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Bioelectromagnetism

 

for the biological and health efects and medical applications of electromagnetism, is shown. Chapter 2

presents how bioelectromagnetism has been gradually developing and expanding into a variety of felds

such as engineering, biomedical engineering, medicine and biology. Tis chapter also explains the fan­

tastic and dramatic history of bioelectromagnetism from ancient times until the twenty-frst century.

It chronologically details the history of the major subjects, the moments when scientists made relevant

physical, chemical, electrical and biological discoveries, and a historical debate about possible human

health efects due to exposure to electromagnetic felds. Tis chapter also includes, as far as possible, the

historical development of Japanese research in bioelectromagnetism. Te main emphasis of this chapter

is to present how through the long historical development of bioelectromagnetism, today’s scientifc

achievements in biomedical engineering, biology, medicine, etc. were shaped by elucidating the electro­

magnetic phenomena found in biological systems.

Chapters 3 and 6 will establish the introduction regarding the connection between atmospheric elec­

tricity, geomagnetic feld and biological systems, and the relationship between the evolutions of life with

the geomagnetic felds. As was already indicated, the electromagnetic phenomena of the atmospheres

have afected the evolution of life. Furthermore, the evolution of life has also been afected by the fuctu­

ations and variations of the geomagnetic feld intensity as well as by changes in atmospheric oxygen lev­

els and UV radiation. It has been estimated that following a geomagnetic feld reversal, the geomagnetic

feld becomes weaker, and its reduction in the last 200 years has been substantial. Also, the earth’s mag­

netic poles are moving, and it is estimated that the north pole has moved 1,100 km over the last 170 years.

Furthermore, predictions based on simulations estimate that geomagnetic feld reversals can enhance

the oxygen escape rate by 3–4 orders if the magnetic feld becomes sufciently weak. Consequently, it is

anticipated that the global hypoxia will gradually kill numerous species. Chapter 6 comprises fascinat­

ing topics regarding the “Cambrian explosion of life,” the “extinction of Neanderthals,” the “magnetic

feld defciency syndrome,” and the “magnetic storm and its related diseases,” all of which are possible

results of geomagnetic fuctuations.

Chapters 4 and 5 will present the recent advances in magnetobiology. Magnetobiology, a part of bio-

electromagnetism, studies living systems’ sensitivity to weak magnetic felds, such as magnetic naviga­

tion, magnetotactic bacteria, and the magnetic response of plants, birds, animals and humans. Both

chapters focus on the magnetic navigation of birds and the magnetoreception in plants. Chapter 4 intro­

duces the role of magnetic sensing in the migration of birds. Recently, the possibility that cryptochromes

serve as highly sensitive magnetoreceptors has been strongly suggested, and several research felds such

as quantum biology are actively paying attention to this functional characteristic. Te research of this

characteristic is also important because the blue-light photoreceptor protein, cryptochrome, which

includes FAD, is widely found in nature, i.e., bacteria, plants and animals. Magnetic sensing is presumed

to be the consequence of the reaction between FAD with the amino acid residue as the intermediate by

photoirradiation, i.e., the radical pair mechanism for quantum-assisted magnetic sensing, which is able

to detect weak magnetic felds such as the geomagnetic feld (approximately 50 μT). By means of these

magnetoreceptors found in their retina, the migratory birds are assumed to visually perceive in which

direction to move. Tis chapter reviews historical background in theoretical physics and ethology, and

outstanding results in several research felds to date. Chapter 5 introduces the magnetic sensing capabil­

ity of plants. Efects of the geomagnetic feld have been observed in plants. However, the impact of the

geomagnetic feld on plant is still not well-understood and the magnetoreception mechanism in plants

is still not scientifcally conclusive. Te two main models for magnetoreception are the magnetite model

and the radical pair model. Te radical pair model is linked to cryptochrome, in a way similar to the

magnetoreceptors found in migratory birds. It was previously mentioned that cryptochromes are a class

of favor-proteins sensitive to light that are found in a variety of plants and animals. Phytochrome and

phototropin are also photoreceptor proteins found in plants. Magnetic feld efects in plants are also

related to light-dependent plant processes. In this chapter, the efects of the geomagnetic feld on plants

are reviewed and the possible mechanisms of magnetoreception in plants including the involvement of

photoreceptors are discussed.