bluuebunny/crossref_metadata_2025 huggingface dataset:
ARGON, XENON, HYDROGEN, AND THE OXYGEN CONSUMPTION AND GLYCOLYSIS OF MOUSE TISSUE SLICES
Authors: South Frank E. , Cook Sherburne F.
Published: May 2004

The effects of xenon, argon, and hydrogen on the aerobic and anaerobic metabolism of mouse liver, brain, and sarcoma slices have been investigated. Xenon was found to alter the rates of metabolism of these tissues in a manner almost identical with helium. The gas increased the rate of oxygen consumption in all three tissues and significantly depressed that of anaerobic glycolysis in brain and liver. The depression of glycolysis in sarcoma was less pronounced and not highly significant.

Although both the magnitude and statistical significance of the effects observed with argon were much smaller, there was a seeming adherence to the general pattern established by xenon and helium. Hydrogen while remaining essentially ineffective insofar as oxygen uptake was concerned, depressed glycolysis in both liver and brain slices but did not significantly affect sarcoma slices.

The following points are stressed in the Discussion: (1) the magnitude and direction of effects exerted by helium, argon, xenon, hydrogen, and nitrogen do not conform with the relative values of molecular weight, density, and solubility of these gases; (2) the effect of these gases on tissue metabolism does not necessarily parallel that exerted upon the whole organism.
INVESTIGATIONS ON THE MITOCHONDRIA OF THE HOUSEFLY, MUSCA DOMESTICA L
Authors: Sacktor Bertram
Published: May 2004

It has been found that mitochondria isolated from the flight muscle of the housefly, Musca domestica, are capable of effecting oxidative phosphorylation. A systematic investigation of the factors which regulate this coupling was undertaken. It was found:

1. The molarity of the isolation medium had considerable influence on the morphology of the mitochondria. These physical alterations were associated with changes in oxidation, phosphorylation, and ATPase activity.

2. In addition to an optimum isolation medium, the normal morphology of the mitochondria needed to be further stabilized by serum albumin.

3. A "latent" ATPase activity in insect mitochondria was demonstrated. An inverse relationship was found between oxidative phosphorylation and ATPase activity.

4. Oxygen consumption and the uptake of phosphate were linear with respect to time.

5. A respiratory substrate was necessary for phosphorylation and for maintenance of spatially organized mitochondria.

6. No differences in oxygen uptake were found in the presence or absence of inorganic phosphate.

7. Magnesium was required for optimal oxidative phosphorylation. Calcium and manganese inhibited both respiration and phosphorylation.

8. The addition of cytochrome c had no effect on either oxygen or phosphate uptake.

9. ATP, ADP, or AMP were capable of participating in oxidative phosphorylation, but the glucose-hexokinase trapping system was necessary.

10. Fluoride inhibited the phosphorylation of AMP, but increased P/O when ATP was used. This stimulation was not due to the inhibition of ATPase.

11. Neither arginine nor creatine was phosphorylated.

12. The addition of other isolated fractions of flight muscle to the mitochondrial system had no appreciable effect on respiration or phosphorylation.
THE RESPIRATION OF THE ISOLATED ROD OUTER LIMB OF THE FROG RETINA
Authors: Hubbard Ruth
Published: May 2004

The respiration of the isolated frog rod outer limb has been measured in the Cartesian diver. The outer limbs respire in Ringer solution without the addition of substrates, but the rate of respiration is increased by the addition of fructose diphosphate or succinate. The respiration is cyanide-sensitive, and therefore presumably mediated by the cytochromes. The QOO2 in 0.01 M fructose diphosphate is –1.0 µl. oxygen per mg. dry weight per hour at 20°C. This is lower than the QOO2 of whole frog retina, but comparable with it and many other tissues. The respiratory rate is independent of the state of dark adaptation (rhodopsin content) of the outer limbs. The metabolism of the outer limb is probably adequate to provide the DPN required for the maintenance of the rhodopsin concentration necessary for vision.
THE MOLECULAR WEIGHT OF RHODOPSIN AND THE NATURE OF THE RHODOPSIN-DIGITONIN COMPLEX
Authors: Hubbard Ruth
Published: May 2004

The sedimentation behavior of aqueous solutions of digitonin and of cattle rhodopsin in digitonin has been examined in the ultracentrifuge. In confirmation of earlier work, digitonin was found to sediment as a micelle (D-1) with an s20 of about 6.35 Svedberg units, and containing at least 60 molecules. The rhodopsin solutions sediment as a stoichiometric complex of rhodopsin with digitonin (RD-1) with an s20 of about 9.77 Svedberg units. The s20 of the RD-1 micelle is constant between pH 6.3 and 9.6, and in the presence of excess digitonin.

RD-1 travels as a single boundary also in the electrophoresis apparatus at pH 8.5, and on filter paper at pH 8.0. The molecular weight of the RD-1 micelle lies between 260,000 and 290,000. Of this, only about 40,000 gm. are due to rhodopsin; the rest is digitonin (180 to 200 moles).

Comparison of the relative concentrations of RD-1 and retinene in solutions of rhodopsin-digitonin shows that RD-1 contains only one retinene equivalent. It can therefore contain only one molecule of rhodopsin with a molecular weight of about 40,000. Cattle rhodopsin therefore contains only one chromophore consisting of a single molecule of retinene. It is likely that frog rhodopsin has a similar molecular weight and also contains only one chromophore per molecule.

The molar extinction coefficient of rhodopsin is therefore identical with the extinction coefficient per mole of retinene (40,600 cm.2 per mole) and the E(1 per cent, 1 cm., 500 mµ) has a value of about 10.

