bluuebunny/crossref_metadata_2025 huggingface dataset:
Purification of a Specific tRNA by Sepharose-Bound Enzyme
Authors: Denburg Jeffrey , DeLuca Marlene
Published: May 2006

A new procedure for measuring binding of tRNA to aminoacyl-tRNA synthetases is described. The purified isoleucyl-tRNA synthetase from
Escherichia coli
can be covalently bound to activated Sepharose with retention of approximately 40% of the original enzymatic activity. If crude tRNA is passed through a small column of enzyme-Sepharose, isoleucyl-tRNA is preferentially retained. The procedure can be used as a means of purifying specific tRNA molecules.
Interferon: Evidence for Subunit Structure
Authors: Carter William A.
Published: May 2006

During the purification of mouse and human interferons, multiple active components have been detected. Mouse interferon was purified over 500-fold by differential precipitation, centrifugation, gel chromatography, and isoelectric focusing. On electrofocusing, two molecular forms (A and B) were noted. Form B (isoelectric point 7.35) had a molecular weight of about 38,000 and Form A (isoelectric point 7.15), which was equally active, a molecular weight of 19,000. Purified Form B was dissociable into Form A, but the reverse reaction occurred to a much lesser extent. Human interferon, purified about 1550-fold, is also composed of multiple molecular forms. Form B (pI 5.60) had a molecular weight of about 24,000 and Form A (pI 5.35), which may contain up to 85% of the total activity, a molecular weight of 12,000. Both forms appear to be equally active. The dissociation of both human and mouse interferons into subunits appears to take place during dialysis versus low salt (0.01 M Tris pH 7.4). The data are consistent with the idea that the native molecule exists as a dimer of similar or identical subunits. Dimer formation, which probably occurs within the cells, does not seem to lead to a measurable cooperative effect between the subunits.
Enzymatic Block in the Synthesis of Gangliosides in DNA Virus-Transformed Tumorigenic Mouse Cell Lines
Authors: Cumar Federico A. , Brady Roscoe O. , Kolodny Edwin H. , McFarland Vivian W. , Mora Peter T.
Published: May 2006

The ganglioside pattern of both SV40- and polyoma virus-transformed mouse cell lines differs from that of the parent cell lines or of cell lines that have transformed spontaneously in tissue culture. This is manifested by a dramatic decrease of gangliosides with an oligosaccharide chain larger than sialyllactose. Present investigations indicate that this change probably cannot be attributed to excessive catabolism of gangliosides, but is caused by impaired synthesis of tri- and tetrahexosyl gangliosides in the virus-transformed cell lines. We present evidence for the block of a required step for the biosynthesis of these ganglioside homologs. The block involves the enzyme catalyzing the transfer of
N
-acetylgalactosamine from uridine diphosphate
N
-acetylgalactosamine to hematosides (
N
-glycolylneuraminyl or
N
-acetylneuraminylgalactosylglucosyl ceramide). This well-defined enzymatic change opens the way for studies of the biochemical mechanism of the alteration of cell membranes which occurs after transformation by the tumorigenic DNA viruses polyoma and SV40.
Total Suppression of Pregnancy in Mice by Post-Coital Administration of Neuraminidase
Authors: Gasic Gabriel J. , Gasic Tatiana B.
Published: May 2006

Because of certain analogies between the spread of tumors and different steps of pregnancy culminating in egg implantation and invasive growth, pregnant mice were treated at different intervals
post coitum
with two thrombocytopenic agents which can reduce metastases by interfering with vascular lodgement and growth of tumor cells. It was found that both neuraminidase and antiplatelet serum were active against pregnancy, the enzyme being by far the more effective of the two. The mechanism of this effect involves both egg implantation and egg development. The effect cannot be explained solely by the thrombocytopenia produced by both agents.
Wiskott-Aldrich Syndrome, A Genetically Determined Cellular Immunologic Deficiency: Clinical and Laboratory Responses to Therapy with Transfer Factor
Authors: Levin A. S. , Spitler L. E. , Stites D. P. , Fudenberg H. H.
Published: May 2006

Patients with diseases associated with defects in cellular immunity, such as the Wiskott-Aldrich syndrome, characteristically have severe recurrent infections and usually succumb to overwhelming infection at an early age.

This communication describes a patient with this syndrome, defective delayed hypersensitivity by skin tests and by
in vitro
lymphocyte response, who was treated with dialysate of peripheral blood leukocytes (transfer factor). After treatment, the clinical status of the patient improved dramatically, concomitant with the development of delayed hypersensitivity to antigens to which the donor was sensitive.
In vitro
tests after transfer indicated that the patient's lymphocytes, when stimulated by specific antigen, produced migration inhibitory factor without concomitant DNA synthesis. These observations dissociate skin test sensitivity and activity of migration inhibitory factor from
in vitro
blastogenesis. Further, the response to phytohemagglutinin remained diminished before and after therapy. While these findings represent only an individual case, the climical results suggest that investigation of the use of transfer factor appears warranted in the therapy of Wiskott-Aldrich syndrome and other genetically-determined diseases associated with impaired cellular immunity.
Elevated Concentration of Adenosine 3′:5′-Cyclic Monophosphate in Intestinal Mucosa after Treatment with Cholera Toxin
Authors: Schafer David E. , Lust W. David , Sircar Bithi , Goldberg Nelson D.
Published: May 2006

