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 patterns were determined in wild-type flies, strain Canton S, and the following 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 melatonin formation, due to its inability to express hydroxyindole O-methyltransferase; the mutant rosy (ry 506), which is hypersensitive to oxidants because of its deficiency in the formation of the physiological free-radical scavenger urate. Wild-type flies exhibit a protein carbonyl rhythm of only moderate amplitude; an increase of protein damage is only found in the mid-scotophase. In per s, the nocturnal protein carbonyl maximum of flies kept in LD 12:12 is markedly elevated; additionally, a secondary maximum appears in the middle of photophase. The arrhythmic mutant per 0 does not exhibit diurnal fluctuations, even not in LD. Highest concentrations of protein carbonyl are found in the urate-null mutant ry. Its temporal pattern largely deviates from the those of the other strains by showing highest rates of damage in the morning and during the day.