bluuebunny/crossref_metadata_2025 huggingface dataset:
Na Extrusion by the Sartorius of Rana pipiens
Authors: Steinbach H. Burr
Published: May 2004

Sartorius muscles of R. pipiens may be enriched in sodium and depleted of potassium by prolonged soaking in the cold in K-free or low K Ringer's solution. Such K-depleted muscles take up potassium and extrude sodium when exposed to Ringer's solution containing 10 mM K at ordinary room temperature (ca. 20°C), with no dependence on external Na ion concentration in either phase within fairly wide limits.

Extrusion of excess fiber Na is demonstrated on single muscles using Na24-loaded tissues. Rate of exchange of excess fiber Na does not differ significantly from the rate of exchange of Na normally present in muscle fibers.
Photoreactions in Phycomyces
Authors: Delbrück M. , Varjú D.
Published: May 2004

Equipment has been developed for ultraviolet illumination of sharply bounded test areas of the growing zone of sporangiophores of Phycomyces. The growing zone is opaque for this light and the tropic responses are negative. Periodic short narrow stimuli on alternating sides produce periodic tropic responses when applied at x > 0.5 mm, but none for x < 0.5 mm, where x is the distance below the sporangium. Sustained tropic stimuli, applied at constant x, produce tropic responses for any x > 0.1 mm. The lag between stimulus and response is 3.3 min. for any x > 0.5 mm. For smaller x the lag increases progressively. In all cases the tropic bend occurs at values of x > 0.5 mm. Sustained tropic stimuli, applied at constant height relative to ground, produce relatively sharp tropic bends. The center of the bend is at all times close to the simultaneous position of the stimulated area. The boundaries of a light-adapted zone move less than 0.1 mm in 10 min. relative to the sporangium. It is concluded that the receiving and adapting structures do not move relative to the sporangium, and that the responding system does not move relative to ground. The two systems move relative to each other with the speed of growth. The responding system does not extend above x = 0.5 mm.
Studies on Transformations of Hemophilus influenzae
Authors: Goodgal Sol H. , Herriott Roger M.
Published: May 2004

The sedimentation and diffusion coefficients have been determined for Hemophilus influenzae transforming activity and DNA using P32-labeled DNA. The methods employed the Spinco fixed boundary separation cell for measurements of the sedimentation coefficient and the Northrop-Anson diffusion cell to determine the diffusion coefficient. There was a very close correlation between the amount of DNA and transforming activity sedimented or diffused. The sedimentation coefficient (s20°), for both biological activity and DNA was 27 and the diffusion coefficient (D20°) 1 x 10-8 cm2/sec. The molecular weight calculated from these coefficients gave a value of 16 million. There was no difference in the sedimentation coefficients for the two unlinked markers, streptomycin and erythromycin resistance, and the diffusion coefficients for single markers or the linked markers, streptomycin and cathomycin, were the same.
Studies on the Flight Mechanism of Insects
Authors: McCann Frances V. , Boettiger Edward G.
Published: May 2004

Fibrillar type flight muscle powers the flight machinery of the more phylogenetically advanced groups of flying insects. A comparison of responses from single fibers in insects from various orders having fibrillar muscle reveals fundamental differences. In single fibers of flies and wasps the response to a single threshold stimulus is an all-or-none, uniformly rising, in most cases overshooting action potential. Beetles give variable responses, some of which appear similar to the type mentioned above, and others which summate and facilitate. Some of the latter responses vary with time in a cyclic manner, and some are altered by the intensity of the stimulus. Further differences appear when the two types of muscle are exposed to ether and carbon dioxide. In the wasp and fly ether produces a neuromuscular block, while CO2 effects a rapid depolarization of the resting fiber membrane. Both reactions are completely reversible. The electrical responses of beetle muscle are somewhat affected but only by massive doses. The implications of these data are discussed relative to the existence of fibrillar muscle "types."
A Physical Interpretation of the Phenomenological Coefficients of Membrane Permeability
Authors: Kedem O. , Katchalsky A.
Published: May 2004

A "translation" of the phenomenological permeability coefficients into friction and distribution coefficients amenable to physical interpretation is presented. Expressions are obtained for the solute permeability coefficient ω and the reflection coefficient σ for both non-electrolytic and electrolytic permeants. An analysis of the coefficients is given for loose membranes as well as for dense natural membranes where transport may go through capillaries or by solution in the lipoid parts of the membrane. Water diffusion and filtration and the relation between these and capillary pore radius of the membrane are discussed. For the permeation of ions through the charged membranes equations are developed for the case of zero electrical current in the membrane. The correlation of σ with ω and Lp for electrolytes resembles that for non-electrolytes. In this case ω and σ depend markedly on ion concentration and on the charge density of the membrane. The reflection coefficient may assume negative values indicating anomalous osmosis. An analysis of the phenomena of anomalous osmosis was carried out for the model of Teorell and Meyer and Sievers and the results agree with the experimental data of Loeb and of Grim and Sollner. A set of equations and reference curves are presented for the evaluation of ω and σ in the transport of polyvalent ions through charged membranes.
A Persistent Daily Rhythm in Photosynthesis
Authors: Hastings J. Woodland , Astrachan Lazarus , Sweeney Beatrice M.
Published: May 2004

