Exposure to Cigarette Smoke Increases Urate Level and Decreases Glutathione Level in Larval Drosophila melanogaster

Abstract

Recently, we reported experimental evidence to support the notion that in Drosophila melanogaster, urate is involved in defense against toxic eŠects of environmental cigarette smoke (ECS). To obtain further information pertaining to the defense mechanisms involving urate and other antioxidants, the present study measured the levels of urate, its precursors and glutathione, and SOD activity in larval ‰ies of wild-type strains (Oregon-R and Canton-S) and two urate-null mutant strains (ma-l and ry 1 ) following exposure to ECS for various durations. In both wild type strains, unlike the case in either of the mutant strains, the urate level signiˆcantly increased above the basal level in a manner dependent on the duration of ECS exposure. Similar increases in the level of urate precursors were found in Canton-S and in both of the urate-null strains. There was a slight increase in glutathione level above the control level following ECS exposure for a short time, followed by an exposure-dependent decrease to less than 60% of the control level within the exposure range used in all of the four strains. On the other hand, no appreciable change was found in the SOD activity prior to or following ECS exposure, irrespective of the strain examined. In terms of the survival of treated larvae to adulthood under the conditions used for the measurements of urate and others, it was found that wild-type strain Canton-S was as sensitive as the urate-null mutant strains and clearly more sensitive than wild-type strains Oregon-R and Hikone-R. This was so despite the fact that, compared with Oregon-R, Canton-S contained urate at relatively higher levels prior to and following ECS exposure, and that the glutathione levels in Canton-S prior to and following treatment were comparable with those in other strains. These results are discussed with respect to the involvement of urate and glutathione in defense against the toxicity of ECS and the possible existence of another defense mechanism which is deˆcient in the Canton-S strain.

Increase of somatic cell mutations in oxidative damage-sensitive drosophila

“…The lack of uric acid and an increase in its precursors were confirmed in mwh , ry 506 / ry 506 female flies using HPLC [ 16 ]; the content of uric acid in body fluid was 0.35 nmol/mg protein, that of hypoxanthine was 48.1 nmol/mg protein, and that of xanthine was 57.6 nmol/mg protein. Similarly, the lack of uric acid and an increase in its precursors has been confirmed in ma-l / ma-l ; mwh female flies in a previous report [ 10 ]; the content of uric acid was 0.4 ± 0.3 nmol/mg protein, that of hypoxanthine was 43.2 ± 22.4 nmol/mg protein, and that of xanthine was 35.1 ± 11.7 nmol/mg protein. Statistical analysis of the wing-spot test results was performed using χ 2 test described by Frei and Würgler [ 17 ] when total number of spots to be compared each other was one hundred and over, and using the tables shown by Kastenbaoum and Bowman [ 18 ] when total number of spots was under one hundred.…”

“…The strain represented by ry 506 is a mutant of the rosy gene on the third chromosome that is deficient in XDH activity due to a deletion in its gene [ 6 ]. In these urate-null mutants, the lack of uric acid and the accumulation of its precursors (xanthine and hypoxanthine) were confirmed by measuring the contents in the body fluid of both adult flies and larvae [ 9 , 10 ]. The strain ry + is speculated to be a revertant whose uric acid synthesis activity had recovered during breeding of ry 506 in our laboratory (the uric acid content was 4.4 ± 1.1 nmol/mg protein, compared to 4.8 ± 0.8 nmol/mg protein in wild-type Oregon-R larvae).…”

“…ROS and radicals cause DNA damage that can lead to diseases, including cancer [ 8 ]. Previously, we reported that urate-null Drosophila mutants were sensitive to the toxicity of environmental cigarette smoke (ECS) [ 9 , 10 ], and that the effects of the ECS were apparent even in the next generation [ 10 ]. We also reported that somatic cell mutations were induced by ECS and the herbicide paraquat in urate-null Drosophila , but not in wild-type Drosophila [ 11 ].…”

Association of urinary cotinine-verified smoking status with hyperuricemia: Analysis of population-based nationally representative data

“…Finally, physiologic response to oxidative stress from cigarette smoking could also explain the negative influence of smoking on serum uric acid levels. Because uric acid has anti-oxidative effects, oxidative stress caused by reactive oxygen species from tobacco smoking components results in increased uric acid production to counteract these oxidative agents 34 .…”

Mutation and apoptosis are well-coordinated for protecting against DNA damage-inducing toxicity in Drosophila

“…The experiments on the exposure to tobacco smoke were performed according to our previous reports using an oxidative stress-sensitive Drosophila strain [31][32][33]. Approximately 500 third instar larvae in 0.25 M sucrose were placed in a plastic box with a nylon mesh cover, and were continuously exposed to tobacco smoke from three burning cigarettes for 6 h at 25 °C in an incubator (IJ300W, Yamato Scientific Co., Ltd., Tokyo, Japan).…”