Fig. 4. parkin null flies have reduced longevity and stress resistance. We analyzed life span, and oxidative and cold stress resistance of parkin mutant animals. (A) Longevity profile of w; dpk²¹ as well as w; dpk²¹/Df(3L)pc-MK animals. The Df(3L)pc-MK deficiency uncovers the entire parkin locus. Mean life span for male w; dpk²¹ flies is 13 days and for w; dpk²¹/Df(3)pc-MK flies is 32 days, compared with more than 60 days for heterozygous controls. Similar results were observed with females. (B) Paraquat sensitivity of parkin mutants. Loss of parkin results in rapid mortality when flies are maintained on 2 mM paraquat-containing media. (C) Cold stress resistance test. parkin mutants exhibit poor survival at 4°C. Fifty flies per genotype per sex were analyzed for each assay. Similar results were obtained with w; dpk^P23 and w; dpk^P24 mutants.