The luminescent marine dinoflagellate, Gonyaulax polyedra, exhibits a diurnal rhythm in the rate of photosynthesis and photosynthetic capacity measured by incorporation of C14O2, at different times of day. With cultures grown on alternating light and dark periods of 12 hours each, the maximum rate is at the 8th hour of the light period. Cultures transferred from day-night conditions to continuous dim light continue to show the rhythm of photosynthetic capacity (activity measured in bright light) but not of photosynthesis (activity measured in existing dim light). Cultures transferred to continuous bright light, however, do not show any rhythm. Several other properties of the photosynthetic rhythm are similar to those of previously reported rhythms of luminescence and cell division. This similarity suggests that a single mechanism regulates the various rhythms.
Active Ion Transport Across Canine Blood Vessel Walls
Authors: Sawyer Philip N. , Levine Joel , Mazlen Roger , Valmont Ignatius
Published: May 2004

Experiments giving evidence of active Na and Cl ion fluxes across large canine blood vessel walls (aorta, vena cava) in vitro have been presented. The information has been obtained using ion tracer techniques after Ussing and with diffusion cells of the Hogben type. The available data suggest that the membranes are satisfactorily oxygenated by the bathing solutions saturated with oxygen at atmospheric pressure. Evidence is offered which indicates that active ion transport does occur across the aorta and vena cava in in vitro experiments. Under the conditions of the experiment net Na and Cl flux takes place from intima to adventitia across the aorta, and from adventitia to intima across the vena cava at low measured potential differences. The possible relationships of derangement of active ion transport mechanisms, produced by electric currents and tissue injury potential differences, to intravascular thrombosis are alluded to. It would appear that sodium and chloride fluxes across large blood vessel walls in vitro occur at least in part as the result of metabolic processes and cannot be explained simply on the basis of diffusion across a semipermeable membrane.
The Effect of Exogenous Energy Sources on the Synthesis of ß-Galactosidase in Resting-Cell Suspensions of Escherichia coli
Authors: Palmer I. S. , Mallette M. F.
Published: May 2004

Using methyl-1-thio-ß-D-galactoside as the inducer, the biosynthesis of ß-galactosidase was observed in Escherichia coli B with only endogenous sources of nitrogen and energy available. The addition of glucose, ribose, xylose, or glycerol as exogenous energy sources to nitrogen-deficient media blocked enzyme formation. Preinduction of the resting cells failed to overcome inhibition by the added energy sources. With limited quantities of glucose, ribose, xylose, or glycerol, synthesis of ß-galactosidase resumed abruptly and continued at the rate normal for cells in nitrogen-deficient media. Comparison of enzyme activities with oxygen uptake data revealed a reduction in the rate of oxygen uptake at the time enzyme synthesis resumed in media originally containing small amounts of energy sources. This change corresponded to only a fraction of the oxygen required for complete oxidation of one of the exogenous substrates. It is suggested that inhibition by these particular exogenous substrates involves metabolism to a common repressor or interference with an energy-transfer system.
Cation Transport in Escherichia coli
Authors: Schultz Stanley G. , Solomon A. K.
Published: May 2004

Methods have been developed to study the intracellular Na and K concentrations in E. coli, strain K-12. These intracellular cation concentrations have been shown to be functions of the extracellular cation concentrations and the age of the bacterial culture. During the early logarithmic phase of growth, the intracellular K concentration greatly exceeds that of the external medium, whereas the intracellular Na concentration is lower than that of the growth medium. As the age of the culture increases, the intracellular K concentration falls and the intracellular Na concentration rises, changes which are related to the fall in the pH of the medium and to the accumulation of the products of bacterial metabolism. When stationary phase cells, which are rich in Na and poor in K, are resuspended in fresh growth medium, there is a rapid reaccumulation of K and extrusion of Na. These processes represent oppositely directed net ion movements against concentration gradients, and have been shown to be dependent upon the presence of an intact metabolic energy supply.
Electrophysiological Studies of a Water Receptor Associated With the Taste Sensilla of the Blowfly
Authors: Evans David R. , Mellon Deforest
Published: May 2004

Electrophysiological evidence is given that water is the specific stimulus for a fourth sensory cell associated with the taste sensilla of the blowfly. Water elicited impulses from a single cell which responded in two distinct phases: an initial rapid rate of discharge followed by a lesser, sustained steady rate. The latter, in the case of sucrose solutions, was inhibited in direct proportion to the log of the osmotic pressure over a 104 range of pressures. Other non-electrolytes inhibited, but the effect could not be simply correlated with parameters of the solutions. Electrolytes inhibited the water response more sharply and at lower concentrations. The inhibition in all cases was not dependent on impulses in the other sensory cells of the taste sensillum.
The Electrical Potential Profile of the Isolated Toad Bladder
Authors: Frazier Howard S.
Published: May 2004

