bluuebunny/crossref_metadata_2025 huggingface dataset:
Angiotensin-Converting Enzyme from Rabbit Pulmonary Particles
Authors: Soffer R. L. , Reza R. , Caldwell P. R. B.
Published: May 2006

Angiotensin-converting enzyme has been solubilized from rabbit pulmonary particles and purified to homogeneity. The molecular weight of the native enzyme was estimated to be about 136,000 by glycerol gradient centrifugation, and a value of 140,000 was obtained for the reduced denatured protein by disc-gel electrophoresis in the presence of sodium dodecyl sulfate and 2-mercaptoethanol. The enzyme was found to be a glycoprotein with carbohydrate accounting for approximately 16% of its dry weight. The major sugar residues were identified as galactose,
N
-acetylglucosamine, and mannose, with smaller amounts of fucose and sialic acid. The homogeneous enzyme catalyzed the release of His-Leu from the COOH-terminus of angiotensin I and of Phe-Arg and Ser-Pro from that of bradykinin.
Prevention of Malignant Change in Mammalian Cells During Prolonged Culture
In Vitro
Authors: Goldblatt Harry , Friedman Libby
Published: May 2006

Mixed cultures of epithelial cells and fibroblasts, derived from primary cultures of the skin of embryo rats, grown always in rubber-stoppered T-60 flasks, first yielded a transplantable tumor from the 52nd passage, at the end of 13 months of frequently repeated subculture. A group of subcultures, derived from the 22nd passage, grown under the same medium, with the addition of 1% oxyhemoglobin, failed to yield a tumor in 23 months of repeated subculture. A return of these cultures to the regular medium with oxyhemoglobin, yielded a tumor in 4 months, after 12 more passages. Cultures of transformed cells that had regularly yielded a transplantable tumor, for 6 years, up to the 305th passage, continued to yield transplantable tumors when 1% oxyhemoglobin was added to the medium. The cells remained highly atypical, microscopically, and there was no indication of reversal of the malignancy. Although oxyhemoglobin in the medium of cell cultures seems to have had the ability to keep malignancy in abeyance, it did not reverse the established malignant transformation of the cells.
The Alcohol Dehydrogenases of
Drosophila melanogaster:
Frequency Changes Associated with Heat and Cold Shock
Authors: Johnson F. M. , Powell Ann
Published: May 2006

Laboratory populations of
Drosophila melanogaster
were subjected to heat and cold shock of sufficient duration and intensity to cause about 90 percent mortality. Alcohol dehydrogenase phenotypes were determined in survivors and controls. Significant changes in phenotypic frequencies occurred as a result of both treatments such that relative fitness appeared to be dependent on temperature. The alcohol dehydrogenase phenotype most frequently surviving heat under laboratory conditions is the same phenotype as that previously found to be higher in frequency in natural populations in areas with higher average temperature.
Temporal Changes in Embryonal Cell Surface Recognition
Authors: Gottlieb David I. , Merrell Ronald , Glaser Luis
Published: May 2006

Plasma membranes have been prepared from optic tectum and neural retina of chick embryos. These membranes specifically inhibit the aggregation of homotypic cells. Plasma membranes prepared from each of these regions obtained from chick embryos at 7,8, and 9 days of development show specificity for homotypic cells of the same age and cross-react weakly with homotypic cells of different ages. Thus cell-surface recognition changes with age of development, and most of the cells in each region have a common cell-surface recognition specificity. Tectal cells react weakly with retinal cell membranes, but no inhibition of retinal cell aggregation by tectal cells has been noted.
Isolation and
In Vitro
Translation of δ-Crystallin mRNA from Embryonic Chick Lens Fibers
Authors: Zelenka Peggy , Piatigorsky Joram
Published: May 2006

Of the protein synthesized and accumulated during differentiation of embryonic chick lens fibers, 70-80% is the tissue specific protein δ-crystallin. We have isolated and partially characterized the total cytoplasmic mRNA from purified lens fibers of 15-day-old embryos as an initial step toward understanding the regulated expression of δ-crystallin during development. Each lens fiber mass contained an average of 10 μg of cytoplasmic RNA; approximately 0.1 μg per fiber mass was recovered in the mRNA fraction by oligo(dT)-cellulose chromatography. The mRNA electrophoresed primarily as a single peak on a polyacrylamide-agarose gel with an apparent molecular weight of about 9 × 10
5
estimated by comparison with 28S and 18S rRNA markers. Of the protein synthesized in response to the mRNA in cell-free systems derived from Krebs II ascites tumor cells or rabbit reticulocytes, 70-80% comigrated with δ-crystallin on sodium dodecyl sulfatepolyacrylamide-agarose gels. Comparison of the tryptic peptides of δ-crystallin with those of the
in vitro
products from both heterologous systems established that the lens fiber mRNA contained δ-crystallin mRNA, and that no other functional mRNAs were present in detectable quantities. Thus, the specialization of protein synthesis in embryonic chick lens fibers apparently results from an accumulation of δ-crystallin mRNA in the cytoplasm.
An Invariant for Certain Operator Algebras
Authors: Carey Richard W. , Pincus Joel D.
Published: May 2006

It is shown that the so-called principal function invariant, which is associated in a unitarily invariant way to operators with trace class self commutator
TT
*
-
T
*
T
, is invariant under trace class perturbations of
T
and is an extension of the index of
T-z
to the whole plane. The connection of the principal function, under additional hypothesis, with the determination of the maximal ideal space of the
C
*
algebra generated by
T
is discussed, and it is shown that the principal function, even when it takes noninteger values, plays a role in establishing the existence of invariant subspaces for
T
and in determining the point spectrum of
T
.
Von Willebrand Factor: Gene Dosage Relationships and Transfusion Response in Bleeder Swine—a New Bioassay
Authors: Griggs Thomas R. , Webster William P. , Cooper Herbert A. , Wagner Robert H. , Brinkhous K. M.
Published: May 2006

