A NEW METHOD FOR THE DETERMINATION OF OSMOTIC PRESSURE

Lockhart , James A. (California Inst. Tech., Pasadena.) A new method for the determination of osmotic pressure. Amer. Jour. Bot. 46(10): 704–708. Illus. 1959.—A new method for the determination of osmotic pressure in appropriate plant tissues is described. This method is based on the observation that the degree of deformability of tissue equilibrated in hypertonic solution is a linear function of the extent by which the external osmotic pressure exceeds the osmotic pressure of the cell contents. Extrapolation of the deformability vs. external osmotic pressure to zero deformation yields, then, the osmotic pressure of the tissue at limiting plasmolysis. It is shown that the osmotic pressure determinations are independent of incubation time and magnitude of applied force. A simple device is described for measuring bending throughout a wide range of angles, while keeping the applied force constant.     

渗透压对硝化作用的影响

在气升式内循环硝化反应器中研究了渗透压对硝化作用的影响。保持进水氨氮浓度420mg·L-1,将进水渗透压逐渐从4.3×105Pa提高到18.8×105Pa,硝化反应器的氨氮转化率稳定在93%～100%。将进水渗透压进一步提高到19.2×105Pa,氨氮转化率降至69.2%。渗透压对硝化作用的影响具有突发性,临界值在18.8×105～19.2×105Pa之间。受高渗透压胁迫时,活性污泥中硝化细菌的形态趋向单一,个体变小,内膜数量减少,并产生许多不明成分的颗粒状内含物。解除渗透压胁迫后,细胞结构恢复。添加钾离子能够缓解高渗压对硝化作用的影响。高渗透压胁迫以及解除渗透压胁迫可增强污泥硝化活性,比污泥氨氮转化率(污泥以SS计)分别从0.083kg·kg-1·d-1升至0.509kg·kg-1·d-1和2.569kg·kg-1·d-1,同比提高5.1倍和30.0倍。     

Enhanced monoclonal antibody production by gradual increase of osmotic pressure

The time length required for the adaptation of AFP-27 hybridoma cells to high osmotic pressure and the effect of a gradual increase of osmotic pressure on monoclonal antibody production were investigated. When the cells were subjected to an increase of osmotic pressure from 300 mOsmol kg-1 to 366 mOsmol kg- 1, the intracellular content of osmoprotective free amino acids reached a maximum level 6 h after the osmotic pressure was increased to 366 mOsmol kg-1. The same time period of 6 h incubation at 366 mOsmol kg-1 was required to obtain a high growth rate of AFP-27 cells at 440 mOsmol kg-1 when the cells were subjected to a two-step increase of osmotic pressure from 300 mOsmol kg-1 to 366 mOsmol kg-1 and then to 440 mOsmol kg-1. The time length for the physiological adaptation of the cells to 366 mOsmol kg-1 was consequently estimated to be 6 h. Osmotic pressure during batch cultivation was gradually increased from 300 mOsmol kg-1 to 400 mOsmol kg-1 with an adaptation time of at least 6 h. The specific growth rates following a gradual increase of osmotic pressure were higher than those at a constant osmotic pressure of 400 mOsmol kg-1, while the specific monoclonal antibody production rate increased with the increase in the mean osmotic pressure. As a result, the cells grown under a gradual increase of osmotic pressure produced higher amounts of monoclonal antibodies than did those grown under constant osmotic pressure.     

Theoretical and experimental studies on freezing point depression and vapor pressure deficit as methods to measure osmotic pressure of aqueous polyethylene glycol and bovine serum albumin solutions

For survival in adverse environments where there is drought, high salt concentration or low temperature, some plants seem to be able to synthesize biochemical compounds, including proteins, in response to changes in water activity or osmotic pressure. Measurement of the water activity or osmotic pressure of simple aqueous solutions has been based on freezing point depression or vapor pressure deficit. Measurement of the osmotic pressure of plants under water stress has been mainly based on vapor pressure deficit. However, differences have been noted for osmotic pressure values of aqueous polyethylene glycol (PEG) solutions measured by freezing point depression and vapor pressure deficit. For this paper, the physicochemical basis of freezing point depression and vapor pressure deficit were first examined theoretically and then, the osmotic pressure of aqueous ethylene glycol and of PEG solutions were measured by both freezing point depression and vapor pressure deficit in comparison with other aqueous solutions such as NaCl, KCl, CaCl(2), glucose, sucrose, raffinose, and bovine serum albumin (BSA) solutions. The results showed that: (1) freezing point depression and vapor pressure deficit share theoretically the same physicochemical basis; (2) theoretically, they are proportional to the molal concentration of the aqueous solutions to be measured; (3) in practice, the osmotic pressure levels of aqueous NaCl, KCl, CaCl(2), glucose, sucrose, and raffinose solutions increase in proportion to their molal concentrations and there is little inconsistency between those measured by freezing point depression and vapor pressure deficit; (4) the osmotic pressure levels of aqueous ethylene glycol and PEG solutions measured by freezing point depression differed from the values measured by vapor pressure deficit; (5) the osmotic pressure of aqueous BSA solution measured by freezing point depression differed slightly from that measured by vapor pressure deficit.     

