Ionic Osmotic Pressure Research Articles

Synthesis of pH‐sensitive inulin hydrogels and characterization of their swelling properties

In this study, pH-responsive inulin hydrogels were prepared by radical copolymerization of methacrylated inulin (MA-inulin) with acrylic acid (AAc) in aqueous solution using ammonium peroxydisulfate (APS) and N,N,N',N'-tetramethylethylenediamine (TMEDA) as an initiation system. The AAc content in hydrogels was evaluated by FTIR spectroscopy. The covalent bridging of AAc among MA moieties of MA-inulins was observed by a significant increase in the effective network density of hydrogels and further confirmed by TGA studies. While, at a low content of AAc, the hydration of hydrogels at pH 7.4 decreased owing to the increased crosslinking density, the swelling subsequently increased with further increasing AAc as a consequence of the increased ionic osmotic pressure within hydrogels. The change in swelling of hydrogels in response to pH change between 7.4 and 2.2 was therefore enlarged when the AAc content increased.

Patch-clamp experiments with porins extracted from a marine bacterium (Photobacterium profundum strain SS9) and reconstituted in liposomes.

The reconstitution of bacterial porins in liposome bilayers for patch-clamp recording is well established. However, the solutions used in the dehydration, rehydration, and osmotic swelling of the liposomes have been developed for porins from enteric bacteria. Porins from marine bacteria normally function in contact with seawater whose ionic composition and osmotic pressure would appear to be incompatible with the established methods. Here, we show that, contrary to expectation, an established reconstitution and patch-clamp method works well with porins, mainly OmpH and OmpL, extracted from the deep-sea marine bacterium Photobacterium profundum strain SS9 and that seawater can be introduced at a supplementary stage.

Surface friction of polymer gels: 2. Effect of charge

The friction between two chemically cross-linked polyelectrolyte gels carrying the same sign of charges has been investigated in pure water as well as in salt solutions. The friction was largely dependent on the charge densities of the gel surface and the ionic strength of the aqueous solution. The friction is described in terms of the hydrodynamic lubrication of the solvent layer between the two gel surfaces, which is formed due to the electrostatic repulsion of the two gel surfaces. The thickness of the solvent layer is estimated using the Poisson–Boltzmann equation supposing that the ionic osmotic pressure is balanced by the normal pressure applied on the gel. The friction values are calculated by considering the shear flow of solvent in the gel region using the Debye–Binkman equation. For strongly charged polyelectrolyte gels swollen in pure water, the theoretical analysis shows that the friction coefficient has almost no dependence on the water content of the gel, which agrees well with the experimental observations.

Physiological Saline Suitable for the Marine Isopod Crustacean Bathynomus doederleini

In order to establish the physiological saline suitable for the giant marine isopod Bathynomus doederleini, we analyzed ionic compositions, pH and osmotic pressure of the hemolymph. We made three test salines on the basis of ionic compositions of the hemolymph. Saline A contains surplus Cl− (89.5 mM over in comparison with the serum) and no SO42−. Saline B contains surplus Cl− (71.4 mM over) and normal SO42−. Saline C contains normal Cl− and surplus SO42− (35.7 mM over). We examined the effects of the test solutions and other salines on activities of isolated hearts. The heart in the salines continued to beat regularly more than 20 hr at 20°C. Heart rate in the test solutions was significantly higher (saline A: 66.5±5.1/min, n=8, saline B: 60.4±7.0/min, n=9, saline C: 67.9±8.4/min, n=8) than that in sea water (SW: 50.2±4.8/min, n=10) and was significantly lower than that in the saline for decapod which was originally designed by Pantin (Pantin's saline : 77.6 ±8.9 /min, n=8). Among the test salines, there were no significant differences in heart rate, systolic force and membrane potential of cardiac ganglionic neuron and myocardial cell. The standard physiological saline for Bathynomus was determined as follows (mM) ; Na , 479.4; K , 15.7; Ca2 , 14.6; Mg2 , 60.7; Cl−, 627.6; SO42−, 9.1; HEPES, 5; pH 7.9.

Genetic analysis of salt-tolerant mutants in Arabidopsis thaliana.

