| 1. |
- Landler, Lukas, et al.
(författare)
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Ectosymbionts alter spontaneous responses to the Earth’s magnetic field in a crustacean
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic sensing is used to structure every-day, non-migratory behaviours in many animals. We show that crayfish exhibit robust spontaneous magnetic alignment responses. These magnetic behaviours are altered by interactions with Branchiobdellidan worms, which are obligate ectosymbionts. Branchiobdellidan worms have previously been shown to have positive effects on host growth when present at moderate densities, and negative effects at relatively high densities. Here we show that crayfish with moderate densities of symbionts aligned bimodally along the magnetic northeast-southwest axis, similar to passive magnetic alignment responses observed across a range of stationary vertebrates. In contrast, crayfish with high symbiont densities failed to exhibit consistent alignment relative to the magnetic field. Crayfish without symbionts shifted exhibited quadramodal magnetic alignment and were more active. These behavioural changes suggest a change in the organization of spatial behaviour with increasing ectosymbiont densities. We propose that the increased activity and a switch to quadramodal magnetic alignment may be associated with the use of systematic search strategies. Such a strategy could increase contact-rates with conspecifics in order to replenish the beneficial ectosymbionts that only disperse between hosts during direct contact. Our results demonstrate that crayfish perceive and respond to magnetic fields, and that symbionts influence magnetically structured spatial behaviour of their hosts.
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| 2. |
- Phillips, John B., et al.
(författare)
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Rapid Learning of Magnetic Compass Direction by C57BL/6 Mice in a 4-Armed 'Plus' Water Maze
- 2013
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:8
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Tidskriftsartikel (refereegranskat)abstract
- Magnetoreception has been demonstrated in all five vertebrate classes. In rodents, nest building experiments have shown the use of magnetic cues by two families of molerats, Siberian hamsters and C57BL/6 mice. However, assays widely used to study rodent spatial cognition (e.g. water maze, radial arm maze) have failed to provide evidence for the use of magnetic cues. Here we show that C57BL/6 mice can learn the magnetic direction of a submerged platform in a 4-armed (plus) water maze. Naive mice were given two brief training trials. In each trial, a mouse was confined to one arm of the maze with the submerged platform at the outer end in a predetermined alignment relative to magnetic north. Between trials, the training arm and magnetic field were rotated by 180 degrees so that the mouse had to swim in the same magnetic direction to reach the submerged platform. The directional preference of each mouse was tested once in one of four magnetic field alignments by releasing it at the center of the maze with access to all four arms. Equal numbers of responses were obtained from mice tested in the four symmetrical magnetic field alignments. Findings show that two training trials are sufficient for mice to learn the magnetic direction of the submerged platform in a plus water maze. The success of these experiments may be explained by: (1) absence of alternative directional cues (2), rotation of magnetic field alignment, and (3) electromagnetic shielding to minimize radio frequency interference that has been shown to interfere with magnetic compass orientation of birds. These findings confirm that mice have a well-developed magnetic compass, and give further impetus to the question of whether epigeic rodents (e.g., mice and rats) have a photoreceptor-based magnetic compass similar to that found in amphibians and migratory birds.
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| 3. |
- Phillips, John, et al.
(författare)
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Why is it so difficult to study magnetic compass orientation in murine rodents?
- 2022
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Ingår i: Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology. - : Springer Science and Business Media LLC. - 0340-7594. ; 208:1, s. 197-212
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Forskningsöversikt (refereegranskat)abstract
- A magnetic compass sense has been demonstrated in all major classes of vertebrates, as well as in many invertebrates. In mammals, controlled laboratory studies of mice have provided evidence for a robust magnetic compass that is comparable to, or exceeds, the performance of that in other animals. Nevertheless, the vast majority of laboratory studies of spatial behavior and cognition in murine rodents have failed to produce evidence of sensitivity to magnetic cues. Given the central role that a magnetic compass sense plays in the spatial ecology and cognition of non-mammalian vertebrates, and the potential utility that a global/universal reference frame derived from the magnetic field would have in mammals, the question of why responses to magnetic cues have been so difficult to demonstrate reliably is of considerable importance. In this paper, we review evidence that the magnetic compass of murine rodents shares a number of properties with light-dependent compasses in a wide variety of other animals generally believed to be mediated by a radical pair mechanism (RPM) or related quantum process. Consistent with the RPM, we summarize both published and previously unpublished findings suggesting that the murine rodent compass is sensitive to low-level radio frequency (RF) fields. Finally, we argue that the presence of anthropogenic RF fields in laboratory settings, may be an important source of variability in responses of murine rodents to magnetic cues.
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