Osmotic Values Research Articles

Seasonal Changes in Cold Hardiness of Temperate Collembola

The cold hardiness of two temperate collembolan species Orchesella cincta L. and Tomocerus minor (Lubbock) was compared. The supercooling points of the two show a bimodal distribution over the year with a group of high and of low values. Both groups show a distinct seasonal change. Adults and juveniles differ only slightly. 0. cincta has lower supercooling points than T. minor. This is in accordance with the fact that the former species lives more exposed than the latter. Frost induces gut evacuation in 0. cincta, which is considered a cold hardiness mechanism. Measurements on both ionized and the total osmotic fraction reveal that changes of the osmotic value of the haemolymph during winter are not caused by release of osmotically active cryoprotectants but by dehydration.

Tissue-fluid pressure measured in perfused rabbit hearts during osmotic transients.

To resolve discrepancies between models used to calculate myocardial capillary solute permeability we measured tissue-fluid pressure (Pi), perfusion pressure (Pp), and heart weight continuously after a step change in the NaCl or inulin concentration of crystalloid solutions perfusing isolated rabbit hearts. Linear regression analysis of the mean values for near steady-state Pi plotted against Pp showed significantly different (P less than 0.01) slopes of 0.77 and 0.40, respectively, for the inner and outer halves of the left ventricular free wall. Tissue compliance (Tcm) was measured as the fractional change in whole heart weight divided by the concurrent change in Pi. For NaCl and inulin osmotic transients Tcm values were 0.005 +/- 0.001 (SE) and 0.014 +/- 0.004 ml X cmH2O-1 X g tissue-1, respectively. A model for heart weight change based on the Starling hypothesis predicts significantly different tissue compliance (Tcc) values of 0.031 +/- 0.004 and 0.040 +/- 0.005 ml X cmH2O-1 X g tissue-1 for the same transients, respectively. This model shows myocardial capillary permeability for inulin and NaCl are overestimated by 25% if tissue compliance is not included in the analysis. The discrepancy between Tcm and Tcc is discussed.

Carbohydrate Metabolism of Salt-tolerant Fructan Grasses as Exemplified with Puccinellia peisonis

Summary The physiological role of carbohydrates, particularly of water-soluble fructose polymers (fructans), in metabolism was studied in Puccinellia peisonis, a salt-tolerant, caespitose grass growing at the banks of salty pools (“Lacken”) in the Seewinkel area (Burgenland, Austria). High resolution steric exclusion chromatography (SEC) made it possible to determine the molecular-weight distribution of the homologous fructan series and to quantify the individual components. The seasonal changes in the concentration of free monosaccharides, sucrose, oligo- and polyfructans (in 4 fractions with increasing molecular weight) and starch, which always occurred in small quantities, were studied in relation to the plant's phenology. Results showed that high-molecular fructans (with a degree of polymerization, DP of more than 18) mainly served as storage components, whereas fructose oligomers, similar to the raffinose series in many dicotyledonous species, provided resistance to freezing. Fructose and sucrose contributed much to the osmotic potential of the plant, which as most monocotyledonous species is highly efficient in excluding excess ions from the substrate. The resulting osmotic values, however, are too low to bridge dry periods in summer. In such cases decomposition of the water-soluble fructans may lead to a rapid increase of the osmotic potential. Moreover, the possible role of low molecular-weight fructans (with DP 7 to 10) as effectors of osmoregulation is discussed. The multiform functions of a polymeric series of simple carbohydrates may help to explain the success of Poaceae in growing on dry biotopes.