Rhodopsin constitutes about 14 per cent of the dry weight, and 3.7 per cent of the wet weight of cattle outer limbs. This corresponds to about 4.2 x 106 molecules of rhodopsin per outer limb. The rhodopsin content of frog outer limbs is considerably higher: about 35 per cent of the dry weight, and 10 per cent of the wet weight, corresponding to about 2.1 x 109 molecules per outer limb. Thus the frog outer limb contains about five hundred times as much rhodopsin as the cattle outer limb. But the relative volumes of these structures are such that the ratio of concentrations is only about 2.5 to 1 on a weight basis. Rhodopsin accounts for at least one-fifth of the total protein of the cattle outer limb; for the frog, this value must be higher. The extinction (K500) along its axis is about 0.037 cm.2 for the cattle outer limb, and about 0.50 cm.2 for the frog outer limb.
NON-INVOLVEMENT OF LYSIS DURING SPORULATION OF BACILLUS MYCOIDES IN DISTILLED WATER
Authors: Perry Jerome J. , Foster J. W.
Published: May 2004

Washed vegetative cells of Bacillus mycoides obtained and treated under specified conditions have been found to sporulate when shaken in distilled water under specified conditions. Within limitations of the methods, a heat-resistant cell (spore) is produced for each heat-sensitive vegetative cell present initially. Several different experiments designed to detect massive lysis and cell growth during sporulation in distilled water yielded uniformly negative results. Evidence is furnished for the conclusion that a freshly formed spore (heat-resistant cell) weighs considerably less than its progenitor vegetative cell. The observed results are most satisfactorily explained as a direct conversion of a vegetative cell to a spore.
THE ODOROUS ATTRACTANT OF THE AMERICAN COCKROACH, PERIPLANETA AMERICANA (L.)
Authors: Wharton D. R. A. , Miller Gail Lorenz , Wharton Martha L.
Published: May 2004

A method has been developed for the assay of the odorous attractant of the cockroach, P. americana. The method, called the counterpoint test, employs two matched groups of roaches and provides for a simultaneous titration of standard and unknown. It has a statistical error of ±40 per cent at a level of significance of 95 per cent.
EVIDENCE FOR THE PRESENCE OF SEPARATE MECHANISMS REGULATING POTASSIUM AND SODIUM DISTRIBUTION IN ULVA LACTUCA
Authors: Scott George T. , Hayward Hugh R.
Published: May 2004

1. The methods employed in these and preceding (25–27) studies were shown to allow analysis of true cellular sodium and potassium concentrations.

2. The rate of reaccumulation of potassium by potassium-deficient cells is independent of the presence or absence of sodium in the external medium.

3. Phenylurethane (10–3 M), a photosynthetic and metabolic inhibitor, causes a marked progressive loss of potassium and gain of sodium, both of which changes are completely reversible on transferring the samples to running sea water.

4. Iodoacetate, while not effective in causing potassium and sodium shifts in the light, effects a loss of potassium and a gain of sodium in the light in the presence of phenylurethane.

5. Arsenate (5 x 10–3 M) completely protects Ulva against the potassium loss usually observed with iodoacetate in the dark while it affords no protection against the sodium influx under the same conditions. Arsenate given after 18 to 20 hours in iodoacetate gives significant protection against potassium loss in the dark, and allows a slight net reaccumulation of potassium in the light. Arsenate in the dark after iodoacetate affords no protection against the sodium uptake caused by iodoacetate in the dark, while in the light under the same conditions sodium is rapidly secreted to the control level within a few hours. This resecretion of sodium is thought to be primarily an effect of light, the presence of arsenate being incidental.

6. The "decoupling agent" 4,6-dinitro-o-cresol causes a marked progressive increase in cellular sodium and a drop in cellular potassium, though the kinetics of these two movements are distinctly different from each other.

7. Pyruvate (50 mg. per cent) given with iodoacetate (2 x 10–3 M) for 5 hours in the dark completely prevents the sodium increase caused by iodoacetate, while affording less protection against the potassium loss. Phosphoglycerate, on the other hand, offers more protection against potassium loss, and essentially none against the sodium gain.

8. ATP added in small amounts at short intervals to samples maintained in 10–3 M iodoacetate in the dark affords significant protection against the potassium loss observed in iodoacetate. Cellular sodium is somewhat higher in the ATP-iodoacetate samples than in the iodoacetate samples.

9. In the discussion of the data presented two major points are emphasized: (1) the close correlation between cellular metabolism and normal cation control; (2) two mechanisms must be operative in cation regulation in this organism: one for moving potassium inwards and the other for transporting sodium outwards. These mechanisms are independent of each other.
THE COMPOUND ORIGIN OF POTENTIAL IN A STIMULATED DORSAL ROOT
Authors: Eisenman George , Rudin Donald O.
Published: May 2004

The electrotonic potential appearing in a stimulated dorsal root is found to be the resultant of two independent systems of current of different origin.

One component, labelled DRα, is non-occluding.

The other component, labelled DRß, occludes strongly and has the characteristics of the potential which appears in a neighboring unstimulated rootlet (DRIV-V).

Because DRα does not occlude, its origin is assigned to the primary afferent neuron. The result of a general examination of its origin leads to the additional conclusion that it must arise from a physiological spatial gradient in the post-spike recovery cycle of membrane potential along the afferent neuron.

