Search PubMed⌕ Search

Biomedical subjects

E M Scolnick

Publications and source records attributed to E M Scolnick.

At least 163 records · Page 9Linked to original sources
PubMed1974

Dexamethasone stimulation of murine mammary tumor virus expression: a tissue culture source of virus.

In mouse cell lines derived from mammary adenocarcinomnas, the synthetic steroid dexamnethasone stimulates production of murine mammary tumor virus. Viral RNA and antigens are increased as much as 20-fold, and culture fluid supernatants from steroid-treated cells contain type B particles with reverse transcriptase. These cells provide a possible tissue culture source of this virus and a model system for studying the mechanism of action of corticosteroids and the regulation of transcription of integrated viral DNA.

Animals↗
PubMed1974

Immunochemical characterization of two major polypeptides from murine mammary tumor virus.

A major murine mammary tumor viral (MMTV) antigen, sl, originally described by Nowinski et al. (1967, 1968, 1971), has been purified from RIII mouse milk MMTV by sequential ion-exchange and gel chromatography. The purified protein with sl antigenic reactivity contains carbohydrate, and has an apparent minimal molecular weight of 52,000. It can be designated as gp52 (sl). Another major MMTV viral protein with a molecular weight of 27,000 has also been isolated, and antisera have been prepared against it. Both MMTV gp52 (sl) and p27 viral polypeptides have been iodinated with (125)I and used in immunoprecipitation and competition assays. The two MMTV proteins differ absolutely from each other and from major mouse type C viral polypeptides in molecular weight, immunological reactivity, and amino acid composition. Purified gp52 (sl) in radioimmunoprecipitation inhibition assays reacted in two distinct patterns. One pattern showed partial displacement of antibody which could be converted to the second, a complete displacement, by heating the antigen, presumably by exposing additional reactive determinants. Biologically, the patterns of major MMTV polypeptide expression in milk correlated with spontaneous mammary tumor incidence in different strains of mice, indicating that the sl antigen is group specific for MMTV or that several mouse strains contain the same virus type.

Amino Acids↗
PubMed1974

Harvey sarcoma virus: a second murine type C sarcoma virus with rat genetic information.

The nucleic acid sequences found in the Harvey strain of murine sarcoma virus have been analyzed by RNA.[(3)H]DNA and [(3)H]RNA.DNA hybridization techniques. The Harvey strain of murine sarcoma virus has been found to possess at least two sets of nucleic acid sequences. One set of sequences is contained in the Moloney strain of mouse type-C virus, and the other set is contained in DNA transcripts synthesized in endogenous reactions containing rat type-C virus(es). The nucleic acid sequences that are detected in the Harvey sarcoma virus with the DNA probes synthesized from the rat type-C virus(es) are related to the rat sequences detected in the Kirsten strain of murine sarcoma virus. The results support the model that both Kirsten and Harvey sarcoma viruses arose through a process of recombination or reassortment between mouse type-C viruses and sequences in rat cells and suggest that the information for transformation of fibroblasts may be contained in the rat type-C or cellular genome.

Animals↗
PubMed1974

Levels of rat cellular RNA homologous to either Kirsten sarcoma virus or rat type-C virus in cell lines derived from Osborne-Mendel rats.

DNA transcripts from V-NRK and RT21c rat type-C viruses were found to differ in their sequence homology to Kirsten and Harvey sarcoma viruses. V-NRK DNA transcripts consistently had homology to Kirsten and Harvey sarcoma virus, whereas RT21c DNA transcripts did not. To explain the differences, the nucleic acids and structural proteins of the two type-C viruses, released from each of two cell lines derived from Osborne-Mendel rats, were analyzed by molecular hybridization and competition radioimmunoassays. The p30 and p12 structural proteins of the two viruses were found to be highly related immunologically. In the V-NRK virus preparation, two sets of distinct RNA sequences were found in approximately equal amounts. One set is homologous to Ki-SV, and the other homologous to RT21c. In contrast, the RT21c virus preparation was found to contain a different ratio of these sequences. In this case the RT21c-like RNA sequences are present in 100-fold excess as compared to the additional Ki-SV specific sequences. Both NRK and RT21c cells contain in their DNA the full complement of Ki-SV homologous sequences, but NRK cells express much higher levels of these Ki-SV sequences in their RNA. These additional sequences, not homologous to RT21c, which are detected in uninfected NRK cellular RNA or V-NRK rat virus, could also be detected in the 60-70S RNA from a Moloney mouse type-C virus released from the NRK cells infected with the Moloney type-C virus. The results suggest that type-C viruses released from NRK cells incorporate species of RNA present in NRK cells which are homologous to Kirsten and Harvey sarcoma viruses. Either these sequences are of cellular origin, or rat cells contain two endogenous viruses with completely distinct nucleic acid sequences.

