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Volume 25 (2011)
- Issue 2_4 Pages 37-
- Issue 1 Pages 3-
Volume 25, Issue 1
Displaying 1-3 of 3 articles from this issue
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Chizuru Tsuruoka2011 Volume 25 Issue 1 Pages 13-17
Published: 2011
Released on J-STAGE: June 26, 2012
JOURNAL FREE ACCESSThis paper introduces the effects of radiation quality with different ion species and various linear energy transfer on variable cell killing, remaining or initially measured breaks of G0/G1-prematurely condensed chromosome, mutation induction and deletion spectra in normal human fibroblasts. These results demonstrate that the LET-dependent structure is reflected in biological consequence of the repair process. Also, we indicate the possibility that the biological effects for different ion species are seen in not only a quantitative difference but also in a qualitative difference, in term of mutation induction. However, the importance of the biological effects caused by primary ions is still unclear in our irradiation systems, due to the use of polymethyl methacrylate absorbers of different thicknesses to change the energies of the ions. When considering the influence of galactic cosmic rays consists of high energy protons and heavy ions, it is important to further clarify the relationship between the different types of radiation and the effects.View full abstractDownload PDF (441K) -
Makoto Tabata, Yuko Kawaguchi, Shin-ichi Yokobori, Hideyuki Kawai, Jun ...2011 Volume 25 Issue 1 Pages 7-12
Published: 2011
Released on J-STAGE: June 26, 2012
JOURNAL FREE ACCESSHydrophobic silica aerogels with ultra-low densities have been designed and developed as cosmic dust capture media for the Tanpopo mission which is proposed to be carried out on the International Space Station. Glass particles as a simulated cosmic dust with 30 _m in diameter and 2.4 g/cm3 in density were successfully captured by the novel aerogel at a velocity of 6 km/s. Background levels of contaminated DNA in the ultra-low density aerogel were lower than the detection limit of a polymerase chain reaction assay. These results show that the manufactured aerogel has good performance as a cosmic dust collector and sufficient quality in respect of DNA contamination. The aerogel is feasible for the biological analyses of captured cosmic dust particles in the astrobiological studies.View full abstractDownload PDF (818K) -
Ping Zhang, Chang Jiang, Eric Ledet, Hiroki Yokota2011 Volume 25 Issue 1 Pages 3-6
Published: 2011
Released on J-STAGE: June 26, 2012
JOURNAL FREE ACCESSVarious cellular insults such as radiation, nutrient deprivation, hypoxia, and stress to the endoplasmic reticulum induce integrated stress responses (ISR), which activate phosphorylation of eukaryotic initiation factor 2 - subunitα (eIF2α). This activation of eIF2α phosphorylation decreases translational efficiency of a majority of proteins for preventing stress-driven apoptosis. In the present study, we addressed a pair of questions: Does mechanical loading or unloading activate phosphorylation of eIF2α? If yes, is GCN2 (general control repressed 2) responsible for its phosphorylation? To answer those questions, we employed C57BL/6 wildtype and GCN2 knockout mice and applied ankle loading and hindlimb suspension. The Western blotting results using loaded and unloaded tibia samples revealed that loading reduced the level of eIF2α phosphorylation regardless of the presence of GCN2 gene, while unloading elevated its phosphorylation. These results suggest that unloading is a unique form of integrated stress source, while appropriate loading can be its suppressor.View full abstractDownload PDF (939K)
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