Vol. 11, No. 2
MOLECULAR AND CELLULAR BIOLOGY, Feb. 1991, p. 632-640
0270-7306/91/020632-09$02.00/0 Copyright C 1991, American Society for Microbiology
Expression of Bovine Superoxide Dismutase in Drosophila melanogaster Augments Resistance to Oxidative Stress I. REVEILLAUD,l A. NIEDZWIECKI,l K. G. BENSCH,2 AND J. E. FLEMING'* Sasakawa Center for Aging Research, Linus Pauling Institute of Science and Medicine, 440 Page Mill Road, Palo Alto, California 94306,1 and Department of Pathology, Stanford University School of Medicine, Stanford, California 943052 Received 6 July 1990/Accepted 1 November 1990
Superoxide dismutases (SOD) play a major role in the intracellular defense against oxygen radical damage to aerobic cells. In eucaryotes, the cytoplasmic form of the enzyme is a 32-kDa dimer containing two copper and two zinc atoms (CuZn SOD) that catalyzes the dismutation of the superoxide anion (02) to H202 and 02 Superoxide-mediated damage has been implicated in a number of biological processes, including aging and cancer; however, it is not certain whether endogenously elevated levels of SOD will reduce the pathological events resulting from such damage. To understand the in vivo relationship between an efficient dismutation of 02 and oxidative injury to biological structures, we generated transgenic strains of Drosophila melanogaster overproducing CuZn SOD. This was achieved by microinjecting Drosophila embryos with P-elements containing bovine CuZn SOD cDNA under the control of the Drosophila actin Sc gene promoter. Adult flies of the resulting transformed lines which expressed both mammalian and Drosophila CuZn SOD were then used as a novel model for evaluating the role of oxygen radicals in aging. Our data show that expression of enzymatically active bovine SOD in Drosophila flies confers resistance to paraquat, an 02-generating compound. This is consistent with data on adult mortality, because there was a slight but significant increase in the mean lifespan of several of the transgenic lines. The highest level of expression of the active enzyme in adults was 1.60 times the normal value. Higher levels may have led to the formation of toxic levels of H202 during development, since flies that died during the process of eclosion showed an unusual accumulation of lipofuscin (age pigment) in some of their cells. In conclusion, our data show that free-radical detoxification has a minor but positive effect on mean longevity for several strains.
gation focuses on cytoplasmic SOD. In eucaryotes, the cytoplasmic form of the enzyme, a 32-kDa dimer with two copper and two zinc atoms (CuZn SOD), catalyzes the dismutation of the superoxide anion (02-) to hydrogen peroxide and molecular oxygen (24, 25). As expected, organisms with mutations in the SOD gene are more susceptible to a variety of oxidative stresses (29, 30). Thus, much of the recent research on the causal relationship between oxygen toxicity and senescence, at least in Drosophila melanogaster, has focused on the study of mutant strains that underexpress SOD or catalase (23, 29, 30). Phillips et al. have recently reported that a strain of D. melanogaster carrying a null mutation for cytoplasmic SOD has a reduced lifespan, adult infertility, and increased sensitivity to paraquat. Also, Mackay and Bewley described acatalasemic Drosophila mutants with reduced viability (23, 30). However, they also observed that even though very low levels of catalase activity (
MOLECULAR AND CELLULAR BIOLOGY, Feb. 1991, p. 632-640
0270-7306/91/020632-09$02.00/0 Copyright C 1991, American Society for Microbiology
Expression of Bovine Superoxide Dismutase in Drosophila melanogaster Augments Resistance to Oxidative Stress I. REVEILLAUD,l A. NIEDZWIECKI,l K. G. BENSCH,2 AND J. E. FLEMING'* Sasakawa Center for Aging Research, Linus Pauling Institute of Science and Medicine, 440 Page Mill Road, Palo Alto, California 94306,1 and Department of Pathology, Stanford University School of Medicine, Stanford, California 943052 Received 6 July 1990/Accepted 1 November 1990
Superoxide dismutases (SOD) play a major role in the intracellular defense against oxygen radical damage to aerobic cells. In eucaryotes, the cytoplasmic form of the enzyme is a 32-kDa dimer containing two copper and two zinc atoms (CuZn SOD) that catalyzes the dismutation of the superoxide anion (02) to H202 and 02 Superoxide-mediated damage has been implicated in a number of biological processes, including aging and cancer; however, it is not certain whether endogenously elevated levels of SOD will reduce the pathological events resulting from such damage. To understand the in vivo relationship between an efficient dismutation of 02 and oxidative injury to biological structures, we generated transgenic strains of Drosophila melanogaster overproducing CuZn SOD. This was achieved by microinjecting Drosophila embryos with P-elements containing bovine CuZn SOD cDNA under the control of the Drosophila actin Sc gene promoter. Adult flies of the resulting transformed lines which expressed both mammalian and Drosophila CuZn SOD were then used as a novel model for evaluating the role of oxygen radicals in aging. Our data show that expression of enzymatically active bovine SOD in Drosophila flies confers resistance to paraquat, an 02-generating compound. This is consistent with data on adult mortality, because there was a slight but significant increase in the mean lifespan of several of the transgenic lines. The highest level of expression of the active enzyme in adults was 1.60 times the normal value. Higher levels may have led to the formation of toxic levels of H202 during development, since flies that died during the process of eclosion showed an unusual accumulation of lipofuscin (age pigment) in some of their cells. In conclusion, our data show that free-radical detoxification has a minor but positive effect on mean longevity for several strains.
gation focuses on cytoplasmic SOD. In eucaryotes, the cytoplasmic form of the enzyme, a 32-kDa dimer with two copper and two zinc atoms (CuZn SOD), catalyzes the dismutation of the superoxide anion (02-) to hydrogen peroxide and molecular oxygen (24, 25). As expected, organisms with mutations in the SOD gene are more susceptible to a variety of oxidative stresses (29, 30). Thus, much of the recent research on the causal relationship between oxygen toxicity and senescence, at least in Drosophila melanogaster, has focused on the study of mutant strains that underexpress SOD or catalase (23, 29, 30). Phillips et al. have recently reported that a strain of D. melanogaster carrying a null mutation for cytoplasmic SOD has a reduced lifespan, adult infertility, and increased sensitivity to paraquat. Also, Mackay and Bewley described acatalasemic Drosophila mutants with reduced viability (23, 30). However, they also observed that even though very low levels of catalase activity (