Effect of osmotic pressure on paclitaxel production in suspension cell cultures of Taxus chinensis

The effect of osmotic pressure on paclitaxel production was investigated in the suspension cell cultures of Taxus chinensis. Paclitaxel production was definitely influenced by the initial sucrose concentration and the highest production yield was achieved at the concentration of 60 g.l(-1) sucrose (300 mOsm.kg(-1)). High osmotic pressure conditions generated by non-metabolic sugar (mannitol and sorbitol) also enhanced paclitaxel production by about two-fold. Kinetic studies revealed that high initial osmotic pressure enhanced paclitaxel production and that high concentration of sucrose was effective for sustaining secondary metabolism after induction of paclitaxel biosynthesis. Stoichiometric analysis with different combinations of sucrose and mannitol confirmed that osmotic pressure was the more important factor for enhancing paclitaxel metabolism. The addition of non-sugar osmotic agent, PEG also enhanced paclitaxel production. In this paper, we showed that high osmotic pressure led to increases in paclitaxel production and proposed that regulation of osmotic pressure may be useful in controlling paclitaxel production.     

THE SWELLING AND OSMOTIC PRESSURE OF GELATIN IN SALT SOLUTIONS

1. The swelling and the osmotic pressure of gelatin at pH 4.7 have been measured in the presence of a number of salts. 2. The effect of the salts on the swelling is closely paralleled by the effect on the osmotic pressure, and the bulk modulus of the gelatin particles calculated from these figures is constant up to an increase in volume of about 800 per cent. As soon as any of the salts increase the swelling beyond this point, the bulk. modulus decreases. This is interpreted as showing that the elastic limit has been exceeded. 3. Gelatin swollen in acid returns to its original volume after removal of the acid, while gelatin swollen in salt solution does not do so. This is the expected result if, as stated above, the elastic limit had been exceeded in the salt solution. 4. The modulus of elasticity of gelatin swollen in salt solutions varies in the same way as the bulk modulus calculated from the osmotic pressure and the swelling. 5. The increase in osmotic pressure caused by the salt is reversible on removal of the salt. 6. The observed osmotic pressure is much greater than the osmotic pressure calculated from the Donnan equilibrium except in the case of AlCl₃, where the calculated and observed pressures agree quite closely. 7. The increase in swelling in salt solutions is due to an increase in osmotic pressure. This increase is probably due to a change in the osmotic pressure of the gelatin itself rather than to a difference in ion concentration.     

光棘豆悬浮细胞原生质体培养影响因素的研究

采用光棘豆无菌苗胚轴诱导的分化能力强的愈伤组织建立的胚必细胞悬浮系材料,对悬浮细胞原生质体解离所需酶液,原生质体培养所需要的渗透压和激素组合进行了研究。发现较低的培养基渗透压（〈０．３５ｍｏｌ／Ｌ葡萄糖）和较高浓度的２,４－Ｄ（〉１ｍｇ／Ｌ）易于诱导细胞出芽分裂,导致细胞破碎和死亡,并引起培养细胞褐化,找出适合光棘悬浮细胞原生质培养基渗透压和激素组合。     

Viability of Escherichia coli after combined osmotic and thermal treatment: a plasma membrane implication

This study investigates the influence of temperature (T) and osmotic pressure (Pi) on the viability of Escherichia coli K12 during an osmotic treatment. Osmotic shock (dehydration and rehydration within 1 s) in liquid media at different temperatures (4, 10, 30 and 37 degrees C) and different levels of osmotic pressure (26, 30, 35, 40, 82 and 133 MPa) were realized.Results show that a sudden dehydration, below 40 MPa, destroyed up to 80% of the bacterial population for each tested temperature, whereas viability was greater than 90% for an osmotic pressure less than 26 MPa. The influence of T and Pi on the membrane's physical structure is finally considered to explain the results in light of FTIR and electron microscopy study of the influence of temperature and osmotic pressure on E. coli membrane phospholipids conformation.     