The specific locus of this gradient within the primary neuron is the subject of the succeeding paper (16).
CHANGES IN THE PERMEABILITY OF ASCOSPORES OF NEUROSPORA TETRASPERMA DURING GERMINATION
Authors: Sussman Alfred S.
Published: May 2004

The respiration and germination of activated ascospores of Neurospora tetrasperma have been shown to be almost completely inhibited by concentrations of ethylene diaminetetraacetic acid (EDTA) as low as 0.0035 M. In contrast, however, dormant ascospores are insensitive to this chelating agent. At any time up to about 150 minutes after activation Ca++ or Mg++ can completely reverse this toxicity but Cu++, Co++, and Mn++ only partially reverse it. After this time, the minerals of the Neurospora "minimal" medium taken singly, or in various combinations cannot reverse this effect. Adding EDTA at 120 minutes after activation eliminates the lag period associated with its effect upon respiration. Inhibition occurs even though the cells seem to be impermeable to EDTA. Cationic exchange resins, as another example of a non-penetrating metal-binding agent, gave effects similar to those noted with EDTA. Of the resins used the H+ form of IR-120 and the Na+ and K+ forms of amberlite IRC-50 were the most toxic to activated ascospores. On the other hand, dormant ascospores were entirely unaffected by the resins. The release of Ca++ from activated ascospores coincided with the period of maximum sensitivity to EDTA. More than 60 per cent of the cell's content of K+ is released by EDTA-inhibited ascospores. A low pH decreased the effectiveness of EDTA as a poison. The data are consistent with the possibility that non-penetrating metal-binding agents are toxic because of the irreversible removal of essential cations from the cell. The kinetic data for the inhibitory effects, and for the release of Ca++ establish that the permeability of germinating ascospores to minerals changes drastically as a result of activation.
A THEORY OF TASTE STIMULATION
Authors: Beidler Lloyd M.
Published: May 2004

The treatment in this paper of available quantitative data on the response of taste receptors to sodium salt stimulation clearly indicates that the ions of the chemical stimulus are loosely bound to some substance of the taste receptor. This can be thought of as an initial reaction which ultimately leads to stimulation of the receptor and an eventual depolarization of the associated sensory neuron. The speed of the total reaction suggests that the receptor substance is located on or near the surface of the receptor.

The recently proposed (7) enzymatic reactions for chemoreceptors do not appear plausible for sodium salt stimulation of the taste receptors of the rat.
REVERSIBLE INACTIVATION OF TYPHUS RICKETTSIAE
Authors: Bovarnick Marianna R. , Allen Emma G.
Published: May 2004

Rickettsiae that have been frozen and thawed in isotonic salt solutions show greatly decreased toxicity for mice, hemolytic activity, respiration, and infectivity for eggs. All these properties can be partially restored by incubation of the rickettsiae in the presence of DPN and coenzyme A for 2 hours at 34°C.

The extent of both inactivation and of subsequent reactivation is markedly affected by the presence of low concentrations of sucrose during the process of freezing and thawing.

It has been shown that DPN is present in rickettsial suspensions and that in preparations that have not been frozen, the DPN sediments with the rickettsiae. After freezing in isotonic salt solution the DPN becomes non-sedimentable.
THE ALTERATION OF INTRACELLULAR ENZYMES
Authors: Kaplan J. Gordin ,   With the Assistance of Woon Ki Paik
Published: May 2004

1. The ability of homologous series of alcohols, ketones, and aldehydes to cause alteration of intracellular catalase increases approximately threefold for each methylene group added, thus following Traube's rule. Equiactive concentrations of alcohols (methanol to octanol) varied over a 4,000-fold range, yet the average corresponding surface tension was 42 ± 2 dynes/cm., that for ketones 43 ± 2, and for aldehydes (above C1) 41 ± 3.

2. Above C8 the altering activity of alcohols ceased to follow Traube's rule, and at C18 was nil. Yet the surface activities of alcohols from nonanol to dodecanol did follow Traube's rule. These two facts show that the interface which is being affected by these agents is not the cell surface, for if it were, altering activity should not fall off between C9 and C12 where surface activity is undiminished; they show also that micelle formation by short range association of hydrocarbon "tails," usually invoked to explain decrease in biological activity of compounds above C8, is not responsible for this effect in these experiments, in which permeability of the cell membrane probably is involved.

3. The most soluble alcohols and aldehydes (alcohols C1 to C8; aldehydes C1, C2), but not ketones, cause, above optimal concentration, an irreversible inhibition of yeast catalase.

4. The critical concentration of altering agent (i.e., that concentration just sufficient to cause doubling of the catalase activity of the yeast suspension) was independent of the concentration of the yeast cells.

5. Viability studies show that the number of yeast cells killed by the altering agents was not related to the degree of activation of the catalase produced. While all the cells were invariably killed by concentrations of altering agent which produced complete activation, all the cells had been killed by concentrations which were insufficient to cause more than 50 per cent maximal activation. Further, the evidence suggested that the catalase may be partially activated by concentrations of altering agent which cause no decrease in viability at all. Hence alteration, unlike death, may not be all-or-none per cell.

6. The fact that the biological criterion being examined was the activation of a water-soluble enzyme rules out the possibility that the reason for the logarithmic increase in altering activity with chain length was increase in concentration of the altering agent in some intracellular fat phase. It is concluded that these surface-active agents cause enzyme alteration by becoming adsorbed at some intracellular interface and thus causing, directly or indirectly, the modification of catalase properties.

