bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of an S4-S5 linker in sodium channel inactivation probed by mutagenesis and a peptide blocker.
Authors: Tang L , Kallen R G , Horn R
Published: May 2004

A pair of conserved methionine residues, located on the cytoplasmic linker between segments S4 and S5 in the fourth domain of human heart Na channels (hH1), plays a role in the kinetics and voltage dependence of inactivation. Substitution of these residues by either glutamine (M1651M1652/QQ) or alanine (MM/AA) increases the inactivation time constant (tau) at depolarized voltages, shifts steady-state inactivation (h infinity) in a depolarized direction, and decreases the time constant for recovery from inactivation. The data indicate that the mutations affect the rate constants for both binding and unbinding of a hypothetical inactivation particle from its binding site. Cytoplasmic application of the pentapeptide KIFMK in Na channels mutated to remove inactivation produces current decays resembling inactivation (Eaholtz, G., T. Scheuer, and W.A. Catterall. 1994. Neuron. 12: 1041-1048.). KIFMK produces a concentration-dependent, voltage-independent increase in the decay rate of MM/QQ and MM/AA currents at positive membrane potentials (Ki approximately 30 microM), while producing only a small increase in the decay rate of wild-type currents at a concentration of 200 microM. Although MM/QQ inactivates approximately 2.5-fold faster than MM/AA in the absence of peptide, the estimated rate constants for peptide block and unblock do not differ in these mutants. External Na+ ions antagonize the block by cytoplasmic KIFMK of MM/AA channels, but not the inactivation kinetics of this mutant in the absence of peptide. The effect of external [Na+] is interpreted as a voltage-dependent knock-off mechanism. The data provide evidence that KIFMK can only block channels when they are open and that peptide block does not mimic the inactivation process.
Are altered pHi and membrane potential in hu MDR 1 transfectants sufficient to cause MDR protein-mediated multidrug resistance?
Authors: Hoffman M M , Wei L Y , Roepe P D
Published: May 2004

Multidrug resistance (MDR) mediated by overexpression of the MDR protein (P-glycoprotein) has been associated with intracellular alkalinization, membrane depolarization, and other cellular alterations. However, virtually all MDR cell lines studied in detail have been created via protocols that involve growth on chemotherapeutic drugs, which can alter cells in many ways. Thus it is not clear which phenotypic alterations are explicitly due to MDR protein overexpression alone. To more precisely define the MDR phenotype mediated by hu MDR 1 protein, we co-transfected hu MDR 1 cDNA and a neomycin resistance marker into LR73 Chinese hamster ovary fibroblasts and selected stable G418 (geneticin) resistant transfectants. Several clones expressing different levels of hu MDR 1 protein were isolated. Unlike previous work with hu MDR 1 transfectants, the clones were not further selected with, or maintained on, chemotherapeutic drugs. These clones were analyzed for chemotherapeutic drug resistance, intracellular pH (pHi), membrane electrical potential (Vm), and stability of MDR 1 protein overexpression. LR73/hu MDR 1 clones exhibit elevated pHi and are depolarized, consistent with previous work with LR73/mu MDR 1 transfectants (Luz, J.G. L.Y. Wei, S. Basu, and P.D. Roepe. 1994. Biochemistry. 33:7239-7249). The extent of these perturbations is related to the level of hu MDR 1 protein that is expressed. Cytotoxicity experiments with untransfected LR73 cells with elevated pHi due to manipulating percent CO2 show that the pHi perturbations in the MDR 1 clones can account for much of the measured drug resistance. Membrane depolarization in the absence of MDR protein expression is also found to confer mild drug resistance, and we find that the pHi and Vm changes can conceivably account for the altered drug accumulation measured for representative clones. These data indicate that the MDR phenotype unequivocally mediated by MDR 1 protein overexpression alone can be fully explained by the perturbations in Vm and pHi that accompany this overexpression. In addition, MDR mediated by MDR protein overexpression alone differs significantly from that observed for MDR cell lines expressing similar levels of MDR protein but also exposed to chemotherapeutic drugs.
Ca2+ influx activated by low pH in Chlamydomonas.
Authors: Quarmby L M
Published: May 2004

Cytosolic acidification stimulates an influx of Ca2+ which results in shedding of the two flagella of Chlamydomonas. Ca2+ influxes are also involved in the photoresponses of this alga, but it is not understood how the acidification-activated Ca2+ influx is distinguished from the Ca2+ influxes which mediate phototaxis and the photophobic response. The present study focuses on the deflagellation-inducing Ca2+ influx pathway. Influx occurs through an ion channel or transporter with low abundance or low permeability to Ca2+ (approximately 500 fmol/s/10(6) cells in 50 microM Ca2+). Ca2+ influx was potently blocked by Cd3+ (EC50 approximately 5 microM), but was insensitive to Cd2+ (Quarmby, L.M., and H.C. Hartzell. 1994. J. Cell Biol. 124:807) and organic blockers of Ca2+ channels including SKF-96365 (up to 100 microM) and flufenamic acid (up to 1 mM). Experiments with a flagella-less mutant (bald-2), isolated flagella, and a blocker of flagellar assembly (colchicine) indicated that the acidification-stimulated Ca2+ influx pathway is not localized to the flagellar membrane. The acid-stimulated influx pathway was transiently inactivated after cells shed their flagella. Inactivation did not occur in the deflagellation mutant, fa-1, although acidification-stimulated Ca2+ influx was normal. This suggests that inactivation of this pathway in wild-type cells is probably not a direct consequence of acidification nor of Ca2+ influx, but may be related to deflagellation. Recovery of deflagellation-inducing Ca2+ influx occurred within 30 min after a 30 s exposure to acid and did not require flagellar assembly. The regulation, drug sensitivity, and subcellular localization identify acidification-stimulated Ca2+ influx as a specific Ca2+ entry pathway distinct from established Ca2+ channels.
Na+ activation of the muscarinic K+ channel by a G-protein-independent mechanism.
Authors: Sui J L , Chan K W , Logothetis D E
Published: May 2004

