bluuebunny/crossref_metadata_2025 huggingface dataset:
Induction of Translocations in Mature Drosophila Oocytes Over a Dose Range of 10-500 Roentgens of X-Rays
Authors: Abrahamson S. , Gullifor P. , Sabol E. , Voigtlander J.
Published: May 2006

Data are presented that demonstrate that a dose of 10 R of x-rays to mature oocytes in Drosophila causes a significant increase, more than double the spontaneous frequency, of inherited translocations. The dose-frequency relationship appears to fit best a linear response between 10 and 50 R. From 50 to 500 R, the frequency of rearrangements increases at the conventional dose 3/2 relationship.
Molecular Characteristics of Some Carcinogenic Hydrocarbons
Authors: Cavalieri Ercole , Calvin Melvin
Published: May 2006

The chemical reactivity and presumably the carcinogenic activity induced in aromatic hydrocarbons by hydroxylating enzymes may be due to the generation of electrophilic centers in some (benzo[a]pyrene) or nucleophilic centers in others (7,12-dimethylbenz[a]anthracene or 3-methylcholanthrene). These centers, which are at positions complementary to the points of activation by acid-derived protons (models of the positive oxygen of the hydroxylating enzymes), may react simultaneously with corresponding cellular components.
Quantitative Two-Dimensional Ultrastructural Distribution of Rh
o
(D) Antigenic Sites on Human Erythrocyte Membranes
*
Authors: Nicolson Garth L. , Masouredis S. P. , Singer S. J.
Published: May 2006

A method is described for determining the two-dimensional distribution of specific antigens on cell surfaces, and is applied to the D antigen of the Rh antigenic system. Rh-positive human erythrocytes are allowed to react with purified
125
I-labeled human anti-Rh
o
(D) γ-globulin antibodies, and the sensitized cells are then lysed at an air-water interface. The residual cell membranes are spread flat by surface forces, and are picked up on a carbon-strengthened collodion-coated electron microscope grid. The membranes are then stained with ferritin-conjugated goat antibodies directed against human γ-globulins. Only Rh-positive cells sensitized with anti-Rh
o
(D) antibodies bind the ferritin-conjugated antihuman γ-globulins. The ferritin particles are found in small clusters on the membrane surface, and the number of such clusters per unit area agrees with the number of
125
I-labeled anti-Rh
o
(D) antibodies bound per unit area. The Rh
o
(D) antigenic sites appear to be molecularly dispersed on the membrane surface, but in a random two dimensional array.
Prolonged Survival of Glutaraldehyde-Treated Skin Homografts
Authors: Schechter Israel
Published: May 2006

Treatment of mouse skin homografts
in vitro
with glutaraldehyde prolonged their average survival time from 12.4 to 39.2 days, presumably because the reagent became covalently bound to the histocompatibility antigen sites (or in their close vicinity) and shielded them from the immune apparatus of the recipient. The attachment to skin of the inert polymer poly(
L
-lysine) via this bifunctional reagent increased the average survival time to 52.9 days. The simplicity and versatility of this approach might make it possible to screen a large number of reagents that can bind covalently to tissue constituents under physiological conditions. It seems possible that a particular treatment leading to a new contact surface in the transplant might favor the acceptance of homografts as well as of heterografts.
In Vitro
Desensitization of Sensitized Murine Lymphocytes by a Serum Factor (Soluble Antigen?)
Authors: Brawn R. J.
Published: May 2006

The possibility that lymphocytes sensitized to cell-associated antigens may be rendered hyporeactive toward cells expressing these antigens by prior incubation with such antigens in soluble form was investigated. Mice were sensitized to the foreign histocompatibility antigens of an allogeneic strain of mice; lymphocytes from such sensitized mice were incubated with serum from normal mice of the sensitizing, sensitized, and F
1
hybrids of the two strains. These lymphocytes were washed and their
in vitro
activity against preparations of cells of sensitizing strain origin was measured by modifications of a standard assay. Sera from the sensitizing strain, and from F
1
hybrids of the sensitizing and sensitized strains (which would be expected to contain the soluble histocompatibility antigens to which the lymphocytes were sensitized), abrogated the
in vitro
activity of lymphocytes against target cells of the sensitizing strain, while serum from the sensitized strain did not. Soluble tumor-specific or histocompatibility antigens may be responsible in part for the specific abrogation of sensitized lymphocyte activity by serum from tumorbearing, successfully allografted, allogeneically pregnant, or chimeric animals.
Stimulation of the Proliferation of Chicken Fibroblasts by Folic Acid or a Serum Factor(s) in a Plasma-Containing Medium
Authors: Balk Samuel D.
Published: May 2006

The proliferation of chicken fibroblasts is strongly stimulated by folic acid, at greater than physiological concentrations, in a plasma-containing medium, or by serum in a medium of physiological folic acid concentration. Serum and plasma, however, do not appear to differ in their content of folic acid derivatives.

