bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural Studies on Reovirus: Discontinuities in the Genome
Authors: Millward Stewart , Graham Angus F.
Published: May 2006

The double-stranded RNA genome of reovirus breaks reproducibly into ten segments upon extraction from purified virions. Reovirus-induced messenger RNA's formed in infected cells correspond in length to these ten genomic segments and some real structural and biological implication must be accorded to the ready manner in which the genome is fragmented on attempted isolation. In the present work we have posed the question whether the reovirus genome is a continuous, double-stranded molecule or whether there are discontinuities in the complementary strands of RNA that might constitute „weak points” in the structure. To answer this question, a method was developed to estimate the 3′-terminal nucleosides of RNA within intact virions. Approximately as many 3′-ends are free inside the virion as in RNA extracted from purified virus. Thus, the viral genome exists as a discontinuous structure inside the virus particle and both strands of the duplex are interrupted at intervals.
A Differential Equation for an Eisenstein Series of Genus Two
Authors: Resnikoff H. L.
Published: May 2006

A nonlinear differential equation of order 8 satisfied by the Eisenstein series of weight 4 for Siegel's modular group of genus two is presented. This equation plays a role in the theory of modular functions of genus two similar to that played by the differential equation of the Weierstrass [unk]-function associated with elliptic curve.
Origin and Direction of Replication of the Chromosome of
E. coli
B/r
Authors: Masters Millicent
Published: May 2006

The origin and direction of replication of the
E. coli
B/r chromosome has been determined by comparing gene frequencies in P1-transducing lysates prepared on cultures growing at different rates. The gene frequencies found are consistent with the idea that replication of the chromosome is dichotomous in rapidly growing B/r. The origin was found to be between 40 and 55 min on the
E. coli
genetic map with replication proceeding in a clockwise direction. Markers near the origin behaved anomalously.
Surface Movements during the Growth of Single Explanted Neurons
Authors: Bray D.
Published: May 2006

The processes of isolated rat sympathetic neurons growing in culture were marked with glass or carmine particles and observed with timelapse microphotography. Particles on the processes moved with the cell in relation to the dish and underwent continual small jerky movements. They did not, however, show any over-all distal motion and for long periods, during which the growth cone progressed more than 100 μ, the particles remained at about the same distance from the cell body. The most obvious explanation for this result is that new fiber surface, and perhaps the plasma membrane, is deposited in the region of the growing tip.
The Phenomenon of „Vesting” in Ring Chromosomes and Its Role in the Mutation Theory and Understanding of the Mechanism of Crossing-Over
Authors: Dubinin N. P. , Nemtseva L. S.
Published: May 2006

After X-ray irradiation of
Crepis capillaris
dry seeds the authors detected, in addition to usual patterns of chromosome mutations, a new phenomenon of normal rod-shaped chromosomes being „vested,” or encircled, by ring chromosomes. An analysis of the phenomena has demonstrated that the ring-chromosome production is connected with an X-ray-induced formation of a rigid loop by cross-links of different chromosome segments. The repair mechanism seems to cut DNA strands into three fragments at the cross-link site. When the fragment ends brought close together assume a definite position, the middle fragment forms a ring; the rejoined terminal fragments are within this ring which thus vests the chromosome. After DNA synthesis, two sister chromatids are vested by two sister rings. The appearance of different „vesting” patterns is associated with the mitotic crossing-over between sister ring chromatids. At this moment the internal chromatids appear to be capable of slipping out in different combinations from the rings vesting them. It has been shown that the DNA strands are cut into fragments during both the production of chromosome rearrangements and mitotic crossing-over. Due to the effect of chromosome repair cutting, chromosome rearrangements may result from exchange (contact of exchanging chromosomes in a cross-link site) and fragmentation mechanisms when DNA molecules are cut without cross-links or other mechanism assuring contact between different chromosome loci.
Search for Positronium Lyman α-Radiation from Positrons Stopped in Inert Gases
Authors: Leventhal Marvin
Published: May 2006

An attempt to detect the positronium Lyman α-radiation at 2430 Å is reported. Positrons from an intense
64
Cu source (20 Ci) were stopped in high purity A, Ne, and He at pressures ranging from 0.01 to 3.0 atm. Light from the stopping region was collected by a large solid-angle light pipe and directed to a photomultiplier. Spectra were obtained by inserting a series of optical interference filters in front of the photomultiplier. Identical spectra were obtained with an intense electron emitter replacing the
64
Cu source. These results indicate that any Lyman α-radiation present at the photomultiplier is masked by a large background continuum associated with gas excitation processes. The data were employed to set an upper limit of 1 in 2000 on those positrons stopping in the gas which result in Lyman α-radiation.
Isolation of Temperature-Sensitive Mutants of L-Cells
Authors: Thompson L. H. , Mankovitz R. , Baker R. M. , Till J. E. , Siminovitch L. , Whitmore G. F.
Published: May 2006

Procedures are described for the isolation of conditional lethal mutants of mouse L-60T cells. The mutant lines were temperature sensitive by the following criteria: (
a
) colony-forming ability, (
b
) growth in suspension culture, and (
c
) rate of uptake of tritiated-thymidine.
Bacillus subtilis
Mutant Altered in Spore Morphology and in RNA Polymerase Activity
Authors: Doi Roy H. , Brown Lyle R. , Rodgers Gregory , Hsu Yao-pi
Published: May 2006