Muscarinic potassium channels (KACh) are composed of two subunits, GIRK1 and GIRK4 (or CIR), and are directly gated by G proteins. We have identified a novel gating mechanism of KACh, independent of G-protein activation. This mechanism involved functional modification of KACh which required hydrolysis of physiological levels of intracellular ATP and was manifested by an increase in the channel mean open time. The ATP-modified channels could in turn be gated by intracellular Na+, starting at approximately 3 mM with an EC50 of approximately 40 mM. The Na(+)-gating of KACh was operative both in native atrial cells and in a heterologous system expressing recombinant channel subunits. Block of the Na+/K+ pump (e.g., by cardiac glycosides) caused significant activation of KACh in atrial cells, with a time course similar to that of Na+ accumulation and in a manner indistinguishable from that of Na(+)-mediated activation of the channel, suggesting that cardiac glycosides activated KACh by increasing intracellular Na+ levels. These results demonstrate for the first time a direct effect of cardiac glycosides on atrial myocytes involving ion channels which are critical in the regulation of cardiac rhythm.
T-type Ca2+ channel lowers the threshold of spike generation in the newt olfactory receptor cell.
Authors: Kawai F , Kurahashi T , Kaneko A
Published: May 2004

Mechanisms underlying action potential generation in the newt olfactory receptor cell were investigated by using the whole-cell version of the patch-clamp technique. Isolated olfactory cells had a resting membrane potential of -70 +/- 9 mV. Injection of a depolarizing current step triggered action potentials under current clamp condition. The amplitude of the action potential was reduced by lowering external Na+ concentration. After a complete removal of Na+, however, cells still showed action potentials which was abolished either by Ca2+ removal or by an application of Ca2+ channel blocker (Co2+ or Ni2+), indicating an involvement of Ca2+ current in spike generation of newt olfactory receptor cells. Under the voltage clamp condition, depolarization of the cell to -40 mV from the holding voltage of -100 mV induced a fast transient inward current, which consisted of Na+ (INa) and T-type Ca2+ (ICa.T) currents. The amplitude of ICa,T was about one fourth of that of INa. Depolarization to more positive voltages also induced L-type Ca2+ current (ICa,L). ICa,L was as small as a few pA in normal Ringer solution. The activating voltage of ICa,T was approximately 10 mV more negative than that of INa. Under current clamp, action potentials generated by a least effective depolarization was almost completely blocked by 0.1 mM Ni2+ (a specific T-type Ca2+ channel blocker) even in the presence of Na+. These results suggest that ICa,T contributes to action potential in the newt olfactory receptor cell and lowers the threshold of spike generation.
PHOTOTROPISM OF DIXIPPUS MOROSUS
Authors: Yagi N.
Published: May 2004

1. Local differences in the effects of stimulation of parts of the eye by light are expressed in Dixippus morosus by differential circus movements.

2. The angle of inclination of the body axis toward one source of light when the animal is on a vertical plane with light from one side is inversely proportional to the logarithm of the intensity of the light.
THE SURFACE TENSION OF PHYSIOLOGICAL SOLUTIONS
Authors: Johlin J. M.
Published: May 2004

1. Data are given to show that surface tension values obtained by the ring method cannot be considered reliable when absolute values are desired.

2. Data are given to show that, in the case of solutions of semicolloids, surface tension values obtained for a definite period of time following the formation of a new interface cannot always be consistently reproduced by the ring method.

3. It is shown that in the case of solutions of semicolloids, equilibrium values are not readily obtained and should generally not be assumed to have been reached after any definite period of time.

4. The general difficulty of interpreting surface tension values obtained in the case of solutions of semicolloids, by any method, is emphasized.
THE DETERMINATION OF THE EQUIVALENT WEIGHT OF PROTEINS
Authors: Stearn Allen E.
Published: May 2004

The magnitude of the correction in the fifth column of Table III may be open to some doubt, as are all corrections of such a character, and the significance of the above experiment in the author's mind lies not so much in the actual magnitude of the values given in the last column of this table as in their comparative magnitudes. For this reason the entire experiment reported was performed in a single session using the same gelatin solution, so that, whatever the magnitude of the correction, it would be the same in all cases.

