EFFECTS OF HYDROXYL ON NEGATIVE AND POSITIVE CELLS OF NITELLA

Remarkable changes are brought about by KOH in transforming negative cells of Nitella (showing dilute solution negative with KOH) to positive cells (showing dilute solution positive with KOH). NaOH is less effective as a transforming agent. This might be explained on the ground that the protoplasm contains an acid (possibly a fatty acid) which makes the cell negative and which is dissolved out more rapidly by KOH than by NaOH, as happens with the fatty acids in ordinary soaps. Part of a negative cell can be changed to positive by exposure to KOH while the untreated portion remains negative. After exposure to KOH the potential the protoplasm has when in contact with NaCl may increase. At the same time there may be an increase in the potassium effect; i.e., in the change of P.D. in a positive direction observed when 0.01 M KCl is replaced by 0.01 M NaCl. In some cases the order of ionic mobilities is u _K > v _OH > u _Na. This shows that the protoplasmic surface cannot be a pore system: for in such a system all cations must have greater mobilities than all anions or vice versa.     

A THEORY OF INJURY AND RECOVERY : II. EXPERIMENTS WITH MIXTURES.

1. The equations which serve to predict the injury of tissue in 0.52 M NaCl and in 0.278 M CaCl₂ and its subsequent recovery (when it is replaced in sea water) also enable us to predict the behavior of tissue in mixtures of these solutions, as well as its recovery in sea water after exposure to mixtures. 2. The reactions which are assumed in order to account for the behavior of the tissue proceed as if they were inhibited by a salt compound formed by the union of NaCl and CaCl₂ with some constituent of the protoplasm (certain of these reactions are accelerated by CaCl₂). 3. In this and preceding papers a quantitative theory is developed in order to explain: (a) the toxicity of NaCl and CaCl₂; (b) the antagonism between these substances; (c) the fact that recovery (in sea water) may be partial or complete, depending on the length of exposure to the toxic solution.     

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.     

THE ORIGIN OF THE POTENTIAL DIFFERENCES RESPONSIBLE FOR ANOMALOUS OSMOSIS

1. Collodion bags coated with gelatin on the inside were filled with a M/256 solution of neutral salt (e.g., NaCl, CaCl₂, CeCl₃, or Na₂SO₄) made up in various concentrations of HNO₃ (varying from N/50,000 to N/100). Each collodion bag was put into an HNO₃ solution of the same concentration as that inside the bag but containing no salt. In this case water diffuses from the outside solution (containing no salt) into the inside solution (containing the salt) with a relative initial velocity which can be expressed by the following rules: (a) Water diffuses into the salt solution as if the particles of water were negatively charged and as if they were attracted by the cation and repelled by the anion of the salt with a force increasing with the valency of the ion. (b) The initial rate of the diffusion of water is a minimum at the hydrogen ion concentration of about N/50,000 HCl (pH 4.7, which is the point at which gelatin is not ionized), rises with increasing hydrogen ion concentration until it reaches a maximum and then diminishes again with a further rise in the initial hydrogen ion concentration. 2. The potential differences between the salt solution and the outside solution (originally free from salt) were measured after the diffusion had been going on for 1 hour; and when these values were plotted as ordinates over the original pH as abscissae, the curves obtained were found to be similar to the osmotic rate curves. This confirms the view expressed by Girard) Bernstein, Bartell, and Freundlich that these cases of anomalous osmosis are in reality cases of electrical endosmose where the driving force is a P.D. between the opposite sides of the membrane. 3. The question arose as to the origin of these P. D. and it was found that the P.D. has apparently a double origin. Certain features of the P.D. curve, such as the rise and fall with varying pH, seem to be the consequence of a Donnan equilibrium which leads to some of the free HNO₃ being forced from the solution containing salt into the outside solution containing no (or less) salt. This difference of the concentration of HNO₃, on the opposite sides of the membrane leads to a P.D. which in conformity with Nernst''s theory of concentration cells should be equal to 58 x (pH inside minus pH outside) millivolts at 18°C. The curves of the values of (pH inside minus pH outside) when plotted as ordinates over the original pH as abscissae lead to curves resembling those for the P. D. in regard to location of minimum and maximum. 4. A second source of the P.D. seems to be diffusion potentials, which exist even if no membranes are present and which seem to be responsible for the fact that the rate of diffusion of negatively charged water into the salt solution increases with the valency of the cation and diminishes with the valency of the anion of the salt. 5. The experiments suggest the possibility that the establishment of a Donnan equilibrium between membrane and solution is one of the factors determining the Helmholtzian electrical double layer, at least in the conditions of our experiments.     