Aggregation of human platelets by bovine plasma was recently recognized as a marker for the study of the antihemophilic and von Willebrand factors. A similar marker in porcine plasma is shown to be specific for the platelet-active von Willebrand factor of plasma, but not for the antihemophilic factor (factor VIII). A new quantitative assay for the von Willebrand factor is based on the dose-response relationship observed between the concentration of von Willebrand factor and platelet aggregation times determined macroscopically. Bleeder swine, homozygous for von Willebrand disease, had no detectable platelet aggregating activity, while heterozygotes, carriers of the disease, had reduced levels of approximately 50% of normal. Exact detection of non-obligate carriers, hitherto impossible, becomes readily feasible because of the gene dosage relationship to the von Willebrand factor plasma levels. Transfusion of bleeder swine with normal plasma results in an immediate post-transfusion rise of the von Willebrand factor, followed by a rapid falloff. At 24 hr post-transfusion, no von Willebrand factor is detectable at a time when the factor VIII response is at its maximum. The discordance in plasma levels of this platelet-active von Willebrand factor and factor VIII in carrier animals and in the bleeder animals after transfusion suggests a different molecular and genetic basis for these two biological activities.
Purification and Characterization of Acetylcholine Receptor-I from
Electrophorus electricus
Authors: Chang Hai Won
Published: May 2006

A Triton X-100 extract of electric tissue was subjected to a single step affinity chromatography using either of two affinity gels: [
N
-(6-aminocaproyl)-
p
-aminobenzyl]trimethylammonium bromide or methyl[(6-aminocaproyl-6′-aminocaproyl)-3-amino]pyridinium bromide attached to Sepharose 4B. Specific elution of the acetylcholine receptor-I (AcChR-I) with low concentration of a bis-quaternary agonist, 3,3′-bis[α-(trimethylammonium)methyl]-azobenzene bromide (Bis-Q), gave a 35% yield of toxin-binding components in the crude extract. The purified AcChR-I readily underwent aggregation, which appeared to arise from the oxidation of titratable free sulfhydryl on the protein. The protein was characterized by the binding capacities for [
125
I]α-bungarotoxin (α-Bgt), [
3
H]acetylcholine, and [
14
C]Bis-Q; the ratio of these capacities were approximately 2:1:2, respectively, with 5-6:5 nmole of α-Bgt sites per mg of protein. Analysis by sodium dodecyl sulfate gel electrophoresis of the disulfide-reduced and nonreduced polypeptide components indicated that a 41,500 dalton species was the major subunit component of AcChR-I. The binding of [
14
C]Bis-Q with a Triton X-100 crude extract showed sites with both high and low dissociation constants, whereas purified AcChR-I contained only high-affinity sites. A biphasic double-reciprocal plot and a Hill coefficient of 0.7 suggested negative cooperativity in the binding of Bis-Q with the purified AcChR-I.
Effect of Insulin on Sterol and Fatty Acid Synthesis and Hydroxymethylglutaryl CoA Reductase Activity in Mammalian Cells Grown in Culture
Authors: Bhathena Sam J. , Avigan Joel , Schreiner Marta E.
Published: May 2006

The effects of insulin on the synthesis of sterols and fatty acids and on the activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase (EC 1.1.1.34), a rate-limiting enzyme for sterol synthesis, were studied in mammalian cells grown in culture. While in some established cell lines sterol synthesis was not affected significantly by the hormone, in the nonpermanent human and animal cells the synthesis of lipids, especially that of sterols, as well as the activity of the reductase were stimulated following an incubation with insulin in a medium containing serum albumin for a few hours or longer. These effects of insulin were also demonstrable in the presence of solvent-extracted serum, which itself increases sterol synthesis and reductase activity. In medium containing whole serum insulin was ineffective. Addition of glucose decreased sterol synthesis as well as reductase activity. The effects of insulin were prevented by cycloheximide and are probably due to an increased synthesis of 3-hydroxy-3-methylglutaryl CoA reductase or of a protein that regulates its activity.
Interaction of Benzodiazepines with Central Nervous Glycine Receptors: Possible Mechanism of Action
Authors: Young Anne B. , Zukin Stephen R. , Snyder Solomon H.
Published: May 2006

Interaction of 21 benzodiazepines with the glycine receptor in the brainstem and spinal cord of rat have been evaluated in terms of their displacement of [
3
H]strychinine binding. The rank order of potency of the 21 drugs in displacing specific [
3
H]strychinine binding correlates (p < 0.005) with their rank order of potency in a vareity of pharmacological and behavioral tests in humans and animals that predict clinical efficacy. There is a 50-fold variation in potency of the series of benzodiazepines with mean effective dose (ED
50
) values ranging from 19μM to > 1000 μM. Diazepam (Valium®) and chlordiazepoxide (Librium®) have ED
50
's of 26 μM and 200 μM, respectively, whereas the ED
50
for glycine is 25 μM. The inhibitory effects of 10 of the agents in two other central nervous system membrane receptor assays, for the opiate receptor and the muscarinic cholinergic receptor, do not correlate with any of the
in vivo
pharmacologic and behavioral tests. The benzodiazepines may exert their antianxiety, anticonvulsant and muscle-relaxant effects by mimicking the effects of the neurotransmitter glycine at its central nervous system receptor sites.
The Somatic Cell Genetics of Human Interferon: Assignment of Human Interferon Loci to Chromosomes 2 and 5
Authors: Tan Y. H. , Creagan R. P. , Ruddle F. H.
Published: May 2006

