Ultrastructure of Chlamydomonas eugametos as revealed by freeze-etching: cell wall, plasmalemma and chloroplast membrane

1974 ◽  
Vol 47 (2) ◽  
pp. 125-141 ◽  
Author(s):  
D.F. Bray ◽  
Kazuo Nakamura ◽  
J.W. Costerton ◽  
E.B. Wagenaar
Keyword(s):  
Cell Wall ◽  
Chloroplast Membrane ◽  
Chlamydomonas Eugametos ◽  
Freeze Etching

The eyespot of Chlamydomonas eugametos: a freeze-etch study

1973 ◽  
Vol 51 (4) ◽  
pp. 817-819 ◽  
Author(s):  
Kazuo Nakamura ◽  
D. F. Bray ◽  
J. W. Costerton ◽  
E. B. Wagenaar
Keyword(s):  
Cleavage Plane ◽  
Chloroplast Membrane ◽  
Ordered Arrays ◽  
Chlamydomonas Eugametos

The ultrastructure of the eyespot region of Chlamydomonas eugametos was studied with the freeze-etch technique. In the region of the eyespot the outer chloroplast membrane, when fractured medially, showed the presence of bulgings which appeared as either depressions or bumps depending on the cleavage plane. These deformations of the outer chloroplast membrane produced by the granules of the eyespot are about 80 mμ in diameter and form ordered arrays of 800 or more particles.

The maturation of cell wall structure during germination of Bacillus polymyxa spores

1970 ◽  
Vol 16 (9) ◽  
pp. 883-887 ◽  
Author(s):  
R. G. E. Murray ◽  
Myrtle M. Hall ◽  
J. Marak
Keyword(s):  
Cell Wall ◽  
Intermediate Layer ◽  
Single Layer ◽  
Regular Structure ◽  
Wall Structure ◽  
Bacillus Polymyxa ◽  
Rectangular Array ◽  
Crack Open ◽  
Freeze Etching ◽  
Primordial Cell

Sections of germinating spores of Bacillus polymyxa show that the primordial cell wall consists of a single layer. The intermediate layer and an outer rectangular array of macromolecules found on vegetative cells do not appear until the spore coats crack open about 60 min after initiation of germination. The initial areas of the new components appear in patches under the cracks in the coats. Within 10 min the wall is completed and takes on the profile seen in the vegetative cell. Negative staining and freeze-etching techniques show the regular structure to be identical with that previously shown for mature cells, although the subunits are more readily visible in negatively stained preparations.

Fine Structure of Swarmers of Cladophora and Chaetomorpha

1971 ◽  
Vol 9 (3) ◽  
pp. 581-601
Author(s):  
D. G. ROBINSON ◽  
R. D. PRESTON
Keyword(s):  
Cell Wall ◽  
Fine Structure ◽  
Spatial Arrangement ◽  
Cell Wall Synthesis ◽  
Fibrous Layer ◽  
Etching Technique ◽  
Freeze Etching

Naked swarmers of both Cladophora rupestris and Chaetomorpha melagonium have been examined by the freeze-etching technique. The swarmers of Cladophora, collected just after settling, reveal several layers of granules external to the plasmalemma and internal to the so-called ‘fibrous-layer’. Chaetomorpha swarmers collected just before settling show extrusion of vesicles through the plasmalemma. The structures associated with the membranes are discussed in relation to known features of these swarmers already observed by sectioning. The role of granules in the synthesis of cell wall microfibrils is strengthened though the spatial arrangement of the granules seen in this investigation does not completely fulfil the ‘ordered granule’ hypothesis. Description of, and comments on, features related to cell wall synthesis, particularly the Golgi and vacuolar systems, are given.

The cell wall of Chlamydomonas eugametos. Immunological aspects

Planta ◽  
1983 ◽  
Vol 158 (1) ◽  
pp. 82-89 ◽  
Author(s):  
Alan Musgrave ◽  
Piet de Wildt ◽  
Rob Broekman ◽  
Herman van den Ende
Keyword(s):  
Cell Wall ◽  
Chlamydomonas Eugametos

Comparative ultrastructure of selected oral streptococci: thin-sectioning and freeze-etching studies

1976 ◽  
Vol 22 (4) ◽  
pp. 475-485 ◽  
Author(s):  
Stanley C. Holt ◽  
E. R. Leadbetter
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Cytoplasmic Membrane ◽  
Close Association ◽  
Oral Streptococci ◽  
Outermost Layer ◽  
Thin Sectioning ◽  
Freeze Etching ◽  
Comparative Ultrastructure ◽  
Crystalline Array

The ultrastructure of Streptococcus mutans, serotypes a–e, S. sanguis, S. mitis, and S. salivarius HHT, were examined by the techniques of thin-sectioning and freeze-etching. The cell walls varied in width between 15 and 46 nm and were covered with an electron-dense fibrillar or fuzz layer. The cytoplasmic membrane was in close association with numerous mesosomes which were, in turn, either closely associated or in contact with the bacterial chromosome. In freeze-etch replicas, the outermost layer of the cell wall was fibrous, and the cytoplasmic membrane was covered with particles composed of several subunits. Both particle-clusters and particle-free areas occurred on the surfaces of the cytoplasmic membrane, as well as a crystalline array in the ground plasm of the cell.

Contractile elements of Lemna trisulca L. glycerinated cell models during chloroplast translocations

2000 ◽  
Vol 78 (4) ◽  
pp. 503-510
Author(s):  
Robert A Rinaldi ◽  
Barbara Kalisz-Nowak ◽  
Wlodzimierz Korohoda ◽  
Stanislaw Wieckowski ◽  
Wincenty Kilarski ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Contractile Element ◽  
Cell Models ◽  
Chloroplast Membranes ◽  
Chloroplast Membrane ◽  
Membrane Cell

Electron microscopy of Lemna glycerinated cell models depicts contractile elements during chloroplast translocations. One contractile element, the thin ectoplasmic layer, is [Formula: see text] 0.4 µm thick, pressed against plasma membrane-cell wall. Thin ectoplasmic layer contains numerous oriented filaments and some appear to be actin and myosin. Another contractile element is the outer chloroplast membrane which envelops each chloroplast and joins or fuses with the thin ectoplasmic layer. Choroplast interconnections are formed between two or more chloroplasts by outer chloroplast membranes; they enhance chloroplast communications, translocations, and molecular exchanges.Key words: chloroplast translocations, contractility, tubular connections.

Surface charge and morphogenesis of regular arrays of macromolecules on bacterial cell walls

1978 ◽  
Vol 36 (2) ◽  
pp. 346-347 ◽  
Author(s):  
U. B. Sleytr ◽  
G. P. Friers
Keyword(s):  
Cell Wall ◽  
Surface Charge ◽  
Bacterial Cell ◽  
Cell Walls ◽  
Surface Layers ◽  
Regular Surface ◽  
Wide Range ◽  
Freeze Etching ◽  
Regular Arrays ◽  
Peptidoglycan Layer

Regular arrays of macromolecules can be demonstrated on the surface of a wide range of bacteria by negative staining and freeze-etching techniques. The isolated subunits of the regular surface layers (S-layers) examined in this study have shown to consist of protein or glycoprotein and to possess the ability to assemble spontaneously under certain conditions to form regular arrays with the same dimensions as those seen on intact bacteria. In appropriate conditions the isolated subunits reattach to the cell wall from which they have been removed. Analysis of the orientation of the reconstituted S-layers have shown that the pattern of the regular arrays seem to be determined only by the directional bonds between the subunits and not by any order in the underlying (peptidoglycan) layer.

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