bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of rat monoclonal antibodies to epitopes encoded by the viral oncogene (v‐fms) of McDonough feline sarcoma virus
Authors: Anderson Soni J. , Furth Mark E. , Wolff Linda , Ruscetti Sandra K. , Sherr Charles J. 
Published: December 2004

AbstractThe McDonough strain of feline sarcoma virus (SM‐FeSV) contains a viral oncogene, v‐fms, transduced from cat cellular genetic sequences designated c‐fms. Monoclonal antibodies reactive to antigenic determinants encoded by v‐fms were prepared by immunizing rats with live, syngeneic SM‐FeSV‐transformed cells, and fusing splenic lymphocytes from a tumor‐bearing animal with cultured rat myeloma cells. Culture supernatants from hybrids producing antibodies to epitopes encoded by v‐fms were identified by immunoprecipitation of radiolabeled polypeptides from SM‐FeSV‐transformed mink cells. Four positive hybrids were cloned twice in soft agar, established as stable lines, and grown in defined serum‐free medium to facilitate purification of homogeneous antibodies. The monoclonal antibodies were used to assay SM‐FeSV‐specific products by “immunoblotting” of elcctrophoretically separated proteins, and by fixed‐cell immunofluorescence.
Genetic recombination in avian retroviruses
Authors: Skalka A. M. , Boone L. , Junghans R. , Luk D. 
Published: December 2004

AbstractThe avian retroviruses—and probably other retroviruses as well—undergo a variety of recombinational events with relatively high efficiency. An understanding of the molecular basis of these events should provide insight into the important biological properties these agents exhibit when they become integrated into somatic or germ‐line host cells, when they exchange genetic information among themselves, or when they transduce host cell genes. In this article we review molecular models for homologous recombination, against a background of the other types of recombination events that arc typical of these viruses. It seems probable that the retroviruses will provide useful models for analysis of a variety of DNA rearrangements known to occur in eukaryotic cells.
Regulation of herpes simplex virus gene transcription in vitro
Authors: Beck Thomas W. , Millette Robert L. 
Published: December 2004

AbstractWe used partially purified RNA polymerase II from uninfected (Pol II) and from herpes simplex virus type 1 (HSV‐1) infected HEp‐2 cells (Pol II‐H) to transcribe HSV‐1 DNA in vitro. Gel electrophoretic analysis of the products produced from native HSV‐1 DNA yielded weight average chain lengths of 4.0 and 3.5 kb for the Pol II and Pol II‐H products, respectively. Blot hybridization analyses of the HSV DNA transcripts showed that both enzymes transcribed RNA from essentially all regions of the genome. However, Pol II preferentially transcribed regions coding for the immediate‐early or alpha mRNAs, whereas Pol II‐H preferentially copied regions coding for the early (β) and late (γ) gene products. Transcriptional analyses of the cloned HSV‐1 Bam HI‐Q fragment (containing the thymidine kinase (TK) gene) and its subfragments showed that (1) the major transcripts produced by Pol II‐H were distinctly different from those produced by Pol II; (2) Pol II and Pol II‐H utilized different promoters for the synthesis of major transcripts; (3) both enzymes produced three minor transcripts that were partially overlapping and in opposite direction to the TK gene; and (4) only Pol II‐H initiated transcription from the TK promoter. In contrast, both Pol II and Pol II‐H generated an identical set of transcripts from an adenovirus 2 early region DNA fragment. The sizes of the products suggest that RNA processing may be occurring in vitro. These results show that HSV‐1 infection alters the in vitro transcriptional specificity of RNA polymerase II and demonstrate that this system should be useful for studying in vitro the regulation of gene transcription.
Analysis of v‐mos encoded proteins in cells transformed by several related murine sarcoma viruses
Authors: Papkoff Jackie , Lai Mei H.‐T. , Hunter Tony 
Published: December 2004

AbstractWe have used antisera against synthetic peptides to identify and characterize a 37,000 dalton v‐mos encoded protein (p37mos) in cells transformed by M‐MuSV 124. p37mos, a phosphoprotein, comprises only about 0.0005% of total cellular protein in cell lines transformed by M‐MuSV 124. NIH 3T3 cells acutely infected with M‐MuSV 124, however, contain 30–100‐fold more p37mos. These elevated levels of p37mos correlate with striking morphological changes and cell death in the acutely infected cell population. Using the antipeptide antisera, we have extended the analysis of v‐mos proteins to include several other MuSV variants that contain a similar v‐mos gene to M‐MuSV 124. With the exception of P85, the gag‐mos fusion protein from ts110 MuSV, the v‐mos gene of these variants is expressed as a 35,000–37,000 dalton protein (size depending on the particular virus).
Epidermal growth factor stimulates fluid phase endocytosis in human fibroblasts through a signal generated at the cell surface
Authors: Wiley H. Steven , Cunningham Dennis D. 
Published: December 2004

