bluuebunny/crossref_metadata_2025_split huggingface dataset:
ELECTRIC IMPEDANCE OF THE SQUID GIANT AXON DURING ACTIVITY
Authors: Cole Kenneth S. , Curtis Howard J. 
Published: May 2004

Alternating current impedance measurements have been made over a wide frequency range on the giant axon from the stellar nerve of the squid, Loligo pealii, during the passage of a nerve impulse. The transverse impedance was measured between narrow electrodes on either side of the axon with a Wheatstone bridge having an amplifier and cathode ray oscillograph for detector. When the bridge was balanced, the resting axon gave a narrow line on the oscillograph screen as a sweep circuit moved the spot across. As an impulse passed between impedance electrodes after the axon had been stimulated at one end, the oscillograph line first broadened into a band, indicating a bridge unbalance, and then narrowed down to balance during recovery. From measurements made during the passage of the impulse and appropriate analysis, it was found that the membrane phase angle was unchanged, the membrane capacity decreased about 2 per cent, while the membrane conductance fell from a resting value of 1000 ohm cm.2 to an average of 25 ohm cm.2
The onset of the resistance change occurs somewhat after the start of the monophasic action potential, but coincides quite closely with the point of inflection on the rising phase, where the membrane current reverses in direction, corresponding to a decrease in the membrane electromotive force. This E.M.F. and the conductance are closely associated properties of the membrane, and their sudden changes constitute, or are due to, the activity which is responsible for the all-or-none law and the initiation and propagation of the nerve impulse. These results correspond to those previously found for Nitella and lead us to expect similar phenomena in other nerve fibers.
INTRACELLULAR PHAGE PRECURSOR
Authors: Krueger A. P. , Scribner E. J. 
Published: May 2004

1. Staphylococci activated by rapid growth in the presence of excess O2 and subsequently brought to a resting state by storage in Locke's solution at 5°C. produce a significant rise in [phage] when added to phage-containing solutions.
2. For satisfactory activation the staphylococci require a period of active growth in the presence of oxygen. Activation proceeds best on the acid side of neutrality although variation in pH from 5 to 9 has relatively little effect. Activated cells retain their phage-augmenting property for from 4 to 24 hours, and this property may be destroyed by heating the cells at temperatures which do not kill them. The critical thermal increment for heat inactivation is 90,000 suggesting that the reaction involves protein denaturation.
3. The reaction between activated cells and phage has the following characteristics:
A. It is complete in 1 to 2 minutes after mixing the reactants.
B. The increase in phage does not depend upon bacterial growth nor does it involve any untoward effect on the titration system.
C. Serum prepared by injecting rabbits with normal live staphylococci or with activated staphylococci when mixed with activated cells before the addition of phage will prevent the customary increase in [phage].
4. The phage-producing reaction which follows the addition of activated cells to phage can be interpreted in terms of the precursor theory. It is likely that the precursor either is a protein or contains a protein as an essential component.
5. There is no way of deciding at present whether the reaction between phage and precursor represents the hydrolytic cleavage of a protein or whether it is the final step in a synthesis catalyzed by phage.
THE FLICKER RESPONSE CONTOUR FOR THE FROG
Authors: Crozier W. J. , Wolf Ernst 
Published: May 2004

The flicker response contour for the frog Rana pipiens exhibits the duplex character typical for most vertebrates. By comparison (under the same conditions of temperature, 21.5°, and light-time fraction, = 0.5), the low intensity section of the F - log I curve is the smallest thus far found.
The cone portion of the curve is satisfactorily described by a probability integral. The rod part represents the addition of a small group of sensory effects upon the lower end of the cone curve, from which it can be analytically separated.
The relation between the two groups of sensory effects permits certain tests of the rule according to which (in homogeneous data) Im and σ1I1 are in direct proportion.
PHYSICOCHEMICAL PROPERTIES OF THE PROTEOLYTIC ENZYME FROM THE LATEX OF THE MILKWEED, ASCLEPIAS SPECIOSA TORR. SOME COMPARISONS WITH OTHER PROTEASES
Authors: Winnick Theodore , Davis Alva R. , Greenberg David M. 
Published: May 2004