Actually the results in the case of the acid titrations are in fair agreement with those of Hitchcock (8). In the present experiment it is seen that, within the limits of experimental error, one gets the same value for the number of cc. of tenth normal acid bound by 1 gm. of gelatin whether one titrates with the acid or with the gelatin. In the case of the base there is a small difference, due probably to carbon dioxide, but this effect is in a direction opposite to that which one would expect on the assumption that it is due to appreciable adsorption.

From this it is concluded that the binding due to adsorption in the case of gelatin is not significant compared to that due to chemical neutralization. The author realizes that gelatin is a poor choice for a basis of generalizations, and similar work is at present in progress on various other proteins. He does feel, however, that the conclusions of Hoffman and Gortner from their work on the prolamines may also be too widely generalized, and that, on the whole, the acid or alkali bound by adsorption in the case of proteins will not constitute the large majority of the total amounts bound, though certainly one will expect a certain amount of such binding in all cases. It also seems that before placing undue emphasis on the conclusions of these workers the possibilities of equivocal results due to specific technique should be considered. This technique consisted in introducing weighed amounts of dry protein into a definite volume of standard acid or base at the equilibrium temperature, in general, and, "after about 15 minutes, during which time the flask was shaken several times," determining the pH of the equilibrium solution. Is it possible that the actual speed of solution of the protean is such that, even though reproducible results are obtained using identical technique, actual equilibrium conditions are approached only when comparatively high concentrations of acid or alkali are employed, in which cases the solution velocity of the protein may he expected to be greater, other factors remaining constant?
THE VAPOR PRESSURE OF DOG'S BLOOD AT BODY TEMPERATURE
Authors: Grollman Arthur
Published: May 2004

The vapor pressures of dog's blood and blood plasma were determined at 37.5° by the dynamic method and the osmotic pressures calculated from the experimental data. The vapor pressures calculated from experimentally determined freezing point data agreed, within the experimental error, with the values obtained from direct measurement. The vapor pressure lowering produced by the colloid constituents of the blood was also determined and found to be minimal compared to that of the other constituents.
PHOTIC ORIENTATION BY TWO POINT-SOURCES OF LIGHT
Authors: Mitchell Wm. Hinckley , Crozier W. J.
Published: May 2004

General formulæ are derived for the orientation of phototropic organisms in a field illuminated by two point-sources of light in the same horizontal plane.

It is shown that formulæ previously found may all be derived as special cases of these general equations.
THE MECHANISM OF THE INFLAMMATORY PROCESS
Authors: Abramson Harold A.
Published: May 2004

1. Quartz particles and certain other particles move cataphoretically in certain soft gelatin gels, with the same velocity as in the sol. The speed is a function of the true viscosity of the sol or gel, and it is

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apparently not altered in these soft gels by the presence of gel structure. It is proportional to the applied difference of potential.

2. This finding is compatible with the fact that certain sols undergo gelation with no increase of the true viscosity although a marked change in the apparent viscosity takes place.

3. Red cells in soft gelatin-serum gels show a distinct difference in behavior. They migrate through the sol or gel with a speed that is about twice as great as the leucocytes and quartz particles, which latter particles migrate with the same velocity. This ratio has been found to hold for serum and plasma. The absolute velocities are comparatively slightly decreased by the presence of the gel.

4. In more concentrated or stiffer gels, leucocytes, red cells and quartz particles all move at first with the same velocity. By producing mechanical softening of these gels (shearing from cataphoretic movement of the micells within the cell) the red cells presently resume their previous property of independent migration through the gel.

5. The movements of particles in gelatin gels produced by a magnetic force or the force of gravity are of a different nature than those movements produced by cataphoresis.

6. The mechanical nature of obstruction to the cataphoretic migration of leucocytes and red cells in fibrin gels is briefly described.

7. The correlation of cataphoresis of microscopic particles in gels with the order of magnitude and nature of the potential differences in the capillary wall, lends additional evidence to the theory that polymorphonuclear leucocyte emigration and migration are dependent upon these potential differences.
HEMOLYSIS BY SAPONIN AND SODIUM TAUROCHOLATE, WITH SPECIAL REFERENCE TO THE SERIES OF RYVOSH
Authors: Yeager J. Franklin
Published: May 2004

1. The series of Ryvosh is obtained when hemolysis of the red cells of the animals concerned occurs with saponin as the lytic agent.

2. The series of Ryvosh is not obtained when R∞ is taken as the resistance constant and sodium taurocholate is used to hemolyse the cells of the same animals.

3. The hemolysin sodium taurocholate has been found to differ from saponin in that the time-dilution curves are found to approach their respective asymptotes with different values of κ.
ON THE GEOTROPIC ORIENTATION OF YOUNG MAMMALS
Authors: Crozier W. J. , Pincus G.
Published: May 2004

Constants in equations of curves describing the geotropic orientation of young rats are repeatedly obtainable from litters of successive generations of the same inbred strains. Different inbred strains have been obtained for which the respective constants are quite unlike.

