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Biomedical subjects

M Green

Publications and source records attributed to M Green.

At least 865 records · Page 48Linked to original sources
PubMed1975

Inhibition of purified DNA polymerase of RNA tumor viruses by fluoranthene derivatives and analogues of tilorone hydrochloride.

At concentrations of 7 times 10(-6) to 7 times 10(-5) M, derivatives consisting of the polycylic ring structures fluoranthene, fluorenone, fluorene, anthraquinone, xanthenone, and dibenzofuran with appropriate amine side chains inhibited by over 90% the purified RNA-directed DNA polymerase of avian myeloblastosis virus acting on poly(deoxyadenylate-deoxythymidylate) [poly(dA-dT)]. Of these, only the fluoranthene derivatives were strong inhibitors of the viral DNA polymerase directed by polyadenylate-oligodeoxythymidylate [poly(A)-(dT)12-18]. Low levels of fluoranthene derivatives (1 times 10(-5) M) also strongly inhibited polymerase with polyinosinate-oligodeoxycytidylate [poly(I)-(dC)12-18], activated calf thymus DNA, and viral 70S RNA as templates, but not with polycytidylate-oligodeoxyguanylate as template. A comparison of the activity of 11 fluoranthene derivatives with different side chains showed that the structure of the amine side chain influenced both the extent of antipolymerase activity with a given template and the relative inhibition with different synthetic DNA and RNA templates. The naturally occurring polyamines, spermine, spermidine, and putrescine, did not inhibit the activity of the viral DNA polymerase. Studies on the mechanism of action indicated that the synthetic derivatives inhibited polymerase activity by binding to the template and not to the enzyme: 1) inhibition by fluoranthene derivatives was overcome by the addition of excess template including poly(dA-dT), poly(A)-(dT)12-18, poly(I)-(dC)12-18, viral 70S RNA, and activated calf thymus DNA; 2) the degree of inhibition by fluoranthene derivatives was unaffected by the addition of the creased viral DNA polymerase; 3) with the same template, Escherichia coli DNA-directed RNA polymerase and the viral RNA-directed DNA polymerase were inhibited to about the same extent; and 4) the derivatives formed a complex with DNA, poly(I), and poly(A) that was stable to exclusion chromatography on Sephadex G-100. Several derivatives also had biologic activity, since they blocked the ability of the murine sarcoma virus to transform cells.

Anthraquinones↗
PubMed1974

The homopolyadenylate and adjacent nucleotides at the 3'-terminus of 30-40s RNA subunits in the genome of murine sarcoma-leukemia virus.

Adenosine is the major 3'OH-terminal nucleoside of the 60-70S RNA genome of the murine sarcoma-leukemia virus, its 30-40S RNA subunits, and the poly(A) segments derived by RNase treatment of both RNA species, as determined by periodate oxidation-[(3)H]-borohydride reduction. The binding 30-40S RNA to oligo(dT)-cellulose suggests that most viral RNA subunits contain poly(A). The molecular weight of poly(A) derived from viral RNA by digestion with RNase and purified by affinity chromatography is 64,000-68,000, as determined by gel electrophoresis. From the size of poly(A) and the poly(A) content of viral RNA (1.6%), it is estimated that there is about one poly(A) segment for each viral 30-40S RNA subunit. The results of 3'-termini labeling with [(3)H]borohydride, in vivo labeling with [(3)H]adenosine, and base composition of [(32)P]poly(A) indicate that a homopoly(A) segment is located at the 3'-end of a 30-40S RNA subunit. The homogeneous poly(A) segments isolated from RNase T1 digests of 60-70S [(32)P]RNA consist of one cytidylate, one uridylate, and about 190 adenylate residues, while those isolated from RNase A digests consist exclusively of adenylate residues. These results indicate that -G(C,U)A(190)A(OH) is the 3'-terminal nucleotide sequence of the viral 30-40S RNA subunits.

Adenine Nucleotides↗
PubMed1974

Isolation of DNA Strand-specific early messenger RNA species in cells infected by human adenovirus 2.

