bluuebunny/crossref_metadata_2025 huggingface dataset:
Contacts between hormone receptor and DNA double helix within a glucocorticoid regulatory element of mouse mammary tumor virus.
Authors: Scheidereit C , Beato M
Published: May 2006

Glucocorticoid hormones enhance the transcription of mouse mammary tumor virus DNA by mechanisms involving a direct interaction of the hormone receptor with four binding sites in a glucocorticoid regulatory element located between -72 and -192 base pairs upstream of the main transcription initiation site within the proviral long terminal repeat regions. Methylation at the N-7 position of any of three G residues within one of the binding sites prevents binding of the receptor. In addition, in the presence of the receptor, methylation by dimethyl sulfate is reduced at several G residues, indicating sites of contact between the receptor and DNA at these positions. The G residues in the hexanucleotide 5'-T-G-T-T-C-T-3' 3'-A-C-A-A-G-A-5' were protected by the receptor against MH2-specific gene. (iii) myc is followed by the 3'-terminal c region of about 400 nucleotides, which is colinear with that of Rous sarcoma virus except for a substitution near the 5' end of the long terminal repeat. It is concluded that MH2 contains two genes with oncogenic potential, the delta gag- mht gene, which is closely related to the delta gag-raf transforming gene of MSV 3611, and the myc gene, which is related to the transforming gene of MC29. Furthermore, it may be concluded that the cellular proto-onc genes, which on sequence transduction become viral onc genes, are a small group because among the 19 known onc sequences, 5 are shared by different taxonomic groups of viruses of which the mht /raf homology is the closest determined so far.
beta-Endorphin-induced analgesia is inhibited by synthetic analogs of beta-endorphin.
Authors: Nicolas P , Hammonds R G , Li C H
Published: May 2006

Competitive antagonism of human beta-endorphin (beta h-EP)-induced analgesia by synthetic beta h-EP analogs with high in vitro opiate receptor binding to in vivo analgesic potency ratio has been demonstrated. A parallel shift of the dose-response curve for analgesia to the right was observed when either beta h-EP or [ Trp27 ] -beta h-EP was coinjected with various doses of [Gln8, Gly31 ]-beta h-EP-Gly-Gly-NH2, [Arg9,19,24,28,29]-beta h-EP, or [ Cys11 ,26, Phe27 , Gly31 ]-beta h-EP. It was estimated that the most potent antagonist, [Gln8, Gly31 ]-beta h-EP-Gly-NH2, is at least 200 times more potent than naloxone.
Multinucleation-induced improvement of the spreading of transformed cells on the substratum.
Authors: Lyass L A , Bershadsky A D , Gelfand V I , Serpinskaya A S , Stavrovskaya A A , Vasiliev J M , Gelfand I M
Published: May 2006

Multinucleation of various cultured cells was produced by polyethylene glycol-induced fusion or by cytochalasin-induced block of mitosis. It was found that multinucleation induced by both methods considerably improved deficient spreading of all the tested transformed fibroblastic lines; average substratum area occupied by one cell and divided per number of nuclei was 2.0-2.5 times larger for multinucleated cells than for mononucleated ones. Improved spreading was accompanied by increased area of lamellar cytoplasm, increased number of focal contacts, and, in certain lines, by the appearance of actin bundles; numerous microtubules and intermediate filaments radiated from perinuclear zones into the lamellas of multinucleated cells. The number of cell-associated fibronectin fibrils was not increased by multinucleation. Cycloheximide did not prevent the improvement of spreading, suggesting that this effect was not due to any alterations of protein synthesis. Colcemid considerably decreased the effect of multinucleation but did not abolish it completely. It is suggested that increase of spreading is due to multinucleation-associated alterations of quantitative interrelationships between various cell components. One of these alterations is probably increased density of microtubules per unit length of outer cell edge.
Diffusion of a small molecule in the cytoplasm of mammalian cells.
Authors: Mastro A M , Babich M A , Taylor W D , Keith A D
Published: May 2006

Electron spin resonance was used to measure the diffusion of a small (Mr 170) spin label in the aqueous cytoplasm of mammalian cells. Translational and rotational motion were determined from the same spectra. Based on measurements made in model systems, it was hypothesized that calculations of the apparent viscosity from either rotational or translational motion would distinguish between the effects of cytoplasmic viscosity or cytoplasmic structure on diffusion. The diffusion coefficient calculated from spin label collision frequency, averaged 3.3 X 10(-6) cm2/sec in several cell lines. It was greater in growing cells and in cells treated with cytochalasin B than in quiescent cells. The viscosity of the cytoplasm calculated from the translational diffusion coefficient or the rotational correlation time was 2.0-3.0 centipoise (1 P = 0.1 Pa X sec), about 2-3 times that of the spin label in water. Therefore, over the dimensions measured by the technique, 50-100 A, solvent viscosity appears to be the major determinant of particle movement in cells under physiological conditions. However, when cells were subjected to hypertonic conditions, the translational motion decreased by 67%, while the rotational motion changed less than 20%. These data suggested that the decrease in cell volume under hypertonic conditions was accompanied by an increase in cytoplasmic barriers and a decrease in the spacing between existing components. In addition, a comparison of reported values for diffusion of a variety of molecules in water and in cells indicates that cytoplasmic structure plays an important role in the diffusion of proteins such as bovine serum albumin.
Appearance of cytotoxic antibody to viral gp70 on feline lymphoma cells (FL-74) in cats during ex vivo immunoadsorption therapy: quantitation, characterization, and association with remission of disease and disappearance of viremia.
Authors: Liu W T , Engelman R W , Trang L Q , Hau K , Good R A , Day N K
Published: May 2006

