The pellicle as a factor in the stabilization of cellular form and integrity: Effects of externally applied enzymes on the resistance of <i>Blepharisma</i> and <i>Paramecium</i> to pressure‐induced cytolysis

Asterita, Harvey; Marsland, Douglas

doi:10.1002/jcp.1030580107

Cited by 14 publications

(4 citation statements)

References 21 publications

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“…It is therefore reasonable to assume that the plasma membrane representing the external membrane of the knob might be sticky. Stickiness of the plasma membrane has been observed in protozoa in which the pellicle was removed by digestion (1). In addition, electron micrographs have disclosed that the knob has a complicated structure (42).…”

Section: Wi-iole Mount 1)reparationsmentioning

confidence: 99%

THE FINE STRUCTURE AND FUNCTION OF THE TENTACLE IN TOKOPHRYA INFUSIONUM

Rudzinska

1965

The Journal of Cell Biology

112

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The feeding apparatus of Suctoria consists of long, thin, stiff tubes called tentacles. When a swimming prey attaches to the tip of the tentacle a number of events follow in rapid succession. The tentacle broadens, a stream of tiny granules starts to move upward at its periphery to the tip, the prey becomes immobilized and shortly thereafter the cytoplasm of the still living prey begins to flow through the center of the tentacle to the body of the predator. An electron microscope study of the tentacle in Tokophrya infusionum, a protozoan of the subclass Suctoria, has disclosed a number of structural details which help to clarify some of the mechanisms involved in this unusual way of feeding. Each tentacle is composed of two concentric tubes. The lumen of the inner tube is surrounded by 49 tubular fibrils most probably of contractile nature. In the inner tube the cytoplasm of the prey is present during feeding, and in the outer tube are small dense bodies. It was found that the dense bodies originate in the cytoplasm of Tokophrya. They have an elongate, missile-like appearance, pointed at one end, rounded at the other, and are composed of several distinct segments. At the tip of the tentacle they penetrate the plasma membrane, with their pointed ends sticking out. It is assumed that the missile-like bodies play a major role in the feeding process. Their composite structure suggests that they might contain a number of enzymes which most probably are responsible for the various events preceding the actual food intake.

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Section: Wi-iole Mount 1)reparationsmentioning

confidence: 99%

THE FINE STRUCTURE AND FUNCTION OF THE TENTACLE IN TOKOPHRYA INFUSIONUM

Rudzinska

1965

The Journal of Cell Biology

112

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“…4,000 to 8,000 psi. These cells include: various free-living amoebae (Marsland and Brown, 1936;Landau, Zimmerman, and Marsland, 1954); human fibroblasts in tissue culture (Landau, 1961); various ciliates (Auclair and Marsland, 1958;Asterita and Marsland, 1961) ; Euglena and other flagellates (Byrne and Marsland, 1965); suctorians (Kitching and Pease, 1939); heliozoa (Kitching, 1957); and egg cells in process of division (Marsland, 1956). Moreover, microtubular elements have been demonstrated in many of these cells (see p. 77 for references).…”

Section: Introductionmentioning

confidence: 99%

Studies on the Microtubules in Heliozoa

Tilney

Hiramoto

Marsland

1966

The Journal of Cell Biology

Self Cite

221

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Electron microscope preparations were made of specimens of Actinosphaerium nucleofilum fixed in glutaraldehyde before, during, and after exposure to high pressures (4,000 to 8,000 psi). A study of this material showed that, although other organelles were relatively stable, the microtubular elements of the axopodia and cytosome became unstable under pressure. Their rapid disintegration under pressure was correlated with beading and retraction of the axopodia. Moreover, after the release of pressure, microtubules reappeared as soon as, or sooner than the reextension of the axopodia. The rate of disintegration increased as the pressure was raised. At 4,000 psi, few if any tubules remained after 10 min, whereas at 6,000 and 8,000 psi the disintegration was much more rapid. Some adaptational reorganization of the microtubules and axopodia occurred while relatively low pressures were maintained. This was accompanied by an actual elongation of the axopodia in specimens maintained for 20 min at 4,000 psi, but was confined to knoblike axopodial remnants in animals kept at 6,000 psi. No regeneration of tubules or axopodia occurred at 8,000 psi. The presence of fibers and a finely fibrillar material in pressurized animals suggests that these may be derivatives of microtubular disintegration. This evidence, though purely morphological, is consistent with the hypothesis that microtubules play an important role not only in maintaining the formstability of the axopodia, but also in the active process by which the axopodia reextend themselves after retraction.

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“…Generally the cells have been described as attaining a roundish shape . Asterita and Marsland (1961) attributed this shape change in part to damage to the pellicle of the cell, and in part to alterations of the cortical gel . In view of this and the extensive studies on the effects of high pressure on macromolecular synthesis (see Zimmerman, 1969Zimmerman, , 1970, we decided to investigate the effects of high pressure on cell fine structure, particularly on cortical and ciliary microtubules .…”

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confidence: 99%