The First Life Science Experiments in ISS: Reports of "Rad Gene"-Space Radiation Effects on Human Cultured Cells-

Abstract

To clarif y the biological ef fe cts of space environment, especially space radiations, a proposal of " Rad Gene" was performed as the first life science experiment with two human lymphoblastoid cell lines bearing wild-type p53 gene (wtp53) and mutated p53 gene (mp53) in an International Space Station (ISS) for 133 days. We scheduled four projects: (1) DNA damage induced by space radiations including the high linear energy transfer (LET) particles was detected as a track of γH2AX foci in the nuclei of these frozen cells. (2) To examine the biological effects of microgravity and space radiations on gene and protein expression of p53 -dependent regulated genes, these cells were grown under microgravity and 1 gravity in ISS, and on ground for 8 days and analyzed by DNA and protein arrays. (3) p53-Dependent regulated genes were analyzed in the cultured cells after spaceflight at frozen state exposed to space radiations. (4) To clarify the effects of space radiations on the radioadaptive response, the space flown cells at frozen state were cultured, and then exposed to challenging X-ray-irradiation. All of the radioadaptive responses of cell killing, apoptosis, chromosomal aberrations and mutations were found only in wtp53 cells, but not in the mp53 cells.

Life science experiments performed in space in the ISS/Kibo facility and future research plans

“…Many reports have already been published concerning radiation-induced HSPs [ 6 ]. Notably, there is an accumulation of Hsp70 in muscle, skin and spleen of space-exposed goldfish [ 1 ]. One of the stress-response activators of p300 stimulates the transcription of HSP genes through p53 activity.…”

“…These measurements were obtained by Dr Akiko Nagamatsu et al . in the JAXA group for life science experiments [ 1 ]. The plastic nuclear detector CR-39 was used to measure high linear-energy-transfer (LET) radiation, and thermo-luminescence dosimeters were used to measure low-LET radiation.…”

“…Physical dosimetry monitors were also attached to experimental biological samples and placed in several locations in the ISS/Kibo facility. This provided physical dosimetry information for space radiation on the ISS [ 1 ]. It was calculated that the dose rate during recent space flights was about 0.5 mSv per day.…”

Observer-Based Adaptive Fuzzy Finite-Time Control Design With Prescribed Performance for Switched Pure-Feedback Nonlinear Systems

“…The research results of pure-feedback switched systems are relatively fewer than the strict-feedback nonlinear systems [10]- [13]. In [14] and [15], for the pure-feedback nonlinear system, the mean value theorem is employed to process the system functions, and the completely non-affine form is transformed into the affine form. Furthermore, many researchers use backstep-ping techniques to design adaptive control approaches for pure-feedback nonlinear system [16]- [22].…”