Poor geotaxis correlated with haematoporphyrin-induced peroxidation of brain lipids as a predictor of medfly longevity reduction

QUESADA-ALLUÉ, LUIS A.; BOCHICCHIO, PABLO A.; ALEJANDRO RABOSSI

Mendoza

Congreso; X Congreso Argentino de Entomología; 2018

Sociedad Entomológica Argentina

A distinctive feature of ageing is a progressive functional decline, which includes a reduction of adaptive responses to stress with the passage of time. Some behaviours that undergo age-relateddecline such as locomotor activity, geotaxis and circadian rhythms are well known. We previusly estudied the oxidative status in laboratory populations of young and old adults male of Ceratitiscapitata (Wiedemann) (Diptera: Tephritidae). We previously quantified the expression levels of antioxidant response genes by real time PCR, where the catalase and SOD-Mn dropped in old flies.In order to identify early indicators of the accelerated senescence, we evaluated the effects of mild oxidative stress triggered by haematoporphyrin IX (HP IX). We analysed both treatments by invitro and in vivo assays. The metabolism of flies was estimated by oxygen consumption in a ad-hoc respirometer. The lipid content was measured by the vanillin-reagent method. The amount ofglycogen was determined by the Krisman-reagent method assay. We found that exposing flies to HP IX for at least 5 days was sufficient to cause irreversible damage that led to anticipated death.This was also caused by chronic exposure to the same concentration. We demostrated a significant increase in lipid hydroperoxides in brain at day 1 0 after ecdysis, whereas this occurred 5 dayslater in controls. In addition, a significant decrease in glycogen content was observed at 1 5 days, 5 days before the reduction observed in the control group. This decrease has been associatedwith a decline in locomotor activity. The differences in the behaviour of flies in the rearing flasks were documented. An impairment of the motility and climbing capacity of HP IX-treated flies wasdemostrated. This finding was also demostrated by a negative geotaxis response assay (RING). Our results demonstrated that low-lethal oxidative stress can anticipate the initiation ofsenescence, which can be predicted using a simple and fast RING behavioural test