The Role of Hsp70 Genes in Promoting Control of Viability in Drosophila melanogaster Subjected to Microwave Irradiation

Abstract: Biological effects produced by low-energy electromagnetic radiation were often explained by transcriptional induction of the Hsp70 gene. In this study, we investigated a series of important adaptation traits developed in Drosophila melanogaster strains with different copy numbers of Hsp70 genes when subjected to microwave irradiation. In our experiments, we used mutant strains with gene deletion in all or several Hsp70 copies. The wild-type strain (Canton-S containing the full set of Hsp70 genes in its genome) was used as a control. Electromagnetic radiation (power density10 μW/cm², frequency 37.7 GHz and 65.0 GHz, exposure duration 5 min) was used for the irradiation of adult flies (imago). The experimental results showed that exposure to microwave radiation produced no effect on the number of the wild-type offspring (Canton-S with the full set of Hsp70 genes) by the pupal stage and imago but was accompanied by increased embryonic mortality and an increased median lifespan. In most cases, exposure to microwave radiation led to adverse effects on the viability of strains without all copies or with the presence of one copy of Hsp70 genes. In these strains, the external influence resulted in a lower number of offspring by the imago, an increased number of dead individuals during the pupal and early stages of imago development, and a decrease in the median and maximum lifespan of the imago. Interestingly, when the strain containing four copies of Hsp70 was exposed to microwave radiation it was found that individuals tend to show sexual dimorphism in response to such an external influence: a decrease in the median and maximum lifespan of the female imago and an increase of the lifespan of the male flies. The results of this study demonstrate the importance of the presence of the full set of Hsp70 genes in the Drosophila genome to adapt to microwave radiation.