scholarly journals THE FINE STRUCTURE OF DIPLOCOCCUS PNEUMONIAE

1964 ◽  
Vol 22 (2) ◽  
pp. 453-467 ◽  
Author(s):  
Alexander Tomasz ◽  
James D. Jamieson ◽  
Elena Ottolenghi
Keyword(s):  
Plasma Membrane ◽  
Fine Structure ◽  
Membrane System ◽  
Striking Feature ◽  
Intracytoplasmic Membrane ◽  
Intracytoplasmic Membranes

The fine structure of an unencapsulated strain of Diplococcus pneumoniae is described. A striking feature of these bacteria is an intracytoplasmic membrane system which appears to be an extension of septa of dividing bacteria. The possible function of these structures and their relationship to the plasma membrane and other types of intracytoplasmic membranes found in pneumococcus is discussed.

Methanogenesis in the absence of intracytoplasmic membranes

1984 ◽  
Vol 30 (5) ◽  
pp. 594-604 ◽  
Author(s):  
G. D. Sprott ◽  
L. C. Sowden ◽  
J. R. Colvin ◽  
K. F. Jarrell ◽  
T. J. Beveridge
Keyword(s):  
Membrane System ◽  
Accurate Method ◽  
Methanobacterium Thermoautotrophicum ◽  
Methane Formation ◽  
Bacterial Cells ◽  
Optimal Temperature ◽  
Intracytoplasmic Membrane ◽  
Methanospirillum Hungatei ◽  
Large Numbers ◽  
Intracytoplasmic Membranes

The frequency of intracytoplasmic membranes in several methanogens grown on H2–CO2 varied with the conditions of growth and varied from one strain to another. Methanobacterium thermoautotrophicum often generated large numbers of intracytoplasmic membranes, while Methanospirillum hungatei produced these membranes only rarely. Conditions allowing for rapid growth, including optimal temperature and high agitation rates, increased the production of intracytoplasmic membranes. These membranes consisted mainly of vesicles composed of one or several membrane layers, often positioned in the central region of the cytoplasm. Several mesophilic methanogens could be grown such that intracytoplasmic membranes were rarely or never observed in thin section or in replicas of cross-fractures from frozen cells. Since high rates of methane synthesis still occurred in these cultures, it follows that the intracytoplasmic membrane system is not a necessary organelle for methane formation in these strains. Negative staining for electron microscopy is not an accurate method to visualize intracytoplasmic membranes in these bacterial cells.

scholarly journals The Fine Structure of Streptomyces coelicolor

1960 ◽  
Vol 7 (3) ◽  
pp. 479-487 ◽  
Author(s):  
Audrey M. Glauert ◽  
David A. Hopwood
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Streptomyces Coelicolor ◽  
Nuclear Material ◽  
Tubular Structures ◽  
Thin Sections ◽  
Cytoplasmic Structure ◽  
Intracytoplasmic Membranes ◽  
Membranous Component

Colonies and spore suspensions of Streptomyces coelicolor were fixed by the method of Kellenberger, Ryter, and Séchaud (1958) and embedded in methacrylate or araldite. Thin sections were cut with an A. F. Huxley microtome and examined in a Siemens' Elmiskop I. At all stages of development the hyphae of Streptomyces coelicolor have an extensive membranous component in the cytoplasm. The membranes are continuous with the plasma membrane and have a variety of configurations at different places in the hyphae. Tubular structures, vesicles, and parallel stacks of membranes are seen. In some areas concentric layers of membranes form whorled structures which are particularly frequent in the region of developing cross-walls and within maturing spores. In the spores membranous structures often lie embedded in the nuclear material. In disintegrating hyphae the intracytoplasmic membranes round off into small vesicles and remain when the rest of the cytoplasmic structure has gone. In the absence of typical mitochondria and other cytoplasmic membranous structures it is possible that the membranous component of the cytoplasm of Streptomyces coelicolor may perform the functions of the endoplasmic reticulum and/or the mitochondria of higher cells.

scholarly journals THE FINE STRUCTURE OF STREPTOMYCES VIOLACEORUBER (S. COELICOLOR)

1961 ◽  
Vol 10 (4) ◽  
pp. 505-516 ◽  
Author(s):  
Audrey M. Glauert ◽  
David A. Hopwood
Keyword(s):  
Fine Structure ◽  
Aerial Mycelium ◽  
Membrane System ◽  
Cross Wall ◽  
Intracytoplasmic Membrane ◽  
Thin Sections ◽  
Gram Positive Bacteria ◽  
Outer Component ◽  
Streptomyces Violaceoruber ◽  
Germ Tubes

A study of thin sections of hyphae of Streptomyces violaceoruber in the electron microscope showed that the structure of the walls and the mode of formation of cross-walls are similar to those of Gram-positive bacteria. A beaded structure was seen in some regions of the wall, and the significance of this observation is discussed in relation to previous studies of the fine structure of bacterial cell walls. Elements of the intracytoplasmic membrane system appear to be involved in the process of cross-wall formation. The walls of the hyphae of the aerial mycelium divide into two layers before the spores are formed, and only the inner component of the wall grows inwards to form the cross-walls and so delimit the spores. The outer component remains intact for a time and acts as a sheath around the developing spores. Finally the sheath breaks and the spores are liberated. This process is contrasted with the formation of endospores in eubacteria. When the spores germinate, the walls of the germ tubes are continuous with those of the spores.

