bluuebunny/crossref_metadata_2025 huggingface dataset:
Susceptibility of Cells from Patients with Primary Immunodeficiency Diseases to Transformation by Simian Virus 40
Authors: Kersey John H. , Gatti Richard A. , Good Robert A. , Aaronson Stuart A. , Todaro George J.
Published: May 2006

Skin fibroblasts were cultured from 15 patients with primary immunodeficiency diseases associated with a high cancer risk, including sex-linked agammaglobulinemia, IgA deficiency, variable immunodeficiency, ataxia-telangiectasia (cerebellar malfunction and abnormalities of blood vessels and immune response), Wiskott-Aldrich syndrome (low platelet count, eczema, and abnormal immune mechanism), and severe combined system (cellular and humoral) immunodeficiency. Fourteen of 15 cell strains were found to have low or regular susceptibility to transformation with the tumor virus, simian virus 40. The data are consistent with the view that the frequent occurrence of malignancy in patients with primary immunodeficiency is due to abnormalities of the immunologic surveillance mechanism.
Inhibition of Sterol Biosynthesis by Bacitracin
Authors: Stone K. John , Strominger Jack L.
Published: May 2006

Bacitracin is an inhibitor of the biosynthesis of squalene and sterols from mevalonic acid, C
5
-isopentenyl pyrophosphate, or C
15
-farnesyl pyrophosphate catalyzed by preparations from rat liver. The antibiotic is active at extremely low ratios of antibiotic to substrate. The mechanism of inhibition appears to be the formation of a complex between bacitracin, divalent cation, and C
15
-farnesyl pyrophosphate and other isoprenyl pyrophosphates. It is similar to the formation of the complex with C
55
-isopropenyl pyrophosphate in microbial systems. The toxicity of bacitracin for animal cells could be due in part to the formation of these complexes.
Caffeic Acid Metabolism by Gnotobiotic Rats and Their Intestinal Bacteria
Authors: Peppercorn Mark A. , Goldman Peter
Published: May 2006

Most metabolites of caffeic acid that are found in the urine of man and experimental animals arise as the result of reactions of the intestinal microflora of the host. This conclusion is now confirmed by the observation that
O
-methylation, which can be attributed to mammalian enzymes, is the only reaction sustained by caffeic acid in germfree rats. When the germfree rats are selectively infected by one or more bacteria characteristic of the gastrointestinal tract of rodents, the feeding of caffeic acid leads to the appearance in the urine of additional metabolites of caffeic acid. The apparent ability of these bacteria in the host to transform caffeic acid does not necessarily correlate with the transformations of caffeic acid that are demonstrable when the same bacteria are cultivated on artificial media.
Protein Polymorphism and Genic Heterozygosity in a Population of the Permanent Translocation Heterozygote,
Oenothera biennis
Authors: Levin Donald A. , Howland Gary P. , Steiner Erich
Published: May 2006

Genic allozyme polymorphism and heterozygosity was studied in a large population of the evening primrose,
Oenothera biennis
, growing in North Haven, Connecticut. This species is a permanent structural heterozygote for the entire complement of 14 chromosomes, and is thus capable of accumulating and maintaining genic heterozygosity. A total of 11 protein species were examined, and these were judged to be controlled by 19 loci. Polymorphism occurs at 26% of the loci, with only two alleles being present at each locus. The proportion of polymorphic loci per population in organisms with normal meiotic systems is no less than in
Oe. biennis
, indicating that structural heterozygosity is not necessarily accompanied by a greater proportion of polymorphic loci. On the other hand, the average
Oe. biennis
was heterozygous at 26% of its loci, an amount considerably greater than in most other organisms. With few exceptions, all plants in the North Haven population had the same genotype. Since the species is a colonizer, it is likely that the population was founded by a single individual and retained this genotype by virtue of the genetic system.
Strand Orientation of Simian Virus 40 Transcription in Productively Infected Cells
Authors: Lindstrom Dona M. , Dulbecco Renato
Published: May 2006

Strand orientation of transcription in BSC-1 cells infected by simian virus 40 (SV40) was investigated by annealing RNAs extracted from infected cells with asymmetric complementary RNA from SV40 DNA synthesized
in vitro
by RNA polymerase from
Escherichia coli
. The results suggest that the early viral RNA sequences (those made before replication of viral DNA) and the late RNA sequences (those synthesized concurrently with replication of viral DNA) are transcribed from opposite strands of the SV40 DNA. The RNA synthesized
in vitro
is of the same polarity as the early
in vivo
RNA and is complementary to the late
in vivo
RNA. Knowledge of strand selection in lytic infection is a step towards understanding the regulation of transcription of this viral DNA.
Excretion of Deoxyribonucleic Acid by Lymphocytes Stimulated with Phytohemagglutinin or Antigen
Authors: Rogers John C. , Boldt David , Kornfeld Stuart , Skinner Sister Ann , Valeri C. Robert
Published: May 2006

When human lymphocytes are cultured in the presence of phytomitogens, 70-90% of the cells undergo blast transformation and synthesize DNA. However, less than 40% of these lymphocytes actually undergo mitosis while 35-90% of the newly synthesized DNA is excreted into the media. The release of DNA by the cells is selective since experiments with [
14
C]uridine indicate that RNA is not lost into the culture media. DNA excretion occurs under many culture conditions. The excreted DNA has an estimated molecular weight of 3 to 12 × 10
6
as determined by gel filtration on Sepharose 2B. It forms a single sharp peak at a density of 1.055 g/cm
3
when examined by sucrose density gradient centrifugation, suggesting that the DNA is complexed to protein or lipid.
Diphenylhydantoin Inhibition of Sodium Conductance in Squid Giant Axon
Authors: Lipicky Raymond J. , Gilbert Daniel L. , Stillman Irving M.
Published: May 2006