Fifty cats with feline leukemia virus (FeLV) infection and leukemia-lymphoma complex were treated by ex vivo immunoadsorption with Staphylococcus protein A-bound filters. Most cats responded to therapy. Twelve showed tumor regression, including disappearance of tumor cells, but died later of other complications. Three have had long-term remission of more than 1 year and remain healthy. A consistent finding in these three cats was the appearance during treatment of a complement-dependent cytotoxic antibody against cat lymphoma cells (FL-74). The cytotoxic antibody increased substantially during treatment. Appearance and increase of the cytotoxic antibody was associated with disappearance of FeLV from blood and remission of leukemia. By electroblot analysis, antibody to FeLV protein (Mr, 70,000) was detected in serum prior to detection of the cytotoxic antibody. The cytotoxic antibody was found by immunofluorescence to be specific for antigens on membranes of viable FL-74 cells. By using monoclonal antibodies to FL-74 cells and to components of FeLV, the cytotoxic antibody was shown to be directed against gp70, a glycoprotein of Mr 70,000, but not against p27 of FeLV or other membrane antigen(s) of FL-74 cells. The development of a high concentration of cytotoxic antibody to FeLV gp70 may play an important role in tumor regression and in disappearance of FeLV infection.
Streptokinase: cloning, expression, and excretion by Escherichia coli.
Authors: Malke H , Ferretti J J
Published: May 2006

Genomic DNA from Streptococcus equisimilis strain H46A was cloned in Escherichia coli by using the bacteriophage lambda replacement vector L47 and an in vitro packaging system. A casein/plasminogen overlay technique was used to screen the phage bank for recombinants carrying the streptokinase gene ( skc ). The gene was present with a frequency of 1 in 836 recombinants, and 10 independent clones containing skc were isolated and physically characterized. One recombinant clone was used to subclone skc in E. coli plasmid vectors. Plasmid pMF2 [10.4 kilobases (kb)] consisting of pACYC184 with a 6.4-kb H46A DNA fragment in the EcoRI site and pMF5 (6.9 kb) carrying a 2.5-kb fragment in the Pst I site of pBR322 were among the recombinant plasmids determining streptokinase production in three different E. coli host strains. Expression of skc was independent of its orientation in either vector, indicating that its own promoter was present and functional in E. coli. However, expression in pBR322 was more efficient in one orientation than in the other, suggesting that one or both of the bla gene promoters contributed to skc expression. Several lines of evidence, including proof obtained by the immunodiffusion technique, established the identity of E. coli streptokinase. Testing cell-free culture supernatant fluids, osmotic shock fluids, and sonicates of osmotically shocked cells for streptokinase activity revealed the substance to be present in all three principal locations, indicating that E. coli cells were capable of releasing substantial amounts of streptokinase into the culture medium.
Lotka's roots under rescalings.
Authors: Wachter K W
Published: May 2006

In the mathematical theory of stable populations, when the net maternity function is scaled by a constant divisor , changing its level without changing its shape, the rates of attrition of transient waves in the age structure of the population as it converges toward stability are altered. The attrition rates are specified by the real parts of the complex roots of Lotka 's equation. Conditions are given for the falsity of the longstanding claim that there always exists some rescaling that brings to zero the real part of the complex root governing the lowest frequency wave. A general account of scalable and unscalable roots follows for the discrete-age, Leslie formulation, elucidating and setting limits to the standard account of approach to stability.
Formation of termination-resistant transcription complex at phage lambda nut locus: effects of altered translation and a ribosomal mutation.
Authors: Warren F , Das A
Published: May 2006

Transcription antitermination by lambda N gene product is affected in a mutant Escherichia coli with altered ribosomal protein S10, caused by the nusE71 mutation. To study the role of translation in antitermination, we have fused the phage nutR locus, the site of action of N, with the lac regulatory region. We have monitored N action by measuring galactokinase, whose synthesis depends on suppression of terminators located between nutR and the galK cistron. We show that a deletion removing potential ribosome binding signals and AUG codons from the upstream region of nut site does not affect N action. Moreover, the lack of translation upstream of nutR does not overcome the antitermination defect caused by nusE mutation. When the upstream region is translated, however, N action is impaired if translation terminates 19 base pairs upstream of nutR . Termination of translation at further upstream sites, such as 23 or 97 base pairs upstream, does not interfere with N action. Our results suggest that the S10 ribosomal protein is required for N action without involving translation. These results also suggest that the nut site RNA itself plays an important role in the formation of a termination-resistant transcription complex.
Segmental homology and internal repetitiousness identified in putative nucleic acid polymerase and human hepatitis B surface antigen of human hepatitis B virus.
Authors: Ohno S
Published: May 2006