Tetracyclines, verapamil and nifedipine induce callose deposition at specific cell sites in Riella helicophylla

The Ca(2+) indicator 7-chlorotetracycline has been shown to bind to a pore complex on both outer surfaces of all non-meristematic cells in the unistratose thallus of Riella ('chlorotetracycline-binding surface region'=CSR; Grotha, 1983, Planta 158, 473-481). Prolonged treatment of the thallus with 7-chlorotetracycline, 5-hydroxytetracycline, verapamil and desmethoxyverapamil induces the deposition of callose at the same region. The influence of various treatments on verapamil-induced CSR-callose was measured in situ by microfluorometry of aniline-blue-stained material. Callose deposition is maximal at 10(-4)M verapamil or 5·10(-5)M desmethoxyverapamil with 2·10(-4)M Ca(2+) or Mg(2+) in the medium. The reaction is completely inhibited at pH 5.5 and is optimal between pH 6.5 and 7.5. The production of CSR-callose is absolutely light-dependent with callose being first visible after 30 min of light. La(3+), ethylene glycol-bis(β-aminoethylether)-N,N,N',N'-tetraacetic acid and amiprophosmethyl, antagonists of Ca(2+) functions, and 2-deoxy-D-glucose suppress the verapamil induction of CSR-callose. Furthermore the ionophores A 23187, valinomycin and monensin effectively block the reaction. The deposition of CSR-callose is diminished at increasing external osmolarity and is abolished at osmotic values that stimulate plasmolysis-callose. Wounding causes the formation of wound-callose but inhibits the induction of CSR-callose in cells of the wound edge. Nifedipine increases or prolongs callose synthesis in cell plates. The Ca(2+)-channel blocker diltiazem is completely ineffective. It is suggested as a working hypothesis that verapamil-induced CSR-callose synthesis is caused by a local change in membrane permeability, possibly as a consequence of the opening of Ca(2+) channels being involved in Golgi-vesicle mediated exocytosis (A. Kramer and H. Lehmann, 1986, Ber. Dtsch. Bot. Ges. 99, 111-121).

Cryopreservation of Digitalis lanata Cells Grown in vitro. Precultivation and Recultivation

Summary The protocol for successful cryopreservation of Digitalis lanata cell strains I and VII included the following steps: precultivation of the cells in mannitol-containing nutrient medium, treatment with cryoprotectors, cooling, storage in liquid nitrogen, rewarming, and recultivation. Cultivation in the presence of mannitol increased the osmotic value of the cells. After addition of cryoprotectors (glycerol, sucrose, DMSO) a high percentage of these cells survived slow cooling to −196 °C and rewarming, probably as the result of reduced dehydration. The processes of cooling and thawing caused injury to cell membranes. The thawed cells therefore released essential cell constituents. Recultivation had to be carried out using conditions which kept these losses minimal. Most suitable was cultivation of cells in high densities on the surface of solidified nutrient media, a method allowing slow decrease of the osmolality of the liquid surrounding the cells by diffusion of the cryoprotectors into the agar medium. The presence of the secondary product purpureaglycoside A within the cells caused a reduced vitality after cryopreservation. This was probably due to the loss of purpureaglycoside A from the storage compartment, the vacuoles, resulting in intoxication of the cytoplasm.

Water relations of rough lemon (Citrus jambhiri Lush.) citrus seedlings infected withFusarium solani

Rough lemon citrus seedlings were inoculated withFusarium solani and evaluated for changes in water relations of leaves, stems, and roots. Inoculated seedlings had decreased leaf stomatal conductance, lower leaf water potential, lower water content, and higher leaf osmotic values compared to healthy plants. Visible wilt symptoms occurred as early as 24 h after inoculation. Transpiration and root conductivity were lower in diseased plants but stem conductivity in diseased plants did not differ from the control. Thus, wilting appears to be due to the inability of roots to supply water to the leaves.

Volumetric behaviour and survival of mouse zygotes and embryos in hyperosmotic media.

Volume changes and survival of mouse zygotes and pre-implantation embryos were studied after their exposure to hyperosmotic media. Transfer of zygotes from culture medium to medium containing 1.5 M DMSO led to a rapid volume reduction to 60% of control values. After 10 min the volume was normal again, illustrating the rapid penetration of DMSO at room temperature. Re-transfer of zygotes equilibrated in 1.5 M DMSO to culture medium in one step doubled the volume. Twelve minutes later normal diameters were observed again. Volume changes were also recorded after transfer to media rendered hypertonic by the addition of NaCl or sucrose. A proportional decrease in volume was noticed up to 1500 mOsmol. A further increase in measured osmolarity up to 3100 mOsmol led only to limited further shrinkage of the zygotes (minimal volume observed was 27% of control volume). Addition of 1.5 M DMSO or 1.5 M propanediol had no influence on the final volume reaction to NaCl and sucrose. Exposure to media with a measured osmotic value of 3200 mOsmol (NaCl added) during 10 min did not prevent further development of the embryos to the hatched blastocyst stage. A solution of 4000 mOsmol proved lethal to nearly all embryos. Addition of 1.5 M DMSO to this medium did not have a protective effect against the osmotic stress at room temperature.