1. The rates of heat inactivation of papain, bromelin, and asclepain were determined at several different temperatures. Papain was by far the most resistant to heat.
2. The destruction of papain at 75–83° and bromelin at 55–70° followed the course of a first order reaction, except that for longer times of heating, bromelin (at 60–70°) was inactivated more rapidly than the first order equation required.
3. The rate of inactivation of asclepain at 55–70° followed the second order equation.
4. The critical thermal increments of inactivation of papain and bromelin, calculated with the van't Hoff-Arrhenius equation, were of the same high order that has been found for protein denaturation. The increment for asclepain was somewhat lower.
STABILIZATION OF SPIDER CRAB NERVE MEMBRANES BY ALKALINE EARTHS, AS MANIFESTED IN RESTING POTENTIAL MEASUREMENTS
Authors: Guttman Rita 
Published: May 2004

1. The alkaline earths, Ba, Sr, Ca, and Mg, in isotonic solutions of their chlorides, have, in general, no effect upon the resting potential of non-medullated spider crab nerve.
2. Ba, Sr, and Ca can, however, prevent the depressing action of K upon the resting potential. The order of effectiveness of these ions in this regard is the following: Ba &gt; Sr &gt; Ca.
3. Ba, Sr, Ca, and Mg oppose the depressing action of veratrine sulfate upon the resting potential. The order of effectiveness is Ba &gt; Sr &gt; Ca &gt; Mg. The relation between drop in potential caused by veratrine sulfate and the logarithm of the veratrine sulfate concentration is a linear one.
4. The action of various other organic ions and molecules which depress the resting potential: saponin, amyl urethane, chloral hydrate, and Na salicylate is neutralized by Ba.
5. Hypertonic sea water solutions do not affect the resting potential. Also, preliminary experiments indicate that the nerves do not shrink in hypertonic solutions although they swell in hypotonic sea water.
6. The alkaline earths depress excitability reversibly. The various organic agents which depress the resting potential also depress excitability, in most cases, reversibly, but the concentrations necessary to depress excitability are much smaller than those necessary to depress the resting potential.
7. The relation of these findings to theories put forward as possible explanations of resting potential phenomena is considered.
THE RÔLE OF ORGANIC SUBSTRATES IN PHOTOSYNTHESIS OF PURPLE BACTERIA
Authors: Foster Jackson W. 
Published: May 2004

A representative of the photosynthetic non-sulfur purple bacteria (Athiorhodaceae) capable of using simple alcohols has been isolated in pure culture.
By means of quantitative analysis of cultures at different stages of development it has been shown that this organism converts isopropanol quantitatively into acetone, simultaneously reducing CO2 in the light. The data can be represented by the equation
2 CH3CHOHCH3 + CO2 → 2 CH3COCH3 + (CH2O) + H2O.
Manometric experiments with suspensions of resting cells have fully corroborated the results obtained with growing cultures.
The experiments have conclusively proved that an organic substrate may fulfill exclusively the function of hydrogen donor for the photochemical CO2-reduction in purple bacteria photosynthesis.
THE ELECTRICAL CAPACITY OF VALONIA
Authors: Blinks L. R. , Skow R. K. 
Published: May 2004

Impaled cells of Valonia were balanced in a Wheatstone bridge against a simple series-parallel circuit of two resistances and a capacity, the transient charge and discharge curves at make and break of direct current being recorded with a string galvanometer. With the resistances properly balanced, a series of characteristic deflections resulted when the balancing capacity was varied. With many cells, no complete capacity balance was ever attained over the entire transient time course; but instead either a monophasic or diphasic residual deflection always remained. This behavior is comparable to that of a polarizing electrode in D.C., although not so clearly marked; and it is concluded that Valonia usually has an appreciable polarization component, probably in parallel with a static capacity.
However, some cells can be balanced almost completely against a mica condenser of proper value, which indicates that they display a nearly pure static capacity under some conditions. This static state could be produced experimentally by exposure to weak acids (acetic, carbonic, etc.) and by metabolic agents probably inducing internal acidity (low oxygen tension, long exposure to cold, narcotics, etc.). Conversely, penetrating weak bases, such as ammonia, abolished the static capacity, or even any regular polarization. Light acts something like ammonia, after an initial "acid gush" anomaly. Most of these agents likewise affect the P.D. and its response to external ionic alterations, and it seems likely that the change in capacity type reflects altered ionic permeabilities and relative mobilities.
ON THE RELATION BETWEEN GROWTH AND RESPIRATION IN THE AVENA COLEOPTILE
Authors: Commoner Barry , Thimann Kenneth V. 
Published: May 2004