Diphenylhydantoin, in concentration of 5-50 μM, decreases the early, transient (sodium) currents of voltage-clamped squid giant axons. These effects are dose-dependent and largely reversible. It appears that diphenylhydantoin reduces the number of open, early, transient (sodium) channels.
Electron Microscope Studies of Heteroduplex DNA from a Deletion Mutant of Bacteriophage ϕX-174
Authors: Kim Jung-Suh , Sharp Phillip A. , Davidson Norman
Published: May 2006

A population of double-stranded replicative form of DNA molecules from bacteriophage ϕX-174 carrying a deletion of about 9% of the wild-type DNA has been discovered in a sample cultivated under conditions where the phage lysozyme gene is nonessential. The structures of deleted monomers, dimers, and trimers were studied by the electron microscope heteroduplex method. The dimers and trimers are head-to-tail repeats of the deleted monomers. Some interesting examples of the dynamical phenomenon of branch migration
in vitro
have been observed in heteroduplexes of deleted dimer and trimer strands with undeleted monomer viral strands from the wild-type phage.
Purification and Properties of Biologically Active Messenger RNA for a Myeloma Light Chain
Authors: Swan D. , Aviv H. , Leder P.
Published: May 2006

A cell-free system derived from Krebs II ascites tumor has been used to assay biologically active mRNA for myeloma (MOPC-41) light chain during its purification by oligothymidylate-cellulose chromatography and sucrose gradient centrifugation. The purified mRNA directs the synthesis of a product that yields tryptic peptides corresponding to those derived from authentic myeloma protein and that forms a specific immunoprecipitate with antibody directed against the MOPC-41 protein. The fact that the light-chain mRNA anneals to oligothymidylic acid-cellulose suggests that it, like several other eukaryotic mRNAs, contains a region rich in adenylic acid residues. The most active fractions of light-chain mRNA, representing about 0.1% of the RNA originally extracted from membrane-bound myeloma polysomes, sediment as a discrete peak with an
s

20,
w

of about 13, roughly corresponding to an RNA molecule containing 850 bases. The results suggest that the light-chain mRNA is monocistronic and that it contains about 200 more bases than would be necessary to encode the variable and constant regions of a single light-chain molecule.
A New Method for the Determination of Biological Quarternary Structure by Neutron Scattering
Authors: Engelman Donald M. , Moore Peter B.
Published: May 2006

Determination of quaternary structure by neutron scattering is proposed. The method gives the identity and relative spatial position of each component of a complex, provided that the complex can be obtained in deuterated form and can be reconstituted from its separated parts. If two components are rich in hydrogen and if the rest of the complex is deuterated, the contrast in scattering power permits the measurement of the separation of the pair from an interference cross term. The structure is obtained by triangulation from a set of measured pair separations.
Inhibition of Methylgalactoside Transport in
Escherichia coli
upon the Cessation of Unsaturated Fatty Acid Biosynthesis
Authors: Robbins April R. , Rotman Boris
Published: May 2006

The activity of the methylgalactoside transport system of
E. coli
is impaired upon treatment with 3-decynoyl-
N
-acetylcysteamine, an inhibitor of unsaturated fatty-acid synthesis. Treated cells are unable to be induced for permease activity, while transport sites synthesized before treatment show a regular loss of activity. The inhibition of methylgalactoside transport occurs at a step after translation of the galactose-binding protein, a component of the permease, and appears to be highly specific, since drug-treated cells show normal viability, protein synthesis, and membrane integrity when transport activity is greatly reduced. A second transport system, the galactoside permease, shows significantly less sensitivity to the inhibitor. That the activity of this permease is maintained in the presence of this inhibitor suggests that the inhibitor does not impair energy coupling.
Proton Magnetic Resonance Comparison of Neurohypophyseal Hormones and Analogs: Deletion of Amino Groups and the Conformation of Lysine Vasopressin
Authors: Glickson J. D. , Urry D. W. , Havran R. T. , Walter Roderich
Published: May 2006

Proton nuclear magnetic resonances of two analogs of the mammalian antidiuretic hormone, lysine vasopressin, have been assigned. The analogs studied were deamino-lysine vasopressin and deamino-8-tosyllysine vasopressin, formally derived from lysine vasopressin by removal of the potential cationic sites. Most assignments made in deuterated dimethylsulfoxide at 220 MHz were directly derived from the already determined spectrum of lysine vasopression in this solvent [Walter
et al., Proc. Nat. Acad. Sci. USA
(1972) 69, 1920]. Comparison of chemical shifts of peptide N
H
peaks, αC
H
-N
H
coupling constants, temperature dependence of peptide N
H
resonances, and proton-deuterium exchange rates revealed that from a conformational standpoint both deamino analogs occupy intermediary positions between lysine vasopressin and oxytocin.
Nuclear Magnetic Resonance Spectrum of Lysine-Vasopressin in Aqueous Solution and Its Structural Implications
Authors: Dreele P. H. Von , Brewster A. I. , Dadok J. , Scheraga H. A. , Bovey F. A. , Ferger M. F. , Vigneaud V. Du
Published: May 2006

The peaks in the proton NMR spectrum of lysine-vasopressin in aqueous solution at pH 3-5 were assigned to particular amino-acid residues by the use of the results of dilution studies and NH-C
α
H and C
α
H-C
β
H decoupling experiments. The conformation of lysine-vasopressin in water differs from its conformation in dimethylsulfoxide.
Spin-Orbital Probes of Biomolecular Structure. A Model DNA-Acridine System
Authors: Galley William C. , Purkey Robert M.
Published: May 2006