A total of 40 mouse-human cell hybrids were induced with poly(I)·poly(C) and with Newcastle disease virus. Ten hybrid clones produced low levels of human interferon in response to both the virus and poly(I)·poly(C). Concurrent enzymic and chromosomal analysis of the hybrid clones indicated a concordant segregation of these levels of human interferon with chromosomes 2 and 5. The presence of both chromosomes 2 and 5 was necessary for interferon production; neither was sufficient alone. Based on this finding, we postulate that there are at least two asyntenic gene loci for the expression of interferon in human cells.
The Location of the Repressor Binding Sites in the
lac
Operon
Authors: Reznikoff William S. , Winter Robert B. , Hurley Carolyn Katovich
Published: May 2006

The affinity of various mutant
lac
DNAs for the
lac
repressor was examined by means of a competition binding assay. The results indicate that there exist at least two binding sites for the
lac
repressor. The primary binding site is coincidental with the operator, as defined by genetic studies. Mutations of the promoter or the
Z
gene have little or no effect on the repressor binding properties of this primary binding site, thereby confirming that the operator is distinct from
lacP
and
Z
. The secondary binding site(s), which has a 25- to 31-fold lower affinity for the repressor, is located within the operator proximal third of the
Z
gene.
Effects of Dialyzable Transfer Factor in Patients with Breast Cancer
Authors: Oettgen H. F. , Old L. J. , Farrow J. H. , Valentine F. T. , Lawrence H. S. , Thomas L.
Published: May 2006

Five patients with advanced breast cancer were treated with pooled dialyzable transfer factor from healthy adult donors. The period of treatment ranged from 21 to 310 days, the total dose from 20 to 257 ml. Transfer factor did not elicit inflammatory or hypersensitivity reactions or detectable formation of antibody to itself, nor any hematological or biochemical abnormalities or other side effects. Three patients became responsive (by skin test) to tuberculin and/or streptococcal antigens. Marked partial regression of the breast cancer, lasting 6 months, was observed in one patient.
Photoaffinity Labeling of the Ouabain-Binding Site on (Na
+
+ K
+
) Adenosinetriphosphatase
Authors: Ruoho Arnold , Kyte Jack
Published: May 2006

An ethyl diazomalonyl derivative of cymarin was synthesized in order to photoaffinity label the cardiac glycoside-binding site on (Na
+
+ K
+
) adenosinetriphosphate (EC 3.6.1.3). When a noncovalent complex of the enzyme and this cardiac glycoside derivative was photolyzed, a covalent bond was formed between the ligand and the larger of the two polypeptide subunits of the enzyme. Several control experiments demonstrate that this photochemical reaction occured while the ligand was bound to the site at which it inhibits the enzyme activity. Another specific inhibitor, tentatively identified as the ethyl chloromalonyl derivative of cymarin, produced similar photoaffinity labeling of the larger subunit, demonstrating that the photolytic dissociation of the diazo group may not be responsible for the photochemical reaction. Since the cardiac glycoside-binding site, which is accessible from the outside surface of the plasma membrane, and the phosphorylation site, which is accessible from the inside surface, are both on the larger polypeptide subunit of (Na
+
+ K
+
) adenosinetriphosphatase, this polypeptide has sequences exposed to both sides of the membrane.
Activity of Empty, Headlike Particles for Packaging of DNA of Bacteriophage λ
In Vitro
Authors: Hohn B. , Hohn T.
Published: May 2006

A precursor head of phage lambda is synthesized after induction of cells lysogenic for λ

D
-
F
-

and λ
A
-
(head-defective) mutants. This precursor head can be assayed by complementation
in vitro
and can be purified by CsCl gradient centrifugation and sucrose gradient sedimentation. The precursor head contains no DNA and has the same dimensions as the petit λ particle. It can be packed with λ DNA in an extract from induced
Escherichia coli
lysogenic for a λ
E
-
mutant.
Regulation of Adenylate Kinase and Creatine Kinase Activities in Myogenic Cells
Authors: Tarikas Helgi , Schubert David
Published: May 2006

The regulation of the specific activities of adenylate kinase (EC 2.7.4.3) and creatine kinase (EC 2.7.3.2) in myogenic cell lines is independent of cell fusion. The observed increases in enzyme specific activities are cell density dependent, and may be further broken down into contributions from an increase in enzyme activity per cell and a decrease in protein per cell. Only the former appears to be affected by medium conditioning.
Composition and Activity of the Photosynthetic Apparatus in Temperature-Sensitive Mutants of Higher Plants
Authors: Alberte R. S. , Hesketh J. D. , Hofstra G. , Thornber J. P. , Naylor A. W. , Bernard R. L. , Brim C. , Endrizzi J. , Kohel R. J.
Published: May 2006

Six nuclear mutants of corn, six of soybean, and seven of cotton displayed low temperature-induced virescence when grown in controlled environments. For the group of plants studied, an increase in leaf chlorophyll
a/b
ratio was correlated with a temperature-sensitive biosynthetic sequence leading to a reduction in total chlorophyll content. These pigment alterations were reflected in the composition and quantity of the two major chlorophyll-protein complexes of chloroplast membranes. Changes in the amount of the major light-harvesting chlorophyll-protein complex was a prime consequence of the nuclear mutations. A decrease in the light-harvesting chlorophyll component of the light reaction centers of the leaf may account for the decrease in size of the photo-synthetic unit frequently noted in chlorophyll-deficient mutants. Variations in the concentration of the chlorophyll-protein complexes in the chloroplast lamellae may be causally related to variations in CO
2
compensation points of mutant soybean and cotton plants.
Selection for Neuroblastoma Cells that Synthesize Certain Transmitters
Authors: Breakefield Xandra O. , Nirenberg Marshall W.
Published: May 2006