A
Bacillus subtilis
mutant, that was selected for rifampin resistance produces spores with an altered morphology. The mutant spores are pleomorphic and differ both in shape and size from the wild-type spores. They frequently have an exosporium that is usually absent from wild-type spores. The mutant spores are similar to the wild-type spores in heat resistance, dipicolinic acid content, and density, but exhibit a slower rate of germination, outgrowth, and growth.
In vitro
studies show that the RNA polymerase of the mutant is resistant to rifampin inhibition, whereas the wild-type enzyme is completely inhibited by low concentrations of the antibiotic. Rifampin resistance and the altered spore morphology are contransformed with 100% frequency, suggesting that the altered morphology is caused by an alteration in the RNA polymerase.
Electron Microscopy of Kinetoplastic DNA from
Trypanosoma mega
Authors: Laurent Monique , Steinert M.
Published: May 2006

The electron microscopical aspect of kinetoplast DNA has been studied in preparations obtained by osmotic disruption of isolated organelles. A large amount of this DNA appears to be of large molecular size. This is apparently at variance with the observations, made by others using a different technical approach, of kinetoplast DNA consisting mainly of small circular molecules of constant size. As a homogeneous population of small circles (0.74 μm in contour length) could also be seen in our samples, the possibility that at least two different kinds of DNA exist in the kinetoplast is discussed.
Identification of L-Methionine-
S
-Sulfoximine as the Convulsant Isomer of Methionine Sulfoximine
Authors: Rowe W. Bruce , Meister Alton
Published: May 2006

The convulsant agent methionine sulfoximine inhibits brain glutamine synthetase irreversibly and the inhibitor becomes bound to the active site of the enzyme as methionine sulfoximine phosphate. Only one of the four isomers of methionine sulfoximine, L-methionine-
S
-sulfoximine, inhibits glutamine synthetase. In the present work, D-methionine-
SR
-sulfoximine, and highly purified preparations of L-methionine-
S
-sulfoximine and L-methionine-
R
-sulfoximine were tested in mice for convulsant activity; only L-methionine-
S
-sulfoximine produced convulsions. The finding that only one of the four optical isomers of methionine sulfoximine induces convulsions, and that only this same isomer inhibits glutamine synthetase, lends support to the conclusion that these two effects of methionine sulfoximine are closely connected.
Cooperative Effects in Models of Steady-State Transport across Membranes, III. Simulation of Potassium Ion Transport in Nerve
Authors: Hill Terrell L. , Chen Yi-der
Published: May 2006

An extremely simple membrane transport model simulates qualitatively the observed flux-potential curves for steady-state potassium ion transport across a nerve (squid) membrane in the special case of high external potassium ion concentration. The transporting units (protein molecules) in the model are assumed to exist in two different conformations, which interact cooperatively. The membrane potential induces a transition between the two conformations by virtue, primarily, of a polarizability difference in the two conformations. Differential proton binding may make an important contribution to this effect.
Patterned Neural Activity of a Mutant
Drosophila melanogaster
Authors: Ikeda Kazuo , Kaplan William D.
Published: May 2006

Hyperkinetic
1P
, a behavioral mutant of
Drosophila melanogaster
, shows rhythmic leg-shaking action derived from mutation of a single, sex-linked gene. The neural mechanism governing this abnormal motor function consists of rhythmic bursts of activity produced by motor neurons located within the thoracic ganglion. The mechanism of the pattern formation was independent both of sensory information and higher centers in the central nervous system but endogenous within the ganglion. Two types of neurons which appear to be involved in the pattern formation were found within six limited regions.
Membrane Structure: Spin Labeling and Freeze Etching of
Mycoplasma laidlawii
Authors: Tourtellotte Mark E. , Branton Daniel , Keith Alec
Published: May 2006

A spin-labeled fatty acid was incorporated
in vivo
into the polar lipids of
Mycoplasma laidlawii
membranes. The electron paramagnetic resonance signal from either intact cells or their extracted lipids reflected the fatty acid composition of the
Mycoplasma
membranes. Comparison of signals from intact cells, gramicidin-treated cells, heat-treated cells, and extracted lipids indicates that a major portion of the membrane lipids is in a semiviscous hydrocarbon environment. The results also show that the spin label in the intact membrane is slightly but significantly less mobile than it is in protein-free lipid extracts made from these membranes. Correlated electron microscope examinations using the freeze-etch technique reveal particulate components in the hydrophobic region of the membrane. The mobility of the lipids in the intact cell membrane may be influenced by their association with these particles.
PROINSULIN: CRYSTALLIZATION AND PRELIMINARY X-RAY DIFFRACTION STUDIES
Authors: Fullerton W. Wardle , Potter Reginald , Low Barbara W.
Published: May 2006

Bovine proinsulin has been crystallized under a variety of conditions at both neutral and acid pH. Microtechniques were employed with sample weights of about 200 μg and volumes of 5-20 μl. The crystalline preparations all differ from each other morphologically.

X-ray photographs of one form, tetragonal bipyramids grown at pH 3 with added ammonium sulphate solution, established the space group P4
1
2
1
2 (or its enantiomorph P4
3
2
1
2). The cell dimensions are
a
= 50.8 ± 0.2 Å,
c
= 148.0 ± 0.4 Å. The asymmetric unit in this form is a dimer of proinsulin which is also the dominant species in solution at this pH.
Control of Initiation of DNA Synthesis in
Escherichia coli
B/r
Authors: Ward C. B. , Glaser D. A.
Published: May 2006

The pattern of new growing forks in the
Escherichia coli
genome after a period of inhibition of DNA synthesis has been examined. Synchronous cultures of
E. coli
B/r were treated with nalidixic acid to stop DNA synthesis for various lengths of time. After removal of the nalidixic acid the location of active growing forks was determined by measuring the reversion rate of a histidine requirement induced by the „growing-point mutagen,” nitrosoguanidine.