EFFECTS OF CYANIDE ON THE PROTOPLASM OF AMEBA

The experiments seem to indicate that the toxicity of HCN and KCN for amebæ is due to their effect on the cell membrane and not on the internal protoplasm. Concentrated solutions (N/10–N/300) of HCN or KCN produce an initial increase in viscosity of the protoplasm of amebæ (immersed) which is followed by liquefaction and disintegration of the cell. Dilute solutions of HCN or KCN decrease the viscosity of the protoplasm of amebæ. Injections of HCN or KCN into amebæ produce a reversible decrease in viscosity of the protoplasm.     

THE RELATIONS OF TEMPERATURE TO THE POTASSIUM EFFECT AND THE BIOELECTRIC POTENTIAL OF VALONIA

The effect of temperature upon the bioelectric potential across the protoplasm of impaled Valonia cells is described. Over the ordinary tolerated range, the P.D. is lowest around 25°C., rising both toward 15° and 35°. The time curves are characteristic also. The magnitude of the temperature effect can be controlled by changing the KCl content of the sea water (normally 0.012 M): the magnitude is greatly reduced at 0.006 M KCl, enhanced at 0.024 M, and greatly exaggerated at 0.1 M KCl. Conversely, temperature controls the magnitude of the potassium effect, which is smallest at 25°, with a cusped time course. It is increased, with a smoothly rising course, at 15°, and considerably enhanced, with only a small cusp, at 35°. A temporary "alteration" of the protoplasmic surface by the potassium is suggested to account for the time courses. This alteration does not occur at 15°; the protoplasm recovers only slowly and incompletely at 25°, but rapidly at 35°, in such fashion as to make the P.D. more negative than at 15°. This would account for the temperature effects observed in ordinary sea water.     

THE CONCENTRATION EFFECT WITH VALONIA: POTENTIAL DIFFERENCES WITH DILUTED POTASSIUM-RICH SEA WATERS

The concentration effect with sea waters containing more than the normal amount of potassium has been studied in Valonia macrophysa. This was done by comparing the initial changes in P.D. across the protoplasm when natural sea water bathing the cell was replaced by various isotonic dilutions of KCl-rich sea waters. With small dilutions of KCl-rich sea waters, the P.D.-time curves are of the same form as with the undiluted solution, exhibiting the fluctuations characteristic of KCl-rich solutions. This indicates that with these solutions K⁺ enters Valonia protoplasm and plays an important part in the P.D. The value of the initial rise in P.D. decreases with increasing dilution. With high dilutions of KCl-rich sea waters, the P.D.-time curves are of quite different shape, resembling the curves with diluted natural sea water; the P.D. is practically independent of small changes in the concentration of potassium, and increases with increasing dilution. That is, with these higher dilutions, the sign of the concentration effect is reversed, becoming the same as with diluted natural sea water. The greater the concentration of KCl in the undiluted sea water, the higher is the critical dilution at which K⁺ ceases to influence the P.D. For a wide range of sea waters containing both KCl and NaCl, it is shown that the concentration effect above the critical dilution is determined solely by the activity of NaCl in the external solution. It is concluded that with dilute natural sea water and with high dilutions of KCl-rich sea waters we have to do with a diffusion potential, involving only the Na⁺ and Cl^- ions, which are diffusing out from the vacuole. A quantitative relation between the composition of the sea water and the critical dilution has been deduced from the classical theory of the diffusion of electrolytes. It is shown that with dilutions less than this critical value the diffusion of K⁺ in the outer non-aqueous layer of the protoplasm is directed inward; hence K⁺ enters the protoplasm from these solutions. With dilutions greater than the critical value, the diffusion of K⁺ in this layer is directed outward; hence K⁺ does not enter the protoplasm. Since the P.D. shows no evidence of this outward diffusion of K⁺, it is concluded that the amount of K⁺ ordinarily present in the protoplasm is too small to produce any lasting electrical effect, and that the outward diffusion of K⁺ from the vacuole is prevented by the mechanism responsible for the accumulation of KCl in the cell sap.     

