Presence Of Excess NaCl Research Articles

Hydrogen Sulfide Modulates Salinity Stress in Common Bean Plants by Maintaining Osmolytes and Regulating Nitric Oxide Levels and Antioxidant Enzyme Expression

The purpose of the present study is to investigate the role of hydrogen sulfide (H2S), in improving resistance to common bean salt stress. Method shows that common bean seeds were soaked in water and in two concentrations of sodium hydrosulfide (50 and 100 µM) for 8 h. After 25 days from sowing, the pots were irrigated with water and with two concentrations of NaCl (75 and 150 mM) until the end of the experiment. Results revealed that H2S relieved salt stress by decreasing growth inhibition and photosynthetic characteristics, and increasing osmolyte contents (proline and glycine betaine). Furthermore, H2S reduced oxidative damage by lowering lipid peroxidation, electrolyte leakage, and reactive oxygen species production such as hydrogen peroxide, hydroxyl radicals, and superoxide anion by increasing non-enzymatic antioxidants such as ascorbic acid and glutathione, as well as enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), glutathione reductase (GR), and nitrate reductase (NR). Meanwhile, salt stress and H2S application increased the endogenous level of H2S, which was accompanied by an increase in nitric oxide concentration. H2S, in particular, maintained sodium (Na+) and potassium (K+) homeostasis in the presence of excess NaCl. In general, H2S effectively reduced oxidative stress in common bean plants by increasing relative expression levels of copper-zinc superoxide dismutase (Cu-ZnSOD), CAT, and glutathione S-transferase (GST). Applying H2S to common bean plants could protect them from salinity stress by maintaining the Na+/K+ balance, boosting endogenous H2S and nitric oxide levels, and preventing oxidative damage by increasing antioxidant activity.

Exogenous melatonin-mediated regulation of K+ /Na+ transport, H+ -ATPase activity and enzymatic antioxidative defence operate through endogenous hydrogen sulphide signalling in NaCl-stressed tomato seedling roots.

Melatonin (Mel) and hydrogen sulphide (H2 S) have emerged as potential regulators of plant metabolism during abiotic stress. Presence of excess NaCl in the soil is one of the main causes of reduced crop productivity worldwide. The present investigation examines the role of exogenous Mel and endogenous H2 S in tomato seedlings grown under NaCl stress. Effect of 30µm Mel on endogenous synthesis of H2 S was examined in roots of NaCl-stressed (200mm) tomato seedlings. Also, the impact of treatments on the oxidative stress markers, transport of K+ and Na+ , and activity of H+ -ATPase and antioxidant enzymes was assessed. Results show that NaCl-stressed seedlings supplemented with 30µm Mel had increased levels of endogenous H2 S through enhanced L-cysteine desulfhydrase activity. Mel in association with H2 S overcame the deleterious effect of NaCl and induced retention of K+ that maintained a higher K+ /Na+ ratio. Use of plasma membrane inhibitors and an H2 S scavenger revealed that Mel-induced regulation of K+ /Na+ homeostasis in NaCl-stressed seedling roots operates through endogenous H2 S signalling. Synergistic effects of Mel and H2 S also reduced the generation of ROS and oxidative destruction through the enhanced activity of antioxidant enzymes. Thus, it is suggested that the protective function of Mel against NaCl stress operates through an endogenous H2 S-dependent pathway, wherein H+ -ATPase-energized secondary active transport regulates K+ /Na+ homeostasis.

Salt Cluster Attachment to Crown Ether Decorated Phthalocyanines in the Gas Phase.

Crown ether decorated phthalocyanines were designed to form rigidly eclipsed aggregates with metal ions being sandwiched between the molecules. We studied tetra-[18]crown-6 ether functionalized zinc phthalocyanine (ZnPcTetCr) in the presence of excess NaCl by electrospray ionization mass spectrometry. ZnPcTetCr was found to form aggregates in the gas phase to which several neutral NaCl molecules are attached. Collision-induced dissociation experiments revealed that the ions observed in the positive- and negative-ion modes possess remarkably different structures. Their fragmentation behavior indicates that the sodium ions providing the charge of the positively charged aggregates are strongly bound inside the crown ether moieties, while the neutral salt units are less strongly attached. However, in the negatively charged ions, none of the sodium ions is embedded in the crown ether moieties, and the NaCl molecules were found to be attached as one large, weakly bound cluster.

