Search results for "nucleus"
showing 10 items of 1803 documents
On the relevance of genotoxicity for fish populations II: genotoxic effects in zebrafish (Danio rerio) exposed to 4-nitroquinoline-1-oxide in a compl…
2003
In order to characterize the impact of genotoxic potentials on populations of aquatic organisms in surface waters, zebrafish (Danio rerio) were exposed to the model genotoxicant 4-nitroquinoline-1-oxide (NQO) in a complete life-cycle test. Fish exposed to mean NQO concentrations of 0, 0.1, 0.3, 1.1, and 2.9 microg/l were examined by several genotoxicity assays with different endpoints. Assays included the unscheduled DNA synthesis (UDS) test, the comet assay, the alkaline filter elution, and the micronucleus test. The genotoxicity assays revealed an increasing genotoxicity, ranging from induction of DNA repair (even at the lowest concentration tested) to primary and secondary DNA alteration…
Single molecule localization microscopy of the distribution of chromatin using Hoechst and DAPI fluorescent probes.
2014
Several approaches have been described to fluorescently label and image DNA and chromatin in situ on the single-molecule level. These superresolution microscopy techniques are based on detecting optically isolated, fluorescently tagged anti-histone antibodies, fluorescently labeled DNA precursor analogs, or fluorescent dyes bound to DNA. Presently they suffer from various drawbacks such as low labeling efficiency or interference with DNA structure. In this report, we demonstrate that DNA minor groove binding dyes, such as Hoechst 33258, Hoechst 33342, and DAPI, can be effectively employed in single molecule localization microscopy (SMLM) with high optical and structural resolution. Upon ill…
Alteration of nuclear (2'-5')oligoriboadenylate synthetase and nuclease activities preceding replication of human immunodeficiency virus in H9 cells.
1988
After infection of the respective target cells with the human immunodeficiency virus (HIV-1) viral progeny is produced only after a short temporary delay of some days, depending on cell type. After this period of time a sudden onset of HIV-1 protein synthesis with a dramatic increase in virus release occurs. (2'-5')Oligoriboadenylates [(2'-5')A], capable to activate a latent ribonuclease (RNase L) degrading both mRNA and rRNA, are known mediators involved in the early response of cells to virus infection. Here we show that the (2'-5')A-synthesizing (2'-5')A synthetase, which is inducible by interferon and activated by double-stranded RNA, as well as a (2'-5')A nuclease (2',3'-exoribonucleas…
DAZAP2 acts as specifier of the p53 response to DNA damage.
2021
Abstract The DNA damage-responsive tumor suppressors p53 and HIPK2 are well established regulators of cell fate decision-making and regulate the cellular sensitivity to DNA-damaging drugs. Here, we identify Deleted in Azoospermia-associated protein 2 (DAZAP2), a small adaptor protein, as a novel regulator of HIPK2 and specifier of the DNA damage-induced p53 response. Knock-down or genetic deletion of DAZAP2 strongly potentiates cancer cell chemosensitivity both in cells and in vivo using a mouse tumour xenograft model. In unstressed cells, DAZAP2 stimulates HIPK2 polyubiquitination and degradation through interplay with the ubiquitin ligase SIAH1. Upon DNA damage, HIPK2 site-specifically ph…
In Vitro Assessment of the Genotoxic Hazard of Novel Hydroxamic Acid- and Benzamide-Type Histone Deacetylase Inhibitors (HDACi)
2020
Histone deacetylase inhibitors (HDACi) are already approved for the therapy of leukemias. Since they are also emerging candidate compounds for the treatment of non-malignant diseases, HDACi with a wide therapeutic window and low hazard potential are desirable. Here, we investigated a panel of 12 novel hydroxamic acid- and benzamide-type HDACi employing non-malignant V79 hamster cells as toxicology guideline-conform in vitro model. HDACi causing a &ge
Genomic instability induced by α-pinene in Chinese hamster cell line.
2012
Here, we report the effects of exposure of mammalian cells to α-pinene, a bicyclic monoterpene used in insecticides, solvents and perfumes. Morphological analysis, performed in V79-Cl3 cells exposed for 1 h to increasing concentrations (25 up to 50 μM) of α-pinene, indicated a statistically significant increase in micronucleated and multinucleated cell frequencies; apoptotic cells were seen at 40 and 50 μM. This monoterpene caused genomic instability by interfering with mitotic process; in fact, 50% of cells (versus 19% of control cells) showed irregular mitosis with multipolar or incorrectly localised spindles. Cytogenetic analysis demonstrated high-frequency hypodiploid metaphases as well…
Nuclear expression of apurinic/apyrimidinic endonuclease increases with progression of ovarian carcinomas.
2003
Apurinic/apyrimidinic endonuclease (APE alias Ref-1) is a key enzyme in the base excision repair pathway. Besides its function in DNA repair, APE serves to maintain several transcription factors in an active reduced state such as c-Fos, c-Jun, NF-kappaB, p53 and HIF-1alpha, all of which have been shown to play a role in tumorigenesis. Because of the importance of APE in maintaining genomic stability and gene regulation, we examined whether APE expression is associated with survival and histopathological parameters of patients with ovarian cancer.Tissue sections of primary epithelial ovarian carcinomas from 141 patients were immunostained using a monoclonal antibody directed against APE.Nucl…
Characterization of Different Deoxyribonucleases in Human Lymphocytes
1975
Abstract Deoxyribonucleases, Disc Electrophoresis, Lymphocytes Four groups of deoxyribonuclease activities from human lymphocytes have been characterized by deoxyribonuclease assay in DNA-containing polyacrylamide gels following their separation by disc-electrophoresis. All activities hydrolyse DNA endonucleolytically. One neutral deoxyribo nuclease found in the cytoplasmic fraction prefers native or UV-irradiated DNA over denatured DNA as substrate and is a 5′-monoester former. Two groups of acid deoxyribonuclease activities are detectable in the nuclear fraction. Both are 3′-monoester formers. One is as well active with denatured DNA as with native DNA, the other one shows the same activ…
Termite Gut Symbiotic Archaezoa Are Becoming Living Metabolic Fossils
2003
ABSTRACT Over the course of several million years, the eukaryotic gut symbionts of lower termites have become adapted to a cellulolytic environment. Up to now it has been believed that they produce nutriments using their own cellulolytic enzymes for the benefit of their termite host. However, we have now isolated two endoglucanases with similar apparent molecular masses of approximately 36 kDa from the not yet culturable symbiotic Archaezoa living in the hindgut of the most primitive Australian termite, Mastotermes darwiniensis . The N-terminal sequences of these cellulases exhibited significant homology to cellulases of termite origin, which belong to glycosyl hydrolase family 9. The corre…
The nuclear autoantigen La/SS-B: Mapping and sequencing of the gene and the three retropseudogenes
1997
One target of autoantibodies in sera of patients with systemic lupus erythematosus or primary Sjogren's syndrome is the nuclear autoantigen La/SS-B. Lambda clones and cosmids were isolated, which contained the sequences of the La gene and the three La pseudogenes. They were used for preparation of a physical map. Finally, the La gene and pseudogenes were sequenced. The pseudogenes were characterized as retropseudogenes. Their evolutionary ages were estimated to be approx. 4, 4.5 and 5 million years. Inserts of 4, 16 and 24 nucleotides, which were mostly A-residues, were found in exon 7 of the respective pseudogene. The oldest pseudogene contained the longest insert, the youngest pseudogene …