A qualitative difference between the proliferative behaviors of normal and transformed fibroblasts is obtained when these cells are cultivated in a physiological-folate-low-calcium-plasma medium. In such a medium, transformants proliferate steadily, at a significant rate, while normal fibroblasts do not multiply at all.
Initial Dipeptide Formation in Hemoglobin Biosynthesis
Authors: Crystal R. G. , Shafritz D. A. , Prichard P. M. , Anderson W. F.
Published: May 2006

Initiation factors M
1
+ M
2
from reticulocyte ribosomes bind Met-tRNA
F
to rabbit reticulocyte ribosomes containing endogenous hemoglobin mRNA. The initial binding of Met-tRNA
F
appears to be to the small ribosomal subunit. The Met-tRNA
F
is able to participate in what is presumed to be the first peptide bond in the formation of hemoglobin, namely the synthesis of a methionyl-valine dipeptide. The formation of this methionyl-valine dipeptide requires Met-tRNA
F
, initiation factors M
1
, M
2
, and M
3
, as well as Val-tRNA and T
1
. No synthesis of methionyl-valine dipeptide takes place if Met-tRNA
F
is replaced by Met-tRNA
M
, or if initiation factor M
3
is omitted. Thus, Met-tRNA
F
appears to be the initiator tRNA for hemoglobin biosynthesis and M
3
, although required for the synthesis of the first peptide bond of hemoglobin, does not appear to be necessary, under the experimental conditions studied, for Met-tRNA
F
binding.
Kinetics of Sodium Dodecyl Sulfate Solubilization of
Mycoplasma laidlawii
Plasma Membranes
Authors: Auborn James J. , Eyring Edward M. , Choules G. Lew
Published: May 2006

The kinetics of sodium dodecyl sulfate solubilization of aqueous suspensions of
Mycoplasma laidlawii
membranes have been investigated by light scattering in a stopped-flow apparatus. There was evidence of direct interaction between the membranes and sodium dodecyl sulfate micelles above the critical micelle concentration, although of lower order kinetically than with monomeric dodecyl sulfate anions below the critical micelle concentration. The activation energy remained the same in either case, about 10 kcal/mol. Static light-scattering studies at higher resolution showed that the solubilized membranes are in the form of small aggregates.
Serum-Stimulated Release of Cell Contacts and the Initiation of Growth in Contact-Inhibited Chick Fibroblasts
Authors: Baker Joffre B. , Humphreys Tom
Published: May 2006

Increased serum concentration in the medium of a confluent culture increases the overlapping of cells and the average rate of cell movement. The relationship between these two serum activities and serum release of growth inhibition was studied. The increase in overlaps does not appear to be directly related to release of growth since it occurs well after growth has been initiated. The increased rate of cell movement occurred immediately after the addition of serum and was quantitatively proportional to the stimulation of DNA synthesis over a range of serum concentrations, implying that both movement and growth are released by a common serum activity. Direct microscopic observation and time-lapse films reveal a reduction in cell contacts concurrent with the increase in cell movement. Experiments showed that cell movement at low cell densities, where cell contacts are minimal, was rapid in low serum concentration and was not stimulated by increasing the serum concentration. This suggests that the serum effect on cell movement involves cell contacts and is due to release of cell contacts in the confluent monolayer. The primary action of serum may be the disruption of adhesive cell contacts.
Ramsey's Theorem for a Class of Categories
Authors: Graham R. L. , Leeb K. , Rothschild B. L.
Published: May 2006

Ramsey's Theorem states that for a sufficiently large set
S
, and for any splitting of the
k
-element subsets of
S
into
r
classes, there is a subset
T
[unk]
S
, [unk]
T
[unk] =
l
, such that all
k
-element subsets of
T
are in the same class. This paper establishes a theorem for certain categories that generalizes Ramsey's Theorem. In particular, it is strong enough to establish G-C. Rota's conjecture that the vector space analogue to Ramsey's Theorem is true. It also implies the Ramsey theorem for
n
-parameter sets, which has as corollaries, among others, the theorem of van der Waerden on arithmetic progressions and several results of R. Rado on regularity in systems of linear equations.
Polyamine Stimulation of Nucleic Acid Synthesis in an Uninfected and Phage-Infected Polyamine Auxotroph of
Escherichia coli
K12
Authors: Dion Arnold S. , Cohen Seymour S.
Published: May 2006

The addition of arginine to cultures of
Escherichia coli
K12 deficient in agmatine ureohydrolase (EC 3.5.3.7) results in polyamine depletion and a striking inhibition of nucleic acid accumulation and growth. The omission of lysine from these cultures leads to a further decrease in growth rate and nucleic acid synthesis. In arginine-inhibited cells the addition of putrescine or spermidine, in the presence or absence of lysine, restores the control rate of growth and nucleic acid accumulation. Under the same conditions of arginine inhibition in the absence of lysine, the addition of cadeverine alone stimulates growth rate and RNA synthesis. The addition of lysine to polyamine-depleted cultures results in cadaverine production and in the appearance of a new spermidine analogue, containing lysine carbon. The new compound has been identified as
N
-3-aminopropyl-1,5-diaminopentane.

Infection of this arginine-inhibited, polyamine-depleted mutant with T
4
D results in markedly decreased amounts of DNA accumulation, as compared to infected cells uninhibited by arginine. Supplementation of arginine-inhibited infected cells by putrescine or spermidine restores DNA synthesis to the uninhibited level.
Defective Formation of the Lamellar Cytoplasm by Neoplastic Fibroblasts
Authors: Domnina L. V. , Ivanova O. Y. , Margolis L. B. , Olshevskaja L. V. , Rovensky Y. A. , Vasiliev J. M. , Gelfand I. M.
Published: May 2006

Isolated cultures of mouse L-cells are similar to those of normal cells in showing contact inhibition of movement and topoinhibition of growth. In mixed cultures with untransformed mouse embryo fibroblasts, their parent strain, however, L cells are able to form colonies above the monolayer of normal fibroblasts, i.e., they have a property characteristic of transformed cells. Analysis of microcinematographic data suggests that the behavior of L cells in mixed cultures is a result of their defective attachment to the substratum. Scanning electron microscopy showed that attachment of a normal fibroblast was accompanied by the formation of a wide ring of flattened cytoplasm spread on the substratum (lamellar cytoplasm). This structure was observed to disintegrate in newly attached L cells. The structure of the lamellar cytoplasm remained abnormal in the fully spread L cells. The mean area of lamellar cytoplasm was 3- to 4-times less in L cells than in normal fibroblasts.

