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Bioelectromagnetism

 

 

populations. Moreover, their results raise the possibility that N. lugens phenotypes vary in response to

changes in the GMF intensity in a manner consistent with predicted trade-ofs between reproduction in

more permanent overwintering habitats in the south and migration to ephemeral northern habitats that

are re-colonized annually as part of the seasonal migration cycle.

Furthermore, in N. lugens, Wan et al. (2020b) found that appetite-related regulatory pathways (neuro­

peptide signaling) and phenotypic outcomes (glucose levels and phloem ingestion) can be infuenced by

changes in the GMF intensity, which is suggested to fnally result in decreases in adult body weight. Te

physiological and behavioral responses of N. lugens to strong changes in the GMF intensity highlight the

GMF’s role in the complicated system of maintaining animal energy homeostasis via appetite regulation

(Wan et al., 2020b). Energy homeostasis is also critical for migratory animals that can undergo large-

scale spatial displacements in a short time (Chapman et al., 2015). Previous works on fueling behavior of

several migratory birds (Fransson et al., 2001; Kullberg et al., 2007; Henshaw et al., 2008) all suggested

that a diference in the GMF intensity between the emigration and immigration areas could be impor­

tant environmental cues for the regulation of biological processes during migration. Tus, the weight

loss suggests an adaptive response of migratory N. lugens to the changes in the GMF intensity during

S-N migration or N-S remigration (Wan et al., 2020b).

It is indicated that endogenous magnetic materials are present in the abdomen of N. lugens (Xie

et al., 2011), as well as that of L. striatellus (Wan et al., 2014). According to the magnetite theory on a

magnetite-based system, long time exposure to HMF may alter the status of clusters of superparamag­

netic crystals anchored to neuronal membranes by cytoskeletal flaments. Tis would be predicted to

deform the membrane, opening or closing ion channels (Johnsen and Lohmann, 2005, 2008; Lohmann,

2010) with potential impacts on the regulation of development and reproduction. Additionally, it has

been reported that HMF can alter circadian rhythm probably through CRY (Zamoshchina et al., 2012).

Terefore, like the “dual receptor magnetoreception hypothesis” (Lohmann, 2010), it is inferred that the

two types of “magnetoreception side efects” respectively related to magnetite and CRY may operate

together to afect the development and reproduction of the insect in the presence of MFs (Wan et al.,

2014). However, it was reported that the absence of the GMF does not infuence the development of the

chick embryo (Janoutova et al., 2000), and therefore, it is supposed that the diferent results likely refect

variation among taxa in sensitivity to MFs (Wan et al., 2014).

Baek et al. (2014) reported that exposure to a specifc ELF-MF (50 Hz, 1 mT) induced epigenetic

changes during cell reprogramming by mediating histone modifcation, whereas an HMF (<5,000 nT)

environment was detrimental to cell fate changes in epigenetic reprogramming (Baek et al., 2014). Here,

three-axis Helmholtz coils were used to generate a zero-feld environment by canceling the GMF (Baek

et al., 2014). Tese results suggested that an HMF environment is critical for epigenetic changes dur­

ing cell fate conversion (Baek et al., 2014). Furthermore, more recently, Baek et al. (2019) investigated

whether HMFs afect cell fate determination during direct diferentiation. Tey found that HMF condi­

tions delayed cell fate conversion during the diferentiation of mouse embryonic stem cells (mESCs),

whereas there were no efects on mESCs in a pluripotent state (Baek et al., 2019). In addition, HMF

conditions reduced the expression of markers corresponding to three germ layers (Pax6, Brachyury,

and Gata4) during mESC diferentiation and reduced embryoid body formation (Baek et al., 2019). Tey

suggested that HMF conditions caused abnormal DNA methylation through the dysregulation of DNA

methyltransferase3b (Dnmt3b) expression, eventually resulting in incomplete DNA methylation dur­

ing diferentiation, and that a specifc ELF-MF is critical for the normal diferentiation of mESCs (Baek

et al., 2019). Terefore, they concluded that ELF-MFs play a role in establishing cellular identity, and

it will be highly interesting to apply ELF-MFs in specifc therapeutic paradigms for which epigenetic

reorganization is a critical outcome (Baek et al., 2019).

Gurhan et al. (2021) investigated the efects of weak SMFs including HMF (0.5 μT) on HT-1080 human

fbrosarcoma cells. Exposures to artifcial SMFs for four consecutive days were varied from 0.5 to 600 μT

for treated units, while exposures to control units were held at 45 μT of the GMF. Cell growth was

signifcantly accelerated between 200 and 400 μT, and in contrast, was signifcantly decreased at 0.5