bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE CHEMISTRY OF INSECT HEMOLYMPH
Authors: Wyatt G. R. , Loughheed T. C. , Wyatt S. S. 
Published: May 2004

1. Hemolymph was collected for analysis from the silkworm, Bombyx mori, in a series of developmental stages ranging from the second molt to the late pupa. The mean pH of larval hemolymph after collection was found to be 6.45, that of pupal hemolymph, 6.57; in vivo values may be slightly lower. Total dry solids ranged from 5.4 to 10.6 per cent. Total protein ranged from 1.2 to 5.3 per cent, increasing rapidly during the fifth instar.
2. Free amino acids were separated chromatographically and estimated. Of 19 amino acids identified, amounting collectively to 823 to 1497 mg. per 100 ml., glutamine, histidine, and lysine generally occurred in greatest amount. Tryptophan was not detected, and cystine (or cysteine) was found in only one sample. The total free amino acids account for 35 to 55 per cent of the non-protein nitrogen of the plasma.
3. Free sugars, estimated semiquantitatively on chromatograms, comprise glucose, fructose, and sucrose in total amount ranging from about 5 to 40 mg. per 100 ml. Total acid-soluble, ultrafiltrable carbohydrate, estimated as glucose by the anthrone reaction, ranged from 166 to 635 mg. per 100 ml., indicating the presence of low molecular weight sugar derivatives.
4. Inorganic phosphate amounted to 5 to 15 mg. per 100 ml., and acid-soluble organic phosphate to 100 to 200 mg. per 100 ml. The latter fraction includes several substances, of which one was tentatively identified as glucose-6-phosphate and the remainder are as yet unidentified.
5. Single samples of hemolymph were also taken from larvae of the wax moth, Galleria mellonella, and the spruce sawfly, Diprion hercyniae. These contained even higher concentrations of solutes than the silkworm samples, but with a generally similar distribution. The proportions of the free amino acids were different in each species.
THE STABILITY OF RHODOPSIN AND OPSIN
Authors: Radding Charles M. , Wald George 
Published: May 2004

The stability of cattle rhodopsin and of its protein moiety opsin toward acids and alkalies and on aging was determined by two criteria: maintenance of absorption spectrum, and capacity to regenerate after exposure to light.
On storage at 3°C. at pH near neutrality, the absorption spectrum in the visible region may remain unchanged for as long as 6 months; but the regenerability progressively declines, at very different rates in different preparations. The cause of this decline has not been determined. It may involve denaturation at sites other than the retinene-protein bond, which by the evidence of the absorption spectrum remains intact.
Cattle rhodopsin maintains its absorption spectrum at any pH from 3.9–9.6 for at least an hour at 25–27°C. To both sides of this pH range the pigment bleaches, the extinction falling to half in 1 hour at pH 3.3 and 10.5.
The exposure of rhodopsin to light greatly increases the vulnerability of the product (opsin) to acids and bases. Opsin rapidly loses its capacity to regenerate rhodopsin to both sides of the range of pH 5.5–7.0. Half the regenerability is lost within 45 seconds at pH 3.4 and 9.1; and within 1 hour at pH 5 and 8.
INACTIVATION OF BACTERIA BY DECAY OF INCORPORATED RADIOACTIVE PHOSPHORUS
Authors: Fuerst Clarence R. , Stent Gunther S. 
Published: May 2004

Cultures of Escherichia coli will not grow in media containing very high specific activities of radiophosphorus P32, the inhibition of growth being due to the decay of assimilated P32 atoms. Experiments with a differentially labeled thymineless strain of E. coli show that the P32 disintegrations which occur in the bacterial deoxyribonucleic acid, i.e. in the nucleus, are mainly responsible for the inactivation of the cell. The kinetics with which radioactive bacterial populations are inactivated indicate that the function of several nuclei per bacterial cell must be eliminated by P32 decay before the ability to generate a colony is lost. The efficiency with which each P32 disintegration inactivates the nucleus in which it has occurred is calculated to be 0.02 (at –196°), i.e., similar in magnitude to the killing efficiency of P32 decay in bacteriophages.
P32 decay and thymine starvation cooperate in bringing about the death of individuals of the thymineless strain, from which observation it is inferred that "thymineless death" is likewise a nuclear inactivation.
The descendants of a non-radioactive bacterial culture grown for several generations in the presence of P32 and the descendants of a radioactive culture grown in the absence of P32 are inactivated by P32 decay in a manner which indicates that the phosphorus atoms of bacterial nuclei are dispersed among the progeny nuclei in their line of descendance.
THE RESPONSES OF THE PUPIL OF GEKKO GEKKO TO EXTERNAL LIGHT STIMULUS
Authors: Denton E. J. 
Published: May 2004

