Abstract
The ability of an organism to react to unfavorable environmental changes is crucial for survival and reproduction. And decline in that ability may be a result of random damage that is incurred and accumulates throughout the life span of an organism. It has been reported that in fruit flies (Drosophila melanogaster) the damage caused by elevated temperature and γ-ray radiation could shorten the life span and accelerate the rate of aging. We are interested in knowing factors that influence the lethal effect of UV radiation (UVR). In this studying, we used an UV irradiator that provided broad-spectrum UVR (including UVA, UVB and UVC) on adult fruit flies. Our results are summarized as follows. (1) The lethal effect of UVR is influenced by ambient temperature: the survival of flies exposed to 48 h UVR on the 2nd day after eclosion was reduced 12% when the temperature was elevated from 28℃ to 31℃. (2) Young flies are higher in UVR resistance than old flies: resistance in two-day-old flies was 1.5 times that of one-month-old flies. (3) The UVR resistance was found to be inducible in young flies: pretreatment with 15-h UVR on the 2nd day after eclosion resulted in 20% higher survival against a 48-h UVR challenge than that of control.