bluuebunny/crossref_metadata_2025_split huggingface dataset:
AGEING AND THE INFLUX OF WATER INTO RADISH ROOT-HAIR CELLS
Authors: Rosene Hilda F. 
Published: May 2004

A micropotometric device previously described by the writer was used to determine quantitatively the velocity of water influx in cubic microns per square micron of hair surface per minute of comparatively older and younger root hairs of radish seedlings in a humid atmosphere at 29° ± 1°C. when the micropotometers were filled with Hoagland solution at pH 6.8. In each experiment, measurements were made on two hairs of different length and different age on a given root and the hairs were inserted into the micropotometers a sufficient distance so that the area of immersion, 13,200µ2, was the same in each instance.
The range of velocities of water influx through the immersed surface was 4.46 to 1.16µ3/µ2/min. for the younger and shorter hairs which varied in length from 280 to 460 microns. The range of velocities of water influx through the immersed surface of the older hairs which varied from 661 to 2300 microns in length was 1.94 to 0.47µ3/µ2/min. The data indicate that water entry slows down in older hairs independent of root length.
Estimations were made of the times to replace hair volumes based upon the mean velocities of water entry of the immersed areas. It was found that the time for the hairs to absorb an amount of water equivalent to their own volumes under the conditions specified was a matter of minutes or less; the range was 0.90 to 8.51 minutes.
ADSORPTION STUDIES IN A SYNTHETIC RUBBER LATEX-OVALBUMIN SYSTEM
Authors: Williams H. B. , Choppin A. R. 
Published: May 2004

1. Adsorption of ovalbumin on the latex surface was in excess of the quantity required to produce coverage of the surface over most of the protein concentrations range which was investigated.
2. "S" shaped isothermals which probably indicated multilayer adsorption were obtained.
3. The quantity of ovalbumin required to produce a constant surface charge density on the latex particle surface was a function of the pH, and a theory of active centers on the latex particles has been suggested.
4. A shift in the isoelectric point from that of native ovalbumin has been observed for the protein when adsorbed on a synthetic latex.
PHAGE FORMATION IN STAPHYLOCOCCUS MUSCAE CULTURES
Authors: Price Winston H. 
Published: May 2004

1. A strain of S. muscae which requires a substance present in certain acid-hydrolyzed proteins (AHPF) for virus liberation when singly infected in Fildes' synthetic medium no longer needs this substance when multiply infected.
2. In the absence of the AHPF under conditions of multiple infection the amount of phage released is approximately equal to the number of infecting particles between two to ten. Over ten particles per cell has no further effect on the yield of virus.
3. The experimental evidence indicates that it is the phage particle and not some other component in the lysate which can replace the AHPF.
4. The minimum latent period and rise period of cells singly infected in the presence of the AHPF and multiply infected in the absence of the AHPF are the same.
5. The desoxynucleic acid synthesis of cells, infected with a very few virus particles in the presence of excess AHPF and multiply infected with ten particles in the absence of the AHPF, occurs at approximately the same rate, with both infected samples synthesizing about the same amount of desoxynucleic acid and liberating the same yields of virus.
6. A strain of S. muscae which requires aspartic acid for virus synthesis when singly infected does not need this substance when multiply infected, the burst size under the latter conditions depending upon the multiplicity of infection between 3 to 12 particles per cell.
7. The data indicate that the virus released from multiply infected cells in the absence of added AHPF or aspartic acid is newly synthesized virus and not the original infecting particles.
8. The phage particle contains the AHPF and aspartic acid.
9. As a tentative working hypothesis, it is assumed that the AHPF and aspartic acid for phage formation under conditions of multiple infection, in the absence of added AHPF, or of aspartic acid, are contributed by the original infecting particles.
10. Ultraviolet-inactivated phage is adsorbed to the host cell and kills the cell although little virus is released under the experimental conditions.
11. Ultraviolet-inactivated phage particles, if added before the active particle is adsorbed, will greatly inhibit the liberation of new virus particles; but does not do so if added a few minutes after the active particle has been adsorbed.
12. Under the experimental conditions, reactivation of phage when present in multiply infected cells does not occur; and such ultraviolet-inactivated phage cannot serve as a source of the AHPF or aspartic acid, although the AHPF can be liberated from such inactivated particles by acid hydrolysis.
13. The results are discussed in relation to Luria's experiments with ultraviolet-treated phage and to his "gene pool" hypothesis of phage formation.
RATE OF EXCRETION OF N15 AFTER FEEDING N15-LABELED l-ASPARTIC ACID IN MAN
Authors: Wu Hsien , Snyderman Selma E. 
Published: May 2004

