bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE ISOLATION OF A STAPHYLOCOCCAL PHAGE VARIANT SUSCEPTIBLE TO AN UNUSUAL HOST CONTROL
Authors: Ralston D. J. , Krueger A. P. 
Published: May 2004

A series of phage P1 variants was isolated from plaques developing on S. aureus WF 145. One in particular, phage 14, was studied in detail because its host range appeared to be dependent on the previous host of production; i.e., it was subject to a host control. When this phage was produced on host K1 its lysate assayed equally well on both 145 and K1 cells. When produced on host 145, however, it assayed manyfold higher on 145 than on host K1. All its particles adsorbed on K1 cells, but only a small percentage were able to produce plaques. No differences could be found in adsorption rates, latent periods, or burst sizes of the phage on the two hosts. No extracellular inactivating substances could be detected which could account for such changes, nor could the results be explained readily on a mutational basis, since distinct phage strains could not be isolated. The change in virus properties was found to occur in the first burst of singly infected host 145 cells, regardless of the previous host or its prior lytic abilities.
Heat inactivation destroyed activity for K1 cells more rapidly than for 145 cells. This was found to be a property of both the stock phage P1 and phage 14. Phage 14 could be heated until there remained particles which could multiply only on strain 145. When the plaques of such survivors were examined they were found to contain phage which could multiply on both hosts in a ratio characteristic of the original unheated preparation.
The data suggest that the observed changes were caused by a host control over the formation of a phage material(s) necessary for successful infection of host K1. Such a substance theoretically could be related to the labile material destroyed by heat and required for plaque formation on host K1.
GLUCOSE-6-PHOSPHATE AND 6-PHOSPHOGLUCONATE DEHYDROGENASES FROM EGGS OF THE SEA URCHIN, ARBACIA PUNCTULATA
Authors: Krahl M. E. , Keltch A. K. , Walters C. P. , Clowes G. H. A. 
Published: May 2004

1. Glucose-6-phosphate and 6-phosphogluconate dehydrogenases have been found in homogenates of Arbacia eggs; 95 per cent of the activity toward each substrate is recovered in the supernatant fraction after centrifuging at 20,000 g for 30 minutes.
2. With glucose-6-phosphate as substrate) the rate of TPN reduction by the supernatant fraction from 1 gm. wet weight unfertilized or fertilized eggs was 1.8 to 3.0 micromoles per minute; this rate is sufficient to support a rate of oxygen consumption 24 times that observed for unfertilized, and 6 times that for fertilized, eggs. Pentose was formed from glucose-6-phosphate at a rate 0.3 to 0.5 that of TPN reduction, when both rates were expressed as micromoles per minute.
3. The concentrations of glucose-6-phosphate and 6-phosphogluconate for half maximal activity were each approximately 0.00004 M for the respective enzymes in the supernatant fraction. Maximal activity toward 6-phosphogluconate was 50 to 60 per cent of that toward glucose-6-phosphate. Glucose-6-phosphate dehydrogenase activity was 50 per cent inhibited in presence of 0.00006 M 2,4,5-trichlorophenol.
4. Reduction of DPN by the supernatant fraction in presence of fructose-1,6-diphosphate and ADP was 0.1 to 0.2 micromoles per minute per gm. wet eggs, indicating that the glycolytic pathway can metabolize glucose-6-phosphate at about 5 per cent the rate at which it can be oxidized by the TPN system from unfertilized or fertilized Arbacia eggs.
5. Phosphoglucomutase, hexose isomerase, and a phosphatase for fructose-1,6-diphosphate also appear to be present in Arbacia eggs.
THE NON-VIRUS PROTEINS ASSOCIATED WITH TOBACCO MOSAIC VIRUS
Authors: Commoner Barry , Yamada Mas 
Published: May 2004

