Comparative freeze-fracture study of perialgal and digestive vacuoles in Paramecium bursaria

1984 ◽  
Vol 71 (1) ◽  
pp. 121-140
Author(s):  
R. Meier ◽  
M. Lefort-Tran ◽  
M. Pouphile ◽  
W. Reisser ◽  
W. Wiessner
Keyword(s):  
Algal Cell ◽  
Freeze Fracture ◽  
Paramecium Bursaria ◽  
Digestive Vacuole ◽  
Intimate Contact ◽  
Chlorella Sp ◽  
Membrane Topography ◽  
Long Time ◽  
Membrane Changes ◽  
Endocytic Activity

In the endosymbiotic unit of Paramecium bursaria (Ciliata) and Chlorella sp. (Chlorophyceae) algae are enclosed individually in perialgal vacuoles, which do not show acid phosphatase activity and thus differ from digestive vacuoles. Both types of vacuoles have been studied by freeze-fracture. Perialgal vacuoles are nearly spherical; their membrane always fits tightly to the algal surface. The vacuole size and shape do not vary much. During division of the algal cell into four autospores the vacuole diameter only doubles. After autospore formation the vacuole invaginates around the algal daughter cells and divides. Newly formed perialgal vacuoles remain in intimate contact and exhibit characteristic attachment zones before final separation. The two fracture faces of perialgal vacuole membranes are homogeneously covered with intramembranous particles (IMPs) but rarely show signs of vesicles pinching off or fusing with the membrane, except during vacuole division. The P-faces bear more IMPs (3164 +/− 625 IMP/micron 2) than the E-faces (654 +/− 208 IMP/micron 2). The range of IMP density on both faces is enormous, suggesting that the membrane is not static. Membrane changes are supposed to occur simultaneously with the enlargement of the vacuole and to be caused by fusion with cytoplasmic vesicles, as the fractured necks on vacuole membranes may indicate. Digestive vacuoles in P. bursaria show significant variations in size, shape, membrane topography and IMP density, as well as signs of endocytic activity. Different vacuole populations are present in P. bursaria according to different feeding conditions: ciliates fed for a long time have small vacuoles with few IMPs (322 +/− 198 IMP/micron 2 on the E-faces, 1438 +/− 458 IMP/micron 2 on the P-faces), which are probably condensed digestive vacuoles, whereas organisms fed for a short time have larger vacuoles with highly particulate faces (680 +/− 282 IMP/micron 2 on the E-faces, 2701 +/− 503 IMP/micron 2 on the P-faces) and thus are supposed to be older vacuoles. The digestive vacuole membrane changes continuously. Compared to digestive vacuoles perialgal vacuoles are characterized by small size combined with high IMP density on the two fracture faces. Their IMP densities resemble those of old digestive vacuole membranes. However, it would be premature to conclude that membranes of perialgal and old digestive vacuoles are identical. Membranes of old digestive vacuoles are mainly derived from lysosomal material, which presumably does not contribute to the formation of perialgal vacuole membranes as is indicated by the small vacuole diameter; fusion with lysosomes would considerably enlarge it.(ABSTRACT TRUNCATED AT 400 WORDS)

Freeze-Fracture Evidence of Differences between Membranes of Perialgal and Digestive Vacuoles in Paramecium bursaria

1980 ◽  
Vol 35 (11-12) ◽  
pp. 1107-1110 ◽  
Author(s):  
Renate Meier ◽  
Werner Reisser ◽  
Wolfgang Wiessner ◽  
Marcelle Lefort-Tran
Keyword(s):  
Life Cycle ◽  
Freeze Fracture ◽  
Paramecium Bursaria ◽  
Digestive Vacuole ◽  
The Stability

Abstract Measurements of particle densities on the two freeze-fracture faces of digestive and perialgal vacuole membranes in green and aposym biotic Paramecium bursaria Ehrbg. show distinct differences between the P-faces of both membrane types. The distribution of particle densities is more homogenous on the P-faces of perialgal vacuole membranes than on the P-faces of digestive vacuole membranes. Possibly homogeneity among peri­ algal vacuole membranes reflects the stability of perialgal vacuoles during their life cycle. Perhaps lysosomes cannot fuse with them.