The electrical potential profile of the isolated toad bladder was examined in the spontaneously active, chronically short-circuited, and intermittently short-circuited states by means of glass micropipettes. The position of the micropipette tip within the bladder was evaluated by measuring the D.C. resistance between the micropipette tip and the reference electrode on the serosal side of the bladder. In the spontaneously active state, with concentrations of sodium in the mucosal solution ranging from less than 1 to 114 meq per liter, the potential profile consisted in the majority of impalements of two steps, each positive to the mucosal solution. A minority of impalements showed more than two potential steps, each positive to the mucosal solution. In the short-circuited state, the interior of the bladder was found to be negative to the bathing solution by approximately 5 mv. The results are interpreted as showing a potential step at the two surfaces of the epithelial cell layer of the toad bladder. In the spontaneously active state the potential change at the mucosal boundary is of the wrong polarity to bring about net sodium entry; the small electrical driving force across the mucosal surface which is present in the short-circuited state may contribute to the net entry of sodium from mucosal solutions with low sodium concentration.
Potassium Loss during Galvanotaxis of Slime Mold
Authors: Anderson John D.
Published: May 2004

The posterior reticulated regions of the plasmodia of the slime mold, Physarum polycephalum, whose migration has been oriented by direct current (3.0 to 5.0 µa/mm2 in the agar substrate), contain 30 per cent less potassium than the advancing non-reticulated region. The anterior regions have the same potassium concentration as that of the controls, approximately 32 meq/kg wet weight. Differences in potassium concentration between anterior and posterior regions of control plasmodia, not oriented by electric current, are less than 5 per cent. Sodium, in contrast to potassium, is generally less concentrated in the anterior than in the posterior regions of electrically oriented plasmodia, but sodium concentrations are extremely variable. No significant difference in protein concentration was found between oriented and control plasmodia. Thirty-five per cent of the total potassium, but none of the sodium, is found in acidified ethanol precipitates from plasmodial homogenates. Potassium, but not sodium, appears to be closely associated with processes which differentiate anterior from posterior in an oriented plasmodium.
Serotonin in the Developing Mammal
Authors: Pepeu G. , Giarman N. J.
Published: May 2004

Determinations have been made of the level of serotonin in various fetal and maternal tissues of goats and rabbits. In the goat, both fetal brain and blood were higher in serotonin content than comparable maternal tissues. Furthermore, in the goat fetal neocortical areas unexpectedly were found to be richer in serotonin than certain subcortical structures. In contrast to the goat, the rabbit was shown to have higher serotonin levels in maternal than in fetal blood. Moreover, when a large amount of serotonin was administered subcutaneously to pregnant rabbits, the fetuses began to die at a time when the maternal blood levels of serotonin had about doubled. This toxic action was shown to be due at least partially to the sensitivity of the umbilical vessels to the vasoconstrictor action of serotonin.
The Isolation of Colicine V and a Study of Its Immunological Properties
Authors: Hutton John J. , Goebel Walther F.
Published: May 2004

Colicine V has been obtained from the culture medium in which the colicinogenic bacillus E. coli K357 L_T is grown. The material is electrophoretically homogeneous and proves to be a lipocarbohydrate protein complex identical with the type-specific O antigen of the parent bacillus. Colicine V is toxic both for mice and for rabbits and readily stimulates the elaboration of precipitins and bacterial agglutinins, as well as antibodies which neutralize the antibacterial activity of the colicine itself. The colicine is also toxic for certain strains of Enterobacteriaceae. Although colicine V and colicine K, previously described in this laboratory, have many properties in common, they exhibit no cross-serological relationship whatsoever.
The Amino Acid Composition of Human Pituitary Growth Hormone
Authors: Dixon Jonathan S. , Li Choh Hao
Published: May 2004

The amino acid content in human hypophyseal growth hormone has been determined by chromatography on resin columns. On the basis of 29,000 for the molecular weight, the empirical formula of the hormone was obtained: lys13his5arg14asp27 thr14ser23glu34pro12gly13ala12-(1/2 cys)6val12met4-ileu10leu31tyr10phe15try1(NH3)32.
Hydrolysis of Irradiated Ovalbumin by Pepsin
Authors: Dieu Hector A. , Desreux V.
Published: May 2004

Solid ovalbumin has been irradiated at three doses, 6.5, 25, and 40 megarads, under high vacuum. The native and irradiated samples have been hydrolyzed at pH 1.4 by pepsin, after centrifugation of the aggregates, if necessary. The number of bonds broken per ovalbumin molecule has been estimated by comparing the rate of protein destruction with the rate of formation of NH2 groups. Both rates increase very much with the dose, but the number of bonds broken decreases. Sedimentation measurements show a strong shape modification of the soluble fraction in the case of the 25 and 40 megarad samples. The increase in asymmetry is bound to the increase in the rate of attack on γ-irradiated ovalbumin by pepsin. Infrared spectra of the aggregates show small difference from those of the native samples.
The N-Terminal Amino Acids of Human Plasma Proteins
Authors: Niall Hugh , Edman Pehr
Published: May 2004

A study has been made of the N-terminal amino acid pattern of human plasma proteins under normal and pathological conditions. The normal pattern shows the following N-terminal amino acids in order of diminishing quantities: aspartic acid, glutamic acid, valine, alanine, tyrosine, leucines, and glycine. In healthy individuals this pattern is qualitatively stable with moderate quantitative differences between individuals. On the other hand radical quantitative changes in the pattern have been observed under pathological conditions.
Some Seismic Profiles near the Western End of the Puerto Rico Trench
Authors: Northrop John , Ransone Morris
Published: May 2004

