bluuebunny/crossref_metadata_2025 huggingface dataset:
MECHANISM OF DNA CHAIN GROWTH, IV. DIRECTION OF SYNTHESIS OF T4 SHORT DNA CHAINS AS REVEALED BY EXONUCLEOLYTIC DEGRADATION
Authors: Okazaki Tuneko , Okazaki Reiji
Published: May 2006

T4 nascent short chains labeled at their growing ends with H
3
-thymidine and uniformly with C
14
-thymidine were prepared, separated into complementary strands, and degraded by
E. coli
exonuclease I in the 3′ to 5′ direction or by
B. subtilis
nuclease in the 5′ to 3′ direction. The kinetics of release of H
3
and C
14
labels by both enzymes was consistent with the conclusion that the H
3
label is at the 3′ end of the nascent short chains of both strands and that the short chains are products of discontinuous synthesis in the 5′ to 3′ direction along the two template strands.
PROPERTIES OF HALVES OF IMMUNOGLOBULIN LIGHT CHAINS
Authors: Karlsson F. Anders , Peterson Per A. , Berggård Ingemar
Published: May 2006

Light polypeptide chains from both normal human γG immunoglobulin and Bence-Jones proteins can be cleaved into halves by limited proteolysis with trypsin, pepsin, or papain. The fragments were obtained in yields of up to 22 per cent, had molecular weights of 10,000 to 11,000, and were shown by amino acid analysis and antigenic analysis to correspond to variable or constant regions of light chains. Starch gel electrophoresis in urea suggested that each half consisted of a single polypeptide chain. A fragment from the urine of a myeloma patient corresponded almost exactly to the constant half of a γ-chain and had a compact shape (Stokes radius of 16 Å; frictional ratio of 1.1). Similar Stokes radii were estimated both on fragments from normal urine and fragments produced by proteolysis of normal light chains.

The results are consistent with the view that most urinary fragments have a catabolic origin and suggest that there is a small stretch of polypeptide chain between the compact V and C regions of light chains which is particularly susceptible to proteolysis. This lends support to the hypothesis that immunoglobulin chains consist of globular domains connected by more extended stretches of polypeptide chain.
TRANSIENT CHANGES IN EXTRINSIC FLUORESCENCE OF NERVE PRODUCED BY ELECTRIC STIMULATION
Authors: Tasaki I. , Carnay L. , Watanabe A.
Published: May 2006

Nerves stained with one of the following fluorochromes were found to respond to electric stimulation with transient changes in the fluorescent light: acridine orange, acridine yellow, 8-anilinonaphthalene-1-sulfonate, auramine O, 1-dimethylaminonaphthalene-5-sulfonyl chloride, fluorescein isothiocyanate, LSD, pyronin B, pyronin Y, rhodamine B, rhodamine G, rose bengal, and 2-toluidinylnaphthalene sulfonate. The properties of covalently bonded fluorochromes in the nerve and the behavior of fluorochromes introduced into the axon interior were studied. By measuring fluorescence polarization, direct evidence was obtained showing a decrease in intramembrane viscosity during the action potential.
Sympathetic Nerve Cell Destruction in Newborn Mammals by 6-Hydroxydopamine
Authors: Angeletti P. U. , Levi-Montalcini R.
Published: May 2006

A selective and permanent destruction of sympathetic ganglia was achieved by injecting 6-hydroxydopamine in newborn animals. A lifelong chemical sympathectomy may thus be obtained. The process of cell damage and destruction is substantially different from that produced with an antiserum to a specific nerve growth factor.
In vitro
Malignant Transformation by Methylcholanthrene of the Progeny of Single Cells Derived from C3H Mouse Prostate
Authors: Mondal Sukdeb , Heidelberger Charles
Published: May 2006

Cell lines derived from C3H mouse ventral prostate grow to a monolayer, do not pile up, and do not give tumors on inoculation into isologous mice. When treated with carcinogenic hydrocarbons, these cells produce piledup colonies that give rise to fibrosarcomas in mice; these colonies are termed transformed. Individual single cells were treated with 0.5 per cent dimethyl sulfoxide (DMSO), and 2 per cent of them gave rise to clones containing transformed colonies. Under optimal conditions, treatment of individual single cells with 3-methylcholanthrene (MCA) led to the formation of transformed colonies in 100 per cent of the clones. From recloning experiments, it appears probable that all the progeny of the MCA-treated cells were potentially transformed, although the time required for the transformation to be scored was variable. It is concluded that in this system the carcinogen does not select for pre-existing malignant cells.
Carbon-13 Nuclear Magnetic Resonance: Naturally Occurring Nucleosides
Authors: Jones Alan J. , Winkley Michael W. , Grant David M. , Robins Roland K.
Published: May 2006

The natural-abundance carbon-13 nuclear magnetic resonance spectra of the naturally occuring pyrimidine and purine nucleosides have been determined and completely analyzed. The carbon-13 chemical shifts obtained provide information on the electronic structure and qualitatively at least correlate well with the known chemical reactivity of these molecules. The carbon-13 shifts are in general far more informative than proton shifts for structural analysis of the nucleosides.
Kinetics of Heterogeneous Chemical Reactions, II
Authors: Lin S. H. , Eyring H.
Published: May 2006

The first-order and zero-order kinetics of heterogeneous reactions coupled with the diffusion process are studied. The differential equations of these reaction systems are solved for the cases in which the fluid is not stirred and the fluid is well stirred. It is shown that both the rate constants and the diffusion coefficient can be determined in various ways depending on the experimental conditions.
Report on the Teichmüller Metric
Authors: Royden H. L.
Published: May 2006

