bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE EFFECT OF SPECIFIC POISONS UPON THE PHOTO-REDUCTION WITH HYDROGEN IN GREEN ALGAE
Authors: Gaffron Hans 
Published: May 2004

1. The effect of poisons upon the photoreduction with hydrogen in Scenedesmus and similar algae has been studied. The poisons used were cyanide, hydroxylamine, dinitrophenol, and carbon monoxide, substances known to inhibit more or less specifically certain enzymatic reactions.
2. It was found that quite generally one has to distinguish between the action of poisons upon the photoreduction in the stationary state, once this type of metabolism has been well established in the cells, and their effects on transition phenomena, on the "adaptation" and its reversal, the "turnback" from photoreduction to photosynthesis.
3. Cyanide inhibits photoreduction more strongly than it inhibits photosynthesis in the same algae. It is concluded that the mechanism of oxygen liberation, which is idle in photoreduction, is not very sensitive to cyanide.
4. Hydroxylamine in low concentrations is a powerful inhibitor of photosynthesis but has practically no influence on the rate of photoreduction. Consequently, it is assumed that it acts in photosynthesis mainly by inhibiting the evolution of oxygen. Greater concentrations of hydroxylamine clearly inhibit photoreduction, but diminish the rate to about one-half only. A greater degree of inhibition is obtained only by prolonged incubation.
5. Dinitrophenol was found to inhibit strongly the reduction of carbon dioxide, under aerobic as well as under anaerobic conditions. A stimulating effect of dinitrophenol can be demonstrated only with respiration or fermentation, not with photosynthesis.
6. Carbon monoxide interferes with all phases of the hydrogen metabolism in algae. It is supposed therefore to be a specific inhibitor for the hydrogenase system.
7. The "adaptation" to the hydrogen metabolism, which takes place if the algae are incubated anaerobically in hydrogen for several hours, is inhibited completely by very small amounts of cyanide. The adaptation reaction is more sensitive to cyanide than most of the other metabolic processes in the same cell. Correspondingly cyanide enhances the return to aerobic conditions, the "turnback," which occurs under the influence of light of high intensities.
8. Hydroxylamine, applied aerobically, inhibits the adaptation reaction to about the same degree as it inhibits photosynthesis. Photoreduction proceeds after the adaptation in presence of hydroxylamine only at a fraction of the rate that it would have if the poison were added later.
9. Hydroxylamine in concentrations of 10–3 M protects the anaerobic metabolism against the return to aerobic photosynthesis which normally occurs under the influence of light of too high intensity. The protection is only relative and the higher the light intensity the more hydroxylamine is needed to keep photoreduction going. Once a "turnback" occurs in presence of much hydroxylamine all photochemical gas exchange comes to an end.
ACTION OF INHIBITORS ON HYDROGENASE IN AZOTOBACTER
Authors: Wilson J. B. , Wilson P. W. 
Published: May 2004

The inhibitors usually associated with the activity of the cytochrome oxidase system—cyanide and carbon monoxide—are also effective in reducing the oxidation of H2 by intact cells of Azotobacter vinelandii. The hydrogenase system is more sensitive to CO than is the respiratory system.
Oxidation of a carbon source and of hydrogen by Azotobacter cells is inhibited in a quantitatively different manner by the following compounds: sodium azide, hydroxylamine, sodium iodoacetate, and sodium fluoride. In every case, a concentration range which is definitely inhibitory for respiration has little or no effect on the hydrogenase activity.
The differential inhibition by hydroxylamine explains certain observations in the literature which have been erroneously interpreted as demonstrating a specific inhibition by NH2OH of biological nitrogen fixation. This supposed demonstration has been offered as support for the hypothesis that NH2OH is an intermediate in the fixation reaction.
The differential inhibitors can be used for detection of hydrogenase in cultures possessing a high endogenous respiration. The method is illustrated by an experiment with root nodule bacteria from pea and cowpea nodules. No hydrogenase was found in either.
THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR
Authors: Sollner Karl , Carr Charles W. 
Published: May 2004

