bluuebunny/crossref_metadata_2025 huggingface dataset:
STUDIES ON ISOLATED CELL COMPONENTS
Authors: Anderson Norman G. , Wilbur Karl M.
Published: May 2004

1. The addition of heparin to rat liver, kidney, or brain nuclei has been found to bring about the release of a gel. Chemical analysis and histochemical studies on whole homogenates and isolated nuclei demonstrated that the material released by heparin contained desoxyribonucleic acid (DNA) and protein. The action of heparin on nuclei is interpreted as the result of a combination with the basic proteins of the nucleus with a consequent displacement of DNA.

2. The addition of heparin to a finely divided dilute liver homogenate prepared in a phosphate-sucrose solution at pH 7.1 brings about a marked increase in viscosity which reaches a maximum in 6 to 8 minutes at 23° and then declines.

3. The concentration threshold for the viscosity effect was 0.1 mg. per 100 mg. fresh rat liver, with further increases in viscosity at higher heparin concentrations. Over a period of several hours a marked decrease in response to heparin was observed in homogenates stored at 0°.

4. Fractionation of the homogenate demonstrated that the viscosity increase was due to the presence of the nuclei alone, other components showing no effect. Microscopic observation showed that the increase in viscosity was associated with the appearance of a clear gel around nuclei treated with heparin.

5. Heparin brought about the release of DNA from the nuclei of incubated rat liver, kidney, and brain homogenates. In some instances over half the DNA is found in the supernatant after high speed centrifugation (20 minutes, 21,000 x g).

6. No correlation was found between anticoagulant activity of heparin preparations and their effectiveness in causing an increase in the viscosity of liver homogenates. Desulfated heparin produced none of the results described here for heparin.
NUCLEIC ACID SYNTHESIS IN MUSTARD GAS-TREATED E. COLI B
Authors: Herriott Roger M. ,   With the Technical Assistance of James L. Barlow
Published: May 2004

Following exposure to dilute aqueous solutions of mustard gas, suspensions of E. coli B do not produce DNA although PNA is formed in nearly normal amounts. When the treated cells are infected with virus T2, DNA is synthesized and RNA is not. The DNA formation continued after the virus titer reached a maximum.
TISSUE CULTURE MEDIA
Authors: Jacquez John A. , Barry Enid
Published: May 2004

1. Human placental cord serum contains a factor or factors necessary for active growth of fibroblasts in tissue culture and a factor which prevents the appearance of a characteristic toxicity.

2. The growth-promoting factor(s) is stable to heating to 60°C. for 30 minutes and is associated with the euglobulin fraction of the serum.

3. Extraction of dried cord serum with benzene, chloroform, and ether does not cause any decrease in growth-promoting activity.

4. Sera from hypophysectomized, adrenalectomized, and thyroid-parathyroidectomized rats show as much growth-promoting activity as normal rat sera.

5. Bovine gamma globulins, anterior pituitary growth hormone, and insulin do not replace the serum growth factor.

6. The toxicity-preventing factor is serum albumin.

7. Evidence is presented that the toxicity is due to free fatty acids in the medium and that serum albumin acts by binding the fatty acids.
ENZYME SYSTEMS IN TETRAHYMENA GELEII S
Authors: Seaman Gerald R.
Published: May 2004

The rates of activity of the dehydrogenase systems in Tetrahymena, which are concerned with carbohydrate oxidation, in descending order of activity are: lactic > isocitric > succinic = glucose > glucose-6-phosphate = 6-phosphogluconic = malic > glutamic = cytochrome linked α-glycerophosphate dehydrogenase.

No evidence was obtained to indicate the presence of DPN linked α-glycerophosphate dehydrogenase.
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.
GALVANOTAXIS OF SLIME MOLD
Authors: Anderson John D.
Published: May 2004