It is suggested that deficient formation of lamellar cytoplasm may be the basis of the inability of L cells to interact normally with embryo fibroblasts.
Cytological Mapping of Human X-Linked Genes by Use of Somatic Cell Hybrids Involving an X-Autosome Translocation
Authors: Grzeschik K. H. , Allderdice P. W. , Grzeschik A. , Opitz J. M. , Miller O. J. , Siniscalco M.
Published: May 2006

Man-mouse and man-Syrian hamster somatic hybrid cell lines were prepared by fusion of mouse A9 or hamster TG2 cells, which are deficient in hypoxanthine-guanine phosphoribosyl transferase, with cells of a diploid fibroblastic strain, KOP-1, derived from a woman heterozygous for an X-autosome translocation. 61 clones were derived in nonselective medium and 85 sublines of these were derived in selective media: 53 in hypoxanthine-aminopterine-thymidine and 32 in 8-azaguanine. All three human X-linked markers studied, i.e., hypoxanthineguanine phosphoribosyl transferase (EC 2.4.2.8), glucose-6-phosphate dehydrogenase (EC 1.1.1.49), and phosphoglycerate kinase (EC 2.7.2.3), were present together, or absent together, in most of these clones and sublines. However, loss or retention of only phosphoglycerate kinase was occasionally observed, even in the absence of selective growth, while no evidence of separation of hypoxanthine-guanine phosphoribosyl transferase from glucose-6-phosphate dehydrogenase occurred. Cytological examination of eight man-hamster clonal lines by the quinacrine fluorescent technique showed that human phosphoglycerate kinase was only present when the translocation chromosome carrying most of the long arm of the X chromosome was present. The presence of human glucose-6-phosphate dehydrogenase and hypoxanthine-guanine phosphoribosyl transferase was not related to the presence or absence of this chromosome, but appeared to be correlated with the presence of the other translocation chromosome.
Activation of Epstein-Barr Virus by 5-Bromodeoxyuridine in “Virus-Free” Human Cells
Authors: Gerber Paul
Published: May 2006

Treatment of three human lymphoid cell lines, free of detectable Epstein-Barr virus, with 5-bromodeoxyuridine resulted in activation of virus synthesis in up to 8% of the cells. The induction of infectious virus could be demonstrated by cocultivation experiments with peripheral leukocytes. These studies demonstrated that the entire viral genome may persist in at least a portion of the lymphoid cells.
Identification of the Cardiac Beta-Adrenergic Receptor Protein: Solubilization and Purification by Affinity Chromatography
Authors: Lefkowitz Robert J. , Haber Edgar , O'Hara Donald
Published: May 2006

A protein that binds catecholamines with a specificity parallel to that of their
in vivo
effects on cardiac contractility (isoproterenol > epinephrine or norepinephrine > dopamine > dihydroxyphenylalanine) was solubilized from a microsomal fraction of canine ventricular myocardium. The binding protein was purified 500 to 800-fold by solubilization and subsequent affinity chromatography with conjugates of norepinephrine linked to agarose beads. Purified β-adrenergic binding protein exists in two forms, corresponding to molecular weights of 40,000 and 160,000. The purified material has a single association constant, 2.3 × 10
5
liters/mol (as compared to two association constants, 10
7
and 10
6
liters/mol, for the binding protein in particulate form) but retains the identical binding specificity for β-adrenergic drugs and antagonists.
Similarities Between the Conformation of Arsanilazotyrosine 248 of Carboxypeptidase A
α
in the Crystalline State and in Solution
Authors: Quiocho Florante A. , Mcmurray Cecil H. , Lipscomb William N.
Published: May 2006

Modification of carboxypeptidase A
γ
crystals (Anson) with diazotized arsanilic acid specifically labels tyrosine 248; at pH 8.2 the modified enzyme gives yellow crystals, but a red solution. It has been suggested that arsanilazotyrosine 248 forms a complex with the Zn cofactor accounting for the red color in solution, but that a complex is not formed in the crystal. However, the crystal structure of carboxypeptidase A
γ
is unknown. We show here that crystals of carboxypeptidase A
α
, whose crystal structure has been determined, are red both in solution and in the crystalline state (at pH 8.2) after modification with diazotized arsanilic acid. These new data are of importance in relating the structure in the crystalline state to the catalytic mechanisms, as based on the x-ray diffraction evidence.

The activity of carboxypeptidase A in the crystal and in solution has a ratio of only 1/3 for the α form, in contrast to the ratio of 1/300 for the γ form, with carbobenzoxyglycyl-L-phenylalanine as a substrate.

A pH-jump experiment monitored by stopped-flow kinetics in a split-beam apparatus has revealed a single exponential rate when a solution of arsanilazotyrosine 248 carboxypeptidase A
α
at pH 6.7 (yellow) is increased to pH 8.5 (red). The rate constants obtained in this experiment are 6.1 sec
-1
at 3.0 mg/ml and 7.2 sec
-1
at 1.6 mg/ml concentration of enzyme.
DNA-Dependent DNA Polymerases I and II from Normal Human-Blood Lymphocytes
Authors: Smith R. Graham , Gallo Robert C.
Published: May 2006

Two DNA polymerases have been purified from blood lymphocytes of normal human individuals. In contrast to a DNA polymerase isolated from lymphoblasts from individuals with leukemia, neither of the DNA polymerases from normal lymphocytes transcribes the heteropolymeric regions of tumor-virus RNA into DNA.
Existence of Phospholipid Bilayer Structure in the Inner Membrane of Mitochondria
Authors: Hsia J. C. , Chen W. L. , Long R. A. , Wong L. T. , Kalow W.
Published: May 2006

The presence of ordered phospholipid lamellar structure in inner membranes of mitochondria was detected with the use of a spin-labeled 2,4-dinitrophenol. A phospholipid bilayer may be an important structural and functional component of the inner mitochondrial membrane.
Fluidity: A General Theory
Authors: Hildebrand J. H. , Lamoreaux R. H.
Published: May 2006

The equation ϕ =
B
(
V
-
V
o
)/
V
o
, which reproduces the fluidity of simple liquids accurately over ranges between freezing and boiling points, is here shown to hold to pressures of at least 500 atm, and nearly to critical volumes. Fluidity can vary continuously above the critical region into that of compressed gas, where the parameter
B
becomes a function of temperature.