1. The growth of Avena coleoptile sections in sucrose and auxin solutions is inhibited by various substances which are known to act as dehydrogenase inhibitors.
2. Iodoacetate, which is particularly active in this connection, inhibits all growth at a concentration of 5 x 10–5 M, but produces only a slight inhibition of oxygen uptake.
3. The growth inhibition by iodoacetate is completely removed by malate and fumarate, and to a lesser extent by succinate and pyruvate.
4. These acids themselves increase the effect of auxin on growth and also increase the respiration of the coleoptile sections, but only if auxin is present.
5. When sections have been soaked in malate or fumarate, the addition of auxin considerably increases the total respiration. Further, the concentration range over which this increase takes place parallels that active in promoting growth.
6. The four-carbon acids provide a respiratory system which is part of the chain of growth processes, and which is in some way catalyzed by auxin. It represents a small but variable fraction of the total respiration.
THEORY AND MEASUREMENT OF VISUAL MECHANISMS
Authors: Crozier W. J. , Wolf Ernst 
Published: May 2004

The relation between flash duration and mean critical intensity (white light) for threshold recognition of visual flicker, as a function of flash frequency, was investigated by means of measurements at five values of the light-time fraction: 0.10, 0.25, 0.50, 0.75, 0.90, with flash frequencies of the interrupted beam ranging from 2 to 60 per second. A square area, 6.1 x 6.1°, centrally fixated) was viewed monocularly; the discriminometer used provides automatically an artificial pupil 1.8 mm. in diameter. Except for the slight day-to-day fluctuation in the magnitudes of the parameters, the data for the observer used are shown to form an essentially homogeneous group.
As for other animals tested, the F - log Im curve is enlarged and moved toward lower flash intensities as the light-time fraction is decreased. The high intensity segments of the duplex curves are fitted by normal probability integrals for which F max. and the abscissa of inflection are rectilinear functions of tL(tL + tD), with opposite slopes. The third parameter, (σ'log I, is invariant.
The low intensity segments are composites, their shapes determined by the summation of the lower part of the high intensity curve with an overlapping low intensity population of effects. Both the rising and the declining branches of this latter assemblage suffer competitive partial suppression by the effects in the high intensity population. The detailed analysis shows that these results are consistent with the theory of the central, rather than peripheral, location of the dynamically recognizable elements in the determination of flicker.
STUDIES IN THE PHYSIOLOGY OF FUSARIA. THE RESPIRATORY AND FERMENTATIVE MECHANISMS
Authors: Gould Bernard S. , Tytell Alfred A. 
Published: May 2004

1.Fusarium tricothecoides was selected for a study of the respiratory and fermentative activities of Fusaria. "Resting cell" suspensions were investigated by the Barcroft manometric technique.
2. The results of the investigation indicate clearly that the mechanism of endogenous metabolism (respiration) is distinct from the exogenous mechanism (fermentation). Anaerobically no significant CO2 production is apparent without added substrate. In the presence of glucose the anaerobic CO2 evolution is practically equal to the added CO2 evolved aerobically in the presence of added glucose.
Low concentrations of iodoacetate or fluoride selectively poison the exogenous mechanism but do not affect the endogenous mechanism.
Alcohol is not produced in the course of endogenous metabolism, but is produced in the presence of added glucose.
3. A study of the metabolism of the organism throughout its entire growth phase from 1 to 7 days has been made.
4. The ability of suspensions of Fusarium sp. H., obtained by growth on a variety of common substrates, to attack a large number of carbon sources with the production of exogenous CO2 was determined. It is found that organisms grown on glucose will attack only glucose, mannose, and fructose, but none of the common intermediary metabolites except pyruvic acid. Organisms grown on galactose attack galactose, as well as the other hexoses, indicating an adaptive mechanism.
5. An identical mechanism for the dissimilation of glucose, mannose, and galactose is indicated since no additive effects with these substrates were observed. Growths on non-hexose carbon sources attack glucose slightly under the experimental conditions with the evolution of CO2, but do not attack any other substrate. This would indicate a residual glucose-dissimilating mechanism in all growths investigated.
6. Striking similarities between the general metabolism of resting suspensions of Fusarium sp. H. and resting suspensions of yeast cells are apparent.
ANAEROBIC GLYCOGENOLYSIS IN THE MUSCLES OF RANA PIPIENS LIVING AT LOW TEMPERATURES
Authors: Barger A. N. , Johnson R. E. 
Published: May 2004

