bluuebunny/crossref_metadata_2025_split huggingface dataset:
SULFHYDRYL AND DISULFIDE GROUPS OF PROTEINS
Authors: Mirsky A. E. , Anson M. L. 
Published: May 2004

1. In native egg albumin no SH groups are detectable, whereas in completely coagulated albumin as many groups are detectable as are found in the hydrolyzed protein. In egg albumin partially coagulated by heat the soluble fraction contains no detectable groups, and the insoluble fraction contains the number found after hydrolysis.
2. In the reversal of denaturation of serum albumin, when insoluble protein regains its solubility, S-S groups which have been detectable in the denatured protein, disappear.
3. When egg albumin coagulates at an air-water interface, all the SH groups in the molecule become detectable.
4. In egg albumin coagulated by irradiation with ultraviolet light, the same number of SH groups are detectable as in albumin coagulated by a typical denaturing agent.
5. When serum albumin is denatured by urea, there is no evidence that S-S groups appear before the protein loses its solubility.
6. Protein denaturation is a definite chemical reaction: different quantitative methods agree in estimates of the extent of denaturation, and the same changes are observed in the protein when it is denatured by different agents. A protein molecule is either native or denatured. The denaturation of some proteins can be reversed.
THRESHOLD INTENSITY OF ILLUMINATION AND FLICKER FREQUENCY FOR THE EYE OF THE SUN-FISH
Authors: Wolf Ernst , Zerrahn-Wolf Gertrud 
Published: May 2004

The sun-fish Lepomis responds to a moving system of stripes by a motion of its body. By changing the velocity of motion of the stripe system different flicker frequencies can be produced and thus the relation of flicker frequency to critical intensity of illumination can be studied. Threshold illumination varies with flicker frequency in such a way that with increasing flicker frequency the intensity of illumination must be increased to produce a threshold response in the fish.
The curve of critical illumination as a function of frequency is made up of two distinct parts. For an intensity range below 0.04 millilambert and flicker frequencies below 10 per second, the rods are in function. For higher intensities and flicker frequencies above 10, the cones come into play. The maximum frequency of flicker which can be perceived by the fish's eye is slightly above 50 per second.
The flicker curve for the eye of Lepomis can easily be compared with that for the human eye. The extent of the curve for the fish is greater at low illuminations, the fish being capable of distinguishing flicker at illuminations lower than can the human eye. The transition of rod vision to cone vision occurs for the fish and for the human eye at the same intensity and flicker frequency. The maximum frequency of flicker which can be perceived is for both about the same.
SULFHYDRYL AND DISULFIDE GROUPS OF PROTEINS
Authors: Mirsky A. E. 
Published: May 2004

1. In the denatured proteins of skeletal muscle, the ratio of SH to S-S groups is higher than in the mixed denatured proteins of other tissues, with a single exception—the proteins of the crystalline lens.
2. The number of active SH groups in the proteins of minced muscle or in any of the protein fractions of muscle is only a fraction of the number found after the proteins have been treated with a denaturing agent.
3. The SH groups of the native proteins of muscle are activated by a rise in pH.
4. The relation between pH and number of active SH groups in the proteins of minced muscle and in the various protein fractions of muscle shows that little, if any, denatured protein is present in minced muscle.
ANOMALIES IN THE ABSORPTION SPECTRUM AND BLEACHING KINETICS OF VISUAL PURPLE
Authors: Chase Aurin M. 
Published: May 2004