Such findings show how necessary it is to employ biologically uniform material in experiments of this kind. And at the same time they are convenient as a starting point for genetic analysis.
GEOTROPIC ORIENTATION IN ARTHROPODS
Authors: Kropp Benjamin , Crozier W. J.
Published: May 2004

On an inclined surface the fiddler crab Uca pugnax, during sidewise progression, orients upward through an angle θ on the surface. The extent of negatively geotropic orientation (θ) is a rectilinear function of sin α, where α is the inclination of the surface to the horizontal. This equation differs from that describing the geotropic orientation of various other animals. The difference is traced to the fact that from an initial position with the transverse axis of the body horizontal the crab is required to turn upward to an extent such that the vertical line from its center of gravity pierces the inclined surface within the base of support provided by the legs. This leads to the equation sec θ/tan α = const., which is obeyed within the limits of precision of the measurements. This type of control of geotropic orientation represents an extension of the "muscle tension theory," and is in no sense in conflict with this view. The assumptions underlying the analytical expression connecting θ and α are verified by the asymmetry in the orientation of male fiddlers, which is shown to be due to the presence of the enlarged chela and which disappears when the claws are removed.
SPECTROPHOTOMETRIC STUDIES OF PENETRATION
Authors: Irwin Marian
Published: May 2004

Spectrophotometric measurements show that it is chiefly the trimethyl thionin that is present in the sap extracted from the vacuoles of uninjured cells of Nitella or Valonia which have been placed in methylene blue solution at a little above pH 9. Whether these measurements were made immediately or several hours later the same results were obtained. Methylene blue is detected in the sap (1) when the cells are injured or (2) when the contamination of the sap from the stained cell wall occurs at the time of extraction.

The sap is found to be incapable of demethylating methylene blue dissolved in it even on standing for several hours.

It is somewhat uncertain as to whether the trimethyl thionin penetrated as such from the external methylene blue solution which generally contains this dye as impurity (in too small concentration for detection by spectrophotometer but detectable by extraction with chloroform), or whether it has formed from methylene blue in the protoplasm. The evidences described in the text tend to favor the former explanation.

Theory is discussed on basis of more rapid penetration of trimethyl thionin (in form of free base) than of methylene blue, or of trimethyl thionin in form of salt.
HEMOLYSIS OF CHICKEN BLOOD
Authors: Shattuck G. Edgar
Published: May 2004

1. The time-dilution curves are given for the hemolytic action of saponin, sodium taurocholate, and sodium oleate on nucleated chicken erythrocytes.

2. Saponin and sodium taurocholate cause hemolysis but leave the nuclei and ghosts in suspension, thereby making the end-point of hemolysis more arbitrary than the clear end-point for non-nucleated cell hemolysis.

3. The curves of hemolysis by saponin and taurocholate are shown to be of the same nature as are found in the hemolysis of non-nucleated cells.

4. Sodium oleate causes first hemolysis and then, in the stronger solutions, causes karyolysis. Two pairs of values for κ and c = ∞ are thus obtainable for the same reaction, one pair for the destruction of corpuscular membrane, the other pair for the destruction of the nucleus.

5. Viscosity changes are found in the lysin-cell system with strong concentrations of sodium taurocholate and sodium oleate. Time-viscosity curves are given for these changes.

6. Microscopically, the action of these lysins on the nucleated chicken red cell appears to be similar to their action on the non-nucleated erythrocytes.
ELECTRIC IMPEDANCE OF SUSPENSIONS OF SPHERES
Authors: Cole Kenneth S.
Published: May 2004

A general expression has been derived for the electric impedance of a suspension of spheres each having a homogeneous non-reactive interior and a thin surface layer with both resistance and reactance. The applications and limitations of impedance measurements on such suspensions are discussed.
CHEMICAL ANTAGONISM OF IONS
Authors: Simms Henry S.
Published: May 2004

Magnesium ions decrease the activity of divalent organic anions much more than the normal decrease produced by sodium ions. The effect is very large with short chain acids, particularly oxalic acid.

The addition of sodium or potassium ions produces a marked decrease in the effect of magnesium diions on the activity of oxalate diions.

Quantitative data on 0.005 molar solutions of oxalic diion over a wide range of concentrations of MgCl2 and of NaCl (or KCl) show that the following equation is obeyed:

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where A is an empirical value dependent on the concentration of oxalate diion (0x=).

This equation has been shown to hold down to zero ionic strength of Na+ and K+, and hence to be valid in the physiological range.

These observations are of biological interest since the activity of proteins should (like oxalic acid) show a similar antagonism.
THE BRIGHTNESS OF THE LIGHT OF THE WEST INDIAN ELATERID BEETLE, PYROPHORUS
Authors: Harvey E. Newton , Stevens Kenneth P.
Published: May 2004

The maximum brightness of one of the prothoracic light organs of the West Indian elaterid beetles, Pyrophorus (measured at Princeton, New Jersey) was found to be .045 lambert, or .045 lumen per sq. cm. at 20°C. This corresponds to .0002 candle for one organ, or .0004 candle for the pair of prothoracic organs.
THE THERMIC EFFECT OF DEATH
Authors: Lepeschkin W. W.
Published: May 2004

The thermic effect of death as observed on yeast is about 2 gm. calories per gram of dry substance and is therefore very small as compared with the heat produced in most of the exotherm chemical reactions. As the chemical compounds composing living matter have a very great molecular weight, the decomposition of their molecule which brings about death produces more heat than the decomposition of the molecule of some explosive substances. This explains the great instability of the principal compounds of living matter.
DARK ADAPTATION AND THE LIGHT-GROWTH RESPONSE OF PHYCOMYCES
Authors: Castle E. S.
Published: May 2004

1. A single-celled, elongating sporangiophore of Phycomyces responds to a sufficient increase in intensity of illumination by a brief increase in growth rate. This is the "light-growth response" of Blaauw.