A selection procedure was devised for neurons and related cells that depends upon the ability of the cells to synthesize certain amine neurotransmitters. The rationale for selection is that tyrosine is an essential amino acid for most mammalian cells and that three enzymes from mammalian sources can catalyze the synthesis of tyrosine: phenylalanine hydroxylase (EC 1.14.16.1), tyrosine hydroxylase (EC 1.14.16.2), and tryptophan hydroxylase (EC 1.14.16.4). Tyrosine hydroxylase is found predominantly in adrenergic neurons and related cells that synthesize dopamine, norepinephrine, and epinephrine, and tryptophan hydroxylase in cells synthesizing serotonin or melatonin. Only 1 out of 70,000 uncloned mouse neuroblastoma cells grew well in the absence of tyrosine. Approximately 50% of the cell lines obtained by selection had tyrosine hydroxylase activity. This selection procedure thus provides a simple means of obtaining cell lines of neural origin on the basis of their ability to synthesize putative transmitters.
Thymosin Corrects the Abnormal DNA Synthetic Response of NZB Mouse Thymocytes
Authors: Dauphinee Michael J. , Talal Norman , Goldstein Allan L. , White Abraham
Published: May 2006

New Zealand Black (NZB) mice develop after 16 weeks of age an autoimmune and lymphoproliferative disease which is a model for systemic lupus erythematosus and lymphoid malignancy in humans. At this age, the mice manifest a progressive decline in T lymphocyte (thymus-derived lymphocyte) functions and serum thymosin levels. Thymocytes from 8-week old NZB mice exhibit an abnormal DNA synthetic response when transplanted into lethally irradiated C57B1/6 recipients. DNA synthesis (measured as the incorporation of radioactively labeled 5-iodo-2′-deoxyuridine) is delayed in onset and still increasing 6 days after cell transfer. By contrast, 2-week old NZB thymocytes show a normal response which is rapid in onset and completed by day 6.

NZB mice were injected with thymosin fraction 5 or with bovine serum albumin starting at 2 weeks of age. Thymocytes from 8-week old thymosin-treated mice showed a normal DNA synthetic response, whereas the albumin-treated controls showed the abnormal response expected at this age. The ability of thymosin to correct the DNA synthetic response was related to dose and duration of treatment. These results suggest that thymosin can induce a more normal state of thymocyte differentiation in NZB mice. If abnormal thymocyte differentiation is related to the subsequent emergence of autoimmunity and lymphoid malignancy, then continuous treatment with thymosin may have therapeutic potential. These experiments suggest that an endocrine disturbance may contribute to autoimmune and lymphoproliferative disease in NZB mice and possibly in humans.
Nonasymptotic Species Richness Models and the Insects of British Trees
Authors: Strong Donald R.
Published: May 2006

Nonasymptotic models of species diversity are those that do not consider negative feedback between number of species in a biota and the net rate of species addition. These models propose species richness differences to be primarily the product of geologic age differences among biotas. Nonasymptotic explanations are traditional for various diversity difference spectra, including latitudinal diversity gradients and the greater species richness of ancient compared to young lakes. I review new evidence that renders these nonasymptotic explanations doubtful.

The only uncontested evidence in favor of nonasymptotic species accumulation is Southwood's correlation between the number of insect species associated with British tree taxa and the number of Quaternary fossil records of these taxa. I show that nonasymptotic explanations of species richness variation are unacceptable for this system also. The variation in insect species richness among these taxa is well accounted for by a species-area relationship. The species richness asymptote is attained within a few hundred years, and the influence of cumulative host taxon abundance (number of fossil records) upon insect species richness is insignificant after the statistical influence of present-day host plant range is removed. I conclude Southwood's correlation to lack causality; it probably derives from a correlation between the number of fossil records of the host taxa and their present range.
In Vitro
Synthesis of Rous Sarcoma Virus-Specific RNA is Catalyzed by a DNA-Dependent RNA Polymerase
Authors: Rymo L. , Parsons J. T. , Coffin J. M. , Weissmann C.
Published: May 2006

Synthesis of Rous sarcoma virus RNA was examined
in vitro
with a new assay for radioactive virus-specific RNA. Nuclei from infected and uninfected cells were incubated with ribonucleoside [α-
32
P]triphosphates, Mn
++
, Mg
++
and (NH
4
)
2
SO
4
. Incorporation into total and viral RNA proceeded with similar kinetics for up to 25 min at 37°. About 0.5% of the RNA synthesized by the infected system was scored as virus-specific, compared to 0.03% of the RNA from the uninfected system and 0.005% of the RNA synthesized by monkey kidney cell nuclei. Preincubation with DNase or actinomycin D completely suppressed total and virus-specific RNA synthesis. α-Amanitin, a specific inhibitor of eukaryotic RNA polymerase II, completely inhibited virus-specific RNA synthesis, while reducing total RNA synthesis by only 50%. We conclude that tumor virus-specific RNA is synthesized on a DNA template, most probably by the host's RNA polymerase II.
Increased Thermal Stability of Chromatin Containing 5-Bromodeoxyuridine-Substituted DNA
Authors: David John , Gordon Joel S. , Rutter William J.
Published: May 2006

