Abstract
The space environment is generally symbolized by the micro-gravity. The exposure to low-dose/low-dose-rate space radiation is also considered to be an important factor. These factors must be solved not only from the view point of astronauts health but also from the wide-range aspects of future space-utilization. It is important to establish the biological experimental systems to estimate the effects of radiation exposure separately from the microgravity effects. The system is also expected to approach the existence of synergistic effects of these two factors, in which there are conflicting results obtained by the different systems in the flight experiments. The simple long-stay of biological samples in the ISS could not promise us to provide more confidential results reflecting the space environments. In other words, it is required to construct the appropriate assay systems at different levels such as molecules, cells and experimental animals. Here we would like to introduce an ISS experiment plan, which is focusing on the mutagenic effects among the various types of genetic influences to perform the sensitive detection of radiation exposure effects as well as the microgravity effects. We have already succeeded to develop the loss of heterozygosity (LOH) analysis system using human lymphoblastoid TK6 cell. Recently, the frozen TK6 cells were exposed to 10 cGy of carbon-ion beam (135 MeV/u). Similar to the exposure as the suspension culture, the radiation-specific LOHs (interstitial deletions) were observed after the exposure.The preparations for ISS Exp are also reported.
