bluuebunny/crossref_metadata_2025_split huggingface dataset:
CONCENTRATION AND PURIFICATION OF BACTERIOPHAGE
Authors: Northrop John H. 
Published: May 2004

1. A method for isolating a nucleoprotein from lysed staphylococci culture is described.
2. It is homogeneous in the ultracentrifuge and has a sedimentation constant of 650 x 10–13 cm. dyne–1 sec.–1, corresponding to a molecular weight of about 300,000,000.
3. The diffusion coefficient varies from about 0.001 cm.2/day in solutions containing more than 0.1 mg. protein/ml. to 0.02 in solutions containing less than 0.001 mg. protein/ml. The rate of sedimentation also decreases as the concentration decreases. It is suggested, therefore, that this protein exists in various sized molecules of from 500,000–300,000,000 molecular weight, the proportion of small molecules increasing as the concentration decreases.
4. This protein is very unstable and is denatured by acidity greater than pH 5.0, by temperature over 50°C. for 5 minutes. It is digested by chymo-trypsin but not by trypsin.
5. The loss in activity by heat, acid, and chymo-trypsin digestion is roughly proportional to the amount of denatured protein formed under these conditions.
6. The rate of diffusion of the protein is the same as that of the active agent.
7. The rate of sedimentation of the protein is the same as that of the active agent.
8. The loss in activity when susceptible living or dead bacteria are added to a solution of the protein is proportional to the loss in protein from the solution. Non-susceptible bacteria remove neither protein nor activity.
9. The relative ultraviolet light absorption, as determined directly, agrees with that calculated from Gates' inactivation experiments in the range of 2500–3000 Å. u. but is somewhat greater in the range of 2000–2500 Å. u.
10. Solubility determinations showed that most of the preparations contained at least two proteins, one being probably the denatured form of the other. Two preparations were obtained, however, which had about twice the specific activity of the earlier ones and which gave a solubility curve approximating that of a pure substance.
11. It is suggested that the formation of phage may be more simply explained by analogy with the autocatalytic formation of pepsin and trypsin than by analogy with the far more complicated system of living organisms.
AN ULTRACENTRIFUGAL ANALYSIS OF CONCENTRATED STAPHYLOCOCCUS BACTERIOPHAGE PREPARATIONS
Authors: Wyckoff Ralph W. G. 
Published: May 2004

Analytical observations have been made with the air ultracentrifuge on concentrated staphylococcus bacteriophage solutions and on these solutions inactivated by alkali, chymo-trypsin, and heat.
All active solutions contain a homogeneous heavy component that sediments with a constant of s20° = ca. 650 x 10–13 cm. sec.–1 dynes–1, has an apparent density of ca. 1.20, and a molecular weight probably not less than 200 millions. There is also present some very light ultraviolet-absorbing material which is not a carrier of bacteriophage activity. The amount of the heavy component is not strictly proportional to the bacteriophage activity so that if the activity resides in it, as appears to be the case, inactivation may occur without measurable change in molecular size and shape.
When the bacteriophage solutions are inactivated by chymo-trypsin, the heavy component is not disrupted but the sedimenting boundaries have always been fairly diffuse. As the activity gradually disappears from alkaline solutions, the heavy component is replaced by unsedimentable material. When a solution is inactivated by heating, a dilute gel is produced which sediments with an exceptionally sharp boundary in a relatively intense centrifugal field,
THE EFFECT OF AUXINS ON PROTOPLASMIC STREAMING. II
Authors: Sweeney Beatrice Marcy , Thimann Kenneth V. 
Published: May 2004