Solid transformation of zeolite NaA to sodalite

Sodalite was successfully synthesized by solid-state transformation of NaA in the presence of excess NaCl. The transformation conditions, effect of cation exchange, and treatment agents were investigated. The transformation mechanism is proposed as zeolite A → carnegieite → sodalite. When the temperature is above a threshold value, the transformation is abruptly accelerated. K- and Cs-exchanged zeolite A are transformed more rapidly than NaA. Sodalite could not be formed when the NaA was treated with KCl.

Determination of cavitation bubble lifetimes using bubble-bubble coalescence data

The effect that surface-active solutes, such as aliphatic alcohols and sodium dodecylsulfate, have on the extent of bubble coalescence in liquids under different sonication conditions has been investigated by measuring the volume change of the solution following a period of sonication. The data obtained led to the conclusion that SDS does not reach equilibrium adsorption level at the bubble/solution interface. On this basis, a method is proposed for estimating nonequilibrium surface excess values for solutes that do not fully equilibrate with the bubble/solution interface during sonication. For the case of SDS in the presence of excess NaCl, the method was further employed to estimate the maximum lifetime of bubbles in a multibubble field. Data obtained from this study suggests that an acoustic bubble in a multibubble field has a finite lifetime, and that this lifetime decreases with increasing applied frequency, ranging from up to 0.35 ± 0.05 ms for 213 kHz to 0.10 ± 0.05 ms for 1062 kHz. These estimated lifetimes equate to a bubble in a multibubble field undergoing an upper limit of 50-200 oscillations over its lifetime for applied acoustic frequencies between 200 kHz and 1 MHz.

Study of the Coalescence of Acoustic Bubbles as a Function of Frequency, Power, and Water-Soluble Additives

The effect that surface-active solutes, such as aliphatic alcohols and sodium dodecyl sulfate (SDS), have on the extent of bubble coalescence in liquids under different sonication conditions has been investigated by measuring the volume change of the solution following a period of sonication. In general, the adsorption of surface-active solutes onto the bubble surface retards bubble coalescence. Within the limitations of the measurement method and the systems studied, bubble coalescence does not appear to be dependent on the applied acoustic power. Also, varying the applied acoustic frequency has a minimal effect on the extent of bubble coalescence in systems where long-range electrostatic repulsion between bubbles, imparted by the adsorbed surface-active solutes, dominates. However, when short-range steric repulsion (or other short-range repulsive forces) is the primary factor in inhibiting bubble coalescence, the dependence on the applied acoustic frequency becomes apparent, with less coalescence inhibition at higher frequencies. It is also concluded that SDS does not reach an equilibrium adsorption level at the bubble/solution interface under the sonication conditions used. On the basis of this conclusion, a method is proposed for estimating nonequilibrium surface excess values for solutes that do not fully equilibrate with the bubble/solution interface during sonication. For the case of SDS in the presence of excess NaCl, the method was further employed to estimate the maximum lifetime of bubbles in a multibubble field. It was concluded that an acoustic bubble in a multibubble field has a finite lifetime, and that this lifetime decreases with increasing applied frequency, ranging from up to 0.35 +/- 0.05 ms for 213 kHz to 0.10 +/- 0.05 ms for 1062 kHz. These estimated lifetimes equate to a bubble in a multibubble field undergoing an upper limit of 50-200 oscillations over its lifetime for applied ultrasound frequencies between 200 kHz and 1 MHz.

Mixed adsorption and surface tension prediction of nonideal ternary surfactant systems

To deal with the mixed adsorption of nonideal ternary surfactant systems, the regular solution approximation for nonideal binary surfactant systems is extended and a pseudo-binary system treatment is also proposed. With both treatments, the compositions of the mixed monolayer and the solution concentrations required to produce given surface tensions can be predicted based only on the γ-LogC curves of individual surfactants and the pair interaction parameters. Conversely, the surface tensions of solutions with different bulk compositions can be predicted by the surface tension equations for mixed surfactant systems. Two ternary systems: SDS/Hyamine 1622/AEO7, composed of homogeneous surfactants, and AES/DPCl/AEO9, composed of commercial surfactants, in the presence of excess NaCl, are examined for the applicability of the two treatments. The results show that, in general, the pseudo-binary system treatment gives better prediction than the extended regular solution approximation, and the applicability of the latter to typical anionic/cationic/nonionic nonideal ternary surfactant systems seems to depend on the combined interaction parameter, \( {\mathop {(\beta }\nolimits_{an}^s } + {\mathop \beta \nolimits_{cn}^s })/2 - {\mathop \beta \nolimits_{ac}^s }/4 \): the more it deviates from zero, the larger the prediction difference. If \( {\mathop {(\beta }\nolimits_{an}^s } + {\mathop \beta \nolimits_{cn}^s })/2 - {\mathop \beta \nolimits_{ac}^s }/4 \)→0, good agreements between predicted and experimental results can be obtained and both treatments, though differently derived, are interrelated and tend to be equivalent.