7. It is considered that these data support, but do not provide critical proof for, the interfacial hypothesis, which states that catalase is present at the intracellular interface in question, but is desorbed into solution as a consequence of the alteration process.
ROLE OF ELECTROLYTES AND STARVATION IN ALTERING APPARENT RADIOSENSITIVITY OF BAKERS' YEAST
Authors: Bair William J. , Stannard J. N.
Published: May 2004

1. Respiration and fermentation of yeast receiving 90,000 r of 250 kv. x-rays were studied under a variety of conditions. This dose will nearly completely inhibit growth or colony formation.

2. The apparent effects of irradiation are quite dependent on the K+ and H+ of the suspending medium. At pH 4.5 stimulatory effects were observed in KH2PO2 buffer and inhibition in potassium-free (T-S-T) buffer. At pH 6.5 the situation was reversed and the effects were very small (about 10 per cent). Addition of K+ to irradiated yeast in T-S-T buffer at pH 4.5 can completely reverse the inhibition seen.

3. Starving increases the apparent radiosensitivity of respiration and fermentation, probably by depletion of metabolite and/or electrolyte reserves.

4. Treatment with a cation exchange resin (dowex 50) results in marked inhibition of these processes in irradiated yeast, either fresh or starved. This was most effective if given after irradiation. Almost complete inhibition of anaerobic CO2 production occurs with starvation, irradiation, and dowex treatment combined.

5. The effects of starvation and cation exchange resin treatment can be reversed, though not completely, by adding K+ to the medium.
EFFECT OF STARVING AND DOWEX 50 TREATMENT ON GROWTH OF NORMAL AND X-IRRADIATED YEAST
Authors: Bair William J. , Stannard J. N.
Published: May 2004

1. Effects of starvation or treatment with a cation exchange resin, dowex 50, parallel in some respects those seen earlier on the respiration and fermentation of bakers' yeast receiving 90,000 r of 250 kv. x-rays. Starvation increased the radiosensitivity of cell division processes whether measured by colony formation or by turbidimetric determination of growth in a liquid medium. The dowex 50 enhanced the radiation effect by the latter measure but appeared to increase colony formation of irradiated yeast.

2. The effects on growth differ from those on respiration and fermentation in that the exchange resin treatment did not inhibit colony formation further, and neither starvation nor resin appreciably altered the growth of non-irradiated yeast.

3. Two effects of radiation are seen in these experiments: (a) a permanent inhibition of growth, and (b) a temporary inhibition of the remaining cells resulting in delay of growth.

4. The irradiated cell is more dependent on certain aspects of its environment in terms of growth responses as well as in terms of metabolism (i.e. respiration and fermentation). Whether or not potassium plays a role in the growth response as it does in the metabolic response cannot be ascertained from the present data.
THE EFFECT OF IODOACETATE AND OTHER INHIBITORS ON PHAGE PRODUCTION AND LYSIS IN THREE PHAGE SYSTEMS
Authors: Baer B. , Shrager S. , Krueger A. P.
Published: May 2004

The minimal bacteriostatic concentration of iodoacetate, azide, or proflavine was added at intervals during the latent periods of virus in three different bacterium-bacteriophage systems (M. aureus, B. mycoides, E. coli). For each interval at which inhibitor was added, the occurrence of lysis and the final yield of phage were determined. In the B. mycoides and E. coli systems, when added during the first part of the latent period, inhibitor prevented lysis and no phage was released. Introduction of inhibitor during the last part of the latent period resulted in normal lysis and in a linear increase in phage that progressively approached the yield obtained in the absence of inhibitor (the later the introduction, the higher the yield). In the M. aureus system, phage production and lysis in the presence of inhibitor followed the same general pattern, except that release of phage and normal lysis occurred in infected cells to which inhibitor had been added quite early in the latent period.

Our results, when compared with those of Foster (1948) with proflavine and Bozeman et al. (1954) with chloramphenicol, suggest that (1) the final phage yields represent the amount of mature intracellular virus present at the time of addition of inhibitor and (2) the reactions leading to lysis proceed independently of those leading to the formation of mature virus once phage infection has reached a critical point in time.
BINDING OF CALCIUM AND MAGNESIUM BY THE CONTRACTILE ELEMENTS
Authors: Bozler Emil
Published: May 2004

Using a technique for determining Ca and Mg based on Schwarzenberg's method of titration with ethylenediamine tetraacetic acid (EDTA), it was found that glycerol-extracted muscle fibers contain on the average 0.58 millimole Ca and 0.55 millimole Mg per kg. muscle. The fibers take up additional Ca or Mg from dilute solutions of these metals, but in KCl solutions, the excess is exchanged for K ions.

Inorganic pyrophosphate (PP) removes part of the bound Mg, no Ca; EDTA removes predominantly Ca, but never more than about one-half the total amount. These results are discussed in relation to previous observations on the effects of PP and EDTA on mechanical properties and contractility of extracted muscle fibers.

After the partial loss of bound divalent metals, muscle fibers swell in dilute salt solutions; they also contract slightly and become more translucent.
TRANSMITTER POTENTIALITY OF HOMONYMOUS AND HETERONYMOUS MONOSYNAPTIC REFLEX CONNECTIONS OF INDIVIDUAL MOTONEURONS
Authors: Lloyd David P. C. , McIntyre A. K.
Published: May 2004

An assemblage of 110 individual tricipital motoneurons has been examined with the aim of determining those factors that predispose certain motoneurons to heteronymous response in post-tetanic potentiation.

Motoneurons that respond most readily to homonymous volleys are not those that respond most readily to post-tetanically potentiated heteronymous volleys. Hence differences in presynaptic organization rather than differences in mean postsynaptic threshold determine differences in readiness for response.

