bluuebunny/crossref_metadata_2025_split huggingface dataset:
STUDIES ON THE MECHANISM OF ACETATE OXIDATION BY BACTERIA
Authors: Ajl Samuel J. 
Published: May 2004

1. Simultaneous oxidation of C14-methyl-labeled acetate, and unlabeled malate or fumarate and α-ketoglutarate results in entrapment of labeled carbon in the C4-dicarboxylic acids, but not in α-ketoglutarate, although all substrates are utilized at comparable rates.
2. A large endogenous reduction of all C4-dicarboxylic acids (fumarate, oxalacetate, and malate) to succinate is observed under aerobic conditions, and when vigorous oxidation is proceeding. This effect occurs with both freshly harvested young (18 hour) cells and stored (2 week) cells.
3. This reduction can be considerably minimized under high oxygen tensions.
4. The quantitative concordance of these results with a Thunberg-Knoop cyclic mechanism for acetate oxidation is shown. Possible alternative C4 products formed prior to succinate are not completely excluded, but it appears that the cells can utilize the succinate condensation as a major pathway in acetate oxidation.
LIGHT PRODUCTION BY GREEN PLANTS
Authors: Strehler Bernard L. , Arnold William 
Published: May 2004

1. Green plants have been found to emit light of approximately the same color as their fluorescent light for several minutes following illumination. This light is about 10–3 the intensity of the fluorescent light, about one-tenth second after illumination below saturation or 10–6 of the intensity of the absorbed light.
2. The decay curve follows bimolecular kinetics at 6.5°C. and reaction order 1.6 at 28°C.
3. This light saturates as does photosynthesis at higher light intensities and in about the same intensity range as does photosynthesis.
4. An action spectrum for light emitted as a function of the wave length of exciting light has been determined. It parallels closely the photosynthetic action spectrum.
5. The intensity of light emission was studied as a function of temperature and found to be optimal at about 37°C. with an activation energy of approximately 19,500 calories. Two-temperature studies indicated that the energy may be trapped in the cold, but that temperatures characteristic for enzymatic reactions are necessary for light production.
6. Illumination after varying dark periods showed initial peaks of varying height depending on the preceding dark period.
7. 5 per cent CO2 reversibly depresses the amount of light emitted by about 30 per cent. About 3 minutes are required for this effect to reach completion at room temperatures.
8. Various inhibitors of photosynthesis were tested for their effect on luminescence and were all inhibitory at appropriate concentrations.
9. Irradiation with ultraviolet light (2537A) inhibits light production at about the same rate as it inhibits photosynthesis.
10. This evidence suggests that early and perhaps later chemical reactions in photosynthesis may be partially reversible.
ACTION SPECTRA FOR PHOTOREACTIVATION OF ULTRAVIOLET-IRRADIATED ESCHERICHIA COLI AND STREPTOMYCES GRISEUS
Authors: Kelner Albert 
Published: May 2004

Action spectra for photoreactivation (light-induced recovery from ultraviolet radiation injury) of Escherichia coli B/r and Streptomyces griseus ATCC 3326 were determined. The spectral region explored was 365 to 700 mµ.
The action spectrum for S. griseus differed from that for E. coli, indicating that the chromophores absorbing reactivating energy in the two species were not the same. Reactivation of S. griseus occurred in the region 365 mµ (the shortest wave length studied) to about 500 mµ, with the most effective wave length lying near 436 mµ. This single sharp peak in the spectrum at 436 mµ suggested the Soret band typical of porphyrins. Reactivation of E. coli occurred in the region 365 to about 470 mµ, with the most active wave length lying near 375 mµ. The single, non-pronounced peak near 375 was probably not due to a Soret band, and the identification of the substance absorbing reactivating light in E. coli is uncertain.
In neither species was the region 500 to 700 mµ active.
The implications of these action spectra and their differences are discussed.
STUDIES OF NERVE PROTEINS. ISOLATION AND PHYSICOCHEMICAL CHARACTERIZATION OF A PROTEIN FROM LOBSTER NERVE
Authors: Maxfield Myles 
Published: May 2004

