bluuebunny/crossref_metadata_2025 huggingface dataset:
Transforming gene product of Rous sarcoma virus phosphorylates tyrosine
Authors: Hunter Tony , Sefton Bartholomew M.
Published: May 2006

The protein kinase activity associated with pp60

src

, the transforming protein of Rous sarcoma virus, was found to phosphorylate tyrosine when assayed in an immunoprecipitate. Despite the fact that a protein kinase with this activity has not been described before, several observations suggest that pp60

src

also phosphorylates tyrosine
in vivo
. First, chicken cells transformed by Rous sarcoma virus contain as much as 8-fold more phosphotyrosine than do uninfected cells. Second, phosphotyrosine is present in pp60

src

itself, at one of the two sites of phosphorylation. Third, phosphotyrosine is present in the 50,000-dalton phosphoprotein that coprecipitates with pp60

src

extracted from transformed chicken cells. We infer from these observations that pp60

src

is a novel protein kinase and that the modification of proteins via the phosphorylation of tyrosine is essential to the malignant transformation of cells by Rous sarcoma virus. pp60

sarc

, the closely related cellular homologue of viral pp60

src

, is present in all vertebrate cells. This normal cellular protein, obtained from both chicken and human cells, also phosphorylated tyrosine when assayed in an immunoprecipitate. This is additional evidence of the functional similarity of these structurally related proteins and demonstrates that all uninfected vertebrate cells contain at least one protein kinase that phosphorylates tyrosine.
Variability of the magnetic moment of carbon monoxide hemoglobin from carp.
Authors: Cerdonio M , Morante S , Vitale S , De Young A , Noble R W
Published: May 2006

Deionized carp carbon monoxide hemoglobin in distilled water or in bis(2-hydroxyethyl)imino-tris(hydroxymethyl)methane or Tris buffer exhibits a slight but significant paramagnetism. This is most clearly demonstrated by the decrease in this paramagnetism that is caused by the addition of inositol hexaphosphate to this protein in the former buffer at pH 6.3-6.4. No such effect is seen when inositol hexaphosphate is added to carp cyanomethemoglobin, demonstrating that the change observed with carbon monoxide derivative is not due to a modification in the diamagnetic properties of the protein.
The 68,000-dalton neurofilament-associated polypeptide is a component of nonneuronal cells and of skeletal myofibrils
Authors: Wang Chung , Asai David J. , Lazarides Elias
Published: May 2006

Purified preparations of 10-nm neurofilaments from rat spinal cord and bovine or porcine brain contain a predominant 68,000-dalton polypeptide. This polypeptide is also a major component of the neurofilaments that copurify with brain tubulin isolated by cycles of polymerization and depolymerization. A protein that has the same isoelectric point and molecular weight as the neurofilament-associated polypeptide has also been identified as a cytoskeletal protein in a variety of avian and mammalian cell types, including baby hamster kidney (BHK-21) mouse 3T3, Novikoff rat hepatoma, chicken fibroblast, and chicken muscle cells. This protein is also a component of isolated chicken skeletal myofibrils. One-dimensional peptide maps of the 68,000-dalton proteins purified by two-dimensional isoelectric focusing/NaDodSO
4
/polyacrylamide gel electrophoresis from myofibrils, cycled tubulin, purified neurofilaments, and various cultured cell types were identical. In immunofluorescence this protein was associated with cytoplasmic intermediate filaments and myofibril Z discs. These results indicate that the neurofilament-associated polypeptide is a conserved protein that is present in many different cell types in addition to neuronal cells. Because some of these cells contain the major components of two other intermediate filament classes, desmin and vimentin, a given cell type may contain the subunits of at least three distinct intermediate filament types.
Autosomal dominant aniridia: probable linkage to acid phosphatase-1 locus on chromosome 2.
Authors: Ferrell R E , Chakravarti A , Hittner H M , Riccardi V M
Published: May 2006

Maximum likelihood analysis for linkage between autosomal dominant aniridia and 12 biochemical and serological markers in a single large family showed a probable linkage between autosomal dominant aniridia and the enzyme acid phosphatase-1. The presence of an autosomal dominant aniridia gene linked to acid phosphatase-1 on chromosome arm 2p and the existence of an aniridia syndrome resulting from deletion of band 13 of the short arm of chromosome 11 establishes a chromosome basis for genetic heterogeneity of aniridia phenotypes.
Electrical excitability: a spectrum of properties in the progeny of a single embryonic neuroblast.
Authors: Goodman C S , Pearson K G , Spitzer N C
Published: May 2006

We have examined the range of some properties of the progeny of a single embryonic precursor cell in the grasshopper. The approximately 100 progeny of this single neuroblast share certain features such as their transmitter and some aspects of their morphology; at the same time, however, they demonstrate a broad spectrum of electrical properties, from spiking to non-spiking neurons. The first-born progeny are spiking neurons with peripheral axons. Many of the progeny, including all of the last-born, do not generate action potentials. The nonspiking progeny are local intraganglionic neurons and appear to compose a major proportion of the progeny of this neuroblast. All of the nonspiking neurons have calcium inward current channels and can make action potentials when outward current channels are blocked. We propose a model for grasshopper neurogenesis based on cell lineage such that (i) certain features (e.g., transmitter) are shared by the progeny of all cell divisions from a single neuroblast, and (ii) other features (e.g., electrical properties) are shared by the progeny of a given birth position (e.g., first versus last born) from all of the neuroblasts. According to this model, the first-born progeny from all neuroblasts are spiking neurons, whereas the last-born are nonspiking.
Physiological and morphological studies of rat pheochromocytoma cells (PC12) chemically fused and grown in culture.
Authors: O'Lague P H , Huttner S L
Published: May 2006