Let

T
g

be the Teichmüller space of compact Riemann surfaces of genus
g
. Then

T
g

is the space of conformal structures on a fixed surface
W
modulo equivalence under conformal maps homotopic to the identity. The Teichmüller modular group [unk] is the group of all orientation preserving homeomorphisms of
W
onto itself modulo those which are homotopic to the identity. Each element of [unk] induces a biholomorphic map of

T
g

onto itself, and the present note outlines a proof of the converse statement: Every biholomorphic map of

T
g

onto itself is induced by an element of [unk]. It is first shown that every isometry of

T
g

with the Teichmüller metric arises from an element of [unk]. The Teichmüller metric is then shown to be the Kobayashi metric for

T
g

and hence invariant under biholomorphic maps.
Nerve Growth Factor from Cobra Venom
Authors: Angeletti R. Hogue
Published: May 2006

The chemical and biological properties of the nerve growth factor isolated from
Naja naja
venom are described. The nerve growth promoting activity appears to be distinct from the most commonly known enzymes and toxins present in the venom. The purified nerve growth factor from cobra venom has properties remarkably similar to those of the nerve growth factor isolated from mouse submaxillary gland. These findings are discussed in connection with the problem of the physiological function of this unique protein in the two species.
The Role of Phosphatidylglycerol in the Vectorial Phosphorylation of Sugar by Isolated Bacterial Membrane Preparations
Authors: Milner L. S. , Kaback H. R.
Published: May 2006

Phospholipase D (cabbage) inhibits the vectorial phosphorylation of α-methylglucoside by isolated membrane preparations from
Escherichia coli
ML 308-225 without increasing the efflux of intramembranal α-methylglucoside-P. This effect is shown to be related to the ability of phospholipase D to hydrolyze membrane phosphatidylglycerol specifically. After treatment with phospholipase D, the membranes resynthesize phosphatidylglycerol with a return in their ability to take up α-methylglucoside. Since proline uptake by the same preparations is only slightly inhibited by phospholipase D, the data indicate that phosphatidylglycerol is required specifically for transport processes which are mediated by the P-enolpyruvate-P-transferase system.
Models of Structure of the Envelope of Influenza Virus
Authors: Tiffany John M. , Blough Herbert A.
Published: May 2006

Possible models of the structure of the influenza virus envelope are considered in terms of the known chemical composition. Models incorporating lipid in the form of a bimolecular leaflet are shown to be unlikely on geometrical grounds. A model having „inverted toadstool” protein units separated by spherical lipid micelles is favored, and is capable of explaining the appearance of the virus in the electron microscope and differences between normal and incomplete (von Magnus) forms of the virus.
Helix Probability Profiles of Denatured Proteins and Their Correlation with Native Structures
Authors: Lewis P. N. , G[unk]o N. , G[unk]o M. , Kotelchuck D. , Scheraga H. A.
Published: May 2006

The Zimm-Bragg formulation for the one-dimensional Ising model is applied to denatured proteins in order to compute helix probability profiles with different σ and
s
parameters for the various amino acids; the latter are in principle determinable from melting curves for helix-coil transitions in random copolymers of amino acids. Using a tentative assignment of σ and
s
values, we found a correlation for the propensity of a residue to be helical in the denatured protein and its occurrence in a helical region in the globular structure of the corresponding native protein. Thus, these incipient helical regions in the denatured chain may serve to nucleate the folding to form the native protein. Short-range interactions appear to determine the tendency for a residue to be helical or not, whereas long-range interactions may serve to carry out the nucleation and refolding processes.
Stimulation of Mammalian Erythropoiesis by 5β-H Steroid Metabolites
Authors: Gordon Albert S. , Zanjani Esmail D. , Levere Richard D. , Kappas Attallah
Published: May 2006

The effects of a number of steroid compounds on erythropoiesis in normal and polycythemic mice were examined. Of the steroids that stimulated erythropoiesis, the hormone testosterone and certain 5β-H C
19
and C
21
nonhormonal metabolites were the most effective. Anti-erythropoietin abolished the erythropoiesis-stimulating effects of testosterone but not those exerted by the 5β-H steroid, 11-ketopregnanolone. Similarly, testosterone but not 11-ketopregnanolone evoked the production of erythropoiesis-stimulating factor in rats. It is concluded that two mechanisms underlie the stimulating actions of steroids on erythropoiesis; one through the production of erythropoietin and the second involving a more direct influence on the blood-forming tissues. The 5β-H steroid metabolites are postulated to act on erythropoiesis via the latter mechanism.
Relative Effect of Transcription-Level and Translation-Level Control of Protein Synthesis during Early Development of the Sea Urchin
Authors: Terman Stanley A.
Published: May 2006

Newly synthesized proteins were pulse labeled with radioactive amino acids at several developmental stages of the sea urchin,
Arbacia punctulata
—in normal embryos and in embryos continuously exposed to the drug Dactinomycin. The soluble proteins were fractionated by electrophoresis through polyacrylamide gels. A simple procedure for complete solubilization of the proteins in slices of gels into a solution of toluene for liquid scintillation counting, and a computer program to display and to compare statistically the distributions of
14
C- and
3
H-labeled proteins fractionated on the same gel, allowed quantitative statements to be made on the relative changes in protein synthesis. The conclusion is that translation-level control provides most of the changes in protein synthesis that occur between fertilization and hatched blastula stage.
DNA Complementary to Viral RNA in Leukemic Cells Induced by Avian Myeloblastosis Virus
Authors: Baluda M. A. , Nayak D. P.
Published: May 2006

