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Magnetoreception system in honeybees (Apis mellifera).

Hsu CY, Ko FY, Li CW, Fann K, Lue JT - PLoS ONE (2007)

Bottom Line: A concomitant release of calcium ion was observed by confocal microscope.The associated cytoskeleton may thus relay the magnetosignal, initiating a neural response.A model for the mechanism of magnetoreception in honeybees is proposed, which may be applicable to most, if not all, magnetotactic organisms.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Science, Chang Gung University, Tao-Yuan, Taiwan. hsu@mail.cgu.edu.tw

ABSTRACT
Honeybees (Apis mellifera) undergo iron biomineralization, providing the basis for magnetoreception. We showed earlier the presence of superparamagnetic magnetite in iron granules formed in honeybees, and subscribed to the notion that external magnetic fields may cause expansion or contraction of the superparamagnetic particles in an orientation-specific manner, relaying the signal via cytoskeleton (Hsu and Li 1994). In this study, we established a size-density purification procedure, with which quantitative amount of iron granules was obtained from honey bee trophocytes and characterized; the density of iron granules was determined to be 1.25 g/cm(3). While we confirmed the presence of superparamagnetic magnetite in the iron granules, we observed changes in the size of the magnetic granules in the trophycytes upon applying additional magnetic field to the cells. A concomitant release of calcium ion was observed by confocal microscope. This size fluctuation triggered the increase of intracellular Ca(+2) , which was inhibited by colchicines and latrunculin B, known to be blockers for microtubule and microfilament syntheses, respectively. The associated cytoskeleton may thus relay the magnetosignal, initiating a neural response. A model for the mechanism of magnetoreception in honeybees is proposed, which may be applicable to most, if not all, magnetotactic organisms.

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The magnetic map hypothesis of magnetoreception for orientation and positioning during foraging and homing. (A) When honeybees fly in the direction paralleled to external magnetic field, MG expands due to the repellent force of SM. When honeybees fly in the perpendicular direction to external magnetic field, MG contracts in the same direction due to the attractive force of SM. (B) The direction of magnetic field of SM is parallel to the direction of Earth's magnetic field at flower 1. SM would be in a side-by-side position, creating repulsion and subsequent expansion of the MGs. At the flower 3, the direction of magnetic field of SM is vertical to the direction of Earth's magnetic field. SM would be positioned end-to-end, creating attraction and subsequent contraction of the MGs. This contraction induces the tensing of cytoskeletons and triggers the increase of [Ca+2]i in trophocytes. At flower 2, the relaxing and tensing of cytoskeletons is a mixture of flower 1 and flower 3. The direction of magnetic field of SM at the flower 1 is the same as flower 5. Flower 2 is the same as flower 6, and so on. The distinction in both cases is dependent on the direction of waggle dance.
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pone-0000395-g007: The magnetic map hypothesis of magnetoreception for orientation and positioning during foraging and homing. (A) When honeybees fly in the direction paralleled to external magnetic field, MG expands due to the repellent force of SM. When honeybees fly in the perpendicular direction to external magnetic field, MG contracts in the same direction due to the attractive force of SM. (B) The direction of magnetic field of SM is parallel to the direction of Earth's magnetic field at flower 1. SM would be in a side-by-side position, creating repulsion and subsequent expansion of the MGs. At the flower 3, the direction of magnetic field of SM is vertical to the direction of Earth's magnetic field. SM would be positioned end-to-end, creating attraction and subsequent contraction of the MGs. This contraction induces the tensing of cytoskeletons and triggers the increase of [Ca+2]i in trophocytes. At flower 2, the relaxing and tensing of cytoskeletons is a mixture of flower 1 and flower 3. The direction of magnetic field of SM at the flower 1 is the same as flower 5. Flower 2 is the same as flower 6, and so on. The distinction in both cases is dependent on the direction of waggle dance.

Mentions: Based on the results of cellular studies, we postulate a magnetic map hypothesis for the magnetoreception as follows: the magnetic field induces the size of MGs to shrink at the paralleled direction to the magnetic field and to enlarge at the vertical direction in the horizontal plane (Figure 7A). This fluctuation in the size of MGs can induce the relaxing and tensing of cytoskeletons to trigger the increase of [Ca+2]i. The increase of [Ca+2]i can further trigger signal transduction for magnetoreception. This is probably the mechanism by which honeybees establish the magnetic map in memory during orientation flights. Thus, foragers can set course at any direction to forage and to home from any location (Figure 7B). This magnetoreception system is highly sensitive, because honeybees can detect magnetic field as low as 26 nT, compared to the 45000 nT of Earth's magnetic field [22]. In addition, each bee has about 1.87×1011 SM (2.2×108 IGs per bee, 8.5×103 SM per IG and SM occurs in 10% of IGs) [13].


Magnetoreception system in honeybees (Apis mellifera).