A heat-labile factor in cell-free filtrate of a
Vibrio cholerae
culture induces a marked rise in the wet-weight concentration of adenosine 3′:5′-cyclic monophosphate (cyclic AMP) in the intestinal mucosa of the dog. The increase becomes appreciable 1-1.5 hr after intraluminal administration of the filtrate, about the same time as the onset of intestinal secretion in response to a heat-labile enterotoxin in the filtrate. These results are consistent with the hypothesis that cyclic AMP may be an intermediary in the intestinal secretory response to cholera toxin.
Chloride and Potassium Activities in Luminal Fluid of Turtle Thyroid Follicles as Determined by Selective Ion-Exchanger Microelectrodes
Authors: Chow S. Y. , Kunze D. , Brown A. M. , Woodbury D. M.
Published: May 2006

Cl
-
and K
+
activities in the follicular lumen and the intraluminal potential of the same lumen were measured simultaneously with specific liquid ion-exchanger and 3 M KCl microelectrodes, respectively, in turtle thyroid glands. The Cl
-
equilibrium potential between the thyroid interstitium and the lumen calculated from the measured Cl
-
activities was higher than the directly measured intraluminal potential. These data indicate that Cl
-
is actively transported out of the follicular lumen in turtle thyroid gland. On the other hand, the calculated K
+
equilibrium potential was not different from the directly measured potential, which indicates that K
+
is probably distributed passively according to the electrochemical gradients between the interstitial and the luminal compartments in turtle thyroid gland. Results obtained from the specific liquid ion-exchanger microelectrode studies correlate well with those obtained from previous radioautographic observations and chemical determinations.
Surface Charge and the Conductance of Phospholipid Membranes
Authors: McLaughlin S. G. A. , Szabo G. , Eisenman G. , Ciani S. M.
Published: May 2006

Bilayer membranes, formed from various phospholipids, were studied to assess the influence of the charge of the polar head groups on the membrane conductance mediated by neutral „carriers” of cations and anions. The surface charge of an amphoteric lipid, phosphatidyl ethanolamine, was altered by varying the pH, and the surface charge of several lipids was screened by increasing the ionic strength of the solution with impermeant monovalent and divalent electrolytes. The surface charge should be a key parameter in defining the membrane conductance for a variety of permeation mechanisms; conductance measurements in the presence of carriers may be used to estimate the potential difference, due to surface charge, between the interior of the bilayer and the bulk aqueous phase. The large changes in conductance observed upon varying the surface charge density and the ionic strength agree with those predicted by the Gouy-Chapman theory for an aqueous diffuse double layer. Explicit expressions for the dependence of the membrane conductance on the concentrations of the carrier, the permeant ion, the surface charge density, and the ionic strength are presented.
Nuclear Magnetic Resonance Spectroscopy. Variable-Temperature
13
C and
19
F Study of the Chair-Chair Interconversion of 1,1,3,3-Tetramethylcyclohexane and
gem
-Difluoro-1,1,3,3-Tetramethylcyclohexanes
Authors: Doddrell David , Charrier Claude , Hawkins Bruce L. , Crain W. O. , Harris Leland , Roberts John D.
Published: May 2006

A variable-temperature, proton noise-decoupled,
13
C nmr spectral study of the chair-chair interconversion in 1,1,3,3-tetramethylcyclohexane has demonstrated the utility of
13
C spectra for probing conformational equilibria. There is a much larger chemical-shift difference between the carbons of axial and equatorial methyl groups than between the protons of these methyl groups, 133 Hz compared to 7.5 Hz. Comparison of the activation parameters determined from the
13
C spectra of 1,1,3,3-tetramethylcyclohexane with those determined from a variable-temperature
19
F study on 2,2,6,6-tetramethyl-1,1-difluorocyclohexane shows that the introduction of a
gem
-difluoro group into the ring causes significant steric interactions. The
13
C chemical shifts for 1,1,3,3-tetramethylcyclohexane reflect the importance of the methyl-methyl 1,3-diaxial interactions.
Affinity Labeling of the Heavy and Light Chains of a Myeloma Protein with Anti-2,4-Dinitrophenyl Activity
Authors: Haimovich Joseph , Givol David , Eisen Herman N.
Published: May 2006

A mouse myeloma protein with high affinity for 2,4-dinitrophenyl (Dnp) ligands was reacted with the bromoacetyl derivatives of
N
-Dnp-ethylenediamine and
ε
-
N
-Dnp-L-lysine. Up to 1.4 sites per protein molecule were covalently labeled. The labeling reactions were essentially completely blocked by a large excess of Dnp ligands that do not combine covalently (e.g.,
ε
-Dnp-L-lysine). Analyses of the labeled protein revealed that the bromoacetyl derivative of
N
-Dnp-ethylenediamine reacted exclusively with tyrosyl in the light chain, while the derivative of
ε
-Dnp-L-lysine reacted exclusively with lysyl in the heavy chain. The findings support the conclusion that chains are involved in forming specific combining sites.
Amino Acid Incorporation by Isolated Rat Liver Mitochondria during Liver Regeneration
Authors: Malkin Leonard I.
Published: May 2006

Intact mitochondria, isolated from regenerating rat liver 2-3 days after partial hepatectomy, are 2.5-3 times more active in amino acid incorporation than mitochondria from control livers. Liver mitochondria from sham-operated animals showed normal amounts of incorporation. Sterile procedures insured low levels of bacterial contamination; cycloheximide was used to eliminate any contribution by contaminating microsomes. Mitochondria from control and 3-day-old regenerating livers were nearly identical in their concentration of several respiratory chain components, P/O ratios, specific O
2
consumption, and cytochrome
c
oxidase activities. Small differences were observed in respiratory control ratios but these were shown to be unrelated to the differences observed in amino acid incorporating ability. Differential contamination by lysosomes and differences in lysosome fragility were also shown not to be factors in the increased incorporation by regenerating liver mitochondria. Thus, mitochondria from rapidly growing and dividing mammalian tissues are more active in protein synthesis than mitochondria from tissues that grow and divide more slowly.
Bovine Parathyroid Hormone: Amino Acid Sequence
Authors: Brewer H. Bryan , Ronan Rosemary
Published: May 2006