1. A further study has been made of the effect of indole-3-acetic acid (auxin) on protoplasmic streaming in the epidermal cells of the Avena coleoptile.
2. The transient nature of the effect of auxin, both in accelerating and retarding streaming, is due to the temporary exhaustion of carbohydrate from the tissues. In presence of 1 per cent fructose or some other sugars the acceleration or retardation of streaming by auxin is not transient, but is maintained for at least 2 hours.
3. The retardation of streaming brought about by concentrations of auxin above 0.5 mg. per liter is due to oxygen deficiency This has been confirmed in several ways.
4. It follows that the effect of auxin is to increase the respiration of the coleoptile tissue.
5. Younger coleoptiles, 3 cm. long, are sensitive to lower concentrations of auxin than those 5 cm. long, and more readily exhibit oxygen deficiency as a result of the action of auxin. However, after decapitation their response to auxin more closely resembles that of 5 cm. coleoptiles.
6. The retardation of streaming in such coleoptiles, resulting from oxygen deficiency, is delayed by very dilute solutions of histidine. On this basis an explanation is suggested for the results of Fitting on streaming in Vallisneria leaves.
7. The mean rate of streaming in control untreated coleoptiles in pure water varies with the time of year, but not with the time of day.
8. The results support the view that auxin accelerates an oxygen-consuming process which controls the rate of protoplasmic streaming, and that the latter controls growth. The substrate for this process is probably sugar.
9. It is suggested that auxin also accelerates another oxygen-consuming process, which may withdraw oxygen from the process which controls streaming rate and hence cause retardation of the latter.
TRANSFORMATION OF SWINE PEPSINOGEN INTO SWINE PEPSIN BY CHICKEN PEPSIN
Authors: Herriott Roger M. , Bartz Quentin R. , Northrop John H. 
Published: May 2004

Activation of swine pepsinogen with chicken pepsin results in the formation of swine pepsin.
Activation of chicken pepsinogen with swine pepsin results in the formation of chicken pepsin.
The structure responsible for the species specificity of the enzyme is therefore present in the inactive precursor.
ELECTRIC IMPEDANCE OF SINGLE MARINE EGGS
Authors: Cole Kenneth S. , Curtis Howard J. 
Published: May 2004

Alternating current impedance measurements have been made on several single marine eggs over the frequency range from 1 to 2500 kilocycles per second. The eggs were placed in the center of a short capillary made by heating the end of a 2 mm. thin walled glass tube until it nearly closed, and electrodes were placed in the sea water on each side of the egg.
When it is assumed that the membrane conductance is negligible, the membrane capacity and internal resistances of unfertilized and fertilized Arbacia eggs agree with the values obtained from suspensions. Preliminary data on centrifugally separated half Arbacia eggs, and whole Cumingia and Chaetopterus eggs are given.
FORMATION OF TRYPSIN FROM TRYPSINOGEN BY AN ENZYME PRODUCED BY A MOLD OF THE GENUS PENICILLIUM
Authors: Kunitz M. 
Published: May 2004

1. A powerful kinase which changes trypsinogen to trypsin was found to be present in the synthetic liquid culture medium of a mold of the genus Penicillium.
2. The concentration of kinase in the medium is increased gradually during the growth of the mold organism and continues to increase for some time even after the mold has ceased growing.
3. Mold kinase transforms trypsinogen to trypsin only in an acid medium. It differs thus from enterokinase and trypsin which activate trypsinogen best in a slightly alkaline medium.
4. The action of the mold kinase in the process of transformation of trypsinogen is that of a typical enzyme. The process follows the course of a catalytic unimolecular reaction, the rate of formation of a definite amount of trypsin being proportional to the concentration of kinase added. The ultimate amount of trypsin formed, however, is independent of the concentration of kinase used.
5. The formation of trypsin from trypsinogen by mold kinase is not accompanied by any measurable loss of protein.
6. The temperature coefficient of formation of trypsin from trypsinogen by mold kinase varies from Q5–15 = 1.70 to Q25–30 = 1.25 with a corresponding variation in the value of µ from 8100 to 4250.
7. Trypsin formed from trypsinogen by means of mold kinase is identical in crystalline form with the crystalline trypsin obtained by spontaneous autocatalytic activation of trypsinogen at pH 8.0. The two products have within the experimental error the same solubility and specific activity. A solution saturated with the crystals of either one of the trypsin preparations does not show any increase in protein concentration or activity when crystals of the other trypsin preparation are added.
8. The Penicillium mold kinase has a slight activating effect on chymo-trypsinogen the rate being only 1–2 per cent of that of trypsinogen. The activation, as in the case of trypsinogen, takes place only in an acid medium.
9. Mold kinase is rapidly destroyed when brought to pH 6.5 or higher, and also when heated to 70°C. In the temperature range of 50–60°C. the inactivation of kinase follows a unimolecular course with a temperature coefficient of Q10 = 12.1 and µ = 53,500. The molecular weight of mold kinase, as determined by diffusion, is 40,000.
BRIGHTNESS DISCRIMINATION AS A FUNCTION OF THE DURATION OF THE INCREMENT IN INTENSITY
Authors: Graham C. H. , Kemp E. H. 
Published: May 2004