Cell fusion induced by polyethylene glycol has been used to produce in culture giant multinucleate PC12 cells (up to 300 micron in diameter compared to 10-20 micron for unfused cells). Fused cells, like their unfused counterparts, were found to express various neuronal properties. They contained catecholamines. In the presence of nerve growth factor they extended long processes and expressed Na+, Ca2+, and K+ conductances generally associated with excitable cells. In the absence of nerve growth factor these cells neither grew long processes nor generated Na+-spikes. Other neuronal properties were also observed.
Structure-sensitive resonance Raman bands of capped tetraphenylporphyrinatoiron complexes
Authors: Linard Jack E. , Shriver Duward F. , Basolo Fred
Published: May 2006

Resonance Raman spectra have been determined for the capped tetraphenylporphyrinatoiron complexes and their base adducts. The five-coordinate mono-base complexes of these porphyrin complexes display Raman spectra that are nearly identical to those previously determined for five-coordinate iron(II) tetraphenylporphyrin complexes in the marker regions around 1540, 1345, and 370 cm
-1
. A similar correspondence is found between Raman bands of iron(II) complexes of the capped complexes and those of tetraphenylporphyrin. By contrast, the unusual pseudo-six-coordinate iron(II) complexes more closely resemble high-spin five-coordinate systems in the 1540 and 1345 cm
-1
regions, but in the 380 cm
-1
region the resemblance is closer to the low-spin six-coordinate tetraphenylporphyrin complexes. These results provide spectroscopic confirmation for the unique nature of these pseudo-six-coordinate complexes.
Spontaneous cancer and its possible relationship to oxygen metabolism.
Authors: Totter J R
Published: May 2006

Mortality statistics for cancer in various countries and periods of time indicate that there has been little effect of industrialization on the inherent or spontaneous rate of occurrence of cancer. From U.S. cancer statistics and the BEIR values [Report of the Advisory Committee on the Biological Effects of Ionizing Radiation (1979)] for radiation dose response, the ionizing radiation exposure required to produce a number of cancers equal to this spontaneous incidence was estimated to lie between 450 and 2100 rads (1 rad = 0.01 J/kg). From these "cancer equivalent" doses the number of single-strand DNA breaks required to produce the spontaneous cancers is estimated to be 0.26-1.3 per cell DNA per day. It is suggested that the univalent reduction of oxygen in normal metabolism to O2- and subsequent production of more harmful radicals is the source of the DNA defects that, in cases where the defense mechanisms fail, lead to spontaneous cancer in the individual.
Cytochrome oxidase: an alternative model.
Authors: Seiter C H , Angelos S G
Published: May 2006

Oxidative titration of reduced cytochrome oxidase (cytochrome c oxidase; ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1) in the presence of carbon monoxide and sulfide, at potentials greater than +500 mV (vs. the neutral hydrogen electrode), have failed to produce new copper signals in the electron paramagnetic resonance spectrum of this enzyme. This observation implies that once of the copper centers in cytochrome oxidase remains Cu(I) under strongly oxidizing conditions. The rationalization of this fact, and the possible explanation of a great accumulation of spectroscopic data, is that cytochrome a3 may be a two-electron redox center, with stable Fe(IV), Fe(III), and Fe(II) states during its redox cycle. This oxidase model does not require an antiferromagnetic coupling scheme, in contrast to currently prevalent models.
Isolation and characterization of calmodulin from spinach leaves and
in vitro
translation mixtures
Authors: Eldik Linda J. Van , Grossman Arthur R. , Iverson David B. , Watterson D. Martin
Published: May 2006

Calmodulin, a multifunctional calcium-modulated protein, has been isolated from spinach leaf tissue and from spinach leaf messenger RNA translation products. The translation protein and the spinach leaf protein have been partially characterized and compared to vertebrate calmodulins. Spinach leaf calmodulin will quantitatively activate bovine brain phosphodiesterase and will undergo a calcium-dependent shift in electrophoretic mobility similar to that of bovine brain calmodulin. In the presence of Ca
2+
the spinach and brain proteins comigrate, but in the presence of chelators they do not. A polyadenylylated RNA fraction has been isolated from spinach leaf tissue and translated in a wheat germ cell-free translation system. The calmodulin synthesized
in vitro
has been isolated by using calcium-dependent affinity chromatography on phenothiazine-Sepharose conjugates. The translation protein comigrates with spinach calmodulin during polyacrylamide gel electrophoresis whether in the presence or the absence of Ca
2+
. The translation protein also undergoes a calcium-dependent mobility shift identical to that of spinach calmodulin. Amino acid analysis of the translation calmodulin indicates that it does not contain

N
ε

-trimethyllysine, an amino acid residue that is characteristic of all calmodulins previously examined. These studies suggest that

N
ε

-trimethyllysine is not required for the calcium-dependent interaction of calmodulin with phenothiazines and indicate the potential utility of phenothiazine-Sepharose conjugates as affinity-based adsorbents in biological and biochemical investigations.
The lexA gene product represses its own promoter.
Authors: Brent R , Ptashne M
Published: May 2006