In a previous paper, it was argued that only those coding sequences descended from oligomeric repeats (the number of bases in the oligomeric unit not being a multiple of 3) can retain sufficiently long alternative open reading frames, and that such alternative open reading frames serve as the reservoir for the sudden generation of new polypeptide chains with novel functions. It was suggested that plasmid-encoded 6-amino hexanoic acid linear oligomer hydrolase that suddenly endowed Flavobacterium sp. K172 with the capacity to live off nylon by-products arose by the above mechanism. A corollary to the above argument is the expectation that those viral base sequences that are known to use two of the three alternative reading frames to encode two different polypeptide chains should invariably contain recognizable remains of the oligomeric tandem repeats, and as a consequence, various oligopeptidic repeats should also be present in the amino acid sequence of each. Furthermore, two polypeptide chains encoded by the same base sequence translated in different reading frames should show segmental homology of the type depicted previously. In the present paper, the base sequence of human hepatitis B virus ayw subtype that encodes an 832 amino acid residue long putative nucleic acid polymerase in one reading frame and a 226 residue long human hepatitis B surface antigen in the other reading frame was examined. All three predictions noted above were satisfied.
Chronic treatment with rabbit anti-mouse mu-chain antibody alters the characteristic immunoglobulin heavy-chain restriction of murine suppressor T-cell factors.
Authors: Sy M S , Lowy A , HayGlass K , Janeway C A , Gurish M , Greene M I , Benacerraf B
Published: May 2006

Prolonged treatment of mice, starting at birth, with rabbit anti-mouse mu-chain antibodies resulted in the elimination of immunoglobulin-bearing B cells in these animals. The ability of these animals to elicit antigen-specific delayed-type hypersensitivity or cytotoxic T-cell responses to azobenzenearsonate-coupled spleen cells was not impaired. The effect of anti-mu treatment on the restriction by immunoglobulin heavy-chain genes (Igh) of suppressor T cells was investigated. We found that first-order suppressor T-cell factor ( TsF1 ) obtained from anti-mu treated animals expresses an Igh restriction pattern distinct from that observed with TsF1 from normal untreated mice. Furthermore, TsF1 prepared from anti-mu treated animals did not express the major crossreactive idiotypic determinants normally present in TsF1 . The significance of these findings in relation to the role of immunoglobulin on the T-cell repertoire is discussed.
Dopamine receptor turnover rates in rat striatum are age-dependent.
Authors: Leff S E , Gariano R , Creese I
Published: May 2006

The time course of recovery of [3H]spiperone binding in the rat striatum after a single injection of the irreversible antagonist N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) shows that a slower rate of regeneration/turnover of D-2 dopamine receptors occurs in mid-life-mature versus young male rats. This slower receptor recovery reflects relatively slower rates of both receptor synthesis and degradation. Studies using cycloheximide indicate that protein synthesis plays a significant role in the reappearance of [3H]spiperone-binding sites. Other experiments indicate that chronic reserpine treatment, which produces dopamine receptor up regulation, also produces accelerated receptor recovery after EEDQ blockade. An age-related decline in dopamine receptor turnover, if present in humans and progressive into senescence, could be responsible for the increased risk of developing Parkinson disease and drug-induced parkinsonian-like extrapyramidal side effects with age. On the other hand, the more rapid receptor turnover rates seen in young rats may be a biochemical feature related to plasticity in the striatum during development.
Analysis of the transforming potential of the human H-ras gene by random mutagenesis.
Authors: Fasano O , Aldrich T , Tamanoi F , Taparowsky E , Furth M , Wigler M
Published: May 2006

Some tumor cells contain mutant ras genes that are capable of transforming NIH 3T3 cells. Those genes that have been analyzed arise from the wild-type, non-transforming ras genes by mutations producing single amino acid substitutions at position 12 or 61 of the encoded protein. We have performed random bisulfite-induced mutagenesis on the cloned wild-type human H-ras gene to find if mutations at other positions can activate the transforming potential of that gene. Most mutations are not activating, but mutations that specify single amino acid substitutions at position 12, 13, 59, or 63 of the encoded protein do activate the transforming potential of the H-ras gene. Some, but not all, mutant ras proteins show an altered electrophoretic mobility in NaDodSO4/polyacrylamide gels.
DNA sequence of the carA gene and the control region of carAB: tandem promoters, respectively controlled by arginine and the pyrimidines, regulate the synthesis of carbamoyl-phosphate synthetase in Escherichia coli K-12.
Authors: Piette J , Nyunoya H , Lusty C J , Cunin R , Weyens G , Crabeel M , Charlier D , Glansdorff N , Piérard A
Published: May 2006

The carAB operon of Escherichia coli K-12, which encodes the two subunits of carbamoyl-phosphate synthetase (glutamine hydrolyzing) [carbon-dioxide: L-glutamine amido-ligase (ADP-forming, carbamate-phosphorylating); EC 6.3.5.5], is cumulatively repressed by arginine and the pyrimidines. We describe the structure of the control region of carAB and the sequence of the carA gene. Nuclease S1 mapping experiments show that two adjacent tandem promoters within the carAB control region serve as initiation sites. The upstream promoter P1 is controlled by pyrimidines; the downstream promoter P2 is regulated by arginine. Attenuation control does not appear to be involved in the expression of carAB. A possible mechanism by which control at these promoters concurs to produce a cumulative pattern of repression is discussed. The translational start of carA is atypical; it consists of a UUG or AUU codon.
Detection of an Epstein-Barr virus-associated membrane antigen in Epstein-Barr virus-transformed nonproducer cells by leukocyte migration inhibition and blocking antibody.
Authors: Szigeti R , Sulitzeanu D , Henle G , Henle W , Klein G
Published: May 2006