1. This investigation has been concerned with an analysis of brightness discrimination as it is influenced by the duration of ΔI. The durations used extend from 0.002 second to 0.5 second.
2. ΔI/I values at constant intensity are highest for the shortest duration and decrease with an increase in duration up to the limits of a critical exposure time. At durations longer than the critical duration the ratio ΔI/I remains constant.
3. The Bunsen-Roscoe law holds for the photolysis due to ΔI. This is shown by the fact that, within the limits of a critical duration, the product of ΔI and exposure time is constant for any value of prevailing intensity, I.
4. At durations greater than the critical duration the Bunsen-Roscoe law is superseded by the relation ΔI = Constant. This change of relation is considered in the light of Hartline's discussion (1934).
5. The critical duration is a function of intensity. As intensity increases the critical duration decreases.
6. Hecht's theory (1935) accounts for the data of this experiment if it be assumed that brightness discrimination is determined by a constant amount of photolysis.
CHANGES OF APPARENT IONIC MOBILITIES IN PROTOPLASM
Authors: Osterhout W. J. V. 
Published: May 2004

Lowering the pH of sea water from 8.2 to 6.4 lowers the positive P.D. of Halicystis reversibly (this does not happen with Valonia).
Exposure to sea water at pH 6.4 does not affect the apparent mobility of Na+ or of K+ (this agrees with Valonia).
Guaiacol makes the P.D. of Halicystis less positive (in Valonia it has the opposite effect).
Exposure to guaiacol does not reverse the effect of KCl in Halicystis which in this respect differs from Valonia.
The P.D. can be changed from 66 mv. positive to 23 mv. negative by the combined action of KCl and guaiacol.
Exposure to guaiacol affects Halicystis and Valonia similarly in respect to their behavior with dilute sea water. Normally the dilute sea water makes the P.D. more negative but after sufficient exposure to guaiacol dilute sea water either produces no change in P.D. or makes it more positive. In the latter case we may assume that the apparent mobility of Na+ has become greater than that of Cl- as the result of the action of guaiacol. (Normally the apparent mobility of Cl- is greater than that of Na+.)
In Halicystis, as in Valonia and in Nitella, an organic substance can greatly change the apparent mobilities of certain inorganic ions (K+ or Na+).
FACTORS LIMITING BACTERIAL GROWTH
Authors: Hershey A. D. , Bronfenbrenner J. 
Published: May 2004

1. Measurements of the rate of oxygen uptake per cell in transplants of Bacterium coli from cultures of this organism in different phases of growth have given results in essential agreement with the observations of others.
2. Correlations of viable count, centrifugable nitrogen, and turbidity, with oxygen consumption, indicate that the increased metabolism during the early portion of the growth period is quantitatively referable to increased average size of cells.
3. Indirect evidence has suggested that the initial rate of growth of transplants is not related to the phase of growth of the parent culture.
ELECTROKINETIC PHENOMENA
Authors: Abramson Harold A. , Moyer Laurence S. 
Published: May 2004

1. Although the isoelectric points of dissolved cystine, tyrosine, and aspartic acid molecules lie at widely differing pH values, the isoelectric points of the surfaces of these substances in the crystalline state are all near pH 2.3. This was found to be true in solutions of hydrochloric acid and in acetate buffers of approximately constant ionic strength.
2. When suspended in gelatin, tyrosine and cystine crystals adsorb the protein and attain a surface identical in behavior with gelatin-coated quartz or collodion particles.
3. Aluminum ions at low concentrations reduce the electric mobilities of tyrosine crystals to zero in a manner analogous to their effect on other surfaces.
4. Alkyl benzene droplets also have their electric mobility reduced to zero at low pH values but, unlike the amino acids, a change in sign was never noticed.
5. The mobility of tyrosine crystals is independent of crystal length between 2–100µ. Below this size the mobilities are decreased.
6. These results are discussed in connection with the concept of the general definition of the isoelectric point and the behavior of certain insoluble proteins such as wool and silk fibroin.
EXCITATION OF NERVE FIBERS IN THE SQUID (LOLIGO PEALII)
Authors: Prosser C. Ladd , Chambers Alfred H. 
Published: May 2004