The replacement of thymidine by 5-bromodeoxyuridine in DNA leads to a greatly enhanced stability of chromatin from hepatoma tissue culture or embryonic rat pancreas, as measured by thermal chromatography on hydroxylapatite. The increased stability is directly correlated with the degree of bromodeoxyuridine substitution. On the other hand, the incorporation of bromodeoxyuridine into DNA results in a modest stabilization of purified DNA. Substitution of nucleotide also alters slightly the hyperchromicity profile generated during the thermal denaturation of purified DNA and chromatin. The observed changes can best be explained by an altered interaction between the bromodeoxyuridine-DNA and other chromatin components, presumably proteins. These results suggests that the selective effects of bromodeoxyuridine on cytodifferentiation may be due to an increased affinity of regulatory proteins for bromodeoxyuridine-DNA.
Antipsychotic Drugs and Dopamine-Stimulated Adenylate Cyclase Prepared from Corpus Striatum of Rat Brain
Authors: Karobath M. , Leitich H.
Published: May 2006

Antipsychotic drugs and their clinically impotent congeners were examined as inhibitors of dopamine-sensitive adenylate cyclase (EC 4.6.1.1) in cell-free membrane preparations of the caudate-putamen of rat brain. Of 12 neuroleptic drugs with reported antipsychotic efficacy, all inhibit stimulation of adenylate cyclase by 40 μM dopamine at micromolar concentrations. Among 14 other structurally related drugs that are not clinically effective as antipsychotic agents, 12 were almost ineffective while two drugs were moderate inhibitors of dopamine-sensitive adenylate cyclase.
Control of the Initiation of DNA Synthesis in 3T3 Cells: Low-Molecular-Weight Nutrients
Authors: Holley Robert W. , Kiernan Josephine A.
Published: May 2006

Sparse 3T3 cells, in excess serum, become quiescent in the early G
1
(or G
0
) phase of the cell cycle if the cells are cultured in low concentrations of amino acids, glucose, or phosphate ion. These quiescent cells then initiate DNA synthesis if the concentration of the limiting nutrient is increased. In normal medium, DNA synthesis in the same 3T3 cell line is controlled by serum factors. The results demonstrate the complexity of the control by external agents of DNA synthesis in these “normal,” density-dependent cells.
Procollagen: Intermediate Forms Containing Several Types of Peptide Chains and Non-Collagen Peptide Extensions at NH
2
and COOH Ends
Authors: Tanzer Marvin L. , Church Robert L. , Yaeger James A. , Wampler D. Eugene , Park Eun-Duck
Published: May 2006

A population of procollagen molecules has been isolated from the culture medium of a clonal line of calf dermatosparactic cells and shown to have the amino-acid composition, physical properties, and molecular structure consistent with collagen precursors. Although this procollagen population shares immunologic determinants with the procollagen obtained from dermatosparactic skin, it differs from the latter in aminoacid composition, in subunit properties, and by its content of
both
amino and carboxyl terminal non-collagen peptide appendages. We propose that the cell culture procollagen contains earlier biosynthetic forms of dermatosparactic procollagen.
Selective Thymic Localization of Murine Leukemia Virus-Related Antigens in C57BL/Ka Mice after Inoculation with Radiation Leukemia Virus
Authors: Declève Alain , Sato Chikako , Lieberman Miriam , Kaplan Henry S.
Published: May 2006

The tissue distribution and extent of virus-specific antigen expression were studied by immunofluorescence as a function of time and of lymphoma development in adult C57BL/Ka (Fv-1
b
) mice after intravenous injection of radiation leukemia virus, a B-tropic murine leukemia virus. Viral antigens were detected earlier in the thymus (1 week) than in the bone marrow, spleen, or lymph nodes (2-3 weeks). Despite an initial virus-induced thymic involution, the percentage of immunofluorescence-positive cells in the thymus rapidly increased thereafter to 65-80%, at which level it remained until 9 weeks, at which time increases in size and weight, histological changes, and an increased number of blastoid cells indicated the onset of lymphoma development in the thymus. In contrast, the percentage of immunofluorescence-positive cells in the bone marrow, spleen, and nodes remained low, and gradually decreased to zero within 8 weeks after thymectomy. The selective thymic localization of antigens induced by radiation leukemia virus in C57BL/Ka mice is in striking contrast to the previously reported ubiquitous tissue distribution of the Gross-AKR virus, an N-tropic virus, in its natural host, the Fv-1
n
, AKR strain with a high incidence of leukemia.
A Pleiotropic Mutation Affecting Expression of Polar Development Events in
Caulobacter crescentus
Authors: Kurn Nurith , Ammer Susan , Shapiro Lucille
Published: May 2006

A developmental mutant of
C. crescentus
with altered polar surface structures has been isolated. The mutant lacks a flagellum and pili, and may have an abnormal DNA phage receptor site. A revertant regains the normal structures simultaneously. This point mutation allows normal flagellin synthesis, stalk formation, equatorial cell division, and rate of growth. The mutant phenotype indicates that the assembly of the polar surface structures is coordinately regulated and independent of mechanisms regulating cell polarity and division.
On the Use of Mist Nets for Population Studies of Birds
Authors: MacArthur Robert H. , MacArthur Alan T.
Published: May 2006

Studies in which birds are captured in mist nets, marked, and released can yield much more information than previously realized. When nets are erected, the capture rate is initially high and then decreases with time, as more and more of the resident bird individuals in the vicinity are captured and learn to avoid the nets a second time. The capture rate eventually reaches an asymptotic value depending on the number of “drifting,” nonresident individuals in the vicinity. We describe a simple theoretical formulation of this decline in capture rate, and we show how it can be used to estimate the sizes of the resident population and the drifting population separately. To illustrate the theory, we apply it to the results of a netting study in a Vermont forest. Variation among species in capture efficiency is correlated in part with preferred vertical foraging position. Species may be characterized as “smart” or “dumb” by the criterion of relative recapture frequency.
Herpes Simplex-Genitalis Virus Nonvirion Antigens and Their Implication in Certain Human Cancers: Unconfirmed
Authors: Sabin Albert B.
Published: May 2006

