Endocytic Processes

Chapman-Andresen, C

doi:10.1016/b978-0-12-384850-5.50016-6

Cited by 27 publications

(9 citation statements)

References 69 publications

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“…Pinocytosis is induced and locomotion is inhibited in Amoeba proteus by nonspecific electrolyte changes and by surface charge changes (Chapman-Andresen, 1962) in a manner which Gingell (1971) has suggested may reflect an influence of surface potential on pinocytosis and locomotion. These latter functions also involve transmembrane ion fluxes and changes in membrane potential (Gingell, 1971;Bingley, 1966).…”

Section: Discussionmentioning

confidence: 97%

Intrinsic electric fields and membrane bending

1984

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Section: Discussionmentioning

confidence: 97%

Intrinsic electric fields and membrane bending

1984

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“…Functions which have been suggested or demonstrated for the glycocalyx of amoebae include the control of ion passage, responses leading to endocytotic and pseudopodial activity, adhesion to a substratum or to food particles, and the passage of signals to the cytoplasm Bovee 8c Jahn, 1973;Chapman-Andresen, 1973;Hausmann, 1975a).…”

Section: Functional Sign6cance Surface Layersmentioning

confidence: 99%

Cell surface structure as a taxonomic character in the Thecamoebidae (Protozoa: Gymnamoebia)

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Blakey

1979

Zoological Journal of the Linnean Society

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Amoebae of the genera Thecarnoeba, PlaQamoeba, and Vannella, family Thecamoebidae, have a surface layer which in one or more species of each genus has been found cytochemically to be a glycocalyx or mucoid coating. In six species of Thecamoeba, this is a compact coat, sometimes with a less dense outer region, 16-73 nrn thick according to species. T. proteoides, in other respects intermediate between Thecamoeba and Amoeba, has a filamentous layer up to 78 nm thick, somewhat like those of Amoeba arid Chaos. T. granlfra has a coating or tegument more than 0.5 pm thick, differing structurally and cytochemically from the glycocalyces of the other species, and is the type-species of a new genus Denamoeba. All six species of Platyamoeba investigated, freshwater and marine, had similar glycocalyces, consisting o f a thin, dense inner layer and a thicker, lighter, outer layer. Two species of Vannella from North America bear complex structures here called glycostyles, corresponding in structure and size to those of V. simplex from Germany. There is an essential similarity between most species of Thecamoeba and the related Sappinia. Surface structure distinguishes clearly between Platyamoeba and Vannella hut does not support fragmentation of the genus Platyamoeba. Although surface structure is of considerable taxonomic value at the generic level in the Thecamoebidae and may assist in confirming identification of some Thecarnoeba species, it is less promising for differentiation ofspecies within Playamoeba and Vannella.

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“…It is regrettable that our knowledge of food uptake at levels different from those of the phagocytic vesicles in T. pyriformis is so scanty, when compared to our knowledge of pinocytosis in the large amoebae. Here extensive and fruitful studies have revealed the importance of adsorption of charged molecules, the existence of inducers of pinocytosis, and the timing and the extent of the uptake of both high-and low-molecular weight compounds: for reviews see HOLTER (44,45,46) and CHAP-MAN-ANDRESEN (7,8,9) (105)). The outer membrane, the plasma membrane, covers the entire surface of the cell, also the cilia; immediately beneath the plasma membrane is a mosaic of flat, membrane-bounded ~alveoli,,; cilia and mucocysts emerge from the underlying ectoplasm between adjacent alveoli (PITELKA (75)).…”

Section: Pinocytic Vacuoles and Vesiclesmentioning

confidence: 99%

Nutrient uptake in Tetrahymena pyriformis

Rasmussen

1976

Carlsberg Res. Commun.

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Several morphological structures have been implicated in nutrient uptake in the ciliate protozoon, Tetrahymena pyriformis: food vacuoles, various types of vesicles and the plasma membrane. It is the object of this report to discuss the roles of these organelles in food uptake. Measurements of multiplication rates under conditions where food vacuole formation could be controlled experimentally suggested that the food vacuoles (about 5 rtm in diameter) were essential for rapid cell multiplication in various standard growth media. If, however, concentrations of certain specific nutrients (different for different strains of T. pyriformis) were high, then the cells could multiply rapidly even when food vacuoles were absent. Furthermore, multiplication rates of cells supplied with particulate or dissolved egg albumin as the amino acid source, suggested that the food vacuoles took up particulate egg albumin well, but dissolved egg albumin poorly. The role in food uptake of vesicles with a diameter of less than 1 vm remains largely unknown. Our present knowledge of them is not yet sufficiently detailed to permit estimations of the rates with which they are formed or of their total number per cell. The plasma membrane has carrier-mediated uptake sites for a number of nutrients such as amino acids and nucleosides. It is likely that this type of uptake mechanism plays a quantitatively important role in T. pyriformis whenever such compounds are present in the extracellular fluid.

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Endocytic Processes

Cited by 27 publications

References 69 publications

Intrinsic electric fields and membrane bending

Intrinsic electric fields and membrane bending

Cell surface structure as a taxonomic character in the Thecamoebidae (Protozoa: Gymnamoebia)

Nutrient uptake in Tetrahymena pyriformis

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