bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of thyrotropin and cholera toxin to probe the mechanism by which interferon initiates its antiviral activity.
Authors: Kohn L D , Friedman R M , Holmes J M , Lee G
Published: May 2006

Thyrotropin (10 muM) inhibited the antiviral activity of interferon. When added after interferon, thyrotropin (TSH) had no effect on antiviral activity. There was also no inhibition of interferon action in cells washed with medium between incubations with TSH and interferon. 125I-Labeled TSH and 125I-labeled cholera toxin could bind to preparations of mouse L-cell plasma membranes. The binding was specific in that it was prevented by unlabeled thyrotropin or cholera toxin, but not by insulin, glucagon, prolactin, growth hormone, human chorionic gonadotropin, or luteinizing hormone. Mouse interferon inhibited 125I-labeled TSH binding to L-cell plasma membranes. The effect of mouse interferon on 125I-labeled cholera toxon binding was more complex, inhibition occurring only after an initial enhancement at low interferon concentrations. A 10-fold higher concentration of interferon was required to inhibit 125I-labeled TSH binding. Mouse interferon was also able to displace bound 125I-labeled TSH, but not bound 125I-labeled cholera toxin. The interferon interaction with cell membranes was temperature-sensitive. Human interferon could induce changes in binding of 125I-labeled TSH and 125I-labeled cholera toxin to mouse L-cell plasma membranes similar to those induced by mouse interferon. Mouse interferon induced similar changes in plasma membranes of human KB-3 cells, which are insensitive to both human and mouse interferons. In view of these results, the species specificity of interferons does not appear to reside solely at the point of the initial interaction with their binding sites.
Nucleotide sequences in mouse DNA and RNA specific for Moloney sarcoma virus.
Authors: Frankel A E , Fischinger P J
Published: May 2006

Complementary DNA (cDNA) synthesized by Moloney murine sarcoma virus (M-MSV) was separated into two parts, the first, termed MSV-specific cDNA, composed of nucleotide sequences found only in M-MSV viral RNA, and the second, termed MSV-MuLV common cDNA, composed of nucleotide sequences that were found in both M-MSV and murine leukemia virus (MuLV) VIRAL RNAs. RNA complementary to the MSV-specific cDNA was not found in several other MSV isolates, nor in ecotropic MuLV, mouse mammary tumor virus, or several murine xenotropic oncoviruses. Cellular DNA of several species was examined for the presence of nucleotide sequences complementary to MSV-specific cDNA. Cells transformed by M-MSV did contain MSV-specific cDNA in their DNA. Normal mouse cell DNA apparently contained the majority of MSV-specific nucleotide sequences. Cellular DNA of related species contained proportionally less MSV-specific cDNA. Hybrids of MSV-spedivic cDNA and cellular DNA of related species melted at lower temperatures than hybrids of MSV-specific cDNA and mouse cellular DNA. RNA from normal mouse adult or embryonic cells did not contain detectable nucleotide sequences complementary to MSV-specific cDNA. Transformation of cells with M-msv resulted in transcription of RNA hybridizing with MSV-specific cDNA. Methylcholanthrene-induced mouse sarcomas and cell lines derived from them did not contain RNA complementary to MSV-specific cDNA. Mouse cell lines transformed with avian sarcoma virus or Kirsten MSV-specific cDNA. RNA homologous to MSV-specific nucleotide sequences is measurably present only in cells transformed by M-MSV and not in cells transformed by other biological or chemical agents that also cause sarcomas.
Multiple factor analysis of the action of local anesthetics.
Authors: Lin H C , Ueda I , Eyring H
Published: May 2006

The pH jump data of Bianchi and Strobel [(1968) Trans. N.Y. Acad. Sci. Ser. II, 30, 1082-1092] on desheathed frog sciatic nerve are fitted to rate equations. A general quantitation of synergism, summation, and antagonism of anesthetics and of excitation is given.
Biochemical construction of specific chimeric plasmids from ColE1 DNA and unfractionated Escherichia coli DNA.
Authors: Collins C J , Jackson D A , DeVries A J
Published: May 2006

A series of chimeric plasmids was constructed using colicinigenic factor E1 (ColE1) DNA as the replicon and DNA fragments carrying the galactose or tryptophan operons from E. coli. Restriction endonuclease EcoRI digests of ColE1 DNA and various DNAs containing the trp or gal operons were joined by T4 polynucleotide ligase [polynucleotide synthetase (ATP), poly(deoxyribonucleotide):poly(deoxyribonucleotide) ligase (AMP-forming), EC 6.5.1.1]. Chimeric plasmids carrying the desired genes were selected after transformation of Trp- or Gal- cells with ligated DNA. By using this method, we constructed ColE1-gal and ColE1-trp chimeric plasmids in which the source of the bacterial gal and trp operons was an unfractionated EcoRI digest of total E. coli DNA. The frequency of recovery of such chimeric plasmids is 10 to 20 colonies per mug of ligated DNA used in the transformation step. The method utilized in this report for constructing specific chimeric plasmids from total E. coli DNA is very simple. It requires only endonuclease R-EcoRI and T4 polynucleotide ligase, both of which are commercially available. The yield of transformants suggests that this method will be useful for cloning and amplifying a wide variety of functionally defined genes from E. coli and other prokaryotic organisms.
Tubulin requires tau for growth onto microtubule initiating sites.
Authors: Witman G B , Cleveland D W , Weingarten M D , Kirschner M W
Published: May 2006

