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.

Effect of UV on Dauer Larvae, Dauer Recovery and Dauer Formation

A. Fodor, D. Riddle

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.