THE SULFONIUM SALT OF MUSTARD GAS: BIS-β-[BIS(β-HYDROXYETHYL) SULFONIUM] ETHYLSULFIDE DICHLORIDE (H·2TDG)

1. The sulfonium salt H·2TDG is formed when H is mixed with even dilute solutions of TDG. Crystalline H·2TDG was isolated from such a reaction mixture. A simple method of preparation of this salt is outlined. 2. A material which differs from H·2TDG in that it hydrolyzes faster, is formed when H hydrolyzes in water. This material is probably H·1TDG but it was not isolated. Approximately 5 to 8 per cent of the original H is converted to this sulfonium salt. 3. The hydrolysis constant of M/100 H·2TDG has been determined at 20°, 25.5°, 37°, 75°, and 100°C., a temperature coefficient, Q ₁₀, of 3–4 was obtained. The effect of temperature is in agreement with that predicted by the Arrhenius equation. An activation energy of 26,000 calories was calculated.     

ELECTRICAL CHARGES OF COLLOIDAL PARTICLES AND ANOMALOUS OSMOSIS

1. It has been shown in previous publications that when solutions of different concentrations of salts are separated by collodion-gelatin membranes from water, electrical forces participate in addition to osmotic forces in the transport of water from the side of the water to that of the solution. When the hydrogen ion concentration of the salt solution and of the water on the other side of the membrane is the same and if both are on the acid side of the isoelectric point of gelatin (e.g. pH 3.0), the electrical transport of water increases with the valency of the cation and inversely with the valency of the anion of the salt in solution. Moreover, the electrical transport of water increases at first with increasing concentration of the solution until a maximum is reached at a concentration of about M/32, when upon further increase of the concentration of the salt solution the transport diminishes until a concentration of about M/4 is reached, when a second rise begins, which is exclusively or preeminently the expression of osmotic forces and therefore needs no further discussion. 2. It is shown that the increase in the height of the transport curves with increase in the valency of the cation and inversely with the increase in the valency of the anion is due to the influence of the salt on the P.D. (E) across the membrane, the positive charge of the solution increasing in the same way with the valency of the ions mentioned. This effect on the P.D. increases with increasing concentration of the solution and is partly, if not essentially, the result of diffusion potentials. 3. The drop in the transport curves is, however, due to the influence of the salts on the P.D. (ε) between the liquid inside the pores of the gelatin membrane and the gelatin walls of the pores. According to the Donnan equilibrium the liquid inside the pores must be negatively charged at pH 3.0 and this charge is diminished the higher the concentration of the salt. Since the electrical transport is in proportion to the product of E x ε and since the augmenting action of the salt on E begins at lower concentrations than the depressing action on ε, it follows that the electrical transport of water must at first rise with increasing concentration of the salt and then drop. 4. If the Donnan equilibrium is the sole cause for the P.D. (ε) between solid gelatin and watery solution the transport of water through collodion-gelatin membranes from water to salt solution should be determined purely by osmotic forces when water, gelatin, and salt solution have the hydrogen ion concentration of the isoelectric point of gelatin (pH = 4.7). It is shown that this is practically the case when solutions of LiCl, NaCl, KCl, MgCl₂, CaCl₂, BaCl₂, Na₂SO₄, MgSO₄ are separated by collodion-gelatin membranes from water; that, however, when the salt has a trivalent (or tetravalent?) cation or a tetravalent anion a P.D. between solid isoelectric gelatin and water is produced in which the wall assumes the sign of charge of the polyvalent ion. 5. It is suggested that the salts with trivalent cation, e.g. Ce(NO₃)₃, form loose compounds with isoelectric gelatin which dissociate electrolytically into positively charged complex gelatin-Ce ions and negatively charged NO₃ ions, and that the salts of Na₄Fe(CN)₆ form loose compounds with isoelectric gelatin which dissociate electrolytically into negatively charged complex gelatin-Fe(CN)₆ ions and positively charged Na ions. The Donnan equilibrium resulting from this ionization would in that case be the cause of the charge of the membrane.     

