Exposure to DNA damaging agents is known to induce an adaptive response in a variety of eukaryotic cells. Cells can become radioresistant to the damaging effects of ionizing radiation when pretreated with a lower, conditioning radiation dose [l]. An adaptive response has been described for a variety of eukaryotic cells exposed to numerous chemical and physical agents, in particular ioinizing ra...

Space represents an extremely harmful environment for life and survival of terrestrial organisms. In the last decades, a considerable deal of attention was paid to characterize the effects of spaceflight relevant radiation on various model organisms. The aim of this study was to test the survival capacity of the cryptoendolithic black fungus Cryomyces antarcticus CCFEE 515 to space relevant rad...

iran is one of several countries that has regions of high dose natural ionizing radiation. two wellknown villages in the suburb of ramsar town in the caspian sea strip, taleshmahaleh and chaparsar, have background radiation that is 13 times higher than normal. this radiation is the result of radium 226 and radon gas both of which are highly water soluble. while people living in these regions do...

To observe the adaptive response (AR) induced by ionizing radiation in human fibroblasts under monolayer and 3-dimensional (3-D) condition. Three kinds of fibroblasts were cultured under both monolayer and 3-D condition. Immunofluorescent staining was used to detect the γ-H2AX foci and the morphological texture. Trypan blue staining was used to detect the cell death. Western blot was used to de...

The function of protein phosphatase 1 nuclear-targeting subunit (PNUTS)--one of the most abundant nuclear-targeting subunits of protein phosphatase 1 (PP1c)--remains largely uncharacterized. We show that PNUTS depletion by small interfering RNA activates a G2 checkpoint in unperturbed cells and prolongs G2 checkpoint and Chk1 activation after ionizing-radiation-induced DNA damage. Overexpressio...

Adaptive responses can be induced in cells by very low doses of ionizing radiation resulting in an enhanced resistance to much larger exposures. The inhibitor of apoptosis protein, survivin, has been implicated in many adaptive responses to cellular stress. Computerized axial tomography used in image-guided radiotherapy to position and monitor tumor response uses very low radiation doses rangin...

ionizing radiation causes dna damage and chromosome abbreviations on normal cells. the radioprotective effect of celecoxib (clx) was investigated against genotoxicity induced by ionizing radiation in cultured human blood lymphocytes. peripheral blood samples were collected from human volunteers and were incubated at different concentrations at 1, 5, 10 and 50 μm of clx for two hours. at each do...

Proteasome activator PA200 enhances proteasome-mediated cleavage after acidic residues in vitro; however, its role within cells is not known. Here, we show that, in response to ionizing radiation, PA200 forms hybrid proteasomes with 19S caps and 20S core proteasomes that accumulate on chromatin, leading to an increase in proteolytic activity. Unlike many other proteins that respond to DNA damag...

Health risks of low doses of ionizing radiation (10 cGy or less) may not be accurately estimated in humans by epidemiological study or mathematical modelling because of several inherent confounding factors including environmental, dietary and biological variables that cannot be accounted for in any radio-epidemiological study. In addition, the expression of radiation-induced damage in humans no...

Activation of the S-phase checkpoint results in an inhibition of DNA synthesis in response to DNA damage. This is an active cellular response that may enhance cell survival and limit heritable genetic abnormalities. While much attention has been paid to elucidating signal transduction pathways regulating the ionizing radiation-induced S-phase checkpoint, less is known about whether UV radiation...