bluuebunny/crossref_metadata_2025 huggingface dataset:
Deletion mutants of simian virus 40 defective in biosynthesis of late viral mRNA.
Authors: Lai C J , Khoury G
Published: May 2006

Deletion mutants of simian virus 40 defective in late gene functions have been examined for genetic elements that control the biosynthesis of the viral mRNAs. Mutant-specific RNA from infected cells was identified by CH3Hg/(OH)/agarose gel electrophoresis and mapped by the nuclease S1 technique. Altered RNA species, shortened by a size equivalent to the deletion region, can be detected in cells infected with these mutants lacking sequences within the body RNA segments. On the other hand, mutants that lack the 5'-end of the body sequences (a splice junction) fail to accumulate the respective shortened RNA species. In particular, mutant dl-2301 whose deletion includes both the leader and body splice junctions plus the intervening sequences, exhibits a polar effect on a distal gene. Whereas the late region of dl-2301 can be transcribed normally, the mutant defect appears to be associated with little or no accumulation of the mutant-specific late RNA in the infected cells. These results suggest that splice junctions or the intervening sequences, or both, in the viral genome are control signals for post-transcriptional processing of the viral RNA.
Probabilistic theory of the three-phase structure seminvariant in the space group
P
1̄
Authors: Hauptman Herbert
Published: May 2006

By embedding the three-phase structure seminvariant
T
and its symmetry-related variants in suitable quintets
Q
, one obtains the extensions
Q
of the seminvariant
T
. Because of the space group-dependent relationships among the phases,
T
is simply related to its extensions
Q
. In this way the probabilistic theory of the seminvariant
T
is reduced to that of the quintets
Q
, which is well developed. In particular, the neighborhoods of
T
are defined in terms of the neighborhoods of the
Q
s. The conditional probability distribution of the structure seminvariant
T
, given the seven magnitudes in its first neighborhood, is described for the space group
P
1̄. The distribution yields a reliable estimate (0 or π) for
T
in the favorable case that the variance of the distribution happens to be small.
Low stereoselectivity in methylacetylene and cyclopropene reductions by nitrogenase.
Authors: McKenna C E , McKenna M C , Huang C W
Published: May 2006

The stereochemistry of reductions catalyzed by nitrogenase in 2H2O has been investigated by using allene, methylacetylene, and cyclopropene as substrates. Deuterium labeling patterns in the reduction products were determined by mass spectroscopy, infrared spectroscopy, 2H-decoupled 220-MHz 1H NMR, and 1H-decoupled 30.7-MHz 2H NMR. Reduction of allene gave pure [2,3-2H2]propene. Reduction of methyl acetylene gave a 1.8:1.0 mixture of [cis- and [trans-1,2-2H2]propene. (Similar reduction of acetylene reportedly gave virtually all [cis-1,2-2H2]ethylene.) Reduction of cyclopropene gave [cis-1,2-2H2]cyclopropane and a mixture of [2H2]propenes. The major propene 2H2 isomers formed were [trans-1,3-2H2]-propene (approximately 2), [cis-1,3-2H2]propene (approximately 1) and [2,3-2H2]propene (approximately 1). Cyclopropene appears to be unique as a nitrogenase substrate in that it simultaneously undergoes parallel reductions, one of which proceeds with high stereoselectivity while the other proceeds with low stereoselectivity. The weakly selective stereochemistry observed in these reductions is not consistent with a completely concerted dual proton-dual electron transfer mechanism. The results provide a basis to probe stereochemical effects in nitrogenase and in biomimetic model systems.
Export without proteolytic processing of inner and outer membrane proteins encoded by F sex factor tra cistrons in Escherichia coli minicells.
Authors: Achtman M , Manning P A , Edelbluth C , Herrlich P
Published: May 2006

Most tra proteins encoded by the Escherichia coli F sex factor are incorporated into the minicell envelope. We have now assigned the tra proteins to cytoplasm (TraIp and 2b), inner membrane (TraEp, TraMp, and TraSp), and outer membrane (6e, TraAp, TraBp, TraJp, TraKp, TraLp, and TraTp). two proteins, TraDp and 6d, were associated with both inner and outer membranes. The proteins exported to the inner or outer membranes did not undergo proteolytic cleavage (processing) whereas beta-lactamase was processed normally.
Hydrophilic region of lecithin membranes studied by bromothymol blue and effects of an inhalation anesthetic, enflurane
Authors: Mashimo Takashi , Ueda Issaku , Shieh Donald D. , Kamaya Hiroshi , Eyring Henry
Published: May 2006

A pH-indicator dye, bromothymol blue, was used to probe the hydrophilic surface of dimyristoyl-, dipalmitoyl-, and distearoylphosphatidylcholine bilayer vesicles. The apparent pK of the surface-adsorbed dye was larger than the bulk pK value. The contribution of the choline positive charge on the dissociation constant of the dye adsorbed on the vesicle surface was estimated by screening the charge interaction with 2 M KCl. The effective surface potentials interacting with the dye were thus estimated to be 33.2, 45.6, and 46.8 mV, respectively, for the dimyristoyl-, dipalmitoyl-, and distearoylphosphatidylcholine vesicles. From the differences between the obtained effective potentials and the calculated surface potentials of the charge-determining plane of the choline head, the distances between the prototropic part of the dye and the choline charge-determining plane were estimated to be 10.5, 8.0, and 7.8 Å, respectively. These values were obtained at 25°C; the dimyristoylphosphatidylcholine membrane was in the liquid-crystalline phase and the other two were in the solid gel phase. Addition of an inhalation anesthetic, enflurane, decreased the distance in the dimyristoylphosphatidylcholine vesicles and increased the distance in the dipalmitoyl- and distearoylphosphatidylcholine vesicles. The increase of precessional motion of choline head by the inhalation anesthetic is apparently responsible for the changes.
Change in specificity of antibodies to a random synthetic branched polypeptide in mice tolerant to its ordered analogs
Authors: Schwartz Michal , Parhami Behnaz , Mozes Edna , Sela Michael
Published: May 2006

