Salt-induced modulation in inorganic nutrients, antioxidant enzymes, proline content and seed oil composition in safflower (Carthamus tinctorius L.)

BACKGROUND: Safflower (Carthamus tinctorius L.) has gained considerable ground as a potential oil‐seed crop. However, its yield and oil production are adversely affected under saline conditions. The present study was conducted to appraise the influence of salt (NaCl) stress on yield, accumulation of different inorganic elements, free proline and activities of some key antioxidant enzymes in plant tissues as well as seed oil components in safflower. Two safflower accessions differing in salt tolerance (Safflower‐33 (salt sensitive) and Safflower‐39 (salt tolerant)) were grown under saline (150 mmol L^?1) conditions and salt‐induced changes in the earlier‐mentioned physiological attributes were determined. RESULTS: Salt stress enhanced leaf and root Na⁺, Cl^? and proline accumulation and activities of leaf superoxide dismutase, catalase and peroxidase, while it decreased K⁺, Ca²⁺ and K⁺/Ca²⁺ and Ca²⁺/Na⁺ ratios and seed yield, 100‐seed weight, number of seeds, as well as capitula, seed oil contents and oil palmitic acid. No significant effect of salt stress was observed on seed oil α‐tocopherols, stearic acid, oleic acid or linoleic acid contents. Of the two safflower lines, salt‐sensitive Safflower‐33 was higher in leaf and root Na⁺ and Cl^?, while Safflower‐39 was higher in leaf and root K⁺, K⁺/Ca²⁺ and Ca²⁺/Na⁺ and seed yield, 100‐seed weight, catalase activity, seed oil contents, seed oil α‐tocopherol and palmitic acid. Other attributes remained almost unaffected in both accessions. CONCLUSION: Overall, high salt tolerance of Safflower‐39 could be attributed to Na⁺ and Cl^? exclusion, high accumulation of K⁺ and free proline, enhanced CAT activity, seed oil α‐tocopherols and palmitic acid contents. Copyright © 2011 Society of Chemical Industry     

Transport of organic acid anions and guanosine into vacuoles of Saccharomyces pastorianus

Isolated vacuoles of the yeast Saccharomyces pastorianus accumulate citrate, α-ketoglutarate, malate and guanosine. This accumulation is Mg ATP-dependent and inhibited by protonophores. The ionophores monensin and A23187 (electroneutral Meⁿ⁺/nH⁺-exchange) inhibit guanosine accumulation but fail to block citrate uptake. Mg²⁺ ions (2 mM ) increase the values of both Δ$ \tilde \mu $H⁺ components and stimulate the uptake of all the above compounds. Ca²⁺ ions (1 mM ), hyperpolarizing the yeast vacuolar membrane and dissipating the pH gradient, inhibit guanosine uptake and stimulate that of citrate. It is concluded that guanosine is transported into yeast vacuoles by an H⁺/guanosine antiporter while citrate, malate and α-ketoglutarate are translocated by a uniporter(s) at the expense of the membrane potential (positive inside).     

Using L‐Arginine‐Functionalized Gold Nanorods for Visible Detection of Mercury(II) Ions

A rapid and simple approach for visible determination of mercury ions (Hg²⁺) in aqueous solutions was developed based on surface plasmon resonance phenomenon using L‐arginine‐functionalized gold nanorods (AuNRs). At pH greater than 9, the deprotonated amine group of L‐arginine on the AuNRs bound with Hg²⁺ leading to the side‐by‐side assembly of AuNRs, which was verified by transmission electron microscopy images. Thus, when Hg²⁺ was present in the test solution, a blue shift of the typical longitudinal plasmon band of the AuNRs was observed in the ultra violet‐visible‐near infrared (UV‐Vis‐NIR) spectra, along with a change in the color of the solution, which occurred within 5 min. After carefully optimizing the potential factors affecting the performance, the L‐arginine/AuNRs sensing system was found to be highly sensitive to Hg²⁺, with the limit of detection of 5 nM (S/N = 3); it is also very selective and free of interference from 10 other metal ions (Ba²⁺, Ca²⁺, Cd²⁺, Co²⁺, Cs⁺, Cu²⁺, K⁺, Li⁺, Ni²⁺, Pb²⁺). The result suggests that the L‐arginine‐functionalized AuNRs can potentially serve as a rapid, sensitive, and easy‐to‐use colorimetric biosensor useful for determining Hg²⁺ in food and environmental samples.     