Effect of plasmolysis upon monovalent cation uptake, 9-aminoacridine binding and the zeta potential of yeast cells

The ζ potential of yeast cells shows a sudden decrease as the osmotic value of the medium is increased from 1.1 to 1.8 osmol. Above or below these values hardly any change in the ζ potential is observed. This decrease occurs by approximation in the range of osmotic values at which plasmolysis takes place. The surface potential of the yeast probed with 9-aminoacridine on the other hand does not change appreciably over the entire range of osmotic values used. The monovalent cation uptake rate declines gradually as the osmotic value of the medium increases. This seems to be caused by a concomitant rise in cellular K + which leads to a drop in the maximal uptake rate of monovalent cations. The K m of the monovalent cation uptake system is not changed by plasmolysis.

Relationship of respiratory pathways in soybean cell suspensions to growth of the cells at various glucose concentrations

Green soybean cells (Glycine max L.) were grown in suspension culture on B5-medium containing various glucose concentrations (2%, 4% or 8% glucose and 2% glucose + 2% or 6% mannitol). Respiratory parameters have been determined in these cells in relation to growth. The length of the growth phase and the amount of dry weight produced increased with higher glucose concentrations. In cells cultured in the presence of 2% glucose, 4% glucose or 2% glucose + 2% mannitol, the activity of the cytochrome pathway (V cyt )and the capacity of the alternative pathway (V alt )were not significantly different. Also the contribution of the alternative pathway to total respiration was essentially the same. The glucose content of cells grown in 2% or 4% glucose was roughly equal, which might explain the absence of any effect of the increased glucose concentration on the respiratory parameters. In cells grown in 8% glucose or on 2% glucose + 6% mannitol, both the activity of the cytochrome pathway and the capacity of the alternative pathway were lower. High values of ρ (approaching 1) were found in these cells, meaning that the alternative pathway is nearly fully operative. This is probably caused by the impairment of the cytochrome pathway due to the high osmotic value of the medium. ATP-production per batch per day has been calculated from oxygen uptake data, integrated and compared with cellular dry weight production to give values of 13-15.3 g dry weight produced mole ATP-1. The described experiments produce no direct evidence for a function of the alternative pathway as ‘energy overflow’ in soybean cells. The higher alternative pathway activity in the lag phase might be attributed to the great demand for intermediates during this phase.

Critical Parameters in the Isolation of Mitochondria from Candida utilis

The successive steps in the isolation of mitochondria from chemostat-grown Candida utilis have systematically been investigated for their effects on organelle integrity. Growth rate had a profound effect on the susceptibility of carbon-limited cells towards Zymolyase, whereas the nature of the carbon source had no effect. Stabilization of spheroplasts with at least 2M-sorbitol was required to prevent premature lysis. This was concluded from the amounts of glucose-6-phosphate dehydrogenase liberated during Zymolyase treatments. The influence of the method for disruption of spheroplasts on the quality of the mitochondria was analysed with particular emphasis on respiratory control values and the distribution of marker enzymes among the cell fractions. Disruption by osmotic shock resulted in mitochondria without respiratory control and a high degree of solubilization of NADH and NADPH dehydrogenase activities. Only a gradual decrease of the osmotic value of the medium, preferably by dialysis against a hypotonic buffer, in combination with mechanical disruption with a Potter-Elvehjem homogenizer yielded mitochondria with high respiratory control values and a high retention of NADH dehydrogenase in the organelle. It is concluded that, for the quality of mitochondrial preparations from yeasts, the distribution of NADH dehydrogenase among the cell fractions is a more reliable measure than that of the usual marker enzymes.

