Search results for "DNA synthesis"
showing 10 items of 46 documents
The DNA topoisomerase II catalytic inhibitor merbarone is genotoxic and induces endoreduplication
2012
Abstract In the last years a number of reports have shown that the so-called topoisomerase II (topo II) catalytic inhibitors are able to induce DNA and chromosome damage, an unexpected result taking into account that they do not stabilize topo II-DNA cleavable complexes, a feature of topo II poisons such as etoposide and amsacrine. Merbarone inhibits the catalytic activity of topo II by blocking DNA cleavage by the enzyme. While it was first reported that merbarone does not induce genotoxic effects in mammalian cells, this has been challenged by reports showing that the topo II inhibitor induces efficiently chromosome and DNA damage, and the question as to a possible behavior as a topo II p…
Intracellular signal transduction pathways in sponges.
1990
Abstract Sponges are the lowest multicellular eukaryotic organisms. Due to the relatively low specialization, and concomitantly the high differentiation and dedifferentiation potency of their cells, the sponge cell system has proven to be a useful model to study the mechanism of cell-cell adhesion on molecular levels. Results of detailed biochemical and cell biological studies with the main cell adhesion molecules, the aggregation factor (AF) and the aggregation receptor, led to the formation of the modulation theory of cell adhesion. The events of cell adhesion are contigent on a multiplicity of precisely coordinated intracellular signal transduction pathways. Using the marine sponge Geodi…
The effect of arabinofuranosyl-cytosine upon the synthesis of herpesvirus hominis Electron microscopic observations in relation to viral DNA-synthesis
1972
The paper describes experiments about the degree of dependency of capsid, envelope and antigen synthesis byherpesvirus hominis upon viral DNA synthesis. The DNA synthesis has been blocked by different doses of Ara-C and the remnant DNA-synthesis has been measured by [3H]-thymidine incorporation after CsCl-density gradient centrifugation. Electron microscopic studies were done in parallel after incubation of infected cells with different doses of Ara-C. Finally, antigens were prepared after infection without and with added Ara-C. Increasing amounts of Ara-C inhibited the synthesis of viral DNA and infective particles. 1.5 μg Ara-C reduced the remaining incorporation into DNA to about less th…
Synthesis and characterization of diorganotin(IV) complexes ofN-(2-pyridylmethylene)arylamines and mutagenicity testingin vivo of Et2SnCl2�[L4=N-(2-p…
1998
Diorganotin(IV) dichloride complexes of the type R 2 SnCl 2 .L (R = methyl, ethyl, vinyl, t-butyl, n-butyl or phenyl; L=N-(2-pyridylmethylene)arylamine) have been synthesized and characterized on the basis of IR, NMR and 119 Sn Mossbauer studies. Investigation of the complexes indicated that N-(2-pyridylmethylene)arylamines form distorted trans-octahedral complexes with R 2 SnCl 2 similar to the well-known R 2 SnCl 2 .L. Cytogenetic toxicology testing has been performed for Et 2 SnCl 2 .L 4 [L 4 = N-(2-pyridylmethylene)-4-toluidine] in mouse bone-marrow cells in vivo since such testing is a regulatory requirement before new drugs are released. This tin compound induced delay in cell-cycle k…
Changes in the cell wall glycoprotein composition of Candida albicans associated to the inhibition of germ tube formation by EDTA.
1994
Hyphal development in Candida albicans was blocked by EDTA. This effect was not due to a general growth inhibition since the chelator did not affect protein and DNA synthesis. Recovery of mycelial growth was observed when EDTA-grown cells were incubated at 37 degrees C in EDTA-free medium. High-molecular-weight mannoproteins (HMWM) that are mycelium-specific wall components, and particularly a 260-kDa species (HMWM-260), were absent in the wall of cells grown under germination conditions in the presence of EDTA. Synthesis of the HMWM-260 species was not inhibited but its incorporation (secretion) into the wall structure seemed to be blocked in EDTA-treated cells.
Specific phosphorylation of proteins in pore complex-laminae from the sponge Geodia cydonium by the homologous aggregation factor and phorbol ester. …
1987
We have recently shown that the aggregation factor (AF) from the sponge Geodia cydonium stimulates DNA synthesis in quiescent, dissociated cells from the same organism; this event was correlated with the release of the two second messengers: inositol trisphosphate and diacylglycerol. Here we describe that after binding of the AF to the plasma membrane-bound aggregation receptor, a rapid and drastic increase in the incorporation of 32Pi into a series of proteins in the pore complex-lamina fraction occurs. Addition of the tumor promoter, 12-O-tetradecanoylphorbol-13-acetate, to quiescent cells resulted in a similar stimulation of phosphorylation of nuclear proteins. Among them we have selecte…
Yeast dsRNA viruses: replication and killer phenotypes
1991
The cytoplasmic L-A dsRNA virus of Saccharomyces cerevisiae consists of a 4.5 kb dsRNA and the two gene products it encodes; the capsid (cap) and at least one copy of the capsid-polymerase (cap-pol) fusion protein. Virion cap-pol catalyses transcription of the plus (sense)-strand; this is extruded from the virus and serves as messenger for synthesis of cap and cap-pol. Nascent cap-pol binds to a specific domain in the plus strand to initiate encapsidation and then catalyses minus-strand synthesis to complete the replication cycle. Products of at least three host genes are required for replication, and virus copy number is kept at tolerable levels by the SKI antivirus system. S. cerevisiae k…
Detection of mammalian carcinogens with an immunological DNA synthesis-inhibition test.
1992
There is a close relationship between genotoxicity, mutagenicity and carcinogenicity. But the controversy of which short-term test system best recognizes human carcinogens is still going on. Currently, the Salmonella gene mutation assay ('Ames test') is the most widely used test for the screening of mutagens. However, many in vitro tests hold unsatisfactory validity data, presumably because of the inability of present short-term tests to detect non-genotoxic carcinogens, which are increasingly being brought into focus in the discussions of genesis of cancer. One principle often neglected in this context is the property of genotoxic agents to inhibit replicative DNA synthesis in (proliferati…
Immobilized glycolipids from human diploid fibroblasts inhibit DNA synthesis of cultured human fibroblasts*1
1987
Several previous studies have shown that glycolipids isolated from plasma membranes of cultured cells and added to cells in culture inhibit the growth rate in a concentration-dependent fashion. In order to investigate the possible involvement of glycolipids in the growth regulation of normal cells by cell-cell contacts, we tested the effect of immobilized glycolipids, isolated from human fibroblasts, on the DNA synthesis of freshly seeded fibroblasts. Gangliosides inhibited DNA synthesis to a great extent, whereas neutral glycolipids had only a minor effect. The degree of inhibition of DNA synthesis by immobilized gangliosides depended both on the cell density of the cultures from which the…
ID: 37
2015
During the early phase of human cytomegalovirus (HCMV) infection, the Interferon- γ -Inducible factor 16 (IFI16) behaves as a pattern recognition receptor (PRR) sensing viral DNA and triggering antiviral cytokine release. Later on, it restricts virus replication by down-regulating expression of viral genes committed to DNA synthesis including UL54 and UL44. These activities are modulated by viral proteins including pUL83, a tegument protein involved in viral evasion. Here, we demonstrate that pUL83 interacts with IFI16 relieving its inhibitory activity on UL54 gene transcription. We also establish that, starting from 48 h post-infection, IFI16 is stabilized and protected from degradation by…