bluuebunny/crossref_metadata_2025 huggingface dataset:
Modified recombination and transmission of mitochondrial genetic markers in rho minus mutants of Saccharomyces cerevisiae.
Authors: Boltin-Fukuhara M , Fukuhara H
Published: May 2006

A large number of primary petite (rho-) clones were isolated after ethidium bromide mutagenesis of various grande (rho+) strains of S. cerevisiae that contained the mitochondrial genetic markers, CR, ER, OIR (or OIIR), and PR. From the frequency of coretention of markers in the petites, we have deduced a probable circular order of the markers in the grande mitochondrial genome. From these primary clones several series of pure and stable petite clones were obtained and analyzed genetically. (a) In general, the omega allele is retained or lost together with the region carrying both CR and ER markers. (b) The petites that have retained only the CR marker fall into two classes: some have kept the omega allele of the grande strain they issued from; others exhibit a new omega expression. (c) The proportion of diploid petites in petite X grande crosses is independent of the presence of the omega allele. (d) In most cases, the coordinated transmission of markers observed so far in all grande X grande nonpolar corsses does not exist anymore in petites.
Simultaneous detection of reverse transcriptase and high molecular weight RNA in tissue of patients with Hodgkin's disease and patients with leukemia.
Authors: Chezzi C , Dettori G , Manzari V , Aglianò A M , Sanna A
Published: May 2006

Complexes of high-molecular-weight RNA and reverse transcriptase (RNA-dependent DNA nucleotidyltransferase) have been detected in 14(77.8%) of 18 spleen from patients with Hodgkin's disease and in all samples tested of peripheral leukocytes and spleens from leukemic patients. The enzyme and its template are localized in a particle having a density between 1.16 and 1.19 g/ml. These observations describe characteristic features of RNA tumor viruses.
Position of aminoacylation of individual Escherichia coli and yeast tRNAs.
Authors: Hecht S M , Chinualt A C
Published: May 2006

Transfer RNAs terminating 2'-or 3'-deoxyadenosine were prepared from unfractionated E. coli and yeast (Saccharomyces cerevisiae) tRNAs and purified to remove unmodified tRNAs. The modified tRNA species were assayed for aminoacylation with each of the 20 amino acids to determine the initial position of tRNA aminoacylation. The E. coli and yeast aminoacyl-tRNA synthetases specific for arginine, isoleucine, leucine, methionine, phenylalanine, and valine, as well as the E. coli glutamyl-tRNA synthetase, aminoacylated only those cognate tRNAs terminating in 3'-deoxyadenosine (i.e., those having a 2'-OH group). On the other hand, those E. coli and yeast synthetases specific for alanine, glycine, histidine, lysine, proline, serine, and threonine, as well as the yeast synthetase specific for glutamine, utilized exclusively those tRNAs having an available 3'-OH group on the 3'-terminal nucleoside, while the E. coli and yeast synthetases specific for asparagine, cysteine, and tyrosine, and the yeast aspartyl-tRNA synthetase, utilized both of the modified cognate tRNAs. The only observed difference in specificity between the E. coli and yeast systems was for tRNATrp, which was aminoacylated on the 2'-position in E. coli and the 3'-position in yeast. The results indicate that the initial position of aminoacylation is not uniform for all tRNAs, although for individual tRNAs the specificity has been conserved during the evolution from a prokaryotic to eukaryotic organism.
Interferon: purification and initial characterization from human diploid cells.
Authors: Knight E
Published: May 2006

Interferon produced by human diploid fibroblast cells in culture has been purified approximately 5000-fold. The purified interferon, when analyzed by electrophoresis on polyacrylamide gel containing sodium dodecyl sulfate, contains only one polypeptide component of 20,000 molecular weight. The interferon activity comigrates with this polypeptide, indicating identity of the activity and the polypeptide. Oxidation of this polypeptide with periodic acid and subsequent staining with Fuchsin base indicates that it contains carbohydrate ans suggests that the human fibroblast interferon is a glycoprotein.
New gene locus modifying susceptibility to certain B-tropic murine leukemia viruses.
Authors: Declève A , Niwa O , Kojola J , Kaplan H S
Published: May 2006

A new gene, SRV, the dominant allele of which occurs in mice of strain C57BL, independently modifies the slope ("hitness") and level of sensitivity of the titration curves obtained when one subclass of B-tropic murine leukemia viruses is propagated on mouse embryo cells of nonpermissive Fv-1 genotypes. Replication of another subclass of B-tropic viruses is not modified with respect to hitness, and that of N-tropic viruses is not affected.
Antagonism of 5-hydroxykynurenamine against serotonin action on platelet aggregation.
Authors: Okuma M , Tokuyama T , Senoh S , Hirata F , Hayaishi O
Published: May 2006

Serotonin induced an aggregation of human platelets, whereas 5-hydroxykynurenamine, produced from serotonin by the action of indoleamine 2,3-dioxygenase, did not cause any significant degree of platelet aggregation. 5-Hydroxykynurenamine specifically inhibited both a serotonin-induced aggregation of platelets and the potentiation of the ADP-induced platelet aggregation by serotonin. It did not, however, alter the profiles of the platelet aggregation induced by ADP, collagen, or adrenaline. The degree of inhibition was proportional to the time of preincubation of platelets with 5-hydroxykynurenamine, and to the concentration of 5-hydroxykynurenamine used. Available evidence indicated that 5-hydroxykynurenamine completed with serotonin for the same receptor sites. Studies with analogues of 5-hydroxykynurenamine indicated that the substitutions of 0-amino-benzyl moiety with hydroxy or methoxy groups were somewhat tolerated, whereas the masking of alkylamine moiety with N-acetylation completely lost the inhibitory activity.
A relativistic spherical vortex
Authors: Pekeris C. L.
Published: May 2006