Bovine parathyroid hormone has been isolated in homogeneous form, and its complete amino acid sequence determined. The bovine hormone is a single chain, 84 amino acids long. It contains amino-terminal alanine, and carboxyl-terminal glutamine. The bovine parathyroid hormone is approximately three times the length of the newly discovered hormone, thyrocalcitonin, whose action is reciprocal to parathyroid hormone.
The Rolling Circle for ϕX DNA Replication, II. Synthesis of Single-Stranded Circles
Authors: Dressler David
Published: May 2006

ϕX-infected cells have been allowed to incorporate tritiated thymidine late in the phage life cycle when single-stranded circles are the product of DNA synthesis. Virtually all of the radioactivity is recovered in a continuum of actively replicating viral DNA molecules. These molecules are termed rolling circle intermediates because they are characterized by three structural properties. They possess positive strands that are longer than the length of a mature viral genome, and negative strands that are covalently closed single-stranded circles. The 3′ termini of the long positive strands lie upon the template rings, while the 5′ ends are free in solution.

From these experimental data, the basic mode of synthesis is deduced to involve the continuous elongation of the open positive strand by endless copying around the circular negative strand template. As new bases are added to the template-bound (3′) end of the positive strand, the distal (5′) end is displaced from the template ring as a single-stranded tail of increasing length. It is the tail which serves as the source of material for progeny chromosomes.

These data confirm our characterization of this ϕX intermediate, which initially was based only on the possession of long positive strands, and extend this characterization to include experimental statements about the circular nature of the template DNA strand, and the 5′ to 3′ direction of polynucleotide chain growth within the intermediate. Moreover, the description can now be applied to all of the molecules which acquire label during a pulse.
Radiation Sensitivity of New Zealand Black Mice and the Development of Autoimmune Disease and Neoplasia
Authors: Morton Jane I. , Siegel Benjamin V.
Published: May 2006

Young New Zealand Black (NZB) mice manifested extremely high resistance to the lethal effects of acute exposures to ionizing radiation, with a dose necessary to kill 50% of the animals within 30 days, LD
50(30)
, of 964 roentgens (R) at 30 days of age and of 856 R for 90-day-old mice. In contrast, Coombs' positive 9-month-old NZB mice (with low primary immune response) were highly susceptible (LD
50(30)
= 543 R), possibly because of anemia-stimulated erythropoiesis leading to a depletion of stem cells. The radiation resistance of young NZB mice, combined with previous observations of their immunologic hyper-responsiveness, support the concept that NZB mice possess an unusually large pool of hematopoietic stem cells, an abnormality which may predispose them to the development of autoimmune disease and neoplasia.
Nuclear Involvement Poin xvirus Infection
Authors: Walen Kirsten H.
Published: May 2006

During the first hours of infection with vaccinia virus, part of the chromosomal DNA of host cells is degraded, part of it is released from the cell, and part of it eventually appears in cytoplasmic foci associated with the reproduction of virus. The DNA of the infecting particle is first found attached to the chromosomes. Intranuclear foci of DNA incorporation appear later; these rapidly move out into the perinuclear space and eventually become typical cytoplasmic “virus factories.” Each of these observations points to a more direct involvement of the nucleus in viral infection than was previously envisaged.
The Molecular Defect in a Protein (CRA) Found in γ1 Heavy Chain Disease, and Its Genetic Implications
Authors: Franklin E. C. , Frangione B.
Published: May 2006

A γ1 protein, designated CRA, found in heavy chain disease contains three inter-heavy disulfide bridges instead of the two normally found in γ1 immunoglobulin heavy chains. Almost the entire Fd fragment is missing. The NH
2
terminal region is heterogeneous and contains carbohydrate; after 11 residues that do not resemble any of the known heavy-chain variable-region subclasses, normal synthesis seems to be resumed at the same amino acid residue as in another heavy-chain disease protein (ZUC). This finding raises the possibility that glutamic acid at position 216 represents the beginning of the Fe region, synthesized under the direction of another gene.
Proton Magnetic Resonance Studies of the Ferredoxins from Spinach and Parsley
Authors: Poe M. , Phillips W. D. , Glickson J. D. , McDonald C. C. , Pietro A. San
Published: May 2006

Contact-shifted resonances have been detected in the pmr spectra of both oxidized and reduced forms of spinach and parsley ferredoxins. These resonances are assigned to the β-CH
2
protons of four cysteine residues that are thought to bind the iron-sulfur redox center to the polypeptide chain. Temperature dependences of contact shifts reveal that the two iron atoms are antiferromagnetically coupled in both redox forms of each of these proteins. Thermal population of magnetic states gives rise to the contact shifts observed in the formally diamagnetic oxidized forms of these ferredoxins and accounts for the failure of contact shifts in the reduced forms exhibit to a Curie Law temperature dependence. It appears that the unpaired electron of reduced spinach and parsley ferredoxin is unequally distributed over the two iron centers. Valence states for the iron pairs of high-spin Fe
+3
-Fe
+3
and Fe
+2
-Fe
+3
for the oxidized and reduced forms, respectively, are compatible with the nmr results.
Deficiency of Coenzyme Q
10
in Gingival Tissue from Patients with Periodontal Disease
Authors: Littarru Gian Paolo , Nakamura Ryo , Ho Lester , Folkers Karl , Kuzell William C.
Published: May 2006

The specific activities of the succinate dehydrogenase-coenzyme Q
10
reductase in gingival tissue from patients with periodontal disease have been compared with the corresponding specific activities of normal human periodontal tissue. The gingival biopsies from patients having diseased periodontal tissue showed a deficiency of coenzyme Q
10
, in contrast to those of the normal periodontal tissue which showed no deficiency. The presence or absence of a deficiency of coenzyme Q
10
in the succinate-coenzyme Q
10
enzyme system is appraised by determining the specific activity in the absence and again in the presence of exogenous coenzyme Q
3
. An increase in specific activity of this mitochondrial enzyme system in the presence of exogenous coenzyme Q
3
reflects the mitochondrial deficiency of coenzyme Q
10
. Such increases ranged from 38-120% and averaged 81% for the individuals with periodontal disease, and were highly significant statistically.