1. Experiments were carried out to decide whether or not the electromotive properties of dried collodion membranes depend upon their thickness.
2. A number of dried collodion membranes of varying thickness, 3–160 µ, were prepared from collodion preparations of different electrochemical activity. The characteristic concentration potentials across them were measured and the means of these values determined for each thickness.
3. The characteristic concentration potentials across dried collodion membranes are a function of their thickness. The thinnest membranes yield in all cases the lowest concentration potentials; increasingly thicker membranes give increasingly higher potential values, until a constant value is reached which is characteristic of the particular collodion preparation used. With electrochemically active collodion, characteristic concentration potentials approaching the thermodynamically possible maximum are obtained with membranes of only 10 µ thickness, thinner membranes giving appreciably lower values. With two rather inactive commercial collodion preparations the characteristic concentration potential increases from about 30 mv. for membranes 3 µ thick to about 42 mv. for 20 µ membranes; still thicker membranes do not show a significant increase in the potential values. With a highly purified collodion preparation the constant maximum value was found to be about 32 mv., 4 µ thick membranes giving only about 22 mv.
4. These results do not support the homogeneous phase theory as applied to the dried collodion membrane. They are readily compatible with the micellar-structural theory. Several special possible cases of the latter as applied to the dried collodion membrane are discussed.
THE TURNOVER RATE OF PHOSPHOLIPIDS IN THE PLASMA OF THE DOG AS MEASURED WITH RADIOACTIVE PHOSPHORUS
Authors: Zilversmit D. B. , Entenman C. , Fishler M. C. , Chaikoff I. L. 
Published: May 2004

1. A method for the determination of turnover time and turnover rate of plasma phospholipid is presented.
2. During the postabsorptive state 5.2 to 8.0 mg. of phospholipid phosphorus are turned over per hour in the plasma of dogs weighing 6–9 kilos.
3. The amount of phospholipid in an organ that is supplied by plasma phospholipid per hour is calculated.
STUDIES ON THE MECHANISM OF HYDROGEN TRANSPORT IN ANIMAL TISSUES
Authors: Potter V. R. , DuBois K. P. 
Published: May 2004

1. The mechanism of succinic dehydrogenase action was studied by means of inhibitors.
2. The enzyme is inhibited by a large number of diverse compounds whose only common denominator appears to be their ability to react with SH groups. These compounds include quinonoid structures, sulfhydryl reagents, sulfhydryl compounds, copper, zinc, selenite, and arsenite.
3. In contrast to the above inhibitors, the action of malonate does not appear to involve sulfhydryl groups and is explained on the basis of its affinity for the enzyme groups which react with the carboxyl groups of succinate.
4. The action of malonate and the sulfhydryl reactants is mutually exclusive, and this fact suggests the conclusion that the sulfhydryl group of the enzyme is located between the carboxyl affinity points.
5. On the basis of the deduced structure of the succinate-activating center of the enzyme, it is suggested that the enzyme may function by oscillating between the EnSH and EnS· forms, rather than by a thiol-disulfide equilibrium.
PACEMAKERS IN NITELLA
Authors: Osterhout W. J. V. 
Published: May 2004

An electrical impulse traveling along a Nitella cell may produce a complete or a partial response. The two kinds of response may occur in regular alternation.
The partial response varies greatly and may be so far reduced as to appear as a local thickening in the upstroke of the action curve, usually accompanied by a more or less pronounced hump. In consequence a considerable variety of action curves is produced.
The observations show that different regions of the cell may react differently.
NATIVE AND REGENERATED BOVINE ALBUMIN
Authors: Martin Donald S. , Erickson John O. , Putnam Frank W. , Neurath Hans 
Published: May 2004

1. The effects of regeneration of whole bovine albumin on antigenic activity and serological specificity were determined by precipitin measurements on rabbit antisera to (1) native whole albumin, (2) albumin regenerated from 8 M urea, and (3) albumin regenerated from 8 M guanidine hydrochloride.
2. While numerically the mean antibody response to these three antigens was found to decrease in the order named, only the difference in antigenic activity between native and guanidine hydrochloride-regenerated albumin was statistically significant. Native, crystalline, carbohydrate-free albumin (crystalbumin) was considerably less antigenic than native whole bovine albumin, its activity being comparable to, if not less than, that observed for guanidine hydrochloride-regenerated whole albumin.
3. All four antigens were immunologically equivalent.
4. The antigenic activity of these proteins is discussed in terms of protein structure and carbohydrate content.
THEORY AND MEASUREMENT OF VISUAL MECHANISMS
Authors: Crozier W. J. , Wolf Ernst 
Published: May 2004