This investigation is concerned with stationary relativistic flows of an inviscid and incompressible fluid. In choosing a density-pressure relation to represent relativistic “incompressibility,” it is found that a fluid in which the velocity of sound equals the velocity of light is to be preferred for reasons of mathematical simplicity. In the case of axially symmetric flows, the velocity field can be derived from a stream function obeying a partial differential equation which is nonlinear. A transformation of variables is found which makes the relativistic differential equation linear. An exact solution is obtained for the case of a vortex confined to a stationary sphere. One can make all three of the components of velocity vanish on the surface of the sphere, as in the nonrelativistic Hicks spherical vortex. In the case of an isolated vortex on whose surface the pressure is made to vanish, it is found that the pressure at the center of the sphere becomes negative, as in the nonrelativistic case.

A solution is also obtained for a relativistic vortex advancing in a fluid. The sphere is distorted into an oblate spheroid. The maximum possible velocity of advance of the vortex is (2/3)
c
.
Detection of carcinogens as mutagens in the Salmonella/microsome test: assay of 300 chemicals: discussion.
Authors: McCann J , Ames B N
Published: May 2006

About 300 carcinogens and non-carcinogens of a wide variety of chemical types have been tested for mutagenicity in the simple Salmonella/microsome test. The test uses bacteria as sensitive indicators of DNA damage, and mammalian liver extracts for metabolic conversion of carcinogens to their active mutagenic forms. There is a high correlation between carcinogenicity and mutagenicity: 90% (157/175) of the carcinogens were mutagenic in the test, including almost all of the known human carcinogens that were tested. Despite the severe limitations inherent in defining non-carcinogenicity, few "non-carcinogens" showed any degree of mutagenicity [McCann et al. (1975) Proc. Nat. Acad. Sci. USA 72, 5135-5139]. In the present paper, carcinogens negative in the test andapparent false positives are discussed. We also discuss evidence that chemical carcinogens and radiation, likely to initiate most human cancer and genetic defects do so by damage to DNA. The Salmonella test can play a central role in a program of prevention: to identify mutagenic chemicals in the environment (all indications are there are many) and to aid in the development of non-mutagenic products to prevent future human exposure.
Relativized problems with abelian phase group in topological dynamics
Authors: McMahon Douglas
Published: May 2006

Let (
X, T
) be the equicontinuous minimal transformation group with
X
= π
∞
Z
2
, the Cantor group, and
S
= [unk]
∞
Z
2
endowed with the discrete topology acting on
X
by right multiplication. For any countable group
T
we construct a function
F:X
×
S
→
T
such that if (
Y, T
) is a minimal transformation group, then (
X
×
Y, S
) is a minimal transformation group with the action defined by (
x, y
)
s
= [
xs, yF(x, s)
]. If (
W, T
) is a minimal transformation group and ϕ:(
Y, T
) → (
W, T
) is a homomorphism, then identity
x
ϕ:(
X
×
Y, S
) → (
X
×
W, S
) is a homomorphism and has many of the same properties that ϕ has. For this reason, one may assume that the phase group is abelian (or
S
) without loss of generality for many relativized problems in topological dynamics.
Double-stranded RNA in chromatin transcripts formed by exogenous RNA polymerase.
Authors: Pays E
Published: May 2006

RNA transcribed in vitro at low ionic strength, from either rat liver chromatin or DNA, contains a significant amount of structure resistant to RNase in high salt buffer. This is observed with rat liver (form B polymerase) as well as with Escherichia coli RNA polymerase (RNA nucleotidyltransferase; nucleoside triphosphate: RNA nucleotidyltransferase; EC 2.7.7.6). Treatment with RNases specific for either double-stranded or hybrid RNA indicates that resistance to RNase is due to the presence of double-stranded RNA sequences. Denaturation kinetics in the presence or absence of RNase suggest that these sequences are formed by intramolecular base pairing. Their mean length is about 20 to 30 nucleotides, but 15-20% are more than 100 nucleotides long. They contain 60-65% G-C base pairs. The proportion of double-stranded segments is higher in chromatin transcripts than in DNA-templated RNA, and is higher with homologous RNA polymerase than with the bacterial enzyme. On the other hand, chromatin endogenous RNA polymerase, which is unable to initiate transcription, does not synthesize double-stranded RNA. The problem of the location of these sequences is discussed; preliminary results suggest that the 5' end of the RNA transcripts could be enriched in complementary sequences.
The inverse problem for convex bodies
Authors: Majda Andrew
Published: May 2006

A completely rigorous study of the high frequency asymptotics for the scattering matrix in the exterior of convex bodies is developed. These results are then applied to a variety of inverse problems for convex bodies.
Mapping of the three species of polyoma mRNA.
Authors: Türler H , Salomon C , Allet B , Weil R
Published: May 2006

