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Geomagnetic Field Effects on Living Systems

 

experimentally applying no exercise load to the hind limbs of the rat (Jia et al., 2014). Statistical compari­

sons of hindlimb unloading rats were performed between the “hindlimb unloading + HMF” group, in

which the GMF was shielded, and the “hindlimb unloading” group, in which the GMF, was not shielded

(Jia et al., 2014).

As a result, the BMD and BMC of hindlimb unloading rats were further signifcantly reduced by

HMF, and the symptoms of osteoporosis were further exacerbated (Jia et al., 2014). Te results suggest

that HMF may stimulate osteoblasts to secret a receptor activator of nuclear factor-KB ligand (RANKL),

and promote the maturation and activation of osteoclasts, eventually causing bone resorption (Jia et al.,

2014). Tus, it is conceivable that this is because the osteoclasts were out of balance and bone resorption

was promoted by HMF (Jia et al., 2014).

In healthy subjects without cardiovascular pathologies, Gurfnkel et al. (2016) examined the efects

of HMF exposure (±10 nT) on the cardiovascular system and microcirculation and found a signif­

cant increase of the capillary blood velocity, and afer turning of the HMF the capillary blood veloc­

ity returned to the baseline level. HMF exposure signifcantly reduced the heart rate (HR) to the end

of 60-minute exposure to HMF (Gurfnkel et al., 2016). Hypomagnetic conditions also signifcantly

decreased the diastolic blood pressure (DBP) (Gurfnkel et al., 2016). Te capillary blood velocity of all

tested subjects was enlarged by 17%, and the average duration of cardio intervals was increased by 88.7%

during HMF exposure in comparison with sham conditions (Gurfnkel et al., 2016). Tese results dem­

onstrated the efect only for brief exposure to HMF on the cardiovascular system and microcirculation

(Gurfnkel et al., 2016). Gurfnkel et al. (2016) anticipated that during interplanetary missions, long-term

stay in hypomagnetic conditions may have a signifcant impact on the health and working ability of

deep space explorers.

Exposure to an HMF has been found to cause a decrease in amylolytic activity of the intestinal enzymes

and in the activity of proteinases and glycosidases in Crucian carp Carassius carassius (Kuz’mina et al.,

2015). When intracellular Ca²⁺ dependent proteinase (calpains) activity was analyzed following expo­

sure to an HMF a signifcant decrease was observed in calpain activity and Ca²⁺ dependent proteases

were inactivated in Carassius carassius, Rutilus rutilus, and Carassius carpio (Kantserova et al., 2017).

Zhang et al. (2004) found that wild-type Berlin fies raised in an HMF environment continuously for 10

successive generations were gradually signifcantly impaired in visual learning and memory (L/M), and

fnally the tenth generation of HMF fies became completely amnesiac. Te reverse shif from HMF to

natural GMF fully reversed the GMF-free induced amnesia afer more than six consecutive generations.

Te control experiments show that the impairment of L/M could not be ascribed to apparent sensorimotor

problems in HMF fies. Tis study suggests that Drosophila has the potential to develop into a new model

organism for the study of the neurobiology of magnetism for multiple generations (Zhang et al., 2004).

Wan et al. (2014) investigated the efects of HMF on the growth, development, and reproduction of

migratory insects compared with the normal GMF. Two species of nocturnal migratory planthopper,

the small brown planthopper, Laodelphax striatellus, and the brown planthopper, Nilaparvata lugens,

were investigated (Wan et al., 2014). HMF of ~500 nT was generated using the HMF Space System with

MFs of two planthopper species. Te results suggested that exposure of both species to HMF delayed

egg and nymphal developmental durations and decreased adult weight and female fecundity (Wan et al.,

2014). Compared with the GMF, the vitellogenin transcript levels of newly molted female adults and the

number of eggs per female were signifcantly reduced in both species, indicating a negative efect on fer­

tility under HMF (Wan et al., 2014). Overall, N. lugens seemed more sensitive to HMF than L. striatellus

(Wan et al., 2014). It is estimated that HMF may also lead to the titer changes of juvenile hormone and

ecdysone via CRY, i.e., decreased juvenile hormone may downregulate vestigial (Vg) gene expression,

and decreased ecdysone may prolong the nymphal duration (Wan et al., 2014). Tese fndings provided

experimental evidence that HMF negatively afected the growth and development of both species, with

particularly strong efects on reproduction (Wan et al., 2014).

In addition, more recently, Wan et al. (2020a) suggested that the expression of crucial migration-

related traits in N. lugens can respond to changes in the GMF intensity encountered by migratory