1. Exhaustive fractionation of leaves from tobacco plants systemically infected with TMV has led to the isolation of two non-virus proteins, B3 and B6, and the detection of a third, A4, which do not occur in comparable uninfected plants.
2. Components B3 and B6 have been found consistently in a series of ten extracts from plants grown over an 18 month period in all seasons of the year. It is concluded that these components are as characteristic of the infected plant as TMV itself.
3. As they occur in the initial extracts, the non-virus proteins are of low molecular weight (S20 ca. 3). On treatment, each component tends to form a high molecular weight polymer with an electrophoretic mobility considerably greater than that of the starting material. The high molecular weight derivatives of A4, B3, and B6 have been designated A8, B8, and B7 respectively. There is no evidence that these high molecular weight components occur as such in the infected leaf.
4. The non-virus proteins are free of nucleic acid and are not infectious. They cross-react immunochemically with TMV.
5. Compared with TMV content, the amounts of the non-virus proteins found in infected leaf are relatively small, falling in the range of 10 to 150 micrograms per gm. of tissue.
RELATIONSHIPS BETWEEN TOBACCO MOSAIC VIRUS AND THE NON-VIRUS PROTEINS
Authors: Commoner Barry , Rodenberg Sidney D. 
Published: May 2004

1. The non-virus proteins, A4, B3, and B6, characteristically found in tobacco leaf infected with TMV exhibit specific immunochemical cross-reactions with serum prepared against the virus. The close immunochemical relations which occur among these proteins do not extend to any normal tobacco leaf proteins.
2. The rate of appearance of the non-virus proteins in newly infected cultured leaf tissue at various times after inoculation has been determined by immunochemical techniques and by direct isolation of the proteins. Both methods give comparable results. The non-virus proteins appear abruptly at about 220 hours after inoculation, when the TMV content is about one-third its final value. The amount of A4 rises rapidly and then levels off. The B6 content rises rapidly and continuously over the course of the experiment. B3 appears last, and increases in amount considerably more slowly than A4 and B6.
3. The isotope contents of TMV, B3, and B6 which appear in given intervals after inoculation in newly infected leaf cultured in nutrient containing N15H4 have been compared. The isotope levels of concurrent TMV, B3, and B6 are identical within the experimental error. The isotope conditions employed in this experiment lead to the conclusion that this coincidence of N15 levels means that the virus and non-virus proteins are probably synthesized at about the same time from the same non-protein source of nitrogen.
4. Possible interpretations of the available data on the non-virus proteins are discussed. It is likely that one or more of these proteins represents small protein units which occur in the TMV nucleoprotein.As they exist in the infected leaf, the non-virus proteins are probably no longer available to the biochemical processes which lead to TMV synthesis. They are probably not precursors of TMV protein in a temporal sense.
AN APPLICATION OF AUTOCORRELATION METHODS TO THE INTERPRETATION OF INTESTINAL MOTILITY RECORDS
Authors: Small Melvin D. , Brean John W. , Farrar John T. 
Published: May 2004

The application of statistical communication techniques to the analysis of intestinal motility records has made available certain information that has heretofore been obscure. This information is:
1. A measure of total activity expressed in square millimeters of Hg.
2. The frequency and amplitude of segmental activity.
3. A measure of the random variations in the amplitude of the "segmental" waves.
4. A measure of random activity and the range and relative amplitudes of the frequencies making up this component.
POST-TETANIC POTENTIATION OF POLYSYNAPTIC REFLEXES OF THE SPINAL CORD
Authors: Wilson Victor J. 
Published: May 2004

The phenomenon of post-tetanic potentiation has been studied in the cat spinal cord with particular reference to polysynaptic responses. Following tetanization of dorsal roots, these reflexes show an increased response, as measured in terms of their voltage-time area, with a predominant change in the earlier reflex pathways. Both of these changes in the reflex discharge have a time course of 15 to 25 seconds.
Post-tetanic potentiation is also observed in response to stimulation of a dorsal rootlet following tetanization of another rootlet in the same or in a neighboring segment. This effect can be explained by post-tetanic changes in the terminals of secondary, and possibly higher order, internuncial cells, essentially similar to those changes in the primary afferent terminals which give rise to potentiation of the monosynaptic reflex.
OLFACTORY NERVE FIBERS
Authors: Gasser Herbert S. ,   With the Collaboration of G. E. Palade
Published: May 2004