The previously reported data on the existence of herpes simplex-genitalis virus nonvirion, neoantigens with distinctive properties, and on the presence of specific antibodies for these neoantigens only in the sera of specially hyperimmunized guinea pigs or of patients with certain types of cancer, could not be confirmed. Many factors that could have been responsible for the difference between the originally reported results and those recently obtained were carefully checked and investigated. The assumption that a mixture of two anticomplementary ingredients bound at least as much complement as the more anticomplementary component, and sometimes more, was found to be incorrect for the ingredients used in this work; the reverse was true. Previous failure to observe some of the strict requirements of the complement fixation test could account for some but not all of the unconfirmed previously reported data. Conclusions,
based on the unconfirmed data
, including those implicating these viruses in the etiology of certain human cancers, are therefore negated.
Selective Binding of [
3
H]Gibberellin A
1
by Protein Fractions from Dwarf Pea Epicotyls
Authors: Stoddart John , Breidenbach William , Nadeau Ronn , Rappaport Lawrence
Published: May 2006

A homogenate from dwarf pea seedlings that had been treated with [
3
H]gibberellin A
1
was separated by Sephadex G-200 into two protein fractions, of high and intermediate molecular weight, with affinity for [
3
H]gibberellin A
1
. Neither fraction bound [
3
H]gibberellin A
8
, the only metabolite of [
3
H]gibberellin A
1
detected in significant quantity in extracts of pea seedlings. These proteinhormone complexes were noncovalently bound, as evidenced by their rapid disruption in ethanol. Approximate molecular weights of the fractions were 500,000 and 60,000. In experiments designed to detect competition for the binding proteins between [
3
H]gibberellin A
1
and closely related [
3
H]gibberellin molecules, [
3
H]gibberellin A
8
and pseudo [
3
H]gibberellin A
1
were inactive, but keto [
3
H]gibberellin competed favorably. Equilibrium dialysis experiments revealed that both high-molecular-weight and intermediate-molecular-weight protein-hormone complexes could undergo hormone exchange with nonlabeled gibberellin A
1
.
Specificity of the DNA Product of RNA-Dependent DNA Polymerase in Type C Viruses: III. Analysis of Viruses Derived from Syrian Hamsters
Authors: Okabe Hiromi , Gilden Raymond V. , Hatanaka Masakazu
Published: May 2006

DNA transcripts were prepared from three related viruses of hamster and analyzed by interviral hybridization and by reaction with cellular DNA. A virus (G-HaLV), isolated from a dimethylbenzanthraceneinduced tumor cell in Graffi hamsters, contained nucleic acid sequences highly specific for hamster cell DNA and did not react with mouse cell DNA nor did its transcript show homology (<5%) with mouse or rat viral RNAs. The hamster-specific sarcoma virus, B-34, isolated by Bassin and coworkers from tumors induced by the Harvey strain of murine sarcoma virus, contained mouse-, hamster-, and possibly rat-specific sequences. B-34 transcripts were predominantly mouse-specific. GLOH
-
, a lymphomagenic virus derived by dilution beyond the transforming endpoint of a hamster-specific sarcoma virus obtained from tumors induced by the Gross pseudotype of murine sarcoma virus, also contained hamster- and mouse-specific sequences. Only a portion of its hamster sequence (about 50%) was shared with B-34 and G-HaLV viruses. As expected, transcripts of GLOH
-
virus were reactive with mouse and hamster cellular DNA.
Continuous Lymphoid Cell Lines with Characteristics of B Cells (Bone-Marrow-Derived), Lacking the Epstein-Barr Virus Genome and Derived from Three Human Lymphomas
Authors: Klein George , Lindahl Tomas , Jondal Mikael , Leibold Wolfgang , Menézes José , Nilsson Kenneth , Sundström Christer
Published: May 2006

Three exceptional cell lines have been tested for the presence of the Epstein-Barr virus genome by nucleic acid hybridization (complementary RNA·DNA) and Epstein-Barr virus-determined nuclear antigen tests. Two lines were derived from Swedish lymphoma cases and one from an African Burkitt-like lymphoma biopsy that was negative for Epstein-Barr virus DNA and the virus-determined nuclear antigen. All three lines apparently lacked the viral genome. Two of the three lines clearly had characteristics of B-cells (bone-marrow-derived).
Association of the Membrane-Penetrating Polypeptide Segment of the Human Erythrocyte MN-Glycoprotein with Phospholipid Bilayers. I. Formation of Freeze-Etch Intramembranous Particles
Authors: Segrest Jere P. , Gulik-Krzywicki T. , Sardet Christian
Published: May 2006

The membrane-penetrating segment of the surface MN-glycoprotein of the human erythrocyte is contained intact within the tryptic peptide T(is). We report here on the association of this peptide with hydrated phospholipid vesicles. Under these conditions 80 Å intramembranous particles, as seen by freeze-etch electron microscopy, are produced that are similar in size to those seen in the native erythrocyte membrane. These particles increase in number as a linear function of T(is) concentration and a plot of particle number versus concentration is compatible with a micelle-like phenomenon; from this curve the critical concentration for the formation of particles is estimated to be approximately one mole of T(is) to 120 moles of lecithin. These data suggest that the membrane-penetrating peptide T(is) is being incorporated, monomerically and multimerically, within the hydrocarbon phase of lecithin bilayers.