The crossreactivity between the random synthetic polypeptide antigen, (Tyr,Glu)-poly(DLAla)- -poly(Lys), and its ordered sequence analogs, (Tyr-Tyr-Glu-Glu)-poly(DLAla)- -poly(Lys) and (Tyr-Glu-Tyr-Glu)-poly(DLAla)- -poly(Lys), has been studied on the level of tolerance induction. Induction of tolerance to the random (Tyr,Glu)-poly(DLAla)- -poly(Lys) affected the response of the tolerant mice to the homologous antigen as well as to (Tyr-Tyr-Glu-Glu)-poly(DLAla)- -poly(Lys), which was shown previously to represent the major determinant of (Tyr,Glu)-poly(DLAla)- -poly(Lys). In contrast, these mice responded with high antibody titers to the hardly crossreacting (Tyr-Glu-Tyr-Glu)-poly(DLAla)- -poly(Lys). Mice tolerant to the ordered peptide antigen (Tyr-Glu-Tyr-Glu)-poly(DLAla)- -poly(Lys) did not respond to the homologous polypeptide; however, their immune response to either (Tyr-Glu)-poly(DLAla)- -poly(Lys) or (Tyr-Tyr-Glu-Glu)-poly(DLAla)- -poly(Lys) was not affected. Mice that were tolerant to (Tyr-Tyr-Glu-Glu)-poly(DLAla)- -poly(Lys) responded well to (Tyr-Glu-Tyr-Glu)-poly(DLAla)- -poly(Lys). Furthermore, these mice produced high antibody titers after immunization with the random (Tyr,Glu)-poly(DLAla)- -poly(Lys). However, the antibodies produced were not specific to the major determinant of (Tyr,Glu)-poly(DLAla)- -poly(Lys), namely, Tyr-Tyr-Glu-Glu, but were directed to minor determinants of the random polypeptide, including Tyr-Glu-Tyr-Glu, which are not immunopotent when nontolerant mice are immunized with (Tyr,Glu)-poly(DLAla)- -poly(Lys). Thus, whereas antigenic specificity reflects itself also at the level of tolerance induction, the animals that had been made tolerant are capable of responding to previously silent antigenic determinants.
Abelson antigen is expressed on hematopoietic spleen colony-forming cells from mice carrying the Av-2S virus sensitivity gene.
Authors: Risser R
Published: May 2006

Abelson antigen is a cell-surface determinant specifically induced by the Abelson murine leukemia virus (A-MuLV); this antigen is also expressed on uninfected bone marrow of BALB/c mice. Antisera that contained antibody to Abelson antigen were cytotoxic for the spleen colony-forming cells (CFU-S) of adult bone marrow from BALB/c mice. Absorption tests with appropriate tissues and direct cytotoxic tests with bone marrow CFU-S from several mouse strains confirmed that the sensitivity of BALB/c CFU-S to lysis by anti-Abelson-antigen antisera was due to expression of Abelson antigen. Spleen or bone marrow from BALB/c mice undergoing hematopoietic regeneration amplified Abelson antigen expression, although no expression of Abelson antigen was observed on regenerating C57BL/B6 bone marrow or spleen. The presence of Abelson antigen on bone marrow cells of seven recombinant inbred strains coincided with the inheritance of sensitivity alleles at the Av-2 locus, a gene that determines susceptibility to A-MuLV lymphoma induction. These results indicate that expression of Ableson antigen may have a physiologic function in hematopoietic differentiation and a pathologic role in A-MuLV lymphomagenesis.
Structural studies of of "active complex" of bleomycin: assignment of ligands to the ferrous ion in a ferrous-bleomycin-carbon monoxide complex.
Authors: Oppenheimer N J , Rodriguez L O , Hecht S M
Published: May 2006

Proton NMR studies at 360 MHz establish the binary Fe(II)-bleomycin complex to be paramagnetic with a spectrum covering 70 ppm. Addition of carbon monoxide generates a stable, diamagnetic Fe(II)-bleomycin-CO complex that is a putative structural analog of the "active" Fe(II)-bleomycin-O2 complex. The following six groups have been determined to be coordinated to the Fe(II) ion from analysis of the highly resolved 1H NMR spectra of this complex: CO, the primary and secondary amine nitrogens of the beta-aminoalanine moiety, the carbamoyl moiety on the 3-position of mannose, the pyrimidine N-1, and the imidazole N-1. The Fe(II)-bleomycin-CO complex binds to DNA, as shown by fluorescence quenching experiments, but Fe(II)-bleomycin-CO does not mediate thymine release. These results necessitate a major revision in the current model for metal coordination to bleomycin.
Detection of proteins like human gamma and beta globins in Escherichia coli carrying recombinant DNA plasmids.
Authors: Wilson L B , Grenett H E , Doran D M , Garver F A , Wilson J T
Published: May 2006