The plasmodium of Physarum polycephalum reacts to direct current by migration toward the cathode. Cathodal migration was obtained upon a variety of substrata such as baked clay, paper, cellophane, and agar with a current density in the substratum of 1.0 µa./mm.2 Injury was produced by current densities of 8.0 to 12.0 µa./mm.2 The negative galvanotactic response was not due to electrode products. Attempts to demonstrate that the response was due to gradients or orientation in the substratum, pH changes in the mold, cataphoresis, electroosmosis, or endosmosis were not successful. The addition of salts (CaCl2, LiCl, NaCl, Na2SO4, NaHCO3, KCl, MgSO4, sodium citrate, and sea water) to agar indicated that change of cations had more effect than anions upon galvanotaxis and that the effect was upon threshold values. K ion (0.01 M KCl) increased the lower threshold value to 8.0 µa./mm.2 and the upper threshold value to 32.0 µa./mm.2, whereas the Li ion (0.01 M LiCl) increased the lower threshold to only 4.0 µa./mm.2 and the upper threshold to only 16.0 µa./mm.2 The passage of electric current produced no increase in the rate of cathodal migration; neither was there a decrease until injurious current densities were reached. With increase of subthreshold current densities there was a progressive decrease in rate of migration toward the anode until complete anodal inhibition occurred. There was orientation at right angles to the electrodes in alternating current (60 cycle) with current density of 4.0 µa./mm.2 and in direct current of 5.0 µa./mm.2 when polarity of current was reversed every minute. It is concluded that the negative galvanotactic response of P. polycephalum is due to inhibition of migration on the anodal side of the plasmodium and that this inhibition results in the limitation of the normal migration of the mold to a cathodal direction. The mechanism of the anodal inhibition has not been elucidated.
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.
HEMOLYSIS CONSIDERED AS A PROGRESSIVE REACTION IN A HETEROGENEOUS SYSTEM
Authors: Ponder Eric , Cox R. T.
Published: May 2004

It is demonstrated, without the use of special assumptions, that red cells are heterogeneous with respect to their resistance to at least certain lysins, that the reaction between the cell components and the lysin is virtually irreversible in some cases but reversible, although to different extents, in others, and that the lysin initiates a process in the cell which is not adequately described by the terms reversible and irreversible, but rather by the term progressive. Progressive reactions, i.e. reactions which cannot be stopped once they are well under way, may be looked for in systems which have structure, and in which local reactions occurring at strategic points lead to disproportionate results.
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.
ON THE NATURE OF SPOROGENESIS IN SOME AEROBIC BACTERIA
Authors: Hardwick W. A. , Foster J. W.
Published: May 2004

Washed vegetative cells of various species of aerobic spore-forming bacteria sporulate abundantly when shaken in distilled water in air. The spores thus formed possess the same heat resistance as spores formed in a complete growth medium. Various factors influencing sporogenesis in water are described. Glucose in low concentration completely suppresses sporogenesis under these conditions and the suppression is relieved by the presence of ammonia as an exogenous source of nitrogen. Various amino acid and purine antimetabolite analogues inhibit sporogenesis and their inhibitory effects are completely reversed by much smaller amounts of the corresponding metabolites. Sporogenesis is thus regarded as a de novo synthesis of spore proteins from preexisting endogenous (enzyme) proteins. Cells low in protein fail to sporulate and the capacity of the cell to adaptively attack maltose and trehalose is strongly interfered with after the cell is irreversibly committed to sporulation, but not before that. Evidence is advanced supporting the hypothesis that sporogenesis is an endogenous process which commences when the supply of exogenous energy and carbon is depleted. It utilizes low molecular weight nitrogenous substances liberated by the degradation of preexisting enzyme proteins of the vegetative cell. Sporogenesis and adaptive enzyme formation are regarded as competitive synthetic processes, both utilizing endogenous enzyme proteins. The events of sporogenesis suggest that this process may be an adaptive protein synthesis, analogous to adaptive enzyme synthesis.
ON THE ENERGETICS OF THE PHOTOSYNTHESES IN GREEN SULFUR BACTERIA
Authors: Larsen Helge , Yocum C. S. , van Niel C. B.
Published: May 2004

The quantum efficiency of photosynthesis by the green sulfur bacterium, Chlorobium thiosulfatophilum, has been determined in systems in which thiosulfate, tetrathionate, and molecular hydrogen served as electron donors. It was found that about 10 ± 1 quanta are used for the assimilation of 1 molecule of CO2, and that the quantum number is independent of the nature of the electron donor. These results are considered as support for the view that also in the bacterial photosyntheses the primary photochemical reaction consists in the photolysis of H2O, and that the chemical energy released during the oxidation of the electron donor is not utilized for CO2 assimilation. Hence the photosynthetic processes of the green sulfur bacteria are thermodynamically less efficient than is green plant photosynthesis.
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.
GEOMETRICAL ISOMERS OF RETINENE
Authors: Hubbard Ruth , Gregerman Robert I. , Wald George
Published: May 2004

Five crystalline retinenes have been isolated, which have every appearance of being cis-trans isomers of one another. They are all-trans retinene; three apparently mono-cis isomers: neoretinenes a and b and isoretinene a; and isoretinene b, an apparently di-cis isomer.