THE ACTIVATION OF STARFISH EGGS BY ACIDS

1. Exposure of unfertilized starfish eggs to dilute solutions of weak acids (fatty acids, benzoic and carbonic acids) in isotonic balanced salt solution causes complete activation with the proper durations of exposure. For each acid the rate of activation (reciprocal of optimum duration) varies with concentration and temperature; at a given temperature and within a considerable range of concentrations (e.g. 0.00075 to 0.004 M for butyric acid), this rate is approximately proportional to concentration. We may thus speak of a molecular rate of action characteristic of each acid. 2. In general the molecular rate of action increases with the dissociation constant and surface activity of the acids. In the fatty acid series (up to caproic), formic acid has the most rapid effect, acting about four times as rapidly as acetic; for the other acids the order is: acetic = propionic ≦ butyric < valeric < caproic. Carbonic acid acts qualitatively like the fatty acids, but its molecular rate of action is only about one-fourteenth that of acetic acid. 3. Hydrochloric and lactic acids are relatively ineffective as activating agents, apparently because of difficulty of penetration. Lactic acid is decidedly the more effective. The action of both acids is only slightly modified by dissolving in pure (isotonic NaCl and CaCl₂) instead of in balanced salt solution. 4. The rate of action of acetic acid, in concentrations of 0.002 M to 0.004 M is increased (by 10 to 20 per cent) by adding Na-acetate (0.002 to 0.016) to the solution. The degree of acceleration is closely proportional to the estimated increase in undissociated acetic acid molecules. Activation thus appears to be an effect of the undissociated acid molecules in the external solution and not of the ions. Acetate anions and H ions acting by themselves, in concentrations much higher than those of the solutions used, have no activating effect. The indications are that the undissociated molecules penetrate rapidly, the ions slowly. Having penetrated, the molecules dissociate inside the egg, yielding the ions of the acid. 5. When the rate of activation is slow, as in 0.001 M acetic acid, the addition of Na-acetate (0,008 M to 0.016 M) has a retarding effect, referable apparently to the gradual penetration of acetate ions to the site of the activation reaction with consequent depression of dissociation. 6. An estimate of the C_H of those solutions (of the different activating acids) which activate the egg at the same rate indicates that their H ion concentrations are approximately equal. On the assumptions that only the undissociated molecules penetrate readily, and that the conditions of dissociation are similar inside and outside the egg, this result indicates (especially when the differences in adsorption of the acids are considered) that the rate of activation is determined by the C_H at the site of the activation reaction within the egg.     

BIOELECTRIC POTENTIALS IN VALONIA : THE EFFECT OF SUBSTITUTING KCl FOR NaCl IN ARTIFICIAL SEA WATER

The P.D. across the protoplasm of Valonia macrophysa has been studied while the cells were exposed to artificial solutions resembling sea water in which the concentration of KCl was varied from 0 to 0.500 mol per liter. The P.D. across the protoplasm is decreased by lowering and increased by raising the concentration of KCl in the external solution. Changes in P.D. with time when the cell is treated with KCl-rich sea water resemble those observed with cells exposed to Valonia sap. Varying the reaction of natural sea water from pH 5 to pH 10 has no appreciable effect on the P.D. across Valonia protoplasm. Similarly, varying the pH of KCl-rich sea water within these limits does not alter the height of the first maximum in the P.D.-time curve. The subsequent behavior of the P.D., however, is considerably affected by the pH of the KCl-rich sea water. These changes in the shape of the P.D.-time curve have been interpreted as indicating that potassium enters Valonia protoplasm more rapidly from alkaline than from acidified KCl-rich sea water. This conclusion is discussed in relation to certain theories which have been proposed to explain the accumulation of KCl in Valonia sap. The initial rise in P.D. when a Valonia cell is transferred from natural sea water to KCl-rich sea water has been correlated with the concentrations of KCl in the sea waters. It is assumed that the observed P.D. change represents a diffusion potential in the external surface layer of the protoplasm, where the relative mobilities of ions may be supposed to differ greatly from their values in water. Starting with either Planck''s or Henderson''s formula, an equation has been derived which expresses satisfactorily the observed relationship between P.D. change and concentration of KCl. The constants of this equation are interpreted as the relative mobilities of K⁺, Na⁺, and Cl^- in the outer surface layer of the protoplasm. The apparent relative mobility of K⁺ has been calculated by inserting in this equation the values for the relative mobilities of Na⁺ (0.20) and Cl^- (1.00) determined from earlier measurements of concentration effect with natural sea water. The average value for the relative mobility of K⁺ is found to be about 20. The relative mobility may vary considerably among different individual cells, and sometimes also in the same individual under different conditions. Calculation of the observed P.D. changes as phase-boundary potentials proved unsatisfactory.     

