bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE ROLE OF SULFHYDRYL GROUPS IN THE BLEACHING AND SYNTHESIS OF RHODOPSIN
Authors: Wald George , Brown Paul K. 
Published: May 2004

The condensation of retinene1 with opsin to form rhodopsin is optimal at pH about 6, a pH which favors the condensation of retinene1 with sulfhydryl rather than with amino groups. The synthesis of rhodopsin, though unaffected by the less powerful sulfhydryl reagents, monoiodoacetic acid and its amide, is inhibited completely by p-chloromercuribenzoate (PCMB). This inhibition is reversed in part by the addition of glutathione. PCMB does not attack rhodopsin itself, nor does it react with retinene1. Its action in this system is confined to the —SH groups of opsin. Under some conditions the synthesis of rhodopsin is aided by the presence of such a sulfhydryl compound as glutathione, which helps to keep the —SH groups of opsin free and reduced.
By means of the amperometric silver titration of Kolthoff and Harris, it is shown that sulfhydryl groups are liberated in the bleaching of rhodopsin, two such groups for each retinene1 molecule that appears. This is true equally of rhodopsin from the retinas of cattle, frogs) and squid.
The exposure of new sulfhydryl groups adds an important element to the growing evidence that relates the bleaching of rhodopsin to protein denaturation. The place of sulfhydryl groups in the structure of rhodopsin is still uncertain. They may be concerned directly in binding the chromophore to opsin; or alternatively they may furnish hydrogen atoms for some reductive change by which the chromophore is formed from retinene1.
In the amperometric silver titration, the bleaching of rhodopsin yields directly an electrical variation. This phenomenon may have some fundamental connection with the role of rhodopsin in visual excitation, and may provide a model of the excitation process in general.
EFFECT OF POTASSIUM DEFICIENCY ON CARBON DIOXIDE, CATION, AND PHOSPHATE CONTENT OF MUSCLE
Authors: Gardner Lytt I. , MacLachlan Elsie A. , Berman Helen 
Published: May 2004

Albino rats weighing 160 to 175 gm. were fed a complete synthetic diet containing 0.003 per cent potassium and 0.7 per cent sodium for 40 days. Controls were given the same diet plus adequate added potassium.
1. Data from analyses of serum and skeletal muscle showed (a) a fall in serum chloride concentration and an increase in serum carbon dioxide concentration and pH in the potassium-deficient rats; (b) increases of sodium, magnesium, and calcium and a decrease of potassium in the muscle of the potassium-deficient rats; (c) no change of muscle chloride or carbon dioxide concentrations in the potassium-deficient rats.
(2) Application of the Wallace-Hastings calculations to these data revealed (a) intracellular pH of the skeletal muscle of the normal rat to be 6.98 ± 0.08; (b) an increase in serum partial pressure of carbon dioxide (pCO2) in potassium deficiency, together with increases in concentrations of [H2CO2] and [HCO3-] per kg. extracellular water and [H2CO3] per kg. cell water; (c) a decrease in values for [CO2] and [HCO3-] per kg. intracellular water; (d) a fall of intracellular pH in potassium deficiency to 6.42 ± 0.05.
(3) Analyses of sacrospinalis muscle from five men undergoing operation for ruptured intervertebral disc showed a mean value of 9.46 ± 1.31 mM carbon dioxide per kg. blood-free tissue.
Some problems of interpretation of data are briefly discussed.
UPTAKE OF GLYCINE-N15 BY COMPONENTS OF CELL NUCLEI
Authors: Daly Marie M. , Allfrey V. G. , Mirsky A. E. 
Published: May 2004

1. The uptake of glycine-N15 by components of cell nuclei was studied. The nuclear components were derived both from tissues with high metabolic rates-mammalian liver, kidney, and pancreas-and from cells with relatively low rates of metabolism-avian erythrocytes and echinoderm sperm. N15 uptake by nuclear components of liver, kidney, and pancreas was far more rapid than by those of erythrocytes and sperm.
2. The nuclear components of liver, kidney, and pancreas for which measurements were made were DNA, histone, and residual protein of chromatin. Uptake into DNA was low, into histone higher, and into residual protein much higher still, being comparable with that into mixed cytoplasmic protein.
3. A comparison of the uptake of N15 by the chromosomal components, histone and DNA of liver, pancreas, and kidney showed that chromosomal "activity" varies in different cells and also in the same cell depending upon its over-all activity.
FORMATION OF PROTEIN IN THE PANCREAS
Authors: Daly Marie M. , Mirsky A. E. 
Published: May 2004