Inhibierungserscheinungen bei der alkoholishchen Gärung III. Der Einfluß des osmotischen Druckes auf die Lebensfähigkeit von Saccharomyces cerevisiae

AbstractThe influence of the osmotic pressure on the viability of yeast cells was studied in batch processes. It could be found, that the viability is a function of the total osmotic pressure obtained by adding the partial osmotic values of the principal ingredients saccharose, ethanol and salts dissolved in the medium. At optimum process conditions (pH, T, etc.) the cells can tolerate the osmotic pressure up to fixed value π1. Above π1 the viability decreases linearly and upward of a second threshold value π2 nonlinearly. In the case of the used strain Saccharomyces cerevisiae Hansen Sc 5 the values of the both points are π1 = 25 atm and π2 = 47 atm.

An optimized hyperfiltration process for concentrating aqueous solutions of high osmotic pressure

A continuous process is described in which a combination of low and high retention membrane modules is applied. Such a combination can give higher production rates and lower product losses than conventional hyperfiltration processes. Moreover it gives the possibility to concentrate solutions to osmotic values higher than the applied pressure. The process, optimized by computer simulation, appears to be competitive with multi-effect evaporation even in relatively high osmotic pressures.

Determination of permeability coefficients, reflection coefficients, and hydraulic conductivity ofChara corallina using the pressure probe: Effects of solute concentrations

The pressure probe technique which has been used for measurement of water relations parameters of plant cells [hydraulic conductivity (Lp), elastic modulus (e) and half-time of water flow equilibration for individual cells (T12/w)] can be used also for measuring reflection and permeability coefficients (σ,Ps) of permeable solutes. In the presence of a permeable osmoticum the pressure/time curves are biphasic, i.e. after a rapid water flow bringing turgor pressure to a minimum value (Pmin), a second phase occurs in which turgor pressure increases back to the original value (Po). The second phase (“solute phase”) is due to an equilibration of the solute across the cell membrane and can be used to evaluatePs. The responses are strictly reversible, i.e. when the osmoticum is removed a pressure maximum is quickly reached followed by a slower equilibration of solute. The reflection coefficients for the solutes can be calculated from the change in osmotic pressure of the medium (Δψs0) and from the change in turgor at the minimum (Po−Pmin) after correcting for solute flow. For internodal cells ofChara corallina, reflection and permeability coefficients for certain nonelectrolytes (sugars, polyols, monohydroxyalcohols, amides, ketones) are given and compared with data obtained by other methods. ForChara, Ps and osmotic values ofLp depended on external stirring, whereas σ corrected for solute flow did not. As expected hydrostaticLp did not depend on stirring. No polarity of water flow was found for hydrostaticLp (Lpen/Lpex=1.02±0.05, 95% confidence limits) whereas a polarity was observed for osmoticLp which can be explained in terms of a concentration effect. Using permeable solutes, the concentration dependence ofLp, σ andPs could be measured over large concentration ranges (up to 1.4m) at constant cell turgor.Ps was independent of solute concentration for concentrations up to 1.4m while both σ andLp decreased with increasing concentration such that there was a linear relationship between (1−σ) and 1/Lp as predicted by the frictional model for a lipid membrane with pores. The slope of the (1−σ)vs. 1/Lp plot gives a value ofPs and the intercept with the (1−σ) axis gives the degree of frictional interaction between solute and water. The frictional term was found to be significantly greater than zero. The values ofPs evaluated from the solute phase were smaller than those obtained from the (1−σ)vs. 1/Lp plots. However, they were of the same order of magnitude and showed the same sequence for the different solutes. The technique for determiningPs and σ is of importance for obtaining quantitative data for the permeation of water-soluble pollutants into plant cells and tissues and for their ecotoxicological significance.

Storage of Osmotically Active Compounds in the Taproot ofDaucus carotaL.

