bluuebunny/crossref_metadata_2025 huggingface dataset:
SOME ENZYMES OF ISOLATED NUCLEI
Authors: Stern H. , Allfrey V. , Mirsky A. E. , Saetren H.
Published: May 2004

The composition of isolated nuclei and cell preparations from tissues of calf, beef, horse, and fowl was studied with respect to the following components:

1. Liver and kidney arginase, catalase, and uricase; pancreatic lipase and amylase; cardiac muscle myoglobin; erythrocyte hemoglobin; intestinal alkaline phospharase. These are referred to as "special" components in view of their characteristically restricted distribution reflecting the differentiated nature of the tissues in question.

2. Esterase, ß-glucuronidase, alkaline and nucleotide phosphatases, adenosine deaminase, guanase, and nucleoside phosphorylase. These are enzymes of general distribution.

The differences in nuclear composition noted with respect to the "special" components, together with the broad variability in nuclear activity found for enzymes of general distribution, led to the conclusion that nuclei are differentiated structures.

The following distribution was observed:

1. "Special" components: Hemoglobin was found to be present in fowl and goose erythrocyte nuclei, but myoglobin was entirely absent from heart muscle nuclei; of the special enzymes listed, only catalase and arginase appeared to be concentrated in some of the nuclei. There was no significant nuclear concentration of lipase, amylase, uricase, or alkaline phosphatase. No simple relationship was found between the concentration of a special enzyme in a tissue and its activity in the corresponding nuclei. For example, arginase activity, which is high in mammalian liver and in fowl kidney, was found in liver, not kidney, nuclei. Similarly, catalase activity was demonstrated only in mammalian liver nuclei, although, in mammals, both liver and kidney are rich sources of this enzyme.

2. Enzymes of general distribution fell into three classes:

(a) Those present in low concentrations, if at all, in the nuclei—alkaline phosphatase, the nucleotide phosphatases) and ß-glucuronidase.

(b) Those present in nuclei in varying concentrations—esterase.

(c) Those present in high proportions in most nuclei—adenosine deaminase, nucleoside phosphorylase, and guanase. The exceptionally low nuclear activity of intestinal mucosa with respect to these enzymes was discussed in relation to physiological considerations.

The response of nuclei to changes in physiological state was demonstrated by experiments on starvation. The outstanding aspect of this response was a change in nuclear enzymatic activity opposing that observed in the cytoplasm.

A comparison of fetal and adult mucosa cells led to the following tentative interpretation of the observed intracellular enzyme distribution: In cells tending to moribundity, as in those subjected to starvation, relative nuclear enzymatic activity falls.

The occurrence of special enzymes in nuclei was considered in terms of differentiation, and the high nuclear concentration of the nucleoside-specific enzymes was interpreted in terms of general nuclear metabolic activity.
FACTORS AFFECTING THE HEMOLYTIC ACTION OF "LYSOLECITHIN" UPON RABBIT ERYTHROCYTES
Authors: Collier H. Bruce
Published: May 2004

1. Lysolipid was prepared by the action of snake venom on egg yolk, and a study was made of the factors affecting its hemolytic action upon rabbit erythrocytes.

2. Lysis proceeded very rapidly at first, then ceased within a few minutes at room temperature. A given amount of lysin appeared to hemolyze a fixed number of cells, under specified conditions.

3. The more dilute erythrocyte suspensions required relatively more lysin per cell, for 50 per cent hemolysis of the suspension. There may be an equilibrium between the lysin dissolved in the medium and that adsorbed on the cells.

4. The degree of hemolysis for varying lysin concentrations was measured, and the cells showed a typical distribution of resistance to hemolysis.

5. As the temperature was lowered lysis was more extensive. Adsorption of the lysin on the cell surface was apparently increased.

6. The resistance of the erythrocytes to lysis increased slightly as the pH was raised from 5.5 to 7.8.

7. Resistance to lysis was independent of the tonicity of the medium and of initial cell volume. The magnitude of the cell surface was probably the determining factor.

8. A marked shrinkage of the erythrocytes was observed in the presence of calcium ions and lysin, but not in the absence of the lysin.

9. Hemolytic resistance curves obtained by the Wilbrandt technique were of the "colloid-osmotic" type. However, there was no evidence of prolytic loss of potassium ions.

10. Hypotonic fragility of the cells was slightly increased in the presence of the lysin. The rate of penetration of thiourea was greatly increased.
THE INCORPORATION OF N15-GLYCINE BY AVIAN ERYTHROCYTES AND RETICULOCYTES IN VITRO
Authors: Allfrey V. , Mirsky A. E.
Published: May 2004

A study of the incorporation of glycine-N15 by chicken red cells in vitro has shown that:

1. There is no detectable nitrogen turnover in the histone or desoxyribonucleic acid of erythrocytes or reticulocytes.

2. Hemoglobin synthesis in the nucleated reticulocyte proceeds at 2 to 3 times the rate observed in the mature erythrocyte.

3. The uptake of glycine-N15 by heme is 9 to 14 times the corresponding uptake into hemoglobin, and 12 to 20 times the calculated uptake into globin.

4. Maturation of the red cell results in a decline in the rate of synthesis of both heme and globin, but the deceleration is much more marked in globin. synthesis.