Tubulin purified by phosphocellulose chromatography and free of accessory proteins will not form microtubules in the absence or presence of microtubule initiating sites (flagellar microtubules). The capacity for growth onto pre-existing "seeds" can be restored by the addition of small quantities of partially purified tau protein. Larger quantities restore the capacity for spontaneous assembly. These results suggest that tubulin requires tau for both initiation and growth of microtubules and that tau is incorporated into the microtubule throughout its length.
Volume changes in binding of ligands to methemoglobin and metmyoglobin.
Authors: Ogunmola G B , Kauzmann W , Zipp A
Published: May 2006

The volume changes for the binding of various ligands to metmyoglobin and methemoglobin have been determined from the effect of pressure on the binding constants (for metmyoglobin) and by direct dilatometry (for methemoglobin). The volume changes associated with the binding of cyanide and azide ions to methemoglobin are pH-dependent. The volume change for the binding reaction is evidently affected by the same subtle structural variations that have been judged to be present from the variation with pH of enthalpy and entropy for the binding reactions in these proteins. Hydration changes and spin state changes which have been postulated to be linked with structural variations in these proteins must be pH-dependent.
On completeness of the Bergman metric and its subordinate metric
Authors: Hahn Kyong T.
Published: May 2006

It is proved that on any bounded domain in the complex Euclidean space

C
n

the Bergman metric is always greater than or equal to the Carathéodory distance. This leads to a number of interesting consequences. Here two such consequences are given. (
i
) The Bergman metric is complete whenever the Carathéodory distance is complete on a bounded domain. (
ii
) The Weil-Petersson metric is not uniformly equivalent to the Bergman metric in the Teichmüller space
T
(
g
) of any Riemann surface of genus
g
≥ 2.
Endonuclease II, apurinic acid endonuclease, and exonuclease III.
Authors: Kirtikar D M , Cathcart G R , Goldthwait D A
Published: May 2006

An endonuclease of Escherichia coli active on a DNA treated with methylmethane sulfonate has been separated from an endonuclease active on depurinated sites. The former enzyme is disignated here as endonuclease II, while the latter enzyme is designated as apurinic acid endonuclease. Endonuclease II is also active on DNA treated with methylnitrosourea, 7-bromomethyl-12-methylbenz[a]anthracene, and gamma-irradiation. A third fraction which contains activities for both depurinated and alkylated sites needs further study. Endonuclease II, molecular weight 33,000, has been purified 12,500-fold and does not have exonuclease III activity. Apurinic acid endonuclease, molecular weight 31,500, has been purified 11,000-fold and does not have exonuclease III activity. Exonuclease III, molecular weight 26,000, has been purified 2300-fold and does not have endonucleolytic activity at depurinated reduced sites or at alkylated sites in DNA. Therefore, these are three separate proteins. Exonuclease III can produce, presumably by its exonucleolytic activity, double-strand breaks in heavily alkylated DNA under conditions where it does not make single-strand endonucleolytic breaks at either depurinated-reduced or alkylated sites.
Amino-terminal sequences of two polypeptides from human serum with nonsuppressible insulin-like and cell-growth-promoting activities: evidence for structural homology with insulin B chain.
Authors: Rinderknecht E , Humbel R E
Published: May 2006

The amino-terminal sequences of two polypeptides with nonsuppressible insulin-like and cell-growth-promoting activities (NSILA I and II), isolated from human serum, were determined. Of the first 31 residues, 22 are identical in NSILA I and II. Moreover, a striking structural similarity was found between NSILA and insulin B chain: 47 and 57% of residues 1-30 in NSILA I are identical to those in insulin B chain from man and tuna fish, respectively. This high degree of sequence identity is presented as evidence for homology and thus for a common evolutionary origin of insulin and NSILA. Based on these results and on these results and on biological properties of NSILA described earlier, a new designation for NSILA is proposed: insulin-like growth factor (IGF).
Synthesis of type II collagen in vitro by embryonic chick neural retina tissue.
Authors: Smith G N , Linsenmayer T F , Newsome D A
Published: May 2006

Collagen produced by chick neural retina tissue in vitro has the properties of type II collagen. Isolated neural retina tissue from stage 29-32 chick embryos incorporated [14C]glycine and [3H]proline into collagen consisting of alpha1 chains and a higher molecular weight species. The peptides produced by cyanogen bromide digestion of the collagen are identical to those from authentic type II collagen from cartilage in charge properties, as determined by carboxymethyl-cellulose chromatography, and size distribution, as determined by sodium dodecyl sulfate-acrylamide gel electrophoresis.
Steady-state kinetic formalism applied to multienzyme complexes, oxidative phosphorylation, and interacting enzymes.
Authors: Hill T L
Published: May 2006

A kinetic formalism, quite generally valid for free energy transducing, steady-state, macromolecular systems in biology, is applied here to multienzyme complexes, oxidative phosphorylation, and interacting enzymes. Systems of this type, comprising several interacting subunits, each with its own discrete set of states, present no new features in principle. Hence, they may be handled by the earlier kinetic formalism without modification. However, the kinetic diagram can become quite complicated because the state of each subunit (enzyme) must be specified in order to specify any one state of the system (complex) as a whole. Cycles, forces, fluxes, free energy levels, and state probabilities are considered.
Determination of molecular weight of the protein moiety in protein-detergent complexes without direct knowledge of detergent binding.
Authors: Reynolds J A , Tanford C
Published: May 2006

