bluuebunny/crossref_metadata_2025_split huggingface dataset:
POTASSIUM-DEPENDENT SODIUM EXTRUSION BY CELLS OF PORPHYRA PERFORATA, A RED MARINE ALGA
Authors: Eppley Richard W. 
Published: May 2004

Potassium-free artificial sea water causes a loss of cell potassium and a gain of cell sodium in Porphyra perforata, which is not attributable to an inhibition of respiration.
On adding KCl or RbCl to such low potassium, high sodium tissues, net accumulation of potassium or rubidium takes place, accompanied by net extrusion of sodium. Rates of potassium or rubidium accumulation and sodium extrusion are proportional to the amount of KCl or RbCl added only at low concentrations. Saturation of rates is evident at KCl or RbCl concentrations above 20–30 mM, suggesting the role of an ion carrier mechanism of transport.
Evidence for and against mutually dependent sodium extrusion and potassium or rubidium accumulation is discussed.
SOME OBSERVATIONS ON CARDIAC AUTOMATISM IN CERTAIN ANIMALS
Authors: Jensen David 
Published: May 2004

Certain aspects of the acetylcholine hypothesis of cardiac automaticity have been tested in vitro with spontaneously beating cardiac tissue from rabbits, rats, dams, and hagfish. The beat of atria from rabbits and rats may be depressed or excited by acetylcholine, depending upon the state of the tissue. Proguanil and cocaine inhibition of the beat in the rat may be antagonized by acetylcholine so that reversal of the depression occurs. The action of acetylcholine on the hearts of clams was found to be strictly inhibitory. Proguanil and cocaine, in contrast to their action on mammalian atria, exert a stimulatory effect on the heart of the molluscs studied. In fact, cocaine stimulated these hearts when they were inhibited by acetylcholine.
Studies on the non-innervated hagfish heart revealed that this tissue is completely insensitive to the action of acetylcholine. Extracts prepared from beating hearts of this species will accelerate hypodynamic hearts of the hagfish as well as of the mussel. An extract of the neurogenic lobster heart was without effect on the hagfish heart. Proguanil was likewise ineffective in concentrations which produced inhibition and excitation in rat and clam hearts respectively.
It was concluded that acetylcholine does not play a role in the myogenic automatism of all species, and that another mechanism is responsible is suggested on the basis of results obtained in the hagfish hearts.
THE RELEASE AND STABILITY OF THE LARGE SUBUNIT OF DNA FROM T2 AND T4 BACTERIOPHAGE
Authors: Thomas Charles A. 
Published: May 2004

T2 and T4 bacteriophage have been exposed to various treatments which are known to release the encapsulated DNA. The unseparated reaction products have been examined by autoradiography. The results indicate the presence of one large subunit of DNA (molecular weight 45 x 106) for each former phage particle. Some smaller subunits of molecular weight 12 x 106 have been observed.
The large subunit is sensitive to very small amounts of DNAase, and is resistant to mixed proteases and cannot be dispersed by banding in cesium chloride density gradients.
The sensitivity to fragmentation by P32 decay and the increase in this sensitivity following heat treatment are best explained by assuming that the large subunit is a duplex of polynucleotide strands over most of its length.
The presence of hypothetical non-DNA interconnections is considered.
EFFECT OF TEMPERATURE ON ELECTROLYTE METABOLISM OF ISOLATED FROG SKIN
Authors: Huf Ernst G. , Doss Norma S. 
Published: May 2004

A study is presented on the effect of temperature on unidirectional active ion transport, resting electrolyte equilibrium (electrolyte composition), and oxygen consumption in isolated frog skin. The aims were twofold: first, to find out whether the rate of active transport can be changed without affecting the Na+ and K+ balance of skin itself; second, to arrive at minimal ΔNa/ΔO2 values by correlating quantitatively inhibition of active ion transport with inhibition of O2 consumption. NaCl transport was maximal at 20°C. At 28° and at temperatures below 20°, rate of NaCl transport was diminished. In many instances NaCl transport was diminished in skins which maintained their normal Na+ and K+ content. In several cases, however, neither rate of transport nor resting electrolyte equilibrium was affected; in other cases, both were.
O2 consumption decreased when lowering the temperature over the range from 28 to 10°C. From a plot of log QOO2 against 1/T an activation energy of µ 13,700 cal. was calculated, valid for the range from 10 to 20°C. It appeared that µ was smaller for temperatures above 20°C. Working between 10 and 20°, it was found that, on the average, 4 to 5 equivalents of Na+ were transported for one mole of O2 consumed in skins with undisturbed resting electrolyte equilibrium.
THE INFLUENCE OF THE MEDIUM DIELECTRIC STRENGTH UPON TRYPSIN KINETICS
Authors: Castañeda-Agulló M. , del Castillo Luz M. 
Published: May 2004