Infection of algae-free Paramecium bursaria with symbiotic Chlorella sp. isolated from green paramecia

1989 ◽  
Vol 93 (3) ◽  
pp. 571-579
Author(s):  
RENATE MEIER ◽  
WOLFGANG WIESSNER
Keyword(s):  
Algal Cell ◽  
Middle Part ◽  
Paramecium Bursaria ◽  
Middle Region ◽  
Free Medium ◽  
Large Vacuole ◽  
Chlorella Sp ◽  
The Moment ◽  
In Cells

Algae-free Paramecium bursaria was exposed to cells of Chlorella sp. for 30s (pulse) and then incubated in algae-free medium for periods between 0 and 15 min. During this chase the fate of the vacuoles formed during the exposure to algae was followed in order to reveal the moment of perialgal vacuole (PV) formation. PVs are characterized by always enclosing an individual algal cell and thus differ from digestive vacuoles (DVs). PVs did not appear immediately after the pulse, but were found only in cells chased for at least 3 min. In those ciliates the algae-containing vacuoles were more than 3 min old and located in the middle part of the cell. These results showed that PVs were not formed directly at the cytopharynx, but many algae were at first enclosed together in large DVs. After the release from the cytopharynx DVs undergo a sequence of fusion events during their cyclosis: fusion with acidosomes apparently occurs at the cell's posterior end, not later than 2 min, and fusion with lysosomes in the middle region of the cell at the earliest at about 7 min, after the pinching off of a DV from the cytopharynx. Thus, PVs appeared to develop from condensing DVs after acidosomal but before lysosomal fusion. As the first step, part of the DV enclosing an individual algal cell must detach from the large vacuole. Further steps and the implications of the mechanism of PV formation resulting in the re-establishment of endosymbionts in P. bursaria are discussed.

Membrane changes associated with mucus production by intestinal goblet cells

1978 ◽  
Vol 33 (1) ◽  
pp. 301-316
Author(s):  
J.G. Swift ◽  
T.M. Mukherjee
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Membrane Fusion ◽  
Thin Section ◽  
Structural Organization ◽  
Freeze Fracture ◽  
Goblet Cells ◽  
Mucus Production ◽  
Membrane Reorganization ◽  
Membrane Changes

Changes in the structural organization of membranes of mucous bodies and the plasma membrane that occur during mucus production in goblet cells of rat rectum have been studied by thin-section and freeze-fracture techniques. Immature mucous bodies are bounded by a trilaminar membrane and fracture faces of the membrane have randomly distributed intramembrane particles. During maturation, mucous bodies become packed tightly together and changes in the structure of their membranes include (1) fusion of apposing membranes of adjacent bodies to form a pentalaminar structure, (2) a reduction in the density of particles on membrane fracture faces, and (3) exclusion of particles from regions of membrane apposition. Some trilaminar membranes of mucous bodies fuse with the lumenal plasma membrane to form a pentalaminar structure. Sites of apposition between mucous body membranes and the lumenal plasma membrane are seen as particle-cleared bulges on fracture faces of the plasma membrane. Our results indicate that membrane reorganization associated with mucous production in goblet cells includes a reduction and redistribution of some membrane proteins and that membrane fusion occurs between portions of membranes from which proteins have been displaced.

Freeze-fracture analysis of membrane events during early neogenesis of cilia in Tetrahymena: changes in fairy-ring morphology and membrane topography

1983 ◽  
Vol 60 (1) ◽  
pp. 137-156
Author(s):  
L.A. Hufnagel
Keyword(s):  
Cell Division ◽  
Membrane Structure ◽  
Freeze Fracture ◽  
Fracture Analysis ◽  
Basal Bodies ◽  
Membrane Topography ◽  
Fairy Rings ◽  
Dividing Cells ◽  
Cortical System ◽  
Membrane Particle