Visual purple from winter frogs shows an intermediate yellow color during bleaching by light; summer extractions do not. This seasonal effect can be duplicated by variations in the hydrogen ion concentration and in the temperature of the solutions. Increasing the pH approximates the summer condition, while decreasing the pH approximates the winter condition. Temperature has no effect on the bleaching of alkaline solutions but greatly influences acid solutions. At low temperatures the bleaching of add solutions resembles the winter condition, while at higher temperatures it resembles the summer condition.
A photic decomposition product of frog retinal extractions is an acid-base indicator: it is yellow in acid and colorless in alkaline solution. Its color is not dependent upon light.
The hydrogen ion concentration of visual purple solutions does not change under illumination, nor is there a difference in the pH of summer and winter extractions. Bile salt extractions of visual purple are usually slightly acid.
The conflicting results of past workers regarding the appearance of "visual yellow" may be due to seasonal variation with its differences in temperature, or to the presence of base in the extractions. It is also possible that vitamin A may be a factor in the seasonal variation.
The photic decomposition of visual purple in bile salts solution, extracted from summer frogs, follows the kinetics of a first order reaction. Visual purple from winter frogs does not conform to first order kinetics. Photic decomposition of alkaline, winter visual purple extractions also follows a first order equation. Acid, winter extractions appear to conform to a second order equation, but this is probably an artefact due to interference by the intermediate yellow.
ELECTRIC IMPEDANCE OF ARBACIA EGGS
Authors: Cole Kenneth S. , Cole Robert H. 
Published: May 2004

The alternating current resistance and capacity of suspensions of unfertilized and fertilized eggs of Arbacia punctulata have been measured at frequencies from 103 to 1.64 x 107 cycles per second.
The unfertilized egg has a static plasma membrane capacity of 0.73 µf./cm.2 which is practically independent of frequency. The fertilized egg has a static membrane capacity of 3.1 µf./cm.2 at low frequencies which decreases to a value of 0.55 µf./cm.2 at high frequencies. The decrease follows closely the relaxation dispersion of the dielectric constant if the dissipation of such a system is ignored.
It is considered more probable that the effect is due to a fertilization membrane of 3.1 µf./cm.2 capacity lifted 1.5 µ. from the plasma membrane, the interspace having the conductivity of sea water.
The suspensions show a frequency-dependent capacity at low frequencies which may be attributable to surface conductance.
The equivalent low frequency internal specific resistance of both the unfertilized and fertilized egg is about 186 ohm cm. or about 6 times that of sea water, while the high frequency data extrapolate to a value of about 4 times sea water.
There is evidence at the highest frequencies that the current is penetrating the nucleus and other materials in the cytoplasm. If this effect were entirely due to the nucleus it would lead to a very approximate value of 0.1 µf./cm.2 for the capacity of the nuclear membrane. The measurements do not indicate any change in this effect on fertilization.
THE STRUCTURE OF THE ULTRAVIOLET ABSORPTION SPECTRA OF CERTAIN PROTEINS AND AMINO ACIDS
Authors: Coulter Calvin B. , Stone Florence M. , Kabat Elvin A. 
Published: May 2004

1. The absorption spectra of a number of proteins in the region 2500 to 3000 A. have been found to comprise from six to nine narrow bands. In consequence of variation in the relative intensity of these bands from protein to protein, the absorption curve has a characteristic configuration for each protein.
2. These bands correspond closely in position with the narrow bands which appear in the absorption spectra of tryptophan, tyrosin, and phenylalanine. Tryptophan and tyrosin each present three bands, phenylalanine shows nine.
3. The bands in the proteins are accordingly attributed to these amino acids. In the proteins the bands are displaced from the positions which they occupy in the uncombined amino acids, in most instances, by 10 to 35 A. toward longer wavelengths.
4. The absorption spectrum of Pneumococcus Type I antibody resembles that of normal pseudoglobulin but shows characteristic differences.
THE BACTERICIDAL EFFECT OF ULTRAVIOLET RADIATION ON ESCHERICHIA COLI IN LIQUID SUSPENSIONS
Authors: Hollaender Alexander , Claus Walter D. 
Published: May 2004