1. l-Aspartic acid labeled with N15 was fed to one human adult and six infants, and the total N and N15 were determined in the urine from time to time.
2. The N15 concentration (or isotopic ratio) of urinary N reached its maximum in the adult about 2 hours and in the infants about 4 hours after feeding, then fell off logarithmically.
3. Assuming that the N of aspartic acid readily entered into equilibrium with other N compounds in the pool, the rate of turnover of the N pool was calculated from the rate of fall of the isotopic ratio of urinary N. This rate of turnover of N was about 4 per cent per hour in the adult and 6 to 12 per cent per hour in the infants.
4. The rate of protein synthesis calculated from the rate of turnover of N was 10 mg. N per kilo per hour in the adult and 18 to 27 mg. N per kilo per hour in the infants, with one exception which showed a higher rate of 52 mg. N per kilo per hour. The size of the metabolic pool of N per kilo in non-growing infants was about the same as that in the adult (0.4 to 0.5 gm.) but it was somewhat larger in growing infants (0.5 to 0.8 gm.).
THE DESOXYRIBONUCLEIC ACID CONTENT OF ANIMAL CELLS AND ITS EVOLUTIONARY SIGNIFICANCE
Authors: Mirsky A. E. , Ris Hans 
Published: May 2004

1. Evidence is summarized for the constancy of DNA content for each set of chromosomes in the various cells of an organism.
2. The DNA contents of the egg and sperm nuclei are the same.
3. A brief survey is given of DNA contents per cell in invertebrates and vertebrates.
(a) In invertebrates there is some slight evidence that when primitive and higher forms are compared the amount of DNA per cell is increased in the latter.
(b) In fishes there is a tendency for the amount of DNA per cell to remain constant within the different species of a family.
(c) The values of DNA per cell in lung fishes, amphibians, reptiles, and birds suggest that in the evolution of these vertebrates there has been a decline in DNA content per cell.
4. Concerning the significance of quantity of DNA per cell in vertebrates:
(a) It appears not to be in proportion to the number of different genes in a cell.
(b) It may be related to the number of strands in the chromosomes.
(c) In homologous cells of different animals it is directly related to the mass of the cell.
SOME EFFECTS OF 2537 Å ON GREEN ALGAE AND CHLOROPLAST PREPARATIONS
Authors: Holt A. S. , Brooks I. A. , Arnold W. A. 
Published: May 2004

1. The kinetics of the inactivation of photosynthesis by 2537 Å in Chlorella pyrenoidosa and Scenedesmus D1 indicate that, while the destruction process is largely a first order effect, higher order effects also occur, which become evident at low exposures. In agreement with previous observations, endogenous respiration is insensitive to exposures which inactivate photosynthesis.
2. In Scenedesmus D1 a solid dose of ultraviolet has no more effect on the photosynthetic apparatus than a dose of equal total duration interrupted by periods of photosynthesis. Nor is any difference noted if the cells are in a different buffer, e.g. 0.05 M KH2PO4, or carbonate-bicarbonate buffer 9.
3. In C. pyrenoidosa, a solid dose and an interrupted dose cause equal effects on photosynthesis when neutral phosphate buffer is used. If the ultraviolet exposure schedules are identical, equal effects are also noted in cells suspended in buffer 9, and in 0.05 M phosphate (pH 6.2). Solid exposures are, however, much more effective than interrupted exposures, when buffer 9 is used.
4. Oxygen evolution (Hill reaction), photosynthesis, and photoreduction in Scenedesmus D1 are equally sensitive to a given dose of ultraviolet. The mechanism responsible for adaptation to hydrogen metabolism is not more sensitive to ultraviolet than is the photosynthetic mechanism. The O2/H2/CO2 reaction in darkness is less sensitive to ultraviolet than any of the above reactions.
5. Glucose oxidation by C. pyrenoidosa, and colony formation in Scenedesmus D1 are far more sensitive to a given dose of ultraviolet than photosynthesis in these organisms.
6. The photosynthetic apparatus of C. pyrenoidosa is more sensitive to ultraviolet than that of Scenedesmus D1.
7. The Hill reaction in chloroplast fragments is also inactivated by 2537 Å by a first order process. Exposures which inactivate this reaction completely have no effect on polyphenol oxidase, cytochrome oxidase, or catalase in the same chloroplast preparation.
8. After irradiation, the survival of photosynthesis in Scenedesmus D1 and of the Hill reaction in chloroplast fragments are independent of the light intensity used to measure these processes.
9. No significant changes occur in the ultraviolet absorption of chloroplasts after an exposure to 2537 Å, which completely inactivates the Hill reaction.
ACTION OF INHIBITORS AT THE MYONEURAL JUNCTION
Authors: Kirschner L. B. , Stone W. E. 
Published: May 2004

