Inhibitory Effect Of Salt Research Articles

The Effects of Green Tea Leaf Extract on Cytogenetical and Physiological Parameters of Allium cepa L. exposed to Salinity

The aim of this study investigated the effects of 50 mg L-1 green tea leaf extract in decreasing harmful effects of 0.175 M salinity stress on the mitotic activity, chromosomal aberrations, seedling growth (fresh weight, radicle length and radicle number), micronucleus frequency which is the simplest indicator, the most effective of cytological damage and bulb germination of A. cepa L. In only green tea leaf extract medium, the radicle length and radicle number of bulbs were partially reduced compared to the control bulbs germinated in the distilled water medium. While their germination percentage and fresh weight statistically indicated the same values. Besides, the mitotic index and chromosomal abnormalities in the root tip meristematic cells of Allium cepa bulbs germinated in alone green tea leaf extract medium increased compared to germinated control bulbs in the distilled water medium, whereas the micronucleus frequency showed statistically the same value compared to the control. In other words, it can be said that salt stress significantly inhibited the seedling growth and bulb germination of Allium cepa. What’s more, it significantly reduced the mitotic index in the root tip meristems of the bulbs and increased the number of chromosomal abnormalities and micronuclues frequency. On the other hand, inhibitory effects of salt on the mitotic activity, seedling growth, bulb germination, chromosomal abnormalities and micronuclues frequency significantly decreased with the application of green tea leaf extract. The germination percentage, radicle lenght, radicle number, fresh weight, mitotic index, micronuclues frequency and chromosomal aberrations of the seedlings grown in 0.175 M salinity were 23 %, 10.3 mm, 12.7, 7 g, 1.2 %, 13 % and 17 % respectively, while these values became 75 %, 13.4 mm, 17.2, 13.8 g, 6.3 %, 9 % and 9.3 % in the seedlings treated with 50 mg L-1 green tea leaf extract.

Numerical modeling of methane hydrate accumulation with mixed sources in marine sediments: Case study of Shenhu Area, South China Sea

The natural gas hydrates detected in Shenhu Area, South China Sea are considered to have great potential for exploitation and to become a research hotspot. However, details of the dynamic accumulation and evolution processes of gas hydrate over a long time in this area remain unclear. In this study, we developed a numerical model to predict the accumulation of gas hydrates in the marine sediments by introducing the biogenic methanogenesis module to the framework of the existing simulator TOUGH+HYDRATE. A one-dimensional dynamic model was applied to reproduce the formation of gas hydrate at site SH2 in Shenhu Area. The burial of sediments and associated phenomena (e.g., evolution of temperature, sediment compaction and consequent reduction in sediment porosity and permeability, fluid expulsion) are taken into account. Modeling results indicate that with the conventional conversion coefficient (CC) of organic carbon to methane of 0.15, the amount of in-situ biogenic methane is not sufficient to form the highly saturated hydrate detected at this location and the remaining methane (91.4%) is supplied by the upward flow of fluids. The tectonic movement that took place about 1.5 Ma created pathways for the fluids to migrate vertically. The pore water and methane gas fluxes in the upward fluids were determined as 2 × 10−10 kg/s·m2 and 1 × 10−11 kg/s·m2, respectively, using the proved hydrate saturation profile and measured pore water chlorinity from recovered core samples. The distribution of hydrate in the sediments is significantly influenced by pore water salinity. The inhibitory effect of salt on hydrate formation, which shifts the pressure of three-phase (i.e., solid hydrate, methane gas and pore water) equilibrium to actual pore water pressure, could be the major reason for the appearance of a three-phase co-existence zone in the hydrate concentrated zone. Additionally, the water flux and diffusivity of salt have a profound effect on the formation of gas hydrate by affecting the salinity of pore water in the gas hydrate concentrated zone. The results of this study are of great significance for guiding marine gas hydrate exploration and resource evaluation.