Osmotic hemolysis and fragility A new model based on membrane disruption,and a potential clinical test

Red cell osmotic hemolysis has traditionally been defined by the loss of hemoglobin, in response to reduced osmotic pressure, as measured spectroscopically. Previous work from this laboratory using resistive pulse spectroscopy (RPS) has shown that in a mixed population of hemolyzing cell, ghosts can be detected as being more deformable, and hence appearing distinctly smaller, than the remaining intact cells. Other researchers using similar methods have reported detection of ghosts as apparently smaller objects, resulting from their greater sensitivity to dielectric breakdown. We now confirm both of these results, and demonstrate by kinetic studies that changes which occur in the rheological and electrical properties of ghosts are independent phenomena. We include in our analysis the explicit calculation of ghost and intact spherocyte resistivity after dielectric breakdown. The two different characterizations for ghosts are integrated into a proposed model of osmotic hemolysis based on known red blood cell membrane and cytoplasmic properties. This work provides both a theoretical and a practical foundation for RPS-based measures of osmotic fragility, including a potential new clinical test, measures which provide very early detection of the ultimate fate of osmotically stressed red cells.     

Investigating and modeling the combined effects of pH and osmotic pressure on seed germination for use in phytoactivity and allelopathic research

Phytoactivity and allelopathic studies are heavily dependent on germination bioassays of water solutions of allelochemical(s), which necessarily imply that pH and osmotic pressure vary among treatments and between treatments and controls and are therefore a confounding factor in the assessment of seed germination responses to allelochemical(s). When the contribution of pH and osmotic pressure to seed germination responses is considered in experimental designs their effects are almost without exceptions examined separately being assumed, without any evidences, that pH and osmotic pressure act independently on seed germination responses. The objectives of this work were to examine experimentally such assumption using wheat, lettuce, and subterranean clover cultivars to evaluate and model the combined effects on germination of pH and osmotic pressure in the range between 3.0–6.0 and 0–100 mOsmol kg^?1, respectively. Empirical equations are fitted, discussed, and the need to consider the simultaneous effects of pH and osmotic pressure firmly established. Finally, the use of the equations fitted and its impact on conclusions is exemplified in a dose-response bioassay of water extracts of Cistus ladanifer on seed germination using subterranean clover as target species where hormesis was found before allelochemical effects were corrected for pH and osmotic pressure values of control and extracts.     

Continuous measurement of protein osmotic pressure in blood and lymph of sheep

We have continuously measured protein osmotic pressure of blood and lymph in sheep to compare two kinds of needle osmometers (rigid and flexible) with a membrane osmometer (Wescor). We also compared the averaged values of the continuous measurement with osmotic pressure calculated from total protein and albumin fraction, using the Yamada equation. The rigid-needle and membrane osmometers showed excellent correlation (y = 1.00x + 0.06; r greater than 0.99). The flexible-needle osmometer tended to overestimate osmotic pressure (avg 16%). We used the rigid-needle osmometer for continuous measurements of protein osmotic pressure of blood and lymph in anesthetized or unanesthetized sheep to observe changes in protein osmotic pressure of blood and lymph through the three different interventions. The relationship between the theoretical values (x) and the continuous measurements (y) of osmotic pressure was good (y = 0.99x + 0.16, r = 0.97), but after various interventions, the continuously measured protein osmotic pressure tended to exceed the calculated measurements. The continuous measurement should be monitored with spot samples measured in a stationary osmometer or by calculation of osmotic pressure from total protein concentration and albumin fraction.     

Direct measurement of osmotic pressure of glycosaminoglycan solutions by membrane osmometry at room temperature

Articular cartilage is a hydrated soft tissue composed of negatively charged proteoglycans fixed within a collagen matrix. This charge gradient causes the tissue to imbibe water and swell, creating a net osmotic pressure that enhances the tissue's ability to bear load. In this study we designed and utilized an apparatus for directly measuring the osmotic pressure of chondroitin sulfate, the primary glycosaminoglycan found in articular cartilage, in solution with varying bathing ionic strength (0.015 M, 0.15 M, 0.5 M, 1 M, and 2 M NaCl) at room temperature. The osmotic pressure (pi) was found to increase nonlinearly with increasing chondroitin sulfate concentration and decreasing NaCl ionic bath environment. Above 1 M NaCl, pi changes negligibly with further increases in salt concentration, suggesting that Donnan osmotic pressure is negligible above this threshold, and the resulting pressure is attributed to configurational entropy. Results of the current study were also used to estimate the contribution of osmotic pressure to the stiffness of cartilage based on theoretical and experimental considerations. Our findings indicate that the osmotic pressure resulting from configurational entropy is much smaller in cartilage (based on an earlier study on bovine articular cartilage) than in free solution. The rate of change of osmotic pressure with compressive strain is found to contribute approximately one-third of the compressive modulus (H(A)(eff)) of cartilage (Pi approximately H(A)(eff)/3), with the balance contributed by the intrinsic structural modulus of the solid matrix (i.e., H(A) approximately 2H(A)(eff)/3). A strong dependence of this intrinsic modulus on salt concentration was found; therefore, it appears that proteoglycans contribute structurally to the magnitude of H(A), in a manner independent of osmotic pressure.     

