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Hanzlik, Marianne; Heunemann, C.; Holtkamp-Rötzler, Elke; Winklhofer, Michael; Petersen, N.; Fleissner, Gerta

doi:10.1023/a:1009214526685

Cited by 127 publications

(54 citation statements)

References 12 publications

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“…The structure of the magnetite-based receptors in birds is not entirely clear. Single domains (Beason & Brennon 1986) as well as superparamagnetic particles have been reported (Hanzlik et al 2000;Fleissner et al 2003), and although several hypotheses of how magnetite-based receptors may convey magnetic input have been suggested (e.g. In any case, a 0.5 nT pulse, as applied in the present study, must be expected to markedly change its output.…”

Section: Discussionmentioning

confidence: 65%

Bird navigation: what type of information does the magnetite-based receptor provide?

et al. 2006

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Previous experiments have shown that a short, strong magnetic pulse caused migratory birds to change their headings from their normal migratory direction to an easterly direction in both spring and autumn. In order to analyse the nature of this pulse effect, we subjected migratory Australian silvereyes, Zosterops lateralis, to a magnetic pulse and tested their subsequent response under different magnetic conditions. In the local geomagnetic field, the birds preferred easterly headings as before, and when the horizontal component of the magnetic field was shifted 908 anticlockwise, they altered their headings accordingly northwards. In a field with the vertical component inverted, the birds reversed their headings to westwards, indicating that their directional orientation was controlled by the normal inclination compass. These findings show that although the pulse strongly affects the magnetite particles, it leaves the functional mechanism of the magnetic compass intact. Thus, magnetite-based receptors seem to mediate magnetic 'map'-information used to determine position, and when affected by a pulse, they provide birds with false positional information that causes them to change their course.

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Section: Discussionmentioning

confidence: 65%

Bird navigation: what type of information does the magnetite-based receptor provide?

et al. 2006

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“…However, Prussian blue is not a specific stain for magnetite, and there have been instances where false-positives have led to misidentifications. For example, in the case of homing pigeons, the long-held claim that Prussian blue positive structures in the upper beak are putative magnetoreceptor cells [59,63,64] was overturned by the more recent finding that they are in fact iron-rich macrophages [19,60]. The potential for generating false-positives with the Prussian blue technique highlights the MPM composition problem (i.e.…”

Section: Finding a Magnetic Particle-mediated Magnetoreceptor Systemmentioning

confidence: 99%

“…Several studies have combined direct and indirect approaches, such as optical and electron microscopy with SQUID, in the search for an MPM system (table 4) [64,80,82,[84][85][86][87][88][89][90][91][92][93][94][95][96].…”

Section: Combined Direct and Indirect Observationsmentioning

confidence: 99%

Magnetic particle-mediated magnetoreception

Shaw

Boyd

House

et al. 2015

J. R. Soc. Interface.

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Behavioural studies underpin the weight of experimental evidence for the existence of a magnetic sense in animals. In contrast, studies aimed at understanding the mechanistic basis of magnetoreception by determining the anatomical location, structure and function of sensory cells have been inconclusive. In this review, studies attempting to demonstrate the existence of a magnetoreceptor based on the principles of the magnetite hypothesis are examined. Specific attention is given to the range of techniques, and main animal model systems that have been used in the search for magnetite particulates. Anatomical location/cell rarity and composition are identified as two key obstacles that must be addressed in order to make progress in locating and characterizing a magnetite-based magnetoreceptor cell. Avenues for further study are suggested, including the need for novel experimental, correlative, multimodal and multidisciplinary approaches. The aim of this review is to inspire new efforts towards understanding the cellular basis of magnetoreception in animals, which will in turn inform a new era of behavioural research based on first principles.

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“…It shows a very steep increase below 20 K (figure 4) due to the superposition of the ferritin ordering. The magnetization difference, M FC KM ZFC , between the FC and ZFC curves was obtained by subtraction; it was then differentiated with respect to temperature to obtain the distribution of the blocking temperature T B of the ferritin cores (figure 4, inset; Hanzlik et al 2000;Mamiya et al 2005).…”

Section: Isothermal Remanent Magnetizationmentioning

confidence: 99%

Magnetic iron compounds in the human brain: a comparison of tumour and hippocampal tissue

Brem

Hirt²,

Winklhofer³

et al. 2006

J. R. Soc. Interface.

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Iron is a central element in the metabolism of normal and malignant cells. Abnormalities in iron and ferritin expression have been observed in many types of cancer. Interest in characterizing iron compounds in the human brain has increased due to advances in determining a relationship between excess iron accumulation and neurological and neurodegenerative diseases. In this work, four different magnetic methods have been employed to characterize the iron phases and magnetic properties of brain tumour (meningiomas) tissues and non-tumour hippocampal tissues. Four main magnetic components can be distinguished: the diamagnetic matrix, nearly paramagnetic blood, antiferromagnetic ferrihydrite cores of ferritin and ferrimagnetic magnetite and/or maghemite. For the first time, open hysteresis loops have been observed on human brain tissue at room temperature. The hysteresis properties indicate the presence of magnetite and/or maghemite particles that exhibit stable single-domain (SD) behaviour at room temperature. A significantly higher concentration of magnetically ordered magnetite and/or maghemite and a higher estimated concentration of heme iron was found in the meningioma samples. First-order reversal curve diagrams on meningioma tissue further show that the stable SD particles are magnetostatically interacting, implying high-local concentrations (clustering) of these particles in brain tumours. These findings suggest that brain tumour tissue contains an elevated amount of remanent iron oxide phases.

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Cited by 127 publications

References 12 publications

Bird navigation: what type of information does the magnetite-based receptor provide?

Bird navigation: what type of information does the magnetite-based receptor provide?

Magnetic particle-mediated magnetoreception

Magnetic iron compounds in the human brain: a comparison of tumour and hippocampal tissue

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