Nucleic acid hybridization studies were made between 71S-AMV-RNA and DNA from leukemic myeloblasts and from normal chicken cells. There was homology between the viral RNA and chicken cell DNA and to a greater extent between viral RNA and leukemic cell DNA. Leukemic cell DNA hybridized approximately twice as much viral RNA as did normal chicken DNA. Thermal melting studies showed that the viral RNA bound to normal and leukemic cell DNA consists of long polynucleotides (

T
m

= 87° and 92°C, respectively, in 2× saline citrate). This suggests that the leukemic cells contain a DNA template of the viral RNA.
Evidence for Control of Synthesis of the Variable Regions of the Heavy Chains of Immunoglobulins G and M by the Same Gene
Authors: Wang A. C. , Wilson S. K. , Hopper J. E. , Fudenberg H. H. , Nisonoff A.
Published: May 2006

Previous work indicated that the light chains of a monotypic immunoglobulins G2-K and M-K from a single patient (Ti1) are identical. Our present data show that the monotypic immunoglobulins G and M share idiotypic determinants not present in their isolated light chains or in any of a large number of other immunoglobulins tested, and that amino acid sequences of the first 27 residues from the NH
2
-terminal end of the γ- and μ-chains are identical. These results support the hypothesis that at least two genes control the synthesis of each heavy and light chain and suggest that the monotypic immunoglobulin G and monotypic immunoglobulin M of this patient share three of the four genes involved. It is proposed that, during normal immunoglobulin synthesis, different cells of a single clone synthesize immunoglobulins M and G, and that the light chains and the variable segments of the heavy chains of the proteins of the two classes are identical within the clone. A genetic switching mechanism is suggested.
Leukemia Viruses Associated with Mouse Myeloma Cells
Authors: Watson J. , Ralph P. , Sarkar S. , Cohn Melvin
Published: May 2006

Myeloma cells derived from BALB/c and C3H mice show evidence of infection by a murine leumemia virus. The immunoglobulin-producing myelomas secrete an RNA-containing virus with a density of 1.20 to 1.22 gm/cm
3
. RNA with a sedimentation coefficient of 74 S in 0.1
M
sodium sodium chloride has been isolated from secreted virus particles and has a base composition similar to that found for other murine leukemia virus RNA. An intracellular virus particle has been partially purified and has a density of 1.29 to 1.32 gm/cm
3
. Both extracellular and intracellular virus particles contain the leukemia virus group-specific antigen.
Synthesis of Acid Mucopolysaccharides by Glial Tumor Cells in Tissue Culture
Authors: Dorfman Albert , Ho Pei-Lee
Published: May 2006

A clonal strain of rat glial tumor cells was shown to produce the acid mucopolysaccharides, hyaluronic acid, chondroitin 4-SO
4
, and heparan sulfate in tissue culture. The mucopolysaccharides were isolated both from the growth medium and the cells.
Studies of the Mechanism of Anthranilate Synthase Reaction
Authors: Tamir H. , Srinivasan P. R.
Published: May 2006

The enzyme anthranilate synthase catalyzes the formation of anthranilate form either chorismate and glutamine or chorismate and ammonia. In the aromatization of chorismate, a hydroxyl group and an enolpyruvyl group must be eliminated. Elimination of the enolpyruvyl group of chorismate is accompanied by protonation to form pyruvate. The source of this proton was investigated by performing the enzymatic reaction in 99.7 per cent D
2
O.

The isolated pyruvate contained close to an atom of deuterium in the methyl group. High resolution mass spectra also revealed that about 6 per cent of the deuterio pyruvate contains a -CHD
2
species. Thus, the results obtained conclusively demonstrate that in the formation of the pyruvate, the third hydrogen of the methyl group arises from water and not by intramolecular shift of a hydrogen from the ring of chorismate.
Binding of Dodecyl Sulfate to Proteins at High Binding Ratios. Possible Implications for the State of Proteins in Biological Membranes
Authors: Reynolds Jacqueline A. , Tanford Charles
Published: May 2006

A wide variety of proteins have been shown to bind identical amounts of an amphiphile, sodium dodecyl sulfate, on a gram per gram basis at monomer equilibrium concentrations above 0.5 mM. The binding is independent of ionic strength and primarily hydrophobic in nature. Only the monomeric form of the amphiphile binds to proteins, not the micellar form. The application of these results to models for biological membranes and to gel electrophoresis in sodium dodecyl sulfate is discussed.
Effect of Sodium Ions on Calcium Movements in Isolated Synaptic Terminals
Authors: Blaustein M. P. , Wiesmann W. P.
Published: May 2006

Calcium accumulation has been studied in isolated presynaptic nerve terminals from rat brain. Calcium influx is increased when external sodium is replaced by lithium or choline, or when the internal sodium concentration is increased by treatment with ouabain. Calcium efflux is reduced when external sodium is replaced by lithium. The lithium-stimulated calcium accumulation appears to be associated with the nerve terminals, and not with mitochondria or membrane fragments. It is dependent upon an osmotically sensitive surface membrane. The results are consistent with the hypothesis that calcium is actively extruded from mammalian central neurons by a mechanism which exchanges calcium for sodium, and which derives its energy from the sodium concentration gradient.
Specific Separation of Cells on Affinity Columns
Authors: Truffa-Bachi Paolo , Wofsy Leon
Published: May 2006