Sedimentation equilibrium measurements can be used to determine the molecular weight of the protein moiety of a protein-detergent complex without prior knowledge of detergent binding. The procedure is to adjust the solvent density by addition of D2O so as to blank out the contribution of bound detergent to the sedimentation potential. An approximate measure of detergent binding can be obtained from the effect of solvent density on the sedimentation result. The procedure is also applicable to protein-lipid complexes. It can be used for complexes containing both lipid and detergent if the lipid content is known. The use of the method is demonstrated by experimental data for the AI polypeptide of serum high density lipoprotein, in separate complexes with nonionic detergents and with a phospholipid.
Rate of quaternary structure change in hemoglobin measured by modulated excitation.
Authors: Ferrone F A , Hopfield J J
Published: May 2006

Using a novel technique of modulated photo-dissociation of carbon monoxide from hemoglobin, we have obtained the rates for conversion between the two quaternary states, R, and T, at 3-fold ligation. Our measurements at pH 7 and 22 degrees give rates of 780 +/- 40 sec-1 for going from R to T, and 2500 +/- 200 sec-1 from T to R. This yields an equilibrium constant of 0.31 +/- 0.04, which is in good agreement with previous estimates. The degree of agreement between this equilibrium constant and that predicted from the allosteric model provides a new, quantitative test of the allosteric description. A sequential model for the change in structure was found incompatible with the data, even if kinetic subunit inequivalence was assumed. The technique described here is quite general and can be used as long as the system under investigation can be repetitively excited in a regime in which it responds linearly to the excitation.
Hypophosphatemia: mouse model for human familial hypophosphatemic (vitamin D-resistant) rickets.
Authors: Eicher E M , Southard J L , Scriver C R , Glorieux F H
Published: May 2006

A new dominant mutation in the laboratory mouse, hypophosphatemia (gene symbol Hyp), has been identified. The Hyp gene is located on the X-chromosome and maps at the distal end. Mutant mice are characterized by hypophosphatemia, bone changes resembling rickets, diminished bone ash, dwarfism, and high fractional excretion of phosphate anion (low net tubular reabsorption). Phosphate supplementation of the diet from wearning prevents the appearance of severe skeletal abnormalities. The hypophosphatemic male mouse resembles human males with X-linked hypophosphatemia and the Hyp gene is presemably homologous with the X-linked human gene. The mouse model should facilitate study of the defect in transport of plasma inorganic phosphate anion.
On the lifetime-width relation for a decaying state and the uncertainty principle
Authors: Bauer M. , Mello P. A.
Published: May 2006

A new formulation of the uncertainty relation of position and momentum, and of energy and time, is presented. The connection between the lifetime of excited states and the energy width of these states, which does not follow from the usual uncertainty relation, is shown to be a consequence of the expression here derived.
A hepatic receptor of avian origin capable of binding specifically modified glycoproteins.
Authors: Lunney J , Ashwell G
Published: May 2006

Evidence is reported to support the following conclusions: (i) The presence of a specific hepatic receptor capable of recognizing and binding galactose-terminated glycoproteins is responsible for maintaining near zero levels of circulating asialoglycoproteins in mammalian serum. (ii) The absence of this galactose-specific binding protein in avian, and presumably reptilian, liver is correlated with high levels of circulating asialoglycoproteins in the serum of these species. (iii) The evolutionary significance of these observations is reinforced by the recognition of an avian hepatic binding protein specific for terminal, N-acetyl-glucosamine residues on glycoproteins.
Synthesis of Rauscher murine leukemia virus-specific polypeptides in vitro.
Authors: Gielkens A L , Van Zaane D , Bloemers H P , Bloemendal H
Published: May 2006

The biosynthesis of specific polypeptides directed by purified viral messenger RNA from JLS-V9 cells infected with Rauscher leukemia virus has been studied in a rabbit reticulocyte lysate. The 35S viral mRNA gives rise to two major products of 65,000 and 72,000 molecular weight. The synthesis of specific polypeptides was also investigated in lysates derived from infected cells. The main products were polypeptides with molecular weights of 65,000, 76,000, and 82,000, and were preferentially made in association with membranes. The relative content of the virus-specific polypeptide of 65,000 molecular weight, synthesized in a cell-free system supplemented with purified polyribosomes, is considerably higher for membrane-bound polyribosomes.
Studies on nucleic acid reassociation kinetics: empirical equations describing DNA reassociation.
Authors: Britten R J , Davidson E H
Published: May 2006

The rate of appearance of duplex DNA renaturation, measured with single strand specific nuclease, deviates significantly from a second order reaction. Measurements reported in paper I of this series indicate an inhibition in the rate of reassociation of single strand tails on partially reassociated molecules by a factor of at least two. Equations are derived that describe the observed form of reassociation kinetics as measured with hydroxyapatite and with single strand specific nuclease. The free parameter that describes the extent of inhibition of nucleation with single strand tails in these equations has been evaluated by least squares methods and agrees with the experimentally measured value.
Zein synthesis in maize endosperm by polyribosomes attached to protein bodies.
Authors: Burr B , Burr F A
Published: May 2006

The protein bodies in maize endosperm are the sites of zein deposition. They are single membrane-bound vesicles with polysomes associated with the exterior surface of the membrane. These protein bodies were isolated by sucrose density gradients and characterized by electron microscopy and polyacrylamide gel electrophoresis. Polyribosomes dissociated from the surface of the membrane by detergent treatment were placed into an amino-acid incorporating system. Based on alcohol solubility, amino-acid composition, and molecular weight distribution, the product synthesized appeared to be largely, or entirely, zein. This suggests the existence of components which are specific for the synthesis of zein at the protein body membrane surface.
Increase in type I and type III collagens in human alcoholic liver cirrhosis.
Authors: Rojkind M , Martinez-Palomo A
Published: May 2006

