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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 images of MGs in the trophocytes obtained by confocal microscope. (A) MGs (arrowhead) appear as tiny black particles under low magnification in the live trophocytes. Arrow indicates oil body. Scale bar, 8 µm. (B) MGs (arrowhead) appear as black granules under high magnification in the live trophocytes. The images of MGs are obtained without the application of 1 Gauss magnetic field. Arrow indicates oil body. Inset shows a magnified MG. Scale bar, 1 µm. (C) The same images obtained by the application of 1 Gauss magnetic field in the live trophocytes. White arrow indicates the direction of magnetic field. Arrowhead indicates MGs. Arrow indicates oil body. Inset shows a magnified MG. Scale bar, 1 µm. (D) MGs (arrowhead) appear as tiny black particles under low magnification in the dead trophocytes. Scale bar, 8 µm. (E) MGs (arrowhead) appear as black granules under high magnification in the dead trophocytes. The images of MGs are obtained without the application of 1 Gauss magnetic field. Inset shows a magnified MG. Scale bar, 1 µm. (F) The same images obtained by the application of 1 Gauss magnetic field in the dead trophocytes. Arrowhead indicates MGs. White arrow indicates the direction of magnetic field. Inset shows a magnified MG. Scale bar, 1 µm.
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pone-0000395-g004: The images of MGs in the trophocytes obtained by confocal microscope. (A) MGs (arrowhead) appear as tiny black particles under low magnification in the live trophocytes. Arrow indicates oil body. Scale bar, 8 µm. (B) MGs (arrowhead) appear as black granules under high magnification in the live trophocytes. The images of MGs are obtained without the application of 1 Gauss magnetic field. Arrow indicates oil body. Inset shows a magnified MG. Scale bar, 1 µm. (C) The same images obtained by the application of 1 Gauss magnetic field in the live trophocytes. White arrow indicates the direction of magnetic field. Arrowhead indicates MGs. Arrow indicates oil body. Inset shows a magnified MG. Scale bar, 1 µm. (D) MGs (arrowhead) appear as tiny black particles under low magnification in the dead trophocytes. Scale bar, 8 µm. (E) MGs (arrowhead) appear as black granules under high magnification in the dead trophocytes. The images of MGs are obtained without the application of 1 Gauss magnetic field. Inset shows a magnified MG. Scale bar, 1 µm. (F) The same images obtained by the application of 1 Gauss magnetic field in the dead trophocytes. Arrowhead indicates MGs. White arrow indicates the direction of magnetic field. Inset shows a magnified MG. Scale bar, 1 µm.

Mentions: To study the role of MGs as magnetoreceptors, we examined under confocal microscope size fluctuation of MGs in trophocytea when additional magnetic field (1 Gauss) was applied. At low magnification, MGs appear as tiny black particles in both live (Figure 4A) and dead trophocytes (Figure 4D). At high magnification, MGs appear as black granules, in live (Figure 4B) and dead trophocytes (Figure 4E). After applying 1 Gauss magnetic field for 2 min, MGs in live trophocytes shrank 12±1.7% (N = 20) at the paralleled direction to magnetic field and enlarged 1.2±0.5% (N = 20) at the vertical direction in the horizontal plane (Figure 4C). In dead trophocytes, they reduced 13±1.4% (N = 20) in size at the paralleled direction to magnetic field and enlarged 4.4±0.9% (N = 20) at the vertical direction in the horizontal plane (Figure 4F). The results show that additional magnetic field can induce the size changes in MGs, owing to MGs' magnetoreceptor property.


Magnetoreception system in honeybees (Apis mellifera).

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

The images of MGs in the trophocytes obtained by confocal microscope. (A) MGs (arrowhead) appear as tiny black particles under low magnification in the live trophocytes. Arrow indicates oil body. Scale bar, 8 µm. (B) MGs (arrowhead) appear as black granules under high magnification in the live trophocytes. The images of MGs are obtained without the application of 1 Gauss magnetic field. Arrow indicates oil body. Inset shows a magnified MG. Scale bar, 1 µm. (C) The same images obtained by the application of 1 Gauss magnetic field in the live trophocytes. White arrow indicates the direction of magnetic field. Arrowhead indicates MGs. Arrow indicates oil body. Inset shows a magnified MG. Scale bar, 1 µm. (D) MGs (arrowhead) appear as tiny black particles under low magnification in the dead trophocytes. Scale bar, 8 µm. (E) MGs (arrowhead) appear as black granules under high magnification in the dead trophocytes. The images of MGs are obtained without the application of 1 Gauss magnetic field. Inset shows a magnified MG. Scale bar, 1 µm. (F) The same images obtained by the application of 1 Gauss magnetic field in the dead trophocytes. Arrowhead indicates MGs. White arrow indicates the direction of magnetic field. Inset shows a magnified MG. Scale bar, 1 µm.
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Related In: Results  -  Collection

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pone-0000395-g004: The images of MGs in the trophocytes obtained by confocal microscope. (A) MGs (arrowhead) appear as tiny black particles under low magnification in the live trophocytes. Arrow indicates oil body. Scale bar, 8 µm. (B) MGs (arrowhead) appear as black granules under high magnification in the live trophocytes. The images of MGs are obtained without the application of 1 Gauss magnetic field. Arrow indicates oil body. Inset shows a magnified MG. Scale bar, 1 µm. (C) The same images obtained by the application of 1 Gauss magnetic field in the live trophocytes. White arrow indicates the direction of magnetic field. Arrowhead indicates MGs. Arrow indicates oil body. Inset shows a magnified MG. Scale bar, 1 µm. (D) MGs (arrowhead) appear as tiny black particles under low magnification in the dead trophocytes. Scale bar, 8 µm. (E) MGs (arrowhead) appear as black granules under high magnification in the dead trophocytes. The images of MGs are obtained without the application of 1 Gauss magnetic field. Inset shows a magnified MG. Scale bar, 1 µm. (F) The same images obtained by the application of 1 Gauss magnetic field in the dead trophocytes. Arrowhead indicates MGs. White arrow indicates the direction of magnetic field. Inset shows a magnified MG. Scale bar, 1 µm.
Mentions: To study the role of MGs as magnetoreceptors, we examined under confocal microscope size fluctuation of MGs in trophocytea when additional magnetic field (1 Gauss) was applied. At low magnification, MGs appear as tiny black particles in both live (Figure 4A) and dead trophocytes (Figure 4D). At high magnification, MGs appear as black granules, in live (Figure 4B) and dead trophocytes (Figure 4E). After applying 1 Gauss magnetic field for 2 min, MGs in live trophocytes shrank 12±1.7% (N = 20) at the paralleled direction to magnetic field and enlarged 1.2±0.5% (N = 20) at the vertical direction in the horizontal plane (Figure 4C). In dead trophocytes, they reduced 13±1.4% (N = 20) in size at the paralleled direction to magnetic field and enlarged 4.4±0.9% (N = 20) at the vertical direction in the horizontal plane (Figure 4F). The results show that additional magnetic field can induce the size changes in MGs, owing to MGs' magnetoreceptor property.

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