Escherichia coli strain chi 1776 carrying recombinant DNA plasmids containing cDNA copies of human beta or gamma globin mRNAs has been shown by radioimmunoassay to synthesize polypeptides antigenically related to the beta and gamma chains of human hemoglobin. The gamma and beta polypeptides have been enriched from lysates on immunoabsorbent columns containing hemoglobin antibodies and shown to specifically inhibit the antigen-antibody binding between 125I-labeled hemoglobin and the homologous antibody but not other hemoglobin-antihemoglobin reactions. Clone JW151, which is known to contain a complete copy of the coding portion of the gamma globin mRNA, has been shown to produce a protein that reacts specifically with antibody to the chain of fetal hemoglobin, hemoglobin Kenya, and hemoglobin Bart's.
Photoreversible absorbance changes in solutions of allophycocyanin purified from
Fremyella diplosiphon
: Temperature dependence and quantum efficiency
Authors: Ohad Itzakh , Clayton Roderick K. , Bogorad Lawrence
Published: May 2006

Preparations of allophycocyanin isolated from the alga
Fremyella diplosiphon
show light-induced optical absorbance changes that suggest the presence of a photoconvertible component [Formula: see text] similar to the algal pigments described by J. Scheibe [(1972)
Science
176, 1037-1039]. At pH < 4 the allophycocyanin has an absorption maximum at 620 nm. Red illumination causes a loss of absorbance in the red, centered at 620 nm, and subsequent green illumination restores the lost absorbance. We have studied this photoconversion at temperatures between 200 K and 307 K, analyzing the results in terms of photostationary states established under red (640 nm) and green (550 nm) light. As the temperature was lowered to 260 K, the state P
r
became progressively favored; the reaction P
r
→ P
g
induced by red light was attenuated but the reaction P
g
→ P
r
induced by green light was not. Decreasing the temperature from 260 K to 200 K had no further effect. Two distinct and simple models can account for this curious temperature dependence. By analyzing the kinetic and steady-state data, with reasonable estimates of the molar extinction coefficients of P
r
and P
g
, we computed quantum efficiencies greater than 15% for the photoconversion at 300 K. We deduced that a conversion of “all P
r
” to “all P
g
” should produce a fractional absorbance change Δ
A/A
at 620 nm equal to 0.1. If the chromatic adaptation response of intact
F. diplosiphon
shows the unusual temperature dependence reported here, the system P
r
⇌ P
g
will be implicated in mediating this response.
Biochemical and morphologic studies on diabetic rats: effects of sucrose-enriched diet in rats with pancreatic islet transplants.
Authors: Eder H A , Novikoff P M , Novikoff A B , Yam A , Beyer M , Gidez L I
Published: May 2006

Isolated pancreatic islets were administered to Lewis rats with streptozotocin-induced diabetes. Then the rats were fed either a semisynthetic diet containing 60% (wt/wt) sucrose for 3 weeks or were continued on chow. Transplantation resulted in a decrease in serum glucose, an increase in serum insulin, and a marked decrease in serum triacylglycerol, particularly in the sucrose-fed diabetic rats. In these rats, in demarcated areas of hepatocytes surrounding portal vein termini, lipid was deposited in the cytosol and large lipoprotein particles engorged the Golgi apparatus, Golgi-derived secretory vacuoles, and GERL. This model permits observation of the effects of pancreatic islet hormones on lipogenesis by hepatocytes in situ.
Completely integrable systems and groups generated by reflections
Authors: Gutkin Eugene , Sutherland Bill
Published: May 2006

We introduce a class of quantum Hamiltonian systems with δ-function potential, related to groups generated by reflections. They generalize the system of equal elastic particles on the line. We show that these systems are completely integrable and we integrate them explicitly. Then we apply our technique to obtain identities for groups generated by reflections.
Correlation of polypeptide composition with functional events in acetylcholine receptor-enriched membranes from Torpedo californica.
Authors: Moore H P , Hartig P R , Raftery M A
Published: May 2006

Membrane vesicles containing partially inactivated acetylcholine receptor (AcChoR) channels may produce a full 22Na+ flux response because an excess of channels may exist above the level needed to completely empty the vesicles of ions. Therefore, attempts to use ion flux amplitudes as indicators of AcChoR function may fail due to the presence of these excess AcChoR channels. Random inactivation of variable fractions of AcChoR channels in vesicles by the irreversible binding of the neurotoxin alpha-bungarotoxin provides a tool for assessing the size of the excess receptor population. Using this approach, we predict that the dependence of the flux response on partial inactivation by alpha-bungarotoxin will drastically change if an essential AcChoR component is substantially removed from the membranes. Membranes from which Mr 43,000, Mr 90,000, and other polypeptides had been substantially removed by base extraction exhibited a flux response after random inactivation that was indistinguishable from that of untreated membranes. Therefore, those components which are substantially removed by base extraction do not appear to be essential for AcChoR-mediated ion flux.
Glucocorticoid modulation of casein gene transcription in mouse mammary gland.
Authors: Ganguly R , Mehta N M , Ganguly N , Banerjee M R
Published: May 2006

The influence of cortisol and prolactin on casein gene expression in the mammary gland of lactating BALB/c mice was measured by using a specific cDNA probe to 15S casein mRNA (cDNAcsn). Casein mRNA (mRNAcsn) level in the mammary gland was decreased by 85% 5 days after adrenal ablation, but then was increased 4.4-fold 12 hr after a single injection of hydrocortisone-21-acetate. An 80% decrease in serum prolactin level, induced by the prolactin inhibitor 2-bromo-alpha-ergocryptin (CB-154), did not alter the level of mRNAcsn in the gland. Specific transcription of the casein gene in nuclei isolated from lactating mammary glands was measured by cDNAcsn hybridization to the in vitro synthesized Hg-CTP-containing RNA (Hg-RNA), which was purified by SH-agarose chromatography. The level of the mRNAcsn in Hg-RNA synthesized in the isolated nuclei was 0.09% and this was decreased 85% by alpha-amanitin, indicating that the mRNAcsn sequences in the Hg-RNA were the products of RNA polymerase II-directed DNA-dependent RNA synthesis. Transcription of the mRNAcsn in isolated nuclei was decreased by 70% 5 days after adrenalectomy and a single injection of the glucocorticoid then increased the transcription level 2-fold at 6 hr. Essentially no alteration of the level of transcription was detectable in mammary nuclei isolated from lactating mice with 80% decreased serum prolactin level, induced by CB-154 treatment. The results thus demonstrate a glucocorticoid involvement on the modulation of casein gene expression at the transcriptional level of control.
Analysis of genetic complementation by whole-cell microtechniques in fibroblast heterokaryons.
Authors: Gravel R A , Leung A , Saunders M , Hösli P
Published: May 2006