It was found that the ability to initiate a new round of DNA synthesis upon release from the nalidixic acid block was attained at the cell age at which a new round of replication would have been initiated had DNA synthesis not been blocked. However, if the nalidixic acid was removed before the normal initiation age, the initiation of the next round of synthesis was delayed past the normal time, which indicates that initiation of new rounds is not completely independent of DNA synthesis.
Location of the Genes for 16S and 23S Ribosomal RNA in the Genetic Map of
Escherichia coli
Authors: Yu M. T. , Vermeulen C. W. , Atwood K. C.
Published: May 2006

By means of RNA-DNA hybridization with DNA from different merodiploids of
Escherichia coli
, the genes for 16S and 23S ribosomal RNA were found near minute 74 of the genetic map.
Subelliptic Estimates for Complexes
Authors: Guillemin Victor , Sternberg Shlomo
Published: May 2006

New results are announced linking properties of the symbol module and characteristic variety of a differential complex with test estimates near the characteristic variety of the type considered by Hörmander (½-estimate). The first result is the invariance of the test estimates under pseudo-differential change of coordinates, and this leads to the introduction of a normal form for the complex in the neighborhood of a Cohen-MacCauley point of the symbol module. If the characteristic variety V is a manifold near the Cohen-MacCauley point (
x
0
,ζ
0
) with parametrizing functions
p
1
,...,

p
q

, where
q
is the codimension of the characteristic variety in the complexified contangent bundle, the matrix [Formula: see text] of Poisson brackets defines invariantly a Hermitian form
Q
on the normal space to
V
at (
x
0
,ζ
0
) when the
dp
ζ
(
x
0
,ζ
0
) are used as basis, and the test estimates are satisfied at the
i
th stage of the complex if sig.
Q
(signature of
Q
) is ≥
n
-
i
+ 1 (
n
the dimension of the base manifold) or rank
Q
- sig.
Q
≥
i
+ 1. Finally, conditions are given in order that, on a manifold with smooth boundary, the associated boundary complexes satisfy the ½-estimate.
Superconductivity: The Transition Temperature Peak Below Four Electrons per Atom
Authors: Cooper A. S. , Corenzwit E. , Longinotti L. D. , Matthias B. T. , Zachariasen W. H.
Published: May 2006

It is shown that the superconducting transition temperature for compounds in seven different structure types exhibits a peak at about 3.7 to 3.9 valence electrons per atom.
Regulation of Cellular Interferon Production: Enhancement by Antimetabolites
Authors: Tan Y. H. , Armstrong John A. , Ke Y. H. , Ho Monto
Published: May 2006

Cycloheximide, at a protein-inhibitory concentration, when given to rabbit kidney cell cultures that had been exposed either to UV-irradiated Newcastle Disease virus or to a complex of polyinosinic and polycytidylic acids (poly I·poly C), enhanced the production of interferon. The enhancement was greater if, in addition to cycloheximide, the cells were also treated with actinomycin D. On the basis of these findings, a mechanism, consisting primarily of the production of a control protein which normally checks interferon production, is postulated for interferons stimulated by these two substances.
Isolation of γ-L-Glutaminyl 4-Hydroxybenzene and γ-L-Glutaminyl 3,4-Benzoquinone: a Natural Sulfhydryl Reagent, from Sporulating Gill Tissue of the Mushroom
Agaricus bisporus
Authors: Weaver Robert F. , Rajagopalan K. V. , Handler Philip , Jeffs Peter , Byrne William L. , Rosenthal David
Published: May 2006

Early in the development of spores, there appears in gill tissue of the mushroom
Agaricus bisporus
a red pigment that inhibits mitochondrial respiration. The inhibitor and its immediate precursor were isolated from the mushroom and identified as γ-L-glutaminyl 3,4-benzoquinone (I) and γ-L-glutaminyl 4-hydroxybenzene (II), respectively, neither of which had previously been described. II was synthesized chemically and the synthetic material was identical with isolated II in all regards. An enzyme that oxidizes II to I was isolated concurrently. I reacts unusually rapidly, completely, and at low concentration with the sulfhydryl groups of various mitochondrial enzymes, accounting for its originally observed properties. It may also prove of value as a general inhibitor of sulfhydryl-dependent enzymes.
Fluorescent Probes of Biological Membranes
Authors: Waggoner Alan S. , Stryer Lubert
Published: May 2006

Fluorescent and phosphorescent probes that have readily interpretable emission properties can be specifically inserted into biological macromolecules to reveal facets of their structure and dynamics: (1)
Proximity
. Singlet-singlet and triplet-singlet energy transfer can serve as spectroscopic rulers in the 10-65 Å range, whereas triplet-triplet transfer can be used to show that two groups are less than about 12 Å apart. (2)
Rotational mobility
. Nanosecond fluorescence polarization measurements can reveal whether a macromolecular system has any modes of flexibility in times of nanoseconds. (3)
Polarity
. The presence of mobile dipoles in the environment of certain chromophores is reflected in their fluorescence quantum yield and emission spectrum.