AbstractWe have investigated the stimulation of fluid phase endocytosis by epidermal growth factor (EGF) in normal human fibroblasts using 125I‐labeled polyvinylpyrrolidone (125I‐PVP) as a fluid phase marker. We found that EGF initially induced a thereefold increase in the rate of 125I‐PVP uptake. This initial burst of fluid uptake terminated within 10 min. Thereafter, the rate of fluie uptake in EGF‐treated cells was approximately 40% higher than in control cells. To identify the cellular site of EGF action in stimulating fluid phase endocytosis, we examined the kinetics of the induction of this response as well as the kinetics of cell surface binding and internalization of 125I‐EGF. Although there was no detectable lag between binding of EGF to the cell surface and its internalization, the kinetics of the two processes were quite different. Significantly, the kinetics of induction of 125I‐PVP uptake matched the kinetics of binding of 125I‐EGF to its cell surface receptors, indicating that the signal for the increase in fluid phase endocytosis is generated at the cell surface. To determine if EGF‐stimulated fluid phase endocytosis was related to EGF‐stimulated endocytosis of its own receptor, we compared the EGF dose dependency and time course of the two processes. Although the stimulated endocytosis of the EGF receptor was not saturable with respect to the concentration of EGF used, the stimulation of fluid phase endocytosis was half maximal at an EGF concentration of 1 ng/ml and saturated at a concentration of 5 ng/ml. Also, the stimulation of fluid phase endocytosis was sevenfold greater initially after adding EGF than after a 30‐min continuous incubation with the hormone, whereas the enhanced clearance of the EGF receptor did not change during this time period. We conclude that the EGF‐stimulated increase in fluid phase endocytosis is not directly coupled to EGF‐stimulated endocytosis of its own receptor but instead to a separate signal generated at the cell surface.
Fibronectin is apparently not involved in species‐specific reaggregation of cells from the marine sponge geodia cydonium
Authors: Conrad J. , Diehl‐Seifert B. , Zahn R. K. , Uhlenbruck G. , Zimmermann E. , Müller W. E. G. 
Published: December 2004

AbstractExperiments were carried out to test the hypothesis that fibronectin is involved in reaggregation of dissociated sponge cells. Cells from the siliceous sponge Geodia cydonium were extracted with urea to solubilize fibronectin from cells of higher multicellular organisms. The crude extract was further fractionated by DNA, heparin, and collagen affinity chromatography; they were termed Geodia fibronectinlike fractions. The fibronectinlike fractions contained a series of proteins with molecular weights different from that of the genuine fibronectin. The Geodia fibronectinlike fractions did not react with antiserum, produced against human fibronectin, under formation of a precipitin line. Using this antiserum the sponge cells could not be specifically labeled with FITC‐anti‐IgG antiserum. Radioimmunoprecipitation experiments revealed that the Geodia fractions contain—if at all—0.1% fibronectin or fibronectinlike protein at the most. In the crucial experiments it was shown that the Geodia fibronectinlike fractions, human fibronectin, and antifibronectin antiserum exerted no influence on adhesion of Geodia cells either in the absence or in the presence of the soluble aggregation factor. Based on these findings, we conclude that fibronectin is apparently not present on Geodia cells and does not play a role in aggregation of this biological system.
Activation of the glucocorticoid–receptor complex
Authors: Schmidt Thomas J. , Barnett Carol A. , Litwack Gerald 
Published: December 2004