The polyoma mRNA's present in the cytoplasm of primary cultures of mouse kidney cells during lytic infection were characterized by sedimentation velocity analysis and by hybridization to polyoma DNA fragments generated by a specific endonuclease of Hemophilus parainfluenzae (Hpa II).
In vitro transcription of chromatin in the presence of a mercurated nucleotide.
Authors: Crouse G F , Fodor J B , Doty P
Published: May 2006

Mercurated uridine triphosphate has been used to label transcripts of chicken reticulocyte chromatin made with Escherichia coli RNA polymerase. The mercury-labeled RNA product can be completely separated from endogenous RNA sequences in the chromatin by passage through a sulfhydryl Sepharose column. Globin cDNA hybridization to the transcript shows that only 2.6 x 10-5 of the transcript is globin RNA. In contrast to this result, erythrocte chromatin transcript contains less than one tenth as many globin RNA sequences.
Structural and kinetic studies of lasalocid A (X537A) and its silver, sodium, and barium salts in nonpolar solvents.
Authors: Patel D J , Shen C
Published: May 2006

The ionophore lasalocid A (X537A) and its metal salts have been investigated by high resolution (270 MHz and 360 MHz) proton nuclear magnetic resonance spectroscopy to obtain structural and kinetic information in nonpolar solution. The proton resonances were assigned from double resonance studies on lasalocid A and on its salts, homologs, isomers, and chemically modified derivatives. Studies of proton and carbon longitudinal relaxation time suggest that lasalocid A exists as a monomer, whereas the sodium and barium salts exist as dimers in nonpolar solvents. A study of the magnitude of the vicinal proton coupling constants and the chemical shifts and linewidths of the hydroxyl resonances suggest that the backbone conformation and intramolecular hydrogen bonds are similar for lasalocid A and its sodium and barium salts in nonpolar solvents. Nuclear magnetic resonance studies on the role of bound solvent molecules suggest a tightly bound water molecule in the barium complex dimer (crystallized from water-ethanol) and a weakly bound ethanol molecule in the lasalocid A monomer (crystallized from ethanol) in cyclohexane. The selective changes in proton chemical shift on complexation [where the polar faces of two lasalocid anions coordinate the metal cation(s) in nonpolar solvents have been analyzed in terms of the proximity of the resonances to the cation, their linkage to the coordinating oxygen atoms, and the magnetic anisotropy effects of the polar groups of one ligand on the resonances of its partner in the dimer. The nuclear magnetic resonance studies in solution are compared with earlier observations on lasalocid A and its salts in the crystalline state. Thus, the short Ag-C5 distance in the crystal structure of silver complex dimer is also observed in the solution structure. The kinetic parameters associated with the exchange between lasalocid A and its barium complex in chloroform have been measured from an analysis of the resonance line shapes as a function of temperature.
On vector-valued asymptotic martingales
Authors: Bellow Alexandra
Published: May 2006

In contrast to the vector-valued martingale which converges strongly almost everywhere if and only if the Banach space
E
has the Radon-Nikodym property, the vector-valued asymptotic martingale converges strongly almost everywhere if and only if
E
is of finite dimension.
Classification of irreducible tempered representations of semisimple Lie groups
Authors: Knapp A. W. , Zuckerman Gregg
Published: May 2006

For each connected real semisimple matrix group, one obtains a constructive list of the irreducible tempered unitary representations and their characters. These irreducible representations all turn out to be instances of a more general kind of representation, here called basic. The result completes Langland's classification of all irreducible admissible representations for such groups. Since not all basic representations are irreducible, a study is made of character identities relating different basic representations and of the commuting algebra for each basic representation.
Isolation of an inhibitor of DNA synthesis specific for normal and malignant mammary cells.
Authors: Gonzalez R , Verly W G
Published: May 2006

A small-molecular-weight inhibitor of DNA synthesis, specific for normal and malignant mammary cells but devoid of species-specificity, has been isolated from bovine mammary glands. This factor has very little effect on RNA metabolism.
Physical studies of denatured tRNA2Glu from Escherichia coli.
Authors: Bina-Stein M , Crothers D M , Hilbers C W , Shulman R G
Published: May 2006

We have examined the 270 MHz nuclear magnetic resonance spectrum and relaxation kinetic behavior of tRNA2Glu (E. coli) in the absence of Mg++, a condition which produces an inactive form of this tRNA. The results show that the denatured form has about five fewer proton resonances in the region from -12 to -15 ppm. Relaxation kinetic measurements reveal that the denatured conformer contains three separately melting helices. The results support a model in which the tertiary structure and dihydrouridine helix characteristic of the native form are unfolded in the denatured state, and are replaced by an altered tertiary structure. The acceptor stem, anticodon, and TpsiC helices are intact in this model for the denatured conformation. The optical changes that accompany melting of the denatured tertiary structure are faster than 10 musec.
Detergent-soluble HLA antigens contain a hydrophilic region at the COOH-terminus and a penultimate hydrophobic region.
Authors: Springer T A , Strominger J L
Published: May 2006

Purified, detergent-soluble HLA antigens (p44,12) are composed of a glycoprotein of molecular weight 44,000 (p44) and a peptide of molecular weight 12,000 (p12), beta2-microglobulin. Upon digestion with papain, p44,12 is converted to p39,12, then to p34,12, which retains antigenic activity. The NH2-terminal amino acid sequences of p34 and p44 are identical. p44, p39, and p34 were purified, and comparison of their amino acid compositions showed that the COOH-terminal peptide removed by the first papain cleavage is hydrophilic and contains cysteine that can be alkylated after mild reduction. The penultimate COOH-terminal peptide removed by the second papain cleavage is hydrophobic, and presumably anchors HLA antigens to the membrane. This correlates with the observation that p44,12 and p39,12 bind detergent, while p34,12 does not. The orientation and integration of HLA antigens in the lymphocyte membrane were thus defined, and the structure suggests that HLA antigens span the plasma membrane.
In vitro system for induction of delayed early RNA of bacteriophage T4.
Authors: Thermes C , Daegelen P , De Franciscis V , Brody E
Published: May 2006