Soluble membrane fractions derived from Raji cells trigger lymphocytes of Epstein-Barr virus (EBV)-seropositive, but not EBV-seronegative, individuals to release a lymphokine that inhibits leukocyte migration. The reaction can be blocked by the sera of patients with EBV-DNA-carrying tumors, Burkitt lymphoma, or nasopharyngeal carcinoma. Absorption of these sera with EBV-positive, but not EBV-negative, cells abrogates their blocking activity. These findings suggest that the antigen responsible for the leukocyte migration inhibition reaction is an EBV-encoded or an EBV-induced membrane component. The antigen is not identical with EBV-associated nuclear antigen or any other known antibody-detected EBV antigen.
Identification and mapping of polypeptides encoded by the P3HR-1 strain of Epstein-Barr virus.
Authors: Cohen L K , Speck S H , Roberts B E , Strominger J L
Published: May 2006

The Epstein-Barr virus (EBV)-specified polypeptides induced upon viral replication in the P3HR-1 cell line have been examined by immunoprecipitation with a high-titer human anti-EBV serum. Twenty-five predominant polypeptides were identified in cell extracts, whereas 18 polypeptides were precipitated from cell-free translation reactions directed by total mRNA. Hybrid selection of mRNA to the BamHI DNA clones of the EBV genome and immunoprecipitation of the corresponding cell-free translation products revealed 98 EBV-specified polypeptides and their coding location along the viral genome. In addition, the viral polypeptides that bind reversibly to DNA-cellulose have been characterized and the deduced map locations of this functional group of EBV-specified polypeptides is presented.
Biochemical evidence that secretor gene, Se, is a structural gene encoding a specific fucosyltransferase.
Authors: Kumazaki T , Yoshida A
Published: May 2006

Nonsecretors have no ABH blood group substances in their saliva and milk, but their erythrocytes contain the blood group substances. It has been generally believed that the secretor gene, Se, is a regulatory gene, not a structural gene, controlling the expression of (alpha 1----2)fucosyltransferase, which synthesizes the blood group H substance from its precursor, in secretions. To account for the existence of the blood type of "para Bombay" phenotype--i.e., H-negative in erythrocytes but H-positive in secretory fluids, another regulatory gene, Z, which would regulate the expression of the enzyme in the hematopoietic tissues, has been proposed. Contrary to this, a more simple model, in which the H gene and Se gene are both structural genes, encoding two separate fucosyltransferases in different tissues, was recently proposed. To settle the controversy, (alpha 1----2)fucosyltransferases were partially purified from human plasma and milk. The two enzymes differed from each other in the following respects: (i) the milk enzyme adsorbed to SP-Sephadex at pH 6.0, while the plasma enzyme did not; (ii) pH-activity profiles, with phenyl beta-D-galactoside as an acceptor, differed between the two enzymes; (iii) the milk enzyme exhibited lower thermal stability than the plasma enzyme; and (iv) Km values for several oligosaccharides with Gal(beta 1----3)GlcNAc and Gal(beta 1----4)GlcNAc as acceptors differed between the two enzymes. These results support the model that the Se gene is a structural gene encoding a distinctive (alpha 1----2)fucosyltransferase, refuting the classical regulatory gene model for the Se locus. The anomeric configuration of the fucosylated galactose residue produced by the action of enzyme was identified, thus establishing the specificity of the enzyme.
Purification and properties of branched-chain alpha-keto acid dehydrogenase phosphatase from bovine kidney.
Authors: Damuni Z , Merryfield M L , Humphreys J S , Reed L J
Published: May 2006

Branched-chain alpha-keto acid dehydrogenase (BCKDH) phosphatase was purified about 8000-fold from extracts of bovine kidney mitochondria. The highly purified phosphatase exhibited a molecular weight of approximately 460,000, as estimated by gel-permeation chromatography. Another form of the phosphatase, with an apparent molecular weight of approximately 230,000, was also detected under conditions of high dilution. In contrast to pyruvate dehydrogenase phosphatase, BCKDH phosphatase was active in the absence of divalent cations. BCKDH phosphatase was inactive toward 32P-labeled phosphorylase a, but exhibited approximately 10% maximal activity with 32P-labeled pyruvate dehydrogenase complex. BCKDH phosphatase activity was inhibited by GTP, GDP, ATP, ADP, UTP, UDP, CTP, and CDP. Half-maximal inhibition occurred at about 60, 200, 200, 400, 100, 250, 250, and 400 microM, respectively. These inhibitions were reversed completely by 2 mM Mg2+. GTP was replaceable by guanosine 5'-(beta, gamma-imido)triphosphate. GMP, AMP, UMP, CMP, NAD, and NADH showed little effect, if any, on BCKDH phosphatase activity at concentrations up to 1 mM. Heparin showed half-maximal inhibition at 2 micrograms/ml. This inhibition was only partially (30%) reversed by 2 mM Mg2+. CoA and various acyl-CoA compounds exhibited half-maximal inhibition at 150-300 microM. These inhibitions were not reversed by 2 mM Mg2+. BCKDH phosphatase activity was stimulated 1.5- to 3-fold by protamine, poly(L-lysine), and poly(L-arginine) at 3.6 micrograms/ml.
Identification of glucagon receptors in rat brain.
Authors: Hoosein N M , Gurd R S
Published: May 2006