A freeze-fracture analysis of early neogenesis of somatic and oral cilia of Tetrahymena was conducted using exponentially grown cultures and also cells induced to undergo oral reorganization. In this report, presumptive ciliary domains (PCDs), sites of future outgrowth of somatic cilia, are identified and their membrane structure is described in detail. The fairy ring, an array of membrane particles that occurs within the PCD and appears to be a precursor of the ciliary necklace, is described. A sequence of early stages in the formation of the ciliary necklace of somatic cilia is deduced from topographical information and membrane particle arrangements and numbers. Evidence is presented that basal bodies are seated at the cell surface prior to initiation of necklace assembly and a possible role for the basal body in necklace assembly is suggested. In dividing cells, new oral cilia grow out prior to orientation of cilia-parasomal sac complexes relative to cell axes. In dividing cells and during oral reorganization, new cilia also develop prior to their alignment into membranelles. Thus, growth of cilia is independent of their spatial orientation. Fairy rings were not observed during oral reorganization. During cell division, proliferation of new cilia is accompanied by the formation of a network of junctions between a cortical system of membranous cisternae, the cortical ‘alveoli’. These interalveolar junctions may serve as tracks for early positioning and orientation of new oral basal bodies.

scholarly journals Tetrahymena strives to maintain the fluidity interrelationships of all its membranes constant. Electron microscope evidence.

1977 ◽  
Vol 72 (3) ◽  
pp. 744-755 ◽  
Author(s):  
Y Kitajima ◽  
G A Thompson
Keyword(s):  
Endoplasmic Reticulum ◽  
Physical Properties ◽  
Growth Temperature ◽  
Freeze Fracture ◽  
Tetrahymena Pyriformis ◽  
Fixed Number ◽  
Membrane Changes ◽  
Membrane Type ◽  
Freeze Fracture Electron Microscopy ◽  
Response To Temperature

When cells of Tetrahymena pyriformis, strain NT-1, were chilled from their growth temperature of 39.5 degrees C to lower temperatures, the plasma membrane, outer alveolar, nuclear, outer mitochondrial, food vacuolar, and endoplasmic reticulum membranes each responded in a fashion quite characteristic of the membrane type. In most cases a distinctive rearrangement of intramembrane particles, as discerned by freeze-fracture electron microscopy, began abruptly at a definitive temperature. By comparing the freeze-fracture patterns of membranes in cells grown at 39.5, 27, and 15 degrees C, it was shown that the initial particle rearrangement in a given membrane always occurred at a fixed number of degrees below the growth temperature of the cell. Gradual chilling of a cell grown at constant temperature induced these membrane changes first in the outer alveolar membrane, then, in order of decreasing response to temperature, in the endoplasmic reticulum, outer mitochondrial membrane, nuclear envelope, and vacuolar membrane. The normally stable relationships between the physical properties of the several membrane types could in some cases be reversed, but only temporarily, by fatty acid supplementation or during the initial phases of acclimation to growth at a different temperature. The system provides a unique opportunity to study the effects of environmental change upon the physical properties of several functionally distinct but metabolically interrelated membranes within a single cell.

Quick-Freezing to Catch the Membrane Changes that Occur During Exocytosis

1977 ◽  
Vol 35 ◽  
pp. 676-679
Author(s):  
J.E. Heuser
Keyword(s):  
Synaptic Vesicle ◽  
Structural Changes ◽  
Freeze Fracture ◽  
Freeze Substitution ◽  
Frog Neuromuscular Junction ◽  
The Past ◽  
Synaptic Vesicle Exocytosis ◽  
Quick Freezing ◽  
Vesicle Exocytosis ◽  
Membrane Changes

The technique that we have used to capture synaptic vesicle exocytosis at the frog neuromuscular junction - that of quick-freezing muscles followed by freeze fracture (3) or freeze substitution (6) - works sufficiently well now that it may be useful in other sorts of membrane studies, or studies of fast structural changes with the electron microscope. This note reviews the quickfreezing technique we use, and describes its application to the problem of synaptic vesicle exocytosis and recycling at the synapse.Here, many of the membrane changes of interest occur during the brief delay in synaptic transmission, on a time scale of milliseconds or fractions of milliseconds, and leave only traces thereafter. In the past, we have studied these left-over traces in tissues fixed with the standard chemicals for electron microscopy (1), and have inferred from them that vesicles discharge the quanta of neurotransmitters, as the physiologists would predict.

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