We have synthesized a number of new fluorescent probes for biological membranes. Anthroyl stearic acid (I), dansyl phosphatidyl ethanolamine (II), and octadecyl naphthylamine sulfonic acid (III) are readily incorporated into bilayer vesicles composed of phosphatidyl choline. The emission spectra of these probes in the vesicles indicate that the chromophore of I is located in the hydrocarbon region, that of II is located in the glycerol layer, and that of III is located at the aqueous interface of the bilayer. Thus, fluorescent chromophores can be selectively placed in different transverse regions of a model membrane system.
Dopamine as a Synaptic Transmitter and Modulator in Sympathetic Ganglia: A Different Mode of Synaptic Action
Authors: Libet Benjamin , Tosaka Tsuneo
Published: May 2006

An analysis of the role of adrenergic transmission in mediating the hyperpolarizing, slow inhibitory postsynaptic potential has revealed that dopamine is apparently the specific synaptic transmitter for this response. An additional action of dopamine was discovered, namely the selective facilitation of another synaptic response, the slow excitatory postsynaptic potential. (This potential is a depolarizing response to the muscarinic action of acetylcholine.) This second, modulatory, role of dopamine has characteristics strikingly different from other known modes of synaptic action. After a brief initial action by dopamine, the facilitation of the slow excitatory postsynaptic potential response can persist for hours and is unaffected by a delayed blockade of the postsynaptic receptors for dopamine. This suggests that the modulation consists of a long-lasting metabolic and/or structural change induced in the postsynaptic neuron by dopamine.

These conclusions are based on the demonstrated actions of dopamine and other catecholamines, as well as on effects (on dopamine actions and on slow postsynaptic potentials of alpha-adrenergic blockers, of blockade, of dopamine oxidase, of depletion of ganglionic catecholamine by muscarinic excitation, and of a selective re-uptake of dopamine after such depletion.
The π-Cation Radical of Chlorophyll
a
Authors: Borg Donald C. , Fajer Jack , Felton Ronald H. , Dolphin David
Published: May 2006

Chlorophyll
a
undergoes reversible one-electron oxidation in dichloromethane and butyronitrile. Removal of the electron by controlled potential electrolysis or by stoichiometric charge transfer to a known cation radical yields a radical (epr line width = 9 gauss, g = 2.0025 ± 0.0001) whose optical spectrum is bleached relative to that of chlorophyll. Upon electrophoresis this bleached species behaves as a cation. By comparison with the known properties of π-cation radicals of porphyrins and chlorins, the chlorophyll radical is also identified as a π-cation. Further correlation of optical and epr properties with published studies on photosynthesis leads to the conclusion that oxidized P700, the first photochemical product of photosystem I in green plants, contains a π-cation radical of the chlorin component of chlorophyll
a
. This radical is the likely source of the rapidly-decaying, narrow epr signal of photosynthesis.
Tissue Localization of Lymphocytes Bearing a Membrane Receptor for Antigen-Antibody-Complement Complexes
Authors: Dukor Peter , Bianco Celso , Nussenzweig Victor
Published: May 2006

To determine the tissue localization of lymphocytes provisionally termed „complement-receptor lymphocytes,” which are characterized by having a membrane receptor for antigen-antibody-complement complexes, we investigated the adherence of sensitized and nonsensitized sheep red cells to frozen sections of mouse lymphoid organs. Nonsensitized erythrocytes became bound exclusively to sinus-lining cells of spleen and lymph nodes, whereas erythrocytes sensitized with antibody and complement adhered to lymphocytes in the follicular areas and the marginal zone of the spleen and in the true cortex of lymph nodes. However, the doubly sensitized erythrocytes failed to bind to the „thymus-dependent” areas of peripheral lymphoid organs or to the thymus itself. We suggest that complement-receptor lymphocytes are of extrathymic origin and that they contribute substantially to follicular antigen localization, which appears to be complement-dependent.
Proton Nuclear Magnetic Resonance Studies of Myoglobin in H
2
O
Authors: Patel Dinshaw J. , Kampa L. , Shulman R. G. , Yamane T. , Wyluda B. J.
Published: May 2006

Exchangeable hydrogens in proteins can be identified by comparison of nuclear magnetic resonance spectra obtained in H
2
O and in D
2
O. In oxymyoglobin and myoglobin we have been able to observe resonances of the NH protons of the two tryptophans, as well as one resonance from arginine and one from histidine in the range -10 to -15 ppm downfield from 3-(trimethylsilyl)propanesulfonic acid (sodium salt). These resonances have been identified by chemical modifications coupled with considerations of crystallographic structure and the dependence of the resonances on the species (sperm whale, porpoise, horse) from which the myglobin was obtained and on spin, pH, and temperature.
Control of Transcription of the Repressor Gene in Bacteriophage Lambda
Authors: Heinemann Stephen F. , Spiegelman Willard G.
Published: May 2006

The rate of transcription of the structural gene for repressor (
cI
gene) in bacteriophage lambda is controlled by the amount of active repressor in the cell. When the (reversibly) thermolabile repressor in a bacterium lysogenic for λ
cI
857
is inactivated by heat, the rate of repressor gene transcription immediately falls. If the repressor is renatured, synthesis of repressor messenger is immediately restored to a high rate. Control by the repressor of the rate of transcription of its own structural gene does not depend upon the expression of any other known gene because the control can be observed in an
N
-
x
-
lysogen.