These data correlate with clinical studies in Japan that have indicated a therapeutic benefit of the administration of coenzyme Q
7
to many patients with severe and destructive periodontal disease and with the benefit of administration of hexahydrocoenzyme Q
4
to one such patient in the current work.
Immunocytochemical Localization of Phytochrome
Authors: Pratt Lee H. , Coleman Richard A.
Published: May 2006

An immunocytochemical assay, which localizes phytochrome
in situ
, indicates that this plant chromoprotein is associated with both nuclei and plastids, in addition to the cytoplasm. In an etiolated oat shoot, phytochrome is most abundant just behind the apex of the coleoptile, where it is associated with parenchyma cells; it is apparently absent at the extreme apx of the coleoptile. Further back from the tip, phytochrome is found in the epidermal cells of the coleoptile; it decreases in concentration toward the node, where it is again abundant. Phytochrome is also abundant in the extreme apical cells of young adventitious roots and in association with the procambium of the mesocotyl.
Expression of Tyrosine Aminotransferase Activity in Somatic-Cell Heterokaryons: Evidence for Negative Control of Enzyme Expression
Authors: Thompson E. Brad , Gelehrter T. D.
Published: May 2006

Cells of the tyrosine aminotransferase (EC 2.6.1.5)-inducible line, HTC, were fused with those of the BRL-62 line, which contain little or no enzyme and are unresponsive to the usual steroid inducers. Histochemical examination of the resulting heterokaryons within 24 hr of the fusion showed them to have little or no enzyme and to be unresponsive to steroids. These experiments disclose that the observed negative dominance is universal in the fused cells and that such dominance occurs promptly after fusion, when loss of chromosomes has not occurred.
Appearance of T-cell Markers in Bone Marrow Rosette-Forming Cells after Incubation with Thymosin, a Thymic Hormone
Authors: Bach Jean-Francois , Dardenne Mireille , Goldstein Allan L. , Guha Arabinda , White Abraham
Published: May 2006

After incubation with thymosin, a thymic hormone, normal bone marrow rosette-forming cells acquire T-cell characteristics, including increased sensitivity to azathioprine, anti-lymphocyte serum, and anti-theta serum. This activity of thymosin provides a new sensitive and reproducible bioassay for thymosin, and is well correlated with an
in vivo
graft-versus-host assay. In addition, incubation of spleen cells from adult thymectomized mice with thymosin
in vitro
restores to normal their diminished sensitivity to azathioprine and anti-lymphocte serum.
Addition of Polyadenylate Sequences to Virus-Specific RNA during Adenovirus Replication
Authors: Philipson L. , Wall R. , Glickman G. , Darnell J. E.
Published: May 2006

Adenovirus-specific nuclear and polysomal RNA, both early and late in the infectious cycle, contain a covalently linked region of polyadenylic acid 150-250 nucleotides long. A large proportion of the adenovirus-specific messenger RNA contains poly(A). As revealed by hybridization experiments, the poly(A) is not transcribed from adenovirus DNA. Furthermore, an adenosine analogue, cordycepin, blocks the synthesis of poly(A) and also inhibits the accumulation of adenovirus messenger RNA on polysomes. Addition of poly(A) to viral RNA may involve a host-controlled mechanism that regulates the processing and transport of messenger RNA.
The Cortex of
Xenopus laevis
Embryos: Regional Differences in Composition and Biological Activity
Authors: Tomkins Robert , Rodman William P.
Published: May 2006

The cortex of fertilized
Xenopus laevis
eggs undergoes regional changes in its composition and morphogenetic activity during the first three divisions. Gray crescent and animal pole cortex of stage 1 (1-cell) and stage 4 (8-cell) embryos each contain a characteristic array of proteins. Implantation of pieces of cortex into the blastocoel of midblastula embryos was used to assay their inductive capacity. The gray crescent cortex was shown to be the only region that had significant axis-inducing activity. This activity increased from stage 1 to stage 4.
In Vitro Excision-Repair of Ultraviolet-Irradiated Transforming DNA from Bacillus subtilis
Authors: Heijneker H. L. , Pannekoek H. , Oosterbaan R. A. , Pouwels P. H. , Bron S. , Arwert F. , Venema G.
Published: May 2006

The biological activity of UV-inactivated
Bacillus subtilis
DNA is partly restored after incubation with a UV-specific endonuclease from
Micrococcus lutens
in conjunction with DNA polymerase and DNA ligase, both isolated from
Escherichia coli
. The restored activity is not further increased by photoreactivation. Pyrimidine dimers are specifically liberated when irradiated DNA is exposed to the three enzymes. None of these effects is observed when pancreatic DNase is used instead of UV-specific endonuclease.
Ribosome Formation is Blocked by Camptothecin, a Reversible Inhibitor of RNA Synthesis
Authors: Wu Roy S. , Kumar Ajit , Warner Jonathan R.
Published: May 2006

A new drug, camptothecin, has been used to study the regulation of ribosome synthesis in HeLa cells. 5 μM camptothecin inhibits the synthesis of heterogeneously sedimenting nuclear RNA by about 70%. Camptothecin also blocks a specific step in the processing of ribosomal precursor RNA, allowing the conversion of 45S RNA to 32S RNA, but inhibiting the conversion of 32S RNA to 28S RNA. The action of camptothecin, unlike that of actinomycin D, is rapidly reversible. Within 5 min after the removal of the drug, ribosomal precursor RNA synthesis and maturation resume at the normal rate.