The binding of radiolabeled glucagon to rat brain membranes was investigated. Regional distribution studies indicate higher specific binding of 125I-labeled monoiodoglucagon to olfactory tubercule, hippocampus, anterior pituitary, and amygdala membranes, with somewhat lower binding to membranes from septum, medulla, thalamus, olfactory bulb, and hypothalamus. 125I-labeled glucagon bound to rat brain synaptic plasma membrane fractions with high affinity (KD = 2.24 nM). Specific binding was greater to synaptosomal membrane fractions relative to myelin, mitochondrial nuclear, or microsomal fractions. Inclusion of 0.1 mM GTP in the binding assay reduced the glucagon binding affinity (KD = 44.5 nM). Several neuropeptides and other neuroactive substances tested did not affect binding of labeled glucagon to brain membranes. Three different glucagon analogs inhibited labeled glucagon binding. Synthetic human pancreatic growth hormone-releasing factor, hpGRF-44, also inhibited binding, although the concentration required for half-maximal displacement was 100-fold higher than for native glucagon. Addition of glucagon to brain membranes resulted in approximately equal to 3-fold maximal activation of adenylate cyclase over basal levels. Glucagon at a concentration of 4.74 nM was required for half-maximal activation of pituitary membrane adenylate cyclase. These findings provide evidence for rat brain binding sites that respond to the pancreatic form of glucagon and can transduce this binding into the activation of adenylate cyclase.
Identification of Epstein-Barr virus sequences that encode a nuclear antigen expressed in latently infected lymphocytes.
Authors: Hearing J C , Nicolas J C , Levine A J
Published: May 2006

The Epstein-Barr virus (EBV) BamHI restriction endonuclease fragment K (B95-8 strain) was introduced into a polyoma virus expression vector and used to transfect murine NIH 3T3 cells. An EBV-associated nuclear antigen was detected in these cells in an indirect immunofluorescence test using anti-EBV nuclear antigen-positive human sera. These sera recognized a Mr 88,000 polypeptide in 3T3 cells transfected with the BamHI fragment K-containing polyoma virus plasmid by radioimmunoelectrophoresis. A Mr 88,000 polypeptide also was detected in a B-cell line latently infected with the B95-8 strain of EBV. Plasmids containing insertion and deletion mutations in BamHI fragment K directed the synthesis of truncated forms of the Mr 88,000 polypeptide in 3T3 cells. These data directly demonstrate that the polypeptide identified in EBV-infected lymphocyte lines by anti-EBV nuclear antigen-positive human sera is encoded by the viral genome.
Fossil vertebrates from Antigua, Lesser Antilles: Evidence for late Holocene human-caused extinctions in the West Indies
Authors: Steadman David W. , Pregill Gregory K. , Olson Storrs L.
Published: May 2006

Vertebrate remains recovered from a limestone fissure filling on Antigua, Lesser Antilles, are associated with radiocarbon dates ranging from 4300 to 2500 yr B.P., contemporaneous with the earliest aboriginal human occupation of the island. Nine taxa of lizards, snakes, birds, bats, and rodents (one-third of the total number of species represented as fossils) are either completely extinct or have never been recorded historically from Antigua. These extinctions came long after any major climatic changes of the Pleistocene and are best attributed to human-caused environmental degradation in the past 3500 yr. Such unnatural influences have probably altered patterns of distribution and species diversity throughout the West Indies, thus rendering unreliable the data traditionally used in ecological and biogeographic studies that consider only the historically known fauna.
DNA sequence transfer between two high-cysteine chorion gene families in the silkmoth Bombyx mori.
Authors: Iatrou K , Tsitilou S G , Kafatos F C
Published: May 2006

We have previously shown that one type of high-cysteine silkmoth chorion protein (Hc-A) has evolved from the A family of chorion proteins by radical modifications of the NH2-terminal and COOH-terminal polypeptide arms: most of the arm sequences have been deleted, while short cysteine- and glycine-containing repeats have expanded into long arrays. Strikingly similar modifications of the arms have led to the evolution of a second type of high-cysteine protein (Hc-B) from the B family of chorion proteins. It appears that the parallel evolution of these high-cysteine-encoding gene families has not been entirely independent: examination of 3' untranslated regions shows evidence of information transfer between the two families.
Transformation of owl monkey T cells in vitro with Herpesvirus saimiri.
Authors: Rabin H , Hopkins R F , Desrosiers R C , Ortaldo J R , Djeu J Y , Neubauer R H
Published: May 2006

Owl monkey peripheral blood mononuclear cells were treated with phytohemagglutinin and expanded in interleukin 2 (IL-2)-containing medium. The cells were then exposed to Herpesvirus saimiri (HVS strain S295C)-infected owl monkey kidney monolayer cells. Four to 6 weeks later, the lymphocytes showed increased clumping and cell growth and the ability to grow in the absence of IL-2. Control lymphocyte cultures not exposed to HVS eventually died out at approximately 6-8 weeks, even in the presence of IL-2. Although infected lymphocytes grew continuously in the absence of IL-2, their growth was enhanced by addition of IL-2 to the cultures. Natural killer cell-like cytotoxicity and gamma-interferon release were also enhanced by IL-2. All cultures were positive for HVS antigens, infectious centers, or DNA. The reactivity of monoclonal antibodies to cell surface markers suggested that the resultant cell lines were comprised of activated T cells. The properties of the in vitro-transformed cells were similar to those of cells established from HVS-induced owl monkey tumors. Our results suggest that infection of T lymphocytes with HVS results in decreased dependence of T cells upon exogenous IL-2 for growth.
Spatial relationships of the human chorionic gonadotropin (hCG) subunits in the assembly of the hCG-receptor complex in the luteinized rat ovary.
Authors: Hwang J , Menon K M
Published: May 2006