Flicker response contours (F vs. log Im) for a square image subtending 0.602° on a side, located in the fovea, are simplex probability integrals for a "white" and for four (five) spectral regions filtered from this white, and with different light-time fractions in the flash cycle. The subjective phenomena (the appearance of the field, the intensity threshold for color, and others) at the fusion points along these contours parallel in a variety of ways those obtained on duplex flicker contours resulting from the use of larger or eccentrically placed flickered images. These phenomena therefore cannot be held to indicate involvements of "rod" excitation.
The scatter of the index of variation of I1 is such as to demonstrate the full participation of all the potentially excitable neural units at all levels of flash frequency, for each kind of light. The magnitude of this scatter, a measure of neural integration in visual performance, is a function of the number of these units (with Fmax. nearly constant); the two quantities vary together when wave-length composition of light is altered.
The properties of the contours for a white light and for the spectral regions filtered from it show that, for the image within the fovea, different numbers of units are excitable in flicker recognition according to the wave-length band used, and different mean frequencies of elements of effect under fixed conditions. The changes in the mean intensity for activation of these units as a function of the light-time fraction in the flash cycle are correlated with the numbers of these units; when this is corrected for, it is pointed out that despite the differences in shape of F vs. log I it cannot be concluded that the mechanism of excitation differs for different wave-lengths. It is indicated that "white" must be regarded as a synthesis, not a mere summation, of effects due to different spectral regions. Certain differences are pointed to as between foveal and more peripheral regions tested, and as between observers differing in the degree of the "yellow spot effect," with regard to the relative effects of wave-length and of image area. A general consequence is the outlining of conditions required for the precise comparison of excitabilities as a function of wave-length in the multivariate visual system.
STUDIES ON THE ANOMALOUS VISCOSITY AND FLOW-BIREFRINGENCE OF PROTEIN SOLUTIONS
Authors: Lawrence A. S. C. , Needham Joseph , Shen Shih-Chang 
Published: May 2004

1. A coaxial viscosimeter which permits the simultaneous determination of relative and anomalous viscosity and of flow-birefringence is described. Flow-anomaly and flow-birefringence are regarded as characteristic of elongated micelles and molecules.
2. Such methods have been applied to dilute solutions of proteins. The conditions under which the coaxial (Couette) viscosimeter measures the viscosity of the bulk phase and the surface film phase respectively have been investigated and are described.
3. The general behaviour of protein solutions subjected to shear is summarised.
STUDIES ON THE ANOMALOUS VISCOSITY AND FLOW-BIREFRINGENCE OF PROTEIN SOLUTIONS
Authors: Lawrence A. S. C. , Miall Margaret , Needham Joseph , Shen Shih-Chang 
Published: May 2004

1. An extensive investigation has been made of protein particle shape using the methods of flow-birefringence and anomalous viscosity measurement in the coaxial cell.
2. As a result of investigations on a number of proteins, it is concluded that they may be divided into four groups.
Group A consists of those which show flow-anomaly both in the bulk phase and in the surface film. These also show flow-birefringence in the bulk phase. Examples: tobacco mosaic disease virus nucleoprotein; myosin. Though corpuscular proteins, they have elongated particles before denaturation.
Group B consists of those which show flow-anomaly only (in the first instance) in the surface film, and no flow-birefringence in the bulk phase. They are probably close to spherical in shape in solution, but form elongated particles as they denature in the surface film. After this process has been completed, they may show flow-anomaly also in the bulk phase. Some proteins show flow-anomaly in the surface film immediately it forms, others only show it after a certain time has elapsed for the building up of the film. We designate the former as group B1 and the latter as group B2.
Group B1, immediate surface film flow-anomaly. Examples: serum euglobulin, amphibian embryo euglobulin b.
Group B2, slowly appearing surface film flow-anomaly. After the film has once been fully formed and then dispersed by shaking, the solution may have the properties of that of a protein in group B1; i.e., anomalous flow in the film may occur immediately on testing in the viscosimeter. Examples: avian ovalbumin, amphibian embryo pseudoglobulin.
Group C consists of those proteins which show flow-anomaly neither in the bulk phase nor in the surface film, under the conditions used by us. They are probably close to spherical in shape. Examples: insulin, methaemoglobin, amphibian embryo euglobulin c, mucoproteins.
3. The theoretical significance of protein fibre molecules, whether native or formed by denaturation in the living cell, is discussed, especially in relation to experimental morphology and cytology.
THE EFFECT OF CARBON DIOXIDE TENSION ON THE METABOLISM OF CEREBRAL CORTEX AND MEDULLA OBLONGATA
Authors: Craig Francis N. 
Published: May 2004