Simultaneous determination of free calcium,magnesium, sodium and potassium ion concentrations in simulated milk ultrafiltrate and reconstituted skim milk using the Donnan Membrane Technique

This study focused on determination of free Ca²⁺, Mg²⁺, Na⁺ and K⁺ concentrations in a series of CaCl₂ solutions, simulated milk ultrafiltrate and reconstituted skim milk using a recently developed Donnan Membrane Technique (DMT). A calcium ion selective electrode was used to compare the DMT results. The study showed that the free Ca²⁺ concentrations measured by the DMT agreed well with calcium electrode data. Concentrations of free Ca²⁺, Mg²⁺, Na⁺ and K⁺ measured by the DMT agreed with concentrations predicted by existing ion speciation models. It is concluded that the DMT is suitable to measure various free metal ion concentrations simultaneously in complex milk-type systems.     

The role of K+ and H+ transport systems during glucose‐ and H2O2‐induced cell death in Saccharomyces cerevisiae

Glucose, in the absence of additional nutrients, induces programmed cell death in yeast. This phenomenon is independent of yeast metacaspase (Mca1/Yca1) and of calcineurin, requires ROS production and it is concomitant with loss of cellular K⁺ and vacuolar collapse. K⁺ is a key nutrient protecting the cells and this effect depends on the Trk1 uptake system and is associated with reduced ROS production. Mutants with decreased activity of plasma membrane H⁺‐ATPase are more tolerant to glucose‐induced cell death and exhibit less ROS production. A triple mutant ena1‐4 tok1 nha1, devoid of K⁺ efflux systems, is more tolerant to both glucose‐ and H₂O₂‐induced cell death. We hypothesize that ROS production, activated by glucose and H⁺‐ATPase and inhibited by K⁺ uptake, triggers leakage of K⁺, a process favoured by K⁺ efflux systems. Loss of cytosolic K⁺ probably causes osmotic lysis of vacuoles. The nature of the ROS‐producing system sensitive to K⁺ and H⁺ transport is unknown. Copyright © 2010 John Wiley & Sons, Ltd.     

Characterization of the respiration‐induced yeast mitochondrial permeability transition pore

When isolated mitochondria from the yeast Saccharomyces cerevisiae oxidize respiratory substrates in the absence of phosphate and ADP, the yeast mitochondrial unselective channel, also called the yeast permeability transition pore (yPTP), opens in the inner membrane, dissipating the electrochemical gradient. ATP also induces yPTP opening. yPTP opening allows mannitol transport into isolated mitochondria of laboratory yeast strains, but mannitol is not readily permeable through the yPTP in an industrial yeast strain, Yeast Foam. The presence of oligomycin, an inhibitor of ATP synthase, allowed for respiration‐induced mannitol permeability in mitochondria from this strain. Potassium (K⁺) had varied effects on the respiration‐induced yPTP, depending on the concentration of the respiratory substrate added. At low respiratory substrate concentrations K⁺ inhibited respiration‐induced yPTP opening, while at high substrate concentrations this effect diminished. However, at the high respiratory substrate concentrations, the presence of K⁺ partially prevented phosphate inhibition of yPTP opening. Phosphate was found to inhibit respiration‐induced yPTP opening by binding a site on the matrix space side of the inner membrane in addition to its known inhibitory effect of donating protons to the matrix space to prevent the pH change necessary for yPTP opening. The respiration‐induced yPTP was also inhibited by NAD, Mg²⁺, NH₄⁺ or the oxyanion vanadate polymerized to decavanadate. The results demonstrate similar effectors of the respiration‐induced yPTP as those previously described for the ATP‐induced yPTP and reconcile previous strain‐dependent differences in yPTP solute selectivity. Copyright © 2013 John Wiley & Sons, Ltd.     

KCI, CaCI2, Na+ Binding, and Salt Taste of Gum Systems

Aqueous nonionic (0.3% w/v) and ionic (0.1% and 0.3% w/v) gum systems containing NaCl, or equal weights of NaCl plus KCl, or NaCl plus CaCl, were examined. At equivalent molar concentrations of added ions, ²³Na NMR transverse relaxation rates (R₂, set^?1) showed an increase in average Na⁺ mobility with the addition of K⁺ or Ca²⁺ to ionic gum systems. Correspondingly, salt taste increased with addition of KCl as determined by Decision Boundary modeling of subject identification data. Viscosity did not affect saltiness. Na⁺ was free to induce salt taste when K⁺ was bound to the gum. Enhancement of salt taste by KCl is due, in part, to competitive binding of Na⁺ and K⁺ in a system.     