1. The total known secretory enzyme content of the mouse pancreas has been determined and found to represent about 20 per cent of the weight of the dry, fat-free tissue.
2. The changes in secretory enzyme content that occur during the cycle of secretion and synthesis have been measured.
3. In the course of the cycle no significant changes have been found in DNA or RNA content of pancreatic tissue.
4. Constancy of DNA content, along with other observations, indicates that total protein content of the gland remains substantially unchanged during the cycle of secretion and synthesis. These facts point to the conclusion that following upon the secretion of enzyme protein, synthesis of new protein takes place relatively rapidly in the exocrine cells of the pancreas and this protein is then gradually transformed into the characteristic pancreatic enzyme proteins.
OXYGEN DISSOCIATION OF WHOLE BLOOD STUDIED POLAROGRAPHICALLY
Authors: Markus Gabor , Baumberger J. Percy 
Published: May 2004

The polarographic current of whole blood is in excess of that given by plasma at the same oxygen tension. The magnitude of this difference depends on (a) the oxygen content of the sample and thus is determined by the red blood cell content and by the state of oxygen saturation of hemoglobin, and (b) on the rate of dissociation of oxyhemoglobin and therefore is influenced by changes in pH, pCO2, and temperature.
The total current at 37°C. is proportional to the oxygen content of the sample and can be used to determine the latter.
The theoretical basis of the studied phenomena is discussed in detail.
AN ANALYTICAL STUDY OF IN VIVO SURVIVAL OF LIMITED POPULATIONS OF ANIMAL RED BLOOD CELLS TAGGED WITH RADIOIRON
Authors: Brown I. W. , Eadie G. S. 
Published: May 2004

Animal red blood cell in vivo survival curves, obtained by the radioiron tagging of populations of approximately the same age followed by the administration of non-radioactive iron to suppress radioiron reutilization, have been subjected to mathematical analysis on the basis of the three following assumptions:—
(A) Red blood cells disappear from the circulation as the result of senescence: there is an average life span around which the life spans of individual cells are distributed in the usual way.
(B) Red blood cells may be removed from the circulation by a process of random destruction which continuously removes a constant fraction of the cells present at any moment irrespective of age or other characteristics.
(C) Under the conditions of the experiments described, a fraction of the radioiron, constant for each animal, is reutilized in new red cell formation when released by red cell destruction.
This mathematical analysis indicates the following average life spans with the respective standard errors of the mean: dog 107 days ± 1.14; rabbit 67.6 days ± 1.94; cat 68.4 ± 1.50.
The mathematical treatment presented has permitted a consideration of the theoretical variation of red cell life spans which was found in these experiments to be relatively small for all three species studied. In the rabbit and cat 2.5 per cent of tagged populations of red cells of the same age would theoretically have disappeared by senescence 17 days before the average life span was reached. The variation of red cell life in the dog was slightly less.
Animals of the three species studied, in spite of apparently normal health, exhibited varying degrees of random destruction of both autogenous and transfused fresh normal homologous red cells. As yet, we have no explanation for this random loss of cells occurring in apparently healthy normal animals.
The method of mathematical analysis presented is applicable to animal red cell survival studies employing radioiron in which differing rates of random destruction are operating in the removal of red cells.
IMMUNOLOGICAL STUDIES OF INSECT METAMORPHOSIS
Authors: Telfer William H. , Williams Carroll M. 
Published: May 2004