Manometric measurements were made of oxygen uptake (QOO2) and aerobic lactic acid output (QG) by slices of cerebral cortex and medulla oblongata of the cat in the presence of mixtures of 1, 5, and 20 volumes per cent of carbon dioxide in oxygen. The concentrations of NaHCO3 and NaCl in the medium were varied to maintain constant pH and sodium ion concentrations. The calcium ion concentration was 0.0002 M.
At pH 7.5 under these conditions, an increase in carbon dioxide from 1 per cent to 5 per cent doubled the QG of both tissues but did not alter QOO2; an increase from 5 per cent to 20 per cent carbon dioxide had no further effect on QG in either tissue or QOO2 of cortex, but did depress the QOO2 of medulla.
At pH 8.1, an increase in carbon dioxide from 1 per cent to 5 per cent raised the QOO2 and QG of cortex by about 60 per cent.
Measurements at low oxygen tension carried out previously in phosphate medium were repeated in bicarbonate medium to obtain data for the combined output of lactic acid and carbon dioxide (QA). When the oxygen in the gas phase was decreased from 95 to 3 volumes per cent, the lactic acid output as measured colorimetrically increased by 114 mg./gm. in cortex and by 8 mg./gm. in medulla; QA increased from 12.3 to 13.5 in cortex and decreased from 5.1 to 3.8 in medulla.
DIFFERING RATES OF DEATH AT INNER AND OUTER SURFACES OF THE PROTOPLASM
Authors: Osterhout W. J. V. 
Published: May 2004

When protoplasm dies it becomes completely and irreversibly permeable and this may be used as a criterion of death. On this basis we may say that when 0.2 M formaldehyde plus 0.001 M NaCl is applied to Nitella death arrives sooner at the inner protoplasmic surface than at the outer.
If, however, we apply 0.17 M formaldehyde plus 0.01 M KCl death arrives sooner at the outer protoplasmic surface.
The difference appears to be due largely to the conditions at the two surfaces. With 0.2 M formaldehyde plus 0.001 M NaCl the inner surface is subject to a greater electrical pressure than the outer and is in contact with a higher concentration of KCl. In the other case these conditions are more nearly equal so that the layer first reached by the reagent is the first to become permeable.
The outer protoplasmic surface has the ability to distinguish electrically between K+ and Na+ (potassium effect). Under the influence of formaldehyde this ability is lost. This is chiefly due to a falling off in the partition coefficient of KCl in the outer protoplasmic surface.
At about the same time the inner protoplasmic surface becomes completely permeable. But the outer protoplasmic surface retains its ability to distinguish electrically between different concentrations of the same salt, showing that it has not become completely permeable.
After the potential has disappeared the turgidity (hydrostatic pressure inside the cell) persists for some time, probably because the outer protoplasmic surface has not become completely permeable.
THE PENETRATION OF AMMONIA INTO FROG MUSCLE
Authors: Fenn Wallace O. , Haege Lorraine F. , Sheridan Eugenia , Flick John B. 
Published: May 2004