AbstractA crucial step in the interaction of glucocorticoids with target cells is the activation step, which involves a conformational change in the cytoplasmic glucocorticoid–receptor protein complexes and facilitates their binding to the cell nucleus. Activation can be quantified by measuring the ability of glucocorticoid‐receptor complexes to bind to polyanions, such as DNA‐cellulose, and unactivated complexes can be separated from activated complexes by rapid ion exchange chromatography using diethylaminoethyl (DEAE)‐Sephadex or DEAE‐cellulose. Activation occurs in vivo under physiological conditions and the rate of activation of cytoplasmic glucocorticoid–receptor complexes can be enhanced in vitro by physical manipulations (elevated temperature, increased ionic strength, dilution). In vitro studies suggest that activation is a regulated process and a low molecular weight component termed modulator, which has been identified in rat hepatic cytosol, inhibits activation. Additional studies employing phosphatase inhibitors, such as molybdate, and purified calf intestinal alkaline phosphatase suggest that either the receptor protein or a regulatory component is dephosphorylated during activation. Results obtained with specific chemical probes suggest that activation results in the exposure of basic amino acid residues consisting minimally of lysine, arginine, and histidine. Pyridoxal 5′‐phosphate, a specific probe for lysine residues, exerts dual effects on glucocorticoid‐receptor complexes, since it stimulates the rate of activation and also inhibits the binding of previously activated complexes to nuclei or DNA‐cellulose. The ability of 1,10‐phenanthroline, a metal chelator, to inhibit the DNA‐cellulose binding of activated complexes suggests that a metal ion(s) located at or near the DNA binding site may become exposed as a consequence of activation. Collectively, the results of these various experiments suggest that activation is a regulated biochemical phenomenon with physiological significance.
Nucleotide sequence and organization of the transforming region and large terminal redundancies (LTR) of avian myeloblastosis virus (AMV)
Authors: Papas Takis S. , Rushlow Keith E. , Watson Dennis K. , Lautenberger James A. , Perbal Bernard , Baluda Marcel E. , Reddy E. Premkumar 
Published: December 2004

AbstractAvian mycloblastosis virus (AMV) is a replication‐defective acute leukemia virus, requiring a helper virus to provide the viral proteins essential for synthesis of new infectious virus. The genome of the AMV has undergone a sequence substitution in which a portion of the region normally coding for the “env” protein has been replaced by chicken cellular sequences. These latter sequences are essential for the transforming activity of the virus. We have determined the complete nucleotide sequence of this region. Examination of the AMV oncogenic sequence revealed an open reading frame starting with the initiation codon ATG within the acquired cellular sequences and terminating with the triplet TAG at a point 33 nucleotides into helper viral sequences to the right of helper‐viral‐cellular junction. The stretch of 795 nucleotides would code for a protein of 265 amino acids with a molecular weight of 30,000 daltons. The eleven amino acids at the carboxy terminus of such a protein would be derived from the env gene of helper virus.
Ultrastructural and biochemical identification of con A receptors in the desmosome
Authors: Shida Hisato , Gorbsky Gary , Shida Mariko , Steinberg Malcolm S. 
Published: December 2004

AbstractCorrelated ultrastructural and biochemical methods were used to identify and localize Concanavalin A (Con A) receptors in the desmosomes of bovine epidermis. Specific carbohydrate residues were labeled with ferritin‐Con A in thin sections of tissue embedded in a hydrophilic resin. Quantitative mapping of ferritin distribution in labeled desmosomes revealed that Con A receptors are localized in the intercellular zone and concentrated along the desmosomal midline or central dense stratum. Labeling was almost entirely absent when sections were treated with ferritin‐Con A in the presence of 0.1 M α‐methyl mannoside, a hapten‐inhibitor of Con A. “Whole” desmosomes and desmosomal intercellular regions (desmosomal “cores”) were purified from bovine muzzle epidermis. Sodium dodecyl sulfate (SDS)‐polyacrylamide gel electrophoresis reveals a limited number of major desmosomal protein constituents. Certain of these are glycoproteins and are greatly enriched in the core fraction. Almost all the desmosomal glycoproteins are intensely labeled when electrophoretic gels of whole desmosome or core fractions are exposed to fluorescent Concanavalin A.
A monoclonal antibody to the human epidermal growth factor receptor
Authors: Waterfield Michael D. , Mayes Elaine L. V. , Stroobant Paul , Bennet Paul L. P. , Young Susan , Goodfellow Peter N. , Banting George S. , Ozanne Bradford 
Published: December 2004