1. A study is presented of the actions of certain inhibitors on the frog rectus abdominis muscle stimulated by acetylcholine.
2. A type of analysis has been developed which provides a reliable criterion for judging whether an inhibitor is competing with acetylcholine for receptors at the myoneural junction or whether acting by a different mechanism.
3. The "curares" are shown to act by competitive inhibition at the myoneural junction, confirming earlier work of others on the mode of action of curare.
4. Atropine acts as an inhibitor at the myoneural junction. The inhibition may be non-competitive or it may be complicated by an additional effect at some point other than the myoneural junction.
5. A possible mechanism for anomalous inhibitor effects is the action of a single compound at more than one locus in the Ach mechanism. Eserine exerts such a dual effect at the end-plate.
6. Some of the available electrical and chemical data have been correlated to make possible a partial explanation of the role of Ach in transmission at the myoneural junction.
SOLUBILITY CHANGES OF PROTEINS IN SEA URCHIN EGGS UPON FERTILIZATION
Authors: Monroy Alberto , Oddo Anna Monroy 
Published: May 2004

The results presented in this paper give evidence of changes in solubility occurring in a protein fraction of the eggs of Arbacia lixula upon fertilization. The electrophoretic analysis indicates that it is only one part of one of the components of the KCl fraction that undergoes the change. However, under some experimental conditions (freezing and thawing of the KCl fraction or extraction of the whole eggs with water at room temperature) a larger portion of the KCl fraction, namely the whole group of components a and b, may be involved and undergoes coagulation. Therefore assuming that the results obtained on the extracts of frozen-dried fertilized eggs do reflect what actually occurs under natural conditions, we must also assume the existence of mechanisms controlling the extent of this change in the living eggs. The fact that in many cases one part or the whole of the sensitive fraction has been found to undergo an increase in solubility may suggest that the process of coagulation discovered by Mirsky is a two-step process. In the first step the sensitive fraction undergoes a change that makes it more soluble and then, when certain conditions are fulfilled, coagulation occurs. An alternative explanation could also be that the coagulated or coagulating fraction is attacked by the proteolytic enzyme that, as shown by Lundblad (1949, 1950), is activated on fertilization. This, however, seems to be less probable, as extraction was always carried out at 0° C. and in as short a time as possible.
However, further experiments are needed to decide whether the coagulation of the sensitive fraction is an actual occurrence under natural conditions. The results obtained with the eggs of Arbacia punctulata may cast some doubt on this assumption.
RESTORATION INDUCED BY CATALASE IN IRRADIATED MICROORGANISMS
Authors: Latarjet Raymond , Caldas Luis Renato ,   With the Technical Assistance of Pierre Morenne and Liliane Chamaillard
Published: May 2004

1. E. coli, strain K-12, and B. megatherium 899, irradiated in strict but still undefined physiological conditions with certain heavy doses of ultraviolet light, are efficiently restored by catalase, which acts on or fixes itself upon the bacteria in a few minutes. This restoration (C. R.), different from photorestoration, is aided by a little visible light.
2. At 37° the restorability lasts for about 2 hours after UV irradiation; the restored cells begin to divide at the same time as the normal survivors.
3. C. R. is not produced after x-irradiation.
4. B. megatherium Mox and E. coli, strain B/r show little C. R.; E. coli strain B shows none. None of these three strains is lysogenic, whereas the two preceding catalase-restorable strains are.
5. Phage production in the system "K-12 infected with T2 phage" is restored by catalase after UV irradiation, whereas phage production in the system "infected B" is not.
6. With K-12, catalase does not prevent the growth of phage and the lysis induced by UV irradiation (Lwoff's phenomenon).
7. Hypotheses are discussed concerning: (a) the chemical nature of this action of catalase; (b) a possible relation between C. R. and lysogenicity of the sensitive bacteria; (c) the consequences of such chemical restorations on the general problem of cell radiosensitivity.
CHANGES IN NON-PROTEIN NITROGEN METABOLISM DURING TOBACCO MOSAIC VIRUS BIOSYNTHESIS
Authors: Commoner Barry , Dietz Phyllis M. 
Published: May 2004