A whole-cell microtechnique for the determination of complementation of human metabolic disorders is presented. This procedure permits the isolation of individual multinucleate cells produced by cell fusion for the quantitative evaluation of complementation. Mutant fibroblasts with a deficiency of propionyl-CoA carboxylase activity (EC 6.4.1.3) that had been mapped to complementation groups pcc and bio were used to evaluate the microtechnique. Complementation was monitored by the determination of [14C]propionate incorporation into cellular macromolecules. Single cells or a small number of cells were isolated from plastic film dishes after radioactive incubation by cutting out the portion of the plastic film holding the desired cells. Isotope incorporation was linear in 10-50 unfused cells and in 10-50 fused normal cells containing five or more nuclei. There was also a direct correlation between the nuclear content of cells and the amount of isotope incorporated. Three pcc and two bio mutants were fused in pairwise combinations by means of polyethylene glycol and complementation was determined by isotope incorporation in sets of 50 multinucleate cells, each cell isolated individually. The results agreed with autoradiographic data for both complementing and noncomplementing strains. The method is quantitative and gives severalfold higher sensitivity than current procedures. The method can be applied to the complementation analysis of a wide variety of inherited disorders of intermediary metabolism.
Cell-free synthesis of mouse H-2 histocompatibility antigens.
Authors: Jay G , Ferrini U , Robinson E A , Khoury G , Appella E
Published: May 2006

The mRNAs coding for the histocompatibility (H-2) antigens of the mouse have been identified by cell-free translation of poly(A)-containing RNA obtained from the livers of mice (strain A/J), followed by immunoprecipitation of the cell-free products by using an antiserum directed against purified H-2a. Unlike the 47,000- and 46,000-Mr H-2 glycoproteins synthesized in splenic lymphocytes, the cell-free translation products have Mrs of 45,000 and 44,500, representing the unglycosylated forms of these antigens. The cell-free products are shown to be related to the H-2 antigens by competition immunoprecipitation with purified H-2a and by two-dimensional tryptic peptide mapping. The H-2 mRNAs which sediment at 17 S are found associated predominantly with membrane-bound polysomes and are actively translated in the liver where as many as 16 ribosomes are associated with each molecule of H-2 mRNA. The implications of these studies for molecular cloning and for an understanding of the organization and expression of the genes encoding these H-2 antigens are discussed.
Modulation of the classical pathway C3 convertase by plasma proteins C4 binding protein and C3b inactivator.
Authors: Gigli I , Fujita T , Nussenzweig V
Published: May 2006

We recently described the isolation from human serum of a serum protein (C4 binding protein) that functions as an essential cofactor for C3b inactivator in the proteolysis of fluid-phase C4b and to a much lesser extent, C3b. We show here the role of C4 binding protein in the formation and function of the classical pathway C3 convertase (C42). C4 binding protein interferes with the assembly of the membrane-bound C3 convertase of the classical pathway and accelerates the decay of C42 in a dose-dependent fashion. Its removal from serum by means of specific immune absorption promotes the vigorous consumption of C3 after addition of C1; this effect is abolished by reconstitution with purified C4 binding protein. Although C4 binding protein inhibits the hemolytic function of cell-bound C4b, we did not detect any change in the structure of C4b even after prolonged incubations of EAC14 with C4 binding protein. For this reason, and on the basis of studies of the time required for maximal reactivity (Tmax) of cellular intermediates generated in the presence of C4 binding protein and limited amounts of C2, we conclude that the effects of C4 binding protein are probably mediated by displacing C2a from specific binding sites on C4b. In addition, C4 binding protein enhances the cleavage by C3b inactivator of the alpha' chain of cell-bound C4b. When EAC14 cells were incubated with both control proteins, the Tmax of the cells was prolonged and the lysis was markedly diminished. We conclude that C4 binding protein and C3b inactivator control the C3 convertase of the classical pathway in a fashion similar to that described for beta 1H and C3b inactivator in the alternative pathway.
Modulation by thymus-derived (T) cells of thyroid cell-stimulated prostaglandin E release by human peripheral blood mononuclear cells.
Authors: Yamamoto M , Takai N A , Rapoport B , Hinds W E
Published: May 2006

Cultures of plastic-adherent, human peripheral blood mononuclear cells generated prostaglandin E (PGE). Culture of the adherent cells (predominantly monocytes) with human thyroid cells enhanced PGE accumulation in the medium, although to a lesser degree than occurs with unseparated blood mononuclear cells. Recombination of the adherent cells with monocyte-depleted, nonadherent cells restored both basal and thyroid cell-stimulated PGE generation to the levels seen with unseparated cells. Thymus-derived (T) cells, obtained by rosetting with sheep erythrocytes, similarly enhanced both the adherent cell basal PGE production as well as the increased PGE accumulation that occurs in the presence of thyroid cells (50-120% augmentation by the T cells). Significant augmentation of thyroid cell-stimulated PGE release by 10(5) adherent cells occurred with the addition of as few as 5 x 10(4) T cells. Culture medium transfer experiments and separation of cell types during culture by a semipermeable membrane provided evidence against the possibility that the adherent cells were releasing a factor that stimulated T-cell PGE generation or that T cells were releasing a factor that enhanced adherent cell PGE generation. The results suggest instead that this T-cell effect requires direct contact with the adherent cells. These data demonstrate the importance of human T cells in the release by adherent cells of PGE, a mediator of suppressor function by some immune cells.
Rhythmic patterns of discharge in hypothalamic neurosecretory neurons of cats and dogs.
Authors: Yamashita H , Koizumi K , Brooks C M
Published: May 2006

