A SEAWATER MEDIUM FOR DINOFLAGELLATES AND THE NUTRITION OF CACHONINA NIEI1

Two media have been devised: an enriched seawater medium for culture of dinoflagellates and a defined medium for rapid growth of the dinoflagellate Cachonina niei. A wide range in salinity (10.23–42.38 g/liter NaCl) is tolerated by C. niei. Below 0.6 g/liter MgSO₄, 0.19 g/liter KCl, and 0.22 g/liter CaCl₂, the generation time greatly increases. Increase in MgSO₄ to 7.22 g/liter, KCl to 1.12 g/liter or CaCl₂ to 2.22 g/liter has little effect on generation time. The temperature optimum is 19–23 C. Saturating light intensity for growth is 1000 ft-c and for photosynthesis (determined manometrically) is slightly less than 2000 ft-c. Cachonina niei requires B₁₂ and thiamin. Neither silicate nor its competitive inhibitor germanate affects generation time or cell yield indicating silicon is not required. Of a variety of buffers tested, Tris is the best. Optimal growth occurs at pHs of 7.5–8.3. Glycerol is inhibitory and does not support dark growth.     

THE EFFECT OF CERTAIN ELECTROLYTES AND NON-ELECTROLYTES ON PERMEABILITY OF LIVING CELLS TO WATER

1. Permeability to water in unfertilized eggs of the sea urchin, Arbacia punctulata, is found to be greater in hypotonic solutions of dextrose, saccharose and glycocoll than in sea water of the same osmotic pressure. 2. The addition to dextrose solution of small amounts of CaCl₂ or MgCl₂ restores the permeability approximately to the value obtained in sea water. 3. This effect of CaCl₂ and MgCl₂ is antagonized by the further addition of NaCl or KCl. 4. It is concluded that the NaCl and KCl tend to increase the permeability of the cell to water, CaCl₂ and MgCl₂ to decrease it. 5. The method here employed can be used for quantitative study of salt antagonism.     

MICRURGICAL STUDIES IN CELL PHYSIOLOGY : I. THE ACTION OF THE CHLORIDES OF NA,K, CA,AND MG ON THE PROTOPLASM OF AM?BA PROTEUS.

By means of micro-dissection and injection Amœba proteus was treated with the chlorides of Na, K, Ca, and Mg alone, in combination, and with variations of pH. I. The Plasmalemma. 1. NaCl weakens and disrupts the surface membrane of the ameba. Tearing the membrane accelerates the disruption which spreads rapidly from the site of the tear. KCl has no disruptive effect on the membrane but renders it adhesive. 2. MgCl₂ and CaCl₂ have no appreciable effect on the integrity of the surface membrane of the ameba when applied on the outside. No spread of disruption occurs when the membrane is torn in these salts. When these salts are introduced into the ameba they render the pellicle of the involved region rigid. II. The Internal Protoplasm. 3. Injected water either diffuses through the protoplasm or becomes localized in a hyaline blister. Large amounts when rapidly injected produce a "rushing effect". 4. HCl at pH 1.8 solidifies the internal protoplasm and at pH 2.2 causes solidification only after several successive injections. The effect of the subsequent injections may be due to the neutralization of the cell-buffers by the first injection. 5. NaCl and KCl increase the fluidity of the internal protoplasm and induce quiescence. 6. CaCl₂ and MgCl₂ to a lesser extent solidify the internal protoplasm. With CaCl₂ the solidification tends to be localized. With MgCl₂ it tends to spread. The injection of CaCl₂ accelerates movement in the regions not solidified whereas the injection of MgCl₂ induces quiescence. III. Pinching-Off Reaction. 7. A hyaline blister produced by the injection of water may be pinched off. The pinched-off blister is a liquid sphere surrounded by a pellicle. 8. Pinching off always takes place with injections of HCl when the injected region is solidified. 9. The injection of CaCl₂ usually results in the pinching off of the portion solidified. The rate of pinching off varies with the concentration of the salt. The injection of MgCl₂ does not cause pinching off. IV. Reparability of Torn Surfaces. 10. The repair of a torn surface takes place readily in distilled water. In the different salt solutions, reparability varies specifically with each salt, with the concentration of the salt, and with the extent of the tear. In NaCl and in KCl repair occurs less readily than in water. In MgCl₂ repair takes place with great difficulty. In CaCl₂ a proper estimate of the process of repair is complicated by the pinching-off phenomenon. However, CaCl₂ is the only salt found to increase the mobility of the plasmalemma, and this presumably enhances its reparability. 11. The repair of the surface is probably a function of the internal protoplasm and depends upon an interaction of the protoplasm with the surrounding medium. V. Permeability. 12. NaCl and KCl readily penetrate the ameba from the exterior. CaCl₂ and MgCl₂ do not. 13. All four salts when injected into an ameba readily diffuse through the internal protoplasm. In the case of CaCl₂ the diffusion may be arrested by the pinching-off process. VI. Toxicity. 14. NaCl and KCl are more toxic to the exterior of the cell than to the interior, and the reverse is true for CaCl₂ and MgCl₂. 15. The relative non-toxicity of injected NaCl to the interior of the ameba is not necessarily due to its diffusion outward from the cell. 16. HCl is much more toxic to the exterior of a cell than to the interior; at pH 5.5 it is toxic to the surface whereas at pH 2.5 it is not toxic to the interior. NaOH to pH 9.8 is not toxic either to the surface or to the interior. VII. Antagonism. 17. The toxic effects of NaCl and of KCl on the exterior of the cell can be antagonized by CaCl₂ and this antagonism occurs at the surface. Although the lethal effect of NaCl is thus antagonized, NaCl still penetrates but at a slower rate than if the ameba were immersed in a solution of this salt alone. 18. NaCl and HCl are mutually antagonistic in the interior of the ameba. No antagonism between the salts and HCl was found on the exterior of the ameba. No antagonism between the salts and NaOH was found on the interior or exterior of the ameba. 19. The pinching-off phenomenon can be antagonized by NaCl or by KCl, and the rate of the retardation of the pinching-off process varies with the concentration of the antagonizing salt. 20. The prevention of repair of a torn membrane by toxic solutions of NaCl or KCl can be antagonized by CaCl₂. These experiments show directly the marked difference between the interior and the exterior of the cell in their behavior toward the chlorides of Na, K, Ca, and Mg.     