5. No significant differences could be detected in the low N15 incorporations of nuclear and cytoplasmic hemoglobins.
THE B. MYCOIDES N HOST-VIRUS SYSTEM
Authors: Baer B. S. , Krueger A. P.
Published: May 2004

There were differences in the way the lysogenic strain N of B. mycoides and the parent indicator strain grew on nutrient agar and in nutrient broth.

1. On agar, the indicator culture traveled more quickly over the agar surface than the phage-carrying strain; the total extent of spread was greater.

2. In broth, the indicator strain grew diffusely throughout the liquid, the lysogenic cells in clumps. The virus-infected strain appeared to grow more slowly. This may reflect (a) the effect of aggregation on the generation time of the lysogenic strain, (b) an active lytic process in the lysogenic population which is further enhanced by the effect of clump formation on the environment of the cell.
STUDIES ON THE MECHANISM OF ACTION OF IONIZING RADIATIONS
Authors: Barron E. S. Guzman , Seki S. Louise
Published: May 2004

On x-irradiation of the eggs and sperm of Arbacia punctulata there was inhibition of respiration with relatively large doses, whereas there was an increase with small doses. The dose required to produce an increase of respiration depended on the degree of sensitivity of the cell to the effect of ionizing radiation. Sperm cells were more sensitive; then came fertilized eggs; unfertilized eggs were the least sensitive. The inhibiting effect of x-rays on cell division was observed even on irradiation with x-ray doses which produced an increase of respiration. These results are compared to similar effects produced by thiol reagents and are attributed to oxidation of the thiol compounds in the cell.
THE B. MYCOIDES N HOST-VIRUS SYSTEM
Authors: Baer B. S. , Krueger A. P.
Published: May 2004

In nutrient broth at 30 to 32°C., the cycle of virus growth (following adsorption) in lag phase cells of B. mycoides N included a period of intracellular multiplication, ranging from 0.8 to 1.3 hours, succeeded by a sharp rise in the free phage titer and then by a slower rise or a plateau in the extracellular phage content. The yield of virus per infected cell at 30°C., as determined by a modified Burnet dilution technique, was about 76 plaque-forming particles.

During the latent period, multiply infected cells showed no change in numbers. Coinciding with phage release, incomplete clearing occurred. The unlysed, remaining cells multiplied and the turbidity rose again. These survivors and their progeny were lysogenic.
THE B. MYCOIDES N HOST-VIRUS SYSTEM
Authors: Baer B. S. , Krueger A. P.
Published: May 2004

Experiments were performed to determine the mechanism of release of phage from the lysogenic strain of B. mycoides N. The results suggest that qualitatively the same situation obtains as in the phage-carrying cultures of B. megatherium 899 and E. coli Li; i.e., the population consists of two kinds of cells: "lysogènes potentiels" and "producteurs." Quantitatively, however, there are more "producers" in a broth culture of the lysogenic B. mycoides N, at least curing the first 4 to 8 hours after cells have been suspended in fresh medium, suggesting that the interaction between host and parasite is one in which the balance is easily swung in favor of the virus.

These conclusions are based upon the following lines of evidence: (1) the slow "growth rate" of the lysogenic culture, (2) the fact that the colony count falls far below the plaque count or the filament count (which correspond) for a well washed suspension, (3) the increase in phage output in a large number of tubes, each containing a small number of lysogenic cells, after a few hours' incubation in nutrient broth at 30°C.
A STUDY ON THE STRUCTURAL PROTEIN OF THE VITREOUS BODY (VITROSIN)
Authors: Matoltsy A. Gedeon
Published: May 2004

A method is described for the isolation of a structural protein of the vitreous body, which has been named vitrosin. The analyses show that vitrosin is a viscous, thixotropic, fibrous protein. Electron micrographs reveal that vitrosin particles are long fibrils, averaging 250 A in width. The isoelectric point was found to be around pH 5.5 and the shrinkage temperature 60°C. Vitrosin is composed of a protein-carbohydrate complex. It contains cystine and the aromatic amino acids in low quantities. Hexosamine could not be detected in the complex.
THE PERMEABILITY OF THE HUMAN ERYTHROCYTE TO SODIUM AND POTASSIUM
Authors: Solomon A. K.
Published: May 2004

Measurements have been made on the permeability of the human erythrocyte to Na and K in vitro, using radioactive tracers to observe the system in the steady state. The average inward K flux is 1.67 m.eq./liter cells hour, and the apparent activation energy is 12,300 ± 1300 calories/mol. The inward K flux is independent of the external K concentration in the range of concentrations studied (4 to 16 m.eq. K/liter plasma). Rb appears to compete with K for transport into the cell, whereas Na and Li do not. The average inward Na flux is 3.08 ± 0.57 m.eq. Na/liter cells hour, and the apparent activation energies are 20,200 ± 2700 calories/mol for inward transport, and 14,900 ± 3,400 calories/mol for outward transport. The inward Na flux is dependent on the external Na concentration, but not in a linear fashion. Li appears to compete with Na for inward transport, whereas K and Rb do not.

An approximate maximum estimate shows that the energy required for cation transport is only 8.8 calories/mol liter cells hour of the 110 calories/mol liter cells hour available from the consumption of glucose. A working hypothesis for the transport of Na and K is presented.
CONTRACTILE PROPERTIES OF COMPRESSED MONOLAYERS OF ACTOMYOSIN
Authors: Hayashi Teru
Published: May 2004

1. Surface-spread actomyosin, compressed into fibers, shows biological properties of contractility and enzymic activity.

2. In unloaded contractions, wet and dry weight determinations show no appreciable water loss in contraction. The fibers also evince a strong ATP-ase activity.