Tolerance of Grasses to Calcium Chloride, Magnesium Chloride and Sodium Chloride

The tolerance of six cool-season grasses and six warm-season grasses to three kinds of salt was examined in solution culture. Among the cool-season grasses, tall fescue (Festuca arundinacea Schreb.) was the most tolerant to all three salts. Among the warm-season grasses, bermudagrass (Cynodon dactylon (L.) Pers.) was the most tolerant to excess calcium chloride and sodium chloride, while bahiagrass (Paspalum notatum Flugge) was the most tolerant to excess magnesium chloride. A positive and significant correlation was found between estimates of the concentration at which plant growth decreases by 50% (C50) in the presence of excess CaCl2 and those in the presence of excess NaCl. The C50 estimates in excess MgCl2, however, were not correlated with those in the other two salts. The results suggest that common physiological mechanism confers tolerance to both excess CaCl2 and excess NaCl, but a different mechanism to excess MgCl2.

Transcriptional regulation of the Antifungal Protein in Aspergillus giganteus.

Regulation of the expression of the afp gene that codes for the Antifungal Protein of Aspergillus giganteus was investigated using a reporter system. For this purpose, the E. coli reporter gene uidA encoding beta-glucuronidase (GUS) was placed under the control of the afp promoter. No homologous integration of the reporter construct into the afp site was observed among 156 transformants tested. In one of the transformants carrying a single, ectopically integrated, copy of the construct, GUS and AFP both displayed exactly the same temporal expression patterns under various cultivation conditions, as assayed by Northern and protein analyses. Thus, this transformant was used to identify factors that are involved in the transcriptional regulation of afp expression. Expression is only detectable in the vegetative mycelium, whereas no expression occurs in aerial hyphae or conidia, indicating that afp expression is developmentally regulated. Transcription of afp is regulated by ambient pH, being suppressed under acidic conditions and strongly induced under alkaline conditions. This observation suggests that PacC regulates the afp gene, which is consistent with the presence of two putative PacC binding sites within the 5' upstream region. Transcription is not subject to carbon catabolite repression or nitrogen metabolite repression. The expression of afp is up-regulated by heat shock, upon growth in the presence of excess NaCl and ethanol, and under conditions of carbon starvation. In contrast, expression decreases slightly in the presence of hydrogen peroxide and under nitrogen starvation. These data are compatible with the presence of a putative heat shock element (NTTCNNGANTTCN) and five putative C(4)T stress-responsive elements within the afp promoter.

A review of recent studies of the role of zinc as an inhibitor of hot corrosion from molten sulphates

Hot corrosion of metals in the temperature range 700–900°C is caused by the presence of sulphate deposits on the surface formed from the reaction between sea salt and sulphur trioxide in marine turbine engines. This paper reviews investigations of the effects of adding zinc in order to inhibit this form of corrosion. The presence of zinc in the salt deposits served to modify the rate of hot corrosion significantly. Its role has been studied with respect to the acid-base fluxing theory and in the presence of excess NaCl. The zinc reduced the ability of the corrosive salt mixtures to dissolve the protective oxide layers on the alloys and also lowered the electrochemical potential of the corrosion reaction itself.

Studies on the sodium chloride injury of vegetable crops in relation to the form of nitrogen in sand culture. II