In an attempt to examine the spatial relationships of the human chorionic gonadotropin (hCG) subunits in the assembly of the hCG-receptor complex, the recombined 125I-labeled hCG, with label in either the alpha subunit or the beta subunit, was cross-linked to the luteinizing hormone (LH)/hCG receptor. The efficacy of the cross-linking of the 125I-alpha subunit or the 125I-beta subunit of hCG to the LH/hCG receptor was then examined. The autoradiographic profile of 125I-hCG-receptor complex containing the label in the alpha subunit of hCG showed that the alpha subunit can cross-link with all four subunits of the LH/hCG receptor. However, only one faint labeled band, corresponding to Mr = 68,000, was detected when the 125I-hCG-receptor complex with label in the beta subunit was subjected to sodium dodecyl sulfate/polyacrylamide gel electrophoresis under reducing conditions. When the electrophoresis was performed under nonreducing conditions, the Mr 68,000 band disappeared concomitantly with the accumulation of radioactivity in the high molecular weight region. These results indicated that the beta subunit of hCG, unlike the alpha subunit, can cross-link only weakly with the smallest subunit of the LH/hCG receptor. A comparison of the differential effectiveness of the cross-linking of 125I-alpha subunit with 125I-beta subunit of hCG to the LH/hCG receptor suggests that both alpha and beta subunits of hCG are intimately associated with the receptor, but the bulk of the beta subunit of hCG is buried in between the receptor and the alpha subunit of hCG. On the basis of our data, a model for the spatial arrangement of hCG subunits in the hCG-receptor complex is proposed.
Intramolecular dislocation of the COOH terminus of the lac carrier protein in reconstituted proteoliposomes.
Authors: Carrasco N , Herzlinger D , Mitchell R , DeChiara S , Danho W , Gabriel T F , Kaback H R
Published: May 2006

A dodecapeptide corresponding to the carboxyl terminus of the lac carrier of Escherichia coli was synthesized, coupled to thyroglobulin, and the conjugate was used to generate site-directed polyclonal antibodies. The antibodies react with the carboxyl-terminal peptide and with the lac carrier protein, while monoclonal antibody 4B1 reacts with intact lac carrier protein, but not with the carboxyl-terminal peptide. Antibody 4B1 binds preferentially to right-side-out membrane vesicles relative to inside-out vesicles, confirming the presence of the 4B1 epitope on the periplasmic surface of the membrane. Alternatively, anti-carboxyl-terminal antibody binds preferentially to inside-out vesicles, demonstrating that the carboxyl terminus of the lac carrier protein is on the cytoplasmic surface. Surprisingly, both antibodies bind to proteoliposomes reconstituted with purified lac carrier protein, and quantitative binding assays indicate that the epitopes are equally accessible. When proteoliposomes containing purified lac carrier protein are digested with carboxypeptidases A and B, binding of anti-carboxyl-terminal antibodies decreases by greater than 80%, while binding of antibody 4B1 and various transport activities remain essentially unchanged. It is suggested that during reconstitution, the lac carrier protein undergoes intramolecular dislocation of the carboxyl terminus with no significant effect on its catalytic activity.
RecA-independent recombination at gamma delta termini and at IS3 producing inverted repetition in F' plasmids.
Authors: Tsai M , Thompson T L , Deonier R C
Published: May 2006

Two F' plasmids isolated independently from a recA- strain of Escherichia coli and containing identical deletion end points and identical associated inverted duplications are described. In these plasmids, DNA of F plasmid from the IS3 element alpha 1 beta 1 up to the transposon gamma delta is duplicated in inverted orientation, and a 63-kilobase-pair segment from the chromosomal DNA of the plasmid is deleted. One deletion terminus is the chromosomal IS3 alpha 4 beta 3 carried by the parental plasmid, ORF203. It is proposed that these structures resulted from interduplex strand exchanges that occurred at the ends of the movable element gamma delta and at IS3. This indicates that the 35-base-pair gamma delta termini can participate in genome rearrangements by mechanisms that are distinct from complete transposition mechanisms.
The heterogeneity and functional capacities of human thymocyte subpopulations.
Authors: Gelin C , Boumsell L , Dausset J , Bernard A
Published: May 2006

Analysis of human thymocytes with monoclonal antibodies belonging to five distinct clusters of differentiation (CD1, CD3-CD5, CD8) revealed a high degree of phenotypic heterogeneity. Six subpopulations could be defined in the thymic compartment characterized by the presence of CD1 antigens (cortical type); four subpopulations could be defined in the compartment characterized by the lack of CD1 but by the presence of CD5 antigens (medullary type); two subpopulations could be defined in the compartment characterized by the lack of both CD1 and CD5 antigens. Thymic samples could be categorized as either high responder or low responder to phytohemagglutinin alone. The defect of low responders was, to a large extent, attributable to a lack of interleukin 2 availability in the medullary type compartment. Yet, cortical-type subpopulations, both from high and low responders, were able to respond to phytohemagglutinin alone to the same extent. Undesirable cell contamination was excluded by limiting dilution analysis. Moreover, cortical-type cells were found to be able to respond to concanavalin A alone, while medullary-type cells and total populations did not respond to concanavalin A alone. Thus, the human thymus includes a number of cell subpopulations involved in complex functional interactions.
A cDNA clone encoding neuropeptides isolated from Aplysia neuron L11.
Authors: Taussig R , Kaldany R R , Scheller R H
Published: May 2006