2. The reaction time is compound, consisting of an exposure period and a latent period (this comprising both the true latent period resulting from photochemical action and any "action time" necessary for the response). During the latter period the plant may be in darkness, responding nevertheless at the end of the latent period.

3. Both light adaptation and dark adaptation occur in the sporangiophore. The kinetics of dark adaptation can be accounted for on the basis of a bimolecular reaction, perhaps modified by autocatalysis. Attention is called to the bimolecular nature of the "dark" reaction in all other photosensory systems that have been studied, in spite of the diversity of the photosensitive substances themselves and of the different forms of the responses to light.
THE PENETRATION OF STRONG ELECTROLYTES
Authors: Cooper W. C. , Dorcas M. J. , Osterhout W. J. V.
Published: May 2004

The entrance of strong electrolytes into Valonia is very slow unless the cells are injured. This, together with the very high electrical resistance of the protoplasm, suggests that they may penetrate largely as undissociated molecules formed at the surface of the protoplasm by the collision of ions.

Under favorable circumstances KCl may be absorbed to the extent of 3 x 10–8 mols per hour per sq. cm. of surface together with about 0.17 as much NaCl. Other substances which seem to penetrate to some extent are Li, Rb, Br, BrO3, I, IO3, and selenite.

Little or no penetration is shown by SCN, ferricyanide, ferrocyanide, formate, salicylate, tungstate, seleniate, NO2, SO3, Sb, glycerophosphate, and many heavy metals and the alkaline earths.

In sea water whose specific gravity had been increased by CsCl cells of Valonia floated for over a year and there was little or no penetration of Cs except as the result of injury.

The penetration of NH4Cl decreases the specific gravity of the sap and causes the cells to float: under these circumstances they live indefinitely. It is probable that NH3 or NH4OH penetrates and is subsequently changed to NH4Cl. It would seem that if the sea contained a little more ammonia this would be a floating organism.
THE PERMEABILITY OF DRY COLLODION MEMBRANES. II
Authors: Northrop John H.
Published: May 2004

The rate of penetration and the solubility of H, O, N, NH3, H2O, HCl gas, CO2, formic, acetic, chloracetic, dichloracetic acid, glycerol, phenol and mercury bichloride in dry collodion membranes have been measured.

The rate of penetration of H and CO2 is the same whether the membrane and gas are dry or whether the membrane is immersed in water.

The solubility of CO2, acetic acid, phenol and water in collodion is completely reversible and is proportional to the concentration (or vapor pressure) in low concentrations and independent of the surface of the collodion.

The size of the pores has been calculated from the vapor pressure of water in the collodion and from the rate of flow of water through the membrane. The results do not agree and are not consistent with the observed rates of penetration.

The relative rates of penetration of the gases bear no relation to the density of the gas.

When the results are corrected for the solubility of the substances in the collodion and expressed as the diffusion coefficient in collodion they show that the diffusion coefficient increases rapidly as the molecular weight decreases.
STUDIES ON PERMEABILITY OF MEMBRANES
Authors: Green Arda A. , Weech A. A. , Michaelis L.
Published: May 2004

Two methods of measuring the electrical conductivity of the dried collodion membrane in contact with an electrolyte solution are described and the results of such measurements with different electrolytes in different ranges of concentration recorded. Some of the difficulties encountered in making these measurements are outlined. Of special interest was the fact that each membrane with each electrolyte showed a maximum level of resistance at a certain point in the dilution scale, a level which was not surpassed by further dilution. It is believed that this level was fixed by the collodion itself rather than by the contiguous electrolyte solution. Its existence limited the results available for reasonable interpretation. In relatively concentrated solutions the conductivity was shown to be approximately proportional to the concentration. With different electrolytes in the same concentration it was shown that the conductivities varied much more than in simple solutions without a membrane and that they fell in the order HCl > KCl > NaCl > LiCl.

A method was described whereby the electrolyte content of a membrane in contact with different chloride solutions could be determined. It was shown that a membrane saturated with either 0.5 N HCl or 0.5 N KCl had practically the same total electrolyte content whereas the same membrane in contact with 0.5 N LiCl contained only half the quantity. These results were used in interpreting the conductivity data, the evidence presented strongly suggesting that two factors are operative in causing the widely divergent conductivities recorded with different electrolytes. The first factor depended on the quantity of electrolyte which can enter the membrane pores, a quantity dependent on the size of the pores and the volume of the larger of the two hydrated ions of the electrolyte. This factor was the chief one in determining the difference in conductivity between KCl and LiCl. The second factor was concerned with differences in the mobility of the various cations within the membrane brought about by friction between the moving ions and the pore walls. With KCl and HCl the quantity of electrolytes entering the membrane was in each case the same, being determined by the size of the larger Cl- ion. The widely different conductivity values were explained as due to the changes in the mobility of the two cations within the membrane pores.
STUDIES ON PERMEABILITY OF MEMBRANES
Authors: Weech A. A. , Michaelis L.
Published: May 2004

A study of the behavior of the dried collodion membrane toward the bivalent calcium ion showed that:

1. There is almost no potential difference established across a membrane separating two calcium chloride solutions of 0.1 and 0.01 N concentrations.