Effect of gamma irradiation and sodium hydroxide treatment on the debittering of olive (Olea europaea) fruits

The effect of gamma irradiation and sodium hydroxide (NaOH) treatment on the debittering of olive (Olea europaea, var Surrany) fruits was investigated. Fruits were treated with 1, 2 or 3 kGy of gamma irradiation at a dose rate of 669 Gy h^?1. Irradiated and unirradiated fruits were processed with NaOH solution (11 g l^?1) for 3 or 6 h and washed once per day for 3 days. The fruits were then immersed in brine (56 g l^?1 sodium chloride) and stored for 12 months at room temperature. Dissolved organic and inorganic solids, Na⁺, K⁺ and Ca²⁺ contents, pH and electrical conductivity values were determined in the debittering solutions (lye, rinse and washing waters) and brines. Gamma irradiation significantly (p < 0.05) increased the dissolved organic and inorganic solids and the Na⁺ and K⁺ concentrations in the debittering solutions when the fruits were treated with NaOH for 3 h. On the other hand, gamma irradiation had no significant effect on these parameters, except for an increase in K⁺ concentration, when using NaOH solution for 6 h. Gamma irradiation with NaOH treatment for 3 h decreased the concentration of Ca²⁺ in the debittering solutions, whereas irradiation and treatment with NaOH solution for 6 h increased its concentration. © 2003 Society of Chemical Industry     

Monitoring the effects of divalent ions (Mn and Ca) in heat-set whey protein gels

Exploring the effects of cations in whey protein-based gels (WPG) is of importance when these gels are used for controlled release applications in food systems. The objective of this study was to evaluate both water uptake and cation release from heat-set WPGs. Magnetic Resonance Imaging and NMR relaxometry were employed to study the uptake and release. A non-paramagnetic (Ca⁺²) and a paramagnetic cation (Mn⁺²) were incorporated into the WPG as model divalent cations. Cylindrical pieces of WPGs with manganese were immersed in water (pH 2.40, 7.00, 10.40) or in EDTA solution whereas WPGs with calcium were immersed in water at pH 2.40. Water uptake by the gels was influenced by both ionic environment and pH. The release of Mn⁺² from WPG was enhanced by the presence of EDTA. Relaxation spectra of Mn⁺²-loaded gels were significantly influenced by pH of the suspending fluid and by the presence of EDTA. Results of relaxometry experiments, obtained with Ca⁺²-loaded gels immersed in water at pH 2.40, indicated a strong correlation (R² > 0.99) between relative areas of the proton pools and the amount of calcium released to the medium. Results support the use of MRI and NMR to monitor cation release and water uptake in WPG, non-destructively.     

Thermodynamic approach to the selection of polyuronide sequestrants for preventive and medicinal nutrition

An approach to the analysis of isotherms of cooperative binding is developed that allows to calculate approximately affinity profiles, i.e. dependencies of binding constants on binding densities. The comparison of the affinity profiles of the interactions of Ca²⁺ and Sr²⁺ ions with sodium pectate as well as sodium alginates with the different content of the blocks of α-L-guluronic acid residues (GG-blocks) and blocks of mixed composition showed that (1) pectate has higher affinity to both ions as compared with alginates; (2) the affinity of pectate to Ca²⁺ ions is comparable to its affinity to Sr²⁺ ions but in the case of Ca²⁺ ions the maximum of the affinity profile falls on the substantially lesser value of the binding density in comparison to Sr²⁺ ions that seems to be unfavorable from the standpoint of the use of this polyuronide in preventive or medicinal nutrition; (3) the affinity of both alginates to Sr²⁺ ions at relatively low binding densities exceeds their affinity to Ca²⁺ ions; (4) the affinity of alginates to Sr²⁺ ions increases with the increase in the content of GG-blocks, whereas the affinity to Ca^2- ions practically does not depend on the composition of the alginate; (5) the maximum binding density of Sr²⁺ ions to the alginates approximately corresponds to the content of GG-blocks. These results corroborate the practice of the use of alginates rich in residues of α-L-guluronic acid for the removal of radioactive strontium from the digestive tract. The binding constants of Pb²⁺ ions to pectate over a wide range of binding densities are more than an order of magnitude greater than those of alkali-earth metal ions.     