1. The cell-free blood of the Cecropia silkworm produces a maximum of nine bands of antigen-antibody precipitate when reacted in antiserum-agar tests with antisera prepared by injecting Cecropia extracts into rabbits. The blood antigens producing these bands of precipitate have the properties of proteins in that they are non-dialyzable, labile at 75°C., and salted out by 75 per cent saturated ammonium sulfate. One antigen was identified as a carotenoid protein.
2. Six bands of precipitate were selected for further study. Absorption tests revealed that the blood, at all stages of metamorphosis, is capable of precipitating the antibodies which produce five of these bands. This result indicates that five of the six antigens are present in the blood throughout metamorphosis. The sixth antigen is undetectable in blood from fourth instar larvae, appears in the blood late in the fifth instar, persists during the pupal stage, and disappears again during adult development.
3. When blood samples from various stages of metamorphosis were tested in antiserum-agar tubes, the rates of advance of the six bands of precipitate underwent systematic change in close correlation with the morphological stage of the silkworm's metamorphosis. These changes are interpreted in terms of concentration changes of the corresponding blood antigens. The validity of this interpretation was tested in several ways, with the conclusion that the interpretation was generally acceptable for the system under consideration.
4. All six antigens appear to increase in concentration during the last larval instar and to decrease in concentration during the period of adult development. However, each antigen has its own characteristic pattern of concentration change which differs from those of the other five. In order to explain this diversity, we conclude that the physiological mechanisms which regulate the synthesis and utilization of the blood antigens control each antigen on an individual basis.
THE MOTILITY OF RAM AND BULL SPERMATOZOA IN DILUTE SUSPENSION
Authors: Blackshaw A. W. 
Published: May 2004

1. Ram and bull spermatozoa suspended in a glucose-sodium chloride solution rapidly lose motility at relatively high dilutions. The substitution of chloride-free diluents does not alter the phenomenon.
2. The rapid immobilization of ram and bull spermatozoa due to high dilution may be partially prevented by the addition of supernatants of either ram or bull semen, although motility is not maintained at the same level as in a more concentrated specimen. Various other substances which also partially protect spermatozoa are egg albumin, plasma albumin, plasma gamma globulin, starch, and glycogen.
3. Washing ram spermatozoa six times greatly reduces motility. This is not restored by the addition of ram seminal plasma which, however, reverses the concurrent head agglutination.
4. Washing ram and bull spermatozoa four times results in considerable loss of motility and head agglutination both of which may be reversed by the addition of seminal plasma.
5. Potassium chloride at 0.005 M concentration partially restores the motility of four times washed ram spermatozoa at 24°C. or 37°C. but not that of similarly treated bull spermatozoa.
FLUORESCEIN-CONJUGATED BOVINE ALBUMIN
Authors: Schiller Alfred A. , Schayer Richard W. , Hess E. L. 
Published: May 2004

Fluorescein-bovine albumin conjugates have been prepared and found not to differ appreciably in size, shape, and homogeneity from the precursor, bovine serum albumin. Fluorescein has also been conjugated to rat plasma proteins.
Their disappearance rates from the circulation of rats correspond with those obtained from the use of isotope labeling.
Their sites of localization in rat tissues were shown to be in the cytoplasm but not in the nuclei of Kupffer cells, fixed macrophages, granulocytes, and proximal renal tubules. Adsorption to endothelium was a characteristic finding. Extracellular localizations were predominantly in the lumina of blood vessels and proximal renal tubules (but never in the lumina of collecting tubules), and the interstitial fluid of skeletal and cardiac muscle (but not that of glandular organs such as the adrenals, liver, and spleen).
BAC absorption from the skin of rabbits requires days whereas sodium fluorescein absorption is measured in hours, attesting to the persistence of the colloidal state of BAC in vivo.
Fluorescein conjugates have been used to visualize the transcapillary passage of circulating proteins in the mesenteric circulation of frogs and rats by direct microscopic observation and found to diffuse slowly in the manner predicted for plasma proteins.
The normal cutaneous vessels of the rat are impermeable in the gross to the labeled proteins; second degree burn promptly increases the permeability of these vessels rendering the presence of the label detectable in the gross in the skin.
The process of labeling does not render guinea pig albumin antigenic, although slight antigenicity results from labeling whole plasma protein.
It is believed that sufficient biological evidence is presented to support the conclusion that fluorescein-conjugated plasma proteins, particularly albumin, behave in vivo like their native precursors.
THE SPECIFIC HEAT OF RED CELLS, WITH SPECIAL REFERENCE TO THE PARACRYSTALLINE RAT RED CELL
Authors: Ponder Eric 
Published: May 2004

The specific heat of the rat red cell, kept in cold sodium citrate, changes in the neighborhood of 6°C., the temperature near which the cell passes from its paracrystalline state to a state of greater disorder. The change in the specific heat is from 0.74 with a standard deviation of ±0.022 (paracrystalline state) to 0.87 with a standard deviation of ±0.021 (normal state).
Although it has been looked for, no evidence of a change in specific heat has been found, between 1°C. and 15°C., in the case of the human red cell or of the fresh rat red cell in saline or plasma.
EFFECT OF HELIUM ON THE RESPIRATION AND GLYCOLYSIS OF MOUSE LIVER SLICES
Authors: South Frank E. , Cook Sherburne F. 
Published: May 2004