Measurement of lambda repressor gene transcription was made possible by a two-step hybridization technique utilizing prehybridization to λ
dv
plasmid DNA. Application of this technique also showed that the product of the
N
gene stimulates transcription of the
r
strand in the region of the
cII
,
O
, and
P
genes.
Evidence from Chloroplast Fragments for Three Photosynthetic Light Reactions
Authors: Arnon Daniel I. , Chain Richard K. , McSwain Berah D. , Tsujimoto Harry Y. , Knaff David B.
Published: May 2006

Previous reports from this laboratory described a new concept of three light reactions in plant photosynthesis comprising two short-wavelength (λ < 700 nm) photoreactions belonging to Photosystem II and one long-wavelength (λ > 700 nm) photoreaction belonging to Photosystem I. Among the electron carriers assigned to Photosystem II were cytochrome
b
559
and plastocyanin and to Photosystem I, cytochrome
f
.

According to a widely held view, the light-induced reduction of NADP by water requires the collaboration of Photosystems I and II and involves specifically cytochrome
f
and P700 (a portion of chlorophyll
a
peculiar to Photosystem I). By contrast, the new concept ascribes the light-induced reduction of NADP by water solely to the two photoreactions of Photosystem II, without the participation of Photosystem I and its components, cytochrome
f
and P700.

Further evidence in support of the new concept has now been obtained from chloroplast fragments. Two kinds of chloroplast fragments have been prepared: (
a
) one with Photosystem II activity, capable—in the presence of plastocyanin—of photoreducing NADP with water but lacking P700 and functional cytochrome
f
and (
b
) another having only Photosystem I activity, lacking plastocyanin, and enriched in P700.
Darboux Problem for a Polyvibrating Equation: Solution as an F-Equation
Authors: Mangeron D. , Oǧuztöreli M. N.
Published: May 2006

In this paper we investigate a Darboux problem for a polyvibrating equation with analytic data. It is solved by the F-function approach of C. Truesdell, extending his F-equations to functions with several variables.
Introduction of a Heterologous Nucleus into Enucleated Cytoplasms of Cultured Mouse L-Cells
Authors: Ladda Roger L. , Estensen Richard D.
Published: May 2006

Mouse L-cells exposed to cytochalasin B undergo random nuclear protrusion and, occasionally, total enucleation. The anucleate cell remains viable for several days. Chick erythrocytes were fused to L-cells with inactivated Sendai virus. The resulting hybrids, containing one or more erythrocyte nuclei in addition to the L-cell nucleus, were treated with cytochalasin B. Through the process of random enucleation, the L-cell nucleus was extruded from some hybrid cells while the erythrocyte nucleus was retained in the hybrid. In other experiments, chick erythrocytes were fused directly to enucleated L-cells. The result in both instances is the introduction of an erythrocyte nucleus into L-cell cytoplasm. The erythrocyte nucleus swells and the hybrid cell is capable of incorporating radioactive uridine.
Current Induced in a Plasma by a Penetrating Electron Beam
Authors: Cox James L. , Thomas L. H.
Published: May 2006

The passage of a single pulse of relativistic electrons through a plasma is considered, and the total current in the axial direction it induces in the plasma is calculated. This calculation is valid for an injected beam current density that has arbitrary functional dependence on the radial and azimuthal coordinates. For the special case of a beam current density that is uniform in the radial direction out to the beam radius a, these results agree with results of others published previously.

This calculation is simple because the equation for the variation with time of the plasma charge density at any point, independent of what happens at other points, is only slightly more complicated than the familiar equation for an ohmic conduction.
Adenosine Triphosphate: Glutamine Synthetase Adenylyltransferase of
Escherichia coli:
Two Active Molecular Forms
Authors: Hennig S. Barbara , Anderson Wayne B. , Ginsburg Ann
Published: May 2006

Two active forms of purified ATP:glutamine synthetase adenylyl-transferase from
Escherichia coli
are apparent on polyacrylamide gel electrophoresis at pH 8. The slower migrating component, which is identical to the P
I
-protein fraction of the glutamine synthetase deadenylylating enzyme system, has
S

20.
w

≅ 5.1 S and a molecular weight of about 130,000. The more rapidly migrating adenylyltransferase component has
S

20.
w

≅ 4.0 S and a molecular weight of about 70,000. During storage at 4°C, the larger adenylyltransferase component (P
I
) converts to the smaller active unit with a concomitant loss of both P
I
deadenylylating activity and soluble protein. It is concluded that the low-molecular weight form of the adenylyltransferase is a subunit of the deadenylylating P
I
-protein.
The N-Terminal Amino Acid Sequence of Two Avian Leukosis Group Specific Antigens
Authors: Niall Hugh D. , Sauer Robert , Allen David W.
Published: May 2006

Two group-specific antigenic proteins from an avian leukosis virus have been compared by amino acid analysis, tryptic peptide fingerprinting, and N-terminal sequence determination, and found to be dissimilar. There was microheterogeneity in the structure of the protein gs-
b
at residues 6; threonine and glutamic acid were found.
Tetrameric Immune Macroglobulins in Three Orders of Bony Fishes
Authors: Acton Ronald T. , Weinheimer Peter F. , Hall Shelby J. , Niedermeier William , Shelton Emma , Bennett J. Claude
Published: May 2006