Concentrated lysates of Escherichia coli that had been infected with bacteriophage T4 in the presence of chloramphenicol show the same restriction of transcription in vitro as is found in vivo. Restricted lysates can be complemented with lysates from infected cells to induce production of delayed early RNA. Complementation takes place between the RNA polymerase of the restricted lysate and the DNA of the unrestricted lysate. We present evidence that delayed early RNA in these lysates is initiated at quasi-late (middle) promoters, and that such recognition is related to changes in the state of the template DNA.
Hormonal control of pyruvate kinase activity and of gluconeogenesis in isolated hepatocytes.
Authors: Feliú J E , Hue L , Hers H G
Published: May 2006

Treatment of isolated rat hepatocytes with saturating concentrations of glucagon caused several modifications properties of pyruvate kinase (ATP:pyruvate 2-O-phosphotransferase, EC 2.7.1.40): S0.5 (substrate concentration at half maximum velocity) for phosphoenolpyruvate was about doubled, whereas Vmax was not changed; the activity measured at 0.15 mM phosphoenolpyruvate (physiological concentration) was reduced 65-80%; and there was also an increase in the Hill coefficient and in the affinity of the enzyme for the inhibitors Mg-ATP and alanine. Glucagon, 3':5'-cyclic AMP, and epinephrine caused an inactivation of pyruvate kinase together with a sitmulation of gluconeogenesis. Insulin (10 nM) antagonized the effect of suboptimal doses of glucagon or cyclic AMP and of even maximal doses of epinephrine, on both pyruvate kinase activity and on gluconeogenesis. These observations can be explained by a phosphorylation of pyruvate kinase by cyclic-AMP-dependent protein kinase, as described by Ljungström et al. [(1974) Biochim. Biophys. Acta 358, 289-298] in a reconstructed system. They offer a molecular explanation for the hormonal control of gluconeogenesis. Glucose caused an inhibition of gluconeogenesis with no corresponding change in pyruvate kinase activity.
Inhibition of erythrocyte phosphate transport by high pressures.
Authors: Murphy R B , Libby W F
Published: May 2006

Pressures of 200-1000 atmospheres (20-100 MPa) are found to decrease significantly the amount of phosphate (H32PO4-2)transported into the rabbit erythrocyte under otherwise physiological conditions. Such compression does not cause irreversible morphological changes or result in membrane disruption. The findings are interpreted in terms of a lipid phase transition induced by the high pressure, which is propagated to the associated phosphate transport system by a physical mechanism.
Charge pair model of bioenergetics: Energy transfer
Authors: Kemeny Gabor , Mahanti S. D.
Published: May 2006

The electron tunnelling distance between redox enzymes is estimated. The energy transfer mechanism between a pair of charges is described. The dielectric degrees of freedom are incorporated into the electron transfer rate formula.
Magnetic circular dichroism of molecules in dense media: Spin-forbidden transitions of carbonyl molecules
Authors: Yoon Y. H. , Lee S. T. , Lin S. H. , Eyring H.
Published: May 2006

The purpose of this paper has been to calculate the magnetic rotational strength of the spin-forbidden
1
A
1
→
3
A
2
transition of the carbonyl group. For this purpose, simple molecular orbitals have been used and only one-center integrals have been considered. The calculated results have been compared with the experimental measurements.
Ultraviolet photoelectron studies of biological purines: the valence electronic structure of adenine.
Authors: Peng S , Padva A , LeBreton P R
Published: May 2006

The UV photoelectron spectra of adenine, 9-methyladenine, and 6-methylaminopurine contain highly resolved bands arising from the six highest occupied molecular orbitals. The spectra have been analyzed using UV absorption data, photoelectron data from previous studies of heterocyclic compounds, and results from both semi-empirical and ab initio molecular orbital calculations. The analysis indicates that the first, third, and fifth photoelectron bands in adenine and the two methyl substituted derivatives arise from pi orbitals. The second, fourth, and sixth bands arise from nitrogen atom lone-pair orbitals. Compared to adenine, the six uppermost orbitals of 9-methyladenine and 6-methylaminopurine have lower ionization potentials. This destabilization of the valence electrons is expected to play an important role in causing the increase in base stacking forces observed in methyl substituted adenines.
Fossil microorganisms from the approximately 2800 to 2500 million-year-old Bulawayan stromatolite: Application of ultramicrochemical analyses
Authors: Nagy Lois Anne , Zumberge John E.
Published: May 2006