A cooperative program of seismic refraction profiling was completed in the vicinity of the Puerto Rico Trench by Hudson Laboratories, Woods Hole, Lamont, and Texas A. & M. Profiles completed near the western end of the Trench were analyzed at Hudson Laboratories. Five seismic layers are indicated below the water layer. The thickness/velocity relationships are as follows: 5.1 km of 1.5 km/sec. (water); 1 km of 1.7 km/sec. (sediment); 1.5 km of 3 km/sec. (metamorphics?); 2 km of 5.5 km/sec. (basement); and 2 km of 7.1 km/sec. (high speed basement). Below these, typical Moho velocities of 8.1 km/sec. were measured. Total depth to Moho ranges from 9 to 12 km below sea level, the greatest variation occurring in the basement layers. The least depth was measured 65 miles north of the Puerto Rico Trench.
Hydrolysis of Adenosine Triphosphate by Crystalline Yeast Pyrophosphatase
Authors: Kunitz M.
Published: May 2004

Schlesinger and Coon's report that crystalline yeast inorganic pyrophosphatase, in addition to its known ability to hydrolyze inorganic pyrophosphate in the presence of Mg ions, is also able to catalyze the hydrolysis of ATP and ADP in the presence of Zn ions was confirmed. A systematic study showed that the ratio of 370 of PPase-Mg over ATPase-Zn activities per milligram protein in various preparations of pyrophosphatase obtained in the course of isolation of crystalline pyrophosphatase from baker's yeast was nearly identical in all the preparations, independent of their purity. The course of hydrolysis of ATP by crystalline pyrophosphatase in the presence of Zn was carried out with the aid of ion exchange on Dowex 1. The finding of Schlesinger and Coon that the hydrolysis proceeds from ATP to ADP and then slowly to AMP was confirmed. The kinetics of the first phase of the reaction was found to depend on the molar ratio of Zn/ATP in the reaction mixture. Mg ions in the presence of Zn ions have an accelerating effect on the rate of hydrolysis of ATP. This suggests strongly that both activities—ATPase and PPase—are manifestations of the same active group in the protein molecule of crystalline pyrophosphatase.
Stimulation of a Primary Taste Receptor by Salts
Authors: Evans David R. , Mellon DeForest
Published: May 2004

A quantitative study was made of the repetitive response of the salt receptor cell of the blowfly taste receptor. The response begins at a high frequency and declines to a steady frequency during brief stimuli. The initial response was found to be a sigmoid function of the log of stimulus intensity over a short range of intensities. It was shown that a theory (Beidler, 1954; for mammalian salt receptors) that relates the magnitude of the steady response to stimulus intensity applies to this receptor. From the theory, it was calculated that the relative free energy change of the reaction between salt and receptor site was in the range 0 to -1 kcal/mole; and, therefore, the reaction probably involves weak physical forces. Evidence is given that the salt-combining sites of the receptor are anionic and strongly acidic and that consequently the cation of a salt largely dominates stimulation. Preliminary evidence suggests that the receptor has a high degree of specificity toward salts, being stimulated primarily by monovalent inorganic cations.
Spike Potentials Recorded from the Insect Photoreceptor
Authors: Naka Kén-Ichi , Eguchi Eisuke
Published: May 2004

Slow and spike potentials were recorded from single cells in the receptor layer of the compound eye of the drone of the honeybee. From electron microscopic observation of the drone ommatidium, it was concluded that the response had been recorded from the retinula cell. The following hypothesis is suggested for the initiation of spike potentials in the drone compound eye: Photic stimulation results in a decrease in the resistance of all or part of the retinula cell membrane, giving rise to the retinal action potential. The retinal action potential causes outflow of the current through the proximal process of the cell. This depolarizing current initiates spike potentials in the proximal process or axon of the retinula cell which are recorded across the soma membrane of the retinula cell.
Deoxyribonuclease from Salmon Testes
Authors: McDonald Margaret R.
Published: May 2004

A procedure is described for the purification of salmon testis deoxyribonuclease II by means of acid extraction, fractional precipitation with ammonium sulfate, heat denaturation of extraneous proteins, and ethanol fractionation. This process separates the deoxyribonuclease activity from that of ribonuclease, phosphatase, phosphodiesterase, and protease. Over 50 per cent of the activity is retained with an over-all enrichment of 20,000-fold. The enzyme degrades both native and heat-denatured DNA, but the rate of degradation of the latter is only one-tenth that of the former. It does not hydrolyze apurinic acid.