3. A structural continuity in the fibers by intermolecular linkages of the component actomyosin molecules is established during the formation of the fibers. Evidence includes their visible longitudinal structural organization, the lack of elongation effect of ATP when under tension, and their ability to lift appreciable loads, so that, like muscle, they can transform chemical energy into mechanical work.

4. Up to a limiting critical weight, the fibers perform more work with increasing imposed weight load.

5. Theoretical aspects are discussed, including the possibility that surface-spread protein is involved in the formation of cell structures. Possible explanations for the relative slowness of the fiber contractions are offered.
THE ISOLATION OF WHEAT GERM NUCLEI AND SOME ASPECTS OF THEIR GLYCOLYTIC METABOLISM
Authors: Stern H. , Mirsky A. E.
Published: May 2004

1. A procedure for isolating nuclei of the wheat germ in non-aqueous media has been described.

2. Such nuclei were shown to constitute about 50 per cent of the protoplasmic mass and to have a ribonucleic acid content of an order equivalent to that of the cytoplasm.

3. Studies of the distribution of the enzymes—aldolase, phosphoglyceraldehyde dehydrogenase, enolase, and pyruvate kinase—have revealed that the nuclei are the most vigorous sites of glycolytic activity.

4. Analysis of the DPN content of the nuclei in calf tissues—liver, pancreas, and heart—pointed to the probability that glycolytic activity is a characteristic common to many nuclei.

5. The significance of glycolytic activity to nuclear function has been discussed and some suggestive comparisons made between the two energy-yielding systems of glycolytic and oxidative phosphorylation.
SOME ASPECTS OF THE DESOXYRIBONUCLEASE ACTIVITIES OF ANIMAL TISSUES
Authors: Allfrey V. , Mirsky A. E.
Published: May 2004

It has been found that many animal tissues contain "acid" desoxyribonucleases with pH optima near 5.2. A chemical method for the determination of this activity is described.

The pancreatic desoxyribonuclease crystallized by Kunitz and shown to have a neutral pH optimum occurs in the pancreas together with the "acid" enzyme, but only the "neutral" enzyme occurs in the pancreatic juice. The ratio of "neutral" to "acid" DNAase activities in the pancreas is greater than 200, but in all other tissues examined there is no appreciable concentration of the neutral enzyme. It is concluded that neutral DNAase, like trypsin or lipase, has a digestive function. Some problems in the activation of the secretory enzyme in neutral pancreatic extracts are described. This activation can be interpreted in terms of a specific inhibitor or an inactive form of the enzyme.

A comparison of the "acid" DNAase activities of different organs of the calf, horse, chicken, mouse, and rat indicates a possible connection between the DNAase concentration of a tissue and its capacity for proliferation or regeneration. However, the comparative DNAase activities of fetal and adult tissues do not support the view that DNAase function is limited to some simple role in the mechanics of cell division.

Studies on the incorporation of glycine-N15 into the desoxypentose nucleic acids of avian red cells, and mouse liver, pancreas, and kidney show that the N15 uptake into the DNA of the chromosome is most rapid in tissues with high DNAase concentrations. No N15 incorporation is observed in the DNA of avian red cells, which have negligible concentrations of the enzyme.

The analyses of tissues and nuclei isolated in non-aqueous media show that the bulk of the enzyme occurs in the cytoplasm of the cell, and that nuclear concentrations vary from tissue to tissue. A theory relating the DNAase activity of the cell to its over-all desoxypentose nucleotide metabolism is discussed.

No evidence has been found for the presence of inhibitors of the "acid" DNAase in animal tissues.
NUTRITION OF THE EUROPEAN CORN BORER, PYRAUSTA NUBILALIS (HBN.)
Authors: Beck Stanley D.
Published: May 2004

1. The European corn borer larva has been shown to require a dietary source of one or more unidentified factors contained in corn leaves, grass juice concentrate, and certain other plant materials. The required factor or factors has been termed the corn leaf factor.

2. The corn leaf factor does not appear to be identical with any of the known B vitamins, or with ascorbic acid, sodium nucleate, citrovorum factor, or carnitine.

3. The corn leaf factor is heat-stable, acid-stable, water-soluble, and dialyzable.
PROTECTION OF BACTERIOPHAGE AGAINST X-RAYS BY HIGH CONCENTRATIONS OF A NEUTRAL SALT
Authors: Bachofer C. S. , Pottinger M. Aelred
Published: May 2004

Protection of bacteriophage T1 against x-rays was tested in the presence of concentrations of (NH4)2SO4 ranging from 10–6 M to saturation (4.26 M). Survival of T1 in concentrations of 10–6 to 10–3 M after irradiation did not differ significantly from survival in distilled water after irradiation. From 10–3 M to 10–1 M there was a steep rise in survival, with a leveling off as the concentration approached saturation, giving over-all a 2,000-fold increase in survival. The mechanism of salting out protection in these experiments is apparently due chiefly to dehydration, which protects the virus particles against the indirect effects of x-irradiation.

Postirradiation effects, tested by the inactivation of phage added to irradiated media, approach in magnitude the effects obtained by irradiation of the phage particles themselves in the various solutions.