Stress caused by the increased salinity of irrigated fields impairs plant growth and is one of the major constraints that limits crop productivity in many important agricultural areas. As a contribution to solving such agronomic problems, we have carried out a large-scale screening for Arabidopsis thaliana mutants induced on different genetic backgrounds by EMS treatment, fast neutron bombardment, or T-DNA insertions. From the 675,500 seeds we screened, 17 mutant lines were isolated, all but one of which yielded 25-70% germination levels on 250 mm NaCl medium, a condition in which their ancestor ecotypes are unable to germinate. Monogenic recessive inheritance of NaCl-tolerant germination was displayed with incomplete penetrance by all the selected mutants, which fell into five complementation groups. These were named SALOBRENO (SAN) and mapped relative to polymorphic microsatellites, the map positions of three of them suggesting that they are novel genes. Strains carrying mutations in the SAN1-SAN4 genes display similar responses to both ionic effects and osmotic pressure, their germination being NaCl and mannitol tolerant but KCl and Na(2)SO(4) sensitive. In addition, NaCl-, KCl-, and mannitol-tolerant as well as abscisic-acid-insensitive germination was displayed by sañ5, whose genetic and molecular characterization indicates that it carries an extremely hypomorphic or null allele of the ABI4 gene, its deduced protein product lacking the APETALA2 DNA binding domain.

Friction of Gels. 4. Friction on Charged Gels

The friction between two chemically cross-linked polyelectrolyte gels carrying the same sign of charges has been investigated in pure water as well as in salt solutions using a rheometer. It is found that the friction was largely dependent on the charge densities of the gel surface and the ionic strength of the aqueous solution. The chemical structures of the polyelectrolyte gels also play an important role. The friction is described in terms of the hydrodynamic lubrication of the solvent layer between the two gel surfaces, which is formed due to the electrostatic repulsion of the two gel surfaces. The thickness of the solvent layer has been estimated using the Poisson−Boltzmann equation supposing that the ionic osmotic pressure is balanced by the normal pressure applied on the gel. The friction values have been calculated by considering the shear flow of solvent in gel region using the Debye−Binkman equation. For strongly charged polyelectrolyte gels swollen in pure water, the theoretical analysis shows that the friction coefficient almost has no dependence on the water content of the gel, which well agrees with the experimental observations.

Modification of fatty acid composition in halophilic antarctic microalgae

The major fatty acids in two Dunaliella isolates originating from Antarctic hypersaline lakes were 18:3 ω3, 16:0, 16:4 ω3. 18:1 ω9, 18:2 ω6, and 16:1 ω7. The relative amount of individual fatty acids was modified by partially or fully replacing ionic osmotic pressure (Na +, K + and Cl −) with molecular osmotic pressure (sorbitol) in the growth medium. The effects of sorbitol on the extent of cellular fatty acid unsaturation differed in the two isolates. The results suggest that the appropriate environment necessary for the growth of these halophilic species is a certain level of osmotic pressure in the medium, but that this can be provided by either ionic or molecular osmotic pressure, or a mixture of both.

Application of “Four-Plane Model” to the Adsorption of K+, NO3-, and SO42-from a Mixed Solution of KNO3and K2SO4on Andisols

Abstract To evaluate the interaction between anionic species when they were adsorbed on variable charge soils, we measured the adsorption of NO3 - and SO4 2- on. an Andisol equilibrated with a mixture of KNO3 and K2SO4 solutions. The amount of NO3 - adsorption declined with the increase in the concentration of SO4 2-. On the other hand, the amount of SO4 2- adsorption increased with the increase in the concentration of NO3 -. These phenomena can not be explained by the simple “exchange theory” or the “Three-plane model” unless surface complexation is associated with the changes in the electrical potential of the surface. Therefore, in order to explain the phenomena by using the “Four-plane model” with surface complexation, a new equation was derived for the Diffuse Double Layer (DDL) charge from the “main equation of DDL theory” (equation of electrical potential in DDL) instead of the “Gouy-Chapman equation,” which can be used only for single symmetric electrolytes but nor for a mixture. By introducing the new equation to the computer program for analyzing the Four-plane model, the interaction between anionic species adsorbed on Andisols could be explained well. It was considered that SO4 2- acted as a regulator for the ionic concentration, osmotic pressure and pH of the soil solution, and consequently, these factors affected the vertical distribution and mobility of anionic species and also the mobility of counter-ions in Andisols.

Hypothalamic integration of body fluid regulation.