CATAPHORETIC CHARGES OF COLLODION PARTICLES AND ANOMALOUS OSMOSIS THROUGH COLLODION MEMBRANES FREE FROM PROTEIN

1. It had been shown in previous papers that when a salt solution is separated from pure water by a collodion membrane, water diffuses through the membrane as if it were positively charged and as if it were attracted by the anion of the salt in solution and repelled by the cation with a force increasing with the valency. In this paper, measurements of the P.D. across the membrane (E) are given, showing that when an electrical effect is added to the purely osmotic effect of the salt solution in the transport of water from the side of pure water to the solution, the latter possesses a considerable negative charge which increases with increasing valency of the anion of the salt and diminishes with increasing valency of the cation. It is also shown that a similar valency effect exists in the diffusion potentials between salt solutions and pure water without the interposition of a membrane. 2. This makes it probable that the driving force for the electrical transport of water from the side of pure water into solution is primarily a diffusion potential. 3. It is shown that the hydrogen ion concentration of the solution affects the transport curves and the diffusion potentials in a similar way. 4. It is shown, however, that the diffusion potential without interposition of the membrane differs in a definite sense from the P.D. across the membrane and that therefore the P.D. across the membrane (E) is a modified diffusion potential. 5. Measurements of the P.D. between collodion particles and aqueous solutions (ε) were made by the method of cataphoresis, which prove that water in contact with collodion particles free from protein practically always assumes a positive charge (except in the presence of salts with trivalent and probably tetravalent cations of a sufficiently high concentration). 6. It is shown that an electrical transport of water from the side of water into the solution is always superposed upon the osmotic transport when the sign of charge of the solution in the potential across the membrane (E) is opposite to that of the water in the P.D. between collodion particle and water (ε); supporting the theoretical deductions made by Bartell. 7. It is shown that the product of the P.D. across the membrane (E) into the cataphoretic P.D. between collodion particles and aqueous solution (ε) accounts in general semiquantitatively for that part of the transport of water into the solution which is due to the electrical forces responsible for anomalous osmosis.     

On the complementary relationship between marginal nitrogen and water-use efficiencies among Pinus taeda leaves grown under ambient and CO2-enriched environments

Background and Aims

Water and nitrogen (N) are two limiting resources for biomass production of terrestrial vegetation. Water losses in transpiration (E) can be decreased by reducing leaf stomatal conductance (g_s) at the expense of lowering CO₂ uptake (A), resulting in increased water-use efficiency. However, with more N available, higher allocation of N to photosynthetic proteins improves A so that N-use efficiency is reduced when g_s declines. Hence, a trade-off is expected between these two resource-use efficiencies. In this study it is hypothesized that when foliar concentration (N) varies on time scales much longer than g_s, an explicit complementary relationship between the marginal water- and N-use efficiency emerges. Furthermore, a shift in this relationship is anticipated with increasing atmospheric CO₂ concentration (c_a).

Methods

Optimization theory is employed to quantify interactions between resource-use efficiencies under elevated c_a and soil N amendments. The analyses are based on marginal water- and N-use efficiencies, λ = (∂A/∂g_s)/(∂E/∂g_s) and η = ∂A/∂N, respectively. The relationship between the two efficiencies and related variation in intercellular CO₂ concentration (c_i) were examined using A/c_i curves and foliar N measured on Pinus taeda needles collected at various canopy locations at the Duke Forest Free Air CO₂ Enrichment experiment (North Carolina, USA).

Key Results

Optimality theory allowed the definition of a novel, explicit relationship between two intrinsic leaf-scale properties where η is complementary to the square-root of λ. The data support the model predictions that elevated c_a increased η and λ, and at given c_a and needle age-class, the two quantities varied among needles in an approximately complementary manner.

Conclusions

The derived analytical expressions can be employed in scaling-up carbon, water and N fluxes from leaf to ecosystem, but also to derive transpiration estimates from those of η, and assist in predicting how increasing c_a influences ecosystem water use.     