Filter paper adsorption analyses indicate a close correlation between concentrations of (NH4)2SO4, ability of the filter paper to adsorb phage, and protection against x-rays, both during and after irradiation.
INVESTIGATIONS ON THE MITOCHONDRIA OF THE HOUSE FLY, MUSCA DOMESTICA L
Authors: Sacktor Bertram
Published: May 2004

1. The ATPase activity of insect mitochondria has been investigated. A comparison was made to determine the distribution and nature of such activity in other isolated fractions of the house fly, Musca domestica L.

2. The ATPase in insect mitochondria is specific in that orthophosphate can be cleaved only from ATP. The Michaelis-Menten constant K8 = 2.78 x 10–3 M and Vmax. = 76 micrograms P min.–1 mg.–1 dry weight.

3. Mg++ and Mn++ activate this enzymatic reaction in mitochondria, but Ca++ does not. The extent of activation is 60 per cent with the optimal concentration 6 x 10–4 M. Experiments with combinations of Mg++ and Mn++ show that either ion can replace the other and that the effects are additive, depending solely on the final concentration of the combination. Concentrations of Mg, Mn, or Ca ions higher than 6 x 10–3 M inhibit the enzyme.

4. Fluoride does not inhibit the ATPase of insect mitochondria, whereas azide and chloromercuribenzoate do. The per cent inhibition depends on the concentration of inhibitor.

5. Finely dispersed mitochondrial particles have much greater ATPase activity than intact mitochondria. The possible relationship of this observation to latent ATPase is considered.

6. A magnesium-activated adenylate kinase is present in these mitochondria. The liberated orthophosphate, derived from ADP, is the result of the activity of adenylate kinase followed by the specific ATPase.

7. ATP can be dephosphorylated by enzymes found in the muscle fibrils, and in a "soluble" fraction, as well as in mitochondria. The fibrillar ATPase is Ca++-activated. The "soluble" fraction, however, like the mitochondria, is Mg++-activated. The "soluble" ATP dephosphorylation mechanism is distinguished from the mitochondrial ATPase in that it is inhibited by fluoride.

8. The "soluble" fraction also contains a magnesium-activated inorganic pyrophosphatase. Fluoride completely inhibits this enzymatic reaction.

9. The possible mechanism of ATP dephosphorylation in the "soluble" fraction is discussed.
THE RELATIONSHIP OF SODIUM UPTAKE, POTASSIUM REJECTION, AND SKIN POTENTIAL IN ISOLATED FROG SKIN
Authors: Huf Ernst G. , Wills Joyce
Published: May 2004

1. Isolated surviving frog skin, when bathed with the same kind of diluted Ringer's solution on both sides, shows a negative correlation between net active salt uptake by the epithelium and spontaneous skin potential. Average values of 0.15 to 0.86 µeq. x hr.–1 x cm.–2 were measured and correlated with average skin potentials ranging from 107 to 25 mv.

2. Sodium uptake exceeded chloride uptake by about the same amount, irrespective of the height of the skin potential.

3. The same skins which exhibited a negative correlation between net uptake of sodium chloride and skin potential showed a positive correlation between net potassium rejection from the epithelium and skin potential, for voltages above 30 to 40 mv. In skins of voltages lower than this, potassium ions were taken up rather than rejected. Average values for rejection of +11.8 to –0.8 centi-µeq. x hr.–1 x cm.–2 were measured.

4. Net fluid uptake, associated with active uptake of sodium chloride, was small and occurred in the direction of the salt uptake. No dependence of net fluid uptake upon skin potential was observed.

5. Skins of winter frogs, pretreated with a commercial purified ACTH preparation, were less active than their respective controls with regard to uptake of sodium chloride. Rejection of potassium was the same in treated and untreated skins. Posterior pituitary factors, as possible contaminants, did not account for the effect of the ACTH preparation.

6. DOCA, DOC, and cortisone did not alter the normal correlation referred to under (1) and (3).

7. In interpreting the experimental results on theoretical grounds, it is suggested (a) that in normal skin, it is the variation in the electric conductance in skin of chloride ions which essentially, although not exclusively, determines the rate of net uptake of sodium chloride, (b) that a factor in the ACTH preparation used, possibly ACTH itself, may have lowered the electric conductance in skin of sodium ions either truly or apparently, (c) that potassium ions are treated by the skin primarily as passive ions. There is some indication that potassium ions are also actively taken up by the epithelium of skin.
TIME COURSE AND QUANTUM EFFICIENCY OF PHOTOSYNTHESIS IN CHLORELLA
Authors: Brackett Frederick S. , Olson Rodney A. , Crickard Robert G.
Published: May 2004

1. Though the quantum yield remains constant for different samples of the same culture despite great changes in respiration due to dark adaptation, the quantum requirement for different cultures varies from 6.1 to 13.5 quanta per molecule of oxygen evolved (q/m).

2. This variation from one culture to another appears to depend upon chlorophyll concentration, though other paralleling factors cannot be ruled out.

3. Both chlorophyll concentration and quantum requirement show a random distribution. A statistical median for 50 cultures and 99 determinations gives q/m = 8.5 with a systematic uncertainty of perhaps 10 per cent. Since the variations are real, the median is regarded as less important than the lower limit approached (about q/m = 6).

4. Dark adaptation under aerobic conditions produces an initial photosynthetic rate of nearly zero. The immediate rise to steady state is somewhat logarithmic in character and may require over 3 minutes.

5. In intermittent light (of periods from 1 to 6 minutes) the induction observed in subsequent light periods starts from a finite initial rate and occupies a shorter time, often as little as 30 seconds.