Heavy atoms, such as bromine or iodine, perturb the excited-state properties of aromatic chromophores through a spin-orbital coupling mechanism. In the present work the use of specifically directed spin-orbital probes to study subtle structural relationships in biopolymers is described. Heavy atoms are introduced into defined sites in biochemical systems and the emission spectrum of a ligand or intrinsic chromophore is monitored for perturbation by the bound heavy atom. This technique is illustrated by a study of acridine dye binding to the copolymer poly(dA-BrdU). The results are interpreted in terms of an “externally” bound dye fraction whose emission is perturbed by the heavy atom in the polymer and an intercalated dye component unperturbed by bromine.
Induction and Superinduction of Serotonin
N
-Acetyltransferase by Adrenergic Drugs and Denervation in Rat Pineal Organ
Authors: Deguchi Takeo , Axelrod Julius
Published: May 2006

Activity of serotonin
N
-acetyltransferase (EC 2.3.1.5) in rat pineal organ is rapidly and markedly elevated
in vivo
after administration of β-(3,4-dihydroxyphenyl)-L-alanine (L-DOPA), norepinephrine, epinephrine, isoproterenol, monoamine oxidase inhibitors, or theophylline. Serotonin or 5-hydroxytryptophan has no effect on the increase in activity of this enzyme. Inhibitors of protein synthesis or propranolol, a β-adrenergic blocking agent completely inhibit(s) the increase in activity of serotonin
N
-acetyltransferase induced by drugs, indicating that new enzyme molecules are formed via stimulation of β-receptors of pineal cells and adenosine 3′:5′-cyclic monophosphate. When rat pineal organ is denervated by ganglionectomy, β-(3,4-dihydroxyphenyl)-L-alanine induces much more serotonin
N
-acetyltransferase than in the innervated gland. This superinduction by denervation appears to be due to changes of the postsynaptic site, probably the β-adrenergic receptor on the pineal cell.
Entanglement Coupling in Linear Polymers Demonstrated by Networks Crosslinked in States of Strain
Authors: Kramer Ole , Ty Violeta , Ferry John D.
Published: May 2006

Linear 1,2-polybutadiene is crosslinked at 0° by γ-irradiation while strained in simple extension, with extension ratios from 1.3 to 2.0. During irradiation times up to several hours, entanglement slippage is slight, since the temperature is only slightly above the glass transition. Subsequently, samples are released and reach their equilibrium states of ease at room temperature. From the extension ratio at state of ease, the ratio of ν

x

(effective network strands terminated by crosslinks introduced) to ν

N

(effective network strands terminated by entanglements) is calculated by composite network theories of Flory and others; and from the extension ratios together with the modulus, measured at small extensions, ν

N

is calculated explicitly. It appears that ν

x

increases approximately proportional to irradiation time; ν

N

is approximately independent of irradiation, and it corresponds to a molecular weight between effective entanglement loci of about 13,000. This figure, however, which is larger than that deduced from rheological properties of the uncrosslinked polymer, is subject to future downward correction for partial entrapment of the entanglements and other refinements.
Calcium-Regulated Parathyroid Hormone Peptidase
Authors: Fischer Jan A. , Oldham Susan B. , Sizemore Glen W. , Arnaud Claude D.
Published: May 2006

An enzymatic activity that catalyzes the conversion of glandular parathyroid hormone to a smaller-molecular-weight, biologically and immunologically active form of this hormone has been extracted from normal parathyroid and other porcine tissues. The product of the conversion has the immunologic characteristics of the hormone that occurs in peripheral serum and in tissue culture medium from parathyroid explants. The enzyme is activated by chelating agents and is inhibited by high calcium concentrations, suggesting that this enzyme may be important in the regulation of secretion or metabolism of the hormone.
Competitive Binding of Somatomedin to the Insulin Receptors of Adipocytes, Chondrocytes, and Liver Membranes
Authors: Hintz Raymond L. , Clemmons David R. , Underwood Louis E. , Wyk Judson J. Van
Published: May 2006

The action of growth hormone on skeletal tissue is mediated through somatomedin, a low molecular weight peptide found in serum. This peptide, formerly known as “sulfation factor” or “thymidine factor,” produces marked insulin-like effects in various target tissues. Since at least some of the metabolic effects of insulin on target cells are initiated by a highly specific interaction with receptors on cell membranes, this study was undertaken to determine whether somatomedin might interact with the same binding sites. It was found that somatomedin, at physiological concentrations, competes with
125
I-labeled insulin for receptor sites on isolated fat cells, liver membranes, and isolated chondrocytes, and that the relative binding affinities of insulin and somatomedin reflect the
in vitro
biological potencies of the two hormones in these tissues. This is the first demonstration of a peptide other than insulin, proinsulin, or derivatives of insulin competing for insulin-binding sites, and implies a structural, as well as a functional, homology between somatomedin and insulin. Somatomedin may be only one of a larger group of homologous pleiotypic peptides with different target organ specificities.
Study of an Oxygenated Heme Complex in Frozen Solution by Mössbauer Emission Spectroscopy
Authors: Marchant Linda , Sharrock Michael , Hoffman Brian M. , Münck Eckard
Published: May 2006