Cross sections of olfactory nerves present a unique appearance. They indicate the presence of large numbers of very small nerve fibers, with a modal diameter of about 0.2 µ and a narrow range for their size variation. From one side of the nasal septum of a pig the yield of fibers was estimated at 6,000,000; the number arising from the turbinates would be considerably larger. The fibers are attached to the membranes of the Schwann sheaths in large bundles through mesaxons longer and more branched than those that have been seen in other nerves.
Continuity of the axons between the nerves and the bipolar cells was traced in an examination of the olfactory mucous membrane; and the indication of a one-to-one relationship between cells and axons was reinforced by a comparative count. After the axons leave the bipolar cells they become incased in the central projections of the sustentacular cells. Where the latter come into contact with the basal cells the axons emerge to push back the plasma membranes of the basal cells in the first step in acquiring their nerve sheaths. Later steps are described. When the axons are delivered by the basal cells to the collecting Schwann tubes, they are already aggregated into small bundles with sheaths fundamentally the same as those they will possess until they are delivered to the glia in the olfactory bulb.
Some of the aspects of the cytology of the bipolar cells and adjoining sustentacular cells are described.
A survey of the physiological properties of olfactory nerve fibers was made in some experiments on the olfactory nerve of the pike. Almost all of the action potential is encompassed within a single elevation, manifesting at its front a conduction velocity of 0.2 m./sec. For a comparison, the last elevation in the C action potential in the sciatic nerve of the frog is cited as an example of conduction at the same velocity.
Though expressed through long time constants, the properties of the pike olfactory fibers conform to the generalized schema for properties of vertebrate nerve fibers. This conformity signalizes that they differ from the exceptional properties of the unmedullated fibers of dorsal root origin.
An afferent function for unmedullated nerve fibers does not imply that the fibers concerned are alike in their physiological properties.
PHOTOREVERSAL OF NUCLEAR AND CYTOPLASMIC EFFECTS OF SHORT ULTRAVIOLET RADIATION ON PARAMECIUM CAUDATUM
Authors: Brandt C. L. , Giese A. C. 
Published: May 2004

1. Irradiation with three short ultraviolet (UV) wave lengths, 226, 233, and 239 mµ rapidly immobilizes Paramecium caudatum, the dosage required being smaller the shorter the wave length. 85 per cent of paramecia immobilized with wave length 226 mµ recover completely. Recovery from immobilizing doses is less the longer the wave length.
2. Irradiation continued after immobilization kills the paramecia in a manner which is markedly different for very short (226, 233, and 239 mµ) and longer (267 mµ) wave lengths.
3. An action spectrum for immobilization in P. caudatum was determined for the wave lengths 226, 233, 239, 248, and 267 mµ, and found to resemble the absorption of protein and lipide in the wave length region below 248 mµ. Addition of these data to those of Giese (1945 b) gives an action spectrum resembling the absorption by albumin-like protein.
4. Division of P. caudatum is delayed by doses of wave lengths 226, 233, and 239 mµ which cause immobilization, the longest wave length being most effective.
5. Immobilization at any of the wave lengths tested (226, 233, 239, 248, 267 mµ) is not photoreversible when UV-treated paramecia are concurrently illuminated.
6. Division delay resulting from immobilizing doses of 226, 233, and 239 mµ is photoreversible by exposure to visible light concurrently with the UV.
7. Division delay induced by exposure to wave length 267 mµ is reduced by exposure to visible light applied concurrently with UV or immediately afterwards.
8. The data suggest that the shortest UV wave length tested (226 mµ) affects the cytoplasm selectively, because it is absorbed superficially as indicated by unilateral fluorescence in UV. Consequently it immobilizes paramecia rapidly but has little effect on the division rate because little radiation reaches the nucleus.
9. The data support the view that nuclear effects of UV are readily photoreversed but cytoplasmic effects are not.
COMPARATIVE HYDROLYSIS OF GELATIN BY PEPSIN, TRYPSIN, ACID, AND ALKALI
Authors: Northrop John H. 
Published: May 2004

A comparison has been made of the relative velocity of hydrolysis of the various peptid linkings of the gelatin molecule when hydrolyzed by acid, alkali, pepsin or trypsin. It has been found that:
1. Those linkages which are most rapidly split by pepsin or trypsin are among the more resistant to acid hydrolysis.
2. Those linkages which are hydrolyzed by pepsin are also hydrolyzed by trypsin.
3. Trypsin hydrolyzes linkages which are not attacked by pepsin.
4. Of the linkages which are hydrolyzed by both enzymes, those which are most rapidly hydrolyzed by pepsin are only slowly attacked by trypsin.
5. Those linkages which are attacked by trypsin or pepsin are among the ones first (most rapidly) hydrolyzed by alkali.
In general it may be said that the course of the early stages of hydrolysis of gelatin is similar with alkali, trypsin, or pepsin and quite different with acid.
THE NATURE OF FOVEAL DARK ADAPTATION
Authors: Hecht Selig 
Published: May 2004