1. The irradiation of bacteria in liquid suspension has been made possible through: (a) the use of a specially balanced physiological salt solution which is practically non-absorbing for the wave lengths used, and which is of such composition that subsequent dilution of the bacterial suspension gives the proper number of organisms; (b) special design of the exposure cell and a very thorough method of stirring which subjects each organism equally to the radiation; (c) practically complete absorption of the incident radiation, through the use of very dense suspensions, thus eliminating the necessity for a separate determination of the absorption coefficients of the bacteria for the wave lengths used.
2. The method also provides a means for determining the effects of sub-lethal doses.
3. A formula is given for calculating from observed survival ratios the energy required to inactivate bacteria with ultraviolet radiation. The formula corrects for the protective action of non-viable organisms.
4. Data are given for the inactivation of 15 hour and 240 hour cultures of E. coli, washed and unwashed) and for 6–7 hour cultures, unwashed. These data are compared with those of other investigators.
5. A possible explanation for the differences in energy required to inactivate old, young, and standard cultures of bacteria is suggested.
6. The possible mechanism of the action of ultraviolet radiation on microorganisms is discussed.
PIGMENTS OF THE RETINA
Authors: Wald George 
Published: May 2004

1. The interrelations of visual purple, retinene, and vitamin A in the bull frog retina are analyzed in simple experiments, the results of which are presented in a series of automatically recorded spectra.
2. Observations are reported upon the distributions, properties, and concentrations of xanthophyll, vitamin A, and flavine in the pigmented tissues of the eye.
ON THE INDIVIDUAL CHARACTERISTICS OF ANIMAL AMYLASES IN RELATION TO ENZYME SOURCE
Authors: Thompson William R. , Friedman Irving 
Published: May 2004

Enzymes from various animal sources responsible for amylolytic activity as measured by a precise viscosimetric method have been investigated with regard to individual characteristics in relation to enzyme source. The principal criteria have been the course of spontaneous inactivation of preparations from different sources alone and in mixtures, and comparison of variations of relative activity with change in pH.
It is strongly indicated that the observed amylolytic activity of hog pancreatin, and that of the serum of a depancreatized dog are attributable to single chemical individuals, while that of human saliva is caused principally if not entirely by a single individual, which appears to be subject to reversible dissociation.
These three individuals are clearly distinguishable from each other.
The amylolytic activity of dog pancreatic extract is due to the same individual found in the serum of a depancreatized dog, while that of human pancreatic extract and of human serum are due to the same chemical individual found in human saliva. Thus it may be said of the amylases studied, that specificity depended upon species source rather than organ source.
Evidence of similar variations in activity with change in pH and equal sensitivity to ultraviolet light furnish strong indication that hog and human amylases have a common amylolytic radical.
ADAPTATION OF CUTANEOUS TACTILE RECEPTORS
Authors: Hoagland Hudson 
Published: May 2004

1. Both solutions of Ringer plus fifteen times the normal K content, and solutions of Ringer plus fifteen times the normal Ca content markedly hasten the adaptation of single freely branching axon endings in frog's skin to repetitive air puff stimuli.
2. The K effect is produced more rapidly than is that of Ca. The K effect is reversible by washing with Ringer's solution, while the Ca effect is not. The Ca inhibition can, however, be reversed and recovery effected by washing with K rich solutions.
3. Evidence is discussed which indicates that Ca probably plays no rôle in normal adaptation, and the experiments are interpreted as substantiating the hypothesis of adaptation due to K.
CHANGES OF APPARENT IONIC MOBILITIES IN PROTOPLASM
Authors: Osterhout W. J. V. 
Published: May 2004

In normal cells of Valonia the order of the apparent mobilities of the ions in the non-aqueous protoplasmic surface is K &gt; Cl &gt; Na. After treatment with 0.01 M guaiacol (which does not injure the cell) the order becomes Na &gt; Cl &gt; K.
As it does not seem probable that such a reversal could occur with simple ions we may assume provisionally that in the protoplasmic surface we have to do with charged complexes of the type (KXI)+, (KXII)+, where XI and XII are elements or radicals, or with chemical compounds formed in the protoplasm.
When 0.01 M guaiacol is added to sea water or to 0.6 M NaCl (both at pH 6.4, where the concentration of the guaiacol ion is negligible) the P.D. of the cell changes (after a short latent period) from about 10 mv. negative to about 28 mv. positive and then slowly returns approximately to its original value (Fig. 1, p. 14). This appears to depend chiefly on changes in the apparent mobilities of organic ions in the protoplasm.
The protoplasmic surface is capable of so much change that it does not seem probable that it is a monomolecular layer. It does not behave like a collodion nor a protein film since the apparent mobility of Na+ can increase while that of K+ is decreasing under the influence of guaiacol.
THE COLOR VISION OF DICHROMATS
Authors: Hecht Selig , Shlaer Simon 
Published: May 2004