1. A study was made of the electrolyte changes which occur when frog muscles are immersed in a Ringer solution with 1/5 of the Na replaced by NH4Cl. Analyses were made in the solution and in the muscles for K and NH3, and the muscles were also analyzed for Cl, HCO3, and Na. Control muscles were immersed in normal Ringer's solution and similarly analyzed.
2. The amount of ammonia taken up was about equal to the K and Na lost. There was also a small increase in chloride content. The bicarbonate content was the same in both experimental and control muscles, indicating no change in the muscle pH due to the NH3 which penetrated. An increased loss of K due to the penetration of NH3 was also demonstrated by the use of radioactive K.
3. After 5 hours, the concentration of ammonia per gram of muscle is about the same as the concentration in the solution. After 4 or 5 days, the concentration in the muscle is about 1.5 times that in the solution. The inside to outside NH3 ratio is about equal to the corresponding H ion ratio, but is much less than the K ratio.
4. The rate of penetration of the NH3 is increased by a rise of temperature, by stirring the solution, and by decrease in the concentration of Na, K, Ca, or Mg in the solution; it is decreased by increasing the size of the muscles or by killing them with chloroform or boiling.
5. Liver, smooth muscle, skin, and kidney, in a few experiments, behaved much like muscle except that there was a formation of urea in the case of liver.
6. The injection of NH4Cl into anesthetized cats causes an increase in the level of K in the blood plasma.
THE RHEOLOGY OF THE BLOOD. III
Authors: Bingham Eugene C. , Roepke Raymond R. 
Published: May 2004

The authors have confirmed the fact that blood serum and plasma behave rheologically like a true viscous liquid. It is true for whole blood only to a first approximation, but with this reservation they have studied the available data and extended the equation of Bingham and Durham to cover protein solutions of various concentrations and at various temperatures as well as mixtures of proteins and corpuscles present in whole blood. If Φ is the fluidity of whole blood, Φ1 is the fluidity of water and ΔΦ = Φ – Φ1, then
ΔΦ = ß1b1 + ß2b2 + ß3b3 + ···
where ß1, ß2, ß3, etc., are constants for the fluidity lowering of the salts, albumin, globulin, fibrinogen, and the corpuscles, etc., present in the whole blood.
The conclusions from the data referred to are intended to buttress this simple equation (6).
CULTURE CONDITIONS AND THE DEVELOPMENT OF THE PHOTOSYNTHETIC MECHANISM
Authors: Myers Jack , Clark L. B. 
Published: May 2004

1. An apparatus has been developed which maintains a constant density of population of Chlorella by automatic dilution of the growing culture with fresh medium.
2. Cells harvested from the apparatus in daily samples are highly uniform in rate of growth and rate of photosynthesis measured under arbitrarily chosen conditions.
THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR
Authors: Carr Charles W. , Gregor Harry P. , Sollner Karl 
Published: May 2004

The technique of Abrams and Sollner for the preparation of electropositive dried protamine collodion membranes has been improved. Porous collodion membranes cast on the outside of rotating tubes are treated for 48 hours with a solution of 2 per cent protamine sulfate buffered at pH 11. After being washed thoroughly the membranes are dried in air for several hours, soaked in water for several hours, and removed from the tubes. Further drying in air but without support shrinks the membranes slightly. The resulting membranes are designated "permselective" or "megapermselective" protamine collodion membranes. These membranes regularly give characteristic concentration potentials of –52 to –53 mv. and (in 0.1 M KCl) resistance of 0.5 to 15 ohms per membrane of 50 cm.2 area. This resistance is several orders of magnitude smaller than that of the conventional dyestuff- and alkaloid-impregnated positive membranes. The megapermselective protamine collodion membranes can be kept either dry or in water for prolonged periods without detectable deterioration. They are quite smooth, have a regular shape, and stand considerable handling without breakage.
The megapermselective protamine collodion membranes are the electropositive analogues of the electronegative megapermselective collodion membranes described by Carr and Sollner.
ELECTRIC TISSUE
Authors: Cox R. T. , Coates C. W. , Brown M. Vertner 
Published: May 2004

In the main electric organs of the electric eel, the cross-sectional area, the thickness of the electroplaxes, and certain electrical characteristics of the tissue vary widely between the anterior and posterior ends. However, a transverse layer of the organs one electroplax thick has certain characteristics which are roughly uniform along the organs. These are its volume, its maximum voltage, its maximum current per unit area, and the resistance of unit area at the peak of the discharge.
Measurements of the voltage developed by a segment of the organs across different external resistances at different instants during the discharge are all rather well described by representing the segment, with the adjacent non-electric tissue, as a simple combination of E.M.F. and ohmic resistance. The internal resistance of the tissue varies during the discharge. Its E.M.F. appears to be practically constant, at least during the greater part of the discharge.
Estimates made of the total electric energy show it about equal to the energy supplied by the decrease of phosphocreatine and the formation of lactic acid.