1. The responses of the pupil of a nocturnal gecko (Gekko gekko) to external light stimulus were studied.
2. The responses of the pupil are determined by light entering the pupil and not by light acting directly on the iris.
3. The responses of the pupil are very uniform in sensitivity including spectral sensitivity for light coming in different directions to the eye.
4. The possible change in area of the pupil is more than 300-fold and probably represents an effort to shield the pure rod retina from saturating light intensities.
5. The pupil continues to contract sharply for changes in external light intensity which give retinal illuminations corresponding to 106 quanta/sec. striking a retinal rod.
6. There is a large degree of spatial summation of the response; circular external light fields subtending 5 and 140° giving the same illumination at the pupil give approximately the same pupil response.
7. The spectral sensitivity curve agrees with the absorption curve of an extracted pigment from a closely related gecko described by Crescitelli in the followig paper. It is similar to the human scotopic curve but its maximum is displaced about 20 to 30 mµ towards the red end of the spectrum. The fall in sensitivity towards the red end of the spectrum is described by the equation
See PDF for Equation
MONOSYNAPTIC REFLEX RESPONSE OF INDIVIDUAL MOTONEURONS AS A FUNCTION OF FREQUENCY
Authors: Lloyd David P. C. 
Published: May 2004

An assemblage of individual motoneurons constituting a synthetic motoneuron pool has been studied from the standpoint of relating monosynaptic reflex responses to frequency of afferent stimulation.
Intensity of low frequency depression is not a simple function of transmitter potentiality.
As frequency of stimulation increases from 3 per minute to 10 per second, low frequency depression increases in magnitude. Between 10 and approximately 60 per second low frequency depression apparently diminishes and subnormality becomes a factor in causing depression. At frequencies above 60 per second temporal summation occurs, but subnormality limits the degree of response attainable by summation.
At low stimulation frequencies rhythm is determined by stimulation frequency. Interruptions of rhythmic firing depend solely upon temporal fluctuation of excitability. At high frequency of stimulation rhythm is determined by subnormality rather than inherent rhythmicity, and excitability fluctuation leads to instability of response rhythm. In short, whatever the stimulation frequency, random excitability fluctuation is the factor disrupting rhythmic response.
Monosynaptic reflex response latency is stable during high frequency stimulation as it is in low frequency stimulation provided a significant extrinsic source of random bombardment is not present. In the presence of powerful random bombardment discharge may become random with respect to monosynaptic afferent excitation provided the latter is feeble. When this occurs it does so equally at low frequency and high frequency. Thus temporal summation is not a necessary factor. There is, then, no remaining evidence to suggest that the agency for temporal summation in the monosynaptic system becomes a transmitting agency in its own right.
MONONUCLEOTIDES OF THE CELL NUCLEUS
Authors: Osawa Syozo , Allfrey V. G. , Mirsky A. E. 
Published: May 2004