The products of the lexA and recA genes of Escherichia coli regulate the cellular response to DNA damage (the SOS response). Here we describe the cloning of the wild-type lexA gene and the identification of its 24,000-dalton protein product. We also describe construction, by recombination in vitro, of a phage that bears the lexA promoter fused to the lacZ gene. Experiments with this fusion phage and with multicopy plasmids that carry the lexA gene showed that the lexA gene product represses of its own promoter. This repression occurs even if the cell has no recA gene, showing that the lexA protein need not be complexed to the recA protein for activity. Moreover, the presence of multicopy plasmids that carry the lexA gene blocks expression of all SOS responses tested. This presumably results from two effects: (i) repression of the recA gene, the product of which is required to activate many of these responses; and (ii) direct repression of other functions involved in the SOS response.
Transcription of mouse kappa chain genes: implications for allelic exclusion.
Authors: Perry R P , Kelley D E , Coleclough C , Seidman J G , Leder P , Tonegawa S , Matthyssens G , Weigert M
Published: May 2006

The nuclear RNA from a large variety of kappa-producing plasmacytomas was size fractionated and analyzed with a series of cloned probes representing sequences encoding variable (V), joining (J), and constant (C) regions and selected intervening sequences. All of the plasmacytomas produce a nuclear RNA component that contains V kappa and C kappa sequences as well as the intervening sequence between J kappa and C kappa, and that has a distinctive size depending on which of the four J kappa segments is expressed (i.e., is present in the secreted kappa chain). These RNAs are the precursors of kappa mRNAs, which are transcribed from productively rearranged C kappa genes. Half of the plasmacytomas examined produce, in addition to a kappa mRNA precursor, a discrete component of about 8.4 kilobases that contains C kappa and upstream flanking sequences but lacks the expressed V region sequence. The ability to produce this component is always associated with the persistence in the tumor genome of an unrearranged (germline) J kappa-C kappa region. In tumors rearranged at both kappa loci the nonproductive allele is either transcriptionally silent or, in a minority of cases, transcribed and processed into a "fragment" mRNA lacking V region sequences. These results reveal that allelic exclusion can be effected at several levels of gene expression. They also provide some insight into the relative contributions of the V and C gene elements to this expression.
Binding of diphtheria toxin to phospholipids in liposomes
Authors: Alving Carl R. , Iglewski Barbara H. , Urban Katharine A. , Moss Joel , Richards Roberta L. , Sadoff Jerald C.
Published: May 2006

Diphtheria toxin bound to the phosphate portion of some, but not all, phospholipids in liposomes. Liposomes consisting of dimyristoyl phosphatidylcholine and cholesterol did not bind toxin. Addition of 20 mol% (compared to dimyristoyl phosphatidylcholine) of dipalmitoyl phosphatidic acid, dicetyl phosphate, phosphatidylinositol phosphate, cardiolipin, or phosphatidylserine in the liposomes resulted in substantial binding of toxin. Inclusion of phosphatidylinositol in dimyristol phosphatidylcholine/cholesterol liposomes did not result in toxin binding. The calcium salt of dipalmitoyl phosphatidic acid was more effective than the sodium salt, and the highest level of binding occurred with liposomes consisting only of dipalmitoyl phosphatidic acid (calcium salt) and cholesterol. Binding of toxin to liposomes was dependent on pH, and the pattern of pH dependence varied with liposomes having different compositions. Incubation of diphtheria toxin with liposomes containing dicetyl phosphate resulted in maximal binding at pH 3.6, whereas binding to liposomes containing phosphatidylinositol phosphate was maximal above pH 7. Toxin did not bind to liposomes containing 20 mol% of a free fatty acid (palmitic acid) or a sulfated lipid (3-sulfogalactosylceramide). Toxin binding to dicetyl phosphate or phosphatidylinositol phosphate was inhibited by UTP, ATP, phosphocholine, or
p
-nitrophenyl phosphate, but not by uracil. We conclude that (
a
) diphtheria toxin binds specifically to the phosphate portion of certain phospholipids, (
b
) binding to phospholipids in liposomes is dependent on pH, but is not due only to electrostatic interaction, and (
c
) binding may be strongly influenced by the composition of adjacent phospholipids that do not bind toxin. We propose that a minor membrane phospholipid (such as phosphatidylinositol phosphate or phosphatidic acid), or that some other phosphorylated membrane molecule (such as a phosphoprotein) may be important in the initial binding of diphtheria toxin to cells.
Leukotriene D: a slow reacting substance from rat basophilic leukemia cells.
Authors: Orning L , Hammarström S , Samuelsson B
Published: May 2006

A slow reacting substance produced by rat basophilic leukemia cells, treated with ionophore A23187, was characterized by spectroscopic methods, enzymatic conversions, and chemical degradations as 5-hydroxy-6-S-cysteinylglycyl 7,9,11,14-eicosatetraenoic acid (leukotriene D). gamma-Glutamyltranspeptidase [gamma-glutamyltransferase; (5-glutamyl)-peptide: amino-acid 5-glutamyltransferase, EC 2.3.2.2] converted leukotriene C to a product identical to leukotriene D. This suggests that the stereochemistry of the arachidonyl moiety of leukotrienes C and D is the same [5(S)-6(R)-7,9-trans-11,14-cis]. Leukotriene D induces a faster contraction and, on a molar basis, is more potent than leukotriene C in the isolated guinea pig ileum bioassay.
Use of collagen-hydroxyethylmethacrylate hydrogels for cell growth.
Authors: Civerchia-Perez L , Faris B , LaPointe G , Beldekas J , Leibowitz H , Franzblau C
Published: May 2006

