Limits...
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.

Show MeSH

Related in: MedlinePlus

IGs purified from the trophocytes of honeybees. (A) A large amount of IGs appear in precipitates purified from the trophocytes. Scale bar, 1 µm. (B) Purified IGs enclosed with lipid-bilayer membranes (arrowhead). Scale bar, 100 nm. (C) EDX spectrum is obtained from an IG in the purified precipitates. Iron (Fe), calcium (Ca) and phosphorus (P) are present in an IG. STEM mode of 100-kV accelerating voltage was used; counts were made for 100 seconds. (D) EDX spectrum of spurr's resin is devoid of IGs in the purified precipitates. The experimental conditions are the same as in C. (E) Size distribution of purified IGs calculated from the TEM pictures (N = 274). N, total number of granules used in this calculation.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC1851986&req=5

pone-0000395-g002: IGs purified from the trophocytes of honeybees. (A) A large amount of IGs appear in precipitates purified from the trophocytes. Scale bar, 1 µm. (B) Purified IGs enclosed with lipid-bilayer membranes (arrowhead). Scale bar, 100 nm. (C) EDX spectrum is obtained from an IG in the purified precipitates. Iron (Fe), calcium (Ca) and phosphorus (P) are present in an IG. STEM mode of 100-kV accelerating voltage was used; counts were made for 100 seconds. (D) EDX spectrum of spurr's resin is devoid of IGs in the purified precipitates. The experimental conditions are the same as in C. (E) Size distribution of purified IGs calculated from the TEM pictures (N = 274). N, total number of granules used in this calculation.

Mentions: In this study, we established a size-density procedure new for purification of IGs from trophocytes (Figure 1). Numerous electron-dense granules were observed in the purified precipitates by transmission electron microscope (TEM) (Figure 2A). The morphology of these granules is similar to that of IGs in the trophocytes, but only a few retained their vesicle membrane (Figure 2B). With energy dispersive X-ray spectrum microanalyzer under scanning transmission electron microscope (STEM), these electron-dense granules is shown to contain a higher concentration of iron, phosphorus and a lower concentration of calcium as compared to spurr's resin, a control. Other elements were noted, with copper (Cu) derived from the support grid and lead (Pb) and uranium (U) from TEM stain solution (Figure 2C and 2D). The size of these electron-dense granules ranged from 0.1 µm to 0.6 µm in diameter, with an average of 0.3±0.1 µm (N = 274) (Figure 2E). Energy dispersive X-ray spectrum of individual granule is consistent with that of IGs in the trophocytes of honeybees previously reported [24]–[26].


Magnetoreception system in honeybees (Apis mellifera).

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

IGs purified from the trophocytes of honeybees. (A) A large amount of IGs appear in precipitates purified from the trophocytes. Scale bar, 1 µm. (B) Purified IGs enclosed with lipid-bilayer membranes (arrowhead). Scale bar, 100 nm. (C) EDX spectrum is obtained from an IG in the purified precipitates. Iron (Fe), calcium (Ca) and phosphorus (P) are present in an IG. STEM mode of 100-kV accelerating voltage was used; counts were made for 100 seconds. (D) EDX spectrum of spurr's resin is devoid of IGs in the purified precipitates. The experimental conditions are the same as in C. (E) Size distribution of purified IGs calculated from the TEM pictures (N = 274). N, total number of granules used in this calculation.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0000395-g002: IGs purified from the trophocytes of honeybees. (A) A large amount of IGs appear in precipitates purified from the trophocytes. Scale bar, 1 µm. (B) Purified IGs enclosed with lipid-bilayer membranes (arrowhead). Scale bar, 100 nm. (C) EDX spectrum is obtained from an IG in the purified precipitates. Iron (Fe), calcium (Ca) and phosphorus (P) are present in an IG. STEM mode of 100-kV accelerating voltage was used; counts were made for 100 seconds. (D) EDX spectrum of spurr's resin is devoid of IGs in the purified precipitates. The experimental conditions are the same as in C. (E) Size distribution of purified IGs calculated from the TEM pictures (N = 274). N, total number of granules used in this calculation.
Mentions: In this study, we established a size-density procedure new for purification of IGs from trophocytes (Figure 1). Numerous electron-dense granules were observed in the purified precipitates by transmission electron microscope (TEM) (Figure 2A). The morphology of these granules is similar to that of IGs in the trophocytes, but only a few retained their vesicle membrane (Figure 2B). With energy dispersive X-ray spectrum microanalyzer under scanning transmission electron microscope (STEM), these electron-dense granules is shown to contain a higher concentration of iron, phosphorus and a lower concentration of calcium as compared to spurr's resin, a control. Other elements were noted, with copper (Cu) derived from the support grid and lead (Pb) and uranium (U) from TEM stain solution (Figure 2C and 2D). The size of these electron-dense granules ranged from 0.1 µm to 0.6 µm in diameter, with an average of 0.3±0.1 µm (N = 274) (Figure 2E). Energy dispersive X-ray spectrum of individual granule is consistent with that of IGs in the trophocytes of honeybees previously reported [24]–[26].

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