1. It has been demonstrated by ion exchange chromatography that the cell nucleus contains mononucleotides of adenine, guanine, cytosine, uracil, together with diphosphopyridine nucleotide, and several uridine diphosphate derivatives; the adenine nucleotides predominating in amount. Nucleotide components in the cell nucleus are in close agreement both quantitatively and qualitatively with those found in the cytoplasm.
2. In calf thymus sucrose nuclei, nucleotide monophosphates can be phosphorylated to the energy-rich triphosphate form without participation of cytoplasmic components. As to the nature of the phosphorylation, it has been shown that there exist certain differences as well as resemblances between nuclei and mitochondria. A distinctive feature of nuclear phosphorylation is that only intranuclear monophosphates seem to be phosphorylated. The process is completely inhibited by cyanide, azide, and dinitrophenol. However, certain reagents which block oxidative phosphorylation of mitochondria, namely dicumarol, Janus green B, methylene blue, and calcium ions, have no effect on phosphorylation within the nucleus.
3. The bulk of mononucleotides is preserved within thymus nuclei after their isolation in sucrose. Nucleotides are surprisingly well retained by nuclei in a sucrose medium whether or not electrolytes are present and in buffers ranging from pH 3 to 10; under all conditions sucrose is required for retention.
4. Dilute acetate in sucrose releases nucleotides from the nucleus below pH 5.1. As to the effective pH of acetate, there is a sharp boundary between pH 5.1 and pH 5.9. At pH 5.9, and above, acetate does not remove nucleotides from the nucleus. The effects of propionate, formate, and monochloroacetate on the nuclei are the same as that of acetate.
5. When nuclei are exposed to a wide variety of conditions a close correlation is found between the retention in the nucleus of nucleotides and of potassium. This suggests that both substances are part of a common complex in the cell nucleus.
6. It has been shown that upon removal of nucleotides and potassium from calf thymus sucrose nuclei by acetate, the ability to incorporate C14-alanine into nuclear protein is greatly impaired.
INTRACELLULAR RECORDING FROM THE GIANT SYNAPSE OF THE SQUID
Authors: Bullock Theodore H. , Hagiwara Susumu 
Published: May 2004

1. Recording with glass micropipette electrodes inserted close to the synaptic region, in the presynaptic and in the postsynaptic fibers of the giant synapse in the stellate ganglion of the squid, has been accomplished.
2. The forms of the spike and of the synaptic potential are very much like those reported earlier (Bullock, 1948) from macroelectrodes. The crest time and the rate of fall are labile and depend on the state of fatigue, though the time of initiation of the postsynaptic potential does not.
3. It is concluded after examination of both intra- and extracellular recordings that there is a real synaptic delay of the order of 1 or 2 milliseconds at 15–20°C.
4. There is sometimes a very small and sometimes no visible deflection in the intracellular postsynaptic record attributable to the presynaptic spike. It is concluded that transmission cannot be electrical.
5. The amplitude of the postsynaptic potential can be controlled over some range by the amplitude of the presynaptic potential.
6. Hyperpolarization of the postsynaptic membrane results in increase in amplitude of spikes up to 200 millivolts, in increase in the membrane potential level at which the spike flares up, but in no considerable change in the amplitude in postsynaptic potential.
7. The postsynaptic potential can add to the late falling phase and the undershoot of an antidromic spike in the postfiber but cannot add to the crest or early part of the falling phase. The earliest part of the antidromic spike during which the postsynaptic potential can add is probably a period of refractoriness to electrical shock by analogy with the properties of the axon.
STUDIES ON THE ELECTRICAL PROPERTIES OF A SINGLE PLANT CELL
Authors: Kishimoto Uichiro 
Published: May 2004

Impedance changes of single plant cells of Nitella flexilis were studied under different environmental conditions.
With the analysis presented changes in resistance of the protoplasmic membrane and of cell sap can be studied independently and simultaneously.
Under "transcellular osmosis," the resistance of the protoplasmic membrane and of the cell sap increase at the part of the cell where water enters, while they decrease where water goes out.
Ethanol of low concentration (below 8 per cent) first decreases and later increases the resistance of the protoplasmic membrane. Concentrated ethanol (over 10 per cent), however, brings about a large decrease in resistance of the protoplasmic membrane. Its time course is not simple, but undulatory changes occur.
When ethanol is applied to one part of the cell, the resistance of the protoplasmic membrane shows a different type of change, which may be attributed to the local osmotic effect of ethanol; injury generally occurs with comparatively low concentration.
Methanol, ethanol, and propanol have almost the same effect upon the cell, while butanol is toxic at the same concentration.
When the cell dies, the resistance of the protoplasmic membrane decreases greatly, while the resistance of the cell sap increases to a level (several hundred kilo ohms or more), expected when external solution and cell sap are freely mixed with each other.
LACTIC AND α-GLYCEROPHOSPHATE DEHYDROGENASES IN INSECTS
Authors: Zebe E. C. , McShan W. H. 
Published: May 2004