The enzyme is most stable in the pH range 4 to 5. Electrolytes are essential for the expression of its activity: monovalent ions satisfy the requirement, but divalent ones are much more effective. Above a certain optimum concentration, each electrolyte is inhibitory. The pH of maximal activity, under conditions of optimal ionic strength, is 4.8; the temperature optimum is near to 55°C.
Temperature Effects on Day Old Drosophila Pupae
Authors: Milkman Roger
Published: May 2004

Day old Drosophila pupae were subjected to a variety of closely controlled temperature shocks. Twenty-five hours after puparium formation (at 23°), temperatures from 39.5–41.5° (Q1 = 2.3) differentially disturb the formation of the posterior crossvein. Three other separate treatments disturb posterior crossvein formation: treatments in the range 36.0–37.0° at 25 hours; 37.3–37.8° at 25 hours; and 39.5–41.5° at 19 hours. Certain qualitative effects are associated with certain temperatures: elliptical holes are seen in wings of flies exposed 25 hours after puparium formation to temperatures from 37.3–37.8°. Anterior crossvein defects ensue if animals are similarly exposed to temperatures from 37.9–38.2°. Within the physiological range, animals raised at higher temperatures are more resistant to the effects of temperatures at 39.5–41.5°. An extremely rapid temperature adaptation by exposures to temperatures in the range 31–38° results in markedly greater resistance to heat shock; here resistance to production of crossvein defects increases faster than to death. The association between qualitative effects and treatment temperatures is modified by changing the temperature at which the animals spend their first day of pupal life. Summation experiments support conclusions drawn from the simpler experiments. Genetic variation and interspecific variation are discussed in the present context, as well as implications of the role of protein denaturation in the biological effects of high temperatures and further, more general experiments.
Permeability of Luminal Surface of Intestinal Mucosal Cells
Authors: Lindemann B. , Solomon A. K.
Published: May 2004

A method has been devised to measure the permeability characteristics of the intestinal mucosal cells in the rat. The method makes use of an electrical recording balance to register changes in weight when the mucosal face of a small strip of intestine is exposed to anisotonic solutions. The permeability coefficient of the luminal surface of intestinal mucosal cells to water is measured as 0.15 cm4/OSM, sec. and reasons are adduced to suggest that the true value might be higher than this. The equivalent pore radius of the luminal face of the tissue, measured in experiments in which lipid-insoluble non-electrolytes have been used according to the method of Goldstein and Solomon, appears to be 4.0 Å.
Tubular Transport Maxima of PAH and Diodrast Measured Individually in the Aglomerular Kidney of Lophius, and Simultaneously as Competitors Under Conditions of Equimolar Loading
Authors: Forster Roy P. , Hong Suk Ki
Published: May 2004

The maximal tubular transfer rates (Tm) of both p-aminohippurate (PAH) and diodrast (3,5-diiodo-4-pyridone-N-acetic acid or iodopyracet) were found to be fixed and reproducible when measured separately in Lophius (goosefish) under standard laboratory conditions. Expressed on a molar basis TmPAH was four times TmD. However, when these transport competitors were presented simultaneously in equimolar concentrations with the plasma levels of each sufficiently high enough to saturate the carrier system, the relative rates of excretion were reversed with the diodrast transfer rate then four times that of PAH. The combined rate of excretion was far below TmPAH alone, and roughly equal to TmD. Interaction with a common carrier was indicated by the gradations in degree of inhibition which resulted when plasma concentration ratios of diodrast to PAH were extended from 0.1 to 3.2, and PAH transfer rates expressed as percentage of TmPAH were correspondingly depressed from 17 to 1.0 per cent respectively. These observations again point up the inverse relationship between transfer rate and competitive effectiveness which exists for members of a series of substances actively transported by a common mechanism. It appears that carrier affinity and dissociation characteristics may be quite different for various compounds in a series, and also that these parameters may vary significantly from species to species.
Spontaneous Activity in Crustacean Neurons
Authors: Preston James B. , Kennedy Donald
Published: May 2004

Single units which discharged with regular spontaneous rhythms without intentional stimulation were observed in the ventral nerve cord by intracellular recording close to the sixth abdominal ganglion. These units were divided into two groups: group A units in which interspike intervals varied less than 10 msec.; group B units in which interspike intervals varied within a range of 10 to 30 msec. Group A units maintained "constant" interspike intervals and could not be discharged by sensory inputs, while the majority of group B units could be discharged by appropriate sensory nerve stimulation. Both group A and B units discharged to direct stimulation when the stimulating and recording electrodes were placed in the same ganglionic intersegment, and directly evoked single spikes reset the spontaneous rhythm. In group B units, presynaptic volleys reset the spontaneous rhythm of some units; but in others, synaptically evoked spikes were interpolated within the spontaneous rhythm without resetting. The phenomenon of enhancement could also be demonstrated in spontaneously active units as a result of repetitive stimulation. It is concluded that endogenous pacemaker activity is responsible for much of the regular spontaneous firing observed in crayfish central neurons, and that interaction of evoked responses with such pacemaker sites can produce a variety of effects dependent upon the anatomical relationships between pacemaker and synaptic regions.
Studies on the Effects of Gaseous Ions on Plant Growth
Authors: Krueger Albert P. , Kotaka Sadao , Andriese Paul C. ,   with the technical assistance of Eddie J. Reed.
Published: May 2004

Exposure of Avena sativa seedlings to unipolar ionized atmospheres of either charge produced statistically significant stimulation of growth as measured by mean stem length, integral elongation, and dry weight. The extent of growth increase was related to the atmospheric ion density and this in turn determined the magnitude of current flow to ground. The minimal current measured in the ground circuit and capable of producing a measurable difference in growth was 4.3 to 4.6 x 10-13 amp/plant.
Studies on the Movement of Water through the Isolated Toad Bladder and Its Modification by Vasopressin
Authors: Hays Richard M. , Leaf Alexander
Published: May 2004