The parameter
V
o
is a “corresponding states” fraction of the critical molal volume. It is identical with the molal volume of the solid only in cases where molecules are free to rotate as they do in the liquid.

Parameter
B
is a measure of the extent to which the external momentum that produces viscous flow is absorbed by the molecules of the liquid. Such damping can result from molecular mass, e.g., Ne, Ar, Kr; flexibility, normal alkanes; or rotational inertia, SiBr
4
against SiCl
4
.
Tumorigenicity, Immunogenicity, and Virus Production in Mouse Melanoma Cells Treated with 5-Bromodeoxyuridine
Authors: Silagi Selma , Beju Delia , Wrathall Jean , Deharven Etienne
Published: May 2006

Bromodeoxyuridine (BrdU), whether administered in a 30-hr pulse of 30 μg/ml or continuously in low concentrations (1-3 μg/ml), significantly increased production of particles with the morphology of murine leukemia virus in a mouse melanoma (B16) cell line. Particles were very rare in control cells, detectable only by electron microscopy. By contrast, in many experiments with BrdU-treated cells the numbers of virus particles counted by electron microscopy increased over 100-fold, and other tests for murine leukemia virus (plaque assay and tests for group-specific antigens 1 and 3 and for Gross cell-surface antigens) became positive. All BrdU-treated cells, regardless of drug concentration or length of treatment, in addition to showing loss of both pigment and of piled-up morphology, were suppressed in tumorigenicity compared with the control cells. These effects were all reversible. A significant percentage of mice injected with BrdU-treated cells were protected against subsequent tumor formation when challenged with malignant control cells. The degree of protection conferred on the mice correlated well with the number of virus particles counted in the injected cells. There was also good correlation between the amount of cell-associated virus and the degree of suppression of malignancy for cells treated continuously with 1 μg of BrdU per ml, but not as good for cells treated for short periods with higher concentrations of BrdU.
Staphylococcal Protease: A Proteolytic Enzyme Specific for Glutamoyl Bonds
Authors: Houmard Jean , Drapeau Gabriel R.
Published: May 2006

An extracellular protease of
Staphylococcus aureus
, strain V8, previously shown to cleave specifically the peptide bonds on the carboxyl-terminal side of either aspartate or glutamate residues in phosphate buffer (pH 7.8) hydrolyzes only glutamoyl bonds in either ammonium bicarbonate (pH 7.8) or ammonium acetate (pH 4.0). Of all aspartoyl bonds tested, only the Asp-Gly linkage is cleaved at a detectable rate. The staphylococcal protease hydrolyzes all of the seventeen different glutamoyl bonds studied, although those involving hydrophobic aminoacid residues with bulky side chains are cleaved at a lower rate.
Structure and Function of
Escherichia coli
Formylmethionine Transfer RNA: Loss of Methionine Acceptor Activity by Modification of a Specific Guanosine Residue in the Acceptor Stem of Formylmethionine Transfer RNA from
Escherichia coli
Authors: Schulman Ladonne H.
Published: May 2006

The structural requirements of
E. coli
formylmethionine tRNA for aminoacylation have been examined by chemical modification of the tRNA, followed by separation of the modified molecules into active and inactive components. Photooxidation of tRNA
fMet
at 50° in the presence of methylene blue results in modification of two guanosine (G) residues in the acceptor stem, at positions no. 2 and no. 71 from the 5′-phosphate terminus. Both of these modifications are present in inactive molecules, but only the G residue at position no. 2 is modified in the acceptor stem of active molecules. Loss of methionine acceptance occurs with first-order kinetics, indicating that inactivation by modification of G residue no. 71 is independent of any other modifications taking place under these conditions. The presence of a modified G residue at position no. 2 in the acceptor stem of active photooxidized molecules shows that disruption of normal base-pairing in this region is not sufficient to inactivate tRNA
fMet
. These data indicate that the inactivating modification at position no. 71 is lethal due to a specific alteration in the nucleotide base, rather than simply as a result of breaking a hydrogen-bonded base pair in the acceptor stem.
Problems on Periodic Simple Continued Fractions
Authors: Chowla P. , Chowla S.
Published: May 2006

Let
N
be a positive non-square integer and

a
1
,a
2
,...,a
3

be the partial denominators in the period of length
s = s(N)
of the continued fraction for √
N
. Also let Σ

N
= a
3
- a
3-1
+ -... ± a
1

, and let
h(d)
be the class-number of
Q
(√
d
). Hirzebruch (unpublished) recently found the surprising theorem (which is a special case of more general results): If
p
is a prime≡3(4) and
p
> 3, then
h(p)
= 1 implies that Σ

p

= 3
h(-p)
.