Growth Response to Ionic and Osmotic Stress of NaCl in Salt‐tolerant and Salt‐sensitive Maize

Salt-tolerant maize (STM) and salt-sensitive maize (SSM) were treated with 100 mM NaCl for 1, 3 and 6 d and the contents of Na+ and Cl(-) (cps) of different organelles of leaf cells determined by X-ray microanalysis. The results showed that Na+ and Cl(-) entered the cytoplasm, vacuole, chloroplast and apoplast simultaneously. When STM and SSM were treated in 100 mM NaCl at atmospheric pressure (-P) and with pressure equivalent to the osmotic pressure of the NaCl (+P), the dry weights of STM (+P) and SSM (+P) plants were greater than that of STM (-P) and SSM (-P) plants, showing that the inhibitory effect of salt on plant growth was at least partially due to the osmotic effect of the NaCl. When STM and SSM were treated with NaCl and iso-osmotic polyethlene glycol, the dry weights of plants given the iso-osmotic polyethlene glycol treatment were lower for both maize lines than that of the NaCl-treated plants. Our data show that under NaCl stress, both STM and SSM seedlings simultaneously suffered from osmotic and ion stresses.

Nitrate reductase in durum wheat seedlings as affected by nitrate nutrition and salinity.

The combined effects of nitrate (0, 0.1, 1, 10 mm) and salt (0, 100 mm NaCl) on nitrogen metabolism in durum wheat seedlings were investigated by analysis of nitrate reductase (NR) expression and activity, and metabolite content. High salinity (100 mm NaCl) reduced shoot growth more than root growth. The effect was independent of nitrate concentration. NR mRNA was present at a low level in both leaves and roots of plants grown in a nitrogen-free medium. NaCl increased NR mRNA at low nitrate, suggesting that chloride can mimic nitrate as a signal molecule to induce transcription in both roots and leaves. However, the level of NR protein remained low in salt-stressed plants, indicating an inhibitory effect of salt on translation of NR mRNA or an increase in protein degradation. The lower activity of nitrate reductase in leaves of high-nitrate treated plants under salinity suggested a restriction of NO3- transport to the shoot under salinity. Salt treatment promoted photorespiration, inhibiting carbohydrate accumulation in plants grown on low nitrate media. Under salinity free amino acids, in particular proline and asparagine, and glycine betaine could function as osmolytes to balance water potential within the cell, especially when nitrogen availability exceeded the need for growth.

Effects of salts on the conformation and catalytic properties of d-amino acid aminotransferase.

The effects of salts on the biochemical properties of D-amino acid aminotransferase from Bacillus sp. YM-1 have been studied to elucidate both the inhibitory effects of salts on the activity and the protective effects of salts on the substrate-induced inactivation. The results from UV-visible spectroscopy studies on the reaction of the enzyme with D-serine revealed that salt significantly reduced the rate of the formation of the quinonoid intermediate and its accumulation. The kinetic and spectroscopy studies of the reaction with alpha-[(2)H]-DL-serine in different concentrations of NaCl provided evidence that the rate-limiting step was changed from the deprotonation of the external aldimine to another step(s), presumably to the hydrolysis of the ketimine. Gel filtration chromatography data in the presence of NaCl showed that the enzyme volume was reduced sharply with the increasing NaCl concentration, up to 100 mM. An additional increase of the NaCl concentration did not affect the elution volume, which suggests that the enzyme has a limited number of salt-binding groups. These results provide detailed mechanistic evidence for the way salts inhibit the catalytic activity of Damino acid aminotransferase

Effect of high salinity on tracheary element differentiation in light-grown callus of Mesembryanthemum crystallinum