We have used Mössbauer emission spectroscopy to study an oxygenated heme complex, produced in a frozen solution by nuclear decay from the isomorphous
57
Co-labeled compound. The Mössbauer parameters agree with those obtained by Mössbauer absorption spectroscopy of oxyhemoglobin. Thus, a nonprotein environment for iron can duplicate the unique oxyhemoglobin Mössbauer spectrum. The electronic structure of the heme iron in oxyhemoglobin is not significantly influenced by the protein environment. Mössbauer emission spectroscopy can be useful in the investigation of heme proteins.
Redistribution of Visual Projections in Altered Optic Tecta of Adult Goldfish
Authors: Sharma S. C.
Published: May 2006

The retinotectal connections formed in adult goldfish after removal of the rostro-caudal strip of dorsal tectum were mapped electrophysiologically. Initial maps recorded 1 month after surgery revealed visual scotoma corresponding to the ablated tectum. Subsequent maps recorded 4-5 months after the operation showed that the entire visual field redistributed appropriately over the remaining tectum. It is suggested that, in spite of an abnormal optic tectum, the reformed projection demonstrates a tendency to retain its completeness.
Thiolester Substrates for Transamidating Enzymes: Studies on Fibrinoligase
Authors: Lorand L. , Chou C-H. J. , Simpson I.
Published: May 2006

Esters of thiocholine were shown to inhibit the crosslinking of fibrin clots by the transamidating enzyme, fibrinoligase (thrombin-activated fibrin-stabilizing factor or activated Factor XIII). Inhibition depended on the nature of the acylating group with the phenylpropionyl, phenylbutyryl, and
trans
-cinnamoyl esters being most effective of the compounds tested so far.

Use of the thiolesters made it possible for the first time to study the reactions of fibrinoligase in fully synthetic substrate systems. Enzyme-catalyzed acyl-group transfers from the thiol-esters to a fluorescent amine [
N
-(5-aminopentyl) - 5 - dimethylamino - 1 - naphthalenesulfonamide] could be readily demonstrated and measured.

Trans
-cinnamoylthiocholine reacted with fibrinoligase in a totally calcium-dependent manner in the absence of any added amine, thus providing the first evidence for an esterolytic pathway for this enzyme. Spectral qualities, as well as appreciable extent of solubility in water, would seem to make
trans
-cinnamoylthiocholine a specially suitable substrate for further studies.
Conformally Flat Manifolds
Authors: Kulkarni R. S.
Published: May 2006

This note describes some new examples of conformally flat manifolds, as a step toward a classification of such manifolds up to conformal equivalence.
Relationship of F
lac
Replication and Chromosome Replication
Authors: Cooper Stephen
Published: May 2006

The time of replication of a bacterial plasmid, F
lac
, during the division cycle of
Escherichia coli
has been estimated in exponentially growing cultures and at various times after a shift from minimal medium to a richer medium (a shift-up). There is a variation in the cell age at which the capacity to synthesize β-galactosidase (β-D-galactoside galactohydrolase, EC 3.2.1.23) doubles (assumed to be a measure of the time at which the F
lac
plasmid replicates) when this capacity is measured at various times during the shift-up, and with increasing steady-state exponential growth rate. Cells growing at slow and moderate growth rates exhibit F
lac
replication in the middle of the division cycle. With increasing time after a shift-up or with increasing growth rate the plasmid replicates at earlier times, eventually at cell division, and finally in the older cells. This variation in the cell age at which the plasmid replicates is similar to the variation in cell age at which chromosome initiation occurs during a shift-up, although plasmid replication occurs slightly before initiation of chromosome replication.
The Ear and Hearing in
Bipes biporus
Authors: Wever Ernest Glen , Gans Carl
Published: May 2006

The sound conduction system of
Bipes biporus
is unusual among amphisbaenians, in that the columella does not have a catilaginous or bony extra-columella passing laterally to the labial skin. Instead, the terminal disk of the columella ends in fibrous tissue beneath a deep fold of skin forming the nuchal constriction. The occurrence of an epihyal supports earlier suggestions that the amphisbaenian extracolumella may be homologous to the epihyal.

Measurements of cochlear potentials, made by direction of the sound stimuli to the region of the head posteroventral to the quadrate bone, show that
Bipes biporus
ranks high among amphisbaenians in auditory sensitivity.
Circadian Control of Larval Growth Rate in
Sarcophaga argyrostoma
Authors: Saunders D. S.
Published: May 2006

Larvae of the flesh fly,
Sarcophaga argyrostoma
, were reared in a range of environmental light cycles with periods from 21 to 72 hr, and containing either 12, 14, or 16 hr of white light. The mean length of larval development varied cyclically with the period of the driving light cycle. Protracted development occurred when the larvae were “driven” by light cycles containing a “short day” (12 hr of light) at periods close to their natural circadian frequency (about 24 hr) or multiples thereof. More rapid development occurred when the larvae were “driven” by 24-hr light cycles containing a “long day” (14 or 16 hr of light), or at periods far from their natural frequency (e.g., 36 or 60 hr).
The Nature of the Ground States of Cobalt(II) and Nickel(II) Carboxypeptidase A
Authors: Rosenberg Robert C. , Root Charles A. , Wang Run-Han , Cerdonio Massimo , Gray Harry B.
Published: May 2006

The magnetic susceptibilities of cobalt(II) and nickel(II) derivaties of carboxypeptidase A (CPA) follow the Curie law over a wide temperature range. The observed magnetic moments of Co(II)CPA and Ni(II)CPA are 4.77 ± 0.15 and 2.53 ± 0.10 Bohr Magnetons, respectively. The magnetic and spectral properties of Ni(II)CPA are consistent only with an octahedral ground-state geometry, whereas Co(II)CPA has a probable five-coordinate structure. The results establish ordinary metal-ion ground states for two metallocarboxypeptidase A derivatives which exhibit full peptidase activity.
Estimation of Light-Chain Gene Reiteration of Mouse Immunoglobulin by DNA-RNA Hybridization
Authors: Delovitch T. L. , Baglioni C.
Published: May 2006