The use of aqueous alkali for the titration of esterolytic activity when the esters are dissolved in alcoholic solutions, results in an error due to changes in the ionization of the buffer. This is corrected by titrating with alkali in the same solvent as the substrate.
Alcohols and other substances which change the dielectric strength of water modify the rate of hydrolysis of BAEE1 and TSAME by trypsin to an extent proportionate to their effect on the dielectric strength. The reaction rate increases with diminished dielectric strength and vice versa. At low concentrations of substance there seems to be no specific effect other than that derived of the variation in dielectric strength. At higher concentrations, the enzyme might be denatured. In addition, it is probable that specific effects of each substance might intervene. The Coulombic and thermic energies of activation were calculated for the two esters in various solvents. The plot of the logarithm of rate constant vs. reciprocal of dielectric constant yields a straight line with positive slope. This behavior is similar to that of a non-enzymatic positive ion-dipole reaction. Trypsin reacts like a positive ion. The possible influence of the dielectric strength on the regulation of the equilibria involved in the interconversion of the various forms of trypsin in solution (active, inactive, denatured) is discussed.
GROWTH DISTRIBUTION IN THE LIGHT-GROWTH RESPONSE OF PHYCOMYCES
Authors: Castle Edward S. 
Published: May 2004

Elongation of sporangiophores marked with numerous starch grains was photographically recorded in the steady state and during the light-growth response when the rate is more than doubled. From these records the spatial distribution of growth within the cell's growth zone was derived.
Stimulation by a single saturating flash of light speeds growth proportionally in all parts of the growing zone, maintaining the same pattern of growth distribution as in the steady state. This finding implies that light is absorbed and acts locally throughout the length of the cell's growth zone. Cohen and Delbrück's proposal of a partial spatial separation of light reception and growth is discussed.
A LIGHT-SENSITIVE YELLOW PIGMENT FROM THE HOUSE-FLY
Authors: Bowness J. M. , Wolken J. J. 
Published: May 2004

Extraction of house-fly heads with neutral phosphate buffer yielded a dark brown solution from which a number of pigments were separated, either wholly or partially, by chromatography on a column of calcium phosphate mixed with celite. One of the pigments was light-sensitive, and had a yellow color, with a spectral absorption maximum at 437 mµ in phosphate buffer at pH 6.5. Several consecutively eluted fractions from each chromatogram of the house-fly head extract showed the characteristic absorption curve of this pigment with no trace, spectroscopically, of the other pigments of the extract. The products of bleaching the pigment at pH 6.5 had an absorption curve showing plateaus at 440 to 460 mµ and 350 to 360 mµ and an inflection at about 250 mµ. Above pH 8.0 the pigment bleached in the dark giving an absorption maximum at about 380 mµ, and inflections at 290 mµ and at about 250 mµ. With 2.5 to 5 N HCl or H2SO4 an absorption maximum at 470 to 475 mµ was obtained with either the unbleached or the bleached pigment. With sulfosalicylic acid, ethanol, or heating at 100°C., a part of the pigment was precipitated, leaving a light-stable yellow supernatant.
This light-sensitive house-fly pigment cannot as yet be identified with any of the previously known insect pigments or with the photosensitive pigments of other animals, though these latter compounds exhibit some similarity in their spectroscopic properties.
SYNAPTIC COMPONENTS OF CEREBELLAR ELECTROCORTICAL ACTIVITY EVOKED BY VARIOUS AFFERENT PATHWAYS
Authors: Purpura D. P. , Girado M. , Grundfest H. 
Published: May 2004

