Diurnal rhythm of protein carbonyl as an indicator of oxidative damage in Drosophila melanogaster: Influence of clock gene alleles and deficiencies in the formation of free-radical scavengers

In males of Drosophila melanogaster, protein carbonyl was determined as an indicator of damage by free radicals; this parameter was chosen because it is not affected by self-sustaining progression of radical reaction chains, in contrast to indicators based on lipid peroxidation. The diurnal time pat terns were determined in wild-type flies, strain Canton S, and the followin g mutants, on a Canton S genetic background: the short-period mutant per(s) ; the arrhythmic mutant per(0), which is, at the same time, deficient for m elatonin formation, due to its inability to express hydroxyindole O-methylt ransferase; the mutant rosy (ry(506)), which is hypersensitive to oxidants because of its deficiency in the formation of the physiological free-radica l scavenger urate. Wild-type flies exhibit a protein carbonyl rhythm of onl y moderate amplitude; an increase of protein damage is only found in the mi d-scotophase. In per(s), the nocturnal protein carbonyl maximum of flies ke pt in LD 12:12 is markedly elevated; additionally, a secondary maximum appe ars in the middle of photophase. The arrhythmic mutant per(0) does not exhi bit diurnal fluctuations, even not in LD. Highest concentrations of protein carbonyl are found in the urate-null mutant ry. Its temporal pattern large ly deviates from the those of the other strains by showing highest rates of damage in the morning and during the day.