The immune IgM-like macroglobulins were isolated from three species of bony fishes (
Ictalurus punctatus, Lepisosteus osseus
, and
Polyodon spathula
) representing the three orders of the subclass Actinopterygii. These macroglobulins were found to have sedimentation coefficients of 14 S and molecular weights of 600,000-630,000. The carbohydrate compositions were determined and found to be different from that of human macroglobulins. After reduction and alkylation, the heavy and light chains could be separated by gel filtration and were found to have molecular weights of approximately 70,000 and 23,000 respectively. The amino acid compositions of these chains were similar to those of mammalian IgM heavy and light chains. The macroglobulins were found by electron microscopy to have a tetrameric structure, in contrast to the pentameric structure found in mammalian, chicken, and shark IgM, i.e. in species later on the evolutionary scale.
Lack of Intercellular Suppression of Position-Effect Variegation by Supernumerary Y Chromosomes during Cell Differentiation in
Drosophila melanogaster
Authors: Gearhart John D. , Macintyre Ross J.
Published: May 2006

The objective of this research was to determine whether there is intercellular suppression of position-effect variegation by extra-heterochromatin during cell differentiation (pupation) in
Drosophila melanogaster
. The results provide some indication as to the mechanism and timing for the general suppression of position-effect variegation by supernumerary heterochromatin in the genome. Imaginal discs were excised from larvae having the necessary chromosomal rearrangement required for position-effect variegation and were transplanted into larvae with and without additional Y chromosomes in their genomes. After metamorphosis, the explants were examined to determine the effect of their respective hosts. There were no differences in the extent of variegation between eyes transplanted into hosts carrying different amounts of extra-heterochromatin. Thus, extra-heterochromatin position-effect variegation does not suppress during cell differentiation or, if it does, the action is intracellular.
Modulation of Experimental Renal Dysfunction of Hereditary Fructose Intolerance by Circulating Parathyroid Hormone
Authors: Morris R. Curtis , McSherry Elisabeth , Sebastian Anthony
Published: May 2006

In a woman with hereditary fructose intolerance and intact parathyroid function, the experimental administration of fructose at different dosage schedules invariably induced the dose-dependent, complex dysfunction of the proximal renal tubule now recognized as characteristic. But in a woman with hereditary fructose intolerance and hypoparathyroidism given similar amounts of fructose, the experimental dysfunction was strikingly attenuated or nondemonstrable unless or until fructose and parathyroid hormone were administered in sustained combination. Thereupon, a renal dysfunction of characteristic type and severity occurred invariably and almost immediately. Thus, the concentration of circulating parathyroid hormone can modulate the functional expression of the experimental renal disorder. This effect of parathyroid hormone, which appears to involve more than simple physiologic summation, may have important clinical implications.
DNA Polymerase Activities in Virions of Visna Virus, a Causative Agent of a “Slow” Neurological Disease
Authors: Schlom J. , Harter D. H. , Burny A. , Spiegelman S.
Published: May 2006

The presence is reported of an RNA-instructed DNA polymerase in visna virus, the causative agent of a “slow” neurological disease in sheep. The product synthesized by the RNA-directed reaction has been shown to be a DNA heteropolymer by the following criteria: synthesis requires the presence of all four deoxyriboside triphosphates; the product is resistant to ribonuclease and alkali but is degraded by DNase; and the product has a density of 1.420 in Cs
2
SO
4
solution, characteristic of DNA.

Visna virions, like those of the oncogenic RNA viruses, contain DNA polymerase activities that respond to a variety of double-stranded DNAs and to synthetic DNA·RNA hybrids.
Hypoglycin A: A Specific Inhibitor of Isovaleryl CoA Dehydrogenase
Authors: Tanaka Kay , Miller Edith M. , Isselbacher Kurt J.
Published: May 2006

Evidence is presented for the specific
in vivo
and
in vitro
inhibition of isovaleryl CoA dehydrogenation by hypoglycin A and its derivative, α-ketomethylenecyclopropylpropionic acid. α-Methylbutyryl CoA dehydrogenation was also impaired, but the degree of inhibition was much lower. Isobutyryl CoA dehydrogenation was not inhibited. 4-Pentenoic acid inhibited none of these reactions. It is concluded that isovaleryl CoA is dehydrogenated by a specific enzyme, isovaleryl CoA dehydrogenase, contrary to previous assumptions that it is dehydrogenated by green acyl CoA dehydrogenase. The present concept agrees with our previous findings in isovaleric acidemia, a genetic disorder in which a specific defect of isovaleryl CoA dehydrogenase was observed. It was also demonstrated that isovaleric acidemia can be induced in experimental animals by the administration of hypoglycin A. Furthermore, some symptoms of “the vomiting sickness of Jamaica” appear to be due to isovaleric acid accumulation secondary to the ingestion of hypoglycin A.
Model for Constraint and Control in Biochemical Networks
Authors: Newman Stuart A. , Rice Stuart A.
Published: May 2006

A model is proposed for biochemical networks which takes into account substrate and modifier effects on enzyme activity and the different time scales on which the relevant processes occur. Sources of global constraint that can be utilized in metabolic regulation are indicated, and the relation of the model to the experiments of Kauffman on switching networks is analyzed. The biological significance of the model and possible systems in which it might be tested are discussed.
Catecholamines and the Hydroxylation of Tyrosine in Synaptosomes Isolated from Rat Brain
Authors: Karobath M.
Published: May 2006

Tyrosine hydroxylase activity of synaptosomes isolated from rat brain was examined. A modified tritium-displacement assay was used, which allowed the measurement of tyrosine hydroxylase activity without the addition of either inhibitors of the metabolism of the hydroxylated products or added exogenous cofactor. The enzyme activity was strongly inhibited by the addition of exogenous catecholamines and 3,4-dihydroxy-L-phenyl-alanine. Aromatic amines other than catechols did not markedly influence tyrosine hydroxylase activity. These
in vitro
findings support the hypothesis that synthesis of catecholamines is regulated by a mechanism of end-product inhibition at the tyrosine hydroxylase step.
Quantitative Analysis of Urine Vapor and Breath by Gas-Liquid Partition Chromatography
Authors: Pauling Linus , Robinson Arthur B. , Teranishi Roy , Cary Paul
Published: May 2006