AbstractA monoclonal antibody of the IgG class, EGFR1, has been isolated using cells of the epidermoid carcinoma line A431 as immunogen. The A431 antigen recognized by EGFR1 has an apparent molecular weight of approximately 175,000, is a cell‐surface molecule which can be specifically cross‐linked to EGF, exhibits an EGF‐stimulated protein kinase activity, binds to EGFR1 in a number of human cell lines to a degree which parallels EGF binding, and shows EGF‐dependent internalization in A431 cells and human fibroblasts. We therefore conclude that EGFR1 is directed against an antigenic site on the human EGF receptor. EGFR1 is not mitogenic for human fibroblasts and does not inhibit EGF binding under a variety of assay conditions. The characterization of EGFR1 has allowed the unambiguous assignment of the structural gene for the human EGF receptor to chromosome 7. Preliminary results suggest that a convenient method for isolating a range of anti‐EGF receptor monoclonal antibodies can be developed, based on a hybridoma supernatant screening assay in which positive supernatants bind selectively to a human‐mouse cell hybrid containing human chromosome 7.
Butyrate‐induced histone hyperacetylation in human and mouse cells: estimation of putative sites of histone acetylation in vivo
Authors: Pantazis Panagiotis , Bonner William M. 
Published: December 2004

AbstractHuman and mouse cells in culture were treated with various concentrations of sodium butyrate. Acid‐extracted histones of control and butyrate‐treated cells were analyzed by two‐dimensional gel electrophoresis. All core histones of the control cells contained modified forms. All core histones of the butyrate‐treated cells were hyperacetylated. Depending on the number of acetylation sites per molecule, each histone or histone variant exhibited a characteristic number of acetylated forms. This number was the same for each histone common in human and mouse cells treated with butyrate. Histones 2A.1, 2A.2, and 2A.X have two sites of inner acetylation; 2A.Z has 3; 2B's have 5; and each one of the H3 variants as well as H4 have 4.
Ecdysteroid binding activity in embryos of drosophila melanogaster
Authors: Osterbur David L. , Yund Mary Alice 
Published: December 2004

AbstractEcdysteroid binding proteins have been found in nuclei of Drosophila melanogaster embryos. Comparison of results derived from Scatchard analysis, analogue binding competition, and sucrose gradient centrifugation has revealed no significant differences between the properties of the putative embryonic receptor and those of the receptor found in imaginal disks or Kc cells.
Localization and characterization of phosphorylation sites of the fujinami avian sarcoma virus and prcii virus transforming proteins
Authors: Weinmaster Gerry , Pawson Tony 
Published: December 2004

AbstractFujinami sarcoma virus (FSV) and PRCII are avian sarcoma viruses which share cellularly derived v‐fps transforming sequences. The FSV P140gag‐fps gene product is phosphorylated on three distinct tyrosine residue's in transformed cells or in an in vitro kinase reaction. Three variants of FSV, and the related virus PRCII which lacks about half of the v‐fps sequence found in FSV, encode gene products which are all phosphorylated at tyrosine residues contained within identical tryptic peptides. This indicates a stringent conservation of amino acid sequence at The tyrosine phosphorylation sites which presumably reflects the importance of these sites for the biologic activity of the transforming proteins. Under suitable conditions the proteolytic enzymes p15 and V8 protease each introduce one cut into FSV P140, p15 in the N‐terminal gag‐encoded region and V8 protease in the middle of the fps‐encoded region. Using these enzymes we have mapped the major site of tyrosine phosphorylation to the C‐terminal end of the fps region of FSV pl40gas‐fps. A second tyrosine phosphorylation site is found in the fps region of FSV P140 isolated from transformed cells, and a minor tyrosine phosphorylation site is found in the N‐terminal gag‐encoded region. Our results suggest that the C‐terminal fps‐encoded region is required for expression of the tyrosine‐specific protein kinase activity.
Monoclonal antibodies to feline sarcoma virus gag and fes gene translational products
Authors: Veronese Fulvia , Kelloff Gary J. , Reynolds Fred H. , Hill Richard W. , Stephenson John R. 
Published: December 2004

AbstractA series of hybridomas have been isolated which produce monoclonal antibodies directed against polyprotein gene products of the Gardner, Snyder‐Theilen, and McDonough strains of FeSV. Within these are representatives of several immunoglobulin classes including IgG1, IgG2a, IgG2b, IgG2c, and IgM. Antibody produced by one hybridoma recognizes immunologic determinants localized within an FeLV gag gene structural component (p15) common to polyproteins encoded by all three FeSV isolates whereas antibody produced by a second is specific for p30 determinants unique to P170gag‐fms. Additional hybridomas secrete antibody directed against v‐fes‐encoded determinants common to the Gardner and Snyder‐Theilen FeSV‐encoded polyproteins. GA P110gag‐fes and ST P85gag‐fes immunoprecipitated by antibody directed against p15 exhibit tyrosine‐specific protein kinase activity but lack such activity when precipitated by antibody specific for their acquired sequence (v‐fes) components.
Oligodeoxynucleotide base recognition by steroid hormone receptors
Authors: Kumar S. Anand , Beach Thaisa A. , Dickerman Herbert W. 
Published: December 2004