COMPARATIVE STUDIES ON RESPIRATION : VIII. THE RESPIRATION OF BACILLUS SUBTILIS IN RELATION TO ANTAGONISM.

1. In relatively low concentrations of NaCl, KCl, and CaCl₂ the rate of respiration of Bacillus subtilis remains fairly constant for a period of several hours, while in the higher concentrations, there is a gradual decrease in the rate. 2. NaCl and KCl increase the rate of respiration of Bacillus subtilis somewhat at concentrations of 0.15 M and 0.2 M respectively; in sufficiently high concentrations they decrease the rate. CaCl₂ increases the rate of respiration of Bacillus subtilis at a concentration of 0.05 M and decreases the rate at somewhat higher concentrations. 3. The effects of salts upon respiration show a well marked antagonism between NaCl and CaCl₂, and between KCl and CaCl₂. The antagonism between NaCl and KCl is slight and the antagonism curve shows two maxima.     

CALCULATIONS OF BIOELECTRIC POTENTIALS : IV. SOME EFFECTS OF CALCIUM ON POTENTIALS IN NITELLA

In Nitella the substitution of KCl for NaCl changes the P.D. in a negative direction. In some cases this change is lessened by adding solid CaCl₂ to the solution of KCl. This may be due to lessening the partition coefficient of KCl or to decreasing the solubility of an organic substance which sensitizes the cell to the action of KCl. Little or no correlation exists between this effect of calcium and its ordinary antagonistic action in producing a balanced solution which preserves the life of the cell indefinitely. CaCl₂ is negative to NaCl but positive to KCl. The effects of mixtures of KCl, NaCl, and CaCl₂ are discussed. The concentration effect of a mixture of KCl + CaCl₂ shows certain peculiarities due to action currents: these resemble those found with pure KCl. These studies and others on Nitella, Valonia, and Halicystis indicate that mobilities and partition coefficients are variable and can be brought under experimental control.     