The progression of animal life from the paleozoic ocean to rivers and diverse econiches on the planet's surface, as well as the subsequent reinvasion of the ocean, involved many different stresses on ionic pattern, osmotic pressure, and volume of the extracellular fluid bathing body cells. The relatively constant ionic pattern of vertebrates reflects a genetic "set" of many regulatory mechanisms--particularly renal regulation. Renal regulation of ionic pattern when loss of fluid from the body is disproportionate relative to the extracellular fluid composition (e.g., gastric juice with vomiting and pancreatic secretion with diarrhea) makes manifest that a mechanism to produce a biologically relatively inactive extracellular anion HCO3- exists, whereas no comparable mechanism to produce a biologically inactive cation has evolved. Life in the ocean, which has three times the sodium concentration of extracellular fluid, involves quite different osmoregulatory stress to that in freshwater. Terrestrial life involves risk of desiccation and, in large areas of the planet, salt deficiency. Mechanisms integrated in the hypothalamus (the evolutionary ancient midbrain) control water retention and facilitate excretion of sodium, and also control the secretion of renin by the kidney. Over and above the multifactorial processes of excretion, hypothalamic sensors reacting to sodium concentration, as well as circumventricular organs sensors reacting to osmotic pressure and angiotensin II, subserve genesis of sodium hunger and thirst. These behaviors spectacularly augment the adaptive capacities of animals. Instinct (genotypic memory) and learning (phenotypic memory) are melded to give specific behavior apt to the metabolic status of the animal. The sensations, compelling emotions, and intentions generated by these vegetative systems focus the issue of the phylogenetic emergence of consciousness and whether primal awareness initially came from the interoreceptors and vegetative systems rather than the distance receptors.

A hydrogel with rubber elasticity transition

AbstractReaction between dimethyldivinylsilane and 3,6‐diazaoctane in the presence of 3‐lithio‐3,6‐diazaoctane yields a new telechelic oligomer, poly(silamine), which consists of alternating 3,3‐dimethyl‐3‐silapentane and N,N′‐diethylethylenediamine units in the main chain. Poly(silamine) shows unique phase transition properties in response to the degree of protonation of amino groups in the polymer. Poly(silamine) also shows a strong interaction with several anions. Due to the interaction between poly(silamine) and anions along with the protonation of amino groups in the poly(silamine), the rubber elasticity of poly(silamine) is drastically changed. A discrete volume change can be observed when the environmental pH of the poly(silamine) gels is varied. This can be explained not only by a change in ionic osmotic pressure but also by a change in the rubber elasticity of the networks in the gel.

Ionic Stress and Osmotic Pressure Induce Different Alterations in the Lipopolysaccharide of a Rhizobium meliloti Strain

A halotolerant strain of Rhizobium meliloti was isolated from nodules of a Melilotus plant growing in a salt marsh in Donana National Park (southwest Spain). This strain, EFB1, is able to grow at NaCl concentrations of up to 500 mM, and no effect on growth is produced by 300 mM NaCl. EFB1 showed alterations on its lipopolysaccharide (LPS) structure that can be related to salt stress: (i) silver-stained electrophoretic profiles showed a different mobility that was dependent on ionic stress but not on osmotic pressure, and (ii) a monoclonal antibody, JIM 40, recognized changes in LPS that were dependent on osmotic stress. Both modifications on LPS may form part of the adaptive mechanism of this bacterium for saline environments.

Fluid Balance in the Argasid Tick, Ornithodorus Moubata, Fed On Modified Blood Meals

ABSTRACT The argasid tick Ornithodorus moubata Murray was fed on modified blood meals, the ionic strength and/or osmotic pressure of which was varied by additions of NaCl or glucose, and by dilution with distilled water or isosmotic glucose. The following parameters were monitored: total volume increase of tick, total volume of meal ingested, net increase in haemolymph volume, volume of coxal fluid excreted and ion concentrations and osmotic pressures of the gut contents, haemolymph and coxal fluid, as well as potential differences across the gut lumen. Absorption of fluid from the gut into the haemolymph appeared to be linked to the active transport of Na+ and Cl−, although the rate of absorption was an inverse function of the prevailing osmotic gradient across the gut epithelium. The tick can maintain a reasonably constant [Na+] and [Cl−] in the haemolymph when fed meals in which the concentration of these ions varies up to 6-fold, but only if the meal remains isosmotic with blood. The rate and volume of coxal fluid production are direct functions of the rate and volume of fluid absorption by the gut epithelium. Thus, during the feeding cycle, the coxal organ appears to function chiefly in an osmo- and volume-regulatory capacity in this species of argasid tick.

