Worm Breeder's Gazette 8(2): 12
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
Wild-type (N2) and four radiation-sensitive (rad) mutant dauer larvae were tested for their abilities to develop into adults after UV irradiation. The rad-3 mutant was over 30 times as sensitive as N2; rad-1, were not hypersensitive. Irradiation also resulted in a significant delay in development. For example, over 95% of the unirradiated N2 dauer larvae completed development within three days of food presentation; however, fluences of 78 Jm-2 and 156 Jm-2 resulted in average delays of approximately 40 and 50 hours, respectively. In fact, higher fluences resulted in developmental periods as long as 7.5 days. Brood sizes decreased in a fluence-dependent fashion; however, most N2 survivors which were delayed in development for up to four days still produced greater than 10 offspring per animal. The fact that dauer larvae do not resume development until placed in the presence of food was exploited to test two aspects of their radiation response. First, the effect of dauer age on radiation sensitivity was examined by irradiating N2 dauer larvae at 0, 25 or 50 days after harvesting. Animals were collected and either irradiated immediately or incubated in PBS for 25 or 50 days before irradiation. There were no significant differences in radiation sensitivities. Second, the effect of post irradiation holding on survival was tested on N2 dauer larvae. Animals were irradiated with either 116 or 194 Jm- 2 and incubated in a non-nutritive medium (PBS) for various intervals before exposure to food. Liquid holding recovery (LHR) refers to the increased survival observed in many instances when irradiated organisms are held in a nonnutritive medium before plating. Genetic and biochemical evidence in both bacteria and yeast indicate that increased survival can be attributed to DNA repair that occurs during holding. No liquid holding recovery (LHR) occurred at either fluence; in fact, survival decreased after approximately five days of post- irradiation holding. In addition, no differences were observed in the amount of developmental delay imposed by radiation. These results imply that this developmental state is not a period of active DNA repair.