Influence des pretraitements par KCl et des rapports Ca/Na du milieu sur la croissance de vitroplants de tomate en milieu NaCl

The 18-day-old tomato vitroplants were obtained in axenic conditions by culture of expiants (including the terminal bud and the last internode of the stem) on agar-agar nutritive medium with 0 or 75 mM NaCl. The growth and the mineral content of the vitroplants were compared when the expiants were grown on media either with low or high K/Na and Ca/Na ratios, or with low K/Na and Ca/Na ratios after pretreatments of expiants by KC1, NaCl or CaCl₂ (from 0 to – 4.5 bar). The KCl pretreatment (-1.1 bar) during one day brings about an increase in vitroplant growth greater than that produced by a high Ca/Na ratio medium. The Cl accumulation was similar in expiants pretreated by KCl or NaCl. Ion content per gram of fresh matter was similar in 18-day-old vitroplants pretreated by KCl, NaCl or CaCl₂; the Na accumulation by KC1 pretreated vitroplants was not lower than that of 18-day-old vitroplants grown on a high Ca/Na ratio medium. These results show the relation between Na content of expiants and the growth of vitroplants in a NaCl medium.     

COMBINATION OF SALTS AND PROTEINS : III. THE COMBINATION OF CuCl2, MgCl2, CaCl2, AlCl3, LaCl3, KCl,AgNO3AND Na2SO4WITH GELATIN.

1. The combination of Cu⁺⁺, Ca⁺⁺, Mg⁺⁺, Al⁺⁺⁺, La⁺⁺⁺, K⁺, Ag⁺, and Cl^- with gelatin has been determined. 2. The equivalent combining value for copper is about 0.9 millimols per gm. of gelatin and is therefore the same as that of hydrogen. The value for copper with deaminized gelatin is about 0.4 to 0.5, again the same as that of hydrogen. The sum of the hydrogen and copper ions combined in the presence of an excess of either is 0.9 millimols showing that there is an equilibrium between the copper hydrogen and gelatin and that the copper and hydrogen are attached to the same group. 3. The equivalent combining value of La⁺⁺⁺ and Al⁺⁺⁺ is about 0.5 millimols per gm. of gelatin. This value is not significantly different with deaminized gelatin so that it is possible these salts combine only with groups not affected by deaminization. 4. No calcium is combined on the acid side of pH 3. The value rises rapidly from pH 3 to 4.7 and then remains constant. 5. No combination of K, Li, Na, NO₃ or SO₄ could be detected. 6. Cl combines less than the di- and trivalent metals so that the protein is positive in CaCl₂ but negative in KCl.     

ELECTROKINETICS : XVII. SURFACE CHARGE AND ION ANTAGONISM

1. The question of the critical pore diameter for streaming potential is discussed. 2. The surface charge is calculated for cellulose in contact with solutions of K₃PO₄, K₂CO₃, K₂SO₄, KCl, and ThCl₄. 3. The surface charge of cellulose in contact with a solution of 2 x 10^–4 N NaCl is calculated as a function of temperature and is found to show a sharp break at 39°. This is interpreted in terms of the change of the specific heat of water. 4. A marked ion antagonism is found in NaCl:KCl, KCl:MgCl₂, NaCl:MgCl₂, NaCl:CaCl₂, KCl:CaCl₂, CaCl₂:MgCl₂ mixtures when the surface charge is calculated as a function of concentration.     

Effect of the cations sodium,potassium and calcium on the interaction of hyaluronate chains: a light scattering and viscometric study

Light scattering and viscometric studies have been carried out on two preparations, A and B, of rooster comb hyaluronate. Sedimentation rate studies have also been performed with A. Light scattering measurements in 0.2 m KCl for preparation A gave a molecular weight of 3.3 × 10⁶ and for B, 1.0 × 10⁶. In (0.1–0.3) M NaCl similar measurements gave a particle weight for A of (4.4–6.4 × 10⁶ and for B (1.7–2.8 × 10⁶. In 0.066 m CaCl₂ molecular weight values of 9.5 × 10⁶ for A and 1.7 × 10⁶ for B were obtained. Thus in the presence of Na⁺ and Ca²⁺ ions aggregates of chains persisted into dilute solution. Measurements by light scattering on A and B in 4 m guanidinium chloride gave values in the same range as those obtained in 0.2 m KCl. Sedimentation rate studies on A gave values of 10.3 Svedbergs in 0.2 m KCl and 12.2 Svedbergs in 0.2 m NaCl and 0.066m CaCl₂. The shear dependence of the viscosity was studied using a conicylindrical viscometer at shear rates between 0.5 and 20 s^?1. Preparation A in 0.2 m KCl and NaCl yielded values for (ν_sp/cc→0 of 5000 and 7100 ml g^?1 respectively in keeping with the tendency to aggregate. The behaviour for preparation B was similar. In 0.066 m CaCl₂ there was a marked dependence of viscosity on shear speed below 10 s^?1 for all concentrations and the value of (ν_sp/c)→0 at 0 s^?1 for preparation A was 7700 ml g^?1 while at a shear rate of 8 s^?1 (ν_sp/c)c→0 ? 5000 ml g ^?1. Similar effects were found for preparation B and the data suggest associations of chains disruptable by weak shear forces. The increase in viscosity with concentration in the presence of 0.066 m CaCl₂ was much less than in the presence of KCl or NaCl, suggesting that the Ca²⁺ had a marked effect on the ”rigidity’ of the molecules in solution. A viscometric titration experiment with Ca^2? showed that a level of 0.02 m CaCl₂ in 0.2 m NaCl was sufficient to produce the change in viscosity presented above and that significant perturbations of the viscosity were present at 0.005?0.01 m CaCl₂.     