Inhibitory activity of ginger rhizome on airway and uterine smooth muscle preparations

In this study, we describe the tracheal-relaxant and tocolytic activities of the methanol (ME) and aqueous (AQ) crude extracts of ginger (rhizome of Zingiber officinale) in an attempt to rationalize its traditional use in disorders of airways and uterine hyperactivity. Both of the ginger extracts dose-dependently relaxed K⁺ (80 mM) and carbachol (CCh, 1 μM)-induced contractions with more potency against K⁺, similar to that elicited by verapamil, a Ca²⁺ channel blocker. In isolated uterine preparations, the extracts suppressed the K⁺-induced contractions with respective EC₅₀ values of 0.03 mg/ml (0.02–0.05, 95% CI) and 0.05 mg/ml (0.04–0.06). Activity-directed fractionation of AQ yielded an organic and an aqueous fraction with the activities concentrated in the former. Both the crude extracts were found safe in mice up to the oral dose of 5 g/kg when tested for acute toxicity for 24 h. The study shows that ginger possesses tracheal and uterine smooth muscle relaxant activity, possibility mediated via Ca²⁺ channel blockade, justifying its use in disorders such as asthma, cough as well as in dysmenorrhoea and uterine and menstrual spasms and congestion.     

Biochemical properties and potential endogenous substrates of polyphenoloxidase from chufa (Eleocharis tuberosa) corms

Polyphenoloxidase (PPO) was partially purified from chufa corms through ammonium sulphate precipitation and dialysis. Biochemical properties of chufa PPO were analysed using exogenous substrate catechol. Optimal pH and temperature for PPO activity were 5 and 45 °C. Ethylenediaminetetraacetic acid disodium salt and l-cysteine could not inhibit the PPO activity. However, sodium thiosulphate pentahydrate exhibited the strongest inhibiting effect, followed by ascorbic acid and anhydrous sodium sulphite. Except for K⁺, other metal ions such as Zn²⁺, Cu²⁺, Fe³⁺, Ca²⁺, Fe²⁺ and Na⁺ accelerated the enzymatic reaction between catechol and PPO. Kinetic analysis showed that the apparent K_m and V_max values were around 10.77 mM and 82 units/ml min. In addition, (−)-gallocatechin gallate, (−)-epicatechin gallate and (+)-catechin gallate isolated and identified from chufa corms were supposed to be the potential endogenous PPO substrates due to their ortho-diphenolic or pyrogallolic structures. These polyphenols might be catalysed by PPO, resulting in the browning of chufa corms after fresh-cut processing.     

Pb2+Inhibits Competitively Flocculation of Saccharomyces cerevisiae

Pb²⁺inhibited calcium‐induced flocculation in Flo1 (S646–1B) and NewFlo phenotype strains (NCYC 1190, NCYC 1195 and NCYC 1364) of Saccharomyces cerevisiae. Flocculation was restored after washing with water or EDTA, which suggests a reversible binding of Pb²⁺to yeast cell walls. Pb²⁺probably inhibited flocculation by competing with Ca²⁺, since Pb²⁺inhibition was alleviated by excess of Ca²⁺. Using a fluorescent avidinfluorescein isothiocyanate (Avidin‐FITC) probe, active cell surface flocculation lectins, in the presence of Ca²⁺ions, were visualized. Conversely, Avidin‐FITC was not fixed to yeast walls of flocculent cells, in the presence of Pb²⁺ions or in the simultaneous presence of 0.05 mM Ca²⁺and 0.4 mM Pb²⁺. These results suggest that Pb²⁺ions were not able to induce the correct conformation of the lectin‐like component and reinforces the hypothesis that Pb²⁺ions compete for the same “calcium site” of flocculation zymolectins.     

Effects of metal ions on the self-assembly of chitosan molecules investigated with atomic force microscopy

The effect of different metal ions including K⁺, Na⁺, Mg²⁺, and Ca²⁺ at different concentrations on the self-assembly of chitosan molecules deposited on the new cleaved mica sheet was investigated using atomic force microscopy imaging techniques and other affiliated offline analysis methods. Chitosan molecules self-assembled porous film first when combined with K⁺, Na⁺, or Mg²⁺ ions, and then gradually fractured a granular structure with increasing concentration of metal ions. Chitosan molecules would be self-assembled to fibrous structure after adding calcium ions, and grew much thicker and more flat when the concentration increased. The investigations on the effects of metal ions on the self-assembly of chitosan molecules would be useful for food preservation, environmental protection, and pharmaceutical developments and industries.     

