Coupling Mechanism of Electromagnetic Field and Thermal Stress on Drosophila melanogaster

Temperature is an important factor in research on the biological effects of extremely low-frequency electromagnetic field (ELF-EMF), but interactions between ELF-EMF and temperature remain unknown. The effects of ELF-EMF (50 Hz, 3 mT) on the lifespan, locomotion, heat shock response (HSR), and oxidative stress (OS) of Canton-Special (CS) and mutant w1118 flies were investigated at 25°C and 35°C (thermal stress). Results showed that thermal stress accelerated the death rates of CS and w1118 flies, shortened their lifespan, and influenced their locomotion rhythm and activity. The upregulated expression levels of heat shock protein (HSP) 22, HSP26, and HSP70 indicated that HSR was enhanced. Thermal stress-induced OS response increased malondialdehyde content, enhanced superoxide dismutase activity, and decreased reactive oxygen species level. The effects of thermal stress on the death rates, lifespan, locomotion, and HSP gene expression of flies, especially w1118 line, were also enhanced by ELF-EMF. In conclusion, thermal stress weakened the physiological function and promoted the HSR and OS of flies. ELF-EMF aggravated damages and enhanced thermal stress-induced HSP and OS response. Therefore, thermal stress and ELF-EMF elicited a synergistic effect.

温度是极低频电磁场（extremely low-frequency electromagnetic field, ELF-EMF）生物效应研究中的关键影响因素，但目前极低频电磁场与温度之间的相互作用机制仍未明确。本研究在25℃与35℃（热应激）条件下，探究了50 Hz、3 mT的极低频电磁场对Canton-Special（CS）品系及w1118突变体果蝇的寿命、运动能力、热休克反应（heat shock response, HSR）与氧化应激（oxidative stress, OS）的影响。实验结果显示，热应激可升高CS品系与w1118突变体果蝇的死亡率、缩短其寿命，并影响其运动节律与活动水平。热休克蛋白（heat shock protein, HSP）22、HSP26及HSP70的表达水平上调，提示热休克反应得以增强。热应激诱导的氧化应激反应可提升丙二醛含量、增强超氧化物歧化酶活性，并降低活性氧水平。极低频电磁场还可进一步强化热应激对果蝇死亡率、寿命、运动能力及热休克蛋白基因表达的影响，尤其对w1118品系果蝇的作用更为显著。综上，热应激会削弱果蝇的生理功能，并促进其热休克反应与氧化应激的发生。极低频电磁场会加剧热应激带来的损伤，并强化热应激诱导的热休克蛋白表达与氧化应激反应。由此可见，热应激与极低频电磁场存在协同效应。