This study investigated the inhibitory effects of NaCl on tracheary element (TE) differentiation in light-grown callus of ice plant Mesembryanthemum crystallinum L., a halophyte which adaptes well to saline environments. When ice plant callus was grown in a modified Linsmaier-Bednar and Skoog culture medium containing no NaCl (control medium), up to 20% of ice plant cells differentiated into tracheary elements during in vitro culture. Close examination of callus tissues stained with potassium permanganate revealed that tracheary elements were aggregated as discrete nodules. Some strikingly elongated tracheary elements were found in the macerated tissues. Experimental results indicated that adding 200 mM NaCl to the control medium reversibly inhibited the formation of tracheary element in the halophytic cells. The rate of tracheary element formation increased accordingly as the rate of cell growth in control medium. In the presence of high salt, the degree of tracheary element differentation remained low through the growth cycle. The inhibitory effect of salt on tracheary element differentiation was overcome by adding 10 mg l−1 salicylic acid, a known signaling compound that induces a diverse group of defense-related genes, including genes involved in reinforcing the host cell wall. Furthermore, microscopic examination revealed that most tracheary elements formed under this treatment (200 mM NaCl plus 10 mg l−1 salicylic acid) were round shaped. The results suggest that high salt inhibits both the biosynthesis of secondary wall components and cell elongation ice plant in vitro culture.

Effect of different salts of sodium and potassium on the growth of Atriplex prostrata (Chenopodiaceae)

Although there are a variety of ions occurring in the soil throughout most of North America, the majority of halophyte literature focuses on the effects of NaCl on plants. In this study, a comparison is made of the effects of NaCl, KC1, Na2SO4, and K2SO4, on growth of the halophyte Atriplex prostrata Boucher ex DC (SYN: A. triangularis Willd.) at 0, ‐0.75, ‐1.00, and ‐1.50 MPa. Plant survival, height, number of leaves, nodes, and branches were recorded weekly. Photosynthesis was measured once before plants were harvested and dry mass was determined after one month. Content of Na+, K+,‐Mg2+, and Cl‐ in plant tissue was also measured. A general trend observed was that all plant growth parameters decreased with a lowering of the medium osmotic potential, and that K+ salts were more inhibitory than Na+ salts. Ion content of plant tissue generally increased with a lowering of osmotic potential. Our data indicated that K+, a plant macronutrient, was more inhibitory to plant growth than Na+. It is possible that halophytes such as Atriplex prostrata could use Na+ as an osmoticum to adjust the vacuolar water potential, but were unable to use K+ for this function because of a specific ion toxicity. The inhibitory effect of salt on plant growth parameters and survival follow the pattern; K2SO4 >KCl>Na2SO4=NaCl.

Response of three arid zone grasses to salt and waterlogging

In most arid and semiarid regions, the combination of salinity and waterlogging is a dual problem. The combined effects of excess salt and oxygen shortage are potentially highly damaging. In order to assess whether toxic effects of salts are exacerbated under oxygen‐deficient conditions, 8‐week‐old plants of 3 arid zone grass species, Leptochloa fusca (L.) Kunth., Cynodon dactylon (L.) Pers., and Panicum turgidum Forssk., were exposed to NaCl, waterlogging, or NaCl + waterlogging for 5 weeks in greenhouse conditions. There were no significant effects of these stresses on the biomass production of L. fusca, whereas an inhibitory effect of salt and of salt + waterlogging was observed on C. dactylon. The growth of P. turgidum was severely inhibited by all three stresses. A marked inhibitory effect of the combination of salinity + waterlogging was observed on P. turgidum and also on C. dactylon. Leptochloa fusca accumulated significantly higher amounts of Na+, Cl−, K+, and Ca2+ in its shoots compared with the...

Influence of salt, pH and temperature on Staphylococcus aureus MF-31 catalase

Catalase (EC 1.11.1.6) from Staphylococcus aureus MF-31 was isolated. The purification procedure included ethanol-chloroform precipitation, ammonium sulfate fractionation, ultrafiltration and Sephadex G-200 column chromatography. The apparent native molecular weight was 235000 ± 5000. The enzyme was composed of four subunits, each having a molecular weight of 64 000 ± 1000. The purified enzyme had an apparent isoelectric point of 5·3 ± 0·1 pH units. The effects of salt, salt concentration, pH and temperature were examined for their influence on catalase stability. The enzyme was stable over the pH range of 4–9, and was inactivated at temperatures above 60°C. The inhibitory effects of salt were: NaCl > MgCl 2 > KCI. The combination of NaCl and low pH was the most inhibitory.