6. The theoretical importance of aerobic induction is discussed. A chlorophyll cycle of two photochemical steps is found to satisfy most of the observed characteristics and to be compatible with an efficiency independent of intensity.
AFTER-POTENTIAL OF SPINAL AXONS IN VIVO
Authors: Rudin Donald O. , Eisenman George
Published: May 2004

A method is evolved whereby the after-potential sequence intrinsic to longitudinal dorsal column myelinated fibers may be studied in isolation from those events occurring in intact spinal cord subjected to an afferent volley.

The recovery sequence intrinsic to dorsal column fibers, after refractoriness is over, is characterized by supernormality approximately four to five times greater than that seen in peripheral nerve. This supemormality averages 15.7 ± 4 per cent (current calibration) at peak and decays exponentially with a half-time of 7.5 msecs. It is not followed by subnormality unless conditioning is repeated more than three times at frequencies greater than 100/sec.

Characterization of the recovery curve of dorsal column fibers permits by exclusion, the allocation of the origin of DRV to structures more centrally located.

DCV (the dorsal column counterpart of DRV) is seen to exist equally developed in active and passive dorsal column fibers.
THE KINETICS OF PROGRESSIVE REACTIONS IN SYSTEMS CONTAINING SAPONIN, DIGITONIN, AND SODIUM TAUROCHOLATE
Authors: Ponder Eric
Published: May 2004

The relations between lysin concentration, percentage hemolysis at the moment at which the lysin concentration is reduced by dilution, and the amount of hemolysis which follows the dilution as a result of the reaction being "progressive" point to there being an "internal" phase at the red cell surfaces, in which the lysin is less affected by the dilution than in the system as a whole. A second possibility, i.e. that the combination of lysin molecules with certain components of the cell surface has an ultimate effect on neighboring components which depend on the former for their stability cannot, however, be ruled out.

In systems containing digitonin or sodium taurocholate, this internal phase, once formed, seems to be almost unaffected by the dilution of the system; i.e., these lysins are very firmly held at the cell surfaces. In systems containing saponin the lysin is less firmly attached, so that dilution of the system affects its concentration appreciably.
AUTOMATIC RECORDING OF THE GROWTH RATES OF CONTINUOUSLY CULTURED MICROORGANISMS
Authors: Anderson Paul A.
Published: May 2004

A procedure which establishes steady states in cultures of microorganisms and also provides continuous automatic recording of their growth rates is described.
A STUDY OF THE FLUID UPTAKE OF RAT KIDNEY SLICES IN VITRO
Authors: Deyrup Ingrith
Published: May 2004

Rat renal cortical and medullary tissues show a marked elevation of relative water content when immersed in "physiological solutions" containing sodium and chloride ions, or in equally concentrated solutions of monosaccharides. In contrast to this, no increase in relative water content occurs in isosmotic solutions of three disaccharides studied. It appears to be unlikely that the fluid uptake is a result of intracellular hypertonicity existing either physiologically or pathologically. A more satisfactory alternative hypothesis is that ingress of water accompanies entrance of solutes (ions, monosaccharide molecules) into the tissue cells.
NUCLEIC ACID ECONOMY IN BACTERIA INFECTED WITH BACTERIOPHAGE T2
Authors: Hershey A. D. , Dixon June , Chase Martha
Published: May 2004

1. The phosphorus content per infective particle of isolated bacteriophage T2 has been redetermined. It does not exceed 1.8 to 2.2 x 10–11 µg. The equivalent amount of DNA has been defined in terms of several analytical methods and taken as a unit of measurement of intrabacterial DNA.

2. The DNA of E. coli contains guanine, adenine, cytosine, and thymine in approximately equal amounts, but no hydroxymethylcytosine. One bacterial cell contains 40 to 150 units of DNA, depending on the conditions of growth and the method of measurement.

3. The DNA of phage T2 (one unit per particle by definition) contains guanine, 5-hydroxymethylcytosine, and relatively large amounts of adenine and thymine, but no cytosine.

4. Infected bacteria contain DNA of a composition that varies systematically during the course of viral growth. At all times it resembles a mixture of bacterial and viral DNA.

5. The characteristic bacterial DNA is decomposed after infection, measuring about one-third its initial amount at 20 minutes. The characteristic viral DNA increases in amount, after a short delay, reaching a level of 100 to 400 units per bacterium 30 minutes after infection. At 10 minutes after infection, the two kinds of DNA are approximately equal in amount.

6. The characteristic viral DNA present in infected cells exists in two forms, one consisting of infective particles and one not. The portion not contained in infective particles builds up to 40 to 80 units per cell during the first 10 minutes after infection and afterwards remains roughly constant in amount. Infective particles begin to appear at 10 minutes and account for all or most of the increase thereafter.
THE EFFECTS OF TOBACCO MOSAIC VIRUS SYNTHESIS ON THE FREE AMINO ACID AND AMIDE COMPOSITION OF THE HOST
Authors: Commoner Barry , Nehari Varda
Published: May 2004

1. Changes in concentrations of free amino acids and amides have been determined in TMV-infected tobacco leaf discs and in comparable uninfected discs during the time of virus formation.

2. During the period of rapid virus formation the infected discs show a transitory deficiency (as compared to uninfected discs) in glutamine, asparagine, aspartic acid, glutamic acid, serine, and to a lesser extent in valine, threonine, and proline. About 100 hours before this time smaller deficiencies in the concentrations of these components also occur. The latter effect is probably associated with the early synthesis of a non-virus protein in infected tissue.