Recent studies in rats suggest that vasopressin- and oxytocin-secreting neurons in supraoptic nuclei and paraventricular nuclei of the hypothalamus show two different patterns of activity: one a "bursting" or rhythmic pattern and the other, irregular continuous discharges. This possibility was investigated in cats and dogs anesthetized with chloralose or Nembutal by recording electrical activity of single supraoptic and paraventricular neurons. Only some of the "identified" neurosecretory cells showed rhythmic, intermittent discharges ("bursting" cells in rats); the majority showed an irregular continuous firing pattern. Furthermore, the pattern of discharge sometimes changed from one ot the other during long periods of observation. This occurred without apparent stimulus in certain instances; in others, the rhythmic firing was associated with fluctuation in blood pressure and heart rate and was likely to be caused by changes in baroreceptor activity. Possible origins of rhythmic discharges and the physiological importance of such patterns in terms of hormone secretion are discussed.
13
C nuclear magnetic resonance study of the CO
2
activation of ribulosebisphosphate carboxylase from
Rhodospirillum rubrum
Authors: O'Leary Marion H. , Jaworski Robert J. , Hartman Fred C.
Published: May 2006

Ribulosebisphosphate carboxylase [3-phospho-D-glycerate carboxy-lyase (dimerizing), EC 4.1.1.39] from
Rhodospirillum rubrum
is activated by CO
2
and Mg
2+
.
13
C NMR spectra were determined for the unactivated enzyme and for enzyme that had been activated by
13
CO
2
and Mg
2+
. In addition to the expected resonance for H
13
CO
3
-
/CO
3
2-
at 161.8 ppm downfield from tetramethylsilane, the spectrum of the activated enzyme shows a broad resonance at 164.9 ppm. Analogy with previous NMR studies of
13
CO
2
binding to hemoglobin [Morrow, J. S., Keim, P., Visscher, R. B., Marshall, R. C. & Gurd, F. R. N. (1973)
Proc. Natl. Acad. Sci. USA
70, 1414-1418], to myoglobin, and to amino acids [Morrow, J. S., Keim, P. & Gurd, F. R. N. (1974)
J. Biol. Chem
. 249, 7484-7494] suggests that the CO
2
activation of ribulosebisphosphate carboxylase involves formation of a carbamate between an enzyme amino group and CO
2
.
Strand-specific attachment of avidin-spheres to double-stranded poliovirus RNA.
Authors: Richards O C , Ehrenfeld E , Manning J
Published: May 2006

Poliovirus-specific double-stranded RNA molecules containing covalently attached protein were coupled with a biotin ester through the protein moiety. Subsequent interaction of the RNA-biotin with avidin attached to electronopaque plastic spheres led to the formation of complexes that were easily visualized in the electron microscope. Avidinspheres were associated only with one end of the RNA-biotin molecules, as seen in the electron microscope. Avidin-sphere attachment to poliovirus double-stranded RNA is strand specific, as shown by molecular hybridization of strand-specific probes to the separated strands of denatured complexes. [3H]DNA complementary to polio virion RNA hybridized exclusively to the strands bearing associated spheres [(+) strands] whereas 125I-labeled virion RNA hybridized predominantly with strands without spheres [(-)strands]. This biotin-avidin labeling technique provides a means for the isolation of full-length poliovirus (-) strands and may provide a general means for isolation of double-stranded polynucleotides containing tightly attached protein.
IgM receptors on human lymphocytes: detection by direct binding.
Authors: Hardin J A , Nakaoka K K , Carboni J M
Published: May 2006

Radioiodinated IgM isolated from a patient with Waldenström macroglobulinemia binds with high avidity (apparent Ka = 2.5 x 10(9) M-1) to freshly isolated human peripheral blood lymphocytes. Binding occurred through the Fc region of the molecule and involved a receptor specific for immunoglobulins of the IgM class. The avidity and specificity of this binding are consistent with a biologic role for IgM receptors on lymphocytes.
Transfection of human lymphoblastoid cells with herpes simplex viral DNA.
Authors: Miller G , Wertheim P , Wilson G , Robinson J , Geelen J L , van der Noordaa J , van der Eb A J
Published: May 2006

The "calcium/dimethyl sulfoxide shock" method of transfection was adapted for use in human lymphoid cell cultures. One microgram of herpes simplex virus type 1 DNA regularly initiated virus replication in four lymphoblastoid cell lines. Per 10(5) cells exposed to 1 microgram of DNA, 0.5--5 cells formed an infectious center. The minimal infective dose of DNA was approximately 500 ng.
Specific binding of 125I-labeled beta-hexosaminidase A to rat brain synaptosomes.
Authors: Kusiak J W , Toney J H , Quirk J M , Brady R O
Published: May 2006