Microfossils, probably representing members of Precambrian photosynthetic communities of bacteria and blue-green algae, have been found in the approximately 2800-2500 million-year-old Bulawayan stromatolites from Rhodesia. Several populations of coccoid and elongate microfossils have been observed in the dark, carbon-rich stromatolite laminae. Some of these elongate forms are morphologically similar to modern bacterial spores. These microfossils were studied in petrographic thin sections and identified by combined scanning electron microscopy-electron microprobe and by analyses of energy dispersive spectra of individual microfossils. The microfossils contain 1-20% organic carbon; some morphotypes contain traces of sulfur and one other, traces of phosphorus. The polymeric nature of the organic carbon was established by analyzing aggregates of microfossils at elevated temperatures in the solid inlet system of an organic mass spectrometer. The coccoid microfossils range in size from 1.2 to 4.3 μm, the elongate microfossils are from 2.4 to 9.8 μm. They are mineralized with dolomite, embedded in a calcite matrix, and are shown to be both indigenous and syngenous with the rock. Identical microfossils also containing organic carbon but mineralized with quartz have been observed in the stromatolites from Belingwe which are part of the Bulawayan Group from Rhodesia. Caution must be used in the interpretation of what these forms are because of their great age and relatively simple morphologies. However, based on morphology and chemical analyses, they represent fossilized bacteria, blue-green algae, or, most likely, both.
Adenosine 3':5'-cyclic monophosphate deficiency in Neurospora crassa.
Authors: Scott W A
Published: May 2006

Depending on growth conditions, the adenosine 3':5'-cyclic monophosphate (cyclic AMP) levels of the fr mutant, a morphologically aberrant strain of Neurospora crassa, are reduced 2- to 5-fold. By taking advantage of the differences in phenotype of fr in liquid and agar cultures and the positive response of fr grown on solid support to exogenous theophylline, a relationship between the degree of morphological abnormality and intracellular cyclic AMP levels of the mutant is observed. Progressive restoration of the fr phenotype toward a normal state is paralleled by increases in cyclic nucleotide content. Striking differences in the sedimentation and thermal characteristics of the fr and wild-type adenylate cyclases [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] are observed. Approximately 50% of the normal activity sediments at 105,000 X g compared to 5% of the mutant enzyme. In addition, the overall stability of the fr adenylate cyclase is significantly decreased and its rate of inactivation at 37 degrees in the absence of substrate is 10-fold greater than the wild-type adenylate cyclase. Arrhenius plots also indicated that the Q10 (increase in rate per 10 degrees temperature increase) and the temperature of maximal activity of the fr enzyme are reduced. Supplementation of fr agar cultures with linolenic acid results in an elevated cyclic AMP content and a wild-type-like morphology similar to that obtained with inhibitors of phosphodiesterase (3':5'-cyclic AMP 5'-nucleotidohydrolase, EC 3.1.4.17). An increased thermostability of the fr adenylate cyclase occurs on linolenate enrichment of the mutant. It is concluded that the cyclic AMP deficiency is at least partially responsible for the fr phenotype and that this reduction results from a membrane defect that affects adenylate cyclase function.
A gene of bacteriophage T4 whose product prevents true late transcription on cytosine-containing T4 DNA.
Authors: Snyder L , Gold L , Kutter E
Published: May 2006

T-even coliphages have 5-hydroxymethylcytosine in their DNA instead of cytosine. In some T4 mutants, the replicated DNA contains cytosine, but then no late gene products are made. We show that the inability to make late gene products with cytosine-containing T4 DNA is due to a T4 gene products. This gene product, while probably nonessential under normal conditions, interacts with an essential part of the transcription apparatus. Mutations in this gene allow viable T4 particles to be made whose DNA has been substituted almost 100% with cytosine.
Regulation of tubulin synthesis in islets of Langerhans.
Authors: Pipeleers D G , Pipeleers-Marichal M A , Kipnis D M
Published: May 2006

Tubulin represents a major protein in rat pancreatic islets, which averages 0.5% of the total protein content and 6% of the noninsulin protein synthesized under basal metabolic conditions. Glucose increases the synthesis of tubulin twofold to threefold. Tubulin synthesis is also stimulated by adenosine 3':5'-cyclic monophosphate in both the absence and presence of glucose; this effect of adenosine 3':5'-cyclic monophosphate occurs preferential to noninsulin protein synthesis at physiological glucose concentrations. Tubulin synthesis was decreased more than 75% by fasting, an effect prevented by maintaining animals on glucose exclusively. The fasting-induced reduction in tubulin synthesis is corrected in vitro by increasing adenosine 3':5'-cyclic monophosphate levels. These findings parallel changes previously reported in insulin release and suggest that physiological agents can exert their insulin secretory action through an effect upon the rate of tubulin synthesis.
Anaerobic growth of a Rhodopseudomonas species in the dark with carbon monoxide as sole carbon and energy substrate.
Authors: Uffen R L
Published: May 2006

A species of Rhodopseudomonas that grows under strict anaerobic conditions in the dark and requires CO was isolated from lake and pond sediments. Although anaerobic growth in the dark occurs in a chemically defined mineral medium with CO as the only carbon and energy source, growth is stimulated by adding trypticase. Under these conditions, cells exhibit a generation time of 6.7 hr and reach a final concentration of 1 to 3 X 10(9) cells per ml of liquid medium. Resting suspensions of CO-grown cells metabolize about 6.7 mumol of CO per mg of protein in 1 hr and produce equimolar amounts of CO2 and H2 according to the equation CO + H2O leads to CO2 + H2. As predicted by this equation, when cells were suspended in tritium-labeled water containing potassium phosphate buffer at pH 7.0 and incubated with pure CO, 3H2 gas was produced at linear rate with a constant specific activity.
Mutational analysis of developmental control in Caulobacter crescentus.
Authors: Osley M A , Newton A
Published: May 2006