Electrical responses evoked in different regions of the cerebellar cortex of cat by stimulating various cerebello-petal pathways have been analyzed for their component postsynaptic potentials (p.s.p.'s). The principal analytical tools of the present work were pharmacological agents; the selective inactivator of depolarizing (excitatory) axodendritic synapses, γ-aminobutyric acid (GABA, or C4); the homologous C6 and C8 ω-amino acids, which inactivate selectively the hyperpolarizing (inhibitory) axodendritic synapses; and the general inactivator of inhibitory synapses, strychnine. Some experiments employed the analytical possibilities of activity cycles.
The potentials evoked in one cerebellar region by different exciting pathways may differ markedly in their responses to drugs or may show different types of activity cycle. Also, the potentials evoked in various cortical regions by one cerebello-petal pathway are acted upon differently by the testing drugs. These differences are believed to be due to involvement of different proportions of excitatory and inhibitory, axosomatic and axodendritic p.s.p.'s. The analyses of a number of different responses confirm an earlier conclusion, that the cerebellar cortex is relatively lacking in inhibitory axodendritic p.s.p.'s in comparison with the cerebral cortex. Only the cortex of the paramedian lobule appears to be endowed with a considerable proportion of inhibitory p.s.p.'s, a finding which correlates with other data.
PARAMETERS OF GASEOUS ION EFFECTS ON THE MAMMALIAN TRACHEA
Authors: Krueger Albert P. , Smith Richard F. 
Published: May 2004

A. Duration of Effects
Groups of mice exposed to high densities of unipolar light air ions for 72 hours exhibited persistent alterations in the functional efficiency of their tracheas. These effects lasted at least 4 weeks, and in the case of animals treated with (+) ions included diminished ciliary activity, pale and contracted tracheal mucosa, and enhanced vulnerability to trauma.
Following treatment with (-) ions, animals displayed increased ciliary activity with no other detectable changes. It required at least 60 minutes of exposure to ions to induce such "permanent" functional changes.
B. Minimal Effective Ion Densities
The minimal ion densities producing changes in ciliary activity within an arbitrary period of 30 minutes were determined with extirpated tracheal strips from rabbits and guinea pigs. The threshold value for (-) ions was approximately 2.5 x 103 ions/cm.2/sec. and that for (+) ions was in the range between 1 x 104 and 2.5 x 105 ions/cm.2.
The minimal ion densities producing changes in ciliary activity within an arbitrary period of 30 minutes were determined with extirpated tracheal strips from rabbits and guinea pigs. The threshold value for (-) ions was approximately 2.5 x 103 ions/cm.2/sec. and that for (+) ions was in the range between 1 x 104 and 2.5 x 105 ions/cm.2.
The evidence indicates that ion-induced functional changes in the ciliated epithelium of the pulmonary tree are the results of direct contact of ions with surface cells and do not involve participation of the central nervous system or circulation. So far as ciliary activity is concerned, the number of ions required to produce a change in rate is very small.
PROTOPLASMIC STREAMING OF AN INTERNODAL CELL OF NITELLA FLEXILIS
Authors: Kishimoto Uichiro , Akabori Hiromichi 
Published: May 2004

The sudden cessation or sudden decrease in velocity of the protoplasmic streaming of Nitella flexilis is observed whenever an action potential is elicited. The action potential can be generated by an electric stimulus after its refractory period, whether the flow is at a complete standstill or on the way to recovery. The membrane potential is generally decreased more or less when the rate of flow is decreased on application of salts or other agents. There is, however, no parallelism between these two. The membrane potential decreases proportionally with applied voltage of subthreshold intensity, while the rate of flow does not change appreciably. Only on application of a superthreshold voltage does the flow stop suddenly. In one case the rate of flow decreased to half without appreciable decrease in membrane potential. In another case it continued flowing at about one-half rate, although the membrane potential was almost zero. The Q10 of the rate of flow is about 2, while it is 1.1 to 1.5 for the membrane potential.
The sudden cessation of the protoplasmic streaming is supposed to be caused by the temporary formation of certain interlinkages among contractile protein networks in the endoplasm during excitation at the cathodal half of Nitella.
THE POTENTIAL OF WATER IN MAMMALIAN TISSUES
Authors: Maffly Roy H. , Leaf Alexander 
Published: May 2004

