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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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Sensitivity to magnetic field in Mexican Cavefish
JANDA, Patrik
This thesis deals with the detection of magnetic field perception of cavefishes the Mexican tetra (Astyanax mexicanus). The experiments were carried out in a plus-shaped maze where the direction preference in the individual arms of this maze was studied both in the natural Earth´s magnetic field and in the modified one by using magnets and turning the north-south axis by 90°. The reactions of the specimen on placing a strong magnet close behind the end of the western and later also the eastern arm of the plus-shaped maze were also monitored. It was conclusively found that the Mexican tetra prefer north-south axis. However, after turning the magnetic field by 90° there was no preference of the specimen for the new north-south axis as we expected. Although some of the tests performed here show the perceptiveness of magnetic field of the Mexican tetra and their preference for the noth-south axis, other tests disprove the formulated hypothesis. That is why other new hypotheses about the perceptiveness of the magnetic field should be created so that they could not be disproved in either case. This thesis has served as a stepping stone for further research in the field of magnetoreception of cavefishes.
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Neural Basis of magnetic compass orientation in C57BL/6J mice
Bláhová, Veronika ; Němec, Pavel (advisor) ; Druga, Rastislav (referee)
The ability to perceive the Earth's magnetic field has been demonstrated in a variety of animals, including representatives of all five classes of vertebrates. The physiological mechanisms underlying magnetic field sensation, however, remain largely unknown. Behavioral, physiological, neuroethological studies and studies using early response genes as neuronal activation markers indicated that a major role in the perception and processing of magnetic information play trigeminal, vestibular and visual systems. Subsequently, magnetic information seem to be integrated with multimodal sensory and motor information within the hippocampal-entorhinal system. In the majority of studies, however, birds have been used as model organisms. In this work I analyzed the neural substrate of magnetic compass orientation in the mouse strain C57BL/6J using markers c-Fos and Egr1. I found that all the aforementioned systems contain neurons responsive to the experimental magnetic fields. This finding demonstrates a complex processing of the magnetic information at level of the central nervous system.
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Ověření magnetické orientace u savců
KOČANDRLOVÁ, Barbora
Thesis is monitoring body orientation during the day cycle, with a special focus on the body orientation during resting and grazing cattle. Environmental conditions including the Earth's magnetic field which affect the animal orientation have been evaluated. Body orientation of the selected individuals was determined by compass, directly every half hour at the site. In total 24 cows in 2 herds were monitored. In every herd were chosen 12 easily recognizable individuals. Monitoring took place 7 days in September 2016. About weather conditions (wind, rain, sun, temperature) and resting of the individuals was kept an account, which would affect the cattle orientation. This study could not confirm the theory of the N-S cattle orientation by magnetic field and therefore can not confirm or disprove the influence of the power line to the cattle orientation. Even at rest or grazing cattle the theory of the N-S orientation could not be confirmed.
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Stanovení pozičního chování savců se zaměřením na magnetické pole Země
FOLEJTAROVÁ, Lucie
Currently, much attention is paid to magnetoreception, a sense which allows an organism to detect a magnetic field of the earth. Now, this discovery is related to positional behaviour of animals (magnetic alignment) in the magnetic field and the world phenomenon of "magnetic cows". The magnetic alignment is a spontaneous (congenital) behaviour, when the animal puts its body axis into the positions of north - south or east - west. Most studies have demonstrated the north - south direction preference. This work contributes to clarify positional behaviour of cattle during the daily cycle. This study is based on a different data collection and is targeted at individuals in the herd. Individuals were photographed in a given direction, at hourly intervals. The magnetic alignment was determined in 26 individuals from three different cattle herds, mainly east or west. Statistically significant results during daily cycles in individual intervals also confirmed the north - south direction preference. There were also discussed the environmental conditions that may affect the final result. For inconclusive results, the individuals were probably motivated by temporarily more important local incentives.
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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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Circadian clock genes in insects
BAZALOVÁ, Olga
This thesis focuses on molecular characterization of circadian clock genes in insects. It explores genetic diversity of circadian clock genes by molecular characterization of several insect species including two dipteran flies (Musca domestica and Drosophila melanogaster), two cockroach species representing ancestral insects, and the linden bug, Pyrrhocoris apterus. Furthermore it considers various roles of circadian clock genes in insect physiology. Application of molecular-biology methods in Pyrrhocoris apterus, non-model insect species, enable us to investigate involvement of circadian clock genes in photoperiod induced physiological responses. Application of molecular-biology methods in Periplaneta americana and Blattella germanica was used to explore involvement of circadian clock genes in magnetoreception.
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The influence of geomagnetism on the behavior of dogs
PLACHOVÁ, Denisa
The aim of this bachelor thesis was to evaluate the influence of geomagnetism on the dog. The theoretical part contains information from technical literature and articles concerning the ability of different species (from primitive organisms to large mammals) perceive the Earth's magnetic field and use it for their orientation and navigation. The practical part deals with own observation of the dog of the breed called pug, when was watched the spontaneous directional orientation of the dog during feeding, resting and excreting. Monitoring was carried out in a few months and the only tool, which was used was the compass, by which was recorded the direction in which the head of the dog was oriented during the individual activities. All measured values were entered into the tables created in Microsoft Excel spreadsheet and after that were statistically evaluated. From the evaluated data emerged that the dog during each of the monitored activity exhibited some directional preference. When feeding the dog preferred axis NW/SE, when resting S/SE direction and during excretion preferred axis NW/SE.
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Magnetic orientation in the bank vole (\kur{Myodes glareolus})
NOVÁKOVÁ, Monika
The magnetic orientation was established in several species of rodents, but the mechanism of its perception has not been determined. Aim of this work was to verify magnetic sense in the bank vole (Myodes glareolus) and try to solve the nature of its magnetoreception in tests carried out in total darkness and when the horizontal component was reversed and the vertical component was inverted. A spontaneous directional preference in the magnetic field was tested in circular arena.
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Function of retina of Homing pigeon \kur{Columba livia} in magnetoreception
BAJGAR, Adam
Many animals have ability to percieve the magnetic field of the Earth and use this clue for both orientation and navigation. Yet little is known about physiological mechanism that underlies this sensory ability. Although physiological mechanism still remains unclear, there are three major hypotheses how animals can detect the magnetic field. In this study I focused on the radical pair theory. I analyzed how manipulation of the ambient magnetic field influence the expression of CRY 1, CRY 2 and c-Fos in the pigeon´s retina. I observed in incerased numbers of CRY1, c-Fos and CRY1+c-Fos possitive cells in the ihned nuclear layer (INL) of the retina in animals sbjected to the periodical manipulation of the magnetic field inclination. These data demonstrate that the INL constains a population of neurons that are responsive to magnetic stimuli and strongly suggest that Cry 1 is involved in detection of the Earth magnetic field.
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