This result led to related conjectures presented herein.
Transglutaminase from Hair Follicle of Guinea Pig
Authors: Chung S. I. , Folk J. E.
Published: May 2006

Two transglutaminases are found in homogenates of the inner root sheaths of guinea pig hair-follicles. One is indistinguishable from the well-characterized liver transglutaminase [
J. Biol. Chem.
, 246, 1093 (1971)]. The other, which is present in far greater quantity, has not been detected in other organs or tissues. Gel filtration and polyacrylamide gel electrophoresis studies indicate that the native hair-follicle enzyme, of molecular weight 54,000, is composed of two subunits of identical molecular weight. Specificity studies suggest that the intermolecular cross-linking of fibrin and fibrinogen that is catalyzed by this enzyme is a result of the formation of ε(γ-glutamyl)lysine bonds. The probable participation of hair-follicle transglutaminase in the formation of these cross-links in the proteins of hair is discussed.
Gene Dosage Dependence of Pigment Synthesis in Melanoma x Fibroblast Hybrids
Authors: Fougére Catherine , Ruiz Françoise , Ephrussi Boris
Published: May 2006

Hybrids between Syrian hamster melanoma cells and mouse fibroblasts, containing one genome (1
s
) of each parent, produce neither melanin nor DOPA-oxidase (“extinction”). Attempts to induce loss of the fibroblast chromosomes by irradiation of the fibroblasts before fusion with melanoma cells resulted in the formation of colonies comprising pigmented hybrid cells, which contained 2
s
melanoma and 1
s
fibroblast chromosome-complements suggesting that extinction or re-expression of melanogenesis is a function of genic balance. This interpretation was confirmed by crosses between 2
s
melanoma cells with unirradiated 1
s
fibroblasts, which produced both pigmented and unpigmented hybrids. No correlation has thus far been established between karyotype and phenotype of the hybrid cells, but analysis of the karyological data suggests that the fibroblast chromosomes responsible for extinction cannot be numerous.
Role of Transcription in the Temporal Control of Development in
Caulobacter crescentus
Authors: Newton Austin
Published: May 2006

The requirement for transcription during development of the stalked bacterium,
Caulobacter crescentus
, was studied with synchronous cultures of swarmer cells. The developmental pattern in these bacteria was first established by determination of the times at which specific changes in cell structure and function occurred. These changes could be divided into those characteristic of (
a
) development of the swarmer cell into the stalked cell: loss of motility and synthesis of the stalk, and (
b
) development of the stalked cell into the asymmetric dividing cell: chromosome replication, synthesis of the flagellum, motility, and division. The effect of rifampin in blocking several of these steps—loss of motility, initiation of chromosome replication, and cell division—indicates that RNA synthesis is required throughout the cell cycle for normal differentiation.
Cis
-Limited Action of the Gene-A Product of Bacteriophage ϕX174 and the Essential Bacterial Site
Authors: Francke Bertold , Ray Dan S.
Published: May 2006

Parental replicative-form (RF
*
) DNA of bacteriophage ϕX174 in a replication-deficient host cell (
rep
3
-
) exhibits two characteristic features that correlate the function of viral gene A with the initiation of viral DNA replication: a specific discontinuity in the viral strand of a constant number of RF molecules and elongation of the viral strand to yield replicative-intermediate DNA forms with single-stranded tails. At high multiplicities of infection, these initiation events are limited to an average of four specifically nicked RFII molecules per cell. The limiting factor from the host cell may be related (or identical) to the essential bacterial sites known to limit the participation of parental genomes in RF replication. Double-infection experiments with wild-type phage and phage carrying an amber mutation in gene A show that the formation of gene A-specific RFII and RI is
cis
-limited to only the wild-type DNA. These results provide a basis at the DNA level for the known asymmetric complementation of gene A.
Differentiation of Neuromuscular Junctions in Cultures of Embryonic
Drosophila
Cells
Authors: Seecof Robert L. , Teplitz Raymond L. , Gerson Inés , Ikeda Kazuo , Donady J. James
Published: May 2006

Cultures were prepared of embryonic cells from
Drosophila melanogaster
. Neurons and myocytes differentiated
in vitro
from their respective stem cells. Electron microscopy showed that neuromuscular junctions formed where axons contacted myocytes. Electrical stimuli were applied to axons and these caused contractions of innervated myocytes. This is the first report of insect or other invertebrate neuromuscular junctions differentiating
in vitro
. In addition, this is the first system reported in which the neurons, myocytes, and junctions are completely differentiated
in vitro
from neuroblasts and myoblasts.
Regeneration and Changes in Synaptic Connections between Individual Nerve Cells in the Central Nervous System of the Leech
Authors: Jansen J. K. S. , Nicholls J. G.
Published: May 2006

The central nervous system of the leech has been used for the study of the formation of new synaptic connections by regenerating neurons. In control leeches, individual nerve cells in adjacent ganglia are connected in an orderly and stereotyped manner, with only little variation. In the present experiments, a bundle of axons running between two of the segmental ganglia has been severed and allowed to regenerate. Subsequently, the axons reestablish synaptic connections between certain identified nerve cells in the adjacent ganglia, selectively and accurately. Thus, individual sensory cells in one ganglion show a high degree of neural specificity in reestablishing cell to cell connections with a motor cell in the next ganglion. The performance of the regenerated synapses, however, is significantly altered in a consistent manner. The normal balance between the effects of inhibitory and excitatory innervation in leeches with regenerated synapses is different from that seen in normal leeches, with marked overemphasis on inhibition. Similar alterations have also been seen in a series of ganglia at a distance from the site of the lesion. After the operation, therefore, a widespread modification of synapses occurs along the length of the nerve cord.
Cochlear Structure in the Dolphin,
Lagenorhynchus obliquidens
Authors: Wever Ernest Glen , McCormick James G. , Palin Jerry , Ridgway Sam H.
Published: May 2006