Ribosomal proteins made in the presence of camptothecin do not accumulate in the nucleolus, and are not subsequently used to form ribosomes if RNA synthesis is allowed to resume.
Expression of Differentiated Functions in Hepatoma Cell Hybrids: Reappearance of Tyrosine Aminotransferase Inducibility after the Loss of Chromosomes
Authors: Weiss Mary C. , Chaplain Michèle
Published: May 2006

Hybrids from a cross of rat hepatoma cells with diploid epithelial cells from rat liver have been studied with respect to karyotype and expression of two functions limited to the hepatoma parent: high level of the enzyme tyrosine aminotransferase (EC 2.6.1.5; L-tyrosine:2-oxoglutarate aminotransferase) and its inducibility with steroid hormones. The hybrids that contain the complete chromosomal complements from both parents show low enzyme activity and no inducibility. One hybrid clone, and all of its derivatives, which have lost 30-40% of the chromosomes initially present, show enzyme inducibility. Induction of tyrosine aminotransferase in the hepatoma and hybrid cells responds similarly to inhibition by cycloheximide and actinomycin D, and to steroid concentration. The enzymes from induced and noninduced hepatoma cells and from induced hybrid cells are similar in heat sensitivity and intracellular distribution; those from noninduced hybrid and diploid rat epithelial cells are different.
Three Closely Linked Genetic Systems Relevant to Transplantation
Authors: Yunis E. J. , Amos D. B.
Published: May 2006

The concept that antigens of a major histocompatibility locus (
HL-A
), the mixed leukocyte reaction, and the rejection of a graft are expressions of the same genetic region has been generally accepted.

We have presented experiments that challenge the above concept and suggest that the rejection time of skin and organ transplants is dependent on immunization against the products of two, and possibly three, separate, but closely linked, genetic systems:
HL-A
, mixed leukocyte reaction (
MLR-S
), and hypersensitivity delayed reaction (
HDR
).

The findings presented and discussed here suggest that the HL-A antigens are not the primary factors involved in the cell-mediated component of allotransplantation, and that these antigens and phenotypes of the mixed leukocyte reaction can only be used as a guide in predicting the survival of allografts that are obtained from unrelated donors.
Immunoglobulin G and Free Kappa-Chain Synthesis in Different Clones of a Hybrid Cell Line
Authors: Mohit Behzad
Published: May 2006

13 clonal cell lines were isolated from a hybrid cell population established by cell fusion between cloned BALB/c myeloma cells that were resistant to 8-azaguanine and produced immunoglobulin G and free kappa chain and C
67
BL/6n lymphoma cells that were resistant to bromodeoxyuridine and did not produce immunoglobulins. Some of the histocompatibility-2 antigens of both parental cell lines could be demonstrated on all of the hybrid clones. 11 clones synthesized only free kappa chain. Two clones synthesized IgG of BALB/c type, as well as free kappa chain. These clones had higher chromosome number than did the clones that synthesized only kappa chains.
Nuclear Magnetic Resonance Studies of Lysine-Vasopressin: Structural Constraints
Authors: Von Dreele P. H. , Brewster A. I. , Bovey F. A. , Scheraga H. A. , Ferger M. F. , Du Vigneaud V.
Published: May 2006

The 220-MHz proton NMR spectra of lysine-vasopressin and some related compounds are examined in deuterated dimethyl sulfoxide to obtain structural information that must be satisfied by any proposed conformation of the molecule. This structural information is in the form of dihedral angles (for rotation about the NH-C
α
H bonds) from coupling constants, possible hydrogen bonding of the CONH
2
and backbone amide groups from the temperature-dependence of the chemical shift, and aromatic ring-aromatic ring interaction from the effect of the magnetically anisotropic groups on the chemical shift.
Autoimmune-Like Antibodies to the Ligand-Binding Sites of Myeloma Proteins
Authors: Sirisinha Stitaya , Eisen Herman N.
Published: May 2006

BALB/c mice were immunized with three A-myeloma proteins of BALB/c-2 or BALB/c origin (produced by plasmacytomas MOPC-315, MOPC-460, Adj. PC-22A). Noncross reacting antibodies were formed against Proteins-315 and 460, but the response to Protein-22A was marginal. Proteins-315 and 460 have anti-dinitrophenyl activity, and their reactions with the corresponding BALB/c antibodies were inhibited by dinitrophenyl ligands. It appears that antibodies can be formed in BALB/c mice against unique “idiotypic” determinants in the ligand-binding sites of some BALB/c mycloma proteins.
A Structure of Pyridine Nucleotides in Solution
Authors: Oppenheimer Norman J. , Arnold Lyle J. , Kaplan Nathan O.
Published: May 2006

Re-examination of the structure of pyridine coenzymes in solution by use of the 220-MHz high-frequency nuclear magnetic resonance spectrometer indicates that there is primarily one folded structure that is in rapid equilibrium with an open form. Reduced DPN
+
and reduced analogs of DPN
+
exist predominantly with the B side of the dihydropyridine ring folded against the adenine moiety. (The oxidized coenzymes appear to exist in the same folded structure.) Furthermore, the ribose protons undergo very little conformational change upon reduction of the pyridine ring; this observation strongly suggests a considerable similarity between the folded forms of the oxidized and reduced coenzymes. A model of the folded structure is presented.
Pyrolysis of Organomercury Compounds: Investigation by the Method of Matrix Isolation
Authors: Maltsev A. K. , Mikaelian R. G. , Nefedov O. M. , Hauge R. H. , Margrave J. L.
Published: May 2006

