DIFFERENTIAL LETHAL EFFECTS OF MIXED REACTOR RADIATIONS ON LOGARITHMIC-PHASE AND SYNCHRONIZED TETRAHYMENA PYRIFORMIS,
Abstract
Logarithmic-phase and heat-shock synchronized Tetrahymena pyriformis cells were subjected to mixed neutron-gamma radiations (2.7:1) from a Mark F Triga reactor. A median lethal dose (LD50/48 hours) for logarithmic-phase cells was 70 krads (95% confidence interval: 68 to 73). The LD50/48 hours for heat-treated cells irradiated at 6 minutes after the end of the synchronizing treatment was 174 krads (95% confidence interval: 170 - 178). The approximately 2.5-fold resistance of heat-treated cells relative to logarithmic-phase cells might be related to the fact that heat-treated cells at the end of the synchronizing treatment contain 2 - 4 times the amounts of DNA found in logarithmic-phase cells. However, since heat-treated cells also are 2 - 4 times larger and contain 2 - 4 times the amount of RNA, other factors cannot be excluded. The possibility that the resistance of synchronized cells results from being irradiated at a particularly insensitive stage in the cell cycle is discussed; it is concluded that this explanation is unlikely. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 29, 1968
- Accession Number
- AD0671943
Entities
People
- D. S. Nachtwey
Organizations
- Naval Radiological Defense Laboratory