The cochleas of five specimens of the Pacific white-sided dolphin,
Lagenorhynchus obliquidens
, that had been fixed by intravital perfusion, embedded in celloidin, and sectioned in a continuous series, were studied with particular attention to the numbers and distribution of hair cells and ganglion cells. The number of inner hair cells is estimated as 3272 and the number of outer hair cells is estimated as 12,899, for a total of 16,171 cells. The ganglion-cell population is estimated as 50,412 after correction for cell splitting in the sectioning process.
Surface Photometry of Celestial Sources from a Space Vehicle: Introduction and Observational Procedures
Authors: Roach Franklin E. , Carroll Benjamin , Aller Lawrence H. , Smith Leroi
Published: May 2006

Diffuse celestial sources of relatively low surface brightness such as the Milky Way, zodiacal light, and gegenschein (or
contre lumière
) can be studied most reliably from above the earth's atmosphere with equipment flown in artificial satellites. We review the techniques used and some of the difficulties encountered in day-time observations from satellites by the use of a special photometer and polarimeter flown in the orbiting skylab observatory, OSO-6.
Circular Oligomers in Mitochondrial DNA of Human and Beef Nonmalignant Thyroid Glands
Authors: Paoletti Claude , Riou Guy , Pairault Jacques
Published: May 2006

Circular dimers and higher oligomers of mitochondrial DNA have previously only been described in tumor cells. This work demonstrates that such oligomers are also consistently found in a relatively high content (10-37% in weight) in nonmalignant human and beef thyroid glands. Therefore, these forms cannot be assumed to be specific for malignancy, even if they could be related to it in some instances.
Biological Study of a Nontoxic, Water-Soluble Immunoadjuvant from Mycobacterial Cell Walls
Authors: Chedid L. , Parant M. , Parant F. , Gustafson R. H. , Berger F. M.
Published: May 2006

Whole mycobacterial cells, which are used in Freund's complete adjuvant, besides inducing hypersensitivity to tuberculoprotein, also can elicit hyperreactivity to endotoxins, lymphoid hyperplasia, and allergic polyarthritis in rats. The data reported here demonstrate that a potent water-soluble adjuvant obtained from mycobacterial cell walls is also effective in increasing the immune response to viruses, and that it is free of the toxic effects observed with whole mycobacterial cells.
Limiting Availability of Binding Sites for Dehydrogenases on the Cell Membrane of
Escherichia coli
Authors: Kung Hsiang-Fu , Henning Ulf
Published: May 2006

Experiments are reported that demonstrate that in
E. coli
the pyridine nucleotide-independent D- and L-lactate dehydrogenases and the aerobic L-α-glycerophosphate dehydrogenase are membrane bound. These enzymes differed from succinate dehydrogenase in that they could be solubilized by treatment with nonionic detergent while succinate dehydrogenase could not. The binding of these enzymes to membrane was measured in mutants constitutive for the synthesis of various dehydrogenases: in cells in which the amount of dehydrogenases synthesized was greater than in others, the enzymes described above (except succinate dehydrogenase) were found in part in the soluble fraction of the cell extracts. Experiments of oxygen uptake indicate that when a fraction of the enzymes became soluble, this soluble fraction is no longer functional in respiration. These results indicate that it is possible to prevent membrane attachment of certain dehydrogenases by the excess production of other dehydrogenases; it may be that dehydrogenases compete for identical binding sites.
Reversibility of the Tryptophanase Reaction: Synthesis of Tryptophan from Indole, Pyruvate, and Ammonia
Authors: Watanabe Takehiko , Snell Esmond E.
Published: May 2006

Degradation of tryptophan to indole, pyruvate, and ammonia by tryptophanase (EC 4....) from
Escherichia coli
, previously thought to be an irreversible reaction, is readily reversible at high concentrations of pyruvate and ammonia. Tryptophan and certain of its analogues, e.g., 5-hydroxytryptophan, can be synthesized by this reaction from pyruvate, ammonia, and indole or an appropriate derivative at maximum velocities approaching those of the degradative reactions. Concentrations of ammonia required for the synthetic reactions produce specific changes in the spectrum of tryptophanase that differ from those produced by K
+
and indicate that ammonia interacts with bound pyridoxal 5′-phosphate to form an imine. Kinetic results indicate that pyruvate is the second substrate bound, hence indole must be the third. These results favor a modified mechanism for the multitude of tryptophanase-catalyzed reactions in which α-aminoacrylate, which functions as a common enzyme-bound intermediate in both synthetic and degradative reactions, is not released into the medium during the latter reactions, but is degraded to pyruvate and ammonia by sequential reversible steps via enzyme-bound intermediates.
The Size of Localized States Near the Mobility Edge
Authors: Anderson P. W.
Published: May 2006

The “mobility edge” is the critical point at which a transition from localized to extended character of the eigenfunctions occurs in the random lattice problem. We study the behavior of the eigenfunctions as this critical point is approached, and produce arguments that suggest that they fall off, on the average, as exp(-α)
R
with range
R
, and that α α [
E
-

E
c

]
0.6
Powers of Representations of the Rotation Group (Their Symmetric, Alternating, and Other Parts)
Authors: Murnaghan Francis D.
Published: May 2006

It has been known for more than three quarters of a century that the square of the irreducible representation
D
(
j
), of dimension 2
j
+ 1, of the 3-dimensional rotation group
R
3
contains the representations
D
(2
j
),
D
(2
j
- 1),...,
D
(1),
D
(0) of
R
3
, each occurring once. I give in this paper a method, involving no more than the expansion of (1 +
x
+... +
x