Every motoneuron exhibits a distinct asymmetry in transmitter potentiality of homonymous and heteronymous monosynaptic reflex connections. The range of transmitter potentialities is wide and that of heteronymous connections to some motoneurons is greater than that of homonymous connections to some other motoneurons.
TEMPORAL FLUCTUATION IN EXCITABILITY OF SPINAL MOTONEURONS AND ITS INFLUENCE ON MONOSYNAPTIC REFLEX RESPONSE
Authors: Hunt Carlton C.
Published: May 2004

Observations on temporal variation in monosynaptic reflex response in the acutely decapitate cat indicate the following:

1. Frequency distribution of response amplitude has a nearly normal form often with some degree of negative skewness. Response variation differs only moderately in form and magnitude from one preparation to another.

2. Temporal variation remains essentially constant at different levels of drive above that level required to complete the zone of variation.

3. The role of response variation in the determination of mean response amplitude is considered.

4. One of the major sources of excitability fluctuation in the "resting" cord is variation in background activity of interneurons.
DECAY OF INCORPORATED RADIOACTIVE PHOSPHORUS DURING REPRODUCTION OF BACTERIOPHAGE T2
Authors: Stent Gunther S.
Published: May 2004

The multiplication of vegetative T2 bacteriophage in B/r bacteria has been followed by studying the lethal effects of decay of incorporated radiophosphorus P32 at various stages of the eclipse period.

Experiment I. Non-radioactive B/r bacteria were infected with highly radioactive (i.e. P32-unstable) T2 and infection allowed to proceed at 37°C. for various numbers of minutes before freezing the infected cells and storing them in liquid nitrogen. The longer development had been allowed to proceed at 37°C. before freezing, the slower the inactivation of the frozen infective centers by P32 decay. Samples which were frozen after incubation for 9 minutes were completely stable.

Experiment II. Radioactive B/r bacteria in radioactive growth medium were infected with non-radioactive (i.e. stable) T2 and incubated for various lengths of time before being frozen and stored in liquid nitrogen, like those of Experiment I. In this case, the infective centers were stable to P32 decay as long as they were frozen before the end of the eclipse period. The T2 progeny phages issuing from the infected bacteria were P32-unstable.

Experiment III. Radioactive B/r bacteria in radioactive medium were infected with radioactive (i.e. P32-unstable) T2 and otherwise incubated and frozen like those of the first two experiments. In this case, the same progressive stabilization, of the infective centers towards inactivation by P32 decay was observed as that found in Experiment I. The ability to yield infective progeny of infected bacteria incubated for 10 minutes at 37°C. before freezing could no longer be destroyed by P32 decay. The progeny issuing from the infected cells were as unstable as the parental phage.

These results could be explained by one of three general hypotheses. As vegetative phage begins to multiply, it is possible that: (a) there is a high probability that any part of the vegetative phage already duplicated can be saved after its destruction by P32 decay through a process analogous to multiplicity reactivation or, (b) there occurs a change in state of the deoxyribonucleic acid (DNA) preliminary to or in the course of its replication that renders it refractory to destruction by P32 decay, or, finally (c) there occurs a transfer of the genetic factors from the DNA of the infecting phage to another substance not sensitive to destruction by P32 decay.
SYNAPTIC INHIBITION IN AN ISOLATED NERVE CELL
Authors: Kuffler Stephen W. , Eyzaguirre Carlos
Published: May 2004

Following the preceding studies on the mechanisms of excitation in stretch receptor cells of crayfish, this investigation analyzes inhibitory activity in the synapses formed by two neurons. The cell body of the receptor neuron is located in the periphery and sends dendrites into a fine muscle strand. The dendrites receive innervation through an accessory nerve fiber which has now been established to be inhibitory. There exists a direct peripheral inhibitory control mechanism which can modulate the activity of the stretch receptor. The receptor cell which can be studied in isolation was stimulated by stretch deformation of its dendrites or by antidromic excitation and the effect of inhibitory impulses on its activity was analyzed. Recording was done mainly with intracellular leads inserted into the cell body.

1. Stimulation of the relatively slowly conducting inhibitory nerve fiber either decreases the afferent discharge rate or stops impulses altogether in stretched receptor cells. The inhibitory action is confined to the dendrites and acts on the generator mechanism which is set up by stretch deformation. By restricting depolarization of the dendrites above a certain level, inhibition prevents the generator potential from attaining the "firing level" of the cell.

2. The same inhibitory impulse may set up a postsynaptic polarization or a depolarization, depending on the resting potential level of the cell. The membrane potential at which the inhibitory synaptic potential reverses its polarity, the equilibrium level, may vary in different preparations. The inhibitory potentials increase as the resting potential is displaced in any direction from the inhibitory equilibrium.

3. The inhibitory potentials usually rise to a peak in about 2 msec. and decay in about 30 msec. After repetitive inhibitory stimulation a delayed secondary polarization phase has frequently been seen, prolonging the inhibitory action. Repetitive inhibitory excitation may also be followed by a period of facilitation. Some examples of "direct" excitation by the depolarizing action of inhibitory impulses are described.

4. The interaction between antidromic and inhibitory impulses was studied. The results support previous conclusions (a) that during stretch the dendrites provide a persisting "drive" for the more central portions of the receptor cell, and (b) that antidromic all-or-none impulses do not penetrate into the distal portions of stretch-depolarized dendrites. The "after-potentials" of antidromic impulses are modified by inhibition.

