Worm Breeder's Gazette 7(2): 62
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.
The dauer larva (1) stage believed to be the period of the active DNA repair because (a) neither of the degree of the resistance to irradiation (during a 60 days non-aging period of the dauer larvae) (b) nor the lengths of the life span of irradiated dauer larvae decreased (2, 3). Genetic dissection and analysis of DNA repair mechanisms is possible by mutants of altered (usually deficient) repair activity. Such mutants of C.elegans isolated so far are hypersensitive to DNA damaging agents like UV (4). We have accomplished some comparative experiments aimed to reveal possible relations between the physiological state of the dauer larvae and their responses to UV irradiation. Our findings can be summarized as follows: 1. The egg inactivation curves of wild type (N2) and dauer constitutive (daf-c) mutants like daf-2(e1370) and daf-7 (e1372) (5) were different. The daf-c mutants seemed to be more resistant throughout their life. 2. The inactivation curves (based upon the fraction of the irradiated population capable to grow as a function of the applied UV doses) of L2s and dauers were different. The dauers seemed to be more resistant but this difference was not as striking as it had been expected. However, while those irradiated dauers which were able to grow became usually perfectly fertile adults, these irradiated L2s which were able to develop became sterile, semisterile, or sick animals on a large scale of variation. At higher doses (fatal to the whole population of L2s or L3s) a tiny subpopulation of dauers was still able to grow and developed usually to fertile adults. We concluded that the dauer stage protected fertility, but the dauer recovery as a process was UV sensitive. It might be related to some dauer-specific structure because, when irradiated (daf-c) L1 or L2 larvae managed to grow to dauers, they were also capable to recover. 3. Dauer formation is also a UV sensitive process. When animals younger than dauers were irradiated with different doses, a part of the population failed to grow; another part became normal dauers ( capable also to recover) and a further subpopulation (the size of them was proportionate to the UV dose) looked healthy but failed to form dauers. This fraction of daf-2s could not develop beyond late L2, but a part of their daf-7 counterparts avoided the dauer stage and became usually sterile adults. The response of N2 was similar to that of daf- 7 in preliminary experiments in which irradiated embryos were allowed to develop in the presence of DRIF (WBG 6, (1:) 25). All but the dauer recovery experiments were carried out on 25.4 C.