Spinach, Chinese cabbage, celery, turnip, and carrot were grown in sand culture under glass and were supplied with NO3 (a mixture of nitrates of K, Ca, and Mg), NH4+NO3 (ammonium nitrate), or NH4 (ammonium sulfate) in the absence and presence of NaCl, to study the sodium chloride injury of these crops in relation to the form of nitrogen supplied. The nitrogen concentration of any nutrient solution was equally 10m.e./l (140ppm), and the concentration of NaCl added to the solution was 8000ppm for spinach and Chinese cabbage, 6000ppm for celery, 2500ppm for turnip, and 4000 ppm for carrot. The pH of the solutions was adjusted to 6.2-6.4 in all cases.1. Both in the absence and presence of NaCl, plant growth was much better with NO3 than with NH4. And NH4+NO3 plants showed growth similar to or less than that shown by NO3 plants. Effect of NaCl on the yield of crops was not always constant with each nitrogen form.2. The dry weight percentage of plants generally incresed with the increasing supply of NH4-N.3. In the absence of NaCl, plants supplied with NO3 developed no specific symptoms; but NH4+NO3 plants produced darker green foliage than NO3 plants in some crops, and produced uneven or leathery leaves in Chinese cabbage. The supply of NH4 alone generally caused various specific symptoms, such as entire or interveinal chlorosis, burn, or withering of leaves. The rate of dead leaves increased as the amount of NH4-N increased. Some crops supplied with NH4 alone had brownish or purplish rootlets.In the presence of NaCl, the supply of NH4-N crops caused serious symptoms of malnutrition more markedly than in the absence of NaCl with NH4 alone chlorosis was developed markedly in general, and leaves of some crops were fragile. In Chinese cabbage, NH4+NO3 caused marginal rot of younger leaves, symptom of Ca deficiency, more markedly than NO3; and plants supplied with NH4 alone were severely stunted in growth showing entire chlorosis, marginal rot, and burn of leaves. In carrot, branched roots occurred to a high degree with NH4+NO3 or NH4.4. In the absence of NaCl, as the proportion fo NH4-N in the solution increased, N content of both leaves and roots tended to increase; and P content of leaves similarly increased, while that of roots showed an irregular tendency. Content of K, Ca, or Mg of both leaves and roots generally decreased with the increasing supply of NH4-N.In the presence of NaCl, similar tendencies as mentioned above were obtained for each element, except for N in leaves which mostly decreased with the supply of NH4-N, and the content of any essential cation was generally depressed by the interaction with Na. Moreover, Cl or Na content of leaves increased with the increasing supply of NH4-N, while that of roots showed a variable tendency with crop species.5. It is concluded that NO3-N is much more favourable than NH4-N as the nitrogen source for the crops tested, especially in the presence of excess NaCl. Application of NH4-N in the presence of excess NaCl may cause marked interference in absorption of essential cations, especially of Ca, and increased accumlation of Cl or Na in leaves.

Studies on the sodium chloride injury of vegetable crops in relation to the form of nitrogen supplied and the calcium nutrition in sand culture

Spinach and Chinese cabbage were grown in sand culture under glass and were supplied with NO3 (10m.e./l) or NH4+NO3 (5+5m.e./l) and with various Ca levels, both in the absence and presence of excess NaCl (100 millimol). The Ca levels used were: (a) 5m.e./l, (b) 5m.e./l plus foliar sprays (0.04M CaCl2, twice a week), and (c) 15 m.e./l, with CaCl2 being used as the Ca source. All of the solutions were adjusted to pH 6.2_??_6.4.1. In spinach, when no NaCl was added, it was observed that the favourable Ca level in the nutrient solution was higher with NH4+NO3 than with NO3 alone, and Ca sprays had a slight effect to increase the yield when nitrogen was supplied as NH4+NO3. In the presence of excess NaCl, however, both increasing concentration of Ca in the nutrient solution and Ca sprays were not effective and rather caused slight reduction of yield irrespective of the form of nitrogen supplied, and NO3 gave higher yields than NH4+NO3.In Chinese cabbage, the application of NH4-N and excess NaCl caused increased prevalence and severity of marginal rot on younger leaves, a symptom of calcium deficiency, which had detrimental effects on heading, yield and quality. To prevent the occurrence of this disorder, Ca sprays into the heart were remarkably effective in any case, but the increasing concentration of Ca in the nutrient solution had scaresely any effect.2. Contents of Ca, K or Mg in leaves were in antagonistic relations with Na or NH4. In spinach, Ca sprays or increasing concentration of Ca in the nutrient solution resulted in increased Ca content of leaves. In Chinese cabbage, however, Ca content of leaf blades of inner leaves was remarkably lower and less influenced by the treatments than that of outer leaves, and Ca sprays significantly increased the Ca content of leaf blades, while the increasing concentration of Ca in the nutrient solution had effect to increase Ca content of leaf blades only of outer leaves and rather decreased that of head leaves. And it was recognized that the Ca content or the Ca/N equivalent ratio in leaf blades of Chinese cabbage was closely related to the occurrence of the marginal rot.