| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1987: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1986: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Research Abstract |
Thymocytes are highly radiosensitive and show interphase death within a few hours after low doses of irradiation. recently,we obtained evidence to indicate that the radiation-induced interphse death of thymocytes is a king of programmed death named"apoptosis". In the present study,the mechanisms underlying the cell death were investigated.
Rat thymocytes irradiated in vitro with 1 KR X-rays underwent interphase death,judged by erythrosin B staining,accompanying discrete cell size reduction and DNA degradation. The cell death as well as these changes were completely blocked by inhibitors of RNA and protein synthesis such as actinomycin D and cycloheximide.These results suggest strongly that the cell death is not a passive event,but an active process requiring the programmed synthesis of specific RNA and proteins. After 10 KR irradiation, however, gradual swelling of cells, oen of the characteristic changes of necrosis,was observed and cell death could no more be prevented by cyckoheximide.It is possible,therefore,that some process of protein synthesis reauired to develop apotosis was damaged by the high doses irradiation.As a result cells die not by apoptosis,but by necrosis after massive doses irradiation.For detection of proteins which might perticipate in paoptosis,two demensional ge%i elcrophoresis of the proteins of the viable and dead cells separated by Percoll density gradient was conducted. In comparison with the proteins of viable cells we could detect specific appearance of 27 kDa protein and disapearance of 29 kDa protein in the dead cells.Investigations concerning these proteins are now in progress.
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