1. A procedure is described by which several protein constituents may be obtained from extracts of lobster claw nerves. One of these fractions, designated fraction A, representing 10 per cent of the total non-dialyzable material of the extracts, has been obtained in relatively (85 per cent) pure form.
2. This component has been characterized with respect to its physicochemical properties, particle shape, dimensions, and absorption spectrum.
THE LIMITING MECHANISM IN TARSAL CHEMORECEPTION
Authors: Dethier V. G. 
Published: May 2004

Rejection thresholds of eight primary alcohols applied to the tarsal chemoreceptors of the blowfly Phormia regina Meigen and the ovipositor of Gryllus assimilis Fab. have been determined. Three different solvents for the alcohols have been used: water, ethylene glycol, and mineral oil. The comparative stimulating effectiveness of the alcohols assumes a different aspect with each different solvent. In oil the range of thresholds from methanol to octanol extends over less than one log unit as compared with the corresponding thresholds in water which extend over four log units. In glycol the thresholds extend over two and one half log units only. When water is employed as a solvent, the line which describes the relationship between threshold concentration and chain length of the compound exhibits a sharp break at or near butanol. No such discontinuity is evident when glycol or oil is employed as solvent. This is offered as evidence supporting the hypothesis that the limiting mechanism in tarsal chemoreception involves a two phase system whereby highly water-soluble compounds gain access to the receptor through an aqueous phase and the larger lipoid-soluble molecules chiefly through a lipoid phase. Additional facts which support this idea are gained from data which show that the inflection in the curve occurs at different points with different species of insects and is conspicuously absent in the case of man.
When thresholds in aqueous solutions are converted from molar concentrations to activities, it is clear that the relation of equal physiological effect at equal thermodynamic activities does not apply here. The lower members of the series stimulate at progressively increasing activities up to pentanol and then at progressively decreasing activities. Furthermore, the ratio of water threshold to oil threshold exhibits no obvious agreement with the water/oil partition coefficients determined experimentally. These results indicate either that the limiting process of chemoreception in these insects does not depend upon the establishment of an equilibrium or that some kinetic effect is obscuring an underlying relationship which does so depend.
ELECTROPHORESIS OF PROTEINS ON FILTER PAPER
Authors: Kunkel Henry G. , Tiselius Arne 
Published: May 2004

A simplified procedure for filter paper electrophoresis is described in which disturbing factors such as evaporation, heating, buffer concentration gradients, and pH changes in the electrode vessels were reduced to a minimum. Artificial mixtures of highly purified proteins could be separated and the components isolated. The application of the method to a variety of studies on serum proteins is demonstrated. Protein concentration in paper segments was determined by two different methods of protein estimation. Curves were obtained showing the same five major peaks for normal serum as found by the classical methods of free electrophoresis. Comparisons were made of the areas of the various components under the curves obtained with the different methods.
Two dimensional electrophoresis was applied to serum and serum components. It proved of value in demonstrating the heterogeneity of fractions such as the γ-globulin of serum.
The polysaccharide dextran was used as an index of the extent of electro-osmotic flow during the course of the various experiments. The ratio of the distance of electroosmotic flow and the distance of protein migration was shown to be constant for a given type of paper. For serum albumin on Munktell 20 paper this ratio was 0.35. A formula for mobilities applicable to liquid in a highly porous supporting medium is presented. Mobility values for human serum albumin at various pH levels on paper showed approximate agreement with those obtained in free solution giving a similar isoelectric point.
CONTINUOUS CONDUCTION OF IMPULSES IN PERIPHERAL MYELINATED NERVE FIBERS
Authors: Laporte Y. 
Published: May 2004

1. Conduction of impulses in peripheral myelinated fibers of a nerve trunk is a continuous process, since with uninjured nerve fibers: (a) within each internodal segment the conduction time increases continuously and linearly with increasing conduction distance; (b) the presence of nodes of Ranvier does not result in any detectable discontinuity in the conduction of the impulse; (c) the ascending phase of the spike always has an S shape and never presents signs of fractionation; (d) the shape and magnitude of the spike are constant at all points of each internodal segment.
2. Records have been presented of the external logitudinal current that flows during propagation of an impulse in undissected single nerve fiber (Fig. 6).
3. Propagation of impulses across a conduction block occurs with a readily demonstrable discontinuity.
PHAGE FORMATION IN STAPHYLOCOCCUS MUSCAE CULTURES
Authors: Price Winston H. 
Published: May 2004