3. Comparison of the above effects with the known amino acid composition of TMV indicates that it is unlikely that the virus protein is synthesized by condensation of appropriate free amino acids. Rather, the deficiencies observed appear to result from removal of ammonia from the nitrogen pool during synthesis of new proteins in infected tissue. Equilibrium shifts resulting from ammonia withdrawal probably account for the observed deficiencies in amides and free amino acids. TMV protein, therefore, appears to be synthesized de novo, from non-protein nitrogen, probably ammonia.

4. It is suggested that the changes in free amino acid concentrations induced by virus formation may account for some of the symptoms observed in infected plants.
INHIBITION OF LACTIC STREPTOCOCCUS BACTERIOPHAGE BY CRYSTAL VIOLET AND OTHER AGENTS
Authors: Graham D. M. , Nelson F. E.
Published: May 2004

Ninety-nine selected compounds and eleven antibiotic-producing organisms were tested for antiphage activity and host toxicity. A paper disc-agar diffusion method was used for primary screening and quantitative methods were employed for confirmatory investigation. Most of the agents tested, although previously reported as inhibitory to one or more other virus-host systems, did not selectively prevent multiplication of lactic streptococcus bacteriophage. Several compounds which prevented mass lysis were extremely toxic to host bacteria.

Crystal violet suppressed growth of two phage strains at a level (1.0 x 10–7 M) which permitted normal growth of the host cells. Failure of crystal violet to prevent multiplication of many phage strains suggested possible variations in the multiplication mechanisms of different strains of virus. Virustatic levels of crystal violet did not destroy unadsorbed virus, reduce adsorption, or prevent invasion; increase of virus was reduced in one-step growth experiments; mass lysis was prevented or delayed in long time experiments. Addition and removal of crystal violet at various intervals during the latent period resulted in virus yields directly related to the portion of the latent period during which no dye was present. Duration of the latent period was unaffected. Single burst experiments indicated that the yield of plaque-forming particles per infected bacterium was reduced; the proportion of infected bacteria giving rise to active progeny did not appear to be influenced to a significant degree. Crystal violet apparently interferes with intracellular multiplication of the virus, possibly by combination of the dye with phage DNA or fractions thereof at some critical stage in the incorporation of DNA into the virus particle.
THE CONTROL OF ENERGY RELEASE IN EXTRACTED MUSCLE FIBERS
Authors: Bozler Emil , Prince J. T.
Published: May 2004

Tension and P liberation were determined at the same time in glycerol-extracted muscle fibers suspended in ATP solutions. In the relaxed state, produced by ATP in rather fresh preparations, P liberation was low, but somewhat higher than in normal resting muscle. On addition of small amounts of CaCl2 the fibers gave a strong contraction during which P liberation was on the average about 5 times higher than in the relaxed condition. In aged muscle fibers ATP always produced a strong contraction associated with a high ATPase activity which was not influenced by Ca. The P liberation during a sustained contraction was much smaller in extracted fibers than in normal muscle, but the former maintained tension much more economically than the latter, resembling smooth muscle in this respect. Also the removal of Mg caused a contraction associated with high ATPase activity. Mg, therefore, is inhibitory in relaxed fibers. In fibers activated by Ca or by aging, however, it caused enhancement. The effects of ions on ATPase activity of relaxed fibers are similar to those on myosin and dissociated actomyosin, whereas activated fibers resemble actomyosin at low salt concentration.
MITOCHONDRIA IN THE FLIGHT MUSCLES OF INSECTS
Authors: Watanabe Mary Ishimoto , Williams Carroll M.
Published: May 2004

1. The sarcosomes of Drosophila and the blowfly, Phormia, are dense, spherical, homogeneous bodies when isolated from flight muscle and promptly examined under the phase contrast, oil immersion objective.

2. Their average diameter in newly emerged flies is about 1 µ. This value increases rapidly during the 1st week of adult life and then becomes constant at approximately 2.5 µ. At each age the variation in sarcosome diameter conforms approximately to a normal distribution.

3. The degree to which isolated sarcosomes retain their initial size and organization is remarkably conditioned by the composition and the hydrogen ion concentration of the medium in which they are teased and suspended. In suboptimal media three major categories of change were encountered: (1) swelling, with or without compaction of the contents (as in distilled water and salt solutions); (2) shrinkage to rod-like, pleomorphic forms (as in blood serum); and (3) fuzzy degeneration (as in sugar solutions).

4. The membrane that surrounds each sarcosome becomes plainly visible in swollen sarcosomes. A continuation of swelling is accompanied by the escape of the sarcosomal contents, the vacated membrane persisting as a spherical, optically empty ghost.

5. Sarcosomes appear to behave like osmometers when suspended in various aqueous solutions. Solutes which penetrate the membrane show only transient effects in preventing the osmotic entry of water.

6. Under this analysis we find the membrane to be more or less freely permeable to the ions of sodium, potassium, calcium, magnesium, chloride, and phosphate, to non-electrolytes smaller than hexoses, to phosphorylated hexoses, and to several intermediates of the citric acid cycle.

7. The sarcosomal membrane appears to be less permeable to non-electrolytes larger than pentoses, provided that such molecules are not phosphorylated.

8. The membrane shows a higher permeability to ATP than to ADP. The significance of this observation is considered with respect to the ADP-ATP shuttle between sarcosomes and muscle fibrils.