Collagen in bulk was isolated in about 30% yield from the livers of normal human beings and from livers of persons with alcholic cirrhosis. Analyzed chemically and examined by electron microscopy, the collagen in each case was shown to consist of two types identical with, or resembling closely, type I and type III collagens of skin. The collagen from normal liver was predominantly type I, whereas, that from cirrhotic livers consisted or approximately equal amounts of the two types. By chromatography on carboxymethyl-cellulose, the type I collagen from the cirrhotic livers showed one alpha2chain and two alpha1 chains. The alpha1 chains were separable from one another, but gel electrophoretic patterns of peptides obtained from them after treatment with CNBr were almost identical, and resembled the pattern obtained with CNBr peptides of the alpha1 chain of rat skin type I collagen. The increased collagen of both types was responsible in part for the observed distortion of the architecture of the cirrhotic livers associated with increased rigidity of the stroma. The predominance of type III collagen in the areas of collapse of architecture where, as shown by others, few fibroblasts are present, suggests that hepatocytes might have an important function in fibrogenesis during the course of liver cirrhosis.
Inhibition of tumor cell proliferation by dimerized ribonuclease.
Authors: Bartholeyns J , Baudhuin P
Published: May 2006

A cross-linked dimer of pancreatic ribonuclease A (ribonucleate 3'-pyrimidino-olitonucleotidohydrolase, EC 3.1.4.22), at a 10 mg/liter concentration, blocks proliferation of tumor cells. The protein retains this ability after inactivation by iodoacetate. The cytostatic effect of ribonuclease preparations on various cell lines correlates well with their rate of uptake: for example, monomeric ribonuclease A is much less effective and is taken up into the cells 10 t0 15 times more slowly. Cell fractionation studies on hepatoma cells indicate accumulation of the dimer in the lysosomal system. Ribonuclease dimer induces a labilization of the lysosomes when added to cell homogenates, raising the possibility that its antitumoral effect may be mediated by endocytosis and lysosomes.
Theoretical foundations of the chronometric cosmology
Authors: Segal I. E.
Published: May 2006

The derivation of the redshift (
z
)-distance (
r
) relation in the chronometric theory of the Cosmos is amplified. The basic physical quantities are represented by precisely defined self-adjoint operators in global Hilbert spaces. Computations yielding explicit bounds for the deviation of the theoretical prediction from the relation
z
= tan
2
(
r
/2
R
) (where
R
denotes the radius of the universe), earlier derived employing less formal procedures, are carried out for: (
a
) a cut-off plane wave in two dimensions; (
b
) a scalar spherical wave in four dimensions; (
c
) the same as (
b
) with appropriate incorporation of the photon spin. Both this deviation and the (quantum) dispersion in redshift are shown to be unobservably small. A parallel classical treatment is possible and leads to similar results.
Receptor interactions in a signalling system: competition between ribose receptor and galactose receptor in the chemotaxis response.
Authors: Strange P G , Koshland D E
Published: May 2006

Galactose and ribose receptors are shown to compete for a common site by comparing the specificities of the purified receptors with the specificity of the whole organism response. Ribose does not bind to the purified galactose receptor but inhibits the in vivo galactose response. A mutant lacking the ribose receptor shows no inhibition of the galactose response even at very high ribose concentrations. The results can be explained by a mechanism involving (a) a ligand-induced conformational change in the receptor which produces a combining site with affinity for the molecule that serves as a first component of the signalling system and (b) a limited number of such first component molecules that cannot bind both receptors simultaneously. The mechanism may have considerable generality for sensory, hormonal, and transport systems.
Preliminary characterization of the acrasin of the cellular slime mold Polysphondylium violaceum.
Authors: Wurster B , Pan P , Tyan G G , Bonner J T
Published: May 2006

Some species of cellular slime mold do not respond to cyclic AMP as an acrasin, or chemoattractant. In one such species, Polysphondylium violaceum, we have isolated and purified its acrasin and determined some of its chemical properties, which lead us to believe it is a small molecule of less than 1500 daltons. One possibility is that it might be a peptide. The acrasin specifically attracts the amoebae of P. violaceum and P. pallidum and fails to do so for six species of Dictyostelium tested. We also have evidence for a specific acrasinase that inactivates the Polysphondylium acrasin.
Ontogeny of lymphocyte subpopulations in human fetal liver.
Authors: Gupta S , Pahwa R , O'Reilly R , Good R A , Siegal F P
Published: May 2006

Lymphocytes were isolated from five fetal livers (13-17 weeks) and examined for different surface markers. Immunoglobulin M was found on 0.5-4.0% of lymphocytes. No membrane-bound surface IgD, IgA. or IgG was detected. Mouse erythrocyte rosette-forming lymphocytes ranged from 0.5 to 6.0%. Thymus-processed (T) lymphocytes, which were defined as those forming spontaneous rosettes with sheep erythrocytes, as well as lymphocytes with IgG Fc receptors, were present in a small proportion. No complement-receptor-bearing lymphocytes were found in the two cell populations of fetal liver studied. It is evident that during the ontogeny of bone-marrow-derived (B) lymphocytes IgM is the first surface immunoglobulin to appear. Receptors for the binding of mouse erythrocytes are present at the same time as surface IgM. The slight excess of mouse erythrocyte rosette-forming cells over cells having surface immunoglobulin M could mean that IgM appears later than do the receptors for the binding of mouse erythrocytes.
Study design for a hepatitis B vaccine trial.
Authors: Lustbader E D , London W T , Blumberg B S
Published: May 2006