Cell filtration is performed on affinity columns prepared by the chemical modification of large polyacrylamide beads. Affinity columns selectively bind cells that produce antihapten antibodies of corresponding specificity, while cells without the specific antihapten sites pass through freely and are recovered quantitatively in the eluate. The binding of the antihapten specific cells is inhibited by hapten. Such cell filtration affinity columns may be useful in specifically purifying cell populations with characteristic membrane-receptor proteins.
Catabolite-Insensitive Revertants of
Lac
Promoter Mutants
Authors: Silverstone Allen E. , Arditti R. Rita , Magasanik Boris
Published: May 2006

The maximum rate of expression of the
lac
operon is severely reduced in
lac
promoter mutants. Revertants of these mutations which produce higher levels of enzyme were isolated. Some of these revertants had lost sensitivity to catabolite repression and transient repression. The mutations responsible for these losses took place at sites very close to the original promoter mutations. From these results we conclude that the promoter itself is the target site for both catabolite and transient repression of the
lac
operon.
Conformational Similarity of Ovine Prolactin and Bovine Growth Hormone
Authors: Aloj S. M. , Edelhoch H.
Published: May 2006

The behavior and properties of ovine prolactin have been evaluated by measurements of fluorescence, polarization of fluorescence, absorption, optical rotation, and circular dichroism. The helical content of the native molecule at pH 8 is 60 per cent as determined by circular dichroism. Three molecular transitions have been followed. The one in acid affects only 20 per cent of the helical residues. More profound conformational changes occur in urea solutions (pH 5.2 and 8.0) where most of the helical residues are randomized. There is a close parallel between the behavior of ovine prolactin and bovine growth hormone both in aqueous solutions between pH 2 and 11.5 and in urea solutions at pH 5.2 and 8.0. Based on the similarities in behavior it is proposed that the conformations of these two hormones are homologous.
Cytochalasin B: Effects upon Microfilaments Involved in Morphogenesis of Estrogen-Induced Glands of Oviduct
Authors: Wrenn Joan T. , Wessells Norman K.
Published: May 2006

The administration of estrogen to immature chicks induces formation of tubular glands and differentiation of cells in the oviduct. As glands begin to form, organized bundles of 40-50 Å filaments appear at the luminal end of the cells. These structures are not present in uninduced oviducts. Cytochalasin treatment of oviducts early in gland formation results in the disappearance of young glands already present and the inhibition of new gland formation. Furthermore, organized microfilaments are no longer present. When the oviducts are washed free of cytochalasin, however, organized bundles of microfilaments reappear.

The correlations between the presence of filaments and formation and glands suggest that filaments are important agents in morphogenesis, presumably because of contractile properties which generate changes in cell shape and, consequently, tissue shape.
SUBUNIT HETEROGENEITY IN HUMAN SERUM BETA LIPOPROTEIN
Authors: Kane J. P. , Richards E. G. , Havel R. J.
Published: May 2006

The apoprotein of human serum beta lipoprotein has been prepared in a lipid-free and soluble form by a technique of interfacial extraction in the presence of guanidinium hydrochloride and nonionic amphiphile. Gel permeation chromatography of maleylated apobeta lipoprotein separates two protein fractions with different amino acid compositions. The smaller particle has a molecular weight of 2.6 × 10
4
.
IRON: ITS INTRACELLULAR LOCALIZATION AND POSSIBLE ROLE IN CELL DIVISION
Authors: Robbins Elliott , Pederson Thoru
Published: May 2006

When HeLa cells are fixed with ethanol, extracted with 0.1 N HCl, and incinerated at 540°C, all organic constituents and all ions studied are removed with the exception of iron. The gross outlines of cell structures are preserved and high concentrations of residual ash in interphase nucleoli and mitotic chromosomes suggest that there may be a shift in iron salts during the cell cycle. Experiments with cells isotopically labeled in proteins, nucleic acids, lipids, and polysaccharides indicate that the iron is bound to a polysaccharide. Addition of iron chelating agents to living cells causes a selective inhibition of DNA synthesis. These data suggest that iron may play a crucial role in the mitotic process.
PROMITOCHONDRIA OF ANAEROBICALLY GROWN YEAST, IV. CONVERSION INTO RESPIRING MITOCHONDRIA
Authors: Plattner H. , Salpeter M. M. , Saltzgaber J. , Schatz G.
Published: May 2006

Promitochondria of anaerobically grown
Saccharomyces cerevisiae
were selectively labeled
in vivo
by incubating the cells with [
3
H]leucine and cycloheximide. When the labeled cells were washed free of cycloheximide and adapted to oxygen in the presence of unlabeled leucine, the respiring mitochondria formed during adaptation proved to be radioactive. In contrast, only insignificant label was found in iso-1-cytochrome
c
which is synthesized
de novo
during adaptation. Respiratory adaptation of anaerobically grown yeast thus involves differentiation of promitochondrial organelles.
The Septate Junction: A Structural Basis for Intercellular Coupling
Authors: Gilula Norton B. , Branton Daniel , Satir Peter
Published: May 2006

Electron microscopy, freeze-etching, and optical diffraction show how the structure of the septate junction may provide the basis for the low-resistance pathway between the electrically coupled cells in mussel gill epithelia. Conventional electron microscopy suggests that the septa are pleated sheets that differentiate from and are structurally continuous with the junctional cell membranes. Freeze-etching exposes geometrically arranged rows of 85-Å particles within the junctional cell membranes. Diffraction evidence shows that these membrane particles and the alternate vertices of the intercellular septal sheets are congruent and therefore superposable. Together, the membrane particles and septal sheets provide a channel that extends from the cytoplasm of one cell through the septate junction to the cytoplasm of the adjacent cell.
ATP-Dependent and Cyclic AMP-Dependent Activation of Rat Adipose Tissue Lipase by Protein Kinase from Rabbit Skeletal Muscle
Authors: Huttunen Jussi K. , Steinberg Daniel , Mayer Steven E.
Published: May 2006