Measurements of diffusion permeability and of net transfer of water have been made across the isolated urinary bladder of the toad, Bufo marinus, and the effects thereon of mammalian neurohypophyseal hormone have been examined. In the absence of a transmembrane osmotic gradient, vasopressin increases the unidirectional flux of water from a mean of 340 to a mean of 570 µl per cm2 per hour but the net water movement remains essentially zero. In the presence of an osmotic gradient but without hormone net transfer of water remains very small. On addition of hormone large net fluxes of water occur; the magnitude of which is linearly proportional to the osmotic gradient. The action of the hormone on movement of water is not dependent on the presence of sodium or on active transport of sodium. Comparison of the net transport of water and of unidirectional diffusion permeability of the membrane to water indicates that non-diffusional transport must predominate as the means by which net movement occurs in the presence of an osmotic gradient. An action of the hormone on the mucosal surface of the bladder wall is demonstrated. The effects of the hormone on water movement are most simply explained as an action to increase the permeability and porosity of the mucosal surface of the membrane.
Phospholipid-Cholesterol Membrane Model
Authors: Tobias Julian M. , Agin Daniel P. , Pawlowski Raymond
Published: May 2004

A cephalin-cholesterol membrane model is described whose electrical resistance can be reversibly raised by CaCl2 or lowered by KCl or NaCl whether these ions are added to the membrane by mechanical immersion or are driven in electrically. Either KCl or NaCl acts antagonistically to CaCl2. Experiments with controlled pH indicate that the above effects depend somehow on combination of the cations with the phospholipid acidic groups. Also, they are correlated with decreased membrane hydration in CaCl2 solutions, and increased hydration in KCl or NaCl solutions. It is conjectured that cells may regulate their transsurface ion pathways and fluxes by K-Ca competition for negatively charged binding sites on plasma membrane phospholipid. It is regarded as a corollary to say that a fundamental event in excitation is displacement of membrane Ca from such a site by catelectrotonically propelled K.
Effect of High Oxygen Tension on Potassium Retentivity and Colony Formation of Bakers' Yeast
Authors: Stuart B. , Gerschman R. , Stannard J. N.
Published: May 2004

The ability of yeast cells to retain potassium and to form colonies was studied after exposure to pressures ranging from 2 to 143 atmospheres of oxygen. The investigations allow comparison of these responses with those found after x-ray exposure. Exposure to 2 to 8 atmospheres of oxygen for 2, 20, and 40 hours showed decreased potassium leakage as measured by an elution technique. Further experiments using 0.5 to 22 hour exposures to 10 to 143 atmospheres of oxygen showed decreased potassium leakage when glucose was present in the test media, but increased leakage (as did x-ray effects) in the absence of substrate. There was increased potassium leakage into the suspending media (distilled water) during oxygen exposure but this usually did not affect the leakage rates measured subsequently. Marked inability to form colonies was observed after 20 hour exposures to 100 atmospheres of oxygen, with a much smaller response at lower pressures. Increased oxygen concentrations, not pressure, evidently caused these effects, since comparable pressures of nitrogen produced almost no change. The ratio of potassium leakage to survival sensitivity was found to be approximately unity when comparing exposures causing 50 per cent damage. This is quite different from that seen with x-ray or ultraviolet irradiation.
The Effect of Insulin on the Distribution of Glucose between the Blood Plasma and the Liver
Authors: Hetenyi G. , Arbus G. S. ,   with the technical assistance of W. G. Layng.
Published: May 2004

In normal fasted rats whole liver tissue contains as much glucose as the blood plasma, i.e., the ratio of the concentrations is about unity. The concentration of glucose in hepatic intracellular water is about 1.2 times higher than in plasma water. In rats injected with insulin the concentration of glucose in the liver falls to a lesser extent than in the plasma: resulting in a ratio of concentrations higher than unity. If insulin hypoglycemia is prevented by the ingestion of glucose the concentration ratio is less than in hypoglycemic rats but still significantly above unity. In normal rats the specific activities of plasma and hepatic glucose do not differ significantly at 7.5, 15, and 30 minutes after the intravenous injection of C14-labeled glucose. In rats injected with insulin the specific activity of glucose is higher in the plasma than in the liver at 7.5 and 15 minutes, but not at 30 minutes following the injection of tracer. In insulin-treated hypoglycemic rats considerably higher concentrations of labeled glucose are found in hepatic intracellular than in plasma water. The penetration of C14-glucose from plasma into hepatic intracellular water is found to be fast. Excess insulin causes an accumulation of glucose within the liver cells by retaining newly formed glucose and by the taking up of glucose from the plasma against an existing concentration gradient.
Qualitative Behavior of Spontaneous Potentials from Explants of 15 Day Chick Embryo Telencephalon in Vitro
Authors: Cunningham A. W. B.
Published: May 2004