Melting point depression was used as an index of the water potential of rat tissues and serum. Organs removed from anesthetized rats were immediately frozen in liquid nitrogen and ground with mortar and pestle. Aliquots of the resulting frozen powder were suspended in chilled liquid silicone. While the suspension was vigorously stirred and warmed at a constant rate, the temperature of the melting mixture was measured.
The melting curves of rat muscle, liver, heart, and brain were not significantly different from those of rat serum. The melting curve depression of whole kidney was greater than that of serum; this was demonstrated to be due to hypertonicity of the renal medullary area alone. It was demonstrated that autolysis will rapidly increase the depression of the melting curve of tissue. It is concluded that within the limits of the method used the melting point depression, and hence the water potential, of intracellular and extracellular fluids is the same.
SODIUM AND POTASSIUM BINDING BY RAT LIVER CELL MICROSOMES
Authors: Sanui Hisashi , Pace Nello 
Published: May 2004

The effects of ion concentration, pH, and presence of competing ions on the sodium and potassium binding properties of rat liver cell microsomes were studied. Typical adsorption isotherms were obtained in the concentration dependence studies, with saturation being reached when 1.2 to 1.4 m.eq. cations were retained per gm. of microsome Kjeldahl nitrogen. The retention was shown to be due to a binding to specific sites rather than to a trapping of the cations. The binding showed a sharp pH dependence in the range 6.0 to 7.5. The presence of one cation depressed the binding of the other, indicating that Na+ and K+ as well as H+ ions compete for the same sites. Potassium was bound slightly more strongly than sodium, while hydrogen was bound about 105 times more strongly than either. Calculations show that the binding follows the simple mass law.
Similarities between adsorption by microsomes and adsorption by synthetic cation exchange resins are discussed and compared to some of the characteristics of electrolyte behavior in living systems. A possible ion exchange elution, active cation transport mechanism is suggested, involving the preferential elution of Na+ out of the cell by H+ ions produced by metabolism.
Potassium Accumulation and Sodium Efflux by Porphyra perforata Tissues in Lithium and Magnesium Sea Water
Authors: Eppley Richard W. 
Published: May 2004

Cells of Porphyra perforata, a red marine alga, accumulate K in the absence of concomitant Na or Li extrusion while immersed in Li- or Mg-sea waters lacking Na. This suggests that the coupling observed between K and Na transport is facultative. No evidence is obtained for net extrusion of Li.
Na efflux, with the concentration gradient, is facilitated by K and is proportional to the cellular Na content. Either Na efflux does not involve an ion carrier or the number of Na sites is large.
Because K accumulation has been observed in the absence of Na extrusion, but not vice versa, it seems that K uptake is the primary secretory event, with Na extrusion a secondary process dependent upon K accumulation.
Muscle: A Three Phase System
Authors: Frater R. , Simon Shirley E. , Shaw F. H. 
Published: May 2004

The partition of sulfate, Ca++, and Mg++ across the membrane of the sartorius muscle has been studied, and the effect of various concentrations of these ions in the Ringer solution on the cellular level of Na+, K+, and Cl- has been determined.
The level of the three divalent ions in toad plasma and muscle in vivo has been assayed. Muscle was found to contain an almost undetectable amount of inorganic sulfate.
Increases in the external level of these ions brought about increases in intracellular content, calculated from the found extracellular space as determined with radioiodinated serum albumin or inulin. Less of the cell water is available to sulfate than to Cl-, and the Mg++ space is less than the Na+ space. An amount of muscle water similar to that found for Li+ and I- appears to be available to these divalent ions. Sulfate efflux from the cell was extremely rapid, and it was not found possible to differentiate kinetically between intra- and extracellular material.
These results are consistent with the theory of a three phase system, assuming the muscle to consist of an extracellular phase and two intracellular phases. Mg++ and Ca++ are adsorbed onto the ordered phase, and increments in cellular content found on raising the external level are assumed to occur in the free intracellular phase.
Radiocalcium Release by Stimulated and Potassium-Treated Sartorius Muscles of the Frog
Authors: Shanes A. M. , Bianchi C. P. 
Published: May 2004