1. Strength-duration data for the giant fiber of the great stellar nerve of the squid (Loligo pealii) can be approximately described by several mathematical formulations.
2. Excitation time constants for isolated giant fibers are essentially the same as constants of the giant fibers in the intact nerve.
3. The strength-duration curves of the fibers in the intact nerve lie higher on the voltage axis than those of the isolated fibers. It is concluded that the principal effect of other fibers upon the excitation of one fiber in a nerve trunk is that of shunting the stimulating current.
4. Deterioration of the nerve shifts the curve upward and to the left, resulting in shorter time constants.
5. Decreasing interelectrode distance also shifts the curve upward and to the left.
6. Excitation time constants of the giant fibers are larger with plate electrodes than with wire or pore electrodes.
7. The strength-duration curves of the smaller fin nerve fibers lie consistently to the right of, and the time constants are longer than those of the giant fibers.
PACEMAKERS IN NITELLA
Authors: Osterhout W. J. V. , Hill S. E. 
Published: May 2004

Many forms of irregular rhythm and of partial block occurring in the vertebrate heart can be duplicated in Nitella.
In order to observe these phenomena the cells of Nitella are kept for 6 weeks or more in a nutrient solution. They are then exposed for 3 hours or less to 0.01 M NaCl, NaSCN, or guanidine chloride, which reduce the time required for the action current to about 1 second (the normal time is 15 to 30 seconds).
A pacemaker is established at one end of the cell by placing it in contact with 0.01 M KCl. This produces action currents at the rate of about 1 a second. Apparently some parts of the cell are unable to follow this rapid pace and hence fall into irregular rhythms (arrhythmia) and fail to register all the impulses (partial block).
EFFECT OF SODIUM SULFATE ON THE PHAGE-BACTERIUM REACTION
Authors: Krueger A. P. , Strietmann W. L. 
Published: May 2004

Bacteriophagy taking place in the presence of M/8 Na2SO4 has the following pronounced characteristics:
A. Time of lysis is considerably prolonged.
B. The bacteria take up less than the normal amount of phage.
C. Phage production occurs at one-third the customary rate.
D. It takes four times as much phage to lyse a Na2SO4-treated bacterium than a normal one.
E. Bacterial growth is not affected by Na2SO4.
The lag phase and the lowered rate of phage production can be attributed to the Na2SO4 effect on the cell surface. Less phage is taken up by the cells and contact of phage with the bacterium's precursor-producing mechanism is impeded.
CALCULATIONS OF BIOELECTRIC POTENTIALS
Authors: Osterhout W. J. V. , Hill S. E. 
Published: May 2004

In Nitella the substitution of KCl for NaCl changes the P.D. in a negative direction. In some cases this change is lessened by adding solid CaCl2 to the solution of KCl. This may be due to lessening the partition coefficient of KCl or to decreasing the solubility of an organic substance which sensitizes the cell to the action of KCl.
Little or no correlation exists between this effect of calcium and its ordinary antagonistic action in producing a balanced solution which preserves the life of the cell indefinitely.
CaCl2 is negative to NaCl but positive to KCl.
The effects of mixtures of KCl, NaCl, and CaCl2 are discussed. The concentration effect of a mixture of KCl + CaCl2 shows certain peculiarities due to action currents: these resemble those found with pure KCl.
These studies and others on Nitella, Valonia, and Halicystis indicate that mobilities and partition coefficients are variable and can be brought under experimental control.
BIOELECTRIC POTENTIALS IN HALICYSTIS
Authors: Blinks L. R. , Darsie M. L. , Skow R. K. 
Published: May 2004