1. After a discussion of the sources of error involved in the study of dark adaptation, an apparatus and a procedure are described which avoid these errors. The method includes a control of the initial light adaptation, a record of the exact beginning of dark adaptation, and an accurate means of measuring the threshold of the fovea after different intervals in the dark.
2. The results show that dark adaptation of the eye as measured by foveal vision proceeds at a very precipitous rate during the first few seconds, that most of the adaptation takes place during the first 30 seconds, and that the process practically ceases after 10 minutes. These findings explain much of the irregularity of the older data.
3. The changes which correspond to those in the fovea alone are secured by correcting the above results in terms of the movements of the pupil during dark adaptation.
4. On the assumption that the photochemical effect of the light is a linear function of the intensity, it is shown that the dark adaptation of the fovea itself follows the course of a bimolecular reaction. This is interpreted to mean that there are two photolytic products in the fovea; that they are disappearing because they are recombining to form anew the photosensitive substance of the fovea; and that the concentration of these products of photolysis in the sense cell must be increased by a definite fraction in order to produce a visual effect.
5. It is then suggested that the basis of the initial event in foveal light perception is some mechanism that involves a reversible photochemical reaction of which the "dark" reaction is bimolecular. Dark adaptation follows the "dark" reaction; sensory equilibrium is represented by the stationary state; and light adaptation by the shifting of the stationary state to a fresh point of equilibrium toward the "dark" side of the reaction.
THE SELECTIVE ABSORPTION OF POTASSIUM BY ANIMAL CELLS
Authors: Mitchell Philip H. , Wilson J. Walter , Stanton Ralph E. 
Published: May 2004

1. Frog muscles perfused with Ringer solution in which potassium chloride has been replaced by an equivalent amount of rubidium or cesium chloride take up rubidium or cesium and incorporate them into the tissue substance in such form as to be retained during a subsequent perfusion with potassium-free Ringer solution, provided the muscles contract during the first perfusion. Retention of rubidium or cesium by a resting muscle does not occur.
2. Rats on synthetic diets, adequate in all respects except that potassium was replaced by an equivalent amount of rubidium or cesium, died after a period varying from 10 to 17 days with characteristic symptoms including tetanic spasms. Muscle, heart, liver, kidney, spleen, and lung tissues were then found to contain significant amounts of rubidium or cesium. The concentration of these metals in the muscle amounted, in some cases, as shown by a spectroscopic estimation, to about half the concentration of potassium normally found in mammallian muscle.
3. The results are regarded as tending to confirm the theory that the peculiarities in the physiological effects of potassium, including the facility with which it is "selected" by living cells in preference to sodium, are related to the electronic structure of the potassium ion as compared with that of similar ions. The possible relationship of the comparative migration velocity, a function of the electronic structure, to physiological effects is suggested.
DIRECT AND INDIRECT DETERMINATIONS OF PERMEABILITY
Authors: Osterhout W. J. V. 
Published: May 2004

1. Methods are described for obtaining cell sap from Nitella without contamination.
2. Tests of the cell sap show that in a balanced solution of NaNO3 plus Ca(NO3)2 there is a slow penetration of NO3 and that the cell remains in a normal condition, but in pure NaNO3 there is rapid penetration accompanied by injury.
3. Inasmuch as determinations of electrical conductivity give the same result it may be concluded that this method gives reliable information regarding permeability.
4. While observations on recovery from plasmolysis give similar results, the method is less satisfactory.
THE ORIGIN OF THE ELECTRICAL CHARGES OF COLLOIDAL PARTICLES AND OF LIVING TISSUES
Authors: Loeb Jacques 
Published: May 2004