CHEMICAL ANTAGONISM OF IONS : IV. EFFECT OF SALT MIXTURES ON GLYCINE ACTIVITY.

The pH of a 0.01 molar solution of glycine, half neutralized with NaOH, is 9.685. Addition of only one of the salts NaCl, KCl, MgCl₂, or CaCl₂ will lower the pH of the solution (at least up to 1 µ). If a given amount of KCl is added to a glycine solution, the subsequent addition of increasing amounts of NaCl will first raise the pH (up to 0.007 M NaCl). Further addition of NaCl (up to 0.035 M NaCl) will lower the pH, and further additions slightly raise the pH. The same type of curve is obtained by adding NaCl to glycine solution containing MgCl₂ or CaCl₂ except that the first and second breaks occur at 0.015 M and 0.085 M NaCl, respectively. Addition of CaCl₂ to a glycine solution containing MgCl₂ gives the same phenomena with breaks at 0.005 M and 0.025 M CaCl; or at ionic strengths of 0.015 µCaCl₂ and 0.075 µCaCl₂. This indicates that the effect is a function of the ionic strength of the added salt. These effects are sharp and unmistakable. They are almost identical with the effects produced by the same salt mixtures on the pH of gelatin solutions. They are very suggestive of physiological antagonisms, and at the same time cannot be attributed to colloidal phenomena.     

I. THE RELATION BETWEEN ATTACHMENT TO THE SUBSTRATUM AND INGESTION BY AMEBA IN STRYCHNINE SULFATE SOLUTION AND CONDITIONED MEDIA : II. BIOLOGICAL ASSAY OF CONDITIONED MEDIA

1. Strychnine sulfate 0.000069 M decreased percentage attachment to the substratum by Amoeba proteus in 0.0029 M NaCl from 77.3 to 1.3, in 0.0029 M KCl from 40.8 to 2.5, in 0.002 M CaCl₂ from 73.3 to 68.0, in 0.002 M MgCl₂ from 85.5 to 83.3. 2. Frequency of ingestion of chilomonads by Amoeba proteus is increased by adding strychnine sulfate to solutions of NaCl, KCl, or CaCl₂. Frequency of ingestion is increased in NaCl solution from 1.3 to 2.3, in KCl from 0.75 to 2.25, and in CaCl₂ from 1.1 to 1.9 chilomonads per minute. Ingestion is not significantly increased by the addition of strychnine to MgCl₂ solution. 3. Frequency of ingestion of food by Amoeba proteus is not closely correlated with attachment to the substratum in NaCl and KCl solutions to which strychnine sulfate is added. 4. Chilomonads adhere to the plasmalemma of Amoeba proteus in solutions of NaCl, KCl, or CaCl₂ containing strychnine, but in MgCl₂ plus strychnine only a few adhere to it. Strychnine appears to make the surface of the amebae and chilomonads sticky in the former but not in the latter. Frequency of ingestion is apparently correlated with adherence of chilomonads to the plasmalemma. 5. Attachment to the substratum and ingestion by Pelomyxa carolinensis is increased by dead Chilomonas, Colpidium, and Paramecium in aqueous solutions, by materials obtained from paramecia by alcoholic-ether extraction, and by solutions in which these organisms have lived. 6. Attachment to the substratum by Pelomyxa carolinensis is not closely correlated with kind or concentration of inorganic salts used in this study. 7. Materials were found in extracts of paramecia which had certain characteristics in common with choline esters. There is no reason to doubt that under certain conditions materials are present in aqueous and alcoholic extracts which are pharmacologically similar to choline and acetylcholine. 8. Aqueous suspensions of paramecia when subcutaneously injected into young mice for 21 days inhibit the gonadotropic luteinizing hormone of the pituitary. Ovaries from injected mice showed no corpora lutea, and the seminal vesicles from injected males were smaller and contained less fluid than those of the controls.     