The apparatus and technique used in the preparation and observation of explants of brain tissue capable of producing spontaneous potentials in vitro are described. The magnitude and pattern of spontaneous potentials from explants of telencephalon of 15 day chick embryos (measured using external bare platinum electrodes) and some aspects of their "normal" behavior during 12 days in vitro are also described. No change was noted in these potentials with change of amplifiers, recorders, or electrodes. The response of the potentials to change in temperature and proportionate composition of the atmosphere around the explant was such as to suggest that the potentials arise as a result of a living process. The changes brought about by the administration of anesthetics, strychnine, brucine, and barbiturates were those that might be anticipated in a normal functional activity of the central nervous system. It is concluded that these potentials are a true physiological phenomenon and arise from living cells of the central nervous system.
Identification of Active Membrane Areas in the Giant Neuron of Aplysia
Authors: Tauc L.
Published: May 2004

Intracellular and extracellular potentials were simultaneously recorded from the soma and different parts of the axon of the giant cell of Aplysia. Evidence was obtained that for all modes of stimulation the spike originates in the axon at some distance from the cell body. The conduction of the spike is blocked at a distance of 200 to 300 µ from the soma for the antidromic spike, closer to the soma for an orthodromic spike. This event is recorded in the soma as a small or A spike. After some delay, a spike is initiated in the resting part of the axon and in the axon hillock; the soma is invaded only afterwards. The response of these three parts of the neuron is recorded in the soma as the big or S spike.
Electrical Changes in Pre- and Postsynaptic Axons of the Giant Synapse of Loligo
Authors: Takeuchi Akira , Takeuchi Noriko
Published: May 2004

Potential changes both in pre- and postsynaptic axons were recorded from the giant synapse of squid with intracellular electrodes. Synaptic current was also recorded by a voltage clamp method. Facilitation of postsynaptic potential caused by applying two stimuli several milliseconds apart was accompanied by an increase in the amplitude of the presynaptic action potential. Depression of the postsynaptic potential occurred without changes in the presynaptic action potential. Increase in the concentration of Ca in sea water caused an increase in amplitude of the synaptic current. On the other hand increase in Mg concentration decreased the amplitude of the synaptic current. In these cases no appreciable change in the presynaptic action potential was observed. Extracellularly recorded potential changes of the presynaptic axon showed mainly a positive deflexion at the synaptic region and a negative deflexion in the more proximal part of the presynaptic axon. Mechanism of synaptic transmission is discussed.
Action of Antidiuretic Hormone on the Equivalent Pore Radius at both Surfaces of the Epithelium of the Isolated Toad Skin
Authors: Whittembury Guillermo
Published: May 2004

A previously described method (1) allows the observation of swelling and shrinking of the epithelial cells of the isolated toad skin, when the solution bathing either the outer or inner side of the skin is modified. Thus, the concentration of probing molecules of graded size, isotonic to the epithelial cells, across each face of the isolated toad skin can be determined. These concentrations have been used for the estimation of the equivalent pore radius at the outer and inner face of the skin epithelium, following the approach of Goldstein and Solomon for red cells (3). An equivalent pore radius of 4.5 A for the outer surface, and one of 7 A for the inner surface have been obtained. Antidiuretic hormone had an effect only when added to the inner side. This effect was only at the outer surface and is interpreted as widening of the 4.5 A pores to about 6.5 A. A model membrane, formed by narrow and wide pores in series, may explain some of the apparent inconsistencies previously observed.
Cation Transport in Escherichia coli
Authors: Schultz Stanley G. , Wilson Norman L. , Epstein Wolfgang
Published: May 2004

The intracellular Cl concentration in E. coli has been studied as a function of the Cl concentration in the growth medium and the age of the bacterial culture. The ratio of extracellular to intracellular Cl concentration is shown to be 3.0 in the logarithmic phase and 1.13 in the stationary phase, both ratios being independent of the extracellular Cl concentration. If it may be assumed that Cl is passively distributed in this organism, these results are consistent with a transmembrane P.D. of 29 mv, interior negative, during the logarithmic phase, and 3 mv, interior negative, in the stationary phase.
Potassium and the Recovery of Arterial Smooth Muscle after Cold Storage
Authors: Barr Lloyd , Headings Verle E. , Bohr David F.
Published: May 2004

The influence of K on the performance of vascular smooth muscle was studied by observing the mechanical performance of the muscle under conditions in which the magnitudes of [Ki] and of the [Ki]:[Ko] ratio varied in opposite directions. During prolonged storage at 4°C the artery strips lost K and their ability to respond to stimuli. Subsequently they were transferred to recovery solutions of various [Ko] at 38°C. The initial rate of Ki reaccumulation and steady state [Ki] were greater in solutions of higher [Ko]. Conversely for any time during recovery, the greater [Ko], the smaller the [Ki]:[Ko] ratio. When the strip was placed in the warm recovery solution it first contracted and then relaxed. The initial contraction was not relatable to [Ko] of the recovery solution but the subsequent relaxation was greater in rate and magnitude as [Ko] was greater. As the muscles recovered further they went into tonic contracture. As the [Ko] in the recovery solutions was greater these contractures occurred after shorter recovery times, and attained greater amplitude at a faster rate. Solution-switching experiments indicated a dependence of responses to electrical shocks on both the [Ki]:[Ko] ratio and [Ki]. Conclusions drawn were: (a) increased [Ki] increases contractility, (b) increased [Ki] increases the rate of relaxation, (c) excitability is decreased by too high or low a [Ki]: [Ko] ratio, and (d) the extent of tonic shortening depends on the [Ki]:[Ko] ratio.
Contraction and Action Potentials of Frog Heart Muscles Soaked in Sucrose Solution
Authors: Van der Kloot William G. , Rubin Nira S.
Published: May 2004