Single nerve cells can use more than one substance as extracellular chemical messengers. Classical transmitters have been shown to coexist in the same neuron and possibly even in the same vesicle as neuroactive peptides. Furthermore, multiple neuroactive peptides, which are thought to be coreleased, are often encoded in the same precursor assuring stoichiometric synthesis. The precise organization of multiple message systems and the physiological significance of the coexistence is poorly understood. The abdominal ganglion of the gastropod mollusc Aplysia contains a number of identified neurons that are cotransmitter candidates. One such cell, L11, is cholinergic and probably also uses biologically active peptides. Differential screening with labeled cDNA was used to isolate cDNA clones expressed specifically in the bag cells and abdominal ganglion neurons L11 or R15. Analysis of an L11-specific clone suggests that it encodes a 14.7-kDa protein that is the precursor for the secreted peptides. The poly(A)+ RNA transcript is approximately equal to 1.2 kilobases and there are 1-3 copies of this gene in the Aplysia haploid genome.
Tonically discharging putamen neurons exhibit set-dependent responses.
Authors: Kimura M , Rajkowski J , Evarts E
Published: May 2006

Previous microelectrode recordings in the putamen of monkeys have revealed a class of tonically active neurons without apparent behavioral correlates. The present study shows that such neurons have responses to stimuli that trigger movement but that these responses disappear when motor responses to the stimuli are extinguished. The short latency of the responses (less than for other putamen neurons) suggests that they may play a role in linking conditioned stimuli and responses.
Early origin and pervasiveness of cellular heterogeneity in some malignant transformations.
Authors: Rubin H
Published: May 2006

Nontransformed BALB/3T3 cells were passaged weekly in monolayer culture on plastic dishes and aliquots were regularly assayed for colony production when suspended in agar. During several months of passaging, a single large colony arose once in the agar assay, and its constituent cells were isolated to form a subline of transformed cells. These cells had the fusiform and rounded morphologies characteristic of transformed cells and had a colony-forming efficiency in agar (CFEag) of approximately 10%. Five of the agar colonies were isolated at random and the cell populations of these primary subclones were further analyzed. Four of the five subclonal populations differed from each other in appearance slightly, but consistently, while the fifth had a markedly different colonial morphology. They also differed from one another in CFEag as well as in average diameter of the agar colonies. These general differences among the five subclones remained, although the CFEag and colony sizes changed recognizably in repeated weekly transfers. All of the subclones produced sarcomas in nude mice but did so at different rates. A secondary generation of five subclones was derived from each of three of the original subclonal populations. All the secondary subclones had the same morphology as the primary subclones from which they were derived. The averages of the CFEag and colony sizes of the secondary subclones from each of the subclones differed as a group from the other groups, but they also differed, to a lesser extent, among themselves. Despite the differences noted among the primary subclones in morphology, growth in agar, and tumor production in mice, they were virtually identical in their rapid growth rate on a plastic surface and all shared a high rate of glucose consumption. A second transformed clone arose among the continuously passaged nontransformed cells 5 months after the first one had appeared. Subclones of this clone did not differ recognizably from one another in morphology or in CFEag. The results indicate that recognizable heterogeneity can arise in some tumors during the earliest stages of their development and involve a high proportion of their constituent cells, while it may not become evident in other tumors until much later.
Cross-reactions of polysaccharides of fungi, molds, and yeasts in anti-pneumococcal and other antisera.
Authors: Heidelberger M , Bernheimer A W
Published: May 2006

Cross-reactions of a number of glycans and polysaccharides isolated from fungi, molds, and yeasts in anti-pneumococcal and other antisera are tabulated and discussed insofar as possible with relation to the chemical structures of the cross-precipitating substances and the polysaccharidic antigens giving rise to the reactive antibodies. For example, the slime of Physarum polycephalum precipitated antisera to pneumococcal type 4 and Klebsiella type K1. The polysaccharides of type 4 and K1 contain pyruvic acid in acetal linkage on hydroxyls 2 and 3 of sugars. Therefore, pyruvic acid was looked for and found in Physarum slime. Numerous other relations between chemical structure and immunological specificity are given.
On stabilization of the solutions of parabolic equations with small parameter
Authors: Freidlin M. I.
Published: May 2006

We consider two classes of quasi-linear parabolic equations depending on a small parameter ε. The asymptotic behavior of the solutions as
t
→ α and ε → 0 is investigated by studying the associated Markov family. We find its dependence on the way
t
and ε
-1
go to infinity and on the initial point.
The cloned genome of ground squirrel hepatitis virus is infectious in the animal.
Authors: Seeger C , Ganem D , Varmus H E
Published: May 2006

The lack of an in vitro infectivity assay for hepatitis B viruses has impeded the analysis of their genetic organization. To examine the feasibility of generating mutant and recombinant viruses after manipulation of cloned viral DNA in vitro, we have tested the infectivity of the cloned genome of ground squirrel hepatitis virus (GSHV) in virus-free Beechey ground squirrels. We demonstrate that cloned GSHV DNA is infectious when injected directly into the liver in the form of trimeric, head-to-tail recombinant clones and recircularized monomeric molecules but not when injected into the portal vein. Infections established in all four recipients of intrahepatic injections of cloned GSHV DNA exhibited the characteristics observed after administration of virus: GSHV surface antigen and viral DNA appeared in the serum 14-22 weeks after inoculation, and both circular and heterogeneous protein-linked forms of viral DNA were found in liver biopsy samples. Furthermore, virus present in the sera of these animals can be transmitted to other ground squirrels. These findings imply that any function of virion proteins in the initiation of infection by hepatitis B viruses can be bypassed with the use of cloned viral DNA and that this animal model is suitable for testing mutant genomes.
Antibodies to two defined regions of the transforming protein pp60src interact specifically with the epidermal growth factor receptor kinase system.
Authors: Lax I , Bar-Eli M , Yarden Y , Libermann T A , Schlessinger J
Published: May 2006