5. Evidence is presented that inhibitory synaptic activity increases the conductance of the dendrites. This effect may occur in the absence of inhibitory potential changes.
THE EFFECTS OF SICKLING ON ION TRANSPORT
Authors: Tosteson D. C. , Carlsen E. , Dunham E. T.
Published: May 2004

The conversion of red cells of patients with sickle cell anemia (S-S) from biconcave disk to sickle shape by removal of oxygen was found to increase the fraction of medium trapped in cells packed by centrifugation from 0.036 (S.E. 0.003) to 0.106 (S.E. 0.004). The fraction of water in the cells (corrected for trapped medium) was not affected by this shape transformation. Cation transport, however, was changed profoundly. S-S cells incubated in N2 rather than O2 showed net K loss with acceleration of both influx and outflux. That this change in K transport was due to the process of sickling was indicated by (1) the persistence of the effect in the absence of plasma, (2) the absence of the effect in hypoxic S-S cells in which sickling was inhibited by alkali or carbon monoxide, (3) the reversal of the effect when sickling was reversed by exposure to O2, and (4) the independence of the effect from such potentially important factors as age of the cell population. The acceleration of K transport by sickling is probably mediated by modification of the cell surface rather than the cell interior since concentrated sickle hemoglobin solutions in O2 or N2 did not show selective affinity for K. In molecular terms, the effect of sickling on K transport can be explained by presuming that the shape change (1) opens pathways for the free diffusion of K, and (2) accelerates K transport by a non-diffusion carrier process. The evidence for the former mechanism included (a) dependence of K influx into sickled cells on the concentration of K in the medium, and (b) increase in the total cation content of sickled cells with increasing pH. Observations suggestive of a carrier process included (a) the failure of sickled cell K concentration to become equal to external K concentration even after 48 hours, (b) the deviation of the flux ratio from that characteristic of diffusion, and (c) the dependence of K influx on glycolysis.
THE EFFECTS OF SICKLING ON ION TRANSPORT
Authors: Tosteson D. C.
Published: May 2004

When the red cells from patients with sickle cell anemia (S-S) were kept in the disk shape by incubation in O2, they maintained cell sodium in the steady state for at least 10 hours. The sodium flux in such cells at 37°C. was 6.0 ± 1.5 m.eq./ (liters RBC) x (hours).

When S-S cells were sickled by incubation in N2, sodium outflux increased two- to threefold, while influx increased four- to fivefold and the cells gained net sodium. A small but undetermined fraction of the sodium in disk and sickle shaped S-S cells exchanges at one or more rates which are substantially slower than those calculated here from the initial rate of transfer of tracer from cells to the medium.

The penetration of tracer Cs into normal and both disk and sickled S-S cells was markedly inhibited by increasing the K concentration in the medium, indicating that Cs and K compete for an entrance pathway in all three cell types. The ratio of the inward rate constant for tracer Cs to that for K42 in normal and disk-shaped S-S cells increased only slightly when the K concentration in the medium was increased, indicating that almost all the Cs entered such cells in competition with K. Sickling accelerated the entrance of tracer cesium into S-S cells. Furthermore, the rate constant ratio increased with increasing external K concentration in sickled cells, suggesting the simultaneous presence of a non-competitive route for cesium influx in this cell type.

The results are interpreted to support the view that sickling (a) accelerates inward transport of K and Cs and outward transport of Na by a non-diffusion, assumed carrier, process and (b) opens pathways for the diffusion of all three ions.
THE INTERACTIONS OF THE NON-SPECIFIC INHIBITOR OF HYALURONIDASE WITH HYALURONIDASE AND PROTEOLYTIC ENZYMES IN VIVO
Authors: Hadidian Z. , Murphy Marguerite M.
Published: May 2004

1. Following intravenous administration of testes hyaluronidase in rabbits and dogs, there is a decrease in the level of the non-specific inhibitor of hyaluronidase in serum.

2. If a large amount of hyaluronidase is injected, the inhibitor level is reduced to zero and hyaluronidase may be present in serum for some time after the injection. The hyaluronidase activity of such samples of serum increases when the serum is incubated with papain.

3. Hyaluronidase activity is found in the livers of the injected animals in large amounts and this activity is increased considerably when the homogenate of this tissue is incubated with papain.

4. Intravenous administration of several proteases or venom produces a decrease in the serum inhibitor level. Intravenous administration of streptokinase produces such a decrease in rabbits but not in dogs.

5. There is a correlation between the depletion of the inhibitor from the serum and the occurrence of a slow, persistent depression of blood pressure upon administration of proteolytic enzymes.
SYNTHESIS OF PROTEIN IN THE PANCREAS
Authors: Daly M. M. , Allfrey V. G. , Mirsky A. E.
Published: May 2004

The uptake of glycine-N15 into the trypsinogen and chymotrypsinogen of mouse pancreas is much higher than that into any ribonucleoprotein component of the pancreas that has so far been investigated.
THE EFFECT OF TRYPSIN, CHYMOTRYPSIN, RIBONUCLEASE, AND DESOXYRIBONUCLEASE ON ACTIVE, INACTIVE, AND REVERSIBLY INACTIVATED MEGATHERIUM PHAGE
Authors: Northrop John H. ,   With the Technical Assistance of Marie King
Published: May 2004