The method of matrix isolation has been used to investigate mechanisms of gas-phase chemical reactions, in particular the pyrolysis of some organomercury compounds. A molecular beam of pyrolysis products was condensed simultaneously with a large excess of rare gas at temperatures from 5 to 15°K to form a matrix that was subsequently studied by infrared spectroscopy. In the case of C
6
H
5
HgCCl
3
, we found that pyrolysis in the temperature range 220-400°C produced mainly dichlorocarbene. In addition, some trichloromethyl radical was observed and increased in relative importance at increased temperatures. Another identified product of pyrolysis was C
6
H
5
HgCl. In general, the same reactive intermediates, CCl
2
and CCl
3
, were found from pyrolysis of Hg(CCl
3
)
2
in the temperature range 250-500°C, along with CCl
3
HgCl and HgCl
2
. The identity of CCl
2
and CCl
2
was demonstrated by measurement of the relative intensities and isotopic splittings of stretching vibrations due to the chlorine isotopes. Isotopic patterns found for CCl
2
are:
v
3
(745.8, 744.0, 741.8 cm
-1
),
v
1
(719.5, 717.0, 714.9 cm
-1
) and for CCl
3
are:
v
3
(897.8, 896.4, 895.2, 893.9 cm
-1
). Less dilution with the rare gas or warming of the matrix produced a decrease of CCl
2
and CCl
3
spectral bands and an increase of bands due to C
2
Cl
4
, C
2
Cl
6
, and other products. These results show the usefulness of matrix isolation in the study of such reactive species as CCl
2
produced by pyrolysis in the gas phase.
The Comparative Specificity of Acid Proteinases
Authors: Voynick Irene M. , Fruton Joseph S.
Published: May 2006

Examination of the kinetic parameters for the hydrolysis, by acid proteinases, of a single peptide bond (between
p
-nitro-L-phenylalanyl and L-phenylalanyl) in a series of oligopeptides has shown that secondary interactions are important factors in determining the catalytic efficiency. Comparison of the action of highly purified pepsinlike enzymes (
Rhizopus
proteinase,
Mucor
proteinase, rennin) with that of swine pepsin A indicates significant differences among them, either in the binding of the substrate (as estimated by

K
m

), or in the catalytic efficiency (as measured by
k
cat
), or both. It may be concluded from these data that, in their action on oligopeptide substrates, the specificity of proteinases operating by a similar catalytic mechanism cannot be explained solely in terms of the amino acid residues flanking the sensitive peptide bond; in addition, the specificity includes significant contributions from secondary interactions arising from complementary relations between parts of the substrate and of the enzyme at a distance from the catalytic site. Data are also presented for the effect of urea (about 1 M) on the kinetic parameters of several acid proteinases; under the conditions of these studies, the binding of the substrate is affected to a much lesser degree than is the catalytic efficiency.
Isolation and Properties of Polypeptide Chain Initiation Factor FII from
Escherichia coli:
Evidence for a Dual Function
Authors: Dubnoff Jerry S. , Maitra Umadas
Published: May 2006

Initiation factor FII (F
3
, factor B) has been purified from
Escherichia coli
Q13 to apparent homogeneity. It is a heat-stable basic protein, consisting of a single polypeptide chain of molecular weight 21,000. FII is required, in addition to the other factors FI and FIII, for the formation of a 70S complex containing fMet-tRNA, poly(U,G) (used as a model messenger RNA), and the ribosome. FII also is capable of dissociating 70S ribosomes to 30S and 50S subunits. Evidence is presented that both activities are mediated by the same protein.
Restoration of Several Morphological Characteristics of Normal Fibroblasts in Sarcoma Cells Treated with Adenosine-3′:5′-Cyclic Monophosphate and Its Derivatives
Authors: Johnson George S. , Friedman Robert M. , Pastan Ira
Published: May 2006

Sarcoma cells growing in tissue culture have morphological and growth characteristics different than normal fibroblasts. Several of the morphological characteristics of normal fibroblasts are regained when the cells are incubated with dibutyryl-cyclic AMP or butyryl-cyclic AMP (0.1-1 mM), or cyclic AMP (3 mM) plus theophylline (1 mM), but not with ATP, ADP, AMP, adenine, or adenosine (1-7 mM). The cell bodies become elongated; distinct narrow processes are formed. With prolonged incubation, the cells show less tendency to pile up or become polygonal. Further, L-929 and Rous sarcomatransformed hamster cells orient in parallel arrays characteristic of contact inhibition. The cells retain their altered morphology as long as the butyryl-cyclic AMP is present, but revert after its removal. Experiments with cycloheximide, puromycin, and actinomycin D indicate that protein Synthesis, but not RNA synthesis, is required for the response. Microtubular proteins may be involved. No response is observed with normal fibroblasts or with various epithelial cells. The data suggest that cyclic AMP may be an important factor in the determination of morphology of normal fibroblasts and this function may be lost or altered during transformation.
Transformation of Rat and Hamster Embryo Cells by Extracts of City Smog
Authors: Freeman Aaron E. , Price Paul J. , Bryan Robert J. , Gordon Robert J. , Gilden Raymond V. , Kelloff Gary J. , Huebner Robert J.
Published: May 2006