The relationship between the cell cycle and control of development has been studied by a genetic analysis of Caulobacter crescentus. The behavior of conditional cell division mutants showed that cell cycle events, such as DNA replication and cell division, are organized into a dependent pathway(s), i.e., later steps cannot preceed until earlier ones are completed. The ability of these strains to develop normally under nonpermissive conditions suggested that flagellin synthesis and stalk formation are dependent on the completion of different cell-cycle steps: the periodicity of flagellin synthesis is achieved by coupling it to either DNA chain elongation or completion, and stalk formation is dependent on a later step in the cell-division pathway. These developmental events are not themselves required for cell division, however.
Inside-out model for self-assembly of tobacco mosaic virus.
Authors: Lebeurier G , Nicolaieff A , Richards K E
Published: May 2006

Incompletely reconstituted particles of tobacco mosaic virus treated with moderate concentrations of dimethylsulfoxide prior to electron microscopy have two visible tails of unencapsidated RNA, a long one and a short one. The short tail has a constant length of 720 +/- 80 nucleotides in incomplete particles of diverse size and probably corresponds to the 3'OH end of the RNA. The length of the long 5' tail is inversely related to the length of the unfinished rod. Surprisingly, both tails appear to protrude from the same end of the particle. These observations suggest that the strand of RNA coming out of one end of the particle loops back along the length of the rod so as to appear at the opposite end. The "looped-back" tail almost certainly passes down the empty central channel of the incomplete rod. The findings are compatible with a model of tobacco mosaic virus assembly in which the RNA inserts itself beneath layers of incoming protein from within the central channel.
Antigen-specific nonimmunoglobulin factor that neutralizes xenotropic virus is associated with mouse serum lipoproteins.
Authors: Leong J C , Kane J P , Oleszko O , Levy J A
Published: May 2006

A soluble nonimmunoglobulin factor that specifically neutralizes mouse xenotropic C-type virus is found in normal mouse sera. It is stable from pH 2 to neutrality and resists ether extraction, freezing, or brief heating to 100 degrees. It can be separated from immunoglobulins by ultracentrifugation at a density of 1.21 g/cm3. Neutralizing activity is only found with the serum lipoproteins in the fraction with density less than 1.21 g/cm3.
Cleavage map of linear mouse sarcoma virus DNA.
Authors: Canaani E , Duesberg P , Dina D
Published: May 2006

Proviral DNA transcribed from the RNA of Moloney murine sarcoma virus was isolated from newly infected cells. Three forms of viral DNA were observed: (i) a linear double-stranded form of 3.4 X 10(6) daltons which constituted the major viral DNA species in the cell, and is thought to be a complete transcript (monomer) of viral RNA; (ii) a fast-sedimenting viral DNA bigger than the monomeric unit which can be either integrated provirls or concatamers; and (iii) covalently closed circles of monomer size representing 5% or less of the total viral DNA in the cell. The linear viral DNA was tested for its susceptibility to restriction endonucleases by electrophoretic analysis of the digestion products and their identification by hybridization with viral RNA or cDNA probes. The linear DNA is not cleaved by endonucleases EcoRI and BamHI. It is cleaved into two fragments by endonucleases HindIII and Hae II, and into three fragments by restriction endonuclease HincII. The fragments of the viral DNA added up to approximately 3.4 X 10(6) daltons; this and the uniform size of the linear DNA indicated that the viral DNA has unique ends and a complexity of 3.4 X 10(6) daltons. The different cleavage fragments were ordered with respect to each other and the 3' end of the viral RNA. It was observed that fragments from both ends of the linear DNA can be hybridized to sequence(s) at the 3' end of murine sarcoma virus RNA; this result suggested the possibility that a short redundant sequence exists at both termini of the genome.
Isolation of transcriptionally active chromatin from mammalian nucleoli.
Authors: Bombik B M , Huang C H , Baserga R
Published: May 2006

Nucleoli isolated from HeLa cells are functionally active but contain large amounts of RNA and proteins (RNA/DNA ratio 1:1; protein/DNA ratio 7:1). We have isolated from the nucleolus a DNA-protein complex that has the characteristics of nucleolar chromatin (RNA/DNA ratio less than 0.05:1; protein/DNA ratio 1.7:1). This nucleolar chromatin has most of the transcriptional activity of the intact nucleolus and, as assayed by circular dichroism and dye binding, has largely preserved its structure. The isolation of a transcriptionally active, fragment of chromatin, which constitutes only a small part of the total genome and codes for only one recognizable product, offers several advantages for the study of chromatin structure and function.
Integration of avian sarcoma virus DNA sequences in transformed mammalian cells.
Authors: Collins C J , Parsons J T
Published: May 2006