Purified human beta-hexosaminidase A (beta-N-acetylgulcosaminidase; 2-acetamido-2-deoxy-beta-D-glucoside acetamidodeoxyglucohydrolase, EC 3.2.1.30) has been labeled with 125I to high specific activity with the retention of 80% of its enzyme activity. The binding of this enzyme to sonicated synaptosomes from rat brain was shown to be a saturable and specific process. Glycoproteins containing a sialic acid-terminal oligosaccharide or a galactose-terminal oligosaccharide (i.e., alpha 1-acid glycoprotein and fetuin and their asialo derivatives) were strong inhibitors of the binding. In contrast, ovalbumin, which contains a mannose-rich oligosaccharide, and mannans were poor inhibitors of the binding. Of the monosaccharides tested, sialic acid, galactosamine, mannose, galactose, and lactose were inhibitory in decreasing potency of inhibition. Optimal binding occurred at pH 7.0 in the presence of 3 mM calcium ions. The binding was a linear function of synaptosomal protein concentration between 25 and 200 microgram of protein per assay and was directly proportional to time up to 3 hr, beyond which there was no further increase in specific binding. The data suggest a unique but complex mode of interaction of glycoproteins with receptors on synaptic membranes.
The pineal gland: a pacemaker within the circadian system of the house sparrow.
Authors: Zimmerman N H , Menaker M
Published: May 2006

Transplantation of pineal tissue into the anterior chamber of the eye rapidly reestablishes rhythmicity in arhythmic pinealectomized sparrows and also transfers the phase of the donor bird's rhythm to the host. Thus, the transplanted pineal does not merely permit rhythmicity to be expressed but rather transfers an oscillation that controls the remainder of the circadian system and restores the capacity for self-sustained rhythmicity. Long-term recordings, during which sparrosw were exposed to various lighting conditions, demonstrate a remarkable similarity between the circadian system in normal birds and that in birds bearing pineal transplants.
In vitro
synthesis of the Ca
2+
transport ATPase by ribosomes bound to sarcoplasmic reticulum membranes
Authors: Chyn Ted L. , Martonosi Anthony N. , Morimoto Takashi , Sabatini David D.
Published: May 2006

The calcium transport ATPase (

M
r

100,000) from sarcoplasmic reticulum membranes was synthesized in a cell-free translation system containing rough microsomes or detergent-treated bound polysomes from 14- to 16-day old chicken embryo muscles. Immunoprecipitates obtained from total translation mixtures treated with anti-ATPase antiserum contained 1.5% of the total radioactivity incorporated
in vitro
. A polypeptide with the electrophoretic mobility, isoelectric point, and [
35
S]methionine-labeled tryptic peptide pattern of the mature ATPase was a major component of these immunoprecipitates. By contrast, free polysomes from the same source, which were capable of high levels of
in vitro
protein synthesis, did not yield immunoprecipitable ATPase. ATPase synthesized in rough microsomes was not released by treatment with 10 mM EDTA in a high-salt medium (0.5 M KCl) which removes ribosomes and peripheral membrane proteins. Furthermore, labeled ATPase remained associated with the microsomes after these were treated with low concentrations of deoxycholate (0.1 mg/mg of protein in 0.3 ml) which release the luminal content of the vesicles. Only with higher deoxycholate concentrations (0.5 mg/mg of protein in 0.3 ml), which cause membrane dissolution, was the labeled ATPase found on the detergent extracts. These observations indicate that newly synthesized ATPase discharged from bound ribosomes is transferred directly to the sarcoplasmic reticulum membranes where it is incorporated as an integral membrane protein.
Myeloma proteins from NZB and BALB/c mice: structural and functional differences.
Authors: Loh E , Black B , Riblet R , Weigert M , Hood J M , Hood L
Published: May 2006

Structural and functional analyses of myeloma immunoglobulins from inbred BALB/c mice and humans have provided important insights into the structure of the antibody molecule and the expression and evolution of antibody genes. One important question concerning these analyses is whether the myeloma process selects, in a nonrandom manner, the lymphocytes to be transformed. The availability of myeloma tumors in a second inbred strain of mouse, NZB, permits us to approach this question. In this respect. the NH2-terminal amino acid sequences of 27 kappa light chains as well as data relating to the antigen-binding properties and immunoglobulin class distribution of NZB myeloma proteins are presented and compared with similar data from the BALB/c mouse. These studies suggest that the myeloma proteins from the BALB/c and NZB mice constitute two populations of immunoglobulins with distinct functional and structural properties. The implication of this observation are discussed.
Replication of an origin-containing derivative of plasmid RK2 dependent on a plasmid function provided in
trans
Authors: Figurski David H. , Helinski Donald R.
Published: May 2006

pRK212.2, a derivative of the broad host range plasmid RK2, contains two
Eco
RI cleavage fragments, A and B, neither of which can replicate by itself in
Escherichia coli
. Fragment A (41.7 kilobases), but not fragment B (14.4 kilobases), can be cloned by insertion into the unrelated plasmids mini-F and ColE1. Fragment B contains the origin of replication and the ampicillin-resistance determinant of RK2. Transformation of
E. coli
cells containing the mini-F-fragment A hybrid plasmid with fragment B DNA results in the recircularization and replication of fragment B as a nonmobilizable plasmid (pRK2067) with the copy number and incompatibility properties of RK2. Fragment B cannot be cloned in the absence of fragment A because the latter fragment suppresses a function, specified by fragment B, that results in loss of host cell viability. A small segment (2.4 kilobases) of fragment B that contains the RK2 origin of replication but no longer affects host cell growth in the absence of fragment A had been cloned previously by insertion into a ColE1 plasmid. This hybrid plasmid, designated pRK256, will replicate in
E. coli polA
mutants only when a fragment A-bearing helper plasmid is present. These results demonstrate that the potentially lethal function specified by fragment B of RK2 is not necessary for replication and that at least one
trans
-acting function is directly involved in RK2 replication.
Direct chemical method for sequencing RNA.
Authors: Peattie D A
Published: May 2006