2. The transfer numbers of chlorine and calcium, as measured in electrical transfer experiments, are both close to 0.5.

3. A sample of membrane in equilibrium with a solution of calcium chloride has an extremely high electrical resistance, greater than is observed with solutions of the chlorides of any of the monovalent cations.

4. The total electrolyte content of a membrane in equilibrium with a solution of calcium chloride was only 20 per cent of that observed when the solution was lithium chloride and 10 per cent of that found when the solution was potassium chloride.

In explaining these various results it is supposed that (1), (2) and (3) are all the result of (4), that is, of the inability of the calcium ion to penetrate any but the largest of the membrane pores. As the total quantity of electrolyte able to penetrate the membrane is very small the electrical conductivity must also be very small. Moreover, the few larger pores that are large enough to transport the hydrated calcium ion are too large to exert any appreciable effect in decreasing the mobility of the anion. Thus the membrane has no effect in modifying the potentials established across concentration chains with CaCl2 and the transfer numbers determined experimentally are what one would expect if no membrane were present.
THE INFLUENCE OF SIZE, SHAPE AND CONDUCTIVITY OF MICROSCOPICALLY VISIBLE PARTICLES ON CATAPHORETIC MOBILITY
Authors: Abramson H. A. , Michaelis L.
Published: May 2004

The electrophoretic mobility of microscopically visible particles is independent of size, shape and conductivity of the particle within the limits of the experimental error. This is valid for extreme variations in size, shape and conductivity.
THE CATAPHORETIC VELOCITY OF MAMMALIAN RED BLOOD CELLS
Authors: Abramson Harold A.
Published: May 2004

1. No significant change with time (to 24 hours) in the cataphoretic velocity of certain mammalian red cells occurs when the cells are suspended in M/15 phosphate buffer at pH = 7.35. Neither successive washings nor standing effect a change.

2. In M/15 phosphate buffer at pH 7.35 ± 0.03 the following order of red cell velocity has been obtained. The numbers in parenthesis are µ per second per volt per centimeter.

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The order, though not the absolute values, was the same in buffered isotonic dextrose. Human and rabbit cells showed similar differences when both were studied simultaneously in the serum of either. Under these conditions, there is no apparent relationship between zoological Order and cataphoretic velocity.

3. Cholesterol and quartz adsorb gelatin from dilute solution in the phosphate buffer. Red cells, on the other hand, even after 24 hours contact with gelatin solution, retain their previous velocity.

4. Pregnant and non-pregnant white female humans have the same red cell cataphoretic velocity. (The cells were not agglutinated.)

5. In a series of severe anemias no significant change in cataphoretic velocity was in general apparent, although marked changes in the morphology of the red cells were present.
THE CONCENTRATION EFFECT IN NITELLA
Authors: Osterhout W. J. V. , Harris E. S.
Published: May 2004

A method distinguishing between the concentration effect due to the cell wall and that due to the protoplasm is described: the importance of this lies in the fact that if the protoplasm shows a concentration effect one or both ions of the salt must tend to enter its outer surface.

Studies on the concentration effect of KCl with living protoplasm of Nitella show that when P.D. is plotted as ordinates and the logarithm of concentration as abscissæ the graph is not the straight line demanded in the ideal case by theory but has less slope and is somewhat concave to the axis of the abscissæ.

With a variety of salts the dilute solution is positive, which indicates that the cation has a greater mobility in the protoplasm than the anion or that the partition coefficient of the cation (Ac) increases faster than that of the anion (Aa) as the concentration increases. If the result depended on the partition coefficients we should say that when Ac ÷ Aa increases with concentration the dilute solution is positive. When Ac ÷ Aa decreases as the concentration increases the dilute solution is negative. In either case the increase in concentration may be accompanied by an increase or by a decrease in the relative amount of salt taken up. Theoretically therefore there need be no relation between the sign of the dilute solution and the relative amount of salt taken up with increasing concentration.

Hypothetical diagrams of the electrical conditions in the cell are given.

If we define the chemical effect as the P.D. observed in leading off at two points with equivalent concentrations of different salts we may say that the chemical effect of the protoplasm is very much greater than that of the cell wall.
THE EFFECT OF SUDDEN CHANGES OF TEMPERATURE ON PROTOPLASMIC STREAMING
Authors: Cook S. F.
Published: May 2004

A sudden fall of temperature of 15° to 20° causes a complete cessation of the protoplasmic streaming in Nitella. The recovery of the normal rate follows a definite course and the time of recovery is dependent on the temperature. Evidence is adduced to show that the inhibition of streaming is due to a physical phenomenon.
A PRELIMINARY STUDY OF THE REDUCING INTENSITY OF LUMINOUS BACTERIA
Authors: Harvey E. Newton
Published: May 2004

The effect of a series of redox indicators and systems has been tested with a suspension of luminous bacteria (B. fischeri) in M/4 phosphate buffer of PH = 7.6.