Collagen-hydroxyethylmethacrylate hydrogels were prepared by polymerizing monomeric hydroxyethylmethacrylate in the presence of various concentrations of soluble native collagen. The resulting transparent hydrogels were evaluated as substrata for growth of IMR-90 human embryonic lung fibroblasts. Without collagen no significant growth occurred, whereas a dose-response curve expressing maximal cell growth against collagen concentration could be constructed quite readily by the use of appropriate hydrogels. The method allows for quantification of the collagen contribution to cell growth and, in a more general sense, provides the foundation for a relatively easy procedure to probe mechanisms of cell adhesion and cell differentiation.
Macromolecular beta-adrenergic antagonists discriminating between receptor and antibody.
Authors: Pitha J , Zjawiony J , Lefkowitz R J , Caron M G
Published: May 2006

The beta-adrenergic antagonist, alprenolol, was attached in an irreversible manner to macromolecular dextran via side arms that differed in length. The ability of these macromolecules to bind to the beta-adrenergic receptor of frog erythrocytes and to catecholamine-binding antibodies raised against partially purified receptors was studied. Compared to the parent drug the potency of binding of macromolecular alprenolol to the receptor decreased about 1/10, 1/600, and 1/8000 when the length of the arm separating alprenolol from the dextran moiety was 13, 8, and 4 atoms, respectively. In contrast, the binding potencies of the parent drug and of all its macromolecular derivatives for the antibody were within the same order of magnitude. Thus, conversion of a drug to a macromolecular form may not only sustain its binding activity but may also lead in a higher selectivity. The macromolecular derivatives described here may be suitable probes for investigation of the location and of the molecular properties of the binding sites for beta-adrenergic drugs.
Measurements of the pH within dormant and germinated bacterial spores.
Authors: Setlow B , Setlow P
Published: May 2006

The pH within the core or central region of dormant spores of Bacillus cereus and B. megaterium is 6.3-6.4 irrespective of the external pH. However, the spore's internal pH rises to 7.3-7.5 upon germination. The low internal pH of the dormant spore may be a contributing factor to its metabolic dormancy.
Functional incorporation of synthetic glycolipids into cells.
Authors: Rando R R , Slama J , Bangerter F W
Published: May 2006

Synthetic glycolipids containing an alpha-mannoside group linked by a hydrophilic spacer arm to cholesterol were incorporated into bovine erythrocytes by exchange from glycolipid-containing liposomes. When the distance between the sugar and the cholesterol moieties was approximately 26 A, functional incorporation of these glycolipids could be easily detected, as revealed by the concanavalin A-mediated agglutination of these cells. Bovine erythrocytes are not themselves susceptible to concanavalin A-mediated agglutination. The minimal concentration of concanavalin A required for agglutination of modified erythrocytes, containing 9.15 x 10(6) glycolipid molecules per cell, was 4 microgram/ml. Under these conditions, only approximately 4% of the membrane-bound cholesterol had been exchanged for the synthetic glycolipid. The observed aggregation was reversible in the presence of alpha-methyl mannoside and did not occur when beta-galactosyl-containing glycolipids were used in place of their alpha-mannoside isomers. These studies demonstrate a technique of sugar incorporation into cell membranes which should be of great advantage in studies on the roles of cell surface sugars in biological recognition. Furthermore, they demonstrate that the sugars need only be a short distance (26 A) from the membrane in order to functionally bind concanavalin A.
A phospholipase A2 inhibitory protein in rabbit neutrophils induced by glucocorticoids.
Authors: Hirata F , Schiffmann E , Venkatasubramanian K , Salomon D , Axelrod J
Published: May 2006

When rabbit peritoneal neutrophils were treated with glucocorticoids, their chemotactic response to stimulation by the chemoattractant fMet-Leu-Phe was markedly reduced. Preincubation of cells with glucocorticoids also decreased phospholipase A2 (phosphatide 2-acylhydrolase, EC 3.1.1.4) activity in situ as measured by the release of [1-14C]arachidonic acid previously incorporated into phospholipids. The inhibitory potencies of glucocorticoids on phospholipase A2 activity correlated well with their anti-inflammatory activities and their abilities to bind to glucocorticoid receptors. Inhibitors of RNA and protein synthesis suppressed the inhibitory effect of glucocorticoids on phospholipase A2 activity. Digestion of the glucocorticoid-treated cells by Pronase overcame the inhibitory activity. Phospholipase A2 activity induced by Ca2+ ionophore A23187 was not affected by Pronase treatment. Gel filtration of proteins from neutrophil membranes labeled with [3H]lysine showed an induction of protein(s) (about 40,000 daltons) after glucocorticoid treatment. This protein inhibited a partially purified pancreatic phospholipase A2 and reduced the peptide-initiated chemotactic response of neutrophils.
Structure of a split yeast gene: complete nucleotide sequence of the actin gene in Saccharomyces cerevisiae.
Authors: Gallwitz D , Sures I
Published: May 2006

The complete nucleotide sequence of the actin gene from Saccharomyces cerevisiae has been determined. The coding region is interrupted by a 304-base-pair intervening sequence that is located within the triplet coding for amino acid 4. DNA sequences of the intron-exon junctions are similar to those found in higher eukaryotes and can be aligned such that the intron starts with the dinucleotide 5'-G-T-3' and ends with 5'-A-G-3'. Regions fo homology within the sequences upstream from the initiation codon and those following the termination codon have been detected between the yeast iso-1-cytochrome c gene and the actin gene. As deduced from the nucleotide sequence, yeast actin has 374 amino acid residues. Its primary structure, especially the NH2-terminal third of the protein, is highly conserved during evolution.
Three-dimensional structure of a pyridoxal-phosphate-dependent enzyme, mitochondrial aspartate aminotransferase.
Authors: Ford G C , Eichele G , Jansonius J N
Published: May 2006