Four different base-specific chemical reactions generate a means of directly sequencing RNA terminally labeled with 32P. After a partial, specific modification of each kind of RNA base, an amine-catalyzed strand scission generates labeled fragments whose lengths determine the position of each nucleotide in the sequence. Dimethyl sulfate modifies guanosine. Diethyl pyrocarbonate attacks primarily adenosine. Hydrazine attacks uridine and cytidine, but salt suppresses the reaction with uridine. In all cases, aniline induces a subsequent strand scission. The electrophoretic fractionation of the labeled fragments on a polyacrylamide gel, followed by autoradiography, determines the RNA sequence. RNA labeled at the 3' end yields clean cleavage patterns for each purine and pyrimidine and allows a determination of the entire RNA sequence out to 100-200 bases from the labeled terminus.
Fibroblast interferon induces synthesis of four proteins in human fibroblast cells.
Authors: Knight E , Korant B D
Published: May 2006

Treatment of human diploid fibroblasts with fibroblast interferon for 8 hr inhibited replication of vesicular stomatitis virus. When the total cell protein of cells treated with interferon for 8 hr was compared to the total cell protein of untreated cells by two-dimensional gel electrophoresis, the interferon-treated cells were found to contain four proteins not found in untreated cells. Addition of actinomycin D to the cells concurrently with interferon inhibited the synthesis of the four proteins. We conclude that these proteins are induced by interferon and that they may be involved in the inhibition of virus replication.
Solubilized and insolubilized bone morphogenetic protein.
Authors: Urist M R , Mikulski A , Lietze A
Published: May 2006

A bone morphogenetic protein (BMP) obtained in solution by digestion of demineralized rabbit cortical bone matrix with bacterial collagenase retains its biologically active conformation in a neutral salt/ethylene glycol mixture. BMP may be insolubilized by coprecipitation with calcium phosphate and resolubilized by chemical extraction with a neutral salt in the same solvent mixture. Upon concanavalin A-Sepharose chromatography, BMP is bound by hydrophobic interaction and carbohydrate recognition and is recovered by elution with either alpha-methyl mannoside or ethylene glycol solvent mixture. Implants of both eluates and the extracts of the coprecipitate in double-walled diffusion chambers induce transmembrane bone morphogenesis. BMP is not species specific; rabbit BMP induces new bone formation in the rat. The present observations indicate that BMP is a glycoprotein.
Inhibitors of membrane transport reduce lysosomal enzyme secretion from dogfish phagocytes and their killing of sea urchin eggs
Authors: Dunham Philip , Arvan Peter , Falkow Stephen , Hoffstein Sylvia , Weissmann Gerald
Published: May 2006

Blood phagocytes of the dogfish
Mustelus canis
attack oocytes of the sea urchin
Arbacia punctulata
, first provoking a surrogate fertilization response and then killing the eggs. To test the hypothesis that secretion of lysosomal contents is critical in this model of phagocyte-mediated cell injury, we studied effects of agents that modify lysosomal enzyme secretion. Inhibitors of membrane transport (>0.1 mM) inhibited postphagocytic secretion of lysosomal β-glucuronidase from dogfish phagocytes: phloretin > ethacrynate > furosemide > 4-acetamido-4′-isothiocyanostilbene-2,2′-disulfonic acid >> pyridoxal phosphate > ouabain. The same order of activity was found for inhibition by these agents of killing of
Arbacia
eggs by phagocytes. Cell activation (fertilization response) and cytotoxicity were quantitated both morphologically and by measurements of enzyme (β-glucuronidase, catalase) release. The agents neither inhibited fertilization responses of eggs to calcium ionophore A23187 nor impaired their viability. Vital staining demonstrated that ethacrynate prevented phagocytes from degranulating upon contact with zymosan particles. The data not only suggest that agents primarily known for their capacity to inhibit membrane transport systems can inhibit lysosomal enzyme secretion from phagocytes but also support the hypothesis that secretion of lysosomal contents mediates activation and killing of target cells in phagocyte-mediated tissue injury.
Contrasted modes of evolution in the same genome: allozymes and adaptive change in Heliconius.
Authors: Turner J R , Johnson M S , Eanes W F
Published: May 2006

Butterflies in the South American genus Heliconius have undergone a spectacular adaptive radiation (with convergent evolution between some lines) in their color patterns; this has been produced by natural selection for muellerian mimicry. The genetic basis of this radiation, shown by crossing highly differentiated races within two of the species, is homozygosity for alternative alleles at some half dozen loci. In complete contrast, allozyme loci in these butterflies are strongly heterozygous and show only frequency differences (never amounting to homozygosity of alternative alleles) between races; the amount of allozyme divergence is the same between races of H. erato and H. sara, although in color pattern the first forms marked races and the other does not. For the allozymes, there is a strong correlation over loci for rate of divergence between species and average heterozygosity. This is not true of the genes controlling color pattern. Heterozygosity of the enzymes is correlated with subunit molecular weight. Thus, different parts of the genome can evolve in different ways simultaneously; genes controlling color pattern in the "classical" mode, and allozymes in a different mode in which the rate of evolution is related to their heterozygosity (a "balance" or "neutral" mode).
Enhancement of the primary cytotoxic response to membrane by a lymphokine costimulator.
Authors: Rulon K , Talmage D W
Published: May 2006

The primary and secondary cytotoxic T cell responses of C57Bl/6 (H-2b) mouse spleen cells to P-815 membrane fragments (H-2d) were examined. The primary response required the addition of a supernatant from mitogen-stimulated spleen cells, or costimulator, to the culture medium. Costimulator had little effect on the secondary response unless the spleen cells were first passed through a nylon wool column. Our data suggested that secondary cultures produced their own costimulator and that adherent cells were required for its production. The possibility that adherent cells are needed to activate helper cells is discussed.
Coevolution in structured demes.
Authors: Slatkin M , Wilson D S
Published: May 2006