A 12S species of RNA has been isolated from membrane-bound polyribosomes of MPC-11 mouse myeloma cells. This 12S RNA is translated by an extract of Krebs-II mouse ascites cells into immunoglobulin light chain. Labeled 12S RNA has been prepared by incubation of myeloma cells with [
3
H]uridine in the presence of low concentrations of actinomycin D and ethidium bromide. This RNA has been hybridized under conditions of DNA excess to mouse myeloma DNA and to liver DNA. A C
0
t
1/2
of about 150 has been obtained, corresponding to a reiteration frequency of about 40. Unlabeled 12S RNA competes with the labeled species in hybridization experiments, whereas globin mRNA or mouse ascites 12S RNA does not. It is suggested that 12S RNA hybridizes only to
V
κ
-genes of the same subclass, and that there may be several hundred genes coding for
V
κ
-regions of all subclasses in a mouse genome. Moreover, gene amplification in myeloma cells is not detected.
Protein Initiation in Eukaryotes: Formation and Function of a Ternary Complex Composed of a Partially Purified Ribosomal Factor, Methionyl Transfer RNA
f
, and Guanosine Triphosphate
Authors: Levin Daniel H. , Kyner David , Acs George
Published: May 2006

A protein factor contained in a 1 M KCl extract of L-cell ribosomes and partially purified by chromatography on DEAE-cellulose forms a specific ternary complex with rat-liver Met-tRNA
f
and GTP. The complex is measured by its quantitative retention on nitrocellulose membranes. Complex assembly is optimal at 100 mM KCl and 0.2 mM MgCl
2
, and is independent of mRNA and of ribosomes. The GTP requirement can be replaced over 65% by its methylene analogue GDPCH
2
P, indicating that GTP hydrolysis is not involved. Complex formation is inhibited by 10 μM aurintricarboxylic acid, but is unaffected by 100 μM pactamycin, 100 μM fusidic acid, or by excess uncharged methionine tRNA
f
. The ternary complex is relatively stable and appears at the void volume during filtration on Sephadex G-100. At 1-3 mM MgCl
2
and in the presence of other factors, the ternary complex is implicated in protein initiation by (
i
) its capacity to bind to the 40S ribosomal subunit to form a 48S complex; and (
ii
) the subsequent association of the 48S complex with a 60S subunit to form a functional “80S complex.”
On the Theory of Ion Transport Across the Nerve Membrane, VII. Cooperativity Between Channels of a Large Square Lattice
Authors: Chen Yi-Der , Hill Terrell L.
Published: May 2006

The exact kinetics of a 10 × 10 Ising system (periodic boundary conditions) with two-state channels arranged in a square lattice was studied by computer simulation. With all three values of the cooperativity parameter used, no induction in the K
+
-current curve was obtained. This confirms one of our previous conclusions concerning K
+
channels in the squid axon membrane: models with interacting channels arranged in a twodimensional lattice (Adam's model) are apparently excluded. Other topics included: equilibrium properties; short-range pair correlation functions; phase transition.
Maternal Histone Messenger RNA: Detection by Molecular Hybridization
Authors: Skoultchi Arthur , Gross Paul R.
Published: May 2006

A competition-hybridization assay has been developed for the majority of sequences present in embryonically synthesized histone messenger RNA. The assay permits the first direct demonstration of specific “maternal” messengers in unfertilized sea-urchin eggs. The molecular size of histone messenger RNA stored in the egg appears to be the same as that of histone messenger RNA synthesized by the embryo. Maternal histone messenger RNA is found in the soluble phase of egg homogenates, in the form of ribonucleoprotein particles, unassociated with ribosomes.
Multiple Common Properties of Human β
2
-Microglobulin and the Common Portion Fragment Derived from HL-A Antigen Molecules
Authors: Nakamuro K. , Tanigaki N. , Pressman D.
Published: May 2006

11,000-Dalton common portion fragments derived from HL-A antigen molecules were isolated and found to have a significantly high homology to β
2
-microglobulin in amino-acid composition. Common portion fragments are also very similar to β
2
-microglobulin with respect to molecular size, charge, and distribution in tissues. Moreover, both are found in the spent culture media of human cell lines and in human plasma and urine. Thus it appears that β
2
-microglobulin may well be the same substance as the common portion fragment of HL-A antigen molecules.
A Theory of the Epigenesis of Neuronal Networks by Selective Stabilization of Synapses
Authors: Changeux Jean-Pierre , Courrége Philippe , Danchin Antoine
Published: May 2006

A formalism is introduced to represent the connective organization of an evolving neuronal network and the effects of environment on this organization by stabilization or degeneration of labile synapses associated with functioning. Learning, or the acquisition of an associative property, is related to a characteristic variability of the connective organization: the interaction of the environment with the genetic program is printed as a particular pattern of such organization through neuronal functioning. An application of the theory to the development of the neuromuscular junction is proposed and the basic selective aspect of learning emphasized.
Surface Antigens Common to Mouse Cleavage Embryos and Primitive Teratocarcinoma Cells in Culture
Authors: Artzt Karen , Dubois Philippe , Bennett Dorothea , Condamine Hubert , Babinet Charles , Jacob François
Published: May 2006

