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Effect of weak magnetic fields on animal physiology and behavior
Štefanská, Lucie ; Němec, Pavel (advisor) ; Vácha, Martin (referee)
Weak magnetic fields from different sources constitute a part of the environment, in which animals live. Therefore one can suppose their effect on animal behavior and physiology, including ontogenetic development. The geomagnetic field is ubiquitous and life on Earth has been accompanied by it from the very beginning. Therefore it seems not to be surprising, that diverse animals are able to detect the geomagnetic field and use it as a cue for orientation and navigation, the ability referred to as magnetoreception. Despite being phylogenetically widespread, the transduction mechanisms and the neural basis of magnetoreception and magnetic orientation remain largely unclear. Three major hypotheses are gaining experimental support: mechanisms based on electromagnetic induction, biogenic magnetite and radical pair reactions. In addition to magnetoreception, various other effects of week magnetic fields on organisms have been reported. Most notably, irregular changes of the geomagnetic field (especially geomagnetic storms) and alternating artificial magnetic fields, which have appeared in the environment due to electrification, are considered to have an effect on locomotor activity, learning and memory, nociception, melatonin synthesis and circadian rhythms, cardiovascular system, gene expression and...
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Magnetic orientation in mammals
Tejmlová, Kristýna ; Němec, Pavel (advisor) ; Vácha, Martin (referee)
Earth's magnetic field can provide animal with both directional and positional information. The ability to perceive and utilize information extracted from the geomagnetic field is called magnetoreception. Magnetoreception mechanisms remain largely unknown. Three main hypotheses are currently supported by experimental evidence. The light-independent mechanisms are based either on electromagnetic induction or on biogenic magnetite. The light-dependent mechanism is based on specific chemical reaction between radical pairs. Perception of the geomagnetic field facilitates both long- and short-distance orientation of animals. Some animals exhibit the magnetic alignment, i.e., spontaneuos preference for a certain geomagnetic direction. Another manifestation of magnetoreception is magnetic compass (polarity- or inclination-based, depending on species), which enable an animal to determine the azimuth, i.e., the angle between the direction of motion and geomagnetic field vector. Magnetic map sense enable an animal to determine its position and direction to the goal destination, most likely utilizing the inclination and the intensity of the geomagnetic field as navigational cues. Magnetic orientation of mammals seems to be a widespread phenomenon. Light- independend, polarity compass has been reported in...
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