1. A considerable proportion of R. pipiens caught in the spring and stored without food for several weeks at about 4°C. had gastrocnemii that did not break down glycogen when they contracted anaerobically to complete exhaustion. A smaller number of the same muscles did not produce lactate.
2. There was no evident relation between failure to break down glycogen and the glycogen content of such muscles, some of which had more than 500 mg. of glycogen per 100 gm. of tissue.
3. The hypothesis of Meyerhof and his followers that aerobic contraction of frog muscles may at times take place with sources of energy other than carbohydrate is therefore extended to include anaerobic contraction.
THE EFFECT OF SONIC VIBRATIONS ON PHAGE, PHAGE PRECURSOR, AND THE BACTERIAL SUBSTRATE
Authors: Krueger A. P. , Brown B. B. , Scribner E. J. 
Published: May 2004

1. A nickel tube magneto-striction oscillator of 320 watts output producing sonic vibrations of 9,300 cycles per second frequency is described. Certain structural innovations contribute to operating efficiency and permit more convenient exposure of test materials than in earlier types.
2. The rate of phage inactivation by sonic waves proceeds logarithmically with time and serves as a satisfactory measure of energy output during operation of the generator. The curve for phage inactivation taking place in the presence of homologous staphylococci follows that for phage alone but soon reaches a plateau after which no further loss of activity is noted. In general higher concentrations of bacteria more effectively inhibit phage destruction than do lower concentrations.
3. Cells that have attained a resting state after a preliminary phase of rapid growth normally have the capacity of inducing a very rapid and marked increase in [phage] when added to phage. This effect has been attributed to the presence of intracellular phage precursor. The store of phage precursor in activated cells is destroyed by sonic waves in about 30 minutes. The number of cells (plate count) shows no reduction until after the precursor is entirely inactivated.
4. Attempts to extract phage precursor from activated staphylococci by exposing the cells to sonic vibrations were unsuccessful.
X-RAY AND CRYSTALLOGRAPHIC STUDIES OF PLANT VIRUS PREPARATIONS. III
Authors: Bernal J. D. , Fankuchen I. 
Published: May 2004

These papers give an account of an optical and x-ray examination of preparations of plant virus substances isolated by Bawden and Pirie, in particular of those of tobacco mosaic disease. They open with a historical survey of the work, indicating the order in which new phenomena were discovered. The subsequent treatment is divided into three parts:
I. Introduction and preparation of specimens.
II. Modes of aggregation of virus particles.
III. (1) The structure of the particles.
(2) Biological implications.
Part I, after an historical introduction, describes the method of preparation, from solutions of the virus, of optically oriented specimens of different concentrations. For their examination special x-ray apparatus was developed, in particular cameras working with very low angles and capable of indicating spacings up to 1000 Å.
In Part III, Section 1 deals with the x-ray evidence on the internal structure of the particles. Even in solution, they have an inner regularity like that of a crystal. Virus preparations are thus in a sense doubly crystalline. Closer analysis reveals that the x-ray patterns are not directly comparable to those of a crystal as many of the reflections do not obey Bragg's law, but can be understood on the theory of gratings of limited size. The structure seems to consist of sub-units of the dimensions of approximately 11 Å cube, fitted together in a hexagonal or pseudohexagonal lattice of dimensions—a = 87 Å, c = 68 Å. Contrary to what earlier observations seemed to indicate, the particle seems to be virtually unchanged by drying and must therefore contain little water. There are marked resemblances with the structure of both crystalline and fibrous protein, but the virus structure does not belong to any of the classes hitherto studied. There are indications that the inner structure is of a simpler character than that of the molecules of crystalline proteins.
Part III, Section 2 contains a comparative study of the optical and x-ray examinations of three strains of tobacco mosaic virus, two of cucumber disease virus, two of potato virus X, and the virus of bushy stunt disease of tomato. In the last case x-ray measurement confirmed the deduction from its cubic crystal habit that it was composed of spherical rather than long particles, and showed that these had a diameter when dry of 276 Å and were arranged in a body-centred cubic close packing. This single example is sufficient to show that the elongated particle form which gives rise to all the anomalous physical properties of the other viruses studied is of no essential biological importance. The similarity and differences observed between the physical properties of these preparations run closely parallel to their clinical and serological classification. Finally, the biological implications of these results are discussed together with possible applications of the new methods of examination to the study of colloid and biological problems.
DETERMINATION OF CERTAIN AMINO ACIDS IN CHYMOTRYPSINOGEN, AND ITS MOLECULAR WEIGHT
Authors: Brand Erwin , Kassell Beatrice 
Published: May 2004