THE VARIATION OF ELECTRICAL RESISTANCE WITH APPLIED POTENTIAL : III. IMPALED VALONIA VENTRICOSA

Electrical resistance and polarization were measured during the passage of direct current across a single layer of protoplasm in the cells of Valonia ventricosa impaled upon capillaries. These were correlated with five stages of the P.D. existing naturally across the protoplasm, as follows: 1. A stage of shock after impalement, when the P.D. drops from 5 mv. to zero and then slowly recovers. There is very little effective resistance in the protoplasm, and polarization is slight. 2. The stage of recovery and normal P.D., with values from 8 to 25 mv. (inside positive). The average is 15 mv. At first there is little or no polarization when small potentials are applied in either direction across the protoplasm, nor when very large currents pass outward (from sap to sea water). But when the positive current passes inward there is a sudden response at a critical applied potential ranging from 0.5 to 2.0 volts. The resistance then apparently rises as much as 10,000 ohms in some cases, and the rise occurs more quickly in succeeding applications after the first. When the potential is removed there is a back E.M.F. displayed. Later there is also an effect of such inward currents which persists into the first succeeding outward flow, causing a brief polarization at the first application of the reverse potential. Still later this polarization occurs at every exposure, and at increasingly lower values of applied potentials. Finally there is a "constant" state reached in which the polarization occurs with currents of either direction, and the apparent resistance is nearly uniform over a considerable range of applied potential. 3. A state of increased P.D.; to 100 mv. (inside positive) in artificial sap; and to 35 or 40 mv. in dilute sea water or 0.6 M MgSO₄. The polarization response and apparent resistance are at first about as in sea water, but later decrease. 4. A reversed P.D., to 50 mv. (outside positive) produced by a variety of causes, especially by dilute sea water, and also by large flows of current in either direction. This stage is temporary and the cells promptly recover from it. While it persists the polarization appears to be much greater to outward currents than to inward. This can largely be ascribed to the reduction of the reversed P.D. 5. Disappearance of P.D. caused by death, and various toxic agents. The resistance and polarization of the protoplasm are negligible. The back E.M.F. of polarization is shown to account largely for the apparent resistance of the protoplasm. Its calculation from the observed resistance rises gives values up to 150 mv. in the early stages of recovery, and later values of 50 to 75 mv. in the "constant" state. These are compared with the back E.M.F. similarly calculated from the apparent resistance of intact cells. The electrical capacitance of the protoplasm is shown by the time curves to be of the order of 1 microfarad per cm.² of surface.     

BIOELECTRIC POTENTIALS IN VALONIA : II. EFFECTS OF ARTIFICIAL SEA WATERS CONTAINING LiCl,CsCl, RbCl,OR NH4Cl

In their influence on the P.D. across the protoplasm of Valonia macrophysa, Kütz., Li⁺ and Cs⁺ resemble Na⁺, while Rb⁺ and NH₄ ⁺ resemble K⁺. The apparent mobilities of the ions in the external surface layer of Valonia protoplasm increase in the order: Cs⁺, Na⁺, Li⁺ < Cl^- < Rb⁺ < K⁺ < NH₄ ⁺.     

CHANGES OF APPARENT IONIC MOBILITIES IN PROTOPLASM : I. EFFECTS OF GUAIACOL ON VALONIA

In normal cells of Valonia the order of the apparent mobilities of the ions in the non-aqueous protoplasmic surface is K > Cl > Na. After treatment with 0.01 M guaiacol (which does not injure the cell) the order becomes Na > Cl > K. As it does not seem probable that such a reversal could occur with simple ions we may assume provisionally that in the protoplasmic surface we have to do with charged complexes of the type (KX _I)⁺, (KX _II)⁺, where X _I and X _II are elements or radicals, or with chemical compounds formed in the protoplasm. When 0.01 M guaiacol is added to sea water or to 0.6 M NaCl (both at pH 6.4, where the concentration of the guaiacol ion is negligible) the P.D. of the cell changes (after a short latent period) from about 10 mv. negative to about 28 mv. positive and then slowly returns approximately to its original value (Fig. 1, p. 14). This appears to depend chiefly on changes in the apparent mobilities of organic ions in the protoplasm. The protoplasmic surface is capable of so much change that it does not seem probable that it is a monomolecular layer. It does not behave like a collodion nor a protein film since the apparent mobility of Na⁺ can increase while that of K⁺ is decreasing under the influence of guaiacol.     

THE ACTIVATION OF STARFISH EGGS BY ACIDS : II. THE ACTION OF SUBSTITUTED BENZOIC ACIDS AND OF BENZOIC AND SALICYLIC ACIDS AS INFLUENCED BY THEIR SALTS.