Different tissues, especially muscles, from insects belonging to various groups were extracted and studied for their lactic dehydrogenase (LDH) and α-glycerophosphate dehydrogenase (GDH I) activities from the comparative point of view.
In all cases assays of flight muscle extracts showed extremely low values of LDH activity whereas the GDH activities were surprisingly high. The activities in leg muscles were generally lower. In some insects, however, a very active LDH was found; in these cases the GDH activity seemed to be decreased.
GDH I was rather active in the fat bodies.
The presence of particulate glycerophosphate dehydrogenase (GDH II) was also demonstrated in insect muscles.
These results were interpreted as indicating a system by which there is accomplished immediate and direct breakdown of metabolites to supply large amounts of energy during flight and other activities without the accumulation of intermediate substances.
THE STATISTICAL DETECTION OF THRESHOLD SIGNALS IN THE RETINA
Authors: Fitzhugh Richard 
Published: May 2004

1. Photographic records of impulses from single ganglion cells in the cat's retina were made while the retina was stimulated by flashes occurring once a second. Ten flashes at each of several intensities near threshold were used.
2. For the purpose of statistical analysis, the number of impulses (x) falling within a critical period following each flash was used as an index of the response. Histograms of x were plotted and used to calculate rates of transfer of information by the ganglion cell for the case of an ideal experiment, the yes-no choice, in which flashes of intensity I and blanks are to be distinguished.
3. The information rate increased (a) with increasing stimulus intensity and (b) with the number of identical flashes or blanks presented successively in a block. The intensity chosen as threshold by the experimenter, who observed the impulses visually and aurally, corresponded to an average information rate for single flashes of 0.7 bit/flash, compared to the maximum possible rate of 1 bit/flash. A threshold intensity giving 0.4 or more bit/flash, if presented in blocks of six identical flashes, corresponded to 0.95 or more bit/block, or near certainty. Thus the calculation of information rates using the index x provides an estimate of threshold at least as sensitive as those obtained during an experiment, which were made only after observing the responses to five to ten flashes of the same intensity.
4. The index x has statistical properties similar to those of the "index of neural activity" used by Tanner and Swets (1954) in their statistical model of human vision, and represents a possible physical interpretation of their index. However, x gave values (0.5 to 1.5) of the parameter called the slope which were consistently smaller than their values (2.1 to 3.1).
A MODEL OF GROWTH AND GROWTH CONTROL IN MATHEMATICAL TERMS
Authors: Weiss Paul , Kavanau J. Lee 
Published: May 2004

A practicable model of the growth process, which gives better definition to the problem of growth and growth regulation and greater precision to related experimental work than do earlier models, is developed on the basis of the following assumptions: "Growth" is the net balance of mass produced and retained over mass destroyed and otherwise lost, implying continual metabolic degradation and replacement. Terminal size represents stationary equilibrium between incremental and decremental components. The mass of an organic system consists of two functionally different components,—generative and differentiated. Generative mass increases by the catalytic action of key compounds ("templates") characteristic of each cell type. Each cell also produces specific freely diffusible compounds antagonistic to these templates ("antitemplates"). Growth regulation occurs automatically by a negative "feedback" in which increasing numbers of antitemplates progressively block the corresponding templates.
Differential equations expressing these interrelationships are formulated, integrated, and the solutions evaluated for the case of chick growth. These specific solutions lead to descriptions of the normal growth of a biological system which are in good agreement with known facts, and to predictions of the course of automatic growth regulations after experimental or pathological disturbances which reproduce adequately biological observations in this domain.
THE PROPORTION OF TERRAMYCIN-RESISTANT MUTANTS IN B. MEGATHERIUM CULTURES
Authors: Northrop John H. ,   With the Technical Assistance of Marie King
Published: May 2004