From these data it can be calculated that each intramembranous particle contains between 10 and 20 T(is) monomers. The peptide portion of each particle, therefore, has a molecular weight of 45,000-85,000.

An exact analogy cannot be drawn at this time between the
in vivo
structure of erythrocyte intramembranous particles and the reconstituted particles described here, although an argument has been constructed to support this possibility. What is clear is that the reconstituted system promises to be useful for further examination of protein-lipid interactions in membranes.
A New Relaxed Mutant of
Escherichia coli
with an Altered 50S Ribosomal Subunit
Authors: Friesen J. D. , Fiil N. P. , Parker J. M. , Haseltine William A.
Published: May 2006

A new relaxed mutant called
rel C
has been isolated from a

rel A
+
/rel A
+

partial diploid strain. The
rel C
mutant is unable to synthesize ppGpp or pppGpp
in vivo
in response to amino acid starvation or
in vitro
, but can synthesize these nucleotides in a shift-down.
Rel C
maps near
rif
. Studies
in vitro
demonstrate the lesion to be probably in one of the 50S ribosomal proteins that can be removed by 1.0 M LiCl.
Nucleotide Sequence Analysis of RNA Synthesized from Rabbit Globin Complementary DNA
Authors: Poon Raymond , Paddock Gary V. , Heindell Howard , Whitcome Philip , Salser Winston , Kacian Dan , Bank Arthur , Gambino Roberto , Ramirez Francesco
Published: May 2006

Rabbit globin complementary DNA made with RNA-dependent DNA polymerase (reverse transcriptase) was used as template for
in vitro
synthesis of
32
P-labeled RNA. The sequences of the nucleotides in most of the fragments resulting from combined ribonuclease T
1
and alkaline phosphatase digestion have been determined. Several fragments were long enough to fit uniquely with the α or β globin amino-acid sequences. These data demonstrate that the cDNA was copied from globin mRNA and contained no detectable contaminants.
The Nucleotide Sequence Complexity of Avian Tumor Virus RNA
Authors: Billeter M. A. , Parsons J. T. , Coffin J. M.
Published: May 2006

The nucleotide sequence complexity of 60-70S RNA of Rous sarcoma virus was determined from the molar yields of 11 pure oligonucleotides of known chain length, obtained from [
32
P]RNA of Rous sarcoma virus by T1 RNase digestion and two-dimensional polyacrylamide gel electrophoresis. We calculate an apparent chain length of about 9800 nucleotides, corresponding to a molecular weight of 3.4 × 10
6
. Assuming the molecular weight of 60-70S RNA of Rous sarcoma virus to be about 10
7
, our data suggest that the virus genome consists of identical, or very similar, nucleotide sequences repeated three to four times.
Genetic Control of Basal Serum Immunoglobulin E Level and Its Effect on Specific Reaginic Sensitivity
Authors: Marsh David G. , Bias Wilma B. , Ishizaka Kimishige
Published: May 2006

Studies of the distribution of total serum immunoglobulin E levels in nonallergic and allergic populations defined a cut-off point between low and high immunoglobulin E at 95 U/ml, based on Mendelian recessive inheritance of high immunoglobulin E level. Subsequent investigations of the distribution of total serum immunoglobulin E levels in 28 allergic families confirmed the recessive hypothesis. The results of quantitative skin tests in eight families, performed with between five and eight highly purified grass and ragweed pollen allergens per family, demonstrate that the immunoglobulin E-regulating gene exerts a profound effect on specific immunoglobulin E-mediated sensitivity, often masking the effect of HL-A associated immune response genes.
Electron Transfer Between Biological Molecules by Thermally Activated Tunneling
Authors: Hopfield J. J.
Published: May 2006

A theory of electron transfer between two fixed sites by tunneling is developed. Vibronic coupling in the individual molecules produces an activation energy to transfer at high temperatures, and temperature-independent tunneling (when energetically allowed) at low temperature. The model is compared with known results on electron transfer in
Chromatium
and in
Rhodopseudomonas spheroides
. It quantitatively interprets these results, with parameters whose scale is verified by comparison with optical absorption spectra. According to this description, the separation between linking sites for electron transfer is 8-10 Å in
Chromatium
, far smaller than earlier estimates.
Cell Surface Galactosyltransferase and Lectin Agglutination of Thymus and Spleen Lymphocytes
Authors: Lamont J. Thomas , Perrotto Joseph L. , Weiser Milton M. , Isselbacher Kurt J.
Published: May 2006

Lectin agglutination and cell surface galactosyltransferase (EC 2.4.1.67; 1-
O
-α-
D
-galactosyl-
myo
-inositol:raffinose galactosyltransferase) enzyme activity have been studied with thymus and spleen lymphocytes of neonatal rats. Thymus lymphocytes were more agglutinable by concanavalin A than by wheat germ agglutinin, whereas spleen lymphocytes were more agglutinable by wheat germ agglutinin than by concanavalin A. Thymus lymphocytes, but not spleen lymphocytes, of neonatal rats could be blast transformed by concanavalin A. Cell surface galactosyltransferase activity was present on both types of lymphocytes, but was greatly increased on thymus cells after blast transformation. The differences in lectin agglutination suggest a difference in the surface membranes of thymus and spleen lymphocytes. The increase in cell surface galactosyltransferase activity with blast transformation of thymus lymphocytes may be related to the exteriorization of the Golgi apparatus into the plasma membrane.
Recombinant DNA molecules of bacteriophage phi chi174.
Authors: Benbow R M , Zuccarelli A J , Sinsheimer R L
Published: May 2006