1. Comparison of the rates of activation of unfertilized starfish eggs in pure solutions of a variety of parthenogenetically effective organic acids (fatty acids, carbonic acid, benzoic and salicylic acids, chloro- and nitrobenzoic acids) shows that solutions which activate the eggs at the same rate, although widely different in molecular concentration, tend to be closely similar in C_H. The dissociation constants of these acids range from 3.2 x 10^–7 to 1.32 x 10^–3. 2. In the case of each of the fourteen acids showing parthenogenetic action the rate of activation (within the favorable range of concentration) proved nearly proportional to the concentration of acid. The estimated C_H of solutions exhibiting an optimum action with exposures of 10 minutes (at 20°) lay typically between 1.1 x 10^–4 M and 2.1 x 10^–4 M (pH = 3.7–3.96), and in most cases between 1.6 x 10^–4 M and 2.1 x 10^–4 M (pH = 3.7–3.8). Formic acid (C_H = 4.2 x 10^–4 M) and o-chlorobenzoic acid (C_H = 3.5 x 10^–4 M) are exceptions; o-nitrobenzoic acid is ineffective, apparently because of slow penetration. 3. Activation is not dependent on the penetration of H ions into the egg from without, as is shown by the effects following the addition of its Na salt to the solution of the activating acid (acetic, benzoic, salicylic). The rate of activation is increased by such addition, to a degree indicating that the parthenogenetically effective component of the external solution is the undissociated free acid. Apparently the undissociated molecules alone penetrate the egg freely. It is assumed that, having penetrated, they dissociate in the interior of the egg, furnishing there the H ions which effect activation. 4. Attention is drawn to certain parallels between the physiological conditions controlling activation in the starfish egg and in the vertebrate respiratory center.     

Crystallographic structure of the turbine C-ring from spinach chloroplast F-ATP synthase

In eukaryotic and prokaryotic cells, F-ATP synthases provide energy through the synthesis of ATP. The chloroplast F-ATP synthase (CF₁F_O-ATP synthase) of plants is integrated into the thylakoid membrane via its F_O-domain subunits a, b, b’ and c. Subunit c with a stoichiometry of 14 and subunit a form the gate for H⁺-pumping, enabling the coupling of electrochemical energy with ATP synthesis in the F₁ sector.Here we report the crystallization and structure determination of the c14-ring of subunit c of the CF₁F_O-ATP synthase from spinach chloroplasts. The crystals belonged to space group C2, with unit-cell parameters a=144.420, b=99.295, c=123.51 Å, and β=104.34° and diffracted to 4.5 Å resolution. Each c-ring contains 14 monomers in the asymmetric unit. The length of the c-ring is 60.32 Å, with an outer ring diameter 52.30 Å and an inner ring width of 40 Å.     

LUMIMESCENCE IN PELAGIA NOCTILUCA

1. Ca and K condition the irritability of Pelagia both in regard to rhythmical contractions and general luminescence. If either ion is omitted from the solution conduction of stimuli for pulsations and luminescence does not occur, although local responses still persist. 2. When Mg is omitted from the solution, Pelagia shows hyper-irritability with respect to rhythmical contraction and general luminescence. This is referable to the unantagonized action of K and Ca ions. 3. Exposure to the carbon arc suppresses general luminescence, the effect depending upon the quantity of light i.e. intensity x time of exposure. 4. The luminescent material secreted by Pelagia is inactive in sea water, but when put into salt solutions is activated by some of them. The efficiency of the salts, measured by brightness of light, is in the following order: MgSO₄, K₂SO₄, Na₃ citrate, KCl, BaCl₂, SrCl₂, CaCl₂, and LiCl while NaCl and MgCl₂ act as inhibitors. 5. Acidity inhibits the reaction, alkalinity promotes it. NH₄OH in concentrations 0.27 N to 0.9 N causes luminescence for 10 minutes at 20°. 6. The average temperature coefficient for the reaction of the luminescent substance when activated by ammonia or MgSO₄ is 2.18 for a temperature interval of 10°C. 7. The luminescence reaction cannot be the result of cytolysis, because (a) raising the temperature of sea water in which luminous material is immersed does not cause luminescence, although sufficient to produce cytolysis. (b) The salt solutions used in our experiments to cause luminescence, do not act cytolytically on cells in general.