X-ray diffraction studies to 2.8-A resolution have yielded the three-dimensional structure of mitochondrial aspartate aminotransferase (L-aspartate:2-oxoglutarate aminotransferase, EC 2.6.1.1), an isologous alpha 2 dimer (Mr = 2 x 45,000). The subunits are rich in secondary structure and contain two domains, one of which anchors the coenzyme, pyridoxal 5'-phosphate. Each active site lies between the subunits and is composed of residues from both of them.
Analysis of the closely linked adult chicken alpha-globin genes in recombinant DNAs.
Authors: Engel J D , Dodgson J B
Published: May 2006

Recombinant bacteriophage (from a library of chicken chromosomal DNA fragments inserted into lambda Charon 4A) have been isolated which contain the coding information for both of the adult chicken alpha-globin genes, alpha A and alpha D. One of these recombinant phage also contains an as yet unidentified embryonic alpha-like globin gene sequence. The two adult genes are encoded on the same DNA strand and are separated by approximately 2.4 kilobase pairs, with the arrangement of the genes relative to the direction of transcription being 5'-alpha D-alpha A-3'. Electron microscopic R-loop visualization experiments demonstrate that both alpha-globin genes contain two intervening sequences of similar size in a manner analogous to the structure observed in the mouse alpha-globin gene. The linkage of the two highly divergent chicken adult alpha-globin genes further underscores the principle that chromosomal clustering of families of developmentally related genes may be a general phenomenon in higher eukaryotic gene sequence arrangement.
Q beta replicase template specificity: different templates require different GTP concentrations for initiation.
Authors: Blumenthal T
Published: May 2006

Qbeta replicase is notable for its high degree of template specificity. It has been shown to transcribe Qbeta RNA and synthetic polymers containing cytidylate. However, other natural RNAs are not transcribed unless Mn2+ ions are present. The enzyme initiates all RNA synthesis with GTP. In this report it is shown that Qbeta replicase can transcribe heterologous natural RNA species in the absence of Mn2+ if sufficient GTP is present. Each RNA tested requires a different GTP concentration for initiation. These results indicate that the site for the initiating nucleoside triphosphate on Qbeta replicase is strongly influenced by the template. It is proposed that the high degree of template specificity is a consequence of the fact that different templates induce initiation sites with varying affinities for GTP. Two lines of evidence support this idea. First, Mn2+ ions, which reduce template specificity, reduce the concentration of GTP required for initiation. Second, high ionic strength, which decreases transcription of all templates except Qbeta RNA, increases the GTP requirement. The possibility is considered that variable promoter or ribosome binding site strengths could result from a mechanism similar to that proposed here.
Regulation of the synthesis of glutamine synthetase by the PII protein in Klebsiella aerogenes.
Authors: Foor F , Reuveny Z , Magasanik B
Published: May 2006

Certain mutations at the glaB locus result in the failure to fully derepress glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2] and to convert it to the active nonadenylylated form in response to nitrogen limitation. In these mutants the PII regulatory protein is altered such that it cannot be converted by uridylyltransferase to the form stimulating deadenylylation of glutamine synthetase by adenylyltransferase. Additional mutations as well as insertions of transposon Tn5 at the glnB site result in the loss of PII. The loss of PII does not prevent adenylylation and deadenylylation of glutamine synthetase but reduces the rates of these reactions. Cells lacking PII have a high level of glutamine synthetase even when they are grown with an excess of ammonia and the enzyme is highly adenylylated. The results suggest that the PII protein plays a role, independent of its effect on adenylylation, in the regulation of the level of glutamine synthetase.
Plasmid-dependent temperature-sensitive phase in crown gall tumorigenesis
Authors: Rogler Charles E.
Published: May 2006

Two methods have been used to show that the temperature-sensitive (ts) genes for plasmid maintenance located on pTiC58 are responsible for the presence of a specific 37°C ts period during crown gall tumorigenesis. Tumors induced by
Agrobacterium tumefaciens
strain C58 become resistant to 32°C by 96 hr after infection, indicating that the “inception phase” of crown gall is complete at that time. However, C58 tumors remain sensitive to 37°C until 168 hr after infection. When pTiC58 is replaced in strain C58 by a plasmid that is temperature resistant for maintenance within the bacterium at 37°C (B
6
806) the tumors induced by the new strain (A277) become resistant to 37°C by 96 hr after infection. Furthermore, when pTiC58 is selected for temperature resistance in strain C58 at 37°C, the tumors induced by the new strain, C58
TR
, become resistant to 37°C approximately 40 hr earlier than do tumors induced by the parent strain C58. These results prove that the 37°C ts period (96-168 hr after infection) is coded for ts plasmid maintenance genes located on pTiC58. Incorporation of [
3
H]-thymidine into pTiC58 in strain C58 is specifically inhibited at 37°C compared to chromosomal DNA and is not inhibited at 32°C. The data presented support a mechanism in which the 37°C, ts period between 96 and 168 hr after infection is due to the requirement for the plasmid-coded maintenance genes involved in plasmid replication within incipient tumor cells. The fact that the 37°C ts period ends after 168 hr indicates a transient requirement for the ts gene product, perhaps due to the stable integration of plasmid DNA into plant genetic elements by that time.
Control of guinea pig intestinal electrolyte secretion by a delta-opiate receptor.
Authors: Kachur J F , Miller R J , Field M
Published: May 2006