Microbial spoilage of luncheon meat prepared in an impermeable plastic casing

Freshly cooked luncheon meat in a plastic (PVDC) casing had an aerobic plate count of about 102/g. The flora was composed of approximately equal numbers of Bacillus and Micrococcus spp. Storage at 10°C for 42 d produced little increase in bacterial numbers, or changes in pH value or glucose content at either the surface or core of the luncheon meat. Storage at 25°C allowed Bacillus spp. to proliferate at the surface. The inhibitory effect of salt and nitrite on the growth of heated Bacillus spores at low redox potentials probably accounts for the absence of growth within the product. Growth at the surface was accompanied by a fall in pH (6.8 to 6.2) and an increase in glucose (1.6 to 3.6 mg/g) and L(+)‐lactic acid (1.2 to 2.3 mg/g). By day 14 the Bacillus spp. had been displaced by a Streptococcus sp. (107/g) which remained the dominant organism until the experiment ended on day 28. The pH continued to fall from 5.7 on day 14 to 5.2 on day 28, the L(+)‐lactic acid rose to 6.1 mg/g, but the glucose remained constant at the day 7 level (3.6 mg/g). This indicates that glucose converted to lactic acid was largely replaced by hydrolysis of the starch portion of the luncheon meat mediated by amylases produced by the Bacillus microflora. It appears that growth of the Streptococcus is dependent upon the denitrifying activities of the initial Bacillus flora reducing the concentration of nitrite ion to non‐inhibitory levels.

An Fc-receptor activity of plasma membranes from guinea-pig peritoneal polymorphonuclear leucocytes.

Plasma membranes prepared from guinea-pig peritoneal polymorphonuclear leucocytes showed an immune-complex-binding activity that corresponded well with the activity in intact cells. The characteristics of this activity were reversible binding, dependence on the Fc portion of antigen-complexed IgG (immunoglobulin G), competition with aggregated IgG and independence from energy metabolism. These results support the conclusion that the binding activity found in the isolated plasma membranes is an Fc-receptor activity of guinea-pig peritoneal polymorphonuclear leucocytes. The activity showed Kd = 6.7 x 10(-8) M-IgG and maximum binding of 17 pmol of IgG/mg of membrane protein when measured with an immune complex of alpha-amylase and homologous guinea-pig anti-(alpha-amylase) IgG. Inhibition of the Fc-receptor activity by a series of various salts indicated the contribution of the hydrophobic interaction to the binding. Inhibitory effects of salts or metal-chelating reagents on the Fc-receptor activity were also observed on superoxide generation by these cells induced by the immune complex, suggesting a role of the Fc receptor as the immune-complex-binding site responsible for the initiation of superoxide generation.

Inhibitory effects of salts on the nicotinamide adenine dinucleotide specific isocitrate dehydrogenase from Blastocladiella emersonii

The effect of different salts on the NAD-specific isocitrate dehydrogenase from Blastocladiella emersonii has been studied. The results show that the salt inhibition depends on the size of the anions and that the ionic strength is of minor importance. The salts inhibit the enzyme in a competitive manner with regard to isocitrate. The isocitrate concentration giving half saturation increased by the same factor whether or not the activator AMP was present. The finding that higher salt concentrations are needed to inhibit the enzyme in the presence of AMP is due to the fact that in this case isocitrate is more tightly bound. Stopped-flow experiments demonstrated that when the enzyme was incubated with isocitrate and metal ions prior to initiation of the reaction by addition of NAD, the salt inhibition needed several seconds to be fully expressed. Moreover, a lag occurred before NADH was formed when the enzyme was mixed with its substrates and cofactor. The data suggest that the hysteretic properties of the enzyme are due to isomerization of the enzyme molecules, and that specific binding sites are involved in the salt inhibition.