Worm Breeder's Gazette 13(5): 83 (February 1, 1995)
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.
Institute for Behavioral Genetics, University of Colorado. Campus Box 417, Boulder, C0 80309-0447, USA. e mail: murakams@ibg.colorado.edu
Longer life may come from a single mechanism in C.elegans. It has been proposed that longer life span can be achieved either by reduction of sperm formation (1), or by turning on some aspects of dauer formation (2). As a first step to understand the basis of longer life, we have searched for phenotypes shared among all the long-life mutants: age-l, daf-2 and spe-26. We excluded rad-8, because its life extension is due to delayed differentiation. An environmental stress, UV light, has been suggested as a factor that accelerates aging. We have focused on resistance to UV irradiation as a candidate phenotype. All the longer-life mutants showed more resistance to UV irradiation than wild type, N2. First, we tested whether age-l mutants were more resistant to UV at various energies from 5 to 60 J / m2. Immediate death of the hermaphrodites was observed at energies of more than 60 J / m2 so we have not examined higher doses than this. At energies from 5 to 40 J / m2, age-l mutant showed significantlygreater survival after the irradiation than wild type in 12 independent experiments. It is unlikely that this results from self-imposed dietary restriction (eating less or more extends life), because we could not find any difference in the percentage of worms pumping or in the pumping rate after UV. age-l survival after UV irradiation is also significantly different from wild type at 20 J / m (P < 0.0001; wild type: 3.2 -4.4 days; age-l: 4.6 - 5.9 days). However, the percentage of immediate death after the UV irradiation was similar between age-l and wild type, which is consistent with a previous study (3). This suggests that initial UV damage was similar between age-l and wild type. The recovery from the damage can be more efficient in age-l than in wild type. Similar results were obtained using daf-2 (el370), spe-26 (hc138) and spe-26 (it118) at 20 J / m2. In addition, there appeared a correlation between mean life span and the level of UV resistance (Fig. I; mean life span data used in the figure is from Ref.l, 2 and our results). Increased UV resistance was the first common phenotype seen in all of the longer-life mutants. Recently, similar results were obtained by checking increased thermotolerance (see Lithgow et al., in this issue). We would like to propose that a single mechanism which confers stress resistance also causes a longer life span in C elegans. 1 Van Voorhies. 1992. Nature. 360: 456458. 2 Kenyon et al., 1993. Nature. 366: 461464. 3 Hartman et al., 1988. Mutation Research 208: 77-82.