DNA from six avian sarcoma virus (ASV)-transformed mammalian cell lines was digested with the restriction endonucleases EcoRI, Xho I, or Sal I, fractionated by agarose gel electrophoresis, transferred to nitrocellulose filter strips, and hybridized with specific ASV [32P]cDNA probes. DNA from all of the ASV-transformed cell lines yielded three common virus-specific DNA fragments (2.4, 1.8, and 1.3 X 10(6) daltons) upon cleavage with EcoRI. Xho I appeared to cleave at least once within the integrated provirus and yielded a common fragment of 3.3 X 10(6) daltons as well as a second virus-specific DNA fragment whose size varied from 4.0 to 5.0 X 10(6) daltons in the different transformed cell lines. Sal I did not cleave within the provirus and yielded a single major virus-specific fragment of about 11 X 10(6) daltons in all transformed lines examined. Using specific cDNA probes, we show that the 1.8 X 10(6)-dalton EcoRI fragment contains sequences homologous to the 3' end of the viral RNA as well as to the src region of the viral genome. These studies clearly demonstrate that the same region on the ASV genome is utilized for provirus integration in different ASV-transformed cell lines.
Limited accessibility of chromatin satellite DNA to RNA polymerase from Escherichia coli.
Authors: Gjerset R A , McCarthy B J
Published: May 2006

An attempt was made to elucidate some of the factors influencing the fidelity with which isolated chromatin from mouse L-cells is transcribed by RNA polymerase from Escherichia coli by analyzing the in vitro transcript for the presence of satellite sequences. These sequences are absent from cellular RNA and therefore reflect aberrant transcription. The results indicate that satellite sequences are underrepresented in chromatin transcripts relative to those of DNA. This selectivity is insensitive to many variables in procedures for the isolation and transcription of chromatin. However, lowering the ratio of enzyme to template further reduced the proportion of satellite sequences in the transcript. We conclude that a primary factor influencing the extent of aberrant transcription is the level of enzyme used. Under limiting enzyme conditions, an efficient selection against satellite sequences is observed. However, under conditions of enzyme excess, the enzyme initiates chains at weaker secondary promoters localized in regions of the chromatin containing satellite DNA.
Transcription termination at the trp operon attenuators of Escherichia coli and Salmonella typhimurium: RNA secondary structure and regulation of termination.
Authors: Lee F , Yanofsky C
Published: May 2006

Transcription termination at the attenuators of the trp operons of Escherichia coli and Salmonella typhimurium was studied in vitro using DNA restriction fragments as templates. Readthrough transcription beyond the terminators occurred with 5 and 30% efficiency, respectively, in E. coli and S. typhimurium. This difference is correlated with the stability of proposed secondary structures of the respective trp leader transcripts. Secondary structure analyses of the two leader transcripts revealed a well-conserved pattern of RNA base paring. This and the possibility that trp leader RNA is translated suggest a model for regulation of transcription termination that is based on ribosome movement along the RNA and a shift between alternative RNA base-pairing configuration.
Sequence relationship between long and short repetitive DNA of the rat: a preliminary report.
Authors: Wu J R , Pearson W R , Posakony J W , Bonner J
Published: May 2006

Long and short repetitive sequences of rat DNA can be isolated and characterized. Long [greater than 1.5 kilobases (kb)] sequences can be separated from short (0.2-0.4 kb) sequences by exclusion chromatography after renaturation of 4-kb DNA fragments to a repetitive Cot and digestion with the single-strand-specific S1 nuclease. (Cot is the initial concentration of DNA in mol of nucleotides/liter multiplied by time in sec.) Long repetitive DNA can be driven by an excess of whole rat DNA can also be used to drive tracer quantities of either long (self-renaturation) or short repetitive DNA. Both the extent and the rate of the renaturations are found to be similar, suggesting that long and short DNA fragments share sequences. When long repetitive DNA is used to drive whole DNA tracers of various lengths, a 3.2-kb interspersion period is found. These data are consistent with the concept that short repetitive sequences are present within long repetitive DNA sequences in the rat genome.
Mysterious form of referred sensation in man.
Authors: Richter C P
Published: May 2006

A phenomenon is described in which scratching a small excrescence on the skin on one part of the body is referred to a distant point as a "prick" or a "tingle". "Referral" points are elicited mainly by absent-minded scratching of the skin when attention is not focused on the local sensation produced by the scratch. Location of "referral" points seems to follow definite patterns: in all instances, "referral" points occurred on the same side of the body as the "stimulus" point; and each "referral" point was rostral to its "stimulus" point; and each "stimulus" point was associated with only one "referral" point. "Stimulus" and "referral" points seem to have a fixed relationship. Pathways from a "stimulus" point to a "referral" point are not known at present. Although parallels can be drawn between this phenomenon and Bender's "double simultaneous stimulation" phenomenon, both remain mysteries.
Escherichia coli ribosomal protein S1 has two polynucleotide binding sites.
Authors: Draper D E , Pratt C W , von Hippel P H
Published: May 2006

The interaction of Escherichia coli ribosomal protein S1 with a variety of RNA and DNA oligomers and polymers has been studied, using both a sedimentation technique and the quenching of intrinsic protein fluorescence upon nucleic acid binding to obtain equilibrium binding parameters. Two polynucleotide binding sites have been detected on S1: site I binds either single-stranded DNA or RNA and does not discriminate between adenine- and cytidine-containing polynucleotides, while the II binding is highly specific for RNA over DNA and shows a marked preference for cytidine polynucleotides over the corresponding adenine-containing species. On the basis of the binding properties of S1 to denatured DNA cellulose and poly(rC)-cellulose, it is demonstrated that every S1 molecule carries both a site I and a site II. Some possible implications of these results for mechanisms of protein synthesis and phage Qbeta replication are briefly considered.
Homoserine dehydrogenase: spontaneous reactivation by dissociation of p-mercuribenzoate from an inactive enzyme--p-mercuribenzoate complex.
Authors: Epstein C C , Datta P
Published: May 2006