破伤风抗毒素渗透压的质量控制标准

目的：通过对不同厂家破伤风抗毒素产品的渗透压浓度的调查,了解国内该产品的渗透压浓度的波动范围,为生产过程中渗透压浓度质量控制提供依据。方法采用Advanced 3250型冰点渗透压仪检测破伤风抗毒素的渗透压浓度。结果不同厂家破伤风抗毒素制品的渗透压浓度均不低于240 mOsmol/L。结论破伤风抗毒素渗透压浓度波动范围均与国外同类制品基本一致,符合欧洲药典规定。     

Water storage and osmotic pressure influences on the water relations of a dicotyledonous desert succulent

Abstract Water storage and nocturnal increases in osmotic pressure affect the water relations of the desert succulent Ferocactus acanthodes, which was studied using an electrical circuit analog based on the anatomy and morphology of a representative individual. Transpiration rates and osmotic pressures over a 24-h period were used as input variables. The model predicted water potential, turgor pressure and water flow for various tissues. Plant capacitances, storage resistances and nocturnal increases in osmotic pressure were varied to determine their role in the water relations of this dicotyledonous succulent. Water coming from storage tissues contributed about one-third of the water transpired at night: the majority of this water came from the nonphotosynthetic, water storage parenchyma of the stem. Time lags of 4 h were predicted between maximum transpiration and maximum water uptake from the soil. Varying the capacitance of the plant caused proportional changes in osmotically driven water movement but changes in storage resistance had only minor effects. Turgor pressure in the chlorenchyma depended on osmotic pressure, but was fairly insensitive to doubling or halving of the capacitance or storage resistance of the plant. Water uptake from the soil was only slightly affected by osmotic pressure changes in the chlorenchyma. For this stem succulent, the movement of water from the chlorenchyma to the xylem and the internal redistribution of water among stem tissues were dominated by nocturnal changes in chlorenchyma osmotic pressure, not by transpiration.     

The effect of the osmotic pressure of the culture medium on cells of Francisella tularensis vaccinal strain 15

The dependence of the growth rate of F. tularensis on the osmotic properties of the medium can be presented as a curve with the maximum in the area of 500-600 mOsm. Under these circumstances the intracellular osmotic pressure exceeds the extracellular one by 50-100 mOsm. With the rise of the osmotic pressure in the medium the increase of the concentration of K+ in the cells occurs. The energy-dependent accumulation of K+ in the cells at rest is activated by the rise of the osmotic pressure in the medium. F. tularensis are probably capable of osmoregulation, ensured by the energy-dependent osmosensitive K(+)-transporting system.     

DONNAN EQUILIBRIUM AND THE PHYSICAL PROPERTIES OF PROTEINS : II. OSMOTIC PRESSURE.

1. It had been shown in previous publications that the osmotic pressure of a 1 per cent solution of a protein-acid salt varies in a characteristic way with the hydrogen ion concentration of the solution, the osmotic pressure having a minimum at the isoelectric point, rising steeply with a decrease in pH until a maximum is reached at pH of 3.4 or 3.5 (in the case of gelatin and crystalline egg albumin), this maximum being followed by a steep drop in the osmotic pressure with a further decrease in the pH of the gelatin or albumin solution. In this paper it is shown that (aside from two minor discrepancies) we can calculate this effect of the pH on the osmotic pressure of a protein-acid salt by assuming that the pH effect is due to that unequal distribution of crystalloidal ions (in particular free acid) on both sides of the membrane which Donnan''s theory of membrane equilibrium demands. 2. It had been shown in preceding papers that only the valency but not the nature of the ion (aside from its valency) with which a protein is in combination has any effect upon the osmotic pressure of the solution of the protein; and that the osmotic pressure of a gelatin-acid salt with a monovalent anion (e.g. Cl, NO₃, acetate, H₂PO₄, HC₂O₄, etc.) is about twice or perhaps a trifle more than twice as high as the osmotic pressure of gelatin sulfate where the anion is bivalent; assuming that the pH and gelatin concentrations of all the solutions are the same. It is shown in this paper that we can calculate with a fair degree of accuracy this valency effect on the assumption that it is due to the influence of the valency of the anion of a gelatin-acid salt on that relative distribution of the free acid on both sides of the membrane which Donnan''s theory of membrane equilibrium demands. 3. The curves of the observed values of the osmotic pressure show two constant minor deviations from the curves of the calculated osmotic pressure. One of these deviations consists in the fact that the values of the ascending branch of the calculated curves are lower than the corresponding values in the curves for the observed osmotic pressure, and the other deviation consists in the fact that the drop in the curves of calculated values occurs at a lower pH than the drop in the curves of the observed values.     