The effects of opioids on transepithelial potential difference and short-circuit current across guinea pig ileum stripped of one muscle layer were measured in vitro in Ussing chambers. Opioid peptides such as [DAla2, DLeu5]enkephalin and [DAla2, DMet5]enkephalin, which are primarily agonists at delta-opiate receptors, were able to reduce transepithelial potential difference and short-circuit current at concentrations as low as 1 nM. The narcotic drug etorphine was also very potent in reducing short-circuit current, but fentanyl and morphine, which are primarily agonists at mu-opiate receptors, were almost completely ineffective. Ketocyclazocine was relatively ineffective, and beta-endorphin had intermediate potency. All opioid effects could be reversed by the opiate antagonist naloxone. Somatostatin also reduced short-circuit current, but its effect was not reduced by naloxone. Chloride flux measurements indicated that the effect of etorphine on short-circuit current is associated with an enhancement of active Cl- absorption. The relative effects of opioids in this system suggest that their actions are being mediated by a specific delta-opiate receptor. In contrast, opioid effects on guinea pig intestinal smooth muscle seem to be primarily mediated by a mu-opiate receptor.
Unusual alpha-globin-like gene that has cleanly lost both globin intervening sequences.
Authors: Nishioka Y , Leder A , Leder P
Published: May 2006

We have cloned and determined the nucleotide sequence of a mouse alpha-globin-like gene that entirely lacks the two intervening sequences that interrupt all globin genes thus far examined. The fact that this gene, alpha-3, is closely homologous to the normal adult alpha gene sequence suggests that it arose after the alpha/beta divergence and that it therefore must have lost its intervening sequences. The further fact that these intervening sequences have been lost cleanly--that is, in according with the G-T/A-G splicing rule of RNA--suggests, among other possibilities, that their loss may have been brought about by a gene conversion event involving the mediation of mature globin mRNA or its cDNA cognate. We propose such a mechanism that would permit the loss of either or both intervening sequences independently. Only the loss of both, however, should result in the inactivation of the globin gene, as seems to be the case with alpha-3.
Immunologic effects of whole-body ultraviolet irradiation: selective defect in splenic adherent cell function in vitro.
Authors: Letvin N L , Greene M I , Benacerraf B , Germain R N
Published: May 2006

Splenocytes from mice receiving whole-body UV irradiation do not make a normal primary in vitro plaque-forming cell (PFC) response to the soluble T-dependent antigen trinitrophenylated poly(L-glutamic acid60L-alanine30L-tyrosine10). This impaired immune response results from a selective loss of antigen-presenting cell function in the splenic adherent cell (SAC) population of the UV-treated mice. SACs from UV-irradiated mice are unable to reconstitute a PFC response when added to normal splenocytes passed through Sephadex G-10 (which depletes adherent cells), whereas normal SACs, when added to Sephadex G-10-passed splenocytes from UV-treated mice, do restore a PFC response. The effect of in vivo UV irradiation on the SAC population is indistinguishable functionally from the effect of in vitro UV irradiation of SACs from normal mice. Possible explanations for this selective effect of external UV irradiation on SAC function are discussed.
Presence of allograft-rejection resistance in simian virus 40-transformed hamster cells and its possible role in tumor development.
Authors: Lewis A M , Cook J L
Published: May 2006

LSH Syrian hamster cells transformed in vitro by simian virus 40, which is oncogenic for hamsters, are resistant to rejection by adult allogeneic CB hamsters. In contrast, simian virus 40-transformed cells from other species are usually not oncogenic in immunocompetent autologous or isologous hosts. The ability of simian virus 40 to convey resistance to an allograft-type host response to transformed hamster cells may be important in determining the tumor-inducing capacity of these cells and could, in part, explain the species-specific oncogenicity of this virus.
Induction of differentiation of the human promyelocytic leukemia cell line (HL-60) by retinoic acid.
Authors: Breitman T R , Selonick S E , Collins S J
Published: May 2006

The HL-60 cell line, derived from a patient with acute promyelocytic leukemia, proliferates continuously in suspension culture and consists predominantly (greater than 90%) of promyelocytes. These cells can be induced to differentiate to morphologically and functionally mature granulocytes by incubation with a wide variety of compounds, including butyrate and hypoxanthine and polar planar compounds such as dimethyl sulfoxide and hexamethylene bisacetamide. We have now found that retinoic acid (all-trans-retinoic acid) induces differentiation (as measured morphologically and by the ability to reduce nitroblue tetrazolium) of HL-60 at concentrations as low as 1 nM. Maximal differentiation (approximately 90%) occurs at 1 micro M, a concentration 1/500th to 1/160,000th the concentrations of butyrate (0.5 mM) and dimethyl sulfoxide (160 mM) that promote a similar increase in differentiation. Continuous exposure to retinoic acid is necessary for optimal differentiation, with the percentage of mature cells in the culture directly related to the length of time of exposure to retinoic acid. Retinoic acid and 13-cis-retinoic acid are equally effective in inducing differentiation of HL-60. Retinol (vitamin A), retinal, and retinyl acetate are approximately 1/1000th less potent. This study suggests that retinoids could provide a therapeutic tool in the treatment of acute myeloid leukemia, a disease that has been looked upon as primarily involving a block in myeloid differentiation, and indicates that retinoids, in addition to their well-characterized involvement in epithelial cell differentiation, may also be involved in the differentiation of certain hematopoietic cells.
In vitro construction of a B-tropic virus by recombination: B-tropism is a cryptic phenotype of xenotropic murine retroviruses.
Authors: Gautsch J W , Elder J H , Jensen F C , Lerner R A
Published: May 2006