Stimulation of frog (Rana pipiens) sartorius muscle accelerates release of Ca45, but only during the period of stimulation. No appreciable difference is obtained in the calcium released per impulse whether stimulation is at a rate of 20/sec. or 0.5/sec. However, prior stimulation may appreciably increase the loss per impulse. In unfatigued muscles, the minimum amount of calcium liberated during an isotonic twitch is estimated to be about that previously calculated to enter, viz. 0.2 µµmole/cm2.
The time course of radiocalcium release during potassium depolarization depends on the nature of the contracture. When contracture is isometric, the rate of escape is doubled and declines only slowly; if isotonic, the rate is quadrupled but declines in a few minutes to a level maintained at about double that before potassium. The minimal calcium release during the first 10 minutes of potassium treatment is estimated to be about the same in both cases and about one-half to one-third the uptake. This, and especially the close equality of calcium entry and exit during electrical stimulation, are pointed out as not necessarily inconsistent with a transitory net entry of calcium, comparable to the influx, into restricted regions of the individual fibers.
Studies on the Distribution of Factor I and Acetylcholine in Crustacean Peripheral Nerve
Authors: Florey Ernst , Biederman M. A. 
Published: May 2004

Extracts of whole nerve (chelipeds of Cancer magister) cause inhibition of impulse generation of the crayfish stretch receptor preparation, similar to that produced by gamma-aminobutyric acid (GABA). This is not found with extracts containing only sensory or sensory and motor fibers. Extracts of inhibitory fibers inhibit the stretch receptor discharge—indicating an inhibitory action equivalent to that of up to 30,000 micrograms of GABA per gm. wet weight of inhibitor fiber. This high value is taken as an indication that the inhibitory substance in crab inhibitory fibers is not identical with gamma-aminobutyric acid.
Whole nerves were found to contain 1.7 to 6.7 µg. acetylcholine per gm. nerve tissue (clam ventricle and frog rectus abdominis muscle). No acetylcholine could be detected in extracts of motor and inhibitory fibers. The acetylcholine content of sensory fibers can account for the acetylcholine activity of whole nerve extract.
It is concluded that the factor I of crustacean nerve is an exclusive property of the inhibitory fibers. The results support the assumption that factor I is the transmitter substance of inhibitory neurons in these animals.
The absence of acetylcholine in motor fibers indicates that this substance does not function as a transmitter of motor impulses in Crustacea, and explains the previously observed failure of the substance to elicit motor responses in these animals. The function of acetylcholine in sensory fibers is not yet clarified.
The Biological Mechanisms of Air Ion Action
Authors: Krueger Albert P. , Smith Richard F. 
Published: May 2004

Intravenous administration of 5-hydroxytryptamine to rabbits and guinea pigs is shown to bring about changes very similar to those produced by (+) air ions, including (1) decreased ciliary rate, (2) contraction of the posterior tracheal wall, (3) exaggerated response of the tracheal mucosa to trauma, (4) marked vasoconstriction in the tracheal wall, and (5) increased respiratory rate. These effects are reversed by (-) air ions. Iproniazid, which raises 5-hydroxytryptamine levels in the animal by blocking monamine oxidase, produces similar but non-reversible effects. Reserpine, which depletes 5-hydroxytryptamine in the animal, causes changes that resemble those produced by (-) air ions, including (1) increased ciliary rate, (2) relaxed posterior sulcus, (3) hyperemia of the tracheal mucosa, (4) lowered respiratory rate, and (5) increased volume and rate of mucus flow.
On the basis of these facts, the hypothesis is advanced that (+) air ion effects are mediated by the release of free 5-hydroxytryptamine, while (-) air ion effects depend on the ability of (-) ions to accelerate the enzymatic oxidation of 5-hydroxytryptamine.
Photoreactivation of Transforming DNA by an Enzyme from Bakers' Yeast
Authors: Rupert Claud S. 
Published: May 2004

Ultraviolet-inactivated Hemophilus influenzae transforming DNA recovers its activity when mixed with cell-free extracts of bakers' yeast and exposed to visible light. The active agent in the extract is not used up in the reaction, and purification has not separated it into more than one non-dialyzable component. It differs from the agent in Escherichia coli extract, which produces very similar photoreactivation, but which can be resolved into non-dialyzable and dialyzable components, the latter being used up during illumination.
The yeast agent can be salted out of solution and recovered quantitatively; it is inactivated by crystalline trypsin and chymotrypsin and by brief heating at 60°C.—all facts suggesting that it is an enzyme for which ultraviolet lesions in the DNA serve as substrate. The kinetics of recovery are also consistent with such an assumption.
This enzyme is unusual both because it is involved in a light-dependent reaction and because it has a non-destructive action on DNA outside an intact cell.