Extremely Low-Frequency Magnetic Fields Induce Developmental Toxicity and Apoptosis in Zebrafish (Danio rerio) Embryos

Abstract

Extremely low-frequency (ELF) magnetic field (MF), as a widespread ecological factor, has an influence on all living beings. In the present study, biological effects of ELF-MF on the development of zebrafish (Danio rerio) embryos were investigated. Fertilized embryos were divided into seven groups as control, sham, and five experimental groups. Embryos of experimental groups were continuously exposed to 50-Hz sinusoidal MF with intensities of 30, 100, 200, 400, and 800 μT for 96 h. The sham group was treated as the experimental groups, but without any ELF-MF exposure. The control group was not subjected to anything. The results showed that ELF-MF exposure caused delayed hatching and decreased heart rate at the early developmental stages of zebrafish embryos, whereas no significant differences in embryo mortality and abnormality were observed. Moreover, acridine orange staining assays showed notable signals of apoptosis mainly in the ventral fin and spinal column. The transcription of apoptosis-related genes (caspase-3, caspase-9) was significantly upregulated in ELF-MF-exposed embryos. In conclusion, the overall results demonstrated that ELF-MF exposure has detrimental effects on the embryonic development of zebrafish by affecting the hatching, decreasing the heart rate, and inducing apoptosis, although such effects were not mortal threat. The results also indicate that zebrafish embryos can serve as a reliable model to investigate the biological effect of ELF-MF.

The Effect of an Anthropogenic Magnetic Field on the Early Developmental Stages of Fishes—A Review

“…A sinusoidal EMF (150 µT, 500 Hz), applied to developing roach ( Rutilus rutilus (L.)) embryos from the moment of fertilization, shortened the duration of embryogenesis, and the embryos hatched earlier compared to the control [ 20 ]. The hatching of zebrafish embryos continuously exposed to 50 Hz sinusoidal fields of 200 µT, 400 µT, and 800 µT 48 h post-fertilization was delayed compared to the control [ 21 ].…”

“…Similarly, no such effect was observed in the sea trout incubated in an SMF (5.5 mT) from fertilization, and the embryos’ survival was even higher [ 11 ]. Sinusoidal MFs (50 Hz) of 30 µT, 100 µT, 200 µT, 400 µT, and 800 µT had no effect on the cumulative mortality and malformation rate in zebrafish ( D. rerio ) embryos [ 21 ]. However, an MF of 500 Hz (1.4–1.6 µT) doubled the embryo mortality [ 24 ].…”

Magnetic fields generated by submarine power cables have a negligible effect on the swimming behavior of Atlantic lumpfish (Cyclopterus lumpus) juveniles

“…Another explanation could be that the MFs affect the cardiac muscle ( Formicki, Korzelecka-Orkisz & Tański, 2019 ). In fish larvae ( Coreganus lavaretus, Atherina boyeri, Salmo trutta, Cyprinus caprio ), high intensity MF causes variations in heart rate, often by increasing it but, depending on the species, also resulting in more chaotic contractions ( Winnicki et al, 2004 ; Li et al, 2014 ; Formicki, Korzelecka-Orkisz & Tański, 2019 ). If lumpfish are indeed magnetosensitive further research is needed to determine how exposure to magnetic anomalies may disrupt their orientation system.…”

Biological Effects of Magnetic Storms and ELF Magnetic Fields

“…Long-term exposure to the ELF-MF f (50)b(500)B(50)t(500 days) accelerated the accumulation of recessive lethal mutations over 40 fruit fly generations [157]. The potential mechanisms of ELF-MF action on embryo survival are increased DNA fragmentation (field f (50)b( 200)B(40)t(48 h)) [159] and/or increased expression of apoptosis inducers caspase-3 and caspase-9 [160]. It is noteworthy, that D. melanogaster embryos' survival rate increases after low induction ELF-MF exposure f (50)b(5-40)B(0.2)t(3 h) [161].…”