The effect of trypsin, chymotrypsin, and desoxyribonuclease on active, reversibly inactivated, and heat-inactivated B. megatherium phage, and on living and dead B. megatherium and B. coli has been determined. The results are summarized in Table I.
ANALYSIS OF RESPIRATION DURING GERMINATION AND ENLARGEMENT OF SPORES OF BACILLUS MEGATERIUM AND OF THE FUNGUS MYROTHECIUM VERRUCARIA
Authors: Mandels G. R. , Levinson H. S. , Hyatt M. T.
Published: May 2004

1. There are certainly two, and probably three, stages in the development of B. megaterium from the spore to inception of cell division. The rapid increase in rate of respiration during the initial 10 minutes on glucose-peptone-yeast extract medium coincides with decrease in optical density and with increase in stainability. From about 10 to 100 minutes, the rate increases linearly, coinciding with swelling of the spores and ending at approximately the time of rupture of the spore case. From about 100 to 180 minutes, there is a second and steeper linear increase in respiration rate coinciding with cell elongation. These physiological and morphological phenomena are discussed as criteria for germination.

2. The rate of respiration of M. verrucaria spores also increases linearly up to about 300 minutes in sucrose-yeast extract medium. No breaks in the curves are observed during formation of the germ tubes.

3. Oxygen uptake follows the parabolic curve

See PDF for Equation

within the limits of experimental error for both types of spores.

4. It is postulated that metabolism during these stages of linear increase may be regulated by processes occurring at cellular or intracellular surfaces or by synthesis of a limiting enzyme at constant rate.
OBSERVATIONS ON AN ATP-SENSITIVE PROTEIN SYSTEM FROM THE PLASMODIA OF A MYXOMYCETE
Authors: Ts'o Paul O. P. , Bonner James , Eggman Luther , Vinograd Jerome
Published: May 2004

1. Extracts of the plasmodia of the myxomycete, Physarum polycephalum, exhibit reversible decreases in viscosity in response to the addition of ATP under appropriate conditions. The protoplasm material prepared by extraction with KCl solution can apparently exist in either a high or a low viscosity state. As prepared, it is in the low viscosity condition. Rapid and extensive increases in viscosity of the extract are brought about by addition of AMP, inorganic phosphate, or, under certain conditions, of ATP. Only after the high viscosity state has been attained does addition of appropriate quantities of ATP cause a reversible decrease in viscosity.

2. The active principle of crude plasmodial extracts may be concentrated by fractional precipitation with ammonium sulfate and is found in the fraction precipitated between 30 and 40 per cent saturation. This material possesses a higher viscosity than does the original crude extract and is apparently in the high viscosity state since the addition of ATP causes an immediate reversible decrease in viscosity.

3. The ATP-sensitive fraction of myxomycete plasmodia possesses a viscosity which is dependent upon its previous thermal treatment. Extracts incubated at 0° for a period of a few hours increase greatly in viscosity when they are returned to 24.5°. This increased viscosity is structural in nature, is destroyed by mechanical agitation of the solution, and may be reversibly destroyed by addition of ATP.

4. It is suggested that the ATP-responsive protein of myxomycete plasmodia may be related to sol-gel transformations which have been observed in intact plasmodia and may participate in the protoplasmic streaming of the intact organism. This suggestion is based upon the following facts: (a) the protoplasmic streaming of myxomycete plasmodia is increased by microinjection of ATP; (b) the gel portion of the cytoplasm at the site of the microinjection of ATP is extensively converted to the sol state.

The changes in structure of the intact cytoplasm are thus similar in nature to the changes exhibited in response to ATP by the purified ATP-sensitive protein.

5. The ATP-sensitive protein of myxomycete plasmodia appears to undergo reversible aggregation to form a high viscosity state. The function of ATP is to break down the aggregates thus formed. Since a specific ATPase activity is associated with the purified material, added ATP is gradually destroyed and recovery of viscosity attends the spontaneous reconstitution of aggregates.
INCREASED PHOTOREVERSAL OF ULTRAVIOLET INJURY BY FLASHING LIGHT
Authors: Christensen E. , Giese A. C.
Published: May 2004

1. Photoreversal of ultraviolet (UV) injury was studied in the ciliate protozoan Tetrahymena pyriformis (geleii) strain W, cultured in the absence of other living organisms. The division pattern of progeny of single animals was followed in hanging drop preparations.

2. A sublethal dose of 450 ergs/mm.2 of monochromatic UV of wave length 2654 A produces a lag before the first division followed by a period of cessation of fission after the second division. This cessation sometimes lasts as long as 6 weeks, during which time the animals become smaller and rounder and more opaque. Organisms about to resume division increase in size and transparency; after a few divisions the animals regain their normal division rate.

3. The effect of UV ranging in intensity from 5 to 15 ergs/mm.2/sec. was found to obey the reciprocity law quite well for the UV effect on the division pattern of T. pyriformis. However, the same dose at lower and at higher intensities was less effective.

4. The effect of a dose of UV delivered at high intensity (19 ergs/mm.2/sec.) could be increased by flashing the light, indicating that the system became saturated in the continuous light.

5. A photoreversing dose of monochromatic blue light of wave length 4350 A was found to be more effective when delivered as continuous light at a low intensity, or as intermittent light at a high intensity, rather than as continuous light at the high intensity—indicating that a dark mechanism participates in photoreversal.

6. The time for the dark reaction was determined to be of the order of a few hundredths of a second in experiments in which different lengths of dark period were used while maintaining a constant light period of 0.0025 second.