Syngeneic antisera have been produced in mouse strain 129/Sv-CP males against the primitive cells of teratocarcinoma. These sera react specifically with the primitive cells and are negative on various types of differentiated teratoma cells derived from the same original tumor. They are negative on all other mouse cells tested, with the exception of male germ cells and cleavage-stage embryos. Thus, teratoma cells possess cell-surface antigens in common with normal cleavage-stage embryos.
Integration of Deoxyribonucleic Acid Specific for Rous Sarcoma Virus after Infection of Permissive and Nonpermissive Hosts
Authors: Varmus Harold E. , Vogt Peter K. , Bishop J. Michael
Published: May 2006

A relatively simple but stringent technique was developed to detect the integration of virus-specific DNA into the genomes of higher organisms. In both permissive (duck) and nonpermissive (mammalian) cells which normally contain no nucleotide sequences specific for Rous sarcoma virus, transformation by the virus results in the appearance of DNA specific for Rous sarcoma virus covalently integrated into strands of host-cell DNA containing reiterated sequences. Early after infection of mouse or duck cells by Rous sarcoma virus, unintegrated DNA specific for the virus can be demonstrated.
Studies on
In Vitro
DNA Synthesis Isolation of
dna
B Gene Product from
Escherichia coli
Authors: Wright Michel , Wickner Sue , Hurwitz Jerard
Published: May 2006

Formation of duplex DNA from ϕX174 single-stranded DNA by extracts of
E. coli
was previously shown to require the gene product of
dna
B. Using as an assay the stimulation of ϕX174 DNA-dependent synthesis in inactivated extracts of
dna
B temperature-sensitive cells, we purified the
dna
B gene product from wild-type
E. coli
as well as from a
dna
B temperature-sensitive mutant. The
dna
B temperature-sensitive gene product is more thermolabile than its wild-type counterpart.
Three-Dimensional Structure of the Fab′ Fragment of a Human Immunoglobulin at 2.8-Å Resolution
Authors: Poljak R. J. , Amzel L. M. , Avey H. P. , Chen B. L. , Phizackerley R. P. , Saul F.
Published: May 2006

The structure of the Fab′ fragment of a human myeloma immunoglobulin was determined by x-ray crystallographic analysis at 2.8-Å resolution. The Fourier map of the electron density was correlated with the aminoacid sequence to obtain a three-dimensional model. Four globular subunits, which correspond to the homology regions of the light and heavy chains, are arranged in a tetrahedral configuration. These subunits closely resemble each other, sharing a basic pattern of polypeptide chain folding. In each subunit, long sequences of tightly packed, hydrogen bonded polypeptide chain run parallel to the major axis of the subunit. No helical conformation can be seen. Different patterns of interchain disulfide linkage and unusual intrachain disulfide bonds that have been observed in other immunoglobulins can be explained with this model. The regions of hypervariable sequences in the light and heavy chains occur at one end of the molecule, in close spatial proximity.
Regulation of Hemoglobin β-Chain Synthesis in Bone Marrow Erythroid Cells by α Chains
Authors: Wolf Jeffrey L. , Mason R. George , Honig George R.
Published: May 2006

Synthesis of α and β chains of hemoglobin was studied
in vitro
in intact reticulocytes and bone marrow cells. The cells were from rabbits having a variant form of hemoglobin in which L-isoleucine is in the α but not in the β chains. This characteristic permitted a selective inhibition of α-chain synthesis to be produced by addition to the incubation medium of L-
O
-methylthreonine, an inhibitor of protein synthesis that is a specific antagonist of L-isoleucine.

In studies with reticulocytes, 25 mM L-
O
-methylthreonine produced a 60-70% inhibition of α-chain synthesis, but β-chain synthesis was unaffected even after incubation times for 4 hr. Because reticulocytes contain a pool of uncombined α chains which might have obscured the demonstration of an α chain-dependent mechanism for β-chain synthesis, subsequent studies were done with bone marrow cells. The latter had little or no detectable α-chain pool. A substantial inhibition of α-chain synthesis by the bone marrow cells was produced by the isoleucine antagonist but was also accompanied by a significantly decreased rate of β-chain synthesis.

These findings suggest that the coordinated synthesis of the complementary α- and β-globin chains of hemoglobin may reflect in part a modifying effect of α-chain synthesis on the synthesis of β chains.
Bone Morphogenesis in Implants of Insoluble Bone Gelatin
Authors: Urist Marshall R. , Iwata Hisashi , Ceccotti Peter L. , Dorfman Robert L. , Boyd Stuart D. , McDowell Richard M. , Chien Constance
Published: May 2006

Insoluble bone gelatin with inclusions of insoluble noncollagenous protein produces new bone when implanted in muscle in allogeneic rats. The implanted residue provides the milieu for expression of bone morphogenetic potential of migratory mesenchymal cells. Neutral buffer solutions activate endogenous enzymes that degrade components essential for cell interactions and differentiation of bone. Chloroform-methanol either denatures or extracts constituents responsible for degradation. Insoluble bone gelatin produces new bone after extraction at 2° with neutral salts, 0.5 M EDTA, 0.1 M Tris·HCl, 4 M urea, 0.5 M hydroxylamine, and 10 M KCNS, as well as after limited digestion with pepsin or collagenase, but not after extraction with 5 M guanidine, 7 M urea, water saturated with phenol, or after alkali hydrolysis with 0.1 N NaOH. The specific activity of cell populations interacting with insoluble bone gelatin suggests that a chemical bond between collagen and a noncollagenous protein or part of a protein, cleaved by a neutral proteinase, controls the bone morphogenetic reaction.
Nonrepetitive DNA Sequence Representation in Sea Urchin Embryo Messenger RNA
Authors: Goldberg Robert B. , Galau Glenn A. , Britten Roy J. , Davidson Eric H.
Published: May 2006