The absorption spectra of these substances display the relations expected of cis-trans isomers. The main absorption band is displaced 5.5 to 7 mµ toward shorter wave lengths for each presumptive cis linkage. Some of the presumptive cis isomers also display a cis peak at 255 to 260 mµ. All five substances yield an identical blue product on mixing with antimony chloride. All of them are converted by light to what appears to be an identical mixture of stereoisomers. Heat isomerizes them very slowly; only neoretinene b exhibits large changes on heating at 70°C. for 3 hours. The various isomers have been extensively interconverted by gentle procedures, and all of them have been converted to all-trans retinene.

The present theory of cis-trans isomerism in carotenoids predicts the existence of four stable isomers of retinene. Instead we seem to have five—specifically three mono-cis forms where two are expected. There is no doubt that all these substances are closely related isomers of one another. The only point in question is whether they differ in part by something other than cis-trans configuration. One possibility, as yet little supported by evidence, is that isomerization between ß- and α-ionone rings may be involved. If, however, as seems more likely, all these substances are geometrical isomers of one another, some modification is needed in the present theory of configurational relationships in this class of compounds.
SPORULATION IN DISTILLED WATER
Authors: Powell Joan F. , Hunter J. R.
Published: May 2004

Spores are formed when vegetative cells of sporing aerobes are shaken with distilled water at 37°. These spores are derived from the small number of cells which survive lysis. The sporulation process involves increase and concentration of solid material in the cell, and is achieved at the expense of the products of lysis of 80 to 90 per cent of the resuspended cells.
RELATION OF METABOLISM OF FROG SKIN TO CELLULAR INTEGRITY AND ELECTROLYTE TRANSFER
Authors: Levinsky Norman G. , Sawyer Wilbur H.
Published: May 2004

1. The transport of sodium by frog skin and the maintenance of normal potassium levels within the cells of the skin are both dependent on metabolism and on a supply of phosphate bond energy.

2. Except for the common requirement of phosphate bond energy, the transfer mechanism for sodium and the mechanism for maintaining intracellular potassium appear to be independent.

3. The xanthines specifically inhibit the sodium transfer mechanism; at higher concentrations, they depress metabolism and cause loss of potassium from the skin.
THE MECHANISM OF THE SYNTHESIS OF ENZYMES
Authors: Koppel J. L. , Porter C. J. , Crocker Bruce F.
Published: May 2004

1. An experimental system suitable for the study of enzyme formation has been described.

2. The formation of ß-galastosidase in E. coli B could be induced by lactose, melibiose, D-galactose and ß-methyl-D-galactoside.

3. Lactose-induced ß-galactosidase formation was found to be inhibited by D-glucose, D-mannose, D-fructose, D-arabinose, and raffinose.

4. The utilizable structural analogue, D-glucose, was found to either stimulate or inhibit ß-galactosidase formation depending upon its concentration. D-Arabinose, on the other hand, a non-utilizable structural analogue, is only capable of inhibiting, whereas succinic acid, a structurally unrelated energy source, is only capable of stimulating ß-galactosidase formation.

5. D-Arabinose inhibition of lactose-induced ß-galactosidase formation was found to be of the competitive type.

6. Some of the implications of these findings have been discussed.
CHLOROPHYLL MONOLAYERS IN CHLOROPLASTS
Authors: Wolken J. J. , Schwertz F. A.
Published: May 2004

1. The data on the fine structure of the chloroplasts and the chlorophyll analyses, in two algal flagellates, Euglena gracilis and Poteriochromonas stipitata, are consistent with the assumption that the chlorophyll molecules are arranged in monomolecular layers at the interfaces between the lipid (dense) and the aqueous protein complex layers.

2. The cross-sectional area available to each chlorophyll molecule in the chloroplasts of Euglena and Poteriochromonas was found to be 222 x 10–16 cm2. and 246 x 10–16 cm2. By comparison, the cross-sectional area of the hydrophilic head of the chlorophyll molecule is approximately 240 x 10–16 cm2.

