intake of ascorbic acid on tissue lipid peroxidation (LPO) and the physical state of erythrocyte membranes was investigated in female guinea-pigs fed a vitamin E low diet. Animals were killed after 9-11 weeks and the blood, liver, lungs, kidneys and adrenals were analysed. The LPO was estimated by the determination of malondialdehyde with HPLC. The physical state of erythrocyte membranes was determined spectrofluorometrically and expressed as fluorescence polarization of membrane lipid specific probe 1,6-diphenyl-1,3,5-hexatriene. The LPO concentrations in the liver and adrenals of the group on a low vitamin C intake were significantly increased. A significant non-linear negative correlation between C vitamin levels and LPO concentrations was found in these tissues. The fluidity of erythrocyte membranes as a measure of their structural state was significantly lower in the group with a low intake of C vitamin. It is probable that the water-soluble antioxidants, such as vitamin C, act in the plasma as primary defense against oxidative stress if the radicals are formed initially in the aqueous phase of whole blood.
The effects of foliar spraying of the dithiocarbamate zineb on two cultivars of tomato grown in the field in a site with high ozone concentrations were studied by means of biomass assessment, antioxidant enzyme assays, lipid peroxidation, and chlorophyll fluorescence measurements. Zineb prevented the peroxidation of membrane lipids and decreased the activity of scavenging enzymes, which suggests that plants sprayed with zineb are subjected to lower oxidative stress than controls. The beneficial effects of zineb protection is the utilization of a larger fraction of absorbed radiant energy in photosynthesis and a larger fruit yield in plants of both cultivars. and Á. Calatayud, E. Barreno.
Fusilade (fluazifop-p-butyl) is one of the herbicides that inhibit acetyl-CoA carboxylase. The exogenous effect of 30, 60, and 90 ppm fusilade on peanut (Arachis hypogaea L. cv. Giza 5) leaves was studied. With increasing fusilade concentration, the peanut leaf chlorosis appeared after 7-10 d. Declined leaf pigment contents confirmed the leaf chlorosis. Electron microscopic observation of the fusilade-treated (FT) leaves revealed disorganization in the ultrastructure of mesophyll cell chloroplasts. An increase of plastoglobuli occurrence within chloroplasts and degenerated grana thylakoids were observed in FT leaves. Fusilade treatments induced mainly the enhancement of malondialdehyde content and the activities of peroxidases (guaiacol and ascorbate). On contrary, a decrease in H2O2 content, catalase and superoxide dismutase activities was recorded. Enhancements of the guaiacol and ascorbate peroxidase activities were associated with the decreasing H2O2 content in the FT leaves. Hydrogen peroxide seems not to be involved in the oxidative stress of FT leaves. In the FT leaves, the oxidative stress confirmed by chlorophyll degradation and lipid peroxidation might be caused by the other reactive oxygen species probably due to the decrease of superoxide dismutase activity., K. A. Fayez, D. E. M. Radwan, A. K. Mohamed, A. M. Abdelrahman., and Obsahuje bibliografii