INHIBITION OF REGENERATION OF PLANARIA BY MIDLETHAL EXPOSURES TO X RAYS,
Abstract
The paper reports the results of studies on the radiosensitivity of the planarian worm, Dugesis dorotocephala, and on the effect of X-rays on the capacity to regenerate after decapitation. The LD50/60 of intact worms is 1303 R (95% confidence interval 1198-1408 R). The mean survival time is 33.7 days. Worms decapitated immediately after exposures ranging from 200 to 1600 R regenerate normally even if they die later. Worms decapitated 9 days after exposures to 200 or 400 R, regenerate normally, whereas, after exposures to 800 or 1600 R, they do not. In an experiment in which worms were exposed to 800 R and then decapitated at various times from 1 hour to 55 days after irradiation, it was shown that worms lose and then regain the capacity to regenerate: the curve representing the capacity for normal regeneration as a function of time after irradiation (percentage of worms regenerating normally after being decapitated at various times) falls from 100% at 1 hour to 50% at 3 days to 0% at 7 days. Recovery of capacity starts at 10-14 days and is 50% complete by about day 20 and essentially complete by about day 30. The phenomenon described may prove useful in studies of the relationship between cell population kinetics and recovery from sublethal radiation damage. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 08, 1968
- Accession Number
- AD0668330
Entities
People
- D. Stuart Nachtwey
- Kathleen Kendall
Organizations
- Naval Radiological Defense Laboratory