2
j

)

n
-1

, of analyzing (
D
(
j
))

n

, the
n
th power of
D
(
j
),
n
= 3, 4, 5,..., into the sum of the irreducible representations
D
(
nj
),
D
(
nj
- 1),...,
D
(1),
D
(0) of
R
3
, each occurring a stated number of times. When
n
= 2, the part
D
(2
j
) +
D
(2
j
- 2) +... +
D
(2) +
D
(0) of (
D
(
j
))
2
is associated with the partition (2) of 2 and is termed the
symmetric
part of (
D
(
j
))
2
, while the remaining part,
D
(2
j
- 1) +
D
(2
j
- 3) +... +
D
(3) +
D
(1), of (
D
(
j
))
2
is associated with the partition (1
2
) of 2 and is termed the
alternating
part of (
D
(
j
))
2
. For any value of
n
, (
D
(
j
))

n

contains various parts, each associated with a
k
-part partition of
n
, where
k
≤ 2
j
+ 1, the part associated with the l-part partition (
n
) of
n
being termed the symmetric part of (
D
(
j
))

n

and the part associated with the
n
-part partition (1

n

) of
n
, where
n
≤ 2
j
+ 1, being termed the alternating part of (
D
(
j
))

n

. If
n
> 2
j
+ 1, (
D
(
j
))

n

has no alternating part. I show how to determine these various parts giving full details when
j
= 1 and
n
is arbitary, and when
j
is arbitrary and
n
= 3 or 4. I also show that when
n
= 2
m
+ 1 is odd the alternating part of (
D
(
j
))

n

is, when it exists, i.e., when
m
≤
j
, the same as the symmetric part of (
D
(
j
-
m
))

n

and that the alternating part of (
D
(
j
))

n

is the same as the alternating part of (
D
(
j
))

n′

, where
n
+
n′
= 2
j
+ 1. This implies that, when
n
is even and <2
j
+ 1, the alternating part of (
D
(
j
))

n

is the same as the symmetric part of (
D
(
n
/2))

2
j
+1-
n

.
Gyrinidal: A Sesquiterpenoid Aldehyde from the Defensive Glands of Gyrinid Beetles
Authors: Meinwald J. , Opheim K. , Eisner T.
Published: May 2006

Three species of gyrinid beetles (
Gyrinus ventralis, Dineutes hornii
, and
D. serrulatus
) have been found to produce the nor-sesquiterpenoid aldehyde
gyrinidal
in the secretion of their pygidial defensive glands. This highly functionalized terpene is shown to be (E,E,E)-3,7-dimethyl-8,11-dioxo-2,6,9-dodecatrienal on the basis of spectral evidence and chemical degradation. While a very wide range of sesquiterpenoid structures occur in nature, gyrinidal appears to be the most highly oxidized acyclic sesquiterpene known.
A Limit Theorem on the Cores of Large Standard Exchange Economies
Authors: Brown Donald J. , Robinson Abraham
Published: May 2006

This note introduces a new mathematical tool, nonstandard analysis, for the analysis of an important class of problems in mathematical economics—the relation between bargaining and the competitive price system.
Pseudo-Poles in the Theory of Emden's Equation
Authors: Hille Einar
Published: May 2006

It is known that Emden's equation
y
″ =
x

1-
m

y
m

has movable singularities where the solution becomes infinite for one-sided approach. If
m
= (
p
+ 2)/
p
,
p
positive integer, the singularities look like poles of order
p
. In this note expansions in terms of powers and logarithms are obtained from which the nonpolar nature of these “pseudo-poles” becomes evident. Various extensions are considered. Convergence proofs are deferred to a more detailed publication.
Location of Ribosomal Protein Binding Sites on 16S Ribosomal RNA
Authors: Zimmermann Robert A. , Muto Akira , Fellner Peter , Ehresmann Chantal , Branlant Christiane
Published: May 2006

The distribution of ribosomal protein binding sites on the 16S ribosomal RNA molecule has been analyzed by limited ribonuclease hydrolysis of RNA-protein complexes, as well as by the interaction of individual proteins with RNA fragments purified from partial enzymatic digests. Of the six 30S subunit proteins known to interact directly with 16S RNA, proteins S4, S8, S15, S20, and, probably, S13 bind within a fragment produced by T
1
RNase (12S RNA) that comprises some 900 nucleotides and covers almost the entire 5′-terminal half of the 16S molecule. A fragment of 500-600 nucleotides (8S RNA) that is contiguous with 12S RNA and arises from the 3′-terminal portion of the 16S molecule is believed to contain the binding site for protein S7. Protein S15 interacts specifically with a sequence of about 135 nucleotides (4S RNA) that derives from 12S RNA after more extensive hydrolysis. Protein S4, but none of the other ribosomal proteins, binds to a 500-nucleotide fragment (9S RNA), generated by pancreatic RNase, that lies at the 5′-terminus of 16S RNA and is completely overlapped by the 12S fragment. A preliminary map of the binding sites is presented.
3-Cyclic Amine Derivatives of Rifamycin: Strong Inhibitors of the DNA Polymerase Activity of RNA Tumor Viruses
Authors: Green Maurice , Bragdon Janice , Rankin Anne
Published: May 2006

Derivatives of rifamycin-SV with substituted cyclic-amine side chains in position 3 of the ansa ring are strong inhibitors of RNA-directed DNA and DNA-directed DNA polymerase activity of RNA tumor viruses of murine, feline, and avian origin. Among 37 3-amine derivatives of rifamycin-SV that were tested, 29 3-cyclic amine derivatives were good inhibitors of the viral polymerases. Especially active were 3-piperidyl derivatives of rifamycin-SV with cyclohexyl and cyclohexylalkyl substituents. Derivatives that were effective against the viral polymerase also blocked cell transformation by the murine sarcoma virus. A DNA-directed DNA polymerase preparation from human KB cells was less sensitive to inhibition by these derivatives than the virion polymerase.
Amphetamines: Correlation of Activity with Stability of Molecular Complexes
Authors: Sung Ming-Ta , Parker John A.
Published: May 2006