A short-time trial of small sample size for an evaluation of the hepatitis B vaccine is proposed and designed. The vaccine is based on the premise that antibody to the surface antigen of the hepatitis B virus is protective against viral infection. This premise is verified by using the presence of the surface antigen as the marker of infection and comparing infection rates in renal dialysis patients who had naturally acquired antibody to patients without antibody. Patients with antibody have an extremely low risk of infection. The probability of remaining uninfected decreases at an exponential rate for patients without antibody, implying a constant risk of infection at any point in time. The study design described makes use of this time independence and the observed infection rates to formulate a clinical trial which can be accomplished with a relatively small number of patients. This design might be useful if, in preliminary studies, it is shown that the vaccine produces antibody in the patients and that protection against hepatitis B virus would be beneficial to the patients.
On the structure of complete simply-connected Kähler manifolds with nonpositive curvature
Authors: Siu Yum-Tong , Yau Shing-Tung
Published: May 2006

We prove that a complete simply-connected Kähler manifold with nonpositive sectional curvature is biholomorphic to the complex Euclidean space if the curvature is suitably small at infinity.
Reversible in vitro polymerization of tubulin from a cultured cell line (rat glial cell clone C6).
Authors: Wiche G , Cole R D
Published: May 2006

Tubulin from cultures of the rat glial cell clone C6 could be polymerized in vitro into intact microtubules. The polymerization was reversible and spontaneous, i.e., no addition of heterologous nucleation centers was necessary. Two cycles of polymerization/depolymerization yielded tubulin preparations of 95% purity as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Electron microscopy was used to show that the microtubules assembled in vitro by two cycles of polymerization/depolymerization were morphologically intact and temperature sensitive. In contrast, tubulin from neuroblastoma cells, clone Neuro-2A, could not be polymerized in a reversible fashion. The discovery of a cell line from which tubulin can be reversibly polymerized in vitro establishes a model system for studies of cell-cycle- and cell-type-dependent regulatory mechanisms controlling the assembly of microtubules.
Eel esophagus as an osmoregulatory organ.
Authors: Hirano T , Mayer-Gostan N
Published: May 2006

Ion and water permeabilities were measured in the isolated esophagus of the eel (Anguilla anguilla and A. japonica), and compared with those in the stomach and the intestine. The freshwater eel esophagus was impermeable both to Na+ and Cl- ions and to water, whereas permeabilities to the ions increased selectively after seawater adaptation. The ion permeabilities of both the freshwater and the seawater eel stomach were lower than in the seawater eel esophagus, although water permeability was greater than in the esophagus. Sea water enclosed in the lumen was diluted three times more efficiently in the seawater eel esophagus than in the stomach. The intestinal permeabilities were greater than those of the esophagus and the stomach, and increased after seawater adaptation. In the eel, ingested sea water seems to be diluted mainly in the esophagus by passive diffusion of the ions into the blood without addition of water. After further but less important dilution in the stomach with salt removal and with water addition, the water is absorbed by the intestine, following active absorption of the ions. Thus the eel in sea water is able to replace water lost osmotically by drinking hypertonic sea water.
Binding of insulin to isolated nuclei.
Authors: Goldfine I D , Smith G J
Published: May 2006

Specific binding sites for 125I-labeled insulin were detected in purified nuclei isolated from rat liver. Binding was rapid, reversible and directly proportional to the number of nuclei employed. Unlabeled native insulin, at concentrations as low as 1ng/ml, significantly inhibited the binding of labeled hormone, whereas unlabeled proinsulin and desoctapeptide insulin were less potent. In contrast, glucagon, thyrotropin, growth hormone (somatotropin), and prolactin were without effect. Under identical incubation conditions, 125I-labeled glucagon bound to liver plasma membranes 5- to 10-fold more strongly than did insulin; in contrast glucoagon did not bind to liver nuclei. These studies demonstrate the presence of specific binding sites for insulin in purified nuclei isolated from rat liver. In addition, they suggest that the nucleus may be an intracellular site of insulin action.
Characterization of a gamma-carboxyglutamic acid-containing protein from bone.
Authors: Price P A , Otsuka A A , Poser J W , Kristaponis J , Raman N
Published: May 2006

A gamma-carboxyglutamic acid-containing protein has been purified from the calcified tissues of several vertebrates. The presence of three-gamma-carboxyglutamic acid residues in the bovine protein was established by alkaline hydrolysis and amino acid analysis, a method based upon studies with synthetic gamma-carboxyglutamic acid. The identity of gamma-carboxyglutamic acid in the bovine protein was established by mass spectroscopy on the unknown amino acid isolated from alkaline hydrolysates.
Sequential transcription of the genes of vesicular stomatitis virus.
Authors: Abraham G , Banerjee A K
Published: May 2006

Increasing exposure of vesicular stomatitis virus particles to ultraviolet radiation caused differential inhibition of the synthesis in vitro of individual mRNA species which code for the viral structural proteins L, G, M, NS, and N.
Hormone and neurotransmitter receptors in an established vascular endothelial cell line.
Authors: Buonassisi V , Venter J C
Published: May 2006