Brief incubation of partially purified preparations of hormone-sensitive lipase from rat epididymal fat pads with ATP, Mg
++
, cyclic adenosine 3′:5′-monophosphate and rabbit muscle protein kinase (phosphorylase
b
kinase kinase) resulted in enhancement of lipolytic activity (44-93%). Little or no activation was observed when either the cofactor mixture or the protein kinase was omitted. When the fat pads were incubated with epinephrine prior to homogenization, addition of kinase and cofactors to the soluble supernatant fraction caused no activation whereas good activation was obtained in preparations from paired fat pads not exposed to epinephrine. The results indicate that the cyclic AMP-mediated activation of hormone-sensitive lipase in adipose tissue involves a protein phosphorylation step. Whether the lipase itself is phosphorylated and thus activated or whether the protein kinase is activating a mediating enzyme, in analogy with its action in the glycogen phosphorylase system, remains to be determined.
On Existence Theorems for Nonlinear Equations Involving Noncompact Mappings
Authors: Petryshyn W. V.
Published: May 2006

In this note we present two new theorems concerning the solvability of nonlinear equations in normed linear spaces involving either
K
-coercive pseudo-
A
-proper mappings (Theorem 1) or their uniform limits (Theorem 2). These theorems are then used to obtain certain known as well as new existence results for various special classes of equations involving, for example,
A
-proper and
P
-compact operators;
K
-monotone, quasi-
K
-monotone and pseudo-
K
-monotone operators; monotone and others.
Group-Specific Antigen Expression During Embryogenesis of the Genome of the C-Type RNA Tumor Virus: Implications for Ontogenesis and Oncogenesis
Authors: Huebner Robert J. , Kelloff Gary J. , Sarma Padman S. , Lane William T. , Turner Horace C. , Gilden Raymond V. , Oroszlan Stephen , Meier Hans , Myers David D. , Peters Robert L.
Published: May 2006

Tests for the group-specific antigen of the C-type RNA tumor virus showed that mouse embryos of all strains tested, at some stage of development
in utero
, revealed detectable titers of group-specific antigen in one or more of their tissues; younger, rather than older, embryos were likely to be positive, particularly in those strains which normally reveal little or no expression of the RNA genome postnatally. The antigens were found in embryos of low-leukemia strains, free of infectious virus. These new findings support a previously stated hypothesis that the genome of RNA tumor viruses, mostly switched off for infectious virus expression, is vertically transmitted as part of the natural genetic apparatus of normal mouse cells. Since group-specific antigens have also been described in chick embryos and immunological tolerance to homologous group-specific antigens has been demonstrated in hamsters and cats as well as in mice and chickens, the hypothesis has been extended to include vertebrate cells in general. Finally, the high incidence and titers of the group-specific antigen suggest that the genes for RNA tumor virus, which later in life act as determinants of cancer, may be important also as gene determinants in the developing embryo.
DNA and Gene Therapy: Uncoating of Polyoma Pseudovirus in Mouse Embryo Cells
Authors: Osterman Joseph V. , Waddell Anna , Aposhian H. Vasken
Published: May 2006

Pseudovirions (host DNA fragments encapsidated by polyoma virus-coat protein) and polyoma virions are produced after infection of primary mouse embryo cells with polyoma virus. Purified pseudovirions are adsorbed to, and uncoated by, mouse embryo cells. The evidence for this uncoating is based on the conversion by pancreatic DNase of the uncoated pseudovirus DNA from an acid-insoluble to an acid-soluble form. The implications of these experiments to the eventual use of DNA for gene therapy are discussed.
On the Fundamental Group of Manifolds of Non-positive Curvature
Authors: Yau Shing Tung
Published: May 2006

We prove theorems on the structure of the fundamental group of a compact riemannian manifold of non-positive curvature. In particular, a conjecture of J. Wolf [
J. Differential Geometry
, 2, 421-446 (1968)] is proved.
The Selective Inhibition of Protein Initiation by T4 Phage-Induced Factors
Authors: Klem Edward B. , Hsu Wen-Tah , Weiss Samuel B.
Published: May 2006

The phenomenon of selective translation of T4 template RNA by ribosomes from T4-infected cells, or factors derived therefrom, has been extended to studies on the initiation of protein synthesis. A high-salt extract derived from T4-infected ribosomes inhibits the formation of initiation complexes of MS2 and
Escherichia coli
template RNA with uninfected ribosomes while efficiently supporting the formation of initiation complexes with T4 template RNA. T4 factors also permit T5 template RNA to bind to
E. coli
ribosomes, which indicates that the T4 selective effect is not exclusive for T4 templates. Other evidence indicates that T4 factors do not alter the process of polypeptide chain elongation.
Loss Due to Missing Data in Efficiency of a Locally Optimal Test for Homogeneity with Respect to Very Rare Events
Authors: Puri Prem S.
Published: May 2006

With reference to observations of supernovae in galaxies, a locally optimal test for the hypothesis of homogeneity of the observational units with respect to occurrence of supernovae (treated as a very rare event) is obtained for the case where the data are available only for those galaxies where at least one supernova is observed. It is shown that the loss in the asymptotic efficiency of the test due to lack of reporting of galaxies with no supernovae is very heavy and in fact is infinite for the case of very rare events.
On the Process of Cellular Division in
Escherichia coli
, V. Incorporation of Deoxynucleoside Triphosphates by DNA Thermosensitive Mutants of
Escherichia coli
Also Lacking DNA Polymerase Activity
Authors: Mordoh José , Hirota Yukinori , Jacob François
Published: May 2006

