量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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Exposure of sublethal doses of ionizing radiation can induce protective mechanisms against a subsequent higher dose irradiation. We demonstrated the existence of this phenomenon, called adaptive response (AR), in mice during late organogenesis. Molecular mechanisms underlying AR in this model were investigated. Using DNA microarrays, AR-specific gene modulations were identified. Our results suggested the involvement of signal transduction and p53-related pathways in the induction of AR. In order to validate microarray results and to gain better insights into molecular mechanisms of AR in fetal mice, we analyzed the expression kinetics of several target genes by real-time quantitative fluorescence RT-PCR in different organs of irradiated embryos. Whole-body expression of Csf1 gene was significantly different after exposure to AR-inducing and non AR-inducing priming radiation. Comparative gene expression in adapted and non-adapted fetuses will be presented. In an in vitro model of cultured limb bud cells from mouse fetuses, we checked p53 protein expression and phosphorylation levels on Ser18 following priming and challenging irradiations. After exposure to challenging dose alone or to 0.5 Gy priming dose (not efficient for inducing AR) before challenging radiation, p53 protein expression and phosphorylation, initially at low levels, peaked 4 to 6h after exposure to challenge dose. When priming dose was performed in AR-inducing conditions, these values followed similar time course, but reached lower peak level. The involvement of p53 protein in AR in this model will be discussed.
会議概要（会議名, 開催地, 会期, 主催者等）
New Nuclear Research Symposium "Biological Responses to Low Dose Radiation"
Adaptive response in mice during late embyogenesis: gene modulations and role of p53
