Response of aquatic protists to electric field exposure

Abstract

Purpose: To test the effects of short-term exposure of aquatic organisms to electric field (EF) with negligible magnetic component.

Materials and methods: We built a plate capacitor that served as a source of EF of strengths that can be found in nature near transmission lines. We exposed two cultured protist species Euglena viridis and Paramecium caudatum to EFs for 24 hours and monitored their abundance, morphology, intracellular superoxide anion (by dihydroethidium [DHE]), hydrogen peroxide by (H₂DCF) and lipid peroxidation (MDA) contents, catalase (CAT) and superoxide dismutase (SOD) activity.

Results: We found that even short-term exposure to low strength EF causes changes in population abundance, morphology and oxidative stress response in both species. As the EF strength increased, abundance of both species decreased. However, at weaker EFs, fission rates were seemingly promoted. We noted a decrease in size in both organisms in directions perpendicular to their fission planes correlated with EF strength. DHE and H₂DCF fluorescence intensity and SOD activity were higher in organisms exposed to the stronger EFs.

Conclusions: We suggest that the electric component of the field, rather than the magnetic, is the main cause of all the noted effects. As a result, aquatic organisms should be given greater importance in studies assessing the effects of EMFs in spite of the attenuating effects of water to EF strengths.

Keywords:

• ROS
• SOD
• Euglena
• Paramecium
• plate capacitor
• Croatia

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Notes on contributors

Marko Miliša, PhD, an Assistant Professor of invertebrate biology and ecology at the Division of Zoology, Department of Biology, Faculty of Science, University of Zagreb, together with Ana Ostojić, PhD, from the same laboratory, conducted the experiments with population density and morphology of Paramecium and Euglena.

Professor Domagoj Đikić, PhD, is a Professor of comparative animal physiology, metabolism and toxicology, expert in the field of cellular redox physiology, at the Department of Animal Physiology, Biology Divison of the Faculty of Science, University of Zagreb, and conducted the biochemical and fluorescence microscopy measurements, together with Ivan Čolić, MSc, from the same department.

Tvrtko Mandić, PhD, a Research Associate at the Department of Electronics, Microelectronics, Computer and Intelligent Systems of the Faculty of Electrical Engineering and Computing, University of Zagreb, together with graduate student Dino Grozić, conducted the plate capacitor construction and measurements of the conditions of the electrical field.

Additional information

Funding

This work was supported by the Ministry of Science and Technology, Croatia, through the project BIOECO CROMON, led by the corresponding author Prof. D. Đikić.