Isolated auricles or ventricles from the frog continue to contract, either spontaneously or when stimulated, for from 2 to 4 hours after they are placed in isotonic sucrose solution. After the muscles stop contracting in sucrose solution, contractility is partially restored when the muscles are placed in chloride Ringer's. However, contractility is usually not restored if the muscles are placed in sulfate Ringer's. Ventricles soaked in sucrose solution at 4–7°C continue to contract for 12 to 24 hours and during the first few hours in sucrose solution the contractions often are enhanced. Several types of experiment indicate that the sucrose solution does replace the Ringer's in the extracellular space. Auricles and ventricles also continue to conduct action potentials, with an overshoot, for from 30 to 360 minutes after being placed in sucrose solution. Muscles soaked in sucrose until they are inexcitable rapidly recover in chloride Ringer's but often fail to recover in sulfate Ringer's. The results are discussed in relation to theories about the generation of the action potential in cardiac muscle, and the role of the extracellular fluid in contraction.
Delayed Rectification and Anomalous Rectification in Frog's Skeletal Muscle Membrane
Authors: Nakajima Shigehiro , Iwasaki Shizuko , Obata Kunihiko
Published: May 2004

Delayed rectification was elicited in frog's skeletal muscles bathed in choline-Ringer's solution, in normal Ringer's solution with tetrodotoxin, in 40 mM Na2SO4 solution with tetrodotoxin, and even in 40 mM K2SO4 solution when the membrane had been previously hyperpolarized. However, after a sustained depolarization current-voltage relations in 40 mM K2SO4 and in 40 mM Na2SO4 solutions revealed a rectifier property in the anomalous direction. This indicates that the increase in potassium conductance which is brought about upon depolarization is a transient phenomenon and is inactivated by a maintained depolarization, and that this potassium inactivation process converts the delayed rectification into the anomalous rectification. In normal Ringer's solution with tetrodotoxin and in the 40 mM Na2SO4 solution with tetrodotoxin the apparent resistance was increased when the membrane was hyperpolarized beyond about -150 mv. This is thought to be due to a decrease of K conductance caused by a strong hyperpolarizing current. In the 40 mM Na2SO4 solution with tetrodotoxin a de- or hyperpolarizing current pulse induced a prolonged depolarizing response. During the early phase of this response the effective resistance was lower, and during the following phase greater than that in the resting fiber. An interpretation in terms of the ionic hypothesis was made of the nature of this response.
Comparison of Stimulus Energies Required to Elicit the ERG in Response to X-Rays and to Light
Authors: Bachofer C. S. , Wittry S. Esperance
Published: May 2004

The retina of Rana pipiens, the leopard frog or grass frog, is shown to be an extremely sensitive detector of x-rays. Its sensitivity to x-rays equals in some respects its sensitivity to visible light. The energy required for the response to visible light is so low that the reaction has long been known as one of the most sensitive in biological systems. An exact comparison is made of the amount of energy required in the stimulus to elicit an electroretinogram (ERG) in response to x-rays and in response to light. ERG's from threshold responses to maximal responses obtainable with x-rays and with light are reproduced. The rods of the retina are shown to be responsible for the production of the ERG. The actual amount of energy absorbed in the rhodopsin from x-ray and from light stimulation over a wide range of intensities and durations has been determined and has been related to the amplitude of the ERG. To the question whether light or x-rays are more efficient in eliciting an ERG, no simple or unequivocal answer can be given. The three dimensional relationship of amplitude of response, intensity of stimulus, and duration of stimulus shows rather unexpectedly that in certain regions light is more efficient while in other regions x-rays are more efficient.
Fluorescence Changes in Nerve Induced by Stimulation
Authors: Ungar Georges , Romano Dominick V.
Published: May 2004

It was previously assumed, on the basis of changes in the ultraviolet absorption spectrum and of increase in ionizable sulfhydryl groups, that during excitation the proteins of excitable structures undergo some structural rearrangements, and these rearrangements may be similar to those designated by the term transconformation. In the present experiments, it was observed that electrical stimulation of peripheral nerves from rat, guinea pig, frog, and crab causes a decrease in their fluorescence. The peaks of the emission and activation spectra correspond to those attributed to proteins. Denaturing agents, such as urea, were also found to decrease the fluorescence of nerve extracts. It is, therefore, probable that the decrease in fluorescence, associated with the excited state, is due to a change in the configuration of the nerve proteins. The fluorescent method is applicable not only to tissue extracts but allows the observation of surviving nerve fibers before, during, and after stimulation. It showed that fluorescence of the fibers decreases invariably during stimulation and tends to return to the control level during restoration. The reduction in fluorescence is quantitatively related to the number of stimuli received by the nerve.