Antagonistic effects of hydrostatic pressure and osmotic pressure on cytochrome P-450cam spin transition.

The combined effects of hydrostatic pressure and osmotic pressure, generated by polyols, on the spin equilibrium of fenchone-bound cytochrome P-450cam were investigated. Hydrostatic pressure indices a high spin to low spin transition, whereas polyols induce the reversed reaction. Of the four solutes used, glycerol, glucose, stachyose, and sucrose, only the last two would act on the spin transition by osmotic stress. The spin volume changes measured by both techniques are different, 29 and -350 ml/mol for hydrostatic pressure and osmotic pressure, respectively. It suggests that even if the two are perturbing water molecules, different properties are probed. From the volume change induced by osmotic stress, 19 water molecules are deduced that would be implicated in the spin transition of the fenchone-bound protein. This result suggests that water molecules other than the well defined ones located in the active site play a key role in modulating the spin equilibrium of cytochrome P-450cam.     

Changes in osmotic and turgor pressure in response to sugar accumulation in barley source leaves

Pressure-probe measurements and single-cell sampling and analysis techniques were used to determine the effect of photosynthetic production and accumulation of sugars on osmotic and turgor pressures of individual cells of barley ( Hordeum vulgare L.) source leaves. In control plants, the changes in osmotic pressure in individual cells during the photoperiod were different for mesophyll (increase of 276 mOsmol/kg), parenchymatous bundle sheath (PBS; increase of 100 mOsmol/kg) and epidermis (remains constant). There was also an increase in osmotic pressure at the tissue level. Cooling of roots and the shoot apical meristem restricted the export of sugars from leaves, and the resulting changes in osmotic and turgor pressure were monitored. In contrast to the control leaves, mesophyll, PBS, and epidermal cells showed a similar increase in osmotic pressure (up to 500 mOsmol/kg). Cooling also increased the turgor pressure in epidermal and (to a greater extent) PBS cells. The difference in turgor pressure between epidermal and PBS cells is consistent with the presence of a water potential gradient within the leaf, from the vascular bundles towards the leaf surface.     

Proteins induced by high osmotic pressure in Escherichia coli

Abstract The protein composition of Escherichia coli grown under conditions of high and low osmotic pressure and following shifts from one condition to the other was examined by two-dimensional gel electrophoresis. Upon shift to high osmotic pressure there is a rapid induction of a group of proteins whose synthesis persists during prolonged growth at elevated osmotic pressure. An osmotic down-shift results in the repression of these proteins. Neither shift induced the heat shock regulon.     

Osmotic relations during elongation growth in hypocotyls of Helianthus annum L.

The relationship between growth, change in cell osmotic pressure and accumulation of osmotic solutes was investigated in hypocotyls of sunflower (Helianthus annum L.) seedlings. During growth in darkness the osmotic pressure decreased by 50% between days 2 and 6 after sowing. After irradiation of dark-grown seedlings with continuous white light (WL) an inhibition of hypocotyl growth was measured, but the osmotic pressure of the growing cells was not lower than in the dark-grown control. Growth in darkness and after WL irradiation was accompanied by an increase in the amount of osmotic substances (soluble sugars) which was proportional to the increase in length of the organ. During growth in continuous WL the cell osmotic pressure decreased by 45 % between days 2 and 6 after sowing. The transfer of WL-grown seedlings to darkness (“re-etiolation”) resulted in a rapid acceleration of hypocotyl growth, but the cell osmotic pressure was the same as that of the WL grown control. Growth in continuous WL was accompanied by a corresponding accumulation of osmotic substances (soluble sugars). The transition from WL to darkness resulted in an enhanced accumulation of osmotica and an increase in cell-wall extensibility. The results indicate that the relative maintenance of cell osmotic pressure during rapid hypocotyl growth in darkness is caused by an enhanced accumulation of soluble sugars into the growing cells of the organ.