Influence of Ca2+, K+ and NO3− fertilisation on nutritional quality of pepper

A study was conducted in order to assess the effect of different fertilisation levels of Ca²⁺, K⁺ and NO₃^? on the bioactive nutrient content in red pepper (Capsicum annuum L) fruits. The experiment was carried out in a greenhouse, under hydroponic culture. Lycopene, β‐carotene, vitamin C, total phenolic compound, sugar, nitrate and potassium contents and antioxidant activity were determined. Increasing Ca²⁺ and NO₃^? concentrations in the root medium increased the lycopene and β‐carotene contents in pepper. Antioxidant activity was determined in the hydrophilic (HAA) and lipophilic (LAA) fractions. HAA was increased by intermediate and high Ca²⁺ concentrations in the culture medium. However, LAA was raised only by NO₃^? treatments. Vitamin C, sugar and total phenolic acid contents were not affected by Ca²⁺ or NO₃^? treatments. K⁺ treatments had no effect on nutritional quality of pepper. An increased supply of Ca²⁺ and NO₃^? in the culture medium could constitute a useful practice for improving the nutritional attributes of pepper as well as its commercial quality. Copyright © 2004 Society of Chemical Industry     

Isomerization of lactose catalyzed by alkaline-substituted sepiolites

Strong base catalysts, prepared by substituting a part of the Mg²⁺ located at the borders of the channels of sepiolite with alkaline ions (Li⁺, Na⁺, K⁺ and Cs⁺), were investigated as catalysts for the isomerization of lactose to lactulose and epilactose. The activities exhibited by alkaline-exchanged sepiolites were significantly higher than that of natural sepiolite. The influence of temperature, time of the reaction and catalyst loading were also evaluated. A 20% conversion was obtained at 90°C at a catalyst loading of 15 g litre⁻¹. ©     

Effect of Ethylenediaminetetraacetic Acid (EDTA) and Metal Ions on Growth of Staphylococcus aureus 196E in Culture Media

The effects of ethylenediaminetetraacetic acid (EDTA) and its salts, alone or in combination with Mg²⁺, Fe³⁺, Zn²⁺ or Ca²⁺, on growth of S. aureus strain 196E, were studied. EDTA or its Na⁺ or K⁺ salts (0.8–1.7 mM), but not its Ca²⁺ or Fe³⁺ salts, inhibited cell growth in Brain Heart Infusion broth. Bacteriostatic effects in Casamino Acids-Yeast Extract (CasY) broth were produced by 0.17 mM EDTA. Addition of Fe³⁺, Zn²⁺, or Ca²⁺ to EDTA-containing broth eliminated inhibition at an EDTA: cation molar ratio of 1:1, while Mg²⁺ required a sevenfold concentration. Data suggest that EDTA exerts its inhibitory effect by chelating calcium and/or other essential cations which form complexes with comparable stability constants with EDTA.     

Effects of Cation Properties on Sol-gel Transition and Gel Properties of κ-carrageenan

The phase transition temperatures, rheological properties and gel‐network characteristics for gelation of κ‐carrageenan‐salt (NaCl, KCl and CaCl₂) solutions and their aged gels were investigated. The effectiveness of increasing gelling and gel‐melting temperatures at the salt concentrations examined followed the sequence of K⁺ > Ca2⁺ > Na⁺. This sequence was also true for the gel strength and the melting enthalpy (DH) of the most crosslinked junction zones of aged gels at low salt concentrations. Nonetheless, a different order (Ca⁺⁺ > K⁺ and Na⁺) was found for increasing storage modulus and gelation rate during early‐stage gelation, thermal hysteresis and the DH of aged gels in some salt‐carrageenan systems.     

Ionized calcium requirement of rumen cellulolytic bacteria

Ionized calcium (Ca⁺²) appears to be required by the 3 predominant species of rumen cellulolytic bacteria, Fibrobacter succinogenes, Ruminococcus flavefaciens, and Ruminococcus albus. The present study evaluated the role of ionized calcium in growth and cellulose digestion. Maximum growth or rate and extent of digestion and lag time were the criteria used to evaluate Ca⁺² requirements. All cultures except F. succinogenes A3c grew when repeatedly transferred in a medium without added Ca⁺². As Ca⁺² concentration increased in cellobiose medium, the rate of growth increased and lag time decreased for F. succinogenes A3c, whereas F. succinogenes S85 exhibited increases in both maximum growth and rate of growth. No responses in any of the criteria were observed for the ruminococci in cellobiose medium. Both strains of F. succinogenes had an absolute requirement for Ca⁺² with cellulose as the only substrate. For strain A3c the requirement was 0.36 to 0.42 mM and for S85, >0.64 mM. Increases in extent of cellulose degradation occurred with all strains of ruminococci as Ca⁺² concentration increased; however, degradation in Ca⁺²-free medium was similar to that of F. succinogenes with Ca⁺². Although the ruminococci presumably have cellulosomes that require Ca⁺² in their structure, such was not evident in our studies. The function of Ca⁺² in cellulose degradation by F. succinogenes is unknown, but may be related to the secretion or activation of their cellulolytic enzymes. Based on reported concentrations of Ca⁺² in the rumen, it seems unlikely that an in vivo deficiency would occur for these bacteria.