1. Under a variety of conditions in which cells are infected with one or a few virus particles and the host cells are killed, but no infective particles or virus material is formed as indicated by plaque count, one-step growth curve, or protein or desoxyribonucleic determinations, the cells neither lyse nor release ribonucleic acid into the medium.
2. The "killing" effect of S. muscae phage is separate from its lytic property.
3. The release of ribonucleic acid into the medium is not simply due to the killing of the cell by the virus, and ribonucleic acid is never found in the medium unless virus material is synthesized.
4. Infected cells of S. muscae synthesizing virus release ribonucleic acid into the medium before cellular lysis begins and before any virus is liberated.
5. The higher the phage yield the more ribonucleic acid is released into the medium before any virus is released.
6. Phage may be released from one strain of Staphylococcus muscae without cellular lysis, although bacterial lysis begins shortly after the virus is released. In another strain, infected under similar conditions, virus liberation occurs simultaneously with cellular lysis.
7. The viruses liberated from both bacterial strains appear to be the same in so far as they cannot be distinguished by serological tests, have the same plaque type and plaque size, and need the same amino acids added to the medium in order to grow. Furthermore, the virus liberated from one strain can infect and multiply in the other strain and vice versa.
8. It is suggested that virus synthesis, in S. muscae cells infected with one or a few phage particles, leads to a disturbance of the normal cellular metabolism, resulting in lysis of the host cell.
SOME ASPECTS OF PROTOPLASMIC MOTION
Authors: Osterhout W. J. V. 
Published: May 2004

In Nitella the protoplasm forms a layer about 15 microns thick surrounding a large central vacuole. The outer part of the protoplasm is a gel, the inner layer is a sol which is in continual motion travelling the entire length of the cell in opposite directions on opposite sides and thus making a complete circuit (cyclosis).
If we have a cell devoid of motion and if we regard the protoplasm in any region as made up of successive portions, A, B, C, D, etc., as we pass from left to right) we may suppose that a reaction starts in B which results in a temporary loss of volume by electrostriction, so that liquid moves from A to B to fill the void thus created. The same reaction then occurs at C causing liquid to flow from B to C and so on.
The protoplasmic movement can be controlled by agents which affect the viscosity of the protoplasm or the reactions which cause the flow. Certain reagents such as lead acetate stop the flow temporarily.
When the motion is stopped in any region by killing or by applying lead acetate, the motion goes on for a time in adjoining regions. When motion stops in all of the cell or in certain parts, it resumes in the same direction as it had before stoppage occurred. Under normal conditions each of the two sides of the cell (on opposite sides of the white line) has its own characteristic direction of motion which remains unchanged after a temporary stoppage of motion in all parts of the cell. Hence the two sides differ and we have what may be called lateral polarity. There is also longitudinal polarity as the opposite ends of the cell are unlike since shoots grow out at one end and roots at the opposite end.
The explanation suggested to account for motion in Nitella may apply to other kinds of motion including the motion of cilia and of flagella.
THE ISOLATION OF CELL NUCLEI IN NON-AQUEOUS MEDIA
Authors: Allfrey V. , Stern H. , Mirsky A. E. , Saetren H. 
Published: May 2004

1. A modified Behrens procedure is described for the isolation of nuclei from avian erythrocytes and from the liver, kidney, thymus, pancreas, heart, and intestinal mucosa of the calf or horse.
2. The purity of these nuclei has been established by staining reactions, enzyme studies, and immunological tests for serum proteins.
3. Evidence is presented to show that a transport of cytoplasmic proteins into the nucleus does not occur during the isolation.
4. Nuclei prepared in non-aqueous media contain considerably more protein and a very different enzyme composition from that observed in nuclei prepared by "homogenization" techniques in dilute citric acid.
5. The suitability of nuclei prepared in organic media for the study of intracellular enzyme distribution is discussed.
THE INTRACELLULAR GROWTH OF BACTERIOPHAGES
Authors: Doermann A. H. 
Published: May 2004