Extracts of particulate matter from condensates of city air were tested for their ability to transform rat or hamster cell cultures. Uninfected rat embryo cultures were not transformed, but cultures chronically infected with Rauscher leukemia virus were transformed by benzpyrene or by extracts of city smog. The smog extracts were 600 times more active than pure benzpyrene as transforming agents. Hamster embryo cultures infected with hamster leukemia virus were equally as sensitive as leukemia-infected rat cultures to the transforming effects of smog; uninfected hamster cultures were also transformed, although tenfold higher doses of smog extract were required.
Enhanced Immunogenicity of Chemically-Coated Syngeneic Tumor Cells
Authors: Martin William J. , Wunderlich John R. , Fletcher Freeman , Inman John K.
Published: May 2006

The immunogenicity of the EL-4 strain of mouse lymphoid leukemia cells in syngeneic C57BL/6 recipients was enhanced by
in vitro
coating of the cells with either Concanavalin A or dinitrophenylaminocaproate. The tumor-specific immune response was quantitated using a recently developed assay that involves
in vitro
cell-mediated cytotoxicity.
Absence of Adaptive Modification in Developing Retinotectal Connections in Frogs after Visual Deprivation or Disparate Stimulation of the Eyes
Authors: Jacobson Marcus
Published: May 2006

Action potentials evoked in the tectum by visual stimulation of the ipsilateral eye were absent in frog larvae and developed during metamorphosis. Formation of the connections underlying these responses is not based on the animal's visual experience. The development of the ipsilateral retinotectal projection occurred normally in frogs reared through metamorphosis in the dark from midlarval stages to adults. Inversion of one eye of frog larvae did not affect the development of ipsilateral retinotectal projections, which developed according to the inherent correspondences between the retinae regardless of the disparities produced by changing the relative positions of the eyes. No compensatory changes occurred in the retinotectal projections in response to the surgical derangement.

Skin grafts completely occluding one eye, which were made at early larval stages and left in place for up to 88 days, did not affect the development of normal ipsilateral retinotectal connections. However, abnormal ipsilateral tectal responses evoked by stimulation through either the normal eye or the occluded eye were found in adult frogs after occlusion of one eye from larval stages for more than 121 days. It was concluded that visual stimulation is not required for the normal development of ipsilateral retinotectal connections but is required for their long-term maintenance.
Use of Monkey-Mouse Hybrid Cells for the Study of the Cellular Regulation of Interferon Production and Action
Authors: Cassingena R. , Chany C. , Vignal M. , Suarez H. , Estrade S. , Lazar P.
Published: May 2006

Four clones of a somatic monkey-mouse hybrid cell line were studied. One of these clones produced both mouse and monkey interferon, while the three others produced only mouse interferon. All four were, however, sensitive to both mouse and monkey (or human) interferon. The karyotype analysis of these four hybrid clones and the parental cell lines enabled us to locate the possible genetic site governing the synthesis of monkey interferon on a small subtelocentric monkey chromosome. The genetic site responsible for the synthesis of the antiviral protein is located on a different (monkey or mouse) chromosome.
Inhibition of the Metabolism of 25-Hydroxycholecalciferol by Actinomycin D and Cycloheximide
Authors: Tanaka Y. , Deluca H. F.
Published: May 2006

Actinomycin D (or cycloheximide) administered prior to radioactive 25-hydroxycholecalciferol blocks the metabolism of 25-hydroxycholecalciferol to polar metabolites that accumulate in intestinal tissue, while it does not prevent the 25-hydroxylation of vitamin D
3
in the liver. Actinomycin D given after radioactive 25-hydroxycholecalciferol does not inhibit 25-hydroxycholecalciferol metabolism. These results indicate that 25-hydroxycholecalciferol must interact with the nuclei of cells to bring about the production of an enzyme(s) that converts it to its polar metabolites.
The Yeast Phenylalanyl-Transfer RNA Synthetase Recognition Site: The Region Adjacent to the Dihydrouridine Loop
Authors: Dudock B. , DiPeri C. , Scileppi K. , Reszelbach R.
Published: May 2006

Purified yeast phenylalanyl-tRNA synthetase can aminoacylate (yeast) tRNA
Phe
, (wheat) tRNA
Phe
, and (
Escherichia coli
) tRNA
1
Val
(1, 2). We now report that this synthetase can also aminoacylate (
E. coli
) tRNA
Phe
and (
E. coli
) tRNA
1
Ala
. Highly purified (
E. coli
) tRNA
Phe
is heterologously aminoacylated to approximately 90% of the extent achieved with the homologous enzyme (crude
E. coli
phenylalanyl-tRNA synthetase). Pure (
E. coli
) tRNA
1
Ala
(the major species) is heterologously aminoacylated to 70% of the extent achieved with the homologous synthetase (crude
E. coli
alanyl-tRNA synthetase).

(
E. coli
) tRNA
Phe
is the fourth purified transfer RNA of known sequence to be shown to be an acceptable substrate for purified yeast phenylalanyl-tRNA synthetase. A comparison of these sequences shows that only one region is extremely similar in all four tRNAs. This region is located adjacent to the dihydrouridine loop, and consists of the nucleotides [Formula: see text] We conclude that this is the synthetase recognition site for yeast phenylalanyl-tRNA synthetase.

This conclusion is further supported by partial fragment analysis of (
E. coli
) tRNA
1
Ala
.
ε-(γ-Glutamyl)lysine in Fibrin: Lack of Crosslink Formation in Factor XIII Deficiency
Authors: Pisano J. J. , Finlayson J. S. , Peyton Marjorie P. , Nagai Yumiko
Published: May 2006

Fibrin clots formed in normal plasma contained about 6 mol of ε-(γ-glutamyl)lysine per mol of fibrin, whereas those formed in plasma from individuals with Factor XIII deficiency contained little or none of this crosslink (0.02-0.64 mol/mol of fibrin). Partial supplementation of the plasma with Factor XIII, at a single concentration tested, commensurately increased the number of crosslinks.
Isolation of Transducing Particles of ϕ80 Bacteriophage That Carry Different Regions of the
Escherichia coli
Genome
Authors: Press R. , Glansdorff N. , Miner P. , Vries J. De , Kadner R. , Maas W. K.
Published: May 2006

It has been possible to mate two strains harboring F-prime (F′) factors and to isolate from such matings rare recombinants that behave as though the two episomes had fused. Thus, two genes not previously linked may be brought into close proximity.