Double mutants of
Escherichia coli
were constructed by combining DNA thermosensitive mutations affecting either DNA initiation (DnaA) or elongation (DnaB) with the Pol A1 mutation, which abolishes DNA polymerase activity. Incorporation of labeled deoxynucleoside triphosphates was studied in these mutants using toluene-treated cells. This incorporation was found to be exactly correlated with the capacity of the mutants to synthesize DNA
in vivo
.
Regulation of Acetylcholinesterase in Neuroblastoma Cells
Authors: Blume A. , Gilbert F. , Wilson S. , Farber J. , Rosenberg R. , Nirenberg M.
Published: May 2006

The specific activity of mouse neuroblastoma acetylcholinesterase (EC 3.1.1.7) increased 25-fold when the rate of cell division was restricted. The results show that acetylcholinesterase activity is regulated in neuroblastoma cells and that the regulatory mechanism is inversely related to the rate of cell division. Under the same conditions the specific activity of catechol-
O
-methyl transferase (EC 2.1.1.6) did not change significantly.
Kinetic Model of Conduction Changes across Excitable Membranes
Authors: Jain Mahendra K. , Marks Richard H. L. , Cordes E. H.
Published: May 2006

A kinetic model describing conduction changes across excitable membranes is proposed. It assumes that a population of discrete membrane sites is distributed among several distinct functional states determined by the voltage across the membrane. Interconversion of these states is postulated to occur by first-order reactions. It provides a satisfactory description of the central aspects of excitable membrane behavior, including current-time and current-voltage relationships, action potential, and effects of inhibitors.
Correlation of Adrenocorticotropic Activity of ACTH Analogs with Degree of Binding to an Adrenal Cortical Particulate Preparation
Authors: Hofmann Klaus , Wingender Winfried , Finn Frances M.
Published: May 2006

This study deals with the interaction of polypeptide hormones with their receptors. Specifically it involves the binding of synthetic ACTH analogs and fragments to a particulate fraction from beef adrenal cortical tissue. This fraction was found to bind synthetic [
14
C-Phe] [Gln
5
]β-corticotropin
1-20
amide but failed to bind significant amounts of [
14
C-Phe] [Gln
5
]β-corticotropin
1-10
. The former peptide exhibits a high degree
in vivo
adrenocorticotropic activity in the rat; the latter is inactive. [
14
C-Phe] [Gln
5
]β-corticotropin
1-20
amide exhibited little affinity for similarly prepared particulates from beef kidney, liver, or adrenal medulla. Using a series of synthetic homogeneous nonradioactive analogs or fragments of β-corticotropin
1-20
amide to displace [
14
C-Phe] [Gln
5
]β-corticotropin
1-20
amide from the particulate fraction a significant correlation between binding and
in vivo
adrenocorticotropic activity was established. Major „active” and „binding” sites were shown to reside in different sections of the ACTH molecule. Charged groups play a major role in the attachment of ACTH to the particulate fraction and the sequence Lys-Lys-Arg-Arg proved to be particularly significant. The high degree of binding specificity for ACTH peptides which is exhibited by the particulate suggests that it contains ACTH receptor(s). Moreover, the striking similarity between observations with the S-peptide-S-protein model system and the system described would seem to indicate that the ACTH receptor is a protein.
Release of Pituitary Growth Hormone by Prostaglandins and Dibutyryl Adenosine Cyclic 3′:5′-Monophosphate in the Absence of Protein Synthesis
Authors: MacLeod Robert M. , Lehmeyer Joyee E.
Published: May 2006

Effects of prostaglandins on the incorporation of [4,5-
3
H]leucine into growth hormone and its subsequent release into the incubation medium were studied. Incubation of rat anterior pituitary glands with 10
-6
M prostaglandin PGE
1
in tissue culture medium 199 for 7 hr caused a 40-300% increase in the release of labeled growth hormone into the incubation medium. PGE
1
at 10
-8
M increased growth hormone synthesis but not release. At 10
-6
M, PGE
2
had effects similar to PGE
1
; PGA
1
increased growth hormone synthesis but not release. PGF
2α
was without effect on either synthesis or release of growth hormone.

Prolactin synthesis and release were not affected by prostaglandins. All of the prostaglandins, at 10
-4
M, increased adenyl cyclase activity in the pituitary gland but phosphodiesterase activity was unaltered. Dibutyryl cyclic AMP, with or without caffeine, caused an up to 300% increase in labeled growth hormone release. No consistent effect of prolactin was observed. If potassium concentration was increased 10-fold, a 215% increase in growth hormone release was observed. A combination of hypertonic potassium and 10
-6
M PGE
1
increased growth hormone release 325%, suggesting that potassium and prostaglandins act by independent mechanisms. Addition of theophylline to pituitary gland, incubated
in vitro
, increased both the synthesis and release of growth hormone. Although fluoride greatly stimulated growth hormone release, it completely inhibited the incorporation of leucine into the hormone. Similarly, puromycin inhibited synthesis of growth hormone but did not block release induced by prostaglandin, dibutyryl cyclic AMP, theophylline, or fluoride. Prostaglandins increase pituitary adenyl cyclase activity and, presumably via cyclic AMP, increase growth hormone release, independently of protein synthesis.
Cellular Aspects of the Inverse Relationship between the Net Charge of Immunogens and of Antibodies Elicited
Authors: Sela Michael , Mozes Edna , Shearer G. M. , Karniely Yuval
Published: May 2006