Incubation of Rhodospirillum rubrum homoserine dehydrogenase (L-homoserine:NAD+ oxidoreductase, EC 1.1.1.3) with p-mercuribenzoate (PMB) in the presence of 0.2 M KCl and 2 mM L-threonine resulted in complete loss of enzyme activity. Upon removal of excess PMB, KCl, and L-threonine, a time-dependent recovery of enzyme activity was observed in 25 mM phosphate/I mM EDTA buffer, pH 7.5. Circular dichroism studies indicated that the transition from inactive to reactivated form of the enzyme was accompanied by a conformational change in the protein. Experiments with [14C]PMB revealed loss of enzyme-bound radioactivity during reactivation. Increase in ionic strength of the phosphate buffer and/or addition of L-threonine, leading to enzyme aggregation, decreased the rate of enzyme reactivation, aggregated enzyme that remained inactive retained [14C]PMB on the enzyme. Sulfhydryl titration of various forms of the enzyme suggested a preferential release of PMB from a sulfhydryl group essential to enzymic activity. We conclude that reactivation of the inactive enzyme is due to dissociation of PMB from an "active-site" sulfhydryl group and that changes in the protein structure influence the rate of dissociation of the enzyme-PMB complex.
Hexamethylene bisacetamide induces morphologic changes and increased synthesis of procollagen in cell line from glioblastoma multiforme.
Authors: Rabson A S , Stern R , Tralka T S , Costa J , Wilczek J
Published: May 2006

Addition to hexamethylene bisacetamide (diacetyldiaminohexane) to cultures of a malignant mesenchymal cell line derived from a human glioblastoma multiforme induces morphological changes and stimulates the synthesis of procollagen. The morphological changes include cell elongation, an increase of extracellular material with staining properties of collagen by light microscopy, and an increase in extracellular 220-A fibrils by electron microscopy. The rate of procollagen synthesis increased as much as 20-fold, and the ratio of type I:type III procollagen changed, with type I becoming the predominant form. The change in type I:type III ratio is similar to that seen in the maturation of normal fetal to adult connective tissue.
Chemical compositions of Magellanic Clouds' HII regions based on photoelectric spectrophotometry
Authors: Aller L. H. , Czyzak S. J. , Keyes C. D.
Published: May 2006

Detailed line intensity measurements secured at Cerro Tololo Interamerican Observatory and corrected for interstellar extinction are presented for 19 HII regions in the Large Magellanic Cloud and 6 in the Small Magellanic Cloud. The elemental abundances derived by simple methods appear to be in good accord with those found by other observers. Detailed discussion is deferred to a later paper.
Characterization of early simian virus 40 transcriptional complexes: late transcription in the absence of detectable DNA replication.
Authors: Ferdinand F J , Brown M , Khoury G
Published: May 2006

Isolation of early viral transcriptional complexes and incorporation in vitro of radiolabeled precursors into nascent RNA has permitted an analysis of early simian virus 40 (SV40) transcription. Under conditions such that viral DNA replication was undetectable, both early and late SV40 RNA were synthesized. This finding provides evidence that viral DNA replication is not an absolute requirement for late transcription and supports earlier observations that late viral RNA is synthesized in SV40-infected nonpermissive mouse cells. The majority of the early viral transcriptional activity can be solubilized, indicating that a substantial portion of this RNA is transcribed from free rather than integrated templates. Sedimentation analysis of the transcriptional complexes resulted in the detection of two separate peaks of activity, suggesting the possibility of two distinct types of early SV40 templates.
A method of computational magnetohydrodynamics defining stable Scyllac equilibria
Authors: Betancourt Octavio , Garabedian Paul
Published: May 2006

A computer code has been developed for the numerical calculation of sharp boundary equilibria of a toroidal plasma with diffuse pressure profile. This generalizes earlier work that was done separately on the sharp boundary and diffuse models, and it allows for large amplitude distortions of the plasma in three-dimensional space. By running the code, equilibria that are stable to the so-called
m
= 1,
k
= 0 mode have been found for Scyllac, which is a high beta toroidal confinement device of very large aspect ratio.
Isolation of the penicillin-binding peptide from D-alanine carboxypeptidase of Bacillus subtilis.
Authors: Georgopapadakou N , Hammarström S , Strominger J L
Published: May 2006

The D-alanine carboxypeptidase of B. subtilis is a membrane-bound enzyme which is inhibited by penicillins and binds them covalently. The enzyme has been labeled with [14C]- or [35S]penicillin. After tryptic or Pronase digestion of the labeled, denatured, reduced, and carboxymethylated enzyme, a radioactive peptide was isolated in each case. The amino acid compositions of these two peptides are reported. The Pronase peptide was a subset of the tryptic peptide. Neither contained a cysteine residue and the only amino acid in the Pronase peptide to which the penicillin could be bound was a serine residue.
Minimal length of the lactose operator sequence for the specific recognition by the lactose repressor.
Authors: Bahl C P , Wu R , Stawinsky J , Narang S A
Published: May 2006

A number of specific duplex DNA sequences which correspond to varying lengths of the lactose operator region have been synthesized by a combination of chemical and enzymatic methods. Repressor binding studies on these synthetic duplex operator molecules show that all the nucleotides essential for full lactose operator-repressor interactions are included in a 17-nucleotide-long duplex DNA that constitutes the minimal recognition sequence for this DNA-protein interaction.