1. When a solution of a salt of gelatin or crystalline egg albumin is separated by a collodion membrane from a watery solution (free from protein) a potential difference is set up across the membrane in which the protein is positively charged in the case of protein-acid salts and in which the protein is negatively charged in the case of metal proteinates. The turning point is the isoelectric point of the protein.
2. Measurements of the pH of the (inside) protein solution and of the outside watery solution show that when equilibrium is established the value pH inside minus pH outside is positive in the case of protein-acid salts and negative in the case of metal proteinates. This is to be expected when the P.D. is caused by the establishment of a Donnan equilibrium, since in that case the pH should be lower outside than inside in the case of a protein-acid salt and should be higher outside than inside in the case of a metal proteinate.
3. At the isoelectric point where the electrical charge is zero the value of pH inside minus pH outside becomes also zero.
4. It is shown that a P.D. is established between suspended particles of powdered gelatin and the surrounding watery solution and that the sign of charge of the particles is positive when they contain gelatin-acid salts, while it is negative when the powdered particles contain metal gelatinate. At the isoelectric point the charge is zero.
5. Measurements of the pH inside the powdered particles and of the pH in the outside watery solution show that when equilibrium is established the value pH inside minus pH outside is positive when the powdered particles contain a gelatin-acid salt, while the value pH inside minus pH outside is negative when the powdered particles contain Na gelatinate. At the isoelectric point the value pH inside minus pH outside is zero.
6. The addition of neutral salts depresses the electrical charge of the powdered particles of protein-acid salts. It is shown that the addition of salts to a suspension of powdered particles of gelatin chloride also diminishes the value of pH inside minus pH outside.
7. The agreement between the values 58 (pH inside minus pH outside) and the P. D. observed by the Compton electrometer is not only qualitative but quantitative. This proves that the difference in the concentration of acid (or alkali, as the case may be) in the two phases is the only cause for the observed P.D.
8. The Donnan theory demands that the P.D. of a gelatin chloride solution should be 1½ times as great as the P.D. of a gelatin sulfate solution of the same pH and the same concentration (1 per cent) of originally isoelectric gelatin. This is found to be correct and it is also shown that the values of pH inside minus pH outside for the two solutions possess the ratio of 3:2.
9. All these measurements prove that the electrical charges of suspended particles of protein are determined exclusively by the Donnan equilibrium.
CHANGE OF ACID AGGLUTINATION OPTIMUM AS INDEX OF BACTERIAL MUTATION
Authors: De Kruif Paul H. 
Published: May 2004

A distinct difference in acid agglutination optimum for Type D (bacillus of rabbit septicemia) and its mutant form, Type G, has been observed. The optimum for Type D lies between pH 3.5 and pH 3.0. This changes during mutation, the resulting Type G mutants having in general an optimum lying between pH 4.7 and pH 3.8.
The constancy of the optimum for Type D is very strict, while that for Type G is slightly less so. The variation is never so great as to cause an overlapping of optima and consequent failure of differentiation.
These acid agglutination optima are in the nature of physical constants for the two types and would imply a fundamental difference in the chemical constitution of the organisms.
Animal passage, far from causing a reversion of the mutant Type G to the primordial Type D form, brings about a still greater instability in the presence of H ions.
BANANA GEL
Authors: McGuire Grace , Falk K. George 
Published: May 2004

The conditions for the formation of gels from banana extracts were studied.
Gels were obtained with extracts more alkaline than pH 7.0 with very small quantities of calcium, strontium, and barium salts, the gel formation with these salts decreasing in the indicated order.
In solutions more acid than pH 6.0, no gels were obtained with these salts.
Magnesium, lithium, and sodium salts did not cause gel formation either in acid or alkaline solutions.
Pancreatine gave a gel on incubation with banana extract at pH 5.0.
The gel-forming property of banana extracts was destroyed on boiling.
QUANTITATIVE LAWS IN REGENERATION
Authors: Loeb Jacques 
Published: May 2004

It is well known that a long defoliated piece of stem of Bryophyllum calycinum forms shoots only at the apical or the two apical nodes, while when such a stem is cut into as many pieces as there are nodes each node produces shoots. It is shown in this paper that the dry weight of shoots produced in the apical nodes of a long piece of stem is approximately equal to the dry weight of shoots the same stem would have produced if it had been cut into as many pieces as it possesses nodes. Hence all the material which can be used for the growth of shoots goes into the most apical part of the stem and this accounts for the polar character of regeneration in this case.
It seems that the mass of basal roots produced by a piece of defoliated stem also increases with the mass of the stem.