When a human being is placed for several days on a completely defined diet, consisting almost entirely of small molecules that are absorbed from the stomach into the blood, intestinal flora disappear because of lack of nutrition. By this technique, the composition of body fluids can be made constant (standard deviation about 10%) after a few days, permitting significant quantitative analyses to be performed. A method of temperature-programmed gas-liquid partition chromatography has been developed for this purpose. It permits the quantitative determination of about 250 substances in a sample of breath, and of about 280 substances in a sample of urine vapor. The technique should be useful in the application of the principles of orthomolecular medicine.
The Presence and Possible Role of Zinc in RNA Polymerase Obtained from
Escherichia coli
Authors: Scrutton M. C. , Wu C. W. , Goldthwait D. A.
Published: May 2006

Highly purified preparations of the DNA-dependent RNA polymerase obtained from
Escherichia coli
contain about 2 g-atoms of tightly bound zinc per mol (molecular weight 370,000) of enzyme. When the purified enzyme is fractionated on Sephadex G-150 or G-200, correlation is observed between the zinc and enzymic activity. Although some of the preparations examined also contain iron, copper, and magnesium, the content of these metal ions show no consistent correlation with RNA polymerase activity.

Initiation of RNA synthesis is specifically inhibited by 1,10-phenanthroline. Less-effective inhibition is observed for other chelating agents or for a nonchelating phenanthroline analog. The analog also exhibits a pattern of inhibition differing from that characteristic of 1,10-phenanthroline. Binding of purine nucleoside triphosphates at the lower-affinity (

K
d

= 0.15 mM) site may also be prevented by the addition of 1,10-phenanthroline. One or both of the bound zinc atoms may, therefore, participate in the initiation of RNA synthesis.
Similar Idiotypic Specificities in Immunoglobulin Fractions with Different Antibody Functions or Even without Detectable Antibody Function
Authors: Oudin J. , Cazenave P. A.
Published: May 2006

Idiotypy has been studied in antibodies against a protein antigen: hen ovalbumin. Various fractions of antisera to hen ovalbumin have been compared from the standpoint of the idiotypic specificities found on the immunoglobulins that they contain. Idiotypic specificities were found to be common to (
a
) antibodies that were not eluted from the same immunoadsorbent by the same MgCl
2
concentration, but by four different concentrations. (
b
) Antibodies that were precipitable only by hen ovalbumin, only by hen and turkey ovalbumin, or also by duck ovalbumin. (
c
) Antibodies that were precipitated or not precipitated by the homologous ovalbumin, and proteins apparently devoid of antiovalbumin antibody function. These findings are discussed from the standpoint of (
i
) the differences in function between the various fractions with the same idiotypic specificities, and (
ii
) what may be common in the cellular origin of immunoglobulins with a common idiotypic specificity, and what may be different in immunoglobulins with different antibody functions or without antibody function.

The same idiotypic specificities have been found in certain IgG and IgM antiovalbumin antibodies.
Hypothetical Explanations of the Negative Apparent Effects of Cloud Seeding in the Whitetop Experiment
Authors: Lovasich J. L. , Neyman J. , Scott E. L. , Wells M. A.
Published: May 2006

In order to explain the apparent losses of rain ascribable to seeding at the Whitetop trial, particularly large and highly significant in the stratum E (but not in the opposite stratum W) of experimental days, it has been hypothesized that seeding causes widespread cloudiness and subsequent lowering of ground temperatures. This hypothesis is flatly contradicted by the observations: the seeded E-days (but not W-days) were uniformly less cloudy and hotter than those without seeding. Curiously, these differences prevailed not only from the scheduled time of seeding but also for several hours beforehand. The average rainfall for the 10 hr that preceded the time of seeding was investigated in eight “cells”, defined by the day's wind direction to be downwind, upwind, and to the sides and “far” and “near” the center of seeding. Highly significant decreases were found in the far-upwind and far-left cells, indicating an earlymorning disparity between those E-days that later were declared as experimental to be seeded and those E-days that were declared as experimental not to be seeded. This disparity, difficult to explain by chance variation, suggests that particular caution be used in treating differences in the rainfall between seeded and not-seeded days in the Whitetop trial as having been caused by seeding.
Studies on Phosphorylation by Phosphoroguanidinates. The Mechanism of Action of Creatine: ATP Transphosphorylase (Creatine Kinase)
Authors: Haake Paul , Allen Gary W.
Published: May 2006

The solvolyses of phosphorocreatine (creatine phosphate) and models for phosphorocreatine have been investigated and the results are applied to the mechanism of action of creatine kinase (EC 2.7.3.2). A metaphosphate intermediate appears to be involved.
Isolation and Characterization of Myosin and Two Myosin Fragments from Human Blood Platelets
Authors: Adelstein Robert S. , Pollard Thomas D. , Kuehl W. Michael
Published: May 2006

