scholarly journals STRUCTURAL FEATURES OF MESOSOMES (CHONDRIOIDS) OF BACILLUS SUBTILIS AFTER FREEZE-ETCHING

1968 ◽  
Vol 39 (2) ◽  
pp. 251-263 ◽  
Author(s):  
N. Nanninga
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Plasma Membrane ◽  
Outer Surface ◽  
Osmium Tetroxide ◽  
Close Association ◽  
Membrane Surface ◽  
Bacterial Membranes ◽  
Inner Surface ◽  
Freeze Etching

Freeze-etched cells of Bacillus subtilis have been studied with the electron microscope. The outer surface of the plasma membrane, i.e. the side facing the cell wall, is covered with numerous granules and short strands, each measuring approximately 50 A in diameter. These strands are occasionally seen to enter the cell wall. The inner surface of the plasma membrane, i.e. the side facing the cytoplasm, appears to be sparsely dotted with small particles measuring about 50 A. The envelope of mesosomes differs from the plasma membrane. Blunt protrusions arise from its outer surface; the inner surface appears smooth. Stalked particles, as described by other investigators after negative staining with phosphotungstic acid, were not observed on any membrane surface in our material. Preparations were also made of specimens prefixed in osmium tetroxide prior to freeze-etching. Under these conditions the bacterial membranes appeared to be surprisingly well preserved. In contrast to directly frozen, unfixed cells, some osmium tetroxide-fixed preparations showed a differentiation in cytoplasm and nucleoplasm, which made it possible to observe the close association of the mesosome with the latter.

scholarly journals Subcellular localization of cellulases in auxin-treated pea.

1976 ◽  
Vol 69 (1) ◽  
pp. 97-105 ◽  
Author(s):  
A K Bal ◽  
D P Verma ◽  
H Byrne ◽  
G A Maclachlan
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Major Part ◽  
Osmium Tetroxide ◽  
Close Association ◽  
Cellulase Activity ◽  
Cytochemical Localization ◽  
Tissue Sections ◽  
Inner Surface

Two forms of cellulase, buffer soluble (BS) and buffer insoluble (BI), are induced as a result of auxin treatment of dark-grown pea epicotyls. These two cellulases have been purified to homogeneity. Antibodies raised against the purified cellulases were conjugated with ferritin and were used to localize the two cellulases. Tissue sections were fixed in cold paraformaldehyde-glutaraldehyde and incubated for 1 h in the ferritin conjugates. The sections were washed with continuous shaking for 18 h and subsequently postfixed in osmium tetroxide. Tissue incubated in unconjugated ferritin was used as a control. A major part of BI cellulase is localized at the inner surface of the cell wall in close association with microfibrils. BS cellulase is localized mainly within the distended endoplasmic reticulum. Gogli complex and plasma membrane appear to be completely devoid of any cellulase activity. These observations are consistent with cytochemical localization and biochemical data on the distribution of these two cellulases among various cell and membrane fractions.

scholarly journals PRESERVATION OF THE ULTRASTRUCTURE OF BACILLUS SUBTILIS BY CHEMICAL FIXATION AS VERIFIED BY FREEZE-ETCHING

1969 ◽  
Vol 42 (3) ◽  
pp. 733-744 ◽  
Author(s):  
N. Nanninga
Keyword(s):  
Bacillus Subtilis ◽  
Plasma Membrane ◽  
Osmium Tetroxide ◽  
Structural Changes ◽  
Uranyl Acetate ◽  
Chemical Fixation ◽  
Fixation Procedure ◽  
Etching Technique ◽  
Freeze Etching

The present study on the ultrastructure of Bacillus subtilis was undertaken in order to examine by means of the freeze-etching technique possible structural changes occurring during the chemical fixation procedure (Ryter-Kellenberger (R-K) fixation). Three stages were followed by freeze-etching, viz.: (a) fixation in osmium tetroxide, (b) fixation in osmium tetroxide and posttreatment with uranyl acetate, and (c) fixation in osmium tetroxide, posttreatment in uranyl acetate, and dehydration in a graded series of acetone. Preparations were made after each stage in the presence of 20% glycerol. Good preservation of ultrastructure was observed, after any of the three treatments, of the outer surface of the plasma membrane, and the inner surface of the plasma membrane. No alteration in fracturing properties could be observed. However, if we are to judge by the results of freeze-etching, any of the successive steps of the chemical fixation procedure achieve strong contrast between the nucleoplasmic region and the cytoplasm. Dependent on the quality of fixation, very delicately preserved DNA fibrils or strongly aggregated ones were seen. It appears that R-K fixation is capable of producing more or less distinctly visible changes in the native state of the nucleoplasm in young cells of B. subtilis.