AbstractOligodeoxynucleotides covalently linked to cellulose were used as probes of the DNA‐binding domains of mouse steroid holoreceptors. With uterine cytosol estrogen receptor (E2R) the relative binding order, in prior studies, was oligo(dG) > oligo(dT) ≧ oligo(dC) > > oligo(dA) > oligo(dI). The binding reactions were salt‐sensitive with an optimal KCl concentration of 0.1–0.2 M. There was no enhancement of binding by activation, either temperature‐ or salt‐induced. In the present study, using the oligomer ligands at a lower concentration, oligo(dT) binding was greater than that to oligo(dC). Quantitative differences in oligodeoxynucleotide binding were elicited by a number of inhibitors. These differences are again seen by exposure of E2R to chaotropic salts such as SCN−, ClO4− and NO3− as well as to putative modifiers of receptor amino acids, ie, iodoacetamide, 1,2 cyclohexanedione, and Rose Bengal. These results, and the quantitative differences following heat and purification, led to a designation of two types of subsites within the DNA‐binding domain of uterine E2R. These are stable G sites, which interact with oligo(dG); and labile N sites, which bind to oligo(dT), oligo(dC) and oligo(dA). Stimulation of binding to N sites and stabilization of the holoreceptor was effected by histones H2A and H2B. However, the differential response to incubation at 37°C was not altered by addition of H2B. Treatment of uterine E2R by limited proteolysis also eliminated the stimulatory response to H2B. The above data, as well as prior studies, indicate that steroid holoreceptors can discriminate between the structural features of deoxynucleotide bases and this recognition process can be modulated by accessory proteins.
Normal mouse serum contains peptides which induce fibroblasts to grow in soft agar
Authors: Rapp U. R. , Gunnell M. , Marquardt H. 
Published: December 2004

AbstractThe untransformed mouse fibroblast cells NIH/3T3, C3H/10T1/2, and rat NRK cells do not grow in soft agar in medium supplemented with 10% fetal calf serum. When fetal calf serum in the growth medium was supplemented with less than 1% of sera from mice or other vertebrates, however, these cells responded, forming large colonies. The morphology of soft agar colonies was a function of the treated cell type. In the presence of 10% serum from C57BL/6 mice, NRK cells grew to smooth‐surfaced spherical colonies, while NIH/3T3 colonies showed individual round cells on their surface and C3H/10T1/2 cells grew as extended cells forming columns of end to end connected fibroblasts. Mus Musculus Castaneus‐Epithelial (MMC‐ E) cells were not stimulated to grow in soft agar under these conditions. The major fibroblast colony‐inducing factor (F‐CIF) was partially purified from mouse serum by acid/ethanol‐extraction, gel permeation chromatography, and reverse‐phase high‐pressure liquid chromatography. F‐CIF is a polypeptide which does not compete for binding to epidermal growth factor (EGF) receptors, but stimulates normal fibroblasts to form small colonies in semisolid medium and very large colonies in the presence of added EGF (2 ng/ml). In contrast to unfractionated mouse serum, purified F‐CIF did not induce C3H/10T1/2 cells to grow in soft agar, suggesting that serum contains additional cell type‐specific agar growth‐stimulating activities.
Estrogen receptor‐mediated cytotoxicity using iodine‐125
Authors: Bloomer W. D. , McLaughlin W. H. , Milius R. A. , Weichselbaum R. R. , Adelstein S. J. 
Published: December 2004

AbstractAuger effects from 125I decay are singularly damaging if localized in DNA as the thymidine analogue 125I‐iododeoxyuridine (125IUdR). Recent experience with steroid sex hormones extends these observations by demonstrating cytotoxicity in sites other than the DNA backbone. We have compared the cytotoxicity in human MCF‐7 breast cancer cells of 125IUdR, 125I‐iodotamoxifen, a nonsteroidal antiestrogen that is translocated from the cytoplasm to the nucleus of receptor containing cells, and 125I‐iodoantipyrine, a biological indicator of the body water space. Cytotoxicity is critically dependent upon subcellular localization.