The osmotic potential of cell sap from the storage root, lateral roots and shoots of carrot (Daucus carota L., cv. Amsterdamse Bak) was calculated from the concentration of osmotically active compounds in these tissues. The osmotic potential of the taproot did not change with age prior to and during the storage of osmotically active sugars, as sucrose and reducing sugars. The increased contribution of soluble sugars in the osmotic potential was accompanied by a proportionally decreased contribution of potassium and organic acids. Before storage of soluble sugars in the taproot occurred, potassium and organic acids contributed 80% to the total osmotic value, in contrast with lateral root tissue, where potassium and nitrate were the main osmotic solutes. The concentration of osmotically active solutes was lower in lateral root tissue than in storage root tissue. Shoot tissue resembled taproot tissue before storage, in having potassium and organic acids as the main osmotic solutes. The concentration of osmotically active solutes was highest in shoot tissue and it increased towards the end of the experimental period. The calculated osmotic potentials were in good agreement with the experimental values, as determined from the molecular depression of the freezing point of cell sap. Storage of reducing sugars and sucrose is discussed in relation to acid and neutral invertase activities.

Concentrated, polydisperse solutions of colloidal particles. Light scattering and sedimentation of hard-sphere mixtures

The usefulness of the hard-sphere model in characterizing polydispersity in concentrated colloidal solutions is stressed. A recently derived equation for ( ∂ρ i / ∂μ j ) μ is used to give a simpler route for application to light scattering and sedimentation in multicomponent and polydisperse systems. Some light-scattering intensity calculations are performed for a log-normal distribution of hard-sphere diameters. Special attention is given to the contribution of fluctuations in the osmotic value to the lightscattering intensity of polydisperse systems.

Measurements of serum colloid osmotic pressure are of limited usefulness.

We examined the usefulness of serum colloid osmotic pressure measurement in patients with chronic rather than acutely occurring low serum protein concentrations. We used two oncometers, the IL 186 Weil Oncometer and the Wescor Model 4100; results from the two instruments were interchangeable. Values for the colloid osmotic pressure were compared with those for serum total protein (r = 0.783) and albumin concentrations (r = 0.882), which were similar to previously published values. Our day-to-day CV was 2.8%. In studying over 100 patients we found that the previously reported occurrence of pulmonary edema in almost all patients whose colloid osmotic pressure was less than 12.5 mmHg was not seen in the chronic hypoproteinemic patients. We noted only one fatality in our patients whose colloid osmotic pressure was less than 10.5 mmHg, a value found to be associated with fatality in one previous study of acutely ill patients. Factors such as ambulation, fasting, dehydration, and the nature of the blood sample can markedly affect the value for colloid osmotic pressure value, and this, coupled with the good correlation with the serum albumin in several studies, leads us to question the usefulness of measuring colloid osmotic pressure in a non-specialist hospital environment, either as an adjunct to the measurement of serum protein or albumin, or as an independent test.

Eco-physiological studies on desert plants X. Contribution to the autecology of the desert chasmophyte Stachys aegypticca Pers.

Stachys aegyptiaca Pers. is a desert calcicolous chasmophyte. Its growth in the Egyptian Desert is confined to the limestone formations of the Northern Arabian Desert, Sinai and the Isthmic Desert. The plant lives under harsh climatic conditions: high summer temperatures with mean maxima above 35°C and low rainfall ranging from 9.4 mm/annum at El-Tor to 87.3 mm/annum at Hemme.The vegetation dominated by Stachys aegyptiaca is a pioneer stage in the development of the wadi bed ecosystem. Other chasmophytes are the main associates of the Stachys community. The studied plant has been recorded among the associates of numerous plant communities.Runoff, accelerated by the rugged topography in areas where the plant grows, and the stoniness of the substratum contribute to securing ample water supply to the plant.The daily march of the transpiration rate was investigated in two seasons. It has been clear that there is an obvious regulation of transpiration in summer.The osmotic pressure of the plant sap was determined at regular monthly intervals throughout one year. The average osmotic value is 17 atm, ranging from 13.8 atm in April to 19.3 atm in November.