3. The model of the molecular network depicted in Text-fig. 1 is purely speculative. It predicts a lower limit for the number ratio of chlorophyll to other pigment molecules of about 1:1 and a weight ratio of 2:1. A loose packed structure such as that shown in Text-fig. 1 predicts a weight ratio of 4:1 to 6:1. These values bracket the large majority of experimental values found for this ratio.

The relative constancy of the number of chlorophyll molecules per chloroplast and the volume of the chloroplast indicated by the data in Table III suggest that chloroplasts probably possess a similar structural arrangement in a variety of photosynthetic microorganisms and plants.
THE ROLE OF PHOSPHOCREATINE AND ADENOSINE-TRIPHOSPHATE IN MUSCULAR CONTRACTION
Authors: Bozler Emil
Published: May 2004

In the presence of 20 mM PC a strong contraction is produced in glycerol-extracted muscle fibers by ATP and AMP in concentrations as low as 10–6 M per liter. At low concentrations of nucleotide tension rises very slowly. This rise is interpreted as being due to absorption of nucleotide by the contractile elements. AMP gives an S-shaped tension curve, indicating that the conversion of AMP into ATP is an autocatalytic process. Tension is maintained in a contracted muscle even in PC solutions free of ATP. PC alone produces a contraction if applied within 5 minutes after ATP has been washed out from a contracting muscle. It is concluded from these results that PC is the substrate for the enzymatic activity of the contractile elements and that this activity depends on the presence of bound nucleotide which acts as an energy transfer mechanism.

PC accelerates relaxation which is caused by ATP under certain conditions. In the presence of PC even very low concentrations of ATP can produce relaxation. A strong contraction can be produced under these conditions by the addition of Ca ions. These observations support the conclusion that relaxation depends on the rephosphorylation of nucleotide bound by the contractile elements.
SYNTHESIS OF PROTEIN IN THE PANCREAS
Authors: Allfrey V. , Daly Marie M. , Mirsky A. E.
Published: May 2004

1. The ribonucleoprotein of the microsome fraction which sediments at 40,000 R.P.M. as a pellet (and which is referred to as the pellet material) has been studied with reference to its role in protein synthesis in the pancreas.

2. In pellet material nucleic acid and protein form a definite complex as shown by its electrophoretic behavior and unchanging composition under various conditions.

3. Protein of pellet material is not especially rich in the diamino acids.

4. Evidence is brought forward indicating that the protein component of pellet material takes part in the general process of protein synthesis in the cell.

(a) The well known correlation between quantity of RNA and rate of protein synthesis in a tissue implicates the protein of the pellet material, for most of the RNA in the pancreas and other tissues is in this material.

(b) Uptake of isotopically labelled glycine by the pellet material, confirming results of previous workers, is for short periods greater than in other protein fractions.

(c) Comparing the pellet materials of pancreas, liver, and kidney—three tissues with vastly different rates of protein synthesis, in the sequence given—there is a correlation between the quantity of RNA in the pellet and the rate of protein synthesis in the tissue; a similar correlation between quantity of RNA in the pellet material and rate of N15-glycine uptake by the protein component of the pellet; and finally, the level of uptake by total protein varies with the tissue and is related to the uptake of N15-glycine by protein of the pellet.

5. In the pancreas a distinction can be made between proteins synthesized for secretion and the nucleoprotein of the pellet (not found in the secretion) which, however, takes part in the synthetic process, as shown by the fact that the N15 uptake by protein of the pellet is increased when the synthesis of digestive enzymes is stimulated by secretion.

6. The time course of N15 uptake by proteins of the pancreas indicates that pellet protein serves as precursor material in the synthesis of the secretory proteins.

7. Rate of uptake of N15-glycine by the purines of RNA of the pellet material is not correlated with uptake by the protein.

8. The uptake of C14-alanine by an in vitro system of microsomes + mitochondria is impaired by preincubation of the microsomes with ribonuclease. This is direct experimental evidence for the dependence of protein synthesis upon the presence or intactness of ribonucleic acid in the microsomes.
SOLUBLE ENZYMES OF NUCLEI ISOLATED IN SUCROSE AND NON-AQUEOUS MEDIA
Authors: Stern Herbert , Mirsky A. E.
Published: May 2004

Nuclei of calf thymus and liver and of rat liver were isolated in sucrose media and a number of their properties studied in relation to those of corresponding nuclei isolated in non-aqueous media with a view to determining their capacity to retain soluble components.