A method is described for liberating and estimating intracellular bacteriophage at any stage during the latent period by arresting phage growth and inducing premature lysis of the infected cells. This is brought about by placing the infected bacteria into the growth medium supplemented with 0.01 M cyanide and with a high titer T6 lysate. It was found in some of the later experiments that the T6 lysate is essential only during the first half of the latent period. Cyanide alone will induce lysis during the latter part of the latent period.
Using this method on T4-infected bacteria it is found that during the first half of the latent period no phage particles, not even those originally infecting the bacteria, are recovered. This result is in agreement with the gradually emerging concept that a profound alteration of the infecting phage particle takes place before reproduction ensues. During the second half of the latent period mature phage is found to accumulate within the bacteria at a rate which is parallel to the approximately linear increase of intracellular DNA in this system. However, the phage production lags several minutes behind DNA production.
When 5-methyltryptophan replaced cyanide as the metabolic inhibitor, similar results were obtained. The curves were, however, displaced several minutes to the left on the time axis.
The results are compared with Latarjet's (16) data on x-radiation of infected bacteria and with Foster's data (18) concerning the effect of proflavine on infected bacteria. Essential agreement with both is apparent.
AN ANALYSIS OF THE INACTIVATION OF THE FROG SPERM NUCLEUS BY TOLUIDINE BLUE
Authors: Briggs Robert 
Published: May 2004

Toluidine blue, applied to frog sperm under appropriate conditions, inactivates specifically the sperm nucleus, leaving the extranuclear parts of the cell undamaged. Thus, the dye-treated spermatozoa stimulate eggs to cleave normally, but contribute no chromosomes to the resulting embryos, which develop as typical gynogenetic haploids.
The concentration of dye required to produce this inactivation varies with pH. Measurements made over the entire pH range which can be tolerated by sperm cells showed that in the lower part of the range (5 to 7) the effective dye concentration was about 5 x 10–6 M; in the intermediate range (7 to 8.5) it was 1 x –6 to 1 x –7 M; and for the higher pH values (8.5 to 10.0) it was about 5 x –8 M. Using sperm suspensions containing 1500 cells per c. mm. these concentrations of dye produced specific inactivation of the sperm nuclei within 7 to 60 minutes at 18°C.
Tests of the reversibility of the inactivation were made by transferring the sperm from the dye to a dilute Ringer's solution after a known degree of inactivation had been produced. Following removal of the dye the sperm cells were tested on eggs over a period of 2 hours. During this time there was no indication of a reversal of the inactivation.
Microscopic observations of sperm treated with –5 M or 5 X –5 M dye show that the dye is taken up by the sperm nucleus, which is faintly but definitely stained. The dye appears to be uniformly distributed in the nucleus, while extranuclear structures remain unstained.
Measurements of the amount of dye bound per sperm nucleus indicate that the minimal quantity required for complete inactivation is about 6.7 x –18 mole, while the maximal amount which can be bound without injury to extranuclear structures is about 1.5 x –16 mole. The value obtained for the minimal requirement (6.7 X 16 mole = 4 X 6 molecules) suggests that there are roughly 4 million binding sites in the nucleus which, when blocked by dye molecules, somehow prevent the sperm chromosomes from participating in the development of the egg.
STUDIES ON ISOLATED CELL COMPONENTS
Authors: Anderson Norman G. , Wilbur Karl M. 
Published: May 2004

1. The effects of morganic ions, electrolyte concentration, and pH on the appearance and volume of the isolated rat liver nucleus have been studied. Nuclei were isolated by differential centrifugation in a buffered salt-sucrose mixture at pH 7.1. Nuclear volumes were determined photographically.
2. In solutions of NaCl, of KCl, and in potassium phosphate buffers the nuclear volume decreased markedly with an increase in concentration from 0.001 M to 0.05 M but remained essentially constant with further increase in concentration to 1.0 M. The effects of CaCl2 and MgCl2 differed from those of NaCl and KCl in that a smaller volume was obtained in concentrations less than 0.15 M, and in the case of CaCl2 an increase in volume was obtained in more concentrated solutions. The volume changes are considered to be due primarily to ionic effects on the nuclear colloids rather than to osmotic behavior.
3. Treatment of nuclei with DNAase prevented the characteristic volume changes resulting from ion effects, suggesting the importance of DNA in nuclear volume changes.
4. The optical changes in isolated nuclei in various concentrations of KCl, NaCl, CaCl2, MgCl2, and in potassium phosphate buffers as observed under phase contrast illumination are described. CaCl2 gave the most marked nuclear changes from the conditions in the uninjured cell and caused shrinkage and granulation in 0.001 M concentration. The effects of CaCl2 were also manifested in 0.88 M sucrose, in mixtures with monovalent salts, and in serum. Changes in nuclear volume and optical appearance which occurred in salt solutions and in 0.1 N HCl were readily reversible.
5. Nuclear volume remained constant between pH 8.91 and 5.12 and decreased in more acid solutions.
6. Sucrose had no appreciable osmotic effect, and in hyperosmotic solution. (0.88 M) nuclei showed swelling and rupture comparable to that in distilled water.
7. The results are considered in relation to the requirements of nuclear isolation media.
8. Rat liver nuclei isolated in a buffered salt-sucrose medium by differential centrifugation exhibited a pattern of size distribution similar to that of fixed nuclei but were of considerably larger volume. The ratio of the volumes of the peak frequencies of the two chief size groups was 1:1.9.
THE FLUORESCENCE SPECTRA OF RED ALGAE AND THE TRANSFER OF ENERGY FROM PHYCOERYTHRIN TO PHYCOCYANIN AND CHLOROPHYLL
Authors: French C. S. , Young Violet K. 
Published: May 2004