The results reported establish a cellular basis for the inverse relationship between the net electrical charge of immunogens and of the antibodies provoked by them. Glass bead columns were used to reduce the number of immunocompetent spleen cells preferentially reactive with more acidic immunogens. After a single immunization, titers of antibodies to an acidic dinitrophenylated copolymer of tyrosine, glutamic acid, and lysine (DNP-901) elicited in recipient mice by filtered spleen cells were significantly lower than those generated by unfiltered cells. After secondary stimulation, the major portion of the antibodies provoked by the acidic antigen was found in the more acidic fraction eluted from DEAE-Sephadex, in contrast to the more basic antibodies, of the same specificity, generated by unfiltered spleen cells. Results obtained by transplanting a limiting number of spleen cells indicate a depletion in the number of precursor cells reactive with dinitrophenyl on DNP-901 after glass bead chromatography, whereas there was no change in the response to dinitrophenyl on a basic copolymer, DNP-912, containing the same amino acids in different molar ratios.
On Finitely Additive Vector Measures
Authors: Brooks James K. , Jewett Robert S.
Published: May 2006

In this paper we extend the well-known Vitali-Hahn-Saks and Nikodým theorems for measures to finitely additive vector-valued set functions.
Altered Nucleic Acids of Antibody-Forming Tissues
Authors: Little J. Russell , Donahue Helaine A.
Published: May 2006

RNA·DNA hybridization experiments suggest differences between the DNA from the liver and spleen of the same animal (rabbit) and between the RNAs from lymph nodes stimulated by different antigens. A larger proportion of spleen DNA than of liver DNA was complementary to the RNA isolated from antigen-stimulated lymph nodes. No difference between liver and spleen DNA was observed in hybrids formed with RNA from lymph nodes of nonimmune animals. This suggests the presence of unique or redundant genes coding for immunoglobulin polypeptide chains in antibody-forming cells.
6-(
p
-Hydroxyphenylazo)-uracil: A Selective Inhibitor of Host DNA Replication in Phage-Infected
Bacillus subtilis
Authors: Brown Neal C.
Published: May 2006

The azopyrimidine, 6-(
p
-hydroxyphenylazo)-uracil, inhibits the replication of bacterial DNA selectively, completely, and reversibly, and has no apparent effects on the metabolism of other cellular macromolecules thus far examined. The mechanism of its action has been investigated in uninfected and phage-infected
Bacillus subtilis
, and the compound appears to be specific for a host function. In cells infected with virulent phage the synthesis of phage DNA proceeds normally, while residual host DNA synthesis is completely blocked. The drug-sensitive host site retains its sensitivity even after partial disruption of the cell by lysozyme treatment.
A Short Stereoselective Synthesis of Cecropia Juvenile Hormone. Experimental Details
Authors: Loew Peter , Siddall John B. , Spain Virginia L. , Werthemann Lucius
Published: May 2006

Experimental details are reported for a previously described synthesis of cecropia juvenile hormone.
Ribosomal Proteins, XIII. Molecular Weights of Isolated Ribosomal Proteins of
Escherichia coli
Authors: Dzionara M. , Kaltschmidt E. , Wittmann H. G.
Published: May 2006

Molecular weights of the isolated proteins from the 30S and 50S ribosomal subunits of
Escherichia coli
were determined by two independent methods: polyacrylamide gel electrophoresis with sodium dodecylsulphate and equilibrium sedimentation. The values for the molecular weights determined by gel electrophoresis range from 10,900 to 65,000 for the proteins of the 30S subunit and from 9,600 to 31,500 for those of the 50S subunit, with number averages of 19,000 and 16,300, respectively, in agreement with those obtained by equilibrium sedimentation.
Identical Linear Order of Chromosomes in Both Gametes of the Acoel Turbellarian
Polychoerus carmelensis:
A Preliminary Note
Authors: Costello Donald P.
Published: May 2006

In an exceptionally well-defined first cleavage metaphase in a sectioned egg of
Polychoerus carmelensis
all 34 (2n) chromosomes were present in a single 8-micron section, and it was possible to identify the homologous chromosomes derived from the two parent gametes. Three groups of chromosomes from one parent, containing 7, 7, and 3 chromosomes, respectively, could be exactly matched by corresponding groups of homologues derived from the other gamete. The probability of such an ordered pattern occurring by chance is somewhat less than 1 in 2
48
. The simplest explanation of this arrangement is that the 17 chromosomes contributed by the egg were in precisely the same linear order as those contributed by the spermatozoon. This suggests that during certain stages preceding first cleavage metaphase, the 17 members of each haploid set of chromosomes may have been attached, end-to-end, in a linear fashion, by highly specific bonds.
Specificity of the DNA Product of the C-Type Virus RNA-Dependent DNA Polymerase
Authors: Hatanaka Masakazu , Huebner Robert J. , Gilden Raymond V.
Published: May 2006

The specificity of the DNA product of the RNA-dependent DNA polymerase found in C-type virions was analyzed by reciprocal hybridization with RNA from viruses of mouse, hamster, cat, and viper. These tests revealed a clear species specificity for the DNA product with no detectable interspecies hybridization.
Theory of the Voltage Clamp of the Nerve Membrane, I. Ideal Clamp
Authors: Nó R. Lorente De
Published: May 2006

The mathematical theory of the flow of current during a voltage clamp has been developed for a nerve membrane having constant conductance and for a membrane whose conductance increases during activity. It is found that the published families of voltage clamp records are compatible only with a practically constant membrane conductance.
Stability of Plane Poiseuille Flow to Periodic Disturbances of Finite Amplitude, II
Authors: Pekeris C. L. , Shkoller B.
Published: May 2006