The potential difference across the protoplasm of impaled cells of Halicystis is not affected by increase of oxygen tension in equilibrium with the sea water, nor with decrease down to about 1/10 its tension in the air (2 per cent O2 in N2). When bubbling of 2 per cent O2 is stopped, the P.D. drifts downward, to be restored on stirring the sea water, or rebubbling the gas. Bubbling 0.2 per cent O2 causes the P.D. to drop to 20 mv. or less; 1.1 per cent O2 to about 50 mv. Restoration of 2 per cent or higher O2 causes recovery to 70 or 80 mv. often with a preliminary cusp which decreases the P.D. before it rises. Perfusion of aerated sea water through the vacuole is just as effective in restoring the P.D. as external aeration, indicating that the direction of the oxygen gradient is not significant.
Low O2 tension also inhibits the reversed, negative P.D. produced by adding NH4Cl to sea water, 0.2 per cent O2 bringing this P.D. back to the same low positive values found without ammonia. Restoration of 2 per cent O2 or air, restores this latent negativity. At slightly below the threshold for ammonia reversal, low O2 may induce a temporary negativity when first bubbled, and a negative cusp may occur on aeration before positive P.D. is regained. This may be due to a decreased consumption of ammonia, or to intermediate pH changes.
The locus of the P.D. alteration was tested by applying increased KCl concentrations to the cell exterior; the large cusps produced in aerated solutions become greatly decreased when the P.D. has fallen in 0.2 per cent O2. This indicates that the originally high relative mobility or concentration of K+ ion has approached that of Na+ in the external protoplasmic surface under reduced O2 tension. Results obtained with sulfate sea water indicate that Na+ mobility approaches that of SO4— in 0.2 per cent O2. P.D. measurements alone cannot tell whether this is due to an increase of the slower ion or a decrease of the faster ion. A decrease of all ionic permeability is indicated, however, by a greatly increased effective resistance to direct current during low O2. Low resistance is regained on aeration.
The resistance increase resembles that produced by weak acids, cresol, etc. Acids or other substances produced in anaerobiosis may be responsible for the alteration. Or a deficiency of some surface constituent may develop.
In addition to the surface changes there may be alterations in gradients of inorganic or organic ions within the protoplasm, but there is at present no evidence on this point. The surface changes are probably sufficient to account for the phenomena.
THEORY AND MEASUREMENT OF VISUAL MECHANISMS
Authors: Crozier W. J. , Holway A. H. 
Published: May 2004

Monocular threshold stimulus intensities (ΔIo, photons) were measured along the 0–180° meridian of human retinae for three observers. The test image was small (= 0.08°) and of short duration (= 0.20 second). ΔIo was found to decrease as the angular distance from the fovea was increased. Actual counts of the number of retinal elements per mm.2 along the 0–180° meridian (Østerberg) were compared with the obtained results. No direct correlation was found to exist between visual sensitivity and the number of retinal elements.
Binocular threshold stimuli were also measured along the same meridian. The form of the function relating binocular visual sensitivity and retinal position was discovered to be essentially similar to that for monocular sensitivity, but is more symmetrical about the center of the fovea. The magnitude of the binocular measurement is in each case smaller than that of the monocular threshold stimulus intensity for the more sensitive eye. The ratio is statistically equal to 1.4 (a fact which suggests Piper's rule).
These results are shown to be consistent with the hypothesis that the process critical for the eventuation of the threshold response is localized in the central nervous system. They are not consistent with the view that the quantitative properties of visual data are directly determined by properties of the peripheral retina.
THE FLICKER RESPONSE CONTOURS FOR GENETICALLY RELATED FISHES. II
Authors: Crozier W. J. , Wolf Ernst 
Published: May 2004

The flicker response contour has been determined for several species and types of the teleosts Xiphophorus (X.) and Platypoecilius (P.) under the same conditions. The curve (F vs. log Im) is the same for representatives of each generic type, but is different for the two genera. Its duplex nature is analyzable in each instance by application of the probability integral equation to the rod and cone constituent parts. The parameters of this function provide rational measures of invariant properties of the curves, which have specific values according to the genetic constitution of the animal. The F1 hybrids (H'') of X. montezuma x P. variatus show dominance of the X. properties with respect to cone Fmax. and σ' log I, but an intermediate value of the abscissa of inflection (τ'). The rod segment shows dominance of σ' log I from P., but an intermediate value of Fmax. and of τ'. The composite flicker curve involves the operation of two distinct assemblages of excitable elements, differing quantitatively but not qualitatively in physicochemical organization, probably only secondarily related to the histological differentiation of rods and cones because almost certainly of central nervous locus, but following different rules in hereditary determination, and therefore necessarily different in physical organization. The interpretation of the diverse behavior of the three parameters of the probability summation is discussed, particularly in relation to the physical significance of these parameters as revealed by their quantitative relations to temperature, retinal area, and light time fraction in the flash cycle, and to their interrelations in producing the decline of rod effects at higher intensities.
It is stressed that in general the properties of the parameters of a chosen interpretive analytical function must be shown experimentally to possess the physical properties implied by the equation selected before the equation can be regarded as describing those invariant properties of the organic system concerned upon which alone can deduction of the nature of the system proceed. The importance of genetic procedures in furthering demonstration that the biological performance considered in any particular case exhibits constitutionally invariant features provides a potentially powerful instrument in such rational analysis.