1. Protanopes and deuteranopes show one maximum of wavelength discrimination which occurs near their neutral point in the region of 500 mµ (blue-green for color-normal). The value of the just discriminable wavelength interval Δλ is about 1 mµ at this point and is much like the normal. To either side of this, Δλ rises. It increases rapidly on the short-wave side, and slowly on the long-wave side, rising to about 50 mµ at the two ends of the spectrum.
2. The brightness distribution in the spectrum for dichromats falls only partly outside the range established for color-normals. The protanope curve is narrower than normal, and its maximum lies nearly 15 mµ to the left of it. The deuteranope curves are about the same width as the normal, and their maxima lie slightly but definitely to the right of it. The main difference between protanope and deuteranope spectrum sensitivity lies on the red side of brightness curves, where the deuteranope is strikingly higher. This difference furnishes the only reliable diagnostic sign which may be applied to an individual dichromat for separating the two types.
3. The average position for the neutral point of twenty-one protanopes is 496.5 mµ; of twenty-five deuteranopes 504.3 mµ. The range of variation in the position of neutral point is twice as great for the deuteranope as for the protanope.
4. Dichromatic gauging of the spectrum cannot yield unique mixture values for any wavelength because of the large stretches of poor wavelength discrimination. Data have therefore been secured which locate the spectral ranges that can match specific mixtures of two primaries when brightness differences are eliminated. The form of the data is much the same for a protanope and for a deuteranope; the only difference is in the relative brightness of the primaries.
5. Previously accepted anomalies in the spectral matching of dichromats which have led to the rejection of the third law of color mixture for them, have been eliminated. They are shown to have been due to the non-uniqueness of color matches and the usually disparate brightnesses of the primaries. Color mixture matches for dichromats are valid at all brightnesses.
THE COLOR VISION OF DICHROMATS
Authors: Hecht Selig , Shlaer Simon 
Published: May 2004

1. Wavelength discrimination for the colorblind is entirely determined by saturation differences in the spectrum. From the neutral point to the short-wave end, his spectrum may be completely matched by 440 mµ plus white; to the long-wave end by 650 plus white. The proportion of color to white, hence the relative saturation, changes rapidly in the region of small Δλ at the center, and slowly in regions of large Δλ at the ends.
2. The data of spectrum gauging with two primaries (color mixture) by the dichromat are shown to contain the saturation distribution in the spectrum for the dichromat. This is because each mixture of primaries may be considered as composed of a mixture which matches white and of an excess of one primary. The data when so computed yield saturation distributions almost identical with those found by direct measurement, and show that on each side of the neutral point the basis of color mixture for the colorblind lies in saturation and not in hue differences.
3. To judge by these measurements, the spectrum for the protanope and deuteranope is composed of only two hues, themselves probably of low saturation, situated one at each end. Toward the center these hues decrease still more in saturation until they completely disappear in the white of the neutral point.
TEMPERATURE AND CRITICAL ILLUMINATION FOR REACTION TO FLICKERING LIGHT
Authors: Crozier W. J. , Wolf Ernst , Zerrahn-Wolf Gertrud 
Published: May 2004

The curve connecting mean critical illumination (Im) and flicker frequency (F) for response of the sunfish Lepomis (Enneacanthus gloriosus) to flicker is systematically displaced toward lower intensities by raising the temperature. The rod and cone portions of the curve are affected in a similar way, so that (until maximum F is approached) the shift is a nearly constant fraction of Im for a given change of temperature. These relationships are precisely similar to those found in the larvae of the dragonfly Anax. The modifications of the variability functions are also completely analogous. The effects found are consistent with the view that response to flicker is basically a matter of discrimination between effect of flashes of light and their after effects,—a form of intensity discrimination. They are not consistent with the stationary state formulation of the shape of the flicker curve.
An examination of the relationships between the cone portion and the rod portion of the curves for the sunfish suggests a basis for their separation, and provides an explanation for certain "anomalous" features of human flicker curves. It is pointed out how tests of this matter will be made.
THE POTENTIAL AND RESPIRATION OF FROG SKIN
Authors: Ponder Eric , Macleod John 
Published: May 2004