A simple model of coevolution in a subdivided population is considered. It is shown that, when there are frequency- and density-dependent interactions in each site, the sampling variation in numbers in each local site can lead to selection both through the dispersal process and through indirect effects. The model predicts that coevolved relationships between species can result from various interactions other than direct forms of competition and predation.
Metal cluster chemistry: Structure and stereochemistry in the polynuclear rhodium hydrides H
n
Rh
n
[P(OR)
3
]
2n
Authors: Brown R. K. , Williams J. M. , Fredrich M. F. , Day V. W. , Sivak A. J. , Muetterties E. L.
Published: May 2006

Crystallographic analyses of x-ray and neutron diffraction data have provided a definitive structural representation of {HRh[P(O-
i
-C
3
H
7
)
3
]
2
}
2
and {HRh[P(OCH
3
)
3
]
2
}
3
. These polynuclear hydrides are generated from square planar H
2
Rh[P(OR)
3
]
2
units by edge (hydrogen atom) sharing and by vertex (hydrogen atom) sharing to form the dimeric and trimeric structures, respectively. The square-planar units are held together through four-center and three-center two-electron Rh—H—Rh bonds in the dimer and trimer, respectively. The dimer and trimer molecules each add one molecule of hydrogen to form H[(
i
-C
3
H
7
O)
3
P]
2
RhH
3
Rh [P(O-
i
-C
3
H
7
)
3
]
2
and H
5
Rh
3
[P(OCH
3
)
3
]
6
, respectively. NMR spectral information has served to define the stereochemical features of these polyhydrides. The significance of this chemistry in the metal cluster-metal surface analogy is described.
Irreversible processes at nonequilibrium steady states
Authors: Fox Ronald Forrest
Published: May 2006

It is shown that a Liapunov criterion exists for the stability of nonequilibrium steady states. This criterion is based upon the fluctuation-dissipation relation, as was first pointed out by Keizer. At steady states, the Liapunov function is constructed from the covariance matrix for the thermodynamic variables. Unlike the situation around equilibrium, at steady states the covariance matrix and the “excess entropy” matrix are not equivalent. The excess entropy, which serves as the Liapunov function around equilibrium, does not work in this capacity at steady states. Keizer's Liapunov function must be viewed as the first correct candidate for a proper Liapunov function for steady states.
In situ
phosphorylation of the α subunit of eukaryotic initiation factor 2 in reticulocyte lysates inhibited by heme deficiency, double-stranded RNA, oxidized glutathione, or the heme-regulated protein kinase
Authors: Ernst Vivian , Levin Daniel H. , London Irving M.
Published: May 2006

Protein synthesis initiation in reticulocyte lysates is inhibited by heme deficiency, low levels of double-stranded RNA (dsRNA), oxidized glutathione (GSSG), or the purified kinase (HRI) that acts on the α polypeptide of eukaryotic initiation factor 2 (eIF-2α). The phosphoprotein profiles produced in lysates in response to these various conditions have been monitored directly in lysates after labeling for brief periods with pulses of [γ-
32
P]ATP. The [
32
P]phosphoprotein profiles were analyzed by electrophoresis in sodium dodecyl sulfate/polyacrylamide slab gels under conditions in which the HRI and eIF-2α polypeptides were clearly distinguished. All four modes of inhibition produced a rapid phosphorylation of eIF-2α compared to control lysates, which displayed little or no phosphorylation of eIF-2α. In heme-deficient lysates, phosphorylation of eIF-2α occurred rapidly both before and after the shut-off of protein synthesis; the delayed addition of hemin to these lysates resulted in a decrease in the phosphorylation of eIF-2α and the subsequent restoration of protein synthesis. These data suggest that rapid turnover of phosphate occurs at the site(s) of eIF-2α phosphorylation. In lysates inhibited by heme deficiency, GSSG, or added HRI, the phosphorylation of eIF-2α was accompanied by the rapid
in situ
phosphorylation of HRI. The inhibition of initiation induced by dsRNA was accompanied by the phosphorylation of eIF-2α and a 67,000-dalton polypeptide but not HRI. These observations
in situ
indicate that (
i
) the phosphorylation of eIF-2α is the critical event in these inhibitions of protein chain initiation, and (
ii
) the phosphorylation of HRI is associated with its activation in heme deficiency.
Heterogeneous flavonoid glucosyltransferases in purple derivatives from a controlling element-suppressed
bronze
mutant in maize
Authors: Dooner Hugo K. , Nelson Oliver E.
Published: May 2006

The
Ds
(Dissociation)-suppressed bronze mutant
bz-m2
(
DI
), which is extremely stable in the absence of the regulatory element
Ac
(Activator), becomes both somatically and germinally unstable when
Ac
is present. Instability in the germ line may result in the generation of stable (
Ac
-nonresponding), colored
Bz
′ derivatives. The characterization of several properties of the
Bz
-controlled enzyme UDPglucose: flavonoid 3-
O
-glucosyltransferase from mature kernel endosperms of 15 such
Bz
′ derivatives has revealed two distinct groups. The enzyme in group I
Bz
′ derivatives does not differ from the normal enzyme in the
Bz
progenitor allele of
bz-m2
(
DI
). Group II
Bz
′ derivatives, on the other hand, make altered, labile UDPglucose:flavonoid glucosytransferases different from the normal enzyme and probably different from each other. The significance of these two classes of derivatives and possible mechanisms involved in their origin are discussed.