Effect of sodium,potassium, and calcium ions on electroreceptor function in catfish

Impulses from single electroreceptors (small pit organs) of catfish (Ictalurus nebulosus) were recorded during stimulation by square pulses. Solutions with different concentrations of potassium, sodium, and calcium ions were applied to the pore of the receptor. Solutions with a low CaCl₂ concentration did not alter the responses of the receptor. Calcium ions in concentrations of over 5 mM increased the threshold of the response to electrical stimulation. The threshold to anodal stimulation was increased in solutions of 2 mM sodium and potassium and no response was given to a cathodal stimulus. The effect of 2 mM solutions of NaCl and KCl was abolished by the addition of 0.4 mM CaCl₂ or by application of a long anodal stimulus of high intensity (10⁻⁸∓10⁻⁷ A/mm²). Increasing the potassium ion concentration to 10–20 mM restored normal receptor function but a further increase led to elevation of the threshold. The action of an electric current is compared with the action of the ions.     

Permeability of Bacteria to Inorganic Cations. A Comparison between a Psychrophilic Achromobacter Strain and Escherichia coli

The permeability of a psychrophilic Acbromobacter strain to the chlorides of Na, K, Mg and Ca was investigated with light-scattering technique. Comparisons, were made with cells of Escherichia coli B. Cells of both strains suspended in “water were plasmolyzed by 0.1 or 0.2 M solutions of MgCl₂ or CaCl₂ without subsequent deplasmolysis. NaCl or KCl also plasmolyzed the cells, but deplasmolysis followed.” When suspended in growth medium E. coli became completely de-plasmolyzed., whereas the psychrophile still excluded MgCl₂ and CaCl₂ to a great extent. The plasmolysis and deplasmolysis were reversible. Electron micrographs of the psychrophile exposed to CaCl₂ confirmed the presence of plasrnolysis.     

SODIUM CHLORIDE AND SELECTIVE DIFFUSION IN LIVING ORGANISMS

1. It is shown that NaCl acts like CaCl₂ or LaCl₃ in preventing the diffusion of strong acids through the membrane of the egg of Fundulus with this difference only that a M/8 solution of NaCl acts like a M/1,000 solution of CaCl₂ and like a M/30,000 solution of LaCl₃. 2. It is shown that these salts inhibit the diffusion of non-dissociated weak acid through the membrane of the Fundulus egg but slightly if at all. 3. Both NaCl and CaCl₂ accelerate the diffusion of dissociated strong alkali through the egg membrane of Fundulus and CaCl₂ is more efficient in this respect than NaCl. 4. It is shown that in moderate concentrations NaCl accelerates the rate of diffusion of KCl through the membrane of the egg of Fundulus while CaCl₂ does not.     

Ions and osmolality on post‐thaw sperm motility activation of the endangered Brycon insignis (Characiformes)

The aim of this study was to evaluate the effects of osmolality and the presence of ions on the activation of post‐thaw sperm motility of Brycon insignis. Sperm was frozen under a standardized methodology for this species. In experiment 1, 11 solutions were prepared with reverse osmosis (RO) water (～0 mOsm/kg) and glucose or NaCl adjusted to an osmolality of 50, 100, 150, 200 and 250 mOsm/kg. In experiment 2, six solutions were prepared with RO and adjusted to ~100 mOsm/kg with one of the following chemicals: NaHCO₃, sodium citrate (Na₃C₆H₅O₇), NaCl, KCl, CaCl₂ or glucose (as ion‐free control). Post‐thaw sperm of both experiments was evaluated for motility rate, velocities (curvilinear = VCL, among others) and beat‐cross frequency (BCF). In experiment 1, sperm motility rate and velocities were higher (p < 0.05) when triggered in solutions at osmolalities from 0 to 200 mOsm/kg (62–80% motility; 139–167 µm/s) than that at 250 mOsm/kg (36–44% motility; 94–99 µm/s VCL). BCF was not affected by osmolality and varied from 19 to 24 Hz in all samples. In experiment 2, samples activated in NaHCO₃, citrate, NaCl and KCl solutions yielded higher motility rates (76–85%) and BCF (24–25 Hz) compared to those activated in CaCl₂ (50%; 14 Hz). Samples activated in ion‐free control solution yielded higher motility rate (87%) than those activated in NaHCO₃ and in CaCl₂. Curvilinear velocity was higher in samples activated in NaHCO₃, citrate, KCl and control solutions (144–160 µm/s) than in those activated in CaCl₂ (104 µm/s); samples activated in NaCl yielded intermediate VCL values (127 µm/s). Post‐thaw sperm achieves maximum motility rate and velocities when activated in solutions composed of sodium citrate, NaCl, KCl or glucose. Thus, post‐thaw sperm motility of B. insignis can be triggered in ionic and non‐ionic solutions at osmolality between 0 and 200 mOsm/kg. The use of solutions containing calcium, however, should be avoided.     