Messenger RNA was prepared from developing sea urchin gastrulae by puromycin release from polyribosomes. Approximately 60% of the total mRNA radioactivity of the postnuclear supernatant was recovered and shown to be free of any other labeled RNA species such as ribosomal and nuclear RNA. The mRNA was examined by hybridization to DNA present in great excess. The mRNA hybridizes almost exclusively with nonrepetitive DNA. Almost all of the messenger RNA molecules of sea urchin gastrulae therefore consist of transcripts from nonrepetitive sequences. It appears that the structural genes expressed at this stage are typically not repeated in the genome and the mRNA does not include recognizable repetitive sequence.
Cytochrome
c
. Observation of Numerous Single-Carbon Sites of the Reduced and Oxidized Species by Means of Natural-Abundance
13
C Nuclear Magnetic Resonance Spectroscopy
Authors: Oldfield Eric , Allerhand Adam
Published: May 2006

Proton-decoupled, natural-abundance
13
C nuclear magnetic resonance spectra (obtained at 15.18 MHz by the Fourier transform method) of aqueous ferrocytochrome
c
, ferricytochrome
c
, and mixtures of both species were recorded. The 18 nonprotonated aromatic carbons of amino-acid residues and the 16 nonprotonated aromatic carbons of the heme yielded 22 narrow single-carbon resonances and 6 narrow two-carbon resonances in the spectrum of ferrocytochrome
c
. Only some of these resonances were detected in the spectrum of ferricytochrome
c
.

Fast electron transfer between ferrocytochrome
c
and ferricytochrome
c
produced chemical exchange effects in spectra of mixtures of the two species: 16 nonprotonated aromatic carbons yielded narrow exchange-averaged resonances as a consequence of their small natural linewidths in both redox states and the small changes in their chemical shifts (relative to the reciprocal of the lifetime between electron exchange) when going from the reduced to the oxidized species. These peaks were assigned to carbons situated far from the iron atom. Their fast exchange behavior was used to establish a one-to-one correspondence between resonances in spectra of the two redox states. The other 18 nonprotonated aromatic carbons yielded exchange-broadened resonances as a consequence of large chemical-shift differences between the diamagnetic and paramagnetic species, and/or large paramagnetic broadening of the resonances of ferricytochrome
c
. We assigned these resonances (only one of which was identified in the spectrum of ferricytochrome
c
alone) to carbons that are near the iron atom: C
ζ
of Tyr 67, C
γ
of His 18, and the 16 nonprotonated carbons of the porphyrin ring. Tentative specific assignments for C
ζ
of Tyr 67 (in the spectra of both redox forms) and for C
ζ
of His 18 (in the spectrum of ferrocytochrome
c
) are also presented.
Marker Discrimination in Transformation and Mutation of Pneumococcus
Authors: Tiraby J.-G. , Fox M. S.
Published: May 2006

Earlier investigations of pneumococcal transformation revealed a function (hex
+
) responsible for severely reducing the transformation yield of certain markers. A mutational alteration (hex
-
) responsible for the loss of this function has been transferred into a hex
+
strain to permit a comparison of the hex
+
and hex
-
phenotypes in an isogenic background.

The loss of the hex
+
function results both in a loss of the capacity to eliminate the low efficiency markers in transformation and a substantial increase in the spontaneous mutation rate. These properties of the hex
-
strain could result from the loss of a capacity to eliminate certain classes of mismatched base pairs that occur as intermediates in both transformation and mutagenesis.
The Amino-Acid Sequence of
lac
Repressor
Authors: Beyreuther Konrad , Adler Klaus , Geisler Norbert , Klemm Alex
Published: May 2006

The amino-acid sequence of
lac
repressor from
Escherichia coli
has been determined. The sequence contains 347 residues in the subunit single peptide chain. It shows no similarities with the sequences of histones or the known part of β-galactosidase.
Inhibitory Action of Ruthenium Red on Neuromuscular Transmission
Authors: Rahamimoff R. , Alnaes E.
Published: May 2006

The effect of Ruthenium Red on synaptic transmission was examined at isolated junctions of the frog, by conventional methods for stimulation and intracellular recording. Ruthenium Red (2.5-10.0 μM) reduces the synaptic potential to subthreshold levels. An analysis of this phenomenon shows that the main action of Ruthenium Red is on the presynaptic nerve terminal where it decreases the number of quanta of transmitter liberated by the nerve impulse. It has the following additional effects: a reduction in the amplitude of the spontaneous miniature end plate potentials; an increase in their frequency; and an increase in delayed release of transmitter after a nerve impulse. Some of these results are discussed in terms of the known inhibitory action of Ruthenium Red on calcium transport across mitochondrial membranes.
Molecular Nature of Mammalian Cell DNA in Alkaline Sucrose Gradients
Authors: Simpson Joseph R. , Nagle William A. , Bick Michael D. , Belli James A.
Published: May 2006

Mammalian cell DNA that exhibited anomalous sedimentation in alkaline sucrose gradients was examined directly by electron microscopy. Its appearance was that of duplex DNA. In addition, some duplex DNA was observed under conditions in which the sedimentation anomaly was no longer apparent. Persistence of double-stranded DNA under denaturing conditions suggests caution in the interpretation of changes in the molecular weight or conformation of DNA based solely on analysis of sedimentation profiles.
Purification of a Family of Specific Messenger Ribonucleic Acids from Moth Follicular Cells
Authors: Gelinas Richard E. , Kafatos Fotis C.
Published: May 2006

