[Modulation of Ca(2+)-dependent proteinase activity in invertebrates and fish under the action of weak low-frequency magnetic fields]

Molecular Biological Effects of Weak Low-Frequency Magnetic Fields: Frequency-Amplitude Efficiency Windows and Possible Mechanisms

This review covers the phenomenon of resonance-like responses of biological systems to low-frequency magnetic fields (LFMF). The historical development of this branch of magnetobiology, including the most notable biophysical models that explain the resonance-like responses of biological systems to LFMF with a specific frequency and amplitude, is given. Two groups can be distinguished among these models: one considers ion-cofactors of proteins as the primary targets for the LFMF influence, and the other regards the magnetic moments of particles in biomolecules. Attention is paid to the dependence of resonance-like LFMF effects on the cell type. A radical-pair mechanism of the magnetic field's influence on biochemical processes is described with the example of cryptochrome. Conditions for this mechanism's applicability to explain the biological effects of LFMF are given. A model of the influence of LFMF on radical pairs in biochemical oscillators, which can explain the frequency-amplitude efficiency windows of LFMF, is proposed.

Influence of Calcium Resonance-Tuned Low-Frequency Magnetic Fields on Daphnia magna

A biophysical model for calculating the effective parameters of low-frequency magnetic fields was developed by Lednev based on summarized empirical data. According to this model, calcium ions as enzyme cofactors can be the primary target of low-frequency magnetic fields with different parameters tuned to calcium resonance. However, the effects of calcium-resonant combinations of static and alternating magnetic fields that correspond to Lednev's model and differ by order in frequency and intensity were not studied. It does not allow for confidently discussing the primary targets of low-frequency magnetic fields in terms of the magnetic influence on ions-enzyme cofactors. To clarify this issue, we examined the response of freshwater crustaceans Daphnia magna to the impact of combinations of magnetic fields targeted to calcium ions in enzymes according to Lednev's model that differ in order of magnitude. Life-history traits and biochemical parameters were evaluated. Exposure of daphnids to both combinations of magnetic fields led to a long-term delay of the first brood release, an increase in the brood size, a decrease in the number of broods, and the period between broods. The amylolytic activity, proteolytic activity, and sucrase activity significantly decreased in whole-body homogenates of crustaceans in response to both combinations of magnetic fields. The similarity in the sets of revealed effects assumes that different magnetic fields tuned to calcium ions in biomolecules can affect the same primary molecular target. The results suggest that the low-frequency magnetic fields with parameters corresponding to Lednev's model of interaction between biological molecules and ions can remain effective with a significant decrease in the static magnetic background.

[Modulation of Ca(2+)-Dependent Proteiolysis under the Action of Weak Low-Frequency Magnetic Fields]

The study aimed to determine the molecular targets of magnetic fields in living objects. Time-dependent effects of weak low-frequency magnetic field tuned to the parametric resonance for calcium ions were studied on model organisms (fish, whelk). The dynamics of Ca(2+)-dependent proteinase activity under the exposure to magnetic fields with given parameters was determined and minimal time of exposure in order to achieve inactivation of these proteinases was find out as well. As hyperactivation of Ca(2+)-dependent proteinases is a basis of degenerative pathology development the therapeutic potential of weak low-frequency magnetic fields enabling to modulate Ca(2+)-dependent proteinase activity is supported.

Delayed consequences of extremely low-frequency magnetic fields and the influence of adverse environmental conditions on roach Rutilus rutilus embryos

This study presents data collected over a 6 year period on the effects of extremely low-frequency magnetic fields (MFs) (1.4-1.6 µT, 500 Hz and 1.4-1.6 µT, 72.5 Hz) and MFs in combination with other environmental stressors (elevated temperature, 0.01 mg l(-1) trichlorfon, 0.01 mg l(-1) copper sulphate pentahydrate) on roach Rutilus rutilus embryos. Effects were studied during different stages of early development. Rutilus rutilus were raised in ponds for 4 months after exposure to MFs. The mass, standard length (LS ) and morphological characteristics of underyearlings which were exposed as embryos were recorded. An increase in embryo mortality and a decrease in LS and mass indices in underyearlings were noted after they had been exposed to a combination of MFs and different adverse environmental factors. In addition, exposure to MFs led to changes in the total number of vertebrae and the number of seismosensory system openings in the mandibular bones of underyearlings. MFs of different frequency caused both increases (500 Hz) and decreases (72.5 Hz) in morphological diversity. The stressors used in this study, however, did not increase the fluctuating asymmetry of bilateral morphological characteristics. The possible microevolutionary effects of exposure to MFs alone and in combination with other adverse environmental factors upon natural fish populations are discussed.