9. Simple solutions of electrolytes or non-electrolytes cause more or less conspicuous changes in the microscopic appearance of sarcosomes. Prolonged preservation was achieved only in more complicated media containing protein. It is concluded that the Donnan equilibrium is the source of the principal osmotic forces regulating the movement of water through the sarcosomal membrane.

10. The optimal medium for the preservation of isolated sarcosomes was an intracellular Ringer solution containing 2.5 per cent crystalline bovine albumin in 0.16 M potassium phosphate buffer at pH 7.0.
MECHANISMS OF BIOELECTRIC ACTIVITY IN ELECTRIC TISSUE
Authors: Altamirano Mario , Coates Christopher W. , Grundfest Harry , Nachmansohn David
Published: May 2004

1. A preparation is described consisting of one or several layers of innervated cells of the electric organ of Electrophorus electricus.

2. Each plaque is multiply innervated and only at its caudal face. The nerve fibers may derive from two or more different nerve trunks.

3. During activity the innervated face becomes negative relative to the non-innervated.

4. The first electrical response of the cell to an increasing neural volley is graded and has the character of a prepotential. At a critical size of the prepotential the cell discharges with an all-or-nothing spike.

5. Both responses have durations of about 2 msec.

6. A neural volley which does not cause the spike discharge facilitates the discharge of the cell by a second subsequent volley in the same nerve (temporal facilitation).

7. The period of facilitation lasts ca. 900 msec. During the first 100 msec., the facilitation is large enough to cause a spike. In the later portion only the prepotential is facilitated. No electrical concomitant has been detected.

8. Neural volleys reaching the plaque from different trunks interact at the cell to produce a period of facilitation lasting only about 2 msec. This interaction is interpreted as spatial summation.

9. In a population of cells, simultaneous stimulation of 2 nerves causes a smaller discharge than the sum of the two isolated responses (occlusion).

10. Cells denervated for 7 weeks or more can be excited directly, but only by a current flow outward through the caudal face.

11. Weak direct stimulation causes a prepotential in the denervated plaque. On increasing the stimulus the prepotential increases to a critical size when a spike develops. The duration of both responses is about 2 msec.

12. The absolutely refractory period of the denervated cell is about 1.5 msec. and relative refractoriness lasts about 15 msec.

13. Direct stimulation causes slight facilitation lasting as long as 200 msec.

14. Repetitive stimulation of the nerve at low frequencies (2 to 3 per second) causes rapid "fatigue" of transmission. The denervated plaque, however, responds for several minutes to repetitive direct stimulation at high frequencies (25 per second).
QUANTUM RELATIONS IN PHOTOREACTIVATION OF COLPIDIUM
Authors: Giese A. C. , Iverson R. M. , Shepard D. C. , Jacobson C. , Brandt C. L.
Published: May 2004

1. The amount of visible or long ultraviolet light (UV) required to photoreactivate Colpidium colpoda injured with known dosages of short UV (2654 A) was determined.

2. The effect of the short UV was tested by the delay in division of exposed animals compared to controls. Photoreactivation was tested by the effect of postillumination on the delay of division of treated colpidia compared to controls.

3. Colpidia were used in two physiological states: well fed and starved in balanced medium for 48 hours. The latter are much more sensitive to short UV although less susceptible of photoreactivation.

4. Photoreactivation occurred over the entire span from 3350 A to 4350 A for the well fed colpidia, from 3130 A to 5490 (green) for starved colpidia.

5. The photoreactivating effect of a single quantum of blue (4350 A) or long UV (3660 A) delivered per quantum of 2654 A used to injure colpidia was too slight to be considered significant. The effect of 10 quanta was usually more pronounced, but only after 100 quanta had been delivered was the photoreactivation nearly maximal for well fed colpidia.

6. The quantum requirement for maximal photoreactivation of the starved animals was greater at all wave lengths tried: 3660, 4050, 4350, and 5460 A being of the order of 800 incident quanta per incident quantum of 2654 A.

7. The transmission of UV(2654 A), blue, yellow, and red light by a suspension of colpidia was determined.

8. Large dosages of blue, violet, or long UV were slightly injurious to starved colpidia. In a few cases large dosages of 3660 A killed starved colpidia, especially after a non-lethal dose of short UV(2654 A).

9. Photoreactivation seems to be a balance between the slight injurious effect produced by the visible light or UV of long wave lengths and the injury produced by short wave length UV.

10. Possible reasons for the large number of quanta of photoreactivating light required per quantum of short UV are discussed.
SOME PROPERTIES OF A PHOTODYNAMIC PIGMENT FROM BLEPHARISMA
Authors: Giese Arthur C.
Published: May 2004

1. A pigment can be extracted from Blepharisma undulans by heat treatment of a concentrated suspension of the deeply pigmented animals.

2. In the presence of this pigment, various colorless protozoans are sensitized to light and killed if exposed long enough. The protozoans show a differential sensitivity, some being much more sensitive than others.

3. Bleached colorless blepharismas are not sensitized to their own pigment even after prolonged exposure in the most concentrated solutions available.

4. Blepharisma is also less sensitive than any of the protozoans tested to such photodynamic dyes as rose bengal.

5. The pigment is not extracted from wet blepharismas by non-polar solvents, but is readily extracted into such polar organic solvents as the alcohols.

6. When the alcohol extract is dried, the amorphous residue is readily soluble in a variety of organic solvents, but not in the most non-polar.