Hybridization to the separated light (L) and heavy (H) strands of adenovirus 2 DNA in 50% formamide at 37 degrees was used to isolate undegraded virus-specific RNA molecules from the polyribosomes of cycloheximide-treated human KB cells early after infection with adenovirus 2. About 20% of polyribosomal RNA labeled with [(3)H]uridine from 4 to 7 hr after infection was virus-specific. Twice as much labeled RNA was homologous to the L strand as to the H strand. Polyacrylamide gel electrophoresis of RNA selected with unfractionated adenovirus DNA resolved a major component of virus-specific RNA in the 19-20 S region of the gel and smaller amounts of viral RNA in two heterogeneous fractions migrating at 15-18 S and 21-26 S. Selection with individual DNA strands showed that the 19-20 S main size class of early mRNA consists of two homogeneous RNA species with slightly different mobilities, the transcripts from the L and H strand having molecular weights of 7.4 x 10(5) and 7.7 x 10(5), respectively. The 15-18 S RNA hybridized with the L strand and the 21-26 S RNA with the H strand.

Adenoviridae↗
PubMed1974

Detection and localization of virus-specific DNA by in situ hybridization of cells during infection and rapid transformation by the murine sarcoma-leukemia virus.

Cytological preparations of interphase nuclei and chromosomes from mouse 3T6 cells prepared at various times after infection with the murine sarcomaleukemia virus complex were hybridized with the [(3)H]DNA product of the viral RNA-directed DNA polymerase. While uninfected nuclei had an average of 4 autoradiographic grains, infected nuclei had 30 grains at 5 hr after infection and 63-65 grains at 11 and 25 hr. Virus-specific grains were localized in the chromocenters of interphase nuclei and were found also in the centromeric heterochromatin region of metaphase chromosomes. These findings provide evidence that the viral RNA-directed DNA polymerase functions to synthesize virus-specific DNA early after infection and that newly synthesized viral DNA rapidly becomes associated with or integrated into specific intranuclear sites.

Animals↗
PubMed1974

Activation of the murine sarcoma virus genome after infection with the murine leukemia virus as determined by cell agglutination.

Non-virus-producing NIH/3T3 cells transformed by the murine sarcoma virus are agglutinated by conconavalin A to the same low level as normal NIH/3T3 cells. Infection with the murine leukemia virus greatly increases the agglutination of transformed cells but not that of normal cells. These data suggest that the morphological expression of cell transformation and the surface alterations associated with increased cell agglutination are controlled by the expressions of different sarcoma virus genes.

Agglutination↗
PubMed1974

Adenovirus DNA replication. I. Requirement for protein synthesis and isolation of nuclear membrane fractions containing newly synthesized viral DNA and proteins.

Nuclear membrane fractions were prepared by two procedures from KB cells pulse labeled with [(3)H]thymidine for 5 min late after infection with adenovirus 2: (i) the M-band technique, which yields a sharp peak containing most of the newly synthesized viral DNA, and (ii) the discontinuous sucrose gradient method, which yields three membrane fractions, one which bands at the interface between sucrose layers at density 1.18 and 1.20 g/ml and contains most of the newly synthesized viral DNA. Studies using cycloheximide to inhibit protein synthesis showed that proteins whose synthesis begins early after infection and occurs in the absence of viral DNA replication are required for viral DNA synthesis late after infection. To study the nature of these proteins, nuclear membrane fractions were isolated from cells labeled with [(3)H]leucine from 6 to 24 h postinfection in the presence of arabinosyl cytosine to block viral DNA replication, and were analyzed by electrophoresis in sodium dodecyl sulfate polyacrylamide gels. Two proteins of molecular weights 75,000 and 45,000 were the major labeled polypeptides in the nuclear membrane fractions prepared from infected cells both by the M-band and the discontinuous sucrose gradient methods. These two proteins were not found in nuclear membrane fractions from uninfected cells. It is suggested that the 75,000 and 45,000 proteins may be early viral gene products that may play a role in the viral DNA replication.

Adenoviridae↗
PubMed1974

Intracellular viral RNA species in mouse cells nonproductively transformed by the murine sarcoma virus.

The size and quantity of virus-specific RNA in five non-virus-producing mouse cells transformed by the Moloney isolate of murine sarcoma virus (MSV) was determined. Hybridization of RNA from transformed cells with the [(3)H]DNA product of the RNA-directed DNA polymerase of the murine sarcoma-leukemia virus was used to detect and quantitate virus-specific RNA. The amount of virus-specific RNA in non-virus-producing cells was less than one-sixth of that found in virus-producing cells. A striking correlation was found between the amount of intracellular virus-specific RNA and the degree of agglutination by conconavalin A previously reported for the four non-virus-producing NIH/3T3 cell lines (Salzberg and Green, 1974). A major RNA subunit sedimenting at 26 to 28S was detected in all five MSV-transformed non-virus-producing cells. This could represent the RNA genome of defective MSV.

Animals↗