Platelet myosin (thrombosthenin M) and two additional proteins corresponding to the head and rod portion of the myosin molecule have been prepared from human blood platelets. Characterization of these proteins by SDS-polyacrylamide gel electrophoresis, actin binding studies, assay of enzymic ATPase activity, and electron microscopy has shown that the platelet contractile proteins closely resemble the corresponding muscle proteins. Platelet myosin and platelet myosin-head bind to both muscle and platelet actin and have an EDTA + K-stimulated ATPase activity, which is suppressed by Mg
2+
in high salt concentration, whereas platelet rod does not possess either of these properties; platelet myosin and platelet myosin rod aggregate to form thick filaments at low ionic strength. Both intact platelet myosin and myosin head form typical arrowhead-shaped complexes with either platelet or muscle F-actin.
Regulation of Adenosine 3′:5′-Cyclic Monophosphate Concentration in Cultured Human Astrocytoma Cells by Catecholamines and Histamine
Authors: Clark Richard B. , Perkins John P.
Published: May 2006

Norepinephrine, epinephrine, and histamine cause a rapid increase in the concentration of adenosine 3′:5′-cyclic monophosphate (cAMP) in a tumor astrocyte cell line derived from a primary culture of a human glioblastoma multiforme. The catecholamine-induced increase in cAMP is dependent on the cell density, being far greater in cells in the log phase of growth than in cells near terminal density. The response to norepinephrine is inhibited 50% by 0.01 μM propranolol, a blocking agent of β-adrenergic receptors. In contrast, the effect of histamine on cAMP concentration varies only slightly from log-phase growth to terminal density, and is not inhibited by 10 μM propranolol. The results suggest that astrocytoma cells have independent receptors for catecholamines and histamine. Further, if the astrocytoma cell is an adequate model of the normal glial cell, these results suggest that astrocytes in human cerebral cortex may be sensitive to norepinephrine and histamine.
Bifunctional Inhibitors of Pepsin
Authors: Husain S. S. , Ferguson John B. , Fruton Joseph S.
Published: May 2006

Two bifunctional reagents designed to probe the active site of pepsin and other acid proteinases are described. One of these, the bisdiazoketone 1,1-bis(diazoacetyl)-2-phenylethane inactivates pepsin at pH 5.0 much more rapidly than the corresponding monodiazoketon 1-diazoacetyl-2-phenylethane, whereas the other, the bromodiazoketone
dl
-1-diazoacetyl-1-bromo-2-phenylethane is less effective in this regard. The inactivation is greatly accelerated by the presence of Cu(II), and the pH dependence of the process is consistent with the interaction of the enzyme with the metal complex of the carbene derived from the reagent. The bisdiazoketone appears to react stoichiometrically with pepsin in a 1:1 ratio to form a product whose apparent molecular size is the same as that of untreated pepsin. The inactivation of pepsin by the bromodiazoketone is accompanied by the release of stoichiometric amounts of bromide ions and the formation of a major product whose apparent size is similar to that of pepsin, and a minor component larger than the untreated enzyme.
Supraoptic Neurosecretory Neurons of the Guinea Pig in Organ Culture. Biosynthesis of Vasopressin and Neurophysin
Authors: Sachs H. , Goodman R. , Osinchak J. , McKelvy J.
Published: May 2006

Fragments of the anterior hypothalamus that contain supraoptic nuclei and short axonal segments from adult guinea pigs have been kept in organ culture for up to 15 days. Electron micrographs displayed intact nuclei, Nissl substance, Golgi bodies, and an ultrastructure characteristic of viable neurosecretory cells; by contrast, the surrounding neurophil showed extensive degeneration. The cultured hypothalamic tissues of the guinea pig that were pulsed with [
3
H]uridine incorporated label into the RNA of neurosecretory neurons, as determined by radioautography and chemical analysis. Furthermore, and most important, these cells retained a complement of hormones and the ability to incorporate
3
H- and
35
S-labeled amino acids into vasopressin, neurophysin, and other polypeptides. This incorporation was inhibited by either puromycin or cycloheximide.
Dibutyryl Adenosine Cyclic 3′:5′-Monophosphate Effects on Goldfish Behavior and Brain RNA Metabolism
Authors: Shashoua Victor E.
Published: May 2006

Intraventricular administration of dibutyryl adenosine cyclic 3′:5′-monophosphate into goldfish brains produced hyperactive animals. A study of the effects of the drug (25-50 mg/kg) on the incorporation of [5-
3
H] orotic acid, as a precursor of labeled uridine and cytidine, into newly synthesized RNA showed the formation of an RNA with a uridine to cytidine ratio 20-50% higher than that of the control. In double-labeling experiments with uridine as the labeled precursor, the synthesis of a nuclear RNA fraction (not produced in the absence of drug) was demonstrated. Some of this RNA was found to migrate into the cytoplasmic fraction and to become associated with polysomes. The results suggest that cyclic AMP might function as a “metabolic demand signal” for eliciting new RNA synthesis in goldfish brain.
Transformation of Hamster Cells
In Vitro
by Polycyclic Hydrocarbons without Cytotoxicity
Authors: Dipaolo J. A. , Donovan P. J. , Nelson R. L.
Published: May 2006

Treatment with either a flavone or benz(α)anthracene before the addition of a potent carcinogen, benzo(α)pyrene or 3-methylcholanthrene, enhanced the transformation of Syrian hamster cells that are seeded in order to form colonies. 7,8-benzoflavone and benz(α)anthracene prevented the cytotoxicity by the carcinogens, while 5,6-benzoflavone did not. The results clearly indicate that it is possible to dissociate the transforming from the toxic metabolic properties of benzo(α)pyrene and 3-methylcholanthrene.