Phi chi174 DNA structures containing two different parental genomes were detected genetically and examined by electron microscopy. These structures consisted of two monomeric double-stranded DNA molecules linked in a figure 8 configuration. Such DNA structures were observed to be formed preferentially in host recA+ cells or recA+ cell-free systems. Since the host recA+ allele is required for most phi chi174 recombinant formation, we conclude that the observed figure 8 molecules are intermediates in, or end products of, 1 phi chi174 recombination event. We propose that recombinant figure 8 DNA molecules arise as a result of "single-strand aggression," are stabilized by double-strand "branch migration," and represent a specific example of a common intermediate in genetic recombination.
An electrophoretic variant of beta-galactosidase with altered catalytic properties in a patient with GM1 gangliosidosis.
Authors: Norden A G , O'Brien J S
Published: May 2006

In nine patients with GM1 gangliosidosis, liver ganglioside GM1 beta-galactosidase (EC 3.2.1.23) activity ranged from less than 0.01% to 0.05% of normal. In a tenth patient's liver, much higher activity was found (0.5% of normal). In this patient the residual enzyme had the same molecular weight as beta-galactosidase A, the major form of beta-galactosidase of normal human liver. No activity was found that corresponded to beta-galactosidase B, the minor form of human liver beta-galactosidase. On starch gel electrophoresis, the patient's enzyme migrated less anodally than normal beta-galactosidase A, both before and after treatment with neuraminidase. Beta-Galactosidase from the patient had a Km that was higher then normal; 5-fold higher with ganglioside GM1 and 2-fold higher with 4-methylumbelliferyl beta-galactoside. The patient's enzyme crossreacted immunologically with normal beta-galactosidase A and had about 100-fold more antigenic activity per unit catalytic activity than the normal enzyme. The results indicate that in this patient a beta-galactosidase A protein with altered charge and altered catalytic properties was present in relatively normal amounts, the first electrophoretic variant reported for a patient with a lysosomal hydrolase deficiency.
Competent Bacillus subtilis cultures synthesize a denatured DNA binding activity.
Authors: Eisenstadt E , Lange R , Willecke K
Published: May 2006

A protein activity has been detected in soluble extracts of competent cultures of bacillus subtilis which protects denatured DNA from nuclease solubilization. Both binding activity and competence development occur simultaneously but not coordinately, since the peak of binding activity appears 3 hr after the peak of competence. The binding activivity is not detected in physiologically noncompetent cultures, in an isogenic noncompetent cultures, in an isogenic noncompetent mutant grown through the competence regimen, or in early sporulating cells. The activity is included on Sephadex G-100 gel filtration columns but elutes in a broad nonhomogeneous peak. This binding activity may play a role in uptake of DNA and/or integration of exogenous DNA into the genome of competent B. subtilis cells.
Effect of a low-molecular-weight DNA binding protein, H1 factor, on the in vitro transcription of the lactose operon in Escherichia coli.
Authors: Crepin M , Cukier-Kahn R , Gros F
Published: May 2006

H1 protein, a heat-stable low-molecular-weight DNA-binding factor previously described by Cukier-Kahn et al. [Proc. Nat. Acad. Sci USA (1972) 69, 3643-3647] markedly stimulates in vitro synthesis of lac-specific RNA directed by bacteriophage lambdah80 dlac or phi80 dlac DNA templates in the presence of purified E. coli RNA polymerase holoenzyme. The extent of stimulation obtained by addition of H1 alone is usually greater than that observed with the cAMP receptor protein-cAMP combination. H1 effect varies quite appreciably (from 4- to 16-fold) with the functional state of the promoter, being much larger with lambdah80 dlac p-s, a transducing DNA carrying a superpromoter mutation, than with lambdah80 dlac p+. H1 and cAMP receptor protein effects are nearly additive, although interpretation of the data obtained at high H1 concentration is complicated by the appearance of some inhibitory property. While the cAMP-receptor-protein-mediated synthesis is asymmetrical ("I" strand almost exclusively copied), the degree of asymmetry observed with H1 is less pronounced, suggesting asymmetrical copying from the lac promoter and symmetric transcription from other regions of the DNA. Synthesis of lac-specific RNA from lambdah80 dtrp/lac or phi80 dlac p-r uv5 templates, in which lac promoters are insensitive to cAMP receptor protein, either as a result of lac fusion to the trp operon or mutation in the lac promoter, is totally H1-insensitive. Glycerol (10-15% w/w) can fully substitute for H1 in stimulating lac RNA synthesis in a fashion analogous to that reported for the cAMP receptor protein-cAMP system. The possibility that H1 acts by causing conformational modifications at the promoter level in a way that increases its functional state, and that this effect is more pronounced with operons sensitive to cAMP receptor protein, is discussed.
Spontaneous and induced mutagenesis in Western Equine encephalomyelitis virus in chick embryo cells with different repair activity.
Authors: Dubinin N P , Zasukhina G D , Nesmashnova V A , Lvova G N
Published: May 2006

Evidence was obtained indicating differences in the survival rate of Western equine encephalomyelitis virus after exposure to ultraviolet radiation and methyl methanesulfonate in commercial and leukosisfree chick embryo cells that differed in repair activity. The levels of spontaneous mutagenesis (on the basis of the yield of small palque variants of the encephalomyelitis virus) did not essentially change when the virus was passage in leukosis-free chick embryo cells, whereas an increase in the number of small palque variants was observed in the cells of commercial chick embryos. A 10-fold increase in the number of induced virus variants was observed in commercial chick embryo cells in experiments with methyl methanesulfonate as compared with the contorl, whereas the induction of virus variants was not noted in leukosis-free cells.