Measurements of the O2 consumption and of the potential of frog skin, made under comparable conditions, show that the homologous carbamates (ethyl, propyl, butyl, and amyl) reduce both the O2 consumption and the potential, but not in a similar manner. In this respect, the effect of the carbamates is like the effect of reduction in O2 tension. The simple lysins (saponin and the bile salts), on the other hand, abolish the potential without reducing the O2 consumption at all.
Irrespective of whether one considers the concentration of carbamate in the entire system or the amount of carbamate adsorbed by the frog skin, Traube's rule relating the effect of a carbamate to its position in the homologous series does not seem to apply.
THE COAGULATION OF MYOSIN IN MUSCLE
Authors: Mirsky A. E. 
Published: May 2004

1. Muscle can be prepared in the form of a dry powder in which myosin exists in a state similar to that in intact muscle. As in intact muscle, myosin in powdered muscle is soluble and can be caused to rapidly coagulate.
2. Restoring to powdered muscle the quantity of water previously removed causes coagulation of myosin. The rate of coagulation is considerably slower at 0° than at 20°.
3. Adding the powder to a large volume of dilute salt solution also results in coagulation.
4. The water soluble constituents of muscle can be removed from the powder without thereby causing coagulation. Coagulation occurs in water extracted muscle when it is suspended in a dilute salt solution.
5. Coagulation of myosin in muscle resembles the coagulation of myosin caused by dehydration.
6. Myosin coagulates readily only when it is imbedded in the structure of muscle. The significance for coagulation of the arrangement of myosin particles in muscle has been indicated.
A PHASE RULE STUDY OF THE PROTEINS OF THE BLOOD SERUM: A COMPARISON OF THE PROTEINS OF HUMAN, RAT, AND HORSE SERUM
Authors: Jameson Eloise , Roberts Dorothy Brown 
Published: May 2004

There are four different kinds of protein in blood serum as shown by the solubility curves.
They must be either single proteins, several continuous series of compounds, or solid solutions.
The solid protein phases are hydrated.
There are definite sex and species differences.
THE EFFECT OF HYDROGEN ION CONCENTRATION UPON THE INDUCTION OF POLARITY IN FUCUS EGGS
Authors: Whitaker D. M. 
Published: May 2004

1. The eggs of Fucus furcatus develop perfectly in sea water acidified to pH 6.0. They are retarded at pH 5.5. At pH 5.0 they do not develop, nor do they cytolize.
2. In normal sea water in the dark at 15°C., eggs develop rhizoids on the sides in the resultant direction of a mass of neighboring eggs. The polarity and the whole developmental pattern of the embryo is thereby induced. This inductive effect does not operate, however, unless the directing mass is an appreciable aggregation of cells (10 or more), or unless there are numerous other eggs in the dish. A group of five eggs alone in a dish do not carry out mutual inductions. Two eggs alone in a dish do not develop rhizoids toward each other.
3. When the sea water is acidified to pH 6.0 all sizes of aggregations carry out mutual inductions. Two eggs alone in a dish now develop rhizoids on the sides toward each other, provided they are not more than about 4 egg diameters apart.
4. Increased hydrogen ion concentration thus augments or intensifies the mutual inductive effect.
5. This may explain why only larger masses of eggs show inductions in normal sea water, since presumably the larger masses considerably increase the hydrogen ion concentration locally.
6. The nature of the inductive action is discussed.
7. In acidified sea water at pH 6.0, compared with normal sea water at pH 7.8–8.0, the rhizoids originate and extend with a strongly increased downward component. The substrate then forces further extension or growth of the rhizoid to be in the plane of the substrate.