Biological effects of chronic exposure of Blaptica dubia (Blattodea: Blaberidae) nymphs to static and extremely low frequency magnetic fields

Abstract

In this paper, we analyzed the effects of chronic exposure (5 months) to static magnetic fi eld (110 mT; SMF) and extremely low frequency magnetic fi eld (ELF MF; 10 mT, 50 Hz) on Blaptica dubia nymphs. We have examined acetylcholinesterase (AChE) activity and heat shock protein 70 (HSP70) level, two sensitive biomarkers of stress in terrestrial insects. Relative growth rate (RGR), as a life history trait, was estimated. AChE activity was determined spectrophotometrically and HSP70 levels were quantifi ed using indirect non-competitive ELISA and Western blotting. Calculated RGR was signifi cantly changed upon exposure to both types of ambiental MFs. The effects of chronic exposure of B. dubia nymphs to SMF and ELF MF (50 Hz) were observed as decreased activity of AChE.The increased level of HSP70 was present only after exposure to SMF. The strength of ELF MF was most likely below the energy level needed to induce the expression of this stress protein. Different patterns of the expression of two HSP70 isoforms, where isoform 2 was sensitive only to SMF, are most likely a possibly switch -off in the expression of constitutive and/or inducible HSP70 isoforms.

The impact of chronic exposure to a magnetic field on energy metabolism and locomotion of Blaptica dubia

“…It can be assumed that the same scenario is in the brain of B. dubia nymphs, namely that the applied MFs generate ROS that induce changes in membrane properties and amount of Ca 2+ ions in neurons, including cholinergic. In addition, long-term exposure to both MFs had a direct effect on cholinergic transmission in the brain of B. dubia nymphs causing a decrease in the activity of AChE (Ilijin et al, 2020) and thus excessive ACh accumulation in the synaptic cleft. Having in mind these findings, it is possible that changes in this neurotransmitter determine the behavioral patterns of B. dubia nymphs.…”

“…In light of our recently published finding, an explanation for the observed changes in locomotion should be also sought in the effects of SMF and ELF MF on cholinergic transmission in the brain of B. dubia nymphs (Ilijin et al 2020). In insects, acetylcholine (ACh) is a neurotransmitter involved in the control of locomotion and acetylcholinesterase (AChE) is an enzyme that catalyzes its hydrolysis (Osborne 1996).…”