It has been shown that helium has the ability to affect variously the rates of certain metabolic reactions in vitro as compared to nitrogen. An attempt has been made to approximate the sites of action in mouse liver preparations.
The following results have been obtained by the substitution of a mixture of 80 per cent helium and 20 per cent oxygen for air: (a) An increase in the rate of oxygen consumption and carbon dioxide production to the same degree, the respiratory quotient remaining unchanged. (b) A decrease in the magnitude of cyanide inhibition. The effectiveness of helium increases with the degree of the cyanide inhibition. (c) No effect on the activity of slices which have been poisoned with fluoride when either lactate or pyruvate has been added as a substrate. (d) A change in the rate, and the slope of the curve of oxygen consumption in liver homogenates which are utilizing pyruvate as a substrate.
The use of helium relative to nitrogen under anaerobic conditions causes: (a) A depression of the glycolytic rates in both mouse liver slices and diaphragm. (b) An increase in the carbon dioxide evolution and lactic acid production of mouse liver homogenates oxidizing either glucose and hexose diphosphate, or hexose diphosphate alone.
In neither slices nor homogenates does the addition of fluoride and the use of pyruvate as the hydrogen acceptor alter the fundamental response of the preparations.
The following hypotheses have been advanced and discussed in order to explain the observed phenomena:
1. Helium does not alter the substrate utilized by the tissue.
2. The gas interferes in some way with the cyanide-cytochrome oxidase bond, but may not affect cytochrome oxidase in the absence of cyanide.
3. The citric acid cycle is not subject to the influence of helium in tissue slices, but is altered in an unexplained fashion in homogenates. It is postulated that a rearrangement of particulate surfaces may be the significant factor here.
4. The glycolytic cycle is the site of both an inhibitory and an acceleratory effect of helium. The locus of the inhibition lies above the aldolase reaction and that of the acceleration between the aldolase and enolase reactions.
STIMULATION OF GERMINATION AND RESPIRATION OF THE SPORES OF BACILLUS MEGATHERIUM BY MANGANESE AND MONOVALENT ANIONS
Authors: Levinson H. S. , Sevag M. G. 
Published: May 2004

1. The addition of manganese in a concentration as low as 1.8 x 10–5 M stimulates both respiration and germination markedly and eliminates the need for heat activation of spores respiring in inorganic salts-glucose.
2. Rapid germination and respiration of B. megatherium spores require a proper balance of ions in the nutrient medium. The repressive effect of a high phosphate concentration can be eliminated or balanced by chloride, or by other monovalent anions. Adenosine can relieve the necessity for chloride in such a system.
CYTOCHROME OXIDASE ACTIVITY DURING DIAPAUSE AND METAMORPHOSIS OF THE JAPANESE BEETLE (POPILLIA JAPONICA NEWMAN)
Authors: Ludwig Daniel 
Published: May 2004

1. Determinations were made on the activity of cytochrome oxidase of individual Japanese beetles during growth, diapause, and metamorphosis. All readings were made on homogenates at a dilution of 1:1,000, except for adult beetles, when the final dilution was 1:10,000.
2. The activity of the enzyme increased during larval growth from a low value of 0.022 in the second instar, to high values ranging from 0.074 to 0.083 in diapause third instar larvae.
3. The high activity of cytochrome oxidase during larval diapause indicates that this condition may be physiologically different from that occurring in the egg or pupal stages of most other insects.
4. During metamorphosis, the activity of cytochrome oxidase follows the characteristic U-shaped curve associated with respiratory metabolism. It thus appears that most of the oxidation occurring in metamorphosing individuals is mediated through the cytochrome system.
5. The activity of cytochrome oxidase is significantly higher in the adult male than it is in the adult female; the values (calculated on the basis of a 1:1,000 dilution) were 0.40 ± 0.028 and 0.25 ± 0.012, respectively.
VOLUME CHANGES, ION EXCHANGES, AND FRAGILITIES OF HUMAN RED CELLS IN SOLUTIONS OF THE CHLORIDES OF THE ALKALINE EARTHS
Authors: Ponder Eric 
Published: May 2004