Ethylene and ethane production in response to salinity stress

Abstract Ethylene and ethane production in mung bean hypocotyl sections were evaluated as possible indicators of stress due to contact with four salts that are common in natural sites. Ethylene production decreased with increasing concentrations of applied NaCl and KCl. When CaCl₂ was applied, the ethylene evolution was greater. However, when MgCl₂ was applied, ethylene evolution remained high then decreased and at higher salt concentrations again showed an increase. NaCl (up to 0.1 kmol m^?1) and KCl (up to 0.5 kmol m^?3) caused a concentration-dependent increase in ethane production. The ethane production with CaCl₂ was the lowest among the salts tested and only a minute increase was noticed with the increase of concentration from 0.01 to 1 kmol m^?3. Ethane production showed a distinct maximum at 0.2 kmol m^?3 MgCl₂. The introduction of 0.01 kmol m^?3 CaCl₂, as well as anaerobic conditions obtained by purging vials with N₂, eliminated that high ethane production. Respiratory activity of the mung bean hypocotyl sections in MgCl₂ concentrations from 0 to 0.5 kmol m^?3 was correlated with ethane but not with ethylene production. The ethane/ethylene ratio showed three patterns for the four salts tested.     

MICRURGICAL STUDIES IN CELL PHYSIOLOGY : V. THE ANTAGONISM OF CATIONS IN THEIR ACTIONS ON THE PROTOPLASM OF AM?BA DUBIA.

I. The Plasmalemma. 1. On the plasmalemma of amebæ CaCl₂ antagonizes the toxic action of LiCl better than it does NaCl, and still better than it does KCl. MgCl₂ antagonizes the toxic action of NaCl better than it does LiCl and still better than it does KCl. 2. CaCl₂ antagonizes the toxic action of LiCl and of KCl better than does MgCl₂: MgCl₂ antagonizes NaCl better than does CaCl₂. II. The Internal Protoplasm. 3. The antagonizing efficiency of CaCl₂ and of MgCl₂ are highest against the toxic action of KCl on the internal protoplasm, less against that of NaCl, and least against that of LiCl. 4. CaCl₂ antagonizes the toxic action of LiCl better than does MgCl₂: MgCl₂ antagonizes the toxic action of NaCl and of KCl better than does CaCl₂. 5. LiCl antagonizes the toxic action of MgCl₂ on the internal protoplasm more effectively than do NaCl or KCl, which have an equal antagonizing effect on the MgCl₂ action. III. The Nature of Antagonism. 6. When the concentration of an antagonizing salt is increased to a toxic value, it acts synergistically with a toxic salt. 7. No case was found in which a potentially antagonistic salt abolishes the toxic action of a salt unless it is present at the site (surface or interior) of toxic action. 8. Antagonistic actions of the salts used in these experiments are of differing effectiveness on the internal protoplasm and on the surface membrane.     