1. Discs cut from tobacco leaf tissue infected with tobacco mosaic virus and cultured in water contain less non-protein nitrogen than comparable uninfected discs during the time at which TMV is formed. This deficiency disappears when virus formation ceases. Discs cultured in nutrient solution form about twice as much TMV as discs cultured in water. The maximum non-protein nitrogen deficiency is comparable in magnitude to the amount of virus synthesized.
2. The largest difference between injected and uninfected tissue occurs in the ammonia content. Smaller, but significant differences in amide content are found. Infected discs cultured in water show no significant differences from control discs in free amino acid content; infected discs cultured in nutrient solution develop a small deficiency in amino acid nitrogen.
3. The general patterns of change in composition of the pool of soluble nitrogen are similar in both infected and uninfected discs.
4. The data indicate that the bulk of the nitrogen incorporated into virus protein is withdrawn from the leaf's pool of soluble nitrogen; virus is formed de novo from ammonia nitrogen and non-nitrogenous carbon sources. The effect of virus infection on host nitrogen metabolism appears to be due to the formation of virus rather than to its presence.
SULFHYDRYL GROUPS AND THE INTERACTION BETWEEN THE HEMES IN HEMOGLOBIN
Authors: Riggs Austen F. 
Published: May 2004

1. Dialysis of a hemoglobin solution against slightly alkaline buffer (pH 8.68) causes a decrease in heme-heme interaction. The value of n in Hill's equation drops from 2.9 to 2.0, while the oxygen affinity increases slightly. Addition of glutathione largely reverses the effects of dialysis (n rises from 2.0 to 2.5 to 2.6).
2. Addition of the sulfhydryl reagent, p-chloromercuribenzoate (1.8 x 10–3 M), results in a large though not complete blocking of heme-heme interaction. The value of n drops from 2.9 to 1.4. This effect is largely reversed with glutathione (n rises to 2.6).
RESPIRATION AND INTENSITY DEPENDENCE OF PHOTOSYNTHESIS IN CHLORELLA
Authors: Brackett Frederick S. , Olson Rodney A. , Crickard Robert G. 
Published: May 2004

1. Respiration changes as a result of illumination.
2. In the absence of glucose or other supply of substrate, respiration decays in the dark showing at least two types—a fast decay in a few minutes and a slow decay lasting hours.
3. Respiratory response to illumination is delayed.
4. Intermittent illumination (in the absence of glucose, etc.) produces a periodic variation in respiration with a delay or phase lag.
5. Periodic variation of respiration may produce a higher average value in the dark than in the light due to the lag and depending upon the period of intermittent illumination.
6. Based upon average respiration values our data confirm the Kok effect.
7. Interpolated values of respiration, however, result in photosynthetic rates which are linearly dependent upon intensity of illumination.
8. Thus the quantum efficiency is found to be independent of intensity, over the wide range of intensities investigated.
METABOLIC FACTORS INFLUENCING THE SODIUM AND POTASSIUM DISTRIBUTION IN ULVA LACTUCA
Authors: Scott George T. , Hayward Hugh R. 
Published: May 2004

1. Methods for the use of the marine green alga, Ulva lactuca, in studies on electrolyte metabolism are described.
2. The effect of illumination and iodoacetate on the potassium and sodium content, as well as the influence of light and running sea water on the iodoacetate effect was investigated. The rate of exchange of cellular potassium ion for K42 under conditions of light and dark at 20 and 30°C. was studied.
3. Ulva maintained in the dark for long periods loses some potassium and gains sodium, both effects being reversed upon illumination. The presence of 0.001 M iodoacetate in the dark causes a marked progressive loss of potassium and gain of sodium, phenomena which do not occur when the alga is illuminated. Evidence for the penetration of the inhibitor into the cell in the presence of light is presented. The iodoacetate effect on potassium and sodium content, once established, can be "washed out" of the alga when the plant is placed in light and running sea water without the inhibitor. Illumination and increased temperature each favor a more rapid exchange of tissue for environmental potassium ion.
4. In the interpretation of these findings it is emphasized that metabolic work, perhaps in the form of ion transports, must be done by the cell to compensate for the continual flow of potassium ion and sodium ion with their respective concentration gradients and thus maintain homeostasis within the cell. Evidence is presented which indicates separate mechanisms for the distribution of sodium and potassium in this organism. It is further suggested that the degradation of phosphoglyceric acid, an important glycolytic and photosynthetic intermediate, or one of the products of its metabolism supplied the energy for these ion transports(s). The role of permeability per se is considered.
AXOPLASMIC PROTEINS OF THE SQUID GIANT NERVE FIBER WITH PARTICULAR REFERENCE TO THE FIBROUS PROTEIN
Authors: Maxfield Myles 
Published: May 2004