Animals↗
PubMed1973

Radioimmunoassay of mammalian type C viral proteins. 3. Detection of viral antigen in normal murine cells and tissues.

A radioimmunoassay specific for a murine leukemia virus structural protein, the gs antigen, detects an antigenic reactivity in normal murine cells in culture and natural tissues. The assay was shown to measure an antigen that is highly related to the virion protein as shown by absorption tests, immunoadsorbent chromatography, and by analysis of linearized dose-response curves. These findings combined with the finding of viral-specific RNA indicate that portions of the viral genome are being expressed with a much greater frequency than previously appreciated.

Animals↗
PubMed1973

Characterization and separation of viral DNA polymerase in mouse milk.

Two DNA polymerase with properties of viral RNA-directed DNA polymerase can be found in RIII mouse milk. One enzyme is the polymerase of type-C viruses; this enzyme prefers manganese to magnesium with poly(rA).oligo(dT) as synthetic template, is inhibited by specific sera, and has an apparent molecular weight of 70,000. Milk from BALB/c and NIH Swiss mice contain a vast predominance of this type-C enzyme. The other DNA polymerase from RIII mouse milk prefers magnesium to manganese, is not inhibited by type-C antipolymerase serum, and appears larger on gel chromatography than the type-C viral polymerase. Its presence in milk from RIII mice and absence from milk of mice with low content of mammary tumor virus correlates to the relative degree of type-B virus expression in these mice. The DNA polymerase of Mason-Pfizer monkey virus, isolated from a rhesus monkey breast tumor, also has a marked preference for magnesium with poly(rA).oligo(dT), is not immunologically related to primate type-C viruses, and appears larger than the gibbon type-C enzyme on gel chromatography.

Adenine Nucleotides↗
PubMed1973

Studies on the nucleic acid sequences of Kirsten sarcoma virus: a model for formation of a mammalian RNA-containing sarcoma virus.

The genetic information contained in the Kirsten and Moloney strains of mammalian RNA-containing sarcoma viruses has been analyzed by RNA . (3)H-DNA hybridization. Kirsten sarcoma virus has been found to possess two distinct sets of nucleic acid sequences. One set of sequences is contained in murine type C helper virus, and the other set is contained in rat type C helper virus. Moloney sarcoma virus contains sequences of murine type C helper virus but not of rat type C helper virus. The results indicate that Kirsten sarcoma virus arose through a process of recombination between Kirsten murine leukemia virus and nucleic acid sequences found in rat cells. A model is suggested for the formation of transforming type C viruses involving the transduction of oncogenic information.

Animals↗
PubMed1973

Partial transcription of murine type C viral genomes in BALB c cell lines.

The mouse cell line, BALB/c 3T3, and its derivatives transformed either spontaneously or by treatment with a variety of external agents, were analyzed for cytoplasmic RNA complementary to DNA products prepared from the Kirsten strain of murine sarcoma-leukemia virus, and from an endogenous type C virus of BALB/c 3T3. Although none of these cell lines spontaneously releases complete type C virions, they all contain RNA which is partially homologous to a portion of the 35S RNA isolated from these viruses. The parental cell line, BALB/c 3T3, contains a low level of viral-related RNA, and there is an increased amount of this RNA in some of the transformed cells. The RNA detected represents only a fraction of the viral RNA found in virus-producing cells. The formation of RNA:DNA hybrids was detected by equilibrium centrifugation in Cs(2)SO(4) density gradients and by analysis with a single-strand-specific nuclease from Aspergillus oryzae. Viral DNA products prepared either from an endogenous reaction with whole virus in the presence of actinomycin D or from purified 70S viral RNA as template using avian myeloblastosis virus DNA polymerase yield comparable data. In addition, all of the BALB/c lines examined produce detectable levels of murine type C virus group-specific antigen.

Animals↗