An F′ factor carrying the attachment site for ϕ80 was fused with one carrying the
met-ppc-arg
region of the chromosome. Lysogenization of such a strain, followed by induction, led to the isolation of ϕ80
arg
+
and ϕ80
met
+
transducing phages. This technique may be utilized as a general method for joining diverse bacterial genes to the genome of phage ϕ80.
Nuclear Magnetic Resonance Spectrum of Lysine-Vasopressin and Its Structural Implications
Authors: Dreele P. H. Von , Brewster A. I. , Scheraga H. A. , Ferger M. F. , Vigneaud V. Du
Published: May 2006

The NMR spectra at 220 MHz of lysinevasopressin and its precursors were measured in dimethyl sulfoxide, and the peaks were assigned to specific protons. Information about hydrogen bonding was obtained from the temperature coefficients of the chemical shifts. With these data, and with several chemical-shift positions and coupling constants, structural information was derived for this polypeptide hormone.
A Form of Cytochrome
b
5
That Contains an Additional Hydrophobic Sequence of 40 Amino Acid Residues
Authors: Spatz Lawrence , Strittmatter Philipp
Published: May 2006

A species of cytochrome
b
5
with a monomer molecular weight of 16,700 has been isolated from rabbit-liver microsomes by a procedure that uses detergents and avoids the use of any proteolytic or lipolytic enzymes. This detergent-extracted cytochrome
b
5
is larger than the trypsin- or lipase-extracted enzyme, and appears to contain an extremely hydrophobic appendage of 40 amino acids, probably at the N-terminus. The hydrophobic character of the extra amino acid sequence leads to aggregation in the absence of detergents, and may be of considerable importance in the binding of the enzyme to microsomes. It is suggested that the hydrophilic portion of the cytochrome molecule, which bears the heme and is enzymatically functional, is oriented toward the surface of the membrane where it readily reacts with nonmicrosomal proteins, while the hydrophobic “tail” anchors the heme protein tightly to the membrane.
Interaction of Human Growth Hormone and Human Erythrocyte Membranes Studied by Intrinsic Fluorescence
Authors: Sonenberg Martin
Published: May 2006

The intrinsic fluorescence of human erythrocyte membranes excited by unpolarized and polarized light has been studied with and without the addition of human growth hormone. The peak emission intensity of the membranes appeared at 332 nm, with a distinct shoulder at about 303 nm. Excitation spectra contained two peaks, at 282 and 225 nm. Fluorescence polarization was maximal (about 0.4) near 295 nm and decreased to approximately 0.18 near 225 nm. In the presence of 1 × 10
-15
M human growth hormone, or 70 molecules per membrane (1.45 × 10
-6
cm
2
), there was about a 20% decrease in peak membrane fluorescence. This occurred maximally with excitation at 282 and 225 nm, with little difference with excitation at 295 nm. Human growth hormone also decreased the fluorescence polarization from 0.34 to 0.25. The growth hormone effect was optimal at 37°C and pH 7.4. No effect was noted at pH 6.0 or 8.0. Bovine growth hormone or bovine serum albumin was without effect. A biologically active fragment from a tryptic digest of bovine growth hormone produced effects on membrane fluorescence similar to human growth hormone.

The data are consistent with the proposition that human growth hormone, by some cooperative mechanism, produces a conformational change in the membrane proteins with associated depolarization of fluorescence.
Detection of Australia Antigen by Radioimmunoassay
Authors: Aach Richard D. , Grisham Joe W. , Parker Charles W.
Published: May 2006

A double-antibody radioimmunoassay has been developed for the detection of Australia antigen and antibodies to Australia antigen in human sera. The assay is simple to perform, and can be completed in 18 hr. Based on parallel studies of human sera, it is approximately 2000 times more sensitive than agar gel diffusion and 200 times more sensitive than quantitative complement fixation. Australia antigen or antibody to Australia antigen was demonstrated in 22 of 23 single serum samples obtained from patients acutely ill with the long-incubation form of hepatitis; eight of the sera were negative when evaluated by less sensitive techniques.
Antibody to the RNA-Dependent DNA Polymerase of Mammalian C-Type RNA Tumor Viruses
Authors: Aaronson Stuart A. , Parks Wade P. , Scolnick Edward M. , Todaro George J.
Published: May 2006

Sera from rats bearing transplantable tumors induced by murine C-type tumor viruses contain an inhibitor of the activity of the viral RNA-dependent DNA polymerase. The inhibitor is shown to be an immunoglobulin (IgG) directed against the enzyme. Antiserum made in rabbits against partially purified murine leukemia virus polymerase also inhibits the polymerases of other mammalian C-type RNA-containing tumor viruses. Thus, the polymerases from different mammalian tumor viruses are antigenically related.
Membrane-Associated DNA in the Cytoplasm of Diploid Human Lymphocytes
Authors: Lerner R. A. , Meinke W. , Goldstein D. A.
Published: May 2006

A species of DNA that is apparently associated with the plasma membrane of diploid human lymphocytes that are continously growing is described. This DNA differes from nuclear or mitochondrial DNA by virtue of its location in the cell, time of synthesis in the cell cycle, and various physical properties. At present, the role of this DNA is unknown.