The best preparations of sucrose nuclei were obtained from calf thymus. Cytochrome oxidase measurements and DNA/N ratios were far less sensitive than microscopic examination as indicators of purity when rat liver and calf thymus nuclei were compared. No satisfactory preparation of calf liver nuclei was obtained, contamination with whole cells having been appreciable; such preparations, nevertheless, could be used to advantage in the tests undertaken.

DNA content of thymus nuclei isolated in sucrose was much the same as that of non-aqueous ones, pointing to a retention of soluble protein under aqueous conditions of isolation. That this net retention of protein was not due to the impermeability of the nuclear membrane was shown by the hydrolysis of the DNA upon addition of some crystalline DNAase to a sucrose suspension of nuclei.

A comparative study of liver and thymus nuclei isolated in aqueous and non-aqueous media with respect to the soluble enzymes glucose-6-phosphate dehydrogenase, adenosine deaminase, and nucleoside phosphorylase yielded the following results:

1. Lyophilization of sucrose-isolated nuclei and their extraction with the organic solvents used in the non-aqueous procedure did not inactivate any of the enzymes tested. In the case of thymus the reverse was true, there being a marked increase in activity of all the enzymes studied.

2. In thymus, nucleoside phosphorylase and adenosine deaminase were active to approximately the same extent in nuclei isolated by either procedure. Glucose phosphate dehydrogenase alone was more active in sucrose-isolated nuclei, pointing to the possibility of an adsorption of this enzyme.

3. In rat liver nuclei isolated in sucrose, lyophilization and treatment with organic solvents revealed only the presence of some dehydrogenase.

4. The washing out of soluble enzymes was most markedly demonstrated in the case of calf liver. Only traces of the nucleoside enzymes were found in the sucrose-isolated nuclei, and in the case of the dehydrogenase only a half of that present in the non-aqueous nucleus remained.

The main conclusions drawn were as follows:—

1. In sucrose media the nuclear membrane is ineffectual in preventing the inward or outward diffusion of protein.

2. The extent to which soluble proteins are retained by a nucleus isolated in sucrose appears to depend upon internal structural factors, such as the concentration of DNA in the nucleus.

3. With respect to determining the composition of nuclei in terms of soluble components, the sucrose isolation procedure is considered to be of indifferent merit and hence invalid for such a type of analysis.
TISSUE CULTURE STUDIES
Authors: Rosenberg Sheldon , Zitcer Elsa , Kirk Paul L.
Published: May 2004

A fraction of the ultrafilterable portion of chick embryo extract was isolated by alcohol extraction of a lyophilized powder of the ultrafiltrate followed by ion exchange removal of many of the inert components of the alcohol extract. This fraction contained 3 per cent of the ultrafilterable nitrogen but was capable of completely restoring the growth-promoting activity of dialyzed embryo extract, when tested with chick heart fibroblasts in roller tube cultures.

The low nitrogen content, shape of the ultraviolet absorption spectrum, and presence of few free amino acids, suggest that non-dialyzable compounds serve as the chief source of nutrition for this system.
THE MECHANISM OF THE SYNTHESIS OF ENZYMES
Authors: Porter C. J. , Holmes R. , Crocker Bruce F.
Published: May 2004

1. The pretreatment induction method of studying the formation of ß-galactosidase in E. coli B has been described.

2. It has been found that E. coli B cells have their maximum capacity to form ß-galactosidase, in response to a constant induction stimulus, when they are in the stationary phase of the growth cycle.

3. The concentration of inductor, the nature of the nitrogen source, the duration of the assimilatory phase, oxygen tension, and temperature are factors which affect, and may limit, the rate of ß-galactosidase formation.

4. When limitations imposed by these factors were removed, the time course of induced ß-galactosidase formation was strictly linear from the onset.

5. The implications of this finding were discussed and a new theory of the mechanism of enzyme formation has been proposed.

6. A very satisfactory method of synthesis of ortho-nitrophenol-α-D-galactoside has been described. This substance is a suitable chromogenic substrate for the specific determination of α-galactosidase activity.

7. Preliminary experiments using this substrate have confirmed the results of respiration studies and shown that in E. coli B α-galactosidase formation may be induced by ß- as well as by α-galactosides.