7. For Colpidium colpoda the efficiency of a given dose of photoreversing light was increased by flashing the light.

8. The present experiments are interpreted in terms of data available in the literature.
APPEARANCE OF NEW PHAGE TYPES AND NEW LYSOGENIC STRAINS AFTER ADAPTATION OF LYSOGENIC B. MEGATHERIUM TO AMMONIUM SULFATE CULTURE MEDIUM
Authors: Northrop John H. , Murphy James S. ,   With the Technical Assistance of Marie King
Published: May 2004

1. Lysogenic B. megatherium 899a was adapted to growth in a minimal ammonium sulfate medium (ASCM).

2. Adaptation took place slowly and the following changes in the culture occurred:

(a) The growth rate increased from 0.5 to 1.5–2.0/hr.

(b) The culture changed from diffuse to mucoid.

(c) The total phage titer, and the gelatinase concentration decreased to 1/100 or less.

(d) The types of phage produced changed from >99 per cent T (wild type) to 30 to 60 per cent miscellaneous clear types. The original T phage was replaced by a different smaller t, never observed in the original 899a culture.

(e) Several new colony types also appeared, but the colony morphology was not correlated with the phage types produced. None of the colony types was stable on repeated transfer either in peptone or ASCM, but continued to disassociate into different colony types (cf. Ivánovics, 1955).

3. Control experiments showed that these changes in phage production and colony types could not be brought about by growing sensitive B. megatherium in the presence of the various new phages, in ASCM. It is therefore unlikely that the changes observed in adapted culture were due to infection of a sensitive cell with phage.

4. Continued growth of the ASCM-adapted strain in peptone resulted in increasing the total phage titer, and also the gelatinase concentration. The growth rate returned to its original value and the ability to grow rapidly in ASCM was soon lost. The phage types, however, remained the same as in the ASCM.

5. An improved cell for steady state growth is described.
THE RELATIONS BETWEEN PREPOTENTIAL, RESTING POTENTIAL, AND LATENT PERIOD IN FROG MUSCLE FIBERS
Authors: Jenerick Howard Peter
Published: May 2004

1. Prepotentials and action potentials were recorded from amphibian striated muscle fibers. Intracellular electrodes were used for stimulating and recording. The resting potential was varied from 55 to 120 mv. by alterations of the KCl concentration of the Ringer's fluid. The magnitude of the prepotential at the initiation of the spike potential was measured and compared to the resting potential and the latent period (time between stimulus "make" and excitation). The magnitude of this prepotential varied with the resting potential.

2. A large prepotential or cathodal depolarization was required to excite a fiber with a high resting potential. If a fiber with a high resting potential fired late (long latency), the adequate prepotential was larger than if the fiber fired early. Fibers with low resting potentials had smaller adequate prepotentials. Also, the adequate prepotential was independent of the latent period, in these depolarized fibers.

3. If the concentration of Ca++ was increased tenfold, the adequate prepotential of depolarized fibers became strongly dependent upon the latency.

4. Fibers with large or normal resting potentials were prone to respond repetitively during the passage of long duration shock, whereas depolarized and Ca++-treated fibers were not.

5. The so-called critical membrane potential (which is defined as the transmembrane potential at the point of excitation) was not independent of the resting potential.
THE EFFECT OF ADENOSINETRIPHOSPHATE UPON ACTOMYOSIN SOLUTIONS, STUDIED WITH A RECORDING DUAL BEAM LIGHT-SCATTERING PHOTOMETER
Authors: Mommaerts W. F. H. M.
Published: May 2004

A recording dual beam light-scattering photometer is described which permits kinetic studies involving changes in turbidity, and which is not, as are single photocell instruments, affected by the errors due to the attenuation of the scattered light within the turbid medium.

With this method, a renewed study has been made of the physical changes occuring in actomyosin under the influence of ATP.
RETINENE ISOMERASE
Authors: Hubbard Ruth
Published: May 2004

Rhodopsin is formed by the condensation of opsin with a cis isomer of retinene, called neo-b. The bleaching of rhodopsin releases all-trans retinene which must be isomerized back to neo-b in order for rhodopsin to regenerate. Both retinene isomers are in equilibrium with the corresponding isomers of vitamin A, through the alcohol dehydrogenase system.

An enzyme is found in cattle retinas and frog pigment layers which catalyzes the interconversion of all-trans and neo-b retinene. We call it "retinene isomerase." It is soluble in neutral phosphate buffer, and precipitates between 20 and 35 per cent saturation with ammonium sulfate.

In the dark, the isomerase converts all-trans and neo-b retinene to an equilibrium mixture of 5 parts neo-b and 95 parts all-trans. With opsin present to trap neo-b, the isomerase catalyzes the synthesis of rhodopsin from all-trans retinene. This reaction, however, is too slow to account for dark adaptation.

Retinene is isomerized by light, but too slowly to supply the retina with neo-b. In aqueous solution the pseudoequilibrium mixture contains about 15 per cent neo-b.

When all-trans retinene is irradiated in the presence of isomerase, the rate of formation of neo-b is increased about 5 times, and the pseudoequilibrium shifted so that the mixture now contains about 32 per cent neo-b.

The isomerase is specific for all-trans and neo-b retinene. It does not act on two other cis isomers of retinene, nor on all-trans or neo-b vitamin A.

The role of the isomerase in vision appears to be as follows: in the light, as rhodopsin is bleached to opsin and all-trans retinene, the latter is in part converted to the neo-b isomer and stored in the pigment epithelium as neo-b vitamin A. During dark adaptation, the dominant process is the trapping by opsin of neo-b retinene supplied from stores of neo-b vitamin A, and the slow isomerase-catalyzed "dark" conversion of all-trans to neo-b retinene.