A B-tropic virus was isolated in vitro from the progeny of mouse cells doubly infected with N-tropic and xenotropic murine leukemia viruses. Biological and structural evidence is presented suggesting that the phenotypically silent structural marker for B-tropism, expressed by the xenotropic virus p30, was transferred to an N-ecotropic virus via recombination, thus resulting in the expression of a B-ecotropic murine leukemia virus.
Structure and phosphorylation of microtubule-associated protein 2 (MAP 2).
Authors: Vallee R
Published: May 2006

Chymotryptic fragments of microtubule-associated protein 2 (MAP 2) containing the portion of the molecule responsible for promoting microtubule assembly were identified. These assembly-promoting fragments displaced intact MAP 2, but not MAP 1, from assembled microtubules. This indicates that the association of MAP 2 with the microtubule surface is reversible. Both the assembly-promoting fragments and fragments representing the portion of the MAP 2 molecule observed as a projection on the microtubule surface were found to contain sites for endogenous cyclic AMP-dependent phosphorylation. The projection fragments were capable of endogenous phosphorylation even after their physical separation from microtubules. This suggests an intimate association of a kinase activity with the projections. Detailed analysis of the properties of the chymotryptic fragments of MAP 2 has led to a map of the molecule showing the major sites of proteolytic attack and the sites of phosphorylation.
Characterization of retinoyl beta-glucuronide as a minor metabolite of retinoic acid in bile.
Authors: Zile M H , Schnoes H K , DeLuca H F
Published: May 2006

Several metabolites detected in the bile of rats given radioactive retinoic acid were separated by liquid/gel partition chromatography and purified by high-pressure liquid chromatography. One of these metabolites was found to be sensitive to beta-D-glucuronidase, yielding both 13-cis- and all-trans-retinoic acid. It had the characteristic ultraviolet absorption spectrum of retinoic acid esters. Trimethylsilyl ether and acetyl derivatives of the methylated metabolite were prepared and examined by mass spectrometry. The resulting mass spectra established the structure to be retinoyl beta-glucuronide. Retinoyl glucuronide was rapidly excreted into the bile: the excretion was complete by 12 hr after the administration of retinoic acid. At this time the metabolite represented 12% of bile radioactivity (10% of dose). These observations confirm the existence of retinoyl glucuronide but demonstrate that it represents only one of several retinoic acid metabolites in bile.
Regulation of acetyl-coA carboxylase: properties of coA activation of acetyl-coA carboxylase.
Authors: Yeh L A , Kim K H
Published: May 2006

Acetyl-CoA carboxylase [acetyl-CoA:carbon-dioxide ligase (ADP-forming), EC 6.4.1.2] is activated by physiological concentrations of CoA. The CoA concentration dependency of this activation is sigmoidal; below 60 microM there is little or no activation, but the activation observed between 60 and 120 microM indicates that small changes in the concentration of CoA can cause significant changes in carboxylase activity. CoA activation of acetyl-CoA crboxylase accompanies polymerization of acetyl-CoA carboxylase. However, the binding site for CoA appears to be different from that of citrate. In contrast to citrate activation, which changes only the Vmax of the reaction, CoA activation of carboxylase results in polymeric forms with a lower Km for acetyl-CoA. The Km for acetyl-CoA is 0.4 mM in the control enzyme, whereas that of the CoA-activated enzyme is as low as 4 microM. The Km for ATP was not changed. Derivatives of CoA were not effective in activating the carboxylase, indicating that the CoA effect is specific. Arguments are presented that CoA could be a physiologically significant positive effector of the carboxylase.
Calculations of the circular dichroism of adenosine derivatives constrained in the
syn
form
Authors: Miles Daniel W. , Farmer Morris , Eyring Henry
Published: May 2006

The rotational strengths of the four longer wavelength transitions,
B

2
u

,
B

1
u

, and the two
E

1
u

, of adenosine derivatives constrained in the
syn
form have been investigated theoretically and experimentally. The theory combines a complete neglect of differential overlap version S (CNDO/S) description of the base with a generalized bond exciton method by means of a matrix method. Rotational strength wheels for these transitions showing the rotational strength as a function of the glycosidic rotational angles are presented and sector rules discussed. Similar sector rules are predicted for purine nucleoside derivatives containing the 6-amino substituent, regardless of heteroatom content at positions 1 or 3 of the base. The sector rules for the
B

2
u

rotational strength of purine nucleosides lacking the 6-amino substituent are strongly influenced by aza substitution. The circular dichroism spectra of 3-deazaadenosine, 8-(α-hydroxyisopropyl)-adenosine, and other purine nucleosides having a strong preference for the
syn
conformation are presented and compared with the theoretical results.
Carbohydrate-binding component of amphibian embryo cell surfaces: Restriction to surface regions capable of cell adhesion
Authors: Roberson Marie M. , Armstrong Peter B.
Published: May 2006