1. Axoplasm of squid giant nerve fibers is examined with the ultracentrifuge and electrophoresis apparatus and several distinct components demonstrated.
2. One of these components, a protein called axon filaments, is isolated by fractional extraction followed by differential ultracentrifugation and redissolving in glycine solution. Axon filaments are monodisperse by ultracentrifugation. Their physical chemical properties have been studied.
3. The existence of a reversible transformation of axon filaments into a particle of lower molecular weight and lower asymmetry has been demonstrated.
A STUDY OF THE ACTION OF PHAGOLESSIN A58 ON THE T PHAGES
Authors: Hall Elizabeth A. , Asheshov Igor N. 
Published: May 2004

Phagolessin A58, an antibiotic substance active against a number of bacterial viruses, was studied for activity against the seven T phages. Only three of the seven phages—T1, T3, and T7—proved to be sensitive to the antibiotic. The antibiotic caused a direct, apparently irreversible inactivation of free phage particles.
A study of the properties of the inactivated phage particles showed that the particles retained the ability to kill host cells and to exert mutual exclusion against an unrelated phage after infectivity was lost. There was a progressive loss in these two properties when higher concentrations of antibiotic were used to inactivate the phage. Results with inactivated T3 and T7 revealed that these two properties—the ability to kill host cells and to exclude an unrelated phage—were lost at a different rate. They were, therefore, presumed to be different properties of these particular phage particles.
The inactivation of phage by phagolessin A58 was inhibited by desoxyribose nucleic acid and to a lesser extent by ribose nucleic add. Cytosine, thymine, adenine, guanine, and cysteine failed to inhibit the reaction.
TISSUE CULTURE STUDIES
Authors: Rosenberg Sheldon , Kirk Paul L. 
Published: May 2004

Some of the compounds in the active fraction of ultrafiltrates of chick embryo extract have been identified as taurine, serine, glutamic acid, xanthine, uracil, glucose-6-phosphate, glucose, ferrous iron, and inorganic phosphate.
Based on the identity of these compounds a synthetic replacement for the ultrafilterable portion of chick embryo extract has been devised. There is an additional nutritional requirement that can be met by vitamin B12. Folic acid appears to be beneficial to the system though the requirements of this or any of the above compounds except vitamin B12 remain for future research. The low nitrogen content of the isolated fraction and the synthetic mixture suggests that the main nutrition of chick cells in roller tube cultures is derived from the non-dialyzable portion of the medium.
A COMPARISON OF FIVE EFFECTS OF ULTRAVIOLET LIGHT ON THE ARBACIA EGG
Authors: Blum Harold F. , Cook John S. , Loos Gordon M. 
Published: May 2004

The demonstration of five different effects of ultraviolet radiation on the sea urchin's egg indicates that more than one basic photochemical process goes on there. Photorecovery is observed in only one of these. The need for caution in interpreting such effects is obvious.
Evidence for a different mechanism for the timing of cleavage in eggs activated by ultraviolet radiation as compared to normally fertilized eggs is presented.
The bearing of these studies on survival curves for microorganisms is discussed.
THE IDENTITY OF THE FLUORESCENT AND DELAYED LIGHT EMISSION SPECTRA IN CHLORELLA
Authors: Arnold William , Davidson J. B. 
Published: May 2004

1. The delayed light emission of Chlorella pyrenoidosa over the wave length range 400 to 950 mµ has been investigated.
2. Emission of delayed light is confined to the range 600 to 800 mµ.
3. To the precision with which the low light intensities involved can be measured with the apparatus in these experiments, the emission spectrum of the delayed light is the same as the spectrum of the fluorescent light.
4. Thus the delayed light must come from excited chlorophyll.