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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 properties of IGs determined by magnetic-determining techniques. (A) An averaged magnetization curve of SQUID from the purified IGs at 300°K for six runs. (B) An image of AFM from one of the purified IGs. (C) An image of MFM from one of the purified IGs. (D) A spectrum of ESCA from the purified IGs. The left thin line shows the Fe(2p1/2) of FeOOH. The middle thin line shows the Fe(2p3/2) of Fe2O3. The right thin line shows the Fe(2p1/2) of FeO. (E) A photoelectron spectrum of elemental composition of ESCA from the purified IGs. (F) Typical X-band resonance spectra from the purified IGs at different temperatures. Right inset shows a magnified image from the arrow. Left inset shows a magnified image from the arrowhead.
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pone-0000395-g003: The magnetic properties of IGs determined by magnetic-determining techniques. (A) An averaged magnetization curve of SQUID from the purified IGs at 300°K for six runs. (B) An image of AFM from one of the purified IGs. (C) An image of MFM from one of the purified IGs. (D) A spectrum of ESCA from the purified IGs. The left thin line shows the Fe(2p1/2) of FeOOH. The middle thin line shows the Fe(2p3/2) of Fe2O3. The right thin line shows the Fe(2p1/2) of FeO. (E) A photoelectron spectrum of elemental composition of ESCA from the purified IGs. (F) Typical X-band resonance spectra from the purified IGs at different temperatures. Right inset shows a magnified image from the arrow. Left inset shows a magnified image from the arrowhead.

Mentions: By the use of SQUID magnetometers, an averaged SQUID magnetization curve showed that IGs possess a residual magnetization of 2.5×10−5 emu, a saturation magnetization of 2.83×10−4 emu, and an intrinsic coercivity of 100–150 Gauss (Figure 3A). Hence, these IGs are magnetically soft. The soft-hysteresis loops reflect the easy axis of magnetization, which is in-plane on the surface, plausibly as a result of the magnetite granules being formed in the trophocytes. The smallness of coercivity confirms that the magnetite exists in a superparamagnetic state.


Magnetoreception system in honeybees (Apis mellifera).

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

The magnetic properties of IGs determined by magnetic-determining techniques. (A) An averaged magnetization curve of SQUID from the purified IGs at 300°K for six runs. (B) An image of AFM from one of the purified IGs. (C) An image of MFM from one of the purified IGs. (D) A spectrum of ESCA from the purified IGs. The left thin line shows the Fe(2p1/2) of FeOOH. The middle thin line shows the Fe(2p3/2) of Fe2O3. The right thin line shows the Fe(2p1/2) of FeO. (E) A photoelectron spectrum of elemental composition of ESCA from the purified IGs. (F) Typical X-band resonance spectra from the purified IGs at different temperatures. Right inset shows a magnified image from the arrow. Left inset shows a magnified image from the arrowhead.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0000395-g003: The magnetic properties of IGs determined by magnetic-determining techniques. (A) An averaged magnetization curve of SQUID from the purified IGs at 300°K for six runs. (B) An image of AFM from one of the purified IGs. (C) An image of MFM from one of the purified IGs. (D) A spectrum of ESCA from the purified IGs. The left thin line shows the Fe(2p1/2) of FeOOH. The middle thin line shows the Fe(2p3/2) of Fe2O3. The right thin line shows the Fe(2p1/2) of FeO. (E) A photoelectron spectrum of elemental composition of ESCA from the purified IGs. (F) Typical X-band resonance spectra from the purified IGs at different temperatures. Right inset shows a magnified image from the arrow. Left inset shows a magnified image from the arrowhead.
Mentions: By the use of SQUID magnetometers, an averaged SQUID magnetization curve showed that IGs possess a residual magnetization of 2.5×10−5 emu, a saturation magnetization of 2.83×10−4 emu, and an intrinsic coercivity of 100–150 Gauss (Figure 3A). Hence, these IGs are magnetically soft. The soft-hysteresis loops reflect the easy axis of magnetization, which is in-plane on the surface, plausibly as a result of the magnetite granules being formed in the trophocytes. The smallness of coercivity confirms that the magnetite exists in a superparamagnetic state.

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