Molecular complexes have been prepared from several biologically active methoxyamphetamines and 1,4-dinitrobenzene. The association constants of these complexes, determined by nuclear magnetic resonance measurements, correlate linearly with the threshold hallucinogenic dose in humans.
Variable Decay of Memory and Its Recovery in Cycloheximide-Treated Mice
Authors: Squire Larry R. , Barondes Samuel H.
Published: May 2006

Mice were trained in an automated visual-discrimination task. When injected with cycloheximide before training, mice showed: (
a
) some impairment of memory within minutes after the beginning of training, (
b
) gradual development of total amnesia in less than 3 hr or in more than 6 hr after training, depending on the extent of training, and (
c
) spontaneous recovery of memory within 3 days after training. The results are consistent with the operation of three processes of memory storage: (
i
) a short-term process that is independent of protein synthesis, (
ii
) a long-term that is dependent on protein synthesis, and (
iii
) a slow-developing memory storage that becomes apparent during the days after training.
Compositional Heterogeneity of Human Heterochromatin
Authors: Hsu T. C. , Arrighi Frances E. , Saunders Grady F.
Published: May 2006

When human genome was fractionated by thermal elution chromatography, repetitious DNA was found in every arbitrary temperature segment. When these repetitious DNA families were used for
in situ
hybridization, the following conclusions were evident: (
a
) Unlike the case of mouse, where essentially all centromeric heterochromatins appear to be composed of one DNA family, human heterochromatin is composed of various DNA families. (
b
) Some human heterochromatin pieces, (e.g., that of chromosome 9) appear to have more heterogeneous composition than others (e.g., that of chromosome 1). (
c
) The highly repetitious human DNA fractions are located primarily at the centromeric and telomeric regions, but the interstitial regions also contain these fractions. (
d
) The more slowly reassociating repetitious sequences are distributed over the length of the chromatid, with a slight bias in favor of the telomeric regions. (
e
) The repetitious DNA fractions of higher (guanine + cytosine) content have less affinity for the centromeric regions.
Genetic and Physicochemical Characterization of
Escherichia coli
Strains Carrying Fused F′ Elements Derived from KLF1 and F57
Authors: Willetts Neil , Bastarrachea Fernando
Published: May 2006

Although the two F′ elements, F57 (carrying
his
+
) and KLF1 (carrying
leu
+
), cannot normally coexist in the same cell, crosses between RecA
-
strains of
Escherichia coli
carrying these two elements gave rise, at a low frequency, to progeny carrying both the
his
+
and
leu
+
markers in an extrachromosomal state. Genetic studies showed that the
his
+
and
leu
+
markers were now linked, and centrifugation studies of F′ DNA isolated from these strains confirmed the presence of a new species of DNA molecule of altered size. It is proposed that the
his
+
and
leu
+
genes in these strains are covalently linked on a single “fused” F′ element.
A Molecular Theory of Ion-Conducting Channels: A Field-Dependent Transition Between Conducting and Nonconducting Conformations
Authors: Urry D. W.
Published: May 2006

Structural and conformational requirements for an electric field-dependent transition between conducting and nonconducting macromolecular systems are: two kinetically interconvertible and energetically similar conformations, one conducting and the other nonconducting, which have axes spanning the lipid layer of biological membranes, but which have different net dipole moments along those axes. Two examples are described. A previously defined helix, the π
6
LD-helix now termed the β
6
3,3
-helix, is proposed as the conducting species, and the linear peptide correlate of the cyclic hexapeptide conformation containing two β-turns and an inversion element of symmetry is proposed as a nonconducting species. The latter is termed an anti-β
6
2
-spiral and contains little or no net dipole moment per turn, whereas the β
6
3,3
-helix contains a net dipole moment along the helix axis of about 0.5 Debye per dipeptide unit. A related conducting and nonconducting pair with large net dipole moments of opposite sign, termed syn-β
6
2
-spiral and β
6
2,4
-helix, are also described. The spiral conformations are stabilized in a lipid layer by intermolecular hydrogen bonds, leading to a linear association of transmembrane structures. A conformational transition in one member of the array could lead to destabilization of an adjacent member of the array. The conformational analysis uses a concept of cyclic conformations with linear conformational correlates. The anti-β
6
2
-spiral and β
6
3,3
-helix are derivable from the conformations of the cyclic structure [unk], whereas the syn-β
2
-spiral and β
6
2,4
-helix may be derived from the cyclic structure [unk].

The conformational analysis leads to the expectation that
N
-formyl-(L-Ala-L-Ala-Gly)

n

would form conducting channels.
Replication of Bacteriophage M 13: Inhibition of Single-Strand DNA Synthesis by Rifampicin
Authors: Staudenbauer Walter L. , Hofschneider Peter Hans
Published: May 2006

Synthesis of single-stranded DNA of bacteriophage M 13 is blocked by rifampicin. This inhibition is not observed in an
Escherichia coli
mutant possessing an RNA polymerase resistant to rifampicin. Since rifampicin stops single-strand synthesis faster than chloramphenicol, inhibition by rifampicin does not seem to result from a transcriptional block of protein synthesis, particularly in view of the long half-life of the messenger RNA for M 13. It is, therefore, concluded that the interaction of rifampicin with RNA polymerase directly affects single-strand DNA synthesis. Possible mechanisms are discussed.
ω-Theorems for Riemann's Zeta-Function at Harmonic Combinations of Points
Authors: Levinson Norman
Published: May 2006

For integer
r
≥ 2 there are arbitrarily large
T
for which [Formula: see text] With
s
= σ +
it
, corresponding results hold for σ =
c
, 1/2 ≤
c
< 1, and for 1/ζ(1 +
it
). A similar result holds for [Formula: see text]