1. The fluorescence spectra of the alga Porphyridium have been recorded as energy distribution curves for eleven different incident wave lengths of monochromatic incident light between wave lengths 405 and 546 mµ.
2. In these spectra chlorophyll fluorescence predominates when the incident light is in the blue part of the spectrum which is strongly absorbed by chlorophyll.
3. For blue-green and green light the spectrum excited in Porphyridium contains in addition to chlorophyll fluorescence, the fluorescence bands characteristic of phycoerythrin and of phycocyanin.
4. From these spectra the approximate curves for the fluorescence of the individual pigments phycoerythrin, phycocyanin, and chlorophyll in the living material have been derived and the relative intensity of each of them has been obtained for each of the eleven incident wave lengths.
5. The effectiveness spectrum for the excitation of the fluorescence of these three pigments in vivo has been plotted.
6. From comparisons of the effectiveness spectrum for the excitation of each of these pigments it appears that both phycocyanin and chlorophyll receive energy from light which is absorbed by phycoerythrin.
7. It is suggested that phycocyanin may be an intermediate in the resonance transfer of energy from phycoerythrin to chlorophyll.
8. Since phycoerythrin and phycocyanin transfer energy to chlorophyll, it appears probable that chlorophyll plays a specific chemical role in photosynthesis in addition to acting as a light absorber.
STUDIES ON THE MECHANISM OF THE PHOTOSENSITIZED INACTIVATION OF E. COLI AND REACTIVATION PHENOMENON
Authors: Heinmets F. , Vinegar R. , Taylor W. W. 
Published: May 2004

In order to find a more satisfactory interpretation of the phenomenon of photosensitized inactivation of bacteria, studies were performed under various experimental conditions on methylene blue and E. coli. In summary the findings are as follow:—
1. The dye is absorbed by the bacteria according to the Langmuir isotherm and can be removed by ionic substitutions; the dye binding to the bacteria is predominantly ionic; the dye-bacteria complex produces a new absorption peak in the 610 mµ wave length region, and the action spectrum corresponds to the spectral absorption of the dye-bacteria complex.
2. There is an optimum dye concentration range for the photosensitized inactivation.
3. Photosensitized inactivation of bacteria can take place both in the frozen and liquid states and the presence of oxygen is essential to the inactivation process.
4. Hydrogen peroxide, formed by reoxidation of the reduced methylene blue, does not inactivate bacteria.
5. Following the photosensitized inactivation, E. coli lose their ability to reduce the methylene blue in the presence of various hydrogen donors, suggesting that enzymes are involved in the inactivation process.
6. Bacteria inactivated by photosensitization can be reactivated by prolonged storage after irradiation; the recovery rate increases with increasing temperature (maximum 37°), and is also influenced by the presence of various hydrogen donors.
In view of collected experimental data, the basic reaction mechanisms are analyzed in photosensitized inactivation. The first step of the reaction seems to be excitation of the dye-bacteria, or dye-bacteria oxygen complex, by a photon which produces an activated complex. In such a state, molecular oxygen is capable of producing an oxidizing reaction, which results in the inactivation of the bacteria. Some aspects of the detailed reactions taking place at the cell surface are discussed.