The indicators behave as expected from their position in the redox series, the most positive being reduced rapidly even in presence of air and before luminescence of the bacteria disappears, those of intermediate position at the time luminescence disappears, and the more negative only long after the luminescence had ceased, due to utilization of oxygen by the bacterial respiration. Indigo monosulphonate was the only indicator not reduced on long standing of a bacterial suspension. The aerobic redox potential may be placed at an RH = 18–20 and the anaerobic potential at an RH = 8–10.

Ferricyanides do not affect luminescence and behave as if they could not penetrate the bacterial cell. Quinone and the napthoquinones cause progressive dimming of luminescence in any concentration which affects the light but it cannot be definitely stated that this is due to rapid oxidation of luciferin although it seems likely in the case of quinone. Some indophenols dim the luminescence at first, followed by return of brightness, which is interpreted to mean rapid oxidation of luciferin while the indophenol is unreduced, more luciferin production after reduction of indophenol. The more negative redox systems do not affect the luminescence. Investigation of indicator reduction and luminescence is being continued.
THE PREPARATION OF COMPLETELY COAGULATED HEMOGLOBIN
Authors: Anson M. L. , Mirsky A. E.
Published: May 2004

As a preliminary to the study of the reversal of the coagulation of hemoglobin several methods are described for the preparation of completely denatured and coagulated hemoglobin and the evidence is given that hemoglobin is a typical coagulable protein.
MEASUREMENTS OF THE METABOLISM OF TWO PROTOZOANS
Authors: Emerson Robert
Published: May 2004

1. The respiration of Amoeba proteus was measured. 10 c. mm. of cells were found to use about 1.6 mm.3 of oxygen per hour at 20°C. The respiratory quotient was found to be nearly unity.

2. No anaerobic metabolism was found for Amoeba.

3. The respiration of Blepharisma was found to be from 3 to 7 mm.3 oxygen per hour for 10 mm.3 cells. The respiratory quotient was about 1.

4. Blepharisma was shown to have a definite anaerobic metabolism. 80 mm.3 cells caused the evolution of 12.5 mm.3 carbon dioxide per hour at 20°C. in the presence of bicarbonate.
ON THE BEHAVIOR OF NICKEL CARBONATE IN RELATION TO PHOTOSYNTHESIS
Authors: Emerson Robert
Published: May 2004

The writer was unable to prepare a sample of nickel carbonate which would give any indication of photosynthetic activity. If Professor Baly's preparations are really active, I believe there is some detail in his procedure which he has failed to mention.
ELECTROKINETIC PHENOMENA
Authors: Abramson Harold A.
Published: May 2004

1. The effect of human and rabbit sera on the cataphoretic mobility of glass and quartz particles, and of paraffin oil droplets, was studied in serum dilutions (with 0.85 per cent NaCl) from 1:50 to 1:1,000,000, over a pH range of 3.6 to 9.3.

2. Under the conditions described, these various types of particles adsorbed protein partially or completely from the most dilute solution giving these particles electrokinetic properties characteristic of certain proteins, probably here those of serum albumin.

3. Quartz particles and paraffin oil droplets both have an isoelectric point between 4.7 and 4.8 in a 1:50 serum dilution.

4. The biological importance of these findings is discussed.

5. A non-polarizable electrode composed of

See PDF for Structure

is described for use with cataphoresis cells.
A STUDY OF THE BACTERICIDAL ACTION OF ULTRA VIOLET LIGHT
Authors: Gates Frederick L.
Published: May 2004

1. Wide differences in the intensity of incident ultra violet energy are not accurately compensated by corresponding changes in the exposure time, so that the Bunsen-Roscoe reciprocity law does not hold, strictly, especially for bactericidal action on young, metabolically and genetically active bacteria. In the present series of experiments, however, the energies used at various wave lengths did not differ by so much as to cause a significant error in the reported reactions.

2. The longer wave length limit of a direct bactericidal action on S. aureus was found to be between 302 and 313 mµ. The shorter limit was not determined because the long exposures required vitiate quantitative results. Bactericidal action was observed at λ225 mµ.

3. The temperature coefficient of the bactericidal reaction approaches 1 and thus furnishes empirical evidence that the direct action of ultra violet light on bacteria is essentially physical or photochemical in character.

4. The hydrogen ion concentration of the environment has no appreciable effect upon the bactericidal reaction between the limits of pH 4.5 and 7.5. At pH 9 and 10 evidence of a slight but definite increase in bacterial susceptibility was noted, but this difference may have been due to a less favorable environment for subsequent recovery and multiplication of injured organisms.

5. Plane polarization of incident ultra violet radiation has no demonstrable effect upon its bactericidal action.

In a third paper of this group the ratios of incident to absorbed ultra violet energy at various wave lengths and the significance of these relations in an analysis of the bactericidal reaction will be discussed.
THE SUBSTRATE IN PEPTIC SYNTHESIS OF PROTEIN
Authors: Borsook Henry , MacFadyen Douglas A. , Wasteneys Hardolph
Published: May 2004

1. Experiments are described in which it was observed that the yield of protein that can be synthesized by pepsin from a given peptic digest is highest when the hydrolyzing action of the pepsin is stopped as soon as all the protein has disappeared from the solution; and that the longer the digest is permitted to contain active enzyme the more the yield diminishes.