Superficial cells from early amphibian embryos display regional specializations of their cell surfaces. That portion of the plasma membrane facing the perivitelline space (apical surface) is nonadhesive, whereas, in the same cell, the lateral and basal portions of the plasma membrane will adhere to other cells. These adhesive differences are maintained on single cells that have been dissociated from the intact embryo. Extracts of cleavage-stage
Rana pipiens
embryos are capable of agglutinating formalinized sheep erythrocytes. The hemagglutination activity can be blocked by a yeast mannan and a family of glycoproteins containing high levels of mannose, indicating the presence of a lectin with oligomannosyl specificity. The cell surface location of this carbohydrate-binding component can be demonstrated by the ability of the formalinized sheep erythrocytes to form rosettes with living dissociated embryonic superficial cells. Rosette formation is blocked by the same inhibitors that are effective in blocking the activity of the crude extracts. The formalinized sheep erythrocytes form rosettes only to those cell surface regions of the superficial cells that are capable of adhering to other amphibian embryo cells. Receptors for concanavalin A, a lectin that binds D-mannose and D-glucose residues, have also been shown to be present exclusively over the adhesive regions of the superficial cells. The involvement of a carbohydrate-binding component with oligomannosyl specificity in the adhesive mechanisms of these cells is suggested by this restriction of both the embryonic amphibian lectin and its possible receptors (concanavalin A receptors) to adhesive regions of the cell surface.
Biological activity of cloned Moloney sarcoma virus DNA: Terminally redundant sequences may enhance transformation efficiency.
Authors: Blair D G , McClements W L , Oskarsson M K , Fischinger P J , Vande Woude G F
Published: May 2006

We have measured the ability of cloned restriction fragments containing the whole and partial genomes of two strains of Moloney murine sarcoma virus to induce cell transformation in DNA transfection assays. The cloned intact ml and HTl murine sarcoma virus proviruses transform with an efficiency of approximately 40,000-50,000 focus-forming units/pmol of proviral DNA, and the majority of these transformed cells contain a rescuable viral genome. A cloned 2.1-kilobase-pair internal fragment of the murine sarcoma virus containing 1.2 kilobase pairs of sarcoma virus-specific sequences (src) and approximately 900 base pairs of leukemia virus-derived sequences adjacent to the 5' end of src transforms with approximately 1/10,000th the efficiency of the intact genome. When leukemia virus-deprived sequences containing a single copy of the 600-base-pair direct terminal repeated sequences are present at either the 5' or 3' end of this src-containing fragment, the transforming activity is stimulated 1000-fold. Cotransfection with a mixture of cloned fragments, one containing the internal 2.1-kilobase-pair src fragment and the other containing a single copy of the terminally redundant sequence, results in a 300-fold increase in transformation efficiency.
Predicting coding function from nucleotide sequence or survival of "fitness" of tRNA.
Authors: Pieczenik G
Published: May 2006

The sequence of a nucleotide region of f1 bacteriophage was determined on a bonded ultrathin acrylamide gel with a discontinuous buffer system by using the dideoxy-DNA sequencing method. This sequence and one other were analyzed for maximal base pairing with tRNAs. The results allow a prediction of the direction and phase of possible coding functions. The implication of sequence constraints on mRNA codon frequency, tRNA structure, the origin of protein synthesis, and triplet reading are discussed in terms of neutral, Darwinian, and genotypic selectionist perspectives of evolution. The model of F. H. C. Crick, S. Brenner, A. Klug, and G. Pieczenik [(1976) Origins of Life 7, 389-397] for the origin of the genetic code is used to interpet contemporary adaptive and functional nucleic acid sequences.
Comparative gene mapping: order of loci on the X chromosome is different in mice and humans.
Authors: Francke U , Taggart R T
Published: May 2006

For comparative studies we have used the somatic cell hybridization approach to regionally map genes on the mouse X chromosome. Fibroblasts from a mouse with the balanced reciprocal translocation T(XD;16B5)16H were fused with a Chinese hamster cell line (V79/380-6) deficient in activity of the enzyme hypoxanthine phosphoribosyltransferase (HPRT). Interpecific cell hybrids were initially selected for retention of the mouse translocation chromosome carrying the Hprt gene. Subsequently, hybrid clones were counterselected to force segregation of this chromosome. Selected and counterselected hybrid clones were analyzed for their chromosome content by trypsin/Giemsa banding and for expression of the mouse forms of the X-linked enzymes HPRT and alpha-galactosidase (GALA) by isoelectric focusing. The results indicate that the breakpoint on the mouse X chromosome (in band XD) has separated the genes for HPRT (Hprt) and for GALA (Ags). Hprt is proximal to the breakpoint in region Xcen-XD and Ags is distal in region XD-Xter. The gene order in the mouse (centromere-Hprt-Ags) is therefore inverted when compared to the order of the homologous loci on the long arm of the human X (centromere-GALA-HPRT).
Metabolic resource allocation vs. mating attractiveness: Adaptive pressures on the “alba” polymorphism of
Colias
butterflies
Authors: Graham Scott M. , Watt Ward B. , Gall Lawrence F.
Published: May 2006

The sex-limited “alba” genetic polymorphism in wing color of
Colias
butterflies has been studied with respect to potential selective pressures on this locus. Alba female pupae, carrying at least one dominant
A
allele, redirect resources, used by
aa
pupae for pigmentation, to other metabolic ends. Associated with this reallocation, alba,
A
-, female adults eclose earlier, retain more larva-derived resources in their fat bodies for somatic maintenance and for reproduction, and, in some conditions, mature their eggs faster than do
aa
females. Alba females are also less attractive to males than are
aa
females and mate less frequently. Evolutionary implications of these results are discussed.