Hsu CY, Ko FY, Li CW, Fann K, Lue JT - PLoS ONE (2007)

The magnetic map hypothesis of magnetoreception for orientation and positioning during foraging and homing. (A) When honeybees fly in the direction paralleled to external magnetic field, MG expands due to the repellent force of SM. When honeybees fly in the perpendicular direction to external magnetic field, MG contracts in the same direction due to the attractive force of SM. (B) The direction of magnetic field of SM is parallel to the direction of Earth's magnetic field at flower 1. SM would be in a side-by-side position, creating repulsion and subsequent expansion of the MGs. At the flower 3, the direction of magnetic field of SM is vertical to the direction of Earth's magnetic field. SM would be positioned end-to-end, creating attraction and subsequent contraction of the MGs. This contraction induces the tensing of cytoskeletons and triggers the increase of [Ca+2]i in trophocytes. At flower 2, the relaxing and tensing of cytoskeletons is a mixture of flower 1 and flower 3. The direction of magnetic field of SM at the flower 1 is the same as flower 5. Flower 2 is the same as flower 6, and so on. The distinction in both cases is dependent on the direction of waggle dance.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC1851986&req=5

pone-0000395-g007: The magnetic map hypothesis of magnetoreception for orientation and positioning during foraging and homing. (A) When honeybees fly in the direction paralleled to external magnetic field, MG expands due to the repellent force of SM. When honeybees fly in the perpendicular direction to external magnetic field, MG contracts in the same direction due to the attractive force of SM. (B) The direction of magnetic field of SM is parallel to the direction of Earth's magnetic field at flower 1. SM would be in a side-by-side position, creating repulsion and subsequent expansion of the MGs. At the flower 3, the direction of magnetic field of SM is vertical to the direction of Earth's magnetic field. SM would be positioned end-to-end, creating attraction and subsequent contraction of the MGs. This contraction induces the tensing of cytoskeletons and triggers the increase of [Ca+2]i in trophocytes. At flower 2, the relaxing and tensing of cytoskeletons is a mixture of flower 1 and flower 3. The direction of magnetic field of SM at the flower 1 is the same as flower 5. Flower 2 is the same as flower 6, and so on. The distinction in both cases is dependent on the direction of waggle dance.
Mentions: Based on the results of cellular studies, we postulate a magnetic map hypothesis for the magnetoreception as follows: the magnetic field induces the size of MGs to shrink at the paralleled direction to the magnetic field and to enlarge at the vertical direction in the horizontal plane (Figure 7A). This fluctuation in the size of MGs can induce the relaxing and tensing of cytoskeletons to trigger the increase of [Ca+2]i. The increase of [Ca+2]i can further trigger signal transduction for magnetoreception. This is probably the mechanism by which honeybees establish the magnetic map in memory during orientation flights. Thus, foragers can set course at any direction to forage and to home from any location (Figure 7B). This magnetoreception system is highly sensitive, because honeybees can detect magnetic field as low as 26 nT, compared to the 45000 nT of Earth's magnetic field [22]. In addition, each bee has about 1.87×1011 SM (2.2×108 IGs per bee, 8.5×103 SM per IG and SM occurs in 10% of IGs) [13].

Bottom Line: A concomitant release of calcium ion was observed by confocal microscope.The associated cytoskeleton may thus relay the magnetosignal, initiating a neural response.A model for the mechanism of magnetoreception in honeybees is proposed, which may be applicable to most, if not all, magnetotactic organisms.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Science, Chang Gung University, Tao-Yuan, Taiwan. hsu@mail.cgu.edu.tw

ABSTRACT
Honeybees (Apis mellifera) undergo iron biomineralization, providing the basis for magnetoreception. We showed earlier the presence of superparamagnetic magnetite in iron granules formed in honeybees, and subscribed to the notion that external magnetic fields may cause expansion or contraction of the superparamagnetic particles in an orientation-specific manner, relaying the signal via cytoskeleton (Hsu and Li 1994). In this study, we established a size-density purification procedure, with which quantitative amount of iron granules was obtained from honey bee trophocytes and characterized; the density of iron granules was determined to be 1.25 g/cm(3). While we confirmed the presence of superparamagnetic magnetite in the iron granules, we observed changes in the size of the magnetic granules in the trophycytes upon applying additional magnetic field to the cells. A concomitant release of calcium ion was observed by confocal microscope. This size fluctuation triggered the increase of intracellular Ca(+2) , which was inhibited by colchicines and latrunculin B, known to be blockers for microtubule and microfilament syntheses, respectively. The associated cytoskeleton may thus relay the magnetosignal, initiating a neural response. A model for the mechanism of magnetoreception in honeybees is proposed, which may be applicable to most, if not all, magnetotactic organisms.

Show MeSH
Related in: MedlinePlus