A Freeze-Etch Study of Acinetobacter SP. Grown on a Hydrocarbon Substrate

1974 ◽  
Vol 32 ◽  
pp. 174-175
Author(s):  
C. L. Scott ◽  
W. R. Finnerty
Keyword(s):  
Membrane System ◽  
Structural Distortion ◽  
Intracytoplasmic Membrane ◽  
Gram Negative ◽  
Sectioned Material ◽  
Acinetobacter Sp

Acinetobacter sp. HO-1-N, a gram-negative hydrocarbon oxidizing bacterium previously designated Micrococcus cerificans, has been shown to sequester the hydrocarbon into intracytoplasmic pools as a result of growth on this substrate. In hydrocarbon grown cells, an intracytoplasmic membrane system was also observed along with a doubling of cellular phospholipids (Z). However, using conventional dehydration and embedding procedures in preparing thin sectioned material, the hydrocarbon is extracted from the cells. This may lead to structural distortion, consequently, the freeze-etch technique was applied to preserve the integrity of the cell.

scholarly journals Caveolin-3 Associates with Developing T-tubules during Muscle Differentiation

1997 ◽  
Vol 136 (1) ◽  
pp. 137-154 ◽  
Author(s):  
Robert G. Parton ◽  
Michael Way ◽  
Natasha Zorzi ◽  
Espen Stang
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Muscle Cells ◽  
Membrane System ◽  
C2c12 Cells ◽  
Double Labeling ◽  
Specific Antibodies ◽  
T Tubules ◽  
Α1 Subunit

Caveolae, flask-shaped invaginations of the plasma membrane, are particularly abundant in muscle cells. We have recently cloned a muscle-specific caveolin, termed caveolin-3, which is expressed in differentiated muscle cells. Specific antibodies to caveolin-3 were generated and used to characterize the distribution of caveolin-3 in adult and differentiating muscle. In fully differentiated skeletal muscle, caveolin-3 was shown to be associated exclusively with sarcolemmal caveolae. Localization of caveolin-3 during differentiation of primary cultured muscle cells and development of mouse skeletal muscle in vivo suggested that caveolin-3 is transiently associated with an internal membrane system. These elements were identified as developing transverse-(T)-tubules by double-labeling with antibodies to the α1 subunit of the dihydropyridine receptor in C2C12 cells. Ultrastructural analysis of the caveolin-3– labeled elements showed an association of caveolin-3 with elaborate networks of interconnected caveolae, which penetrated the depths of the muscle fibers. These elements, which formed regular reticular structures, were shown to be surface-connected by labeling with cholera toxin conjugates. The results suggest that caveolin-3 transiently associates with T-tubules during development and may be involved in the early development of the T-tubule system in muscle.

scholarly journals THE ULTRASTRUCTURE OF CARDIAC DESMOSOMES IN THE TOAD AND THEIR RELATIONSHIP TO THE INTERCALATED DISC

1960 ◽  
Vol 8 (2) ◽  
pp. 305-318 ◽  
Author(s):  
Philip M. Grimley ◽  
George A. Edwards
Keyword(s):  
Plasma Membrane ◽  
Fine Structure ◽  
Cardiac Cells ◽  
Dense Region ◽  
Intercalated Disc ◽  
Outer Coat ◽  
Intercalated Discs ◽  
Simple Step ◽  
Contractile Forces ◽  
Band Material

The fine structure of desmosomes and intercalated discs in the toad heart is discussed. A definite relationship between the dense components of these structures and the dense region of the Z band is demonstrated. The dense region of the Z band characteristically widens at its approach to the plasma membrane, and often terminates beneath it in a distinct discoidal plaque. Cardiac desmosomes appear to be structures which result from the intimate apposition of plaques of Z band material. These desmosomes retain the Z band function as sites of attachment for myofilaments. The suggestion is made that rotation of a desmosome through 90° and splitting of filaments from the adjacent sarcomere could result in the formation of a simple step-like intercalated disc. Intermediate stages in this process are illustrated. Complex discs present in the toad probably represent the alignment of groups of simple discs produced by contractile forces. Possible physiologic functions of the disc and desmosome are discussed. Other morphologic features of toad cardiac cells include a distinct amorphous outer coat to the sarcolemma, a prominent N band, and a granular sarcoplasm with poorly developed reticulum.

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