Sparing effect of lithium ion on the specific requirement for sodium ion for growth of Vibrio parahaemolyticus.

The role of NaCl in the growth of Vibrio parahaemolyticus strain A-55 was investigated. Maximal growth was obtained at 0.5 M NaCl in a synthetic medium. Na+ could not be replaced for growth by any other cations or substances. When the medium was kept isotonic with 0.5 M NaCl by the addition of sucrose, good growth was obtained with 0.1 M NaCl. By reducing the osmotic pressure and decreasing the NaCl concentration from 0.5 M to 0.1 M, the same growth yield was obtained as when using a medium containing 0.02 M NaCl and 0.08 M LiCl. This was not the case with sucrose. Therefore, it is concluded that ionic strength and osmotic pressure are important environmental factors affecting growth. The minimal essential requirement for Na+ for growth of V. parahaemolyticus was 0.003 M, because this was never replaced with any other cations and agents. Hence, requirement for Na+ for growth involves a specific requirement for Na+, ionic strength, and osmotic pressure, respective concentrations being 0.003 M, 0.047 M, and 0.45 M. Osmotic support was required for growth when the concentration of NaCl was decreased to 0.05 M. The effect of ionic strength of monovalent cations other than Na+ on growth was examined at 0.003 M NaCl. Among LiCl, NH4Cl, KCl, and RbCl, Li+ was the most accelerative for growth in the synthetic medium.

Osmotic regulation in the marine alga, Codium decorticatum. I. Regulation of turgor pressure by control of ionic composition.

Codium decorticatum regulates its internal ionic composition and osmotic pressure in response to changes in external salinity. Over a salinity range of 23 to 37% (675 to 1120 mosmol/kg) Codium maintains a constant turgor pressure of 95 mosmol/kg (2.3 atm), observed as a constant difference between internal and external osmotic pressures. The changes in internal osmotic pressure are due to changes in intracellular inorganic ions. At 30 0/00 salinity the major intracellular ions are present in the following concentrations (mmol/kg cell H20): K+, 295; Na+, 255; Cl-, 450. At different salinities intracellular ion concentrations remain in constant proportion to the external ion concentrations, and thus the equilibrium potentials are approximately constant. The potential difference between the vacuole and seawater (-76 mV), whici is predominantly a K+ diffusion potential, is also constant with changing salinity. Comparison of the equilibrium potentials with the vacuole potential suggests that Cl- is actively absorbed and Na+ actively extruded, whereas K+ may be passively distributed between the vacuole and seawater. Turgor pressure does not change with environmental hydrostatic pressure, and increasing the external osmotic pressure with raffinose elicits a response similar to that obtained by increasing the salinity. These two results suggest that the stimulus for turgor regulation is a change in turgor pressure rather than a change in internal hydrostatic pressure or ion concentrations.

Effect of osmotic pressure on spontaneous afferent discharge in the nerves of the perfused rabbit liver.

Rabbit livers were perfused with Krebs solution via the portal vein and small bundles of the hepatic nerve were monitored for spontaneous afferent impulses arising in the liver. The concentration of the Krebs solution was varied by altering the amount of water in which the salts were dissolved. An alteration from 5% more concentrated to 5% more dilute and vice versa did not affect this spontantous discharge. Addition to the Krebs solution of up to 60 mM sucrose, of up to 22 mM mannitol or of 0.8 mM polyethylenglycol 6000 mol. wt. did not alter the frequency of impulses. Perfusion with bovine serum, or Krebs solution containing approx. 0.6 mM polyvinylpyrrolidone, mol. wt. 44000, or dextran mol. wt. 110000 increased the frequency of discharge in some nerve bundles. An alteration of 0.06 mM in the concentration of dextran produced a significant change of frequency. It is concluded that spontaneous discharge in some afferent hepatic nerves is influenced by colloidal osmotic pressure but not by changes of ionic osmotic pressure. The nerves affected differ from 'sodium-sensitive' nerves and from the 'osmoreceptors' of Niijima.