1. Concentrations of BaCl2, MgCl2, SrCl2, and CaCl2 can be found in which the volume of washed human red cells remains almost unchanged for short periods of time; in more concentrated solutions the cells shrink, and in less concentrated ones they swell. Between tonicities of about 1.5 and 0.75, the van't Hoff-Mariotte law applies roughly, but at lower tonicities the red cell volume is anomalously great, sometimes in the absence of hemolysis.
2. If the cells are allowed to stand at 4°C. in the media of different tonicities, the volume changes are not maintained. The volumes decrease in a complex way, and the decreases are accompanied by a loss of K from the cells and an entry of the external cation into them.
3. With two exceptions, these ion exchanges are not accompanied by any important changes in the osmotic, mechanical, or heat fragility of the red cells. The exceptions are a marked effect of BaCl2 on heat fragmentation, and of CaCl2 on osmotic and mechanical fragilities.
RELATIONSHIPS BETWEEN TOBACCO MOSAIC VIRUS BIOSYNTHESIS AND THE NITROGEN METABOLISM OF THE HOST
Authors: Commoner Barry , Schieber Dorothy L. , Dietz Phyllis M. 
Published: May 2004

1. Comparisons of the nitrogen content of TMV-infected and uninfected tobacco leaf discs at various times after inoculation show that virus synthesis is associated with a net increase in protein content. This excess protein is due to: (a) TMV, (b) an excess in insoluble protein which develops soon after inoculation and ends about 100 hours before cessation of TMV synthesis, and (c) an excess in soluble non-virus protein, which is variable in size and which only occurs during the time of virus synthesis. A deficiency in non-protein nitrogen occurs during the time when virus appears.
2. Isotope experiments with N15-labelled nutrient show that: (a) The bulk of TMV nitrogen is derived from the free ammonia of the host tissue. (b) Amino acid residues of TMV protein are not derived from the corresponding free amino acids in the host. (c) The appearance of TMV is preceded by the synthesis of an insoluble precursor of the virus which is then converted into TMV or some soluble intermediate protein. This effect is associated with a cell particulate which represents a small fraction of the total insoluble protein. (d) Infected tissue synthesizes de novo small amounts of soluble non-virus protein, which may represent intermediates in TMV synthesis. (e) Infected tissue fails to synthesize a rapidly turned-over soluble protein which is synthesized in comparable uninfected tissue. (f) TMV synthesis is preceded by a temporary enhancement of the metabolic stability of an insoluble protein component.
3. The results lead to the conclusion that TMV formation is due to diversion of some part of the host's protein-synthesizing apparatus from its normal course.
NUCLEIC ACID ECONOMY IN BACTERIA INFECTED WITH BACTERIOPHAGE T2
Authors: Hershey A. D. 
Published: May 2004

1. During the first 10 minutes of viral growth following infection of E. coli by phage T2 in broth, a pool of DNA is built up that contains phosphorus later to be incorporated into phage. This pool receives phosphorus from, but does not contain, the bacterial DNA.
2. After 10 minutes, DNA synthesis and phage maturation keep pace in such a way that the amount of precursor DNA increases moderately for a time and then remains constant.
3. The pool so described is defined in terms of the kinetics of transport of phosphorus from its origins in the culture medium, the bacterial DNA, and the DNA of the parental phage, to the viral progeny. The most interesting parameter of this system is the size of the precursor pool, which measures 10–9 to 2 x 10–9 µg. DNA-P (50 to 100 phage particle equivalents) per bacterium.
4. Neither the precursor nor the intracellular phage population exchanges phosphorus with the phosphate in the medium. More interestingly, the phosphorus in mature phage does not exchange with phosphorus in the precursor, showing that maturation is an irreversible process.
5. Maturation is also a remarkably efficient process. About 90 per cent of labeled phosphorus introduced early into the precursor pool is later incorporated into phage.
6. Viral DNA is synthesized at the rate of about 1.5 x 10–10 µg. DNA-P (7 or 8 phage particles) per bacterium per minute. This is somewhat faster than bacterial DNA is formed, but considerably slower than RNA is formed, in uninfected bacteria.
7. The transport of phosphorus from medium to viral precursor DNA takes an average of 8 or 9 minutes, and from precursor to phage an additional 7 or 8 minutes.
8. Metabolically active RNA has been detected in infected bacteria.