A cell line from the intima of the rabbit aorta has been established. This cell line exhibits strict contact inhibition, and morphologically resembles intimal endothelial cells. B-type blood group antigens and the presence of fibrinolytic activity also distinguish these cells from smooth muscle cells and from fibroblasts of the aortic wall. Endothelial cells were assayed for changes in levels of adenosine 3':5'-cyclic monophosphate (cAMP) and guanosine 3':5'-cyclic monophosphate (cGMP) in response to a series of vasoactive drugs. Control levels for cAMP and cGMP are 7.01 +/- 0.82 and 1.50 +/- 0.06, respectively (mean +/- SEM). Norepinephrine, acetylcholine, 5-hydroxytryptamine, and phenylephrine increased the levels of both nucleotides significantly. Propranolol (10-5 M) and phentolamine (10-5M) inhibited, respectively, the cAMP and cGMP response to norepinephrine. Angiotensin II and histamine significantly increased cGMP levels but not cAMP levels of the endothelial cells. The cGMP increases with acetylcholine were inhibited by atropine. These results indicate that the established cell line is endothelial in nature and contains cellular receptors to a variety of vasoactive agents.
Fluidity in mitochondrial membranes: thermotropic lateral translational motion of intramembrane particles.
Authors: Höchli M , Hackenbrock C R
Published: May 2006

The fracture faces of frozen rat liver mitochondria reveal that intramembrane particles can be induced to under go long-range lateral translational motion and aggregation, which parallel the appearance of large, particle-free smooth patches in the hydrophobic interior of the two mitochondrial membranes. These lateral separations were observed under conditions that induce thermotropic lipid-lipid phase separations. Low temperature-induced lateral separation occurred between the intramembrane particles (integral proteins) and smooth patches (bilayer lipid) at temperatures between about 10 and -12 degrees in the outer membrane and between about -4 and -12 degrees in the inner, energy transducing membrane.
Helical growth of Bacillus subtilis: a new model of cell growth.
Authors: Mendelson N H
Published: May 2006

A multiple mutant of Bacillus subtilis that grows in an unusual double-helix morphology was studied. Construction of models led to the assumption that cell surface elongation must proceed in a helical path in this mutant. The observation that all newly formed double-helix clones propagated, after spore outgrowth in fluid culture, consisted of closed-circular structures suggested that double-helix structures are tension-registered forms.
Induction of a protein inhibitor to ornithine decarboxylase by the end products of its reaction.
Authors: Heller J S , Fong W F , Canellakis E S
Published: May 2006

Putrescine, the end-product of ornithine decarboxylase (ODC: L-ornithine carboxylyase, EC; 4.1.1.17) action, induces the synthesis of a protein(s), in L1210, neuroblastoma, and H-35 cells as well as in rat liver, which inhibits ODC activity. Spermidine and spermine, distal products of ODC activity, also induce the synthesis of a similar protein in H-35 cells. These ODC-inhibitors are heat-labile, trypsin-sensitive, and their induction is dependent upon protein synthesis. They have short half-lives which range from 18 to 66 min; these half-lives are similar to those of the ODC derived from the same source. They are noncompetitive inhibitors of ODC activity with an apparent molecular weight of 26,500. Each inhibitor crossreacts with the ODC's of the other cells and forms an enzyme-inhibitor complex which is stable during Sephadex chromatography; however, after treatment with ammonium sulfate, enzyme and inhibitor activities can be dissociated and recovered intact from the same column. We propose the name antizyme for proteins whose synthesis is induced by the proximal or distal products of the enzyme they inhibit.
Synthesis of yeast histones in the cell cycle.
Authors: Moll R , Wintersberger E
Published: May 2006

The yeast, Saccharomyces cerevisiae, contains four types of histones resembling histones H3, H2b, H2a, and H4 of animal cells. These proteins are synthesized primarily, if not exclusively, in the S-phase of the cell cycle. This result is discussed with reference to the insensitivity of ongoing DNA replication in yeast to inhibitors of protein synthesis.
Structure of a nicked DNA-protein complex isolated from simian virus 40: covalent attachment of the protein to DNA and nick specificity.
Authors: Kasamatsu H , Wu M
Published: May 2006

A portion of the nicked circular DNA isolated from purified simian virus 40 contains a protein-DNA complex in which protein(s) is covalently attached to the end of a DNA single strand. (Nicked DNA is double-stranded DNA that contains at least one single-strand scission.) The protein was visualized by electron microscopy and labeled in vitro with 125I. The bond between the protein and the DNA is stable in alkali, 4 M guanidine-hydrochloride, 3.86 M hydroxylamine (pH 4,23), and in 98% formamide. Most of the molecules in the nicked circular DNA fraction contained one nick. The nick occurs on either of the two complementary strands; the specific nick sites on the two strands are staggered, but lie within a few hundred nucleotides of each other.
Cooperative interactions of tetrahydrofolate with purified pig kidney serine transhydroxymethylase and loss of this cooperativity in L1210 tumors and in tissues of mice bearing these tumors.
Authors: Kumar P M , North J A , Mangum J H , Rao N A
Published: May 2006