When moth follicular cells synthesize the characteristic, low-molecular-weight chorion (eggshell) proteins, they contain at least two groups of 8-9S RNAs which appear to be chorion mRNA. This class of RNA yields a characteristic radiolabeled profile on polyacrylamide slab gels. The same profile is obtained irrespective of whether lebeling is performed
in vivo
or in organ culture, and whether the RNAs are purified from whole cells or specifically released from polysomes. Polysomes contain putative chorion mRNA only when the cells actually synthesize chorion protein. The RNA size is correlated with the size of the chorion proteins: two month species differing in the size distribution of their chorion proteins show a corresponding difference in the size distribution of the RNAs.
Enzymatic Activities of Carboxypeptidase A's in Solution and in Crystals
Authors: Lipscomb William N.
Published: May 2006

Activities of all known forms of bovine carboxypeptidase A's (α having 307, β having 305, and γ having 300 amino acids) are essentially the same in solution under given conditions. However, activities in the crystals differ. The A
α
crystals elongated along the
a
axis (
a
) have unit cell parameters
a
= 51.41 Å,
b
= 59.89 Å,
c
= 47.19 Å, and β = 97°35′, (
b
) show about [unk] of the activity of the dissolved enzyme, and (
c
) have the same color of the arsanilazo Tyr 248 derivative in the crystalline and solution states, namely red at pH 8.2 and yellow at pH 7.4. The A
γ
crystals elongated along the
b
axis (
a
) have unit cell parameters
a
= 50.9 Å,
b
= 57.9 Å,
c
= 45.0 Å, and β = 94°40′, (
b
) show [unk] of the activity of the dissolved enzyme, and (
c
) show, in the arsanilazo Tyr 248 derivative, yellow crystals and red solution at pH 8.2.

Although the detailed three-dimensional structure is known for the A
α
form described above, the structure of the A
γ
form is as yet undertermined. A reasonable hypothesis is that the major part of the differences in crystal behaviors is due to differences in intermolecular (crystal-packing) interactions. In particular the movement of Tyr 248 may be somewhat hindered by these intermolecular contacts in the A
γ
crystals, and in other crystalline forms which are elongated along the
b
axis. The movement observed in the x-ray diffraction studies, of the OH group of Tyr 248 by 12 Å when the very slowly hydrolyzed substrate Gly-Tyr is bound to A
α
crystals, appears to be largely unhindered by intermolecular interactions.

Examination of a three-dimensional space-filling structural model of the carboxypeptidase A molecule reveals that the phenolic oxygen of Tyr 248 can approach within 2 Å of the Zn cofactor. This approach requires a movement by about 6 Å of the polypeptide chain in the general region of Tyr 248. Moreover, the position of Tyr 248 when bonded to Zn can just be seen in the electron density map of the crystal structure at a level which, averaged over many unit cells, suggests some 15-25% of the enzyme is in this form at pH 7.4 and 4° in the crystals of the x-ray diffraction study. It is probable that when the Zn-Tyr 248 bond is present the enzyme is catalytically inactive.
Isolation of
cis
-Zeatin from
Corynebacterium fascians
Cultures
Authors: Scarbrough Emanuel , Armstrong Donald J. , Skoog Folke , Frihart Charles R. , Leonard Nelson J.
Published: May 2006

Three cytokinin-active constituents have been isolated from the culture medium of
Corynebacterium fascians
, a plant pathogen causing fasciation. One constituent is now identified as
cis
-zeatin [6-(4-hydroxy-3-methyl-
cis
-2-butenylamino)purine]. It represents the first unequivocal demonstration of the production of a zeatin isomer by a bacterial species. Another constituent was identified earlier as 6-(3-methyl-2-butenyl-amino)purine. The third constituent, distinct, on Sephadex LH-20 column chromatography, from the above two and their ribosides, has not yet been identified.
Effect of the Removal of the Y Base on the Conformation of Yeast tRNA
Phe
Authors: Kearns David R. , Wong K. Lim , Wong Yeng P.
Published: May 2006

The effect of removing the Y base from the anticodon loop of yeast tRNA
Phe
has been examined by high-resolution proton nuclear magnetic resonance spectroscopy and optical melting. Analysis of the changes in the nuclear magnetic resonance spectra indicate that the removal of the Y base produces a small conformational change in the anticodon stem in which all the interbase separations are increased by approximately 0.2 Å. The temperature dependence of the nuclear magnetic resonance spectra and the optical melting measurements indicate that the high temperature stability of tRNA
Phe
is decreased by removal of the Y base. With the exception of the anticodon stem, the secondary structure of the other helical stems of the molecule appear to be unaltered when the Y base is excised.
The Ultrastructure of Ferritin Macromolecules. The Lattice Structure of the Core Crystallites
Authors: Massover William H. , Cowley John M.
Published: May 2006

The ultrastructure of the crystalline ferric mineral that forms the central core of ferritin macro-molecules has been examined by means of ultrahigh resolution electron microscopy at 100 kV. Very high magnification dark-field images reveal the presence of either a single large crystal or several smaller crystallites within many of the cores. When the highly crystalline core contents are suitably oriented to transmit their Bragg reflections through the objective aperture, regular fringes separated by 2-9.5 Å have been visualized. The geometrical relations of lattice fringes and of periodically organized point details in these individual crystallites largely confirm the structural model proposed by Towe and Bradley (1967). The highly variable occupancy of ferric ions in certain planes of the lattice suggests that 20-33% of the iron content of fully saturated ferritin should undergo more rapid physiological release than does the remainder, and that iron uptake will have kinetics that depend upon more than only the maximal rate of crystallization.