A saline medium for maintaining isolated heart ofPila globosa, swainson

Some known standard salines for molluscs were found unsuitable for maintaining the heart ofPila in vitro. A new saline forPila has been devised keeping in view the ionic composition, pH and osmotic pressure of blood ofPila. A saline having the composition of blood was not found suitable for maintaining isolated heart ofPila but reduction of percentage of potassium made it so. The osmotic pressure was adjusted with addition of glucose which also provides energy. Changes of pH between 5 and 8·5 did not have an effect on the heart-beat ofPila. It was suggested that a saline containing only the principal ions of blood was not suitable because other trace and organic substances present in the blood were perhaps playing an important role in the regular beating of the heart. Adjustment in the proportion of different ions and addition of glucose did partly compensate for the absence of these substances.

Physical Variables in the Olfactory Stimulation Process

Electrical recording from small twigs of nerve in a tortoise showed that olfactory, vomeronasal, and trigeminal receptors in the nose are responsive to various odorants. No one kind of receptor was most sensitive to all odorants. For controlled stimulation, odorant was caused to appear in a stream of gas already flowing through the nose. Of the parameters definable at the naris, temperature, relative humidity, and nature of inert gas had little effect on olfactory responses to amyl acetate, whereas odorant species, odorant concentration, and volume flow rate effectively determined the responses of all nasal chemoreceptors. An intrinsic variable of accessibility to the receptors, particularly olfactory, was demonstrated. Flow dependence of chemoreceptor responses is thought to reflect the necessity for delivery of odorant molecules to receptor sites. Since the olfactory receptors are relatively exposed, plateauing of the response with flow rate for slightly soluble odorants suggests an approach to concentration equilibrium in the overlying mucus with that in the air entering the naris. Accordingly, data for responses to amyl acetate were fitted with Beidler's (1954) taste equation for two kinds of sites being active. The requirement for finite aqueous solubility, if true, suggests substitution of aqueous solutions for gaseous solutions. A suitable medium was found and results conformed to expectations. Olfactory receptors were insensitive to variation of ionic strength, pH, and osmotic pressure.

Hemolysis and the release of potassium from cells by Newcastle disease virus (NDV)

Hemolysis by NDV was preceded by a rapid release of potassium from the cells and by cell swelling. The potassium release reflected an increased cation permeability of the cell due to the action of the virus. This caused an over-all rise in the internal ionic concentration and osmotic pressure due to the influx of ions from the medium, and led to cell swelling and lysis. Antiserum abolished the reaction of the virus with the cell. Hemolysis was inhibited also by substances that prevented cell swelling but did not affect the initial action of the virus. Cell swelling and hemolysis were reversibly inhibited by albumin, which raised the external osmotic pressure, and by calcium, which probably reduced the cation permeability of the cells. Phloridzin inhibited hemolysis irreversibly by diminishing cell swelling in an unexplained manner. Hemolytic viruses also released potassium and protein from HeLa cells and ascites tumor cells. No detectable release of potassium occurred in the presence of other viruses that are known to infect these cells. The release of large amounts of potassium is therefore due to the hemolytic action of a virus and is not associated with the initiation of infection.

Mayer's Treatment of Ionic Solutions

Mayer's expressions for the ionic activity coefficient and osmotic pressure of an electrolyte solution are shown to involve known and accurately tabulated functions. Mayer's infinite series of integrals is summed to give a single integral involving the Debye-Huckel potential of average force. With the help of the new form, the use of the single cut-off parameter for binary electrolytes is discussed from a quantitative standpoint.

Ion Activities and Osmotic Pressures in Clay‐Water Systems

AbstractOsmotic pressures of H‐, Na‐, and K‐bentonite suspensions were measured with an Adair osmometer. Measurable osmotic pressures were observed, but the values were quite small, ranging from 0.6 cm H2O for 1% Na‐bentonite to 4.2 cm H2O for 4% H‐bentonite. The ion activity difference across the osmometer membrane, calculated from the membrane potential and the ion concentration on the solution side, was large. The ionic osmotic pressure difference across the membrane, from the van't Hoff approximation, was much larger for all systems than was the observed osmotic pressure, leading to the conclusion that the membrane potential cannot be regarded as a measure of an electrostatic potential difference between a clay suspension and its equilibrium dialysate.Electrolyte mean activities of KCl solutions were consistently slightly smaller than in 2% K‐bentonite suspensions of the same normality of KCl. Mean activities of KCl in the clay suspensions were much smaller than K+ activities measured with a membrane electrode‐saturated calomel electrode cell.The osmotic pressure data and potentiometric data are interpreted as indicative of a spurious potential at a clay‐salt bridge junction.