Leaf Characteristics of the Flora of the High Plateau of Itatiaia, Brasil

The high-mountain flora at Itatiaia, Brasil, consists of graminoid plants intermingled with evergreen shrubs with xeromorphic leaves which at first glance look all rather similar. Leaf characteristics such as leaf size, degree of hairiness, maximal potential hydration level, leaf-area development, degree of sclerophylly, and degree of succulence were determined for 30 common species. Xeromorphic features, though clearly developed in the flora, are not extreme. Leaves are small, varying from nanophyllous to mesophyllous; leaf-area development values and sclerophylly values are fairly high, and succulence values rather low. Four strategy types in the leaves of the Itatiaia species can be identified, and are discussed in terms of the cost-income model of leaves presented by Orians and Solbrig (1977). Maximal potential hydration levels are rather constant during the course of the relatively dry winter season, thus suggesting that the plants are predominantly hydrostable. For two species, variability in leaf parameters of plants occurring on sites with contrasting water conditions are discussed and interpreted in terms of their ecological amplitude. IN GRISEBACH'S (1872) WELL-KNOWN ACCOUNT of the vegetation of the world, an early attempt was made to correlate leaf morphology and climate. In 1915 and 1916 Bailey and Sinnott reported on correlations between leaf-margin features of dicotyledonous species and their distribution in the broad climatic zones of the world. Since then the theme of leaf characteristics as expressions of local macroclimate has frequently recurred in botanical literature, particularly in palaeobotanical studies (e.g., Wolfe 1971, Dolph 1979, Dolphl and Dilcher 1979). Leafsize spectra for specific vegetation types, particularly for tropical forests, have been calculated and compared as a contribution toward a characterization of the structural composition of the communities (cf. De Sloover et al. 1965b, and Werger and Ellenbroek 1978 for several references); also changes in leafsize spectra in a successional series have been compared (e.g., Barkman 1979). Leaf consistency has long been regarded as an important indicator of environmental conditions. Schimper (1898) discussed hygromorphic and xeromorphic structures in leaves in terms of adaptations to physiologically wet and dry habitats respectively. Significant contributions in this respect were the work of Huber (1925), who pointed out the importance of a plant's ability to regulate the osmotic value of its plasma under changing environmental water conditions, and the results of Miiller-Stoll (1947-1948), who complemented the findings of Firbas (1931) in showing that xeromorphic characters in bog plants diminish under nitrogen fertilization. Beadle (1966) pointed out a similar role for phosphate in Australian xeromorphic plants, and Steubing and Alberdi (1973) also showed that sclerophylly (though differently defined) increases with decreased availability of phosphate. Walter (1968, 1972, 1973; Walter and Kreeb 1970) discussed various examples of xeromorphic (or peinomorphic) features in plants stressing the great differences in water-balance strategies in xeromorphously appearing

Colloid chemical studies on bitumen-in-water emulsions part I. absorption of water in the bitumen droplets and other factors affecting emulsion viscosity

Various factors determining the viscosity of bitumen-in-water emulsions are discussed. A procedure is described to assess the extent of absorption of water by the bitumen (formation of multiple phase droplets). The method is based on measuring the change in viscosity when the osmotic value of the continuous phase is increased. Use is made of a simple relation between the relative viscosity and the volume fraction of the dispersed phase. The effect of polydispersity on the viscosity is also discussed.

Effects of mercuric chloride and methylmercuric chloride on the osmoregulatory function of the gills in rainbow trout, Salmo gairdneri Richardson

1. 1. The study concerns the effects of mercuric chloride (MC) and methylmercuric chloride (MMC) on the ionic composition and osmotic value of the blood, Na + −K + -ATPase activity in the gills and rate of water uptake by the gills in rainbow trout ( Salmo gairdneri). 2. 2. MC and MMC, when administered in the water or via perfusion of the gills, inhibited Na + −K + ATPase activity in the gills, but only at lethal concentrations. Plasma concentrations of Na + and Cl − were decreased by both compounds, even at sublethal concentrations. At these lower mercury levels a markedly enhanced water uptake by the gills was measured. 3. 3. The results lead to the conclusion that a change in the permeability characteristics of the gills for water, rather than an inhibition of the Na + −K + -ATPase of the gills, is the primary reason for the mercury-induced effects on osmoregulation in rainbow trout.