Serine transhydroxymethylase (5,10-methylenetetrahydrofolate: glycine hydroxymethyl transferase, EC 2.1.2.1) purified 200-fold from pig kidneys showed cooperative interactions with tetrahydrofolate with a Hill coefficient (n value) of 3.9 and a substrate concentration at 50% of maximum velocity, the S(0.5) value, of 0.5 mM. The enzyme in mouse liver and kidney homogenates also showed cooperative interactions with tetrahydrofolate. However, the enzyme obtained from L1210 solid tumors of mice, and from livers and kidneys of mice inoculated with L1210 cells exhibited hyperbolic saturation kinetics and gave a Michaelis constant, Km, value of 0.5 mM for tetrahydrofolate. The interaction of serine with the enzyme from pig kidney, from tissues of normal or tumor-bearing mice, or from L1210 tumors was hyperbolic with a Km of 0.9 mM. The specific activities of the enzyme in the L1210 tumor and in mouse liver were 10-fold higher than in pig or mouse kidney. There was no significant change in the levels of the enzyme in mouse liver and kidney on inoculation with L1210 cells. These results suggest that a tumor can bring about biochemical changes in tissues that are distal to the tumor.
Observation of individual carboxyl groups in hen egg-white lysozyme by use of high field 13C-nuclear magnetic resonance.
Authors: Shindo H , Cohen J S
Published: May 2006

Several of the carboxyl carbon atom resonances of hen egg-white lysozyme (mucopeptide N-acetylmuramoyl hydrolase, EC 3.2.1.17) have been resolved by 13C-nuclear magnetic resonance (NMR) at 68 MHz. The change in chemical shift of the carboxyl carbon atom resonances, as a function of pH, has enabled the distinction of these resonances against the background of many nontitrating carbonyl group resonances. Several apparent microscopic ionization constants have been determined from the carboxyl group NMR titration curves, and possible assignments are discussed. Preliminary experiments were carried out in the presence of cobaltous ion, and selective shifts of several resonances were observed. Our results indicate the possibility of the direct observation of a wide range of single functional groups of proteins in solution by NMR techniques.
Stimulation of fetal hemoglobin synthesis in bone marrow cultures from adult individuals.
Authors: Papayannopoulou T H , Brice M , Stamatoyannopoulos G
Published: May 2006

The regulation of fetal hemoglobin in adult erythroid cells was investigated with bone marrow cultures. Fetal hemoglobin (Hb F) was identified in individual erythroid colonies with fluorescent antibodies against Hb F and synthesis of gamma chains was determined with analyses of radioactive globins. The appearance of fetal hemoglobin in erythroid colonies was clonal. All the cells of the Hb F synthesizing colonies contained fetal hemoglobin. The frequency of erythroid colonies showing Hb F was higher than expected compared to the frequency of Hb F containing cells in the blood. Production of Hb F in culture, as shown by analysis of the radioactive globins, was 5 to 14 times higher than baseline Hb F synthesis. These results suggest that the ability for gamma chain synthesis in erythroid cells is determined at or above the level of the precursor cell from which the erythroid colonies, in vitro, derive (probably an erythropoietin responsive stem cell), and that stimulation of fetal hemoglobin synthesis in adult erythroid cells is possible.
Locations of chromosomal proteins in polytene chromosomes.
Authors: Alfageme C R , Rudkin G T , Cohen L H
Published: May 2006

D1, a nonhistone chromosomal protein rich in both basic and acidic amino acids, has been localized at a limited number of specific loci in polytene chromosomes of Drosophila melanogaster. H2B, a nucleosomal histone, and H1, a nonnucleosomal histone, are both found throughout most chromosomal regions.
Rates of evolution in seed plants: Net increase in diversity of chromosome numbers and species numbers through time
Authors: Levin D. A. , Wilson A. C.
Published: May 2006

An approach was made to the problem of estimating rates of chromosomal evolution in plants. This was done by considering variability in chromosome number within genera whose ages are known approximately from fossil and biogeographic evidence. The relative increases in chromosome number diversity per lineage per unit time were as follows: herbaceous angiosperms, 100; woody angiosperms, 14; conifers, 2; and cycads, 0. Rates of increase in species diversity were estimated in an analogous way. These rates were strongly correlated with the karyotypic rates.

These evolutionary rate differences between major groups of seed plants are largely explicable in terms of the breeding structures of populations. Herbs usually have small to moderate effective population sizes, and relatively high dispersability. By contrast, woody angiosperms and gymnosperms are usually obligate outbreeders with large effective population sizes and low dispersability. Thus the probability of fixing and dispersing new karyotypes or novel character ensembles is higher in herbs than in other seed plants.
Rheumatoid factor and tumor-host interaction.
Authors: Twomey J J , Rossen R D , Lewis V M , Laughter A H , Douglass C C
Published: May 2006

In this survey for rheumatoid factor (RF) seropositivity on patients with neoplasms, an 85% rate of positive screening tests was recorded under certain circumstances. This high rate of RF seropositivity occurred after irradiation and/or chemotherapy of breast and lung cancers. Treated patients with breast cancers who had no evidence of residual tumor had an 89% rate of positive RF tests. Conversely, the incidence of RF seropositivity was low among untreated patients with similar tumors and treated patients with glioblastomas or multiple myeloma. The administration of cytotoxic drugs (e.g., azathiprene) was not itself associated with RF production even in renal allograft recipients. The data indicate that RF production occurs frequently after therapy of certain tumors and suggest that in these circumstances RF may be an expression of tumor-host interaction.
Maximal functions: Spherical means
Authors: Stein Elias M.
Published: May 2006

Let [unk](
f
)(
x
) denote the supremum of the averages of
f
taken over all (surfaces of) spheres centered at
x
. Then
f
→ [unk](
f
) is bounded on

