Worm Breeder's Gazette 10(3): 86
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.
There is an attractive idea that active oxygen species act as a promoter of aging. In order to get knowledge on the relationship between active oxygen species and aging, we isolated mutants which are hypersensitive to paraquat (methylviologen). This is a herbicidal drug and is known to yield superoxide anion (O2-). First screening to isolate paraquat sensitive mutants N2 hermaphrodites were mutated with EMS. F2 progenies having eggs were treated with 30mM paraquat for 4 hr and inactive worms were separated onto small spotted NG agar plates. Paraquat sensitive F2 animals must die, but the eggs were expected to survive because paraquat does not enter into unhatched eggs in mother, while paraquat resistant wild animals and the hatched larvae must survive altogether. Second screening Young adult worms were hypochlorited to isolate eggs. The eggs were washed with M9 buffer and resuspended in S buffer. Next day the hatched starved L1 larvae were transferred to NG agar plate including 2 mM paraquat and three days later survivors were scored as animals which had developed into L4 larvae or adults. One of these mutants, mev-1, was investigated for its properties. It was found that mev-1 is about four times more sensitive to this drug than the wild type. Preliminary experiments showed that mev-1 was also more sensitive to exposure to oxygen gas and to Cr(-6). Mev- 1 was found to have a shorter life span as compared with that of the wild type. Namely, the half-life for mev-1 was 8 days at 20 C, while the half-life for the wild type was 12.5 days. It was found that the level of superoxide dismutase (SOD) of mev-1 was about half the level of the wild type. The mev-1 gene was found to be located on linkage group III and fine mapping is in progress now. It is suggested that superoxide anion of which the level in normal cell is delicately controlled by SOD, however the exceeding superoxide anions or lack of SOD must cause cell damages and reduce the life span.