2. Exposure of the digest to a hydrogen ion concentration of pH 1.6 in the absence of active enzyme, does not cause a diminution in the amount of protein which can be synthesized from that digest.

3. Synthesis can be effected also in concentrated solutions of isolated fractions of a peptic digest, i.e. of proteose and of peptone. The yields are approximately the same as in similar concentrations of the whole digest, though the proteins so synthesized differ in some respects from those obtained from the whole digest.

4. The cessation of synthesis in any one digest is due to the attainment of equilibrium and not to the complete utilization of available synthesizeable material. The amount of the equilibrium yield, on the other hand, is dependent on the amount of synthesizeable material in the digest.

5. These observations are taken to show that the synthesizeability of a given mixture of protein cleavage products by pepsin depends upon its possession of a special complex in these products. This complex appears as a result of the primary hydrolysis of the protein molecule by pepsin and is decomposed in the slow secondary hydrolysis which ensues as digestion is prolonged.
A CRYSTALLOGRAPHIC STUDY OF PURE CARBONMON-OXIDE HEMOGLOBIN
Authors: Boor Alden Kinney
Published: May 2004

1. Photomicrographs of crystals of pure carbonmonoxide hemoglobin of the following species are presented; ox, sheep, hog, dog, turkey, rat, horse, chicken and guinea pig. Photomicrographs of the oxyhemoglobin crystals of the following species are also shown: ox, sheep, hog, dog, rat, horse and guinea pig. The crystals were formed from the pure protein by adding a suitable amount of ethyl alcohol and maintaining a temperature of 0°C., or lower.

2. In some species a sufficient difference is shown between the carbonmonoxide hemoglobin and oxyhemoglobin crystals to distinguish these compounds, but the photographs of crystals of carbonmonoxide hemoglobin and oxyhemoglobin of some species, such as guinea pig, show no appreciable difference.

3. Differences between the carbonmonoxide hemoglobins, as well as between the oxyhemoglobins, of the different species studied are indicated.

4. The carbonmonoxide hemoglobin crystals from the bloods studied are species specific in their nature, and, in many cases, can be distinguished from the analogous oxyhemoglobin by crystallographic study.
THE KINETICS OF ENZYME REACTIONS: SCHÜTZ'S LAW
Authors: Moelwyn-Hughes E. A. , Pace J. , Lewis W. C. M.
Published: May 2004

1. A review of the applicability of Schütz's Law to enzymic reactions is given.

2. The theoretical deductions of the Law, (a) on the basis of the law of mass action, (b) on the basis of the adsorption theory, are given and the significance of the assumptions made in these deductions pointed out.

3. It is shown that the true critical increment for an enzymic reaction is equal to twice the critical increment calculated from the Schütz constant ks, if the heat of decomposition of the enzyme-products complex be neglected.

4. Experiments are described on the tryptic hydrolysis of casein at 30°C. and 404C. The foregoing considerations are applied to the experimental results obtained.
THE NON-LOGARITHMIC ORDER OF DEATH OF SOME BACTERIA
Authors: Rahn Otto
Published: May 2004

In a previous paper, it has been shown that the logarithmic order of death of bacteria can be accounted for by the assumption that each cell contains one or several extremely sensitive molecules and that the destruction or inactivation of any one of these prevents multiplication of the cell.

In this paper, the apparent exceptions to the logarithmic order are dealt with. It has been shown that the decreasing death rate can well be accounted for by the assumption of a variation in resistance of the cells under test.

The few cases of increasing death rates might be indicative of a different cell structure, requiring the destruction of 2 or 3 molecules before multiplication is made impossible. More probable, however, is the assumption that these bacteria behave exactly like the others, and that the apparently larger number of molecules per cell is caused by our imperfect method of counting living bacteria by the plating method where a cluster of several cells can be counted only as one cell. Bacteria with a tendency for clustering are likely to give results resembling the expectation for several reacting molecules per cell.
PHOTOTROPISM AND THE LIGHT-SENSITIVE SYSTEM OF PHYCOMYCES
Authors: Castle E. S.
Published: May 2004

1. The reaction time of the direct growth response of the sporangiophore of Phycomyces to light consists of a series of at least three major identifiable components: (a) an exposure period during which photochemical change occurs; (b) a latent period involving products directly consequent upon the photochemical action; and (c) an action-time occupying a further interval before the growth acceleration appears.

2. The reaction time of the phototropic response of the sporangiophore following stimulation by unilateral illumination is also compound, and is made up of at least three components comparable to those of the direct growth response.

3. The reaction time of each mode of response is constant for a particular intensity of illumination, provided that the duration of the exposure period exceeds a certain value. Below that value the reaction time increases progressively as the exposure time decreases.

4. The reaction time of each mode of response is found to vary similarly as a function of the duration of exposure to light. It is therefore concluded that the two responses are based on the same light-sensitive system. This conclusion accords with the conception of plant phototropism developed by Blaauw.

5. If a constant representing the action-time is subtracted from the reaction times for either mode of response, the reciprocals of the resulting numbers follow a linear sequence when plotted against the durations of the exposure to light. The rate of the process occurring during the latent period is therefore considered to be directly proportional to the amount of preceding photochemical change.