1. A preparation of chymotrypsinogen, obtained from Dr. M. Kunitz, was analyzed for sulfur, the sulfur amino acids, tyrosine, and tryptophane.
2. The protein sulfur of chymotrypsinogen was accounted for as methionine, cysteine, and cystine.
3. A method is presented for calculating the minimum molecular weight of a protein from the distribution of the sulfur amino acids. In the case of chymotrypsinogen, the calculated minimum molecular weight was found to be the actual molecular weight.
4. The molecular weight of chymotrypsinogen is 36,700 by amino acid analysis as compared to 36,000 by osmotic pressure measurements of Kunitz and Northrop. Chymotrypsinogen contains per mol 17 atoms of sulfur, 3 residues of methionine, 4 of cysteine, 10 of half-cystine (i.e. 5 S—S linkages), 6 of tyrosine, and 10 of tryptophane.
5. The tryptophane content of chymotrypsinogen (5.51 per cent) is the highest of any protein so far on record.
6. Chymotrypsinogen contains no reactive SH groups, although it yields cysteine on hydrolysis. This may be due either to preformed but unreactive SH groups or to S—X groups. The term S—X group is used to denote the substitution of the sulfhydryl hydrogen by a constituent X; hydrolysis yields SH groups: S—X + HOH = SH + X—OH.
THE PHYSIOLOGICAL EFFECTS OF l-TYROSINE AND l-PHENYL-ALANINE ON THE RATE AND QUALITY OF PULSATION IN THE SEVENTY-TWO HOUR EXTIRPATED EMBRYONIC CHICK HEART
Authors: Miller Bernard J. , Ciacci Vincent W. 
Published: May 2004

1. 72 hour isolated chick hearts show an increase in pulsation rate when placed in M/1000, M/10,000, and M/50,000 l-tyrosine solutions. The optimal effect is seen in M/10,000 and M/50,000 l-tyrosine.
2. All hearts show disturbance of rhythm either in the form of irregular rhythm or heart block.
3. 62 hour isolated chick hearts are not susceptible to l-tyrosine while 96 hour hearts are markedly sensitive.
4. 72 hour isolated chick hearts placed in 1 part in 10,000 and 1 part in 50,000 l-epinephrine show approximately the same effects as were seen with l-tyrosine.
5. 72 hour isolated chick hearts placed in M/1000 and M/10,000 l-phenylalanine show an initial depression followed by an l-tyrosine effect.
THE FLOCCULATION MAXIMUM (pH) OF FIBRINOGEN AND SOME OTHER BLOOD-CLOTTING REAGENTS. (RELATIVE TURBIDIMETRY WITH THE EVELYN PHOTOELECTRIC COLORIMETER)
Authors: Ferguson John H. 
Published: May 2004

By means of a novel adaptation of the Evelyn photoelectric colorimeter to the measurement of relative turbidities, the question of the flocculation maximum (F.M.) in acetate buffer solutions of varying pH and salt content has been studied on (a) an exceptionally stable prothrombin-free fibrinogen and its solutions after incipient thermal denaturation and incomplete tryptic proteolysis, (b) plasma, similarly treated, (c) prothrombin, thrombin, and (brain) thromboplastin solutions.
All the fibrinogens show a remarkable uniformity of the precipitation pattern, viz. F.M. =4.7 (±0.2) pH in salt-containing buffer solutions and pH = 5.3 (±0.2) in salt-poor buffer (N/100 acetate). The latter approximates the isoelectric point (5.4) obtained by cataphoresis (14). There is no evidence that denaturation or digestion can produce any "second maximum." The data support the view that fibrin formation (under the specific influence of thrombin) is intrinsically unrelated to denaturation and digestion phenomena, although all three can proceed simultaneously in crude materials. A criticism is offered, therefore, of Wöhlisch's blood clotting theory.
Further applications of the photoelectric colorimeter to coagulation problems are suggested, including kinetic study of fibrin formation and the assay of fibrinogen, with a possible sensitivity of 7.5 mg. protein in 100 cc. solution.