7. The pigment is highly stable in alcohol extract and has been kept in the dark for years.

8. The pigment is bleached by light in a photooxidation.

9. Absorption maxima are found at wave lengths 5800, 5400, 4800, and 3300 A, the latter being the largest. Similar peaks are found in alcohol and water solutions, although the heights are not exactly the same. In both alcoholic and aqueous solutions pH had an effect on the absorption spectrum. Heat has little effect but illumination with intense visible light or exposure to ultraviolet light bleaches the pigment with decreases in the characteristic peaks.

10. Preliminary absorption column experiments indicate a single pigment in the alcohol extract.

11. Experiments on the migration of zoopurpurin in agar and gelatin gels indicate that it diffuses at about the same rate as eosin and is therefore probably not a large molecule.
PHOTODYNAMIC HEMOLYSIS AT LOW TEMPERATURES
Authors: Blum Harold F. , Kauzmann Elizabeth Flagler
Published: May 2004

It is shown that photodynamic hemolysis may occur at –79°C. if the erythrocytes are suspended in a solution containing 70 per cent glycerol which prevents hemolysis by freezing; but that there is no hemolysis under the same conditions at –210°C. At the higher temperature the viscosity of the solution is still low enough to permit appreciable movement of molecules, whereas at the lower temperature the molecules must be virtually immobile. The findings are compatible with the idea that the dye molecule acts in a cycle, bringing about successive oxidations by O2 molecules, as has been shown for photodynamic hemolysis at room temperature. The assumption of a combination between dye, O2, and substrate does not explain photosensitized hemolysis in the semi-solid state. The mechanism of photosensitized oxidation by O2 is discussed.
THE ODOROUS ATTRACTANT OF THE AMERICAN COCKROACH, PERIPLANETA AMERICANA (L.)
Authors: Wharton D. R. A. , Miller Gail Lorenz , Wharton Martha L.
Published: May 2004

1. Procedures have been developed for studying quantitatively the response of the male American cockroach to the odorous attractant of the female.

2. The percentage of male roaches responding to extracts of the attractant of the female has been found to vary with the log of the concentration of the attractant throughout a wide range.

3. Adaptation to the olfactory stimulus has been demonstrated.

4. A theory of adaptation is offered.
FURTHER STUDIES ON THE FUNCTIONAL PROPERTIES OF SPINAL AXONS IN VIVO
Authors: Eisenman George , Rudin Donald O.
Published: May 2004

Mammalian spinal tracts in situ demonstrate a phase of marked hyperexcitability during hypoxia or on the application of an excess of potassium or citrate ion. This is in keeping with the fact that they also show post-spike supernormality as well as hyperexcitability under cathodal polarization (17). Behavior of this kind indicates that central axons carry a well developed L fraction of membrane properties.

The rhythmic state in central axons in situ, unlike peripheral nerve or spinal root, is not induced by the action of excess potassium ion. This appears to be related to the absence of a positive after-potential in dorsal columns (17).

However, sodium citrate can elicit autonomous firing in central axons. When synchronized by an applied stimulus the resulting periodic oscillations have a fundamental frequency (340 to 400 C.P.S.) which is significantly greater than that of peripheral nerve.
THE ACTION POTENTIAL OF SPINAL AXONS IN VITRO
Authors: Rudin Donald O. , Eisenman George
Published: May 2004

Despite the trauma of dissection and special metabolic requirements, the physiological properties of funiculi of the mammalian spinal cord can be studied in vitro. They are adequately oxygenated by diffusion at 0.88 atm. pO2 and remain in a functionally normal state for over 12 hours.

The internal consistency of several kinds of data presented in this and the foregoing papers (5, 38) serves to characterize certain properties of central myelinated axons whether excised or in situ. (1) Spinal tracts support a large spike potential in vitro whose form, duration, and velocity are comparable to those of alpha fibers in vitro and spinal tracts in vivo. (2) Properties consistent with a large L fraction are found in central axons whether excised or in situ. (3) Following conduction there has been identified post-spike supernormality with exponential time course (7.5 msecs. half-time) which is the result of activity intrinsic to parent fibers of dorsal columns. The supernormality is similar in form and magnitude both in excised and intact funiculi. (4) In excised funiculi the action potential of parent axons includes a large negative after-potential whose form and duration correspond satisfactorily with this supernormality. This potential appears not to result from activity arising in broken collaterals. (5) Central axons, excised or intact, fire spontaneously in the presence of citrate ion, and when synchronized by stimulation develop periodic oscillations at about 400 C.P.S. but show no such behavior in the presence of excess potassium ion.

Certain characteristics peculiar to central axons indicate that they occupy an extreme position in the spectrum of properties encountered in conducting tissues. Dorsal column myelinated axons differ from their peripheral counterparts, even though they are parts of the same cell, in the following ways. The maintenance of the column spike potential is more critically dependent on CO2 and the entire tissue mass has a higher oxygen consumption. The negative after-potential is much larger and the positive after-potential, non-existent following a single volley, is more difficult to develop by repetitive stimulation. Unlike peripheral nerve, central axons are not incited to spontaneous activity by manipulation of certain constituents normally present in their environment. However, when induced by the application of citrate the resulting rhythmic behavior has twice the frequency of that in peripheral nerve. In general, the recovery process in central axons is more invariant than that in peripheral axons when they are subjected to similar changes in their artificial environments.