CHEMICAL CHARACTERIZATION OF THE ISOLATED CELL SURFACE OF <i>AMOEBA </i>

Allen, Herbert B.; Ault, Charles R.; Winzler, Richard J.; Danielli, J. F.

doi:10.1083/jcb.60.1.26

Cited by 36 publications

(6 citation statements)

References 26 publications

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“…However, when amoeba cells were incubated in a range of neuraminidase concentrations from 1.0 to 100 mU/ml, we did not observe any reduction in directionality and speed (results not shown) produced by an applied electric field of 150 V/m. These results confirm that amoeba cells do not have sialic acid groups in their glycocalyx as reported by Allen et al [].…”

Section: Discussionsupporting

confidence: 92%

“…In contrast, when amoeba cells were subjected to neuraminidase digestion at different concentrations (1.0-100 mU/ml) for an hour, the cells displayed the usual increase in directionality and motility of amoebae in an applied electric field. The absence of an effect of neuraminidase is consistent with the absence of sialic acids in the amoeba glycocalyx [Allen et al, 1974].…”

Section: Resultssupporting

confidence: 70%

“…Culture medium is easy to prepare and does not require sterile hoods or pipettes to passage them. Moreover, amoebae have a glycocalyx [Brewer and Bell, ; Allen et al, ; Topf and Stockem, ] and are, thus, suitable for the evaluation of the electromechanical model.…”

Section: Introductionmentioning

confidence: 99%

“…Culture medium is easy to prepare and does not require sterile hoods or pipettes to passage them. Moreover, amoebae have a glycocalyx [Brewer and Bell, 1970;Allen et al, 1974;Topf and Stockem, 1996] and are, thus, suitable for the evaluation of the electromechanical model. Galvanotaxis or electrotaxis, the migration of cells under the application of a DC electric field, serves as a convenient effect for studying mechanisms because it is a process that is readily reproduced and is easily measured in real time.…”

Section: Introductionmentioning

confidence: 99%

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Glycocalyx bending by an electric field increases cell motility

Hart

Palisano

2017

Bioelectromagnetics

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The application of physiological strength electric fields may produce a wide range of effects on cells. The mechanisms by which cells detect the presence of these fields, however, are not fully understood. Previous experiments have shown that directionality of cells in the field is governed by an electromechanical mechanism in which the field exerts a torque on the negatively charged, inner glycocalyx that is then transmitted as a force on the cytoskeleton. This mechanism is similar to that by which cells detect fluid shear forces. Several authors, however, have reported that cell directionality and motility behave differently in an electric field. We propose here a second electromechanical mechanism in which the field bends the negatively charged, outer glycocalyx in proximity to the substrate, increasing cell adhesion and, thus, cell motility. The increase in motility depends not only on the field strength, but also on the adhesion of the cell to the substrate prior to application of the field. We show that these mechanisms are common to both human cells and amoebae and, hence, are evolutionarily conserved. Furthermore, the mechanism for detection of electric fields is simply an extension of the mechanism for detecting fluid shears. Bioelectromagnetics. 38:482-493, 2017. © 2017 Wiley Periodicals, Inc.

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Section: Discussionsupporting

confidence: 92%

Section: Resultssupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Glycocalyx bending by an electric field increases cell motility

Hart

Palisano

2017

Bioelectromagnetics

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“…This suggestion is interesting in view of the high phosphate content found in the surface layers of Amoeba sp. (1), and the presence, in electron micrographs of the surface layers from which the chemical analyses were made, of numerous small dense bodies. The attachment of these bodies to the plasmalemma appears to be constant, and the bodies apparently glide beneath the plasmalemma under the influence of centrifugal forces, since they are collected at the centripetal pole of Amoeba proteus Of the functions which may be attributed to the HSBs of amoebae, the observation that HSBfree Chaos are more fragile than normal, HSBcontaining ameobae, in that they are more liable to be ruptured at an air-water interface, owing to their lower specific gravity, may be of survival significance.…”

Section: Collection Of the Hsbs By Centrifugation In Vivomentioning

confidence: 99%

Studies on the heavy spherical (refractive) bodies of freshwater Amoebae. I. Morphology and regeneration of HSBS in Chaos carolinense

Chapman-Andresen

1976

Carlsberg Res. Commun.

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*Supported by The Carlsberg FoundationThe heavy spherical bodies of Amoeba and Chaos are refractive organelles, varying in size from ca. 10 ~tm in diameter, down to the limit of resolution of the light microscope. These inclusions have many characteristics in common with the phosphate-rich, Jvolutin~ granules of other unicellular organisms, but differ from the latter in being constantly present in healthy growing amoebae, while in other organisms they appear only under conditions of nutritional imbalance. The fine structure of the HSBs of Amoeba and Chaos show that the organelles are membrane-bound, with an electron translucent periphery, and an electron dense inner core which sublimes in the electron beam, but which is stabilized by lead staining. During centrifugation in vivo, the HSBs collect at the centrifugal pole of the amoebae; under favourable conditions, a HSB-sack is formed at the heavy pole, and can be excised, leaving amoebae, normal in other respects, but containing only ca. 5% of the normal complement of HSBs. Using this method for obtaining practically HSB-free amoebae, the regeneration of HSBs was studied in Chaos carolinense, by determining the number and size distribution of HSBs in a standard volume in fixed, whole mounts by phase contrast microscopy. It was found that although the number of HSBs per standard volume in both fed and starved amoebae returned to that found in control, unoperated, Chaos by 7 days after operation, the size distribution did not return to normal until ca. 50 days after excision of the HSBs, indicating that HSBs originate from precursors in the cytoplasm. Operated amoebae showed normal feeding and locomotory behaviour, and their division rate was similar to that of control amoebae. However, HSB-free amoebae were more prone to rupture at an air-water interface, presumably owing to their lower specific gravity.

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