L
p

(R

n

), whenever
p
>
n
/(
n
- 1), and
n
≥ 3.
Hydrogen donor system for Escherichia coli ribonucleoside-diphosphate reductase dependent upon glutathione.
Authors: Holmgren A
Published: May 2006

E. coli B tsnC 7004, an E. coli B/1 mutant with normal phenotype unable to replicate phage T7 DNA [Chamberlin, M. (1974)J. Virol. 14,509-516], contained no detectable level of thioredoxin when assayed with ribonucleotide reductase (2'-deoxyribonucleoside-diphosphate:oxidized-thioredoxin 2'-oxidoreductase, EC 1.17.4.1). Gently lysed E. coli tsnC 7004 cell extracts reduced CDP when supplemented with NADPH as efficiently as the parent strain E. coli B/1 despite the lack of thioredoxin, indicating the presence of another hydrogen transport system. This could be divided into two parts by heat treatment at 85degrees; one heat-stable fraction, which was active in the presence of dithiothreitol or glutathione, and one heat-labile fraction. Addition of yeast glutathione reductase [NAD(P)H:oxidized-glutathione oxidoreductase, EC 1.6.4.2] to the heated extracts restored full activity. The results demonstrate a novel hydrogen transport system in E. coli consisting of NADPH, glutathione, glutathione reductase, and a heat-stable enzyme called "glutaredoxin". Reduced glutathione at physiological concentrations functions as hydrogen donor for ribonucleotide reduction only in the presence of glutaredoxin. Glutaredoxin was not reduced by E. coli thioredoxin reductase (NADPH:oxidized-thioredoxin oxidoreductase, EC 1.6.4.5) and showed no crossreaction with antibodies against thioredoxin. These results demonstrate the existence of two different electron transfer systems from NADPH to deoxyribonucleotides and provide a function for glutathione in DNA synthesis.
Hybridization of RNA to double-stranded DNA: formation of R-loops.
Authors: Thomas M , White R L , Davis R W
Published: May 2006

RNA can hybridize to double-stranded DNA in the presence of 70% formamide by displacing the identical DNA strand. The resulting structure, called an R-loop, is formed in formamide probably because of the greater thermodynamic stability of the RNA-DNA hybrid when it is near the denaturation temperature of duplex DNA. The rate of R-loop formation is maximal at the temperature at which half of the duplex DNA is irreversibly converted to single-stranded DNA (the strand separation temperature of tss) of the duplex DNA and falls precipitously a few degrees above or below that temperature. This maximal rate is similar to the rate of hybridization of RNA to single-stranded DNA under the same conditions. At temperatures above the tss the rate is proportional to the RNA concentration. However, at temperatures below tss the rate of R-loop formation is less dependent upon the RNA concentration. Once formed, the R-loops display considerable stability; the formamide can be removed and the DNA can be cleaved with restriction endonucleases without loss of R-loop structures.
Kinetics of branch migration in double-stranded DNA.
Authors: Thompson B J , Camien M N , Warner R C
Published: May 2006

The rate of branch migration in double stranded DNA has been measured by the use of a unique substrate formed by the action of the EcoRI restriction endonuclease on the dimeric figure-8 configuration of the replicative form DNA of phage G4. The figure-8 and the X-form derived from it contain a junction of the kind postulated to occur in the Holliday structure and to be an essential feature of a number of models of recombination. In the X-form this junction can branch migrate to an irreversible terminal configuration consisting of two linear monomers. The disappearance of X-forms was measured by electron microscopy. A treatment of branch migration as a random walk process was developed to permit the determination of the rate of the intrinsic process, a step movement of the junction by a distance of one base pair. A value of about 6 kilobase pairs per sec at 37 degrees was obtained.
New low resolution model for 50S subunit of Escherichia coli ribosomes.
Authors: Stuhrmann H B , Haas J , Ibel K , Wolf B , Koch M H , Parfait R , Crichton R R
Published: May 2006

Neutron low angle scattering studies of the 50S subunit of E. coli ribosomes with the contrast variation method reveals large fluctuations in the scattering density. A region of relatively low scattering density, rich in proteins, surrounds an RNA-rich core of higher scattering density. The centers of mass of the RNA and protein parts of the 50S subunit are separated by a distance (20 A) that is considerably smaller than that reported in previous studies.
gamma-Glutamyl transpeptidase, a lymphoid cell-surface marker: relationship to blastogenesis, differentiation, and neoplasia.
Authors: Novogrodsky A , Tate S S , Meister A
Published: May 2006

gamma-Glutamyl transpeptidase, an enzyme that catalyzes gamma-glutamyl transfer from gamma-glutamyl compounds to amino acid and peptide acceptors, and which is known to be localized in the membranes of many epithelial cells, was found in a variety of lymphoid cells. The lymphoid cell enzyme is located on the cell surface, and exhibits substantially the same substrate specificity as the enzyme found in epithelial cells. Human and rat (but not mouse) lymphocyte gamma-glutamyl transpeptidase was stimulated by treatment of the cells with mitogens. Normal human peripheral B-cells were more active than T-cells, but the reverse relationship of activities was found in chronic lymphocytic leukemia lymphocytes. Human lymphoblastic lines vary markedly in activity. In general, cell lines with B- and T-characteristics from patients with lymphoproliferative diseases had much lower activities than those of B-cell lines derived from normal subjects. The highest activity found was in a human myeloma line active in synthesis of an immunoglobulin light chain. The data indicate that gamma-glutamyl transpeptidase is a surface marker reflecting differentiation in normal and neoplastic cells.