Differential response of two almond rootstocks to chloride salt mixtures in the growing medium

It was examined how essential cations, Ca²⁺ and K⁺, can mitigate the toxic effects of NaCl on two different almond species (Prunus amygdalus Batsch) rootstocks, Garnem (GN15) and Bitter Almond. The tree growth parameters (water potential (Ψ_w), gas exchange, nutrient uptake) and leaf chlorophyll (Chl) content were measured in control and NaCl-treated plants with or without KCl or CaCl₂ supplements. The addition of CaCl₂ and KCl to Bitter Almond trees reduced their dry weight, shoot growth and leaf number although net photosynthetic assimilation rate (A) was not affected. These results indicated that changing of photo-assimilates flux to proline and/or soluble sugars synthesis may help to increase leaf Ψ_w. The Garnem trees also did not respond to the CaCl₂ and KCl addition indicating that the plants are already getting enough of these two cations (C^a2+ and K⁺). In both rootstocks, NaCl in the medium reduced growth attributes, Ψ_w, A, stomatal conductance (g_s), and leaf Chl content. When CaCl₂ and KCl fertilizers were added together with NaCl to Bitter Almond trees, leaf K⁺ and Ca²⁺ contents increased while Na⁺ and Cl^– decreased leading to higher Ca/Na and K/Na ratios, but shoot growth was not improved and even declined compared to NaCl-treated trees. It appears that the addition of salts further aggravated osmotic stress as indicated by the accumulation of proline and soluble sugars in leaf tissues. The addition of KCl or CaCl₂ to NaCl-treated GN15 trees did not increase A, leaf Ψ_w, and shoot growth but improved ionic balances as indicated by higher Ca/Na and K/Na ratios. The reduction in A was mainly due to non-stomatal limitations in GN15, possibly due to the degradation of Chl a, unlike Bitter Almond, for which the reduction of A was due to stomata closure. The improvement in ionic balances and water status of Bitter Almond trees in response to addition of KCl or CaCl₂ was apparently offset by a high sensitivity to Cl^–; therefore, no-chloride salts should be the preferred forms of fertilizers for this rootstock. Both rootstocks were sensitive to soil salinity and cation supplements were of limited value in mitigating the effect of excessive salt concentrations.     

EFFECT OF SALINITY ON POLLEN I. POLLEN VIABILITY AS ALTERED BY INCREASING OSMOTIC PRESSURE WITH NaCl,MgCl2, and CaCl2

Petunia (Petunia hybrida Vilm. cv. ‘Snowstorm') plants were grown in saline solution (NaCl, MgCl₂, and/or CaCl₂) of 0, 1, 2, and 3 bars osmotic pressures. Pollen viability was tested by tetrazolium chloride staining and by germination (by the hanging drop method, using 15 % sucrose and 0.01 % boric acid as the nutrient medium, at 27 ± 1 C). Pollen viability decreased with increased salinity. Pollen from plants grown in single salt solutions of NaCl, MgCl₂, and CaCl₂ (each at 0, 1, 2, or 3 bars osmotic pressure) was germinated in base culture medium. Pollen viability decreased more with NaCl than with MgCl₂ or CaCl₂. In vitro studies of the effects of three salts, viz., NaCl, MgCl₂, and CaCl₂, on pollen germination and tube growth showed that NaCl inhibited germination and pollen tube growth more than did MgCl₂ or CaCl₂. MgCl₂ was least injurious, and even promoted tube growth at 0.5 and 0.75 bars osmotic pressure. Adding low concentrations of MgCl₂ reduced the toxic effect of NaCl and increased the percentage of germination. CaCl₂ reduced the effect of NaCl less than did MgCl₂. We conclude that specific ion effects were more important than osmotic pressure.     

Influence of Electrolytes on the Thicknesses of the Phospholipid Bilayers of Lamellar Lecithin Mesophases

Over a wide range of water contents, aqueous lecithin-water mixtures are mesophases in which lecithin bilayers alternate with water layers. This paper reports on low-angle X-ray diffraction measurements of the effects of electrolytes, at 1.0 N concentration, on the thicknesses of the bilayers in mesophases formed by the synthetic lecithin: 1-octadec-9-enyl-2-hexadecylglycerophosphocholine. With solutions of LiCl, NaCl, Na₂SO₄, KCl, and CsCl, the bilayer thicknesses are less than with pure water. The maximum reduction in bilayer thickness with these electrolytes is about 10% and occurs with mesophases of high content of KCl and CsCl solutions. With HCl solutions the bilayer thicknesses are about 5% greater than with pure water, and with CaCl₂ solutions the bilayer thicknesses are about the same as with pure water. The maximum amount of solution which can be mixed with lecithin before a second, purely aqueous phase is formed is also affected by electrolytes, the order for the various 1.0 N solutions being CsCl = KCl > NaCl > Na₂SO₄ > (pure water) = LiCl > CaCl₂.