Antibodies generated against two synthetic peptides corresponding to two defined regions on the transforming protein of Rous sarcoma virus, pp60src, interact specifically with the epidermal growth factor (EGF)-receptor kinase. An antibody directed against a synthetic peptide corresponding to the major phosphorylation site of pp60src interacts specifically with EGF receptor and immunoprecipitates a functional EGF-receptor kinase. The second antibody, which binds close to a region on the src molecule that is required for its kinase activity, also binds to EGF-receptor kinase and prevents the autophosphorylation of the receptor molecules. Neither antibody binds to intact cells, but they do recognize various forms of the solubilized receptor. It is concluded that at least two cytoplasmic domains of the EGF receptor are antigenically and presumably also structurally related to specific domains on pp60src.
Isolation of an active transcription initiation complex from HeLa cell-free extract.
Authors: Tolunay H E , Yang L , Anderson W F , Safer B
Published: May 2006

A two-step procedure has been developed for the formation of RNA polymerase II transcription initiation and elongation complexes. Initiation complexes are rapidly formed in HeLa cell-free extract supplemented with a DNA template containing the adenovirus 2 major late promoter and ATP. Assembly of transcription components required for correct initiation is absolutely dependent on specific eukaryotic promoter sequences. Sarkosyl-sensitive transcription initiation complexes are rapidly converted to Sarkosyl-resistant elongation complexes when supplemented with the remaining nucleoside triphosphates. The 60S initiation complex can be extensively purified by glycerol gradient centrifugation and is easily separated from free RNA polymerase II and free DNA template. Recovery of this stable complex is greater than 90%. Specific transcription cannot be detected if the DNA template is subsequently added to gradient fractions containing HeLa cell-free extract components alone. This suggests that the DNA templates promote the specific assembly of RNA polymerase II and transcription factors required for accurate initiation. Since conversion of purified initiation complexes to elongation complexes can occur without additional HeLa cell components, the presence of transcription components required for initiation and elongation in a single complex is indicated.
Leukotriene B4 mobilizes calcium without the breakdown of polyphosphoinositides and the production of phosphatidic acid in rabbit neutrophils.
Authors: Volpi M , Yassin R , Tao W , Molski T F , Naccache P H , Sha'afi R I
Published: May 2006

The addition of fMet-Leu-Phe, leukotriene B4, or arachidonic acid to rabbit neutrophils causes a rise in the level of intracellular free calcium as measured by the fluorescent dye quin-2. The calcium response is rapid and dose-dependent with an ED50 of 0.12 +/- 0.05 nM for leukotriene B4, 0.20 +/- 0.02 nM for fMet-Leu-Phe, and 320 +/- 30 nM for arachidonic acid. However, unlike fMet-Leu-Phe, leukotriene B4 at concentrations up to 70 nM does not cause a significant breakdown of any of the phosphoinositides or the generation of phosphatidic acid, arachidonic acid, or 1,2-diacylglycerol. The addition of arachidonic acid causes little (less than 20%) production of phosphatidic acid. Furthermore, the dose-response curve of the generation of phosphatidic acid by fMet-Leu-Phe is shifted to the right when compared with that for calcium mobilization. The results reported here indicate that, although similar in many respects, there are important qualitative differences between the mechanisms of action of these two chemotactic factors. They also show that calcium mobilization by leukotriene B4 is not mediated by the breakdown of any of the phosphoinositides, and calcium mobilization by leukotriene B4, arachidonic acid, and possibly fMet-Leu-Phe is not mediated by the generation of phosphatidic acid.
Localization of a fibrin gamma-chain polymerization site within segment Thr-374 to Glu-396 of human fibrinogen.
Authors: Horwitz B H , Váradi A , Scheraga H A
Published: May 2006

Fibrinogen fragment D1 was converted to fragment D3 by plasmic digestion. This conversion eliminates the ability of the fragment to interact with thrombin-exposed sites on fibrin monomer. Peptides released during this plasmic digestion were assayed for the presence of a polymerization site by affinity chromatography on fibrin monomer-Sepharose. We found that a 33-residue peptide, corresponding to gamma-chain Thr-374 to Lys-406, binds to immobilized fibrin monomer. This peptide is a shorter variant of a previously isolated 38-residue peptide (gamma-chain Thr-374 to Val-411) that contains a polymerization site [Olexa, S. A. & Budzynski, A. Z. (1981) J. Biol. Chem. 256, 3544-3549]. The peptide mixture derived from fragment D1 was digested further with Staphylococcus aureus protease V8, and a 23-residue peptide, gamma-chain Thr-374 to Glu-396, carrying a polymerization site, was isolated by affinity chromatography. This 23-residue peptide inhibits the polymerization of desA-fibrinogen. We conclude that a polymerization site complementary to the site exposed by removal of fibrinopeptide A is present in this segment. The localization of the polymerization site within the gamma-chain segment 374-396 implies that the polymerization site does not overlap with segments of the gamma-chain that are responsible for platelet aggregation and for Staphylococcus clumping (residues 400-411 and 397-411, respectively) or with the residues involved in factor XIIIa-catalyzed fibrin crosslinking (Gln-398 and Lys-406).