The number of terramycin-resistant mutants in Bacillus megatherium cultures, their mutation rate, and the growth rate of the wild and mutant cells have been determined under various conditions. These values are in agreement with the following equations (Northrop and Kunitz, 1957):—
See PDF for Equation
λ = mutation rate, A = growth rate constant of wild cells,
B = growth rate constant of mutants,
See PDF for Equation
equilibrium. The value of the mutation rate as determined from equation (6) agrees with that found by the null fraction method.
STUDIES ON STREPTOCOCCUS PYOGENES
Authors: Slade Hutton D. 
Published: May 2004

Electron microscopic observations of Streptococcus pyogenes (strain S43, type 6) treated with trypsin and cetyltrimethylammonium bromide (Cetab) are presented. The concentration of trypsin necessary to remove the M protein antigen was shown to bring about a partial digestion of the cells. The cell protoplasm and protoplasmic membrane were affected. No microscopic changes appeared in the cell wall. Cetab did not alter the appearance of the cells.
Both trypsin and detergent altered the permeability of the cell so that citrulline and carbamylphosphate were metabolized. Cells exhibiting enzyme activity on these substrates after Cetab treatment were characterized by the release of lysine, glutamic acid, nucleic acid, and other cellular material.
Enzymes responsible for the metabolism of arginine, citrulline, and carbamylphosphate were shown to reside in the cell protoplasm. Cells which had lost their viability after Cetab treatment still possessed the ability to utilize the latter substrates. Under similar conditions the metabolism of glucose did not occur.
Normal cells were shown to possess the ability to fluoresce in the presence of a dye. The intensity of the fluorescence was reduced by trypsin treatment.
UPHILL TRANSPORT INDUCED BY COUNTERFLOW
Authors: Rosenberg Thomas , Wilbrandt W. 
Published: May 2004

1. In a membrane transport system containing a mobile carrier with affinities for two substrates a concentration gradient with respect to one of the substrates under certain conditions is able to induce an "uphill" transport (against the concentration gradient) of the other.
2. In a kinetic treatment quantitative conditions for such a "flow-induced uphill transport" and some of its characteristics are derived.
3. Experimentally the uphill transport of labelled glucose induced by a concentration gradient for mannose or unlabelled glucose is demonstrated in the human red cell.
4. It is shown that the flow-induced uphill transport is a feature characteristic for mobile carrier systems only and is not to be expected in systems in which the substrate is bound to a fixed membrane component ("adsorption membrane"), although such a system may yield identical transport kinetics. Also with respect to Ussing's flux ratio the two systems are different, the adsorption membrane meeting Ussing's criterion, the carrier membrane not.
5. It is concluded that the transport system in the human red cells must contain a mobile carrier, identical for glucose and mannose.
ELECTROOSMOSIS IN NITELLA
Authors: Blinks L. R. , Airth R. L. 
Published: May 2004

The role of electroosmosis was studied directly in Nitella. The cells were mounted in a water-tight barrier between two chambers containing reversible electrodes for the application of potentials, and fitted with calibrated capillaries to measure water movement.
No water movement was found when small existing bioelectric potentials were short-circuited through an external connection, nor when external potentials up to 1 or 2 volts were applied (producing currents up to 5 µa).
Higher potentials (up to 10 volts) caused small movements of water, toward the negative pole. Larger and often irreversible water movements were produced by potentials up to 20 volts—sometimes persisting after current flow.
A variety of evidence suggests that the effects are caused by injury at the cathodal end of the cell, allowing water to be attracted osmotically at the intact end and forced out at the injured end (transosmosis). This injury is reversible under small applied potentials, irreversible after large ones (100 to 200 times the natural bioelectric values).
Such water flows persist in low salt concentrations (up to 0.09 M NaCl) but almost completely vanish in isotonic (0.26 M) mannitol. This confirms the osmotic, rather than the electroosmotic nature of the water movement. It is estimated that electroosmosis cannot account for more than 1 per cent of the water movement (or turgor) in Nitella cells. The dead cellulose walls display a small electroosmotic water flow at very high current densities (under 20 volts applied potential).