The stability of plane Poiseuille flow to periodic disturbances of finite amplitude was investigated by expanding each harmonic of the solution in terms of the Orr-Sommerfeld eigenfunctions with coefficients which are functions of time. The system of nonlinear ordinary differential equations for the coefficients was solved, and the number of harmonics
N
was extended from 3, of the previous investigation, to 5. The shift in the neutral curve in going from
N
= 3 to
N
= 5 is considerable, indicating insufficient convergence. The higher-order harmonics are effective because the zone of mode-coalescence rises with increasing
N
.
Energy Transfer in Modified DNA
Authors: Pochon F. , Kapuler A. M. , Michelson A. M.
Published: May 2006

Energy transfer at room temperature and in aqueous solution between two hydrocarbon chromophores, 2-acetylaminofluorene and 7-methylbenz(a)anthracene, covalently attached to DNA and to homopolynucleotide models is described. Transfer, as evidenced by changes in fluorescence intensity and polarization, is a function of secondary structure.
Studies on Memory: Distribution of Peptidyl-Puromycin in Subcellular Fractions of Mouse Brain
Authors: Flexner L. B. , Gambetti P. , Flexner J. B. , Roberts R. B.
Published: May 2006

Previous experience has led us to suggest that sustained blockage of memory in mice upon administration of puromycin is caused by the persistence of peptidyl-puromycin at synapses. The block can be removed and memory restored by intracerebral injections of water and by subcutaneous or intraperitoneal injections of several psychotropic drugs. The present experiments provide evidence that peptidyl-puromycin persists for long periods in subcellular fractions of synaptosomes (nerve endings), and that the peptide is lost from synaptosomal, but not from mitochondrial, fractions when memory is restored. These findings strengthen our interpretation of the mode of action of puromycin on memory.
Fatty Acid Synthetase Activity in
Mycobacterium phlei:
Regulation by Polysaccharides
Authors: Ilton M. , Jevans A. W. , McCarthy E. D. , Vance D. , White H. B. , Bloch Konrad
Published: May 2006

The multienzyme complex from
Mycobacterium phlei
which catalyzes the synthesis of long chain fatty acids from acetyl-CoA and malonyl-CoA requires a heat-stable fraction (stimulating factor, SF) for activity. Fractionation of heat-treated
M. phlei
extracts affords two stimulatory subfractions, one of which (SF
2
) can be replaced by FMN. The other (SF
1
) is further separable into 3 polysaccharides (PS
I
, PS
II
, and PS
III
). PS
I
contains about 95% 3-
O
-methylmannose and 5% mannose; the sugar composition of PS
II
and PS
III
is about 55% 6-
O
-methylglucose and 45% glucose for both. Each of the three purified polysaccharides, in combination with FMN, substitutes for the crude stimulating factor. The polysaccharides exert their effect on the fatty acid synthetase by lowering the

K
m

for acetyl-CoA about 50-fold.
RNA Polymerases of Maize: Partial Purification and Properties of the Chloroplast Enzyme
Authors: Bottomley Warwick , Smith Harriet Jane , Bogorad Lawrence
Published: May 2006

A DNA-dependent RNA polymerase has been solubilized and partially purified from washed chloroplasts prepared from maize seedlings. The purified enzyme was completely dependent on added DNA after purification by phospho- or DEAE-cellulose chromatography. On glycerol density gradients, the enzyme ran ahead of a marker with a sedimentation constant of 18 S, indicating a molecular weight of 500,000 or more. The instability of the highly purified enzyme made intensive study difficult, but the properties of the enzyme purified by phosphocellulose chromatography are reported. Template specificity varied during purification but the activity was always higher with denatured than with native DNA and the preference for maize DNA over calf-thymus DNA increased during purification. The enzyme required magnesium for optimal activity, was inhibited by salt concentrations in excess of 0.1 M, and had a temperature optimum of 48°C. The chloroplast enzyme differed from similar activities so far reported from maize or other sources, particularly in the high salt concentrations needed to elute it from phosphocellulose. The soluble, DNA-dependent enzyme was not inhibited by either α-amanitin or by rifamycin-SV under the assay conditions used.
Inactivation of Ribosomes
In Vitro
by Colicin E
3
Authors: Boon Thierry
Published: May 2006

Cell-free protein synthesizing extracts incubated with purified preparations of colicin E
3
showed a marked decrease of their protein synthesizing activity. Incubation of ribosomes prepared from S-30 extracts with E
3
resulted in their inactivation. Their 16S RNA was found to lose a terminal fragment, similar in size to the fragment released upon
in vivo
treatment with E
3
. Extracts derived from colicinogenic strains are resistant to the action of E
3
in vitro
.
Control of Single Ribosome Formation by an Initiation Factor for Protein Synthesis
Authors: Kaempfer Raymond
Published: May 2006

30 and 50S ribosomal subunits, released from polysomes upon polypeptide chain termination, possess a high affinity for each other and readily form single ribosomes. Highly purified initiation factor F3(B), acting stoichiometrically, prevents the formation of single ribosomes without promoting their dissociation. These findings are interpreted in terms of a ribosome cycle in which a limiting amount of factor F3(B) controls the number of ribosomes active in protein synthesis, in response to metabolic changes in the cell, by regulating the flow of ribosomal subunits into polysomes or into a sidetrack pool of synthetically inactive single ribosomes. The reported apparent ribosome dissociation activity of F3(B) is explained.