The space environment contains two major biologically significant influences; space radiation and microgravity. The tumor suppressor gene product p53 is generally thought to contribute to the genetic stability of cells with DNA damage through the activity of p53 initiated signal transduction pathways. We propose to investigate the expression of p53-regulated genes in cultured mammalian cells after exposure to a space environment. We expect that the data from this proposal will be useful for designing physiological protection against the serious effects of space radiation during long-term stays in space.

抄録全体を表示

This is a review paper to introduce how our developing methodology for loss of heterozygosity (LOH) analysis is predictable to detect the biological effects of space radiation. An experiment was successfully performed at 'Kibo' facility of International Space Station (ISS) from November 2008 to March 2009. If the field is restricted to life science, this is the first experiment at 'Kibo'. In this first experiment, we designed to elucidate the following influences of space-radiation and microgravity in human lymphoblastoid cell, TK6: i) a mutagenic effect of space radiation, ii) an effect of microgravity on mutation induction, and iii) a radioadaptive response after recovering the sample to the earth. Since the cells were successfully brought back to the earth at the beginning of April, we just started to analyze mutagenic effects of the frozen cells which were exposed to space radiation during about 4 months and half preservation at 'Kibo', determine influences of microgravity effects on induction of mutations by analyzing the cells incubated during 8 days under 1G or μG at 'Kibo', and evaluate a potential ability of the above frozen-cells to induce a radioadaptive response by measuring the repair efficiencies of DNA double-strand breaks introduced after recovering the sample to the earth.

抄録全体を表示

Organisms are exposed to various low-dose radiation in space. Ionizing radiation causes diverse damage, carcinogenesis, and cell death; however, low-dose radiation is reported to induce adaptive responses, different from high dose. The radioadaptive response caused by low-dose radiation is an important factor in the adaptation to life in space; therefore, we tried to identify a biomarker protein as an indicator of radioadaptive response, and to develop an index of adaptability to a stay in space. In the present review, the radioadaptive response in cultured astrocytes and the effects of aging will be described, in addition to the proteomics approach for the variation of protein expression and phosphorylation involved in the radioadaptive response.

抄録全体を表示

Development of a short and thick body by reorientation of cortical microtubules is required for the resistance of plants to the gravitational force. Katanin has microtubule-severing activity and is involved in the reorientation of cortical microtubules. Here, we investigated the effects of hypergravity produced by centrifugation on the expression of VaKTN1 gene encoding katanin. Hypergravity at 300 G increased the transcript level within 15 min, and the level reached maximum at 45 min. Then, the level was decreased and returned to the control range at 2 h. Also, the expression of VaKTN1 gene was increased transiently by removal of hypergravity stimulus. Changes in the microtubule-severing activity as a result of the modification of VaKTN1 expression in response to changes in gravitational conditions may be involved in the regulation of the orientation of cortical microtubules, leading to changes in the shape of plant body. Lanthanum and gadolinium ions, potential blockers of mechanosensitive calcium ion-permeable channels (mechanoreceptors), nullified the up-regulation of VaKTN1 gene, suggesting that mechanoreceptors are responsible for regulation by gravity of VaKTN1 expression. (c)2009 Jpn. Soc. Biol. Sci. Space; Article ID: 092301004

抄録全体を表示