Ultrastructure and development of urediospore ornamentation in Melampsora lini

1971 ◽  
Vol 49 (12) ◽  
pp. 2067-2073 ◽  
Author(s):  
L. J. Littlefield ◽  
C. E. Bracker
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Outer Surface ◽  
Spore Wall ◽  
Wall Material ◽  
Wild Type ◽  
Melampsora Lini ◽  
Inner Surface ◽  
External Position ◽  
Basal Portion

The urediospores of Melampsora lini (Ehrenb.) Lev. are echinulate, with spines ca. 1 μ long over their surface. The spines are electron-transparent, conical projections, with their basal portion embedded in the electron-dense spore wall. The entire spore, including the spines, is covered by a wrinkled pellicle ca. 150–200 Å thick. The spore wall consists of three recognizable layers in addition to the pellicle. Spines form initially as small deposits at the inner surface of the spore wall adjacent to the plasma membrane. Endoplasmic reticulum occurs close to the plasma membrane in localized areas near the base of spines. During development, the spore wall thickens, and the spines increase in size. Centripetal growth of the wall encases the spines in the wall material. The spines progressively assume a more external position in the spore wall and finally reside at the outer surface of the wall. A mutant strain with finely verrucose spores was compared to the wild type. The warts on the surface of the mutant spores are rounded, electron-dense structures ca. 0.2–0.4 μ high, in contrast to spines of the wild type. Their initiation near the inner surface of the spore wall and their eventual placement on the outer surface of the spore are similar to that of spines. The wall is thinner in mutant spores than in wild-type spores.

scholarly journals Paracrystalline arrays of membrane-to-membrane cross bridges associated with the inner surface of plasma membrane

1978 ◽  
Vol 77 (2) ◽  
pp. 323-328 ◽  
Author(s):  
WW Franke ◽  
C Grund ◽  
E Schmid ◽  
E Mandelkow
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Cultured Cells ◽  
Membrane Surface ◽  
Hexagonal Lattice ◽  
Interparticle Distance ◽  
Macromolecular Complexes ◽  
Inner Surface ◽  
Cross Bridges ◽  
Plasma Membrane Surface

In cultured cells of the rat kangaroo PtK2 line, veils of the cell surface were observed which consisted of only plasma membrane and paracrystalline arrays of membrane-associated particles sandwiched in between. These membrane-to-membrane cross-bridging 9-to 11-nm wide particles were somewhat coumellar-shaped and were arranged on a hexagonal lattice with an interparticle distance of 16nm. At higher magnification, they revealed an unstained core, thus suggesting a ringlike substructure. Similar arrays of paracrystal-containing veils, which were rather variable in size and frequency, were also observed in other cultured cells. It is hypothesized that these paracrystals represent protein macromolecular complexes associated with the inner plasma membrane surface which crystallize when plasma membranes come into close intracellular contact and other components of the subsurface network are removed.

The Fine-Structural Organization of the Brush Border of Intestinal Epithelial Cells

1971 ◽  
Vol 8 (3) ◽  
pp. 573-599
Author(s):  
T. M. MUKHERJEE ◽  
L. A. STAEHELIN
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Brush Border ◽  
Intestinal Epithelial Cells ◽  
Membrane Surface ◽  
Intestinal Epithelial ◽  
The Core ◽  
Unit Structure ◽  
Terminal Web ◽  
Freeze Etching

The fine structure of the brush border of intestinal epithelial cells of the mouse has been studied with both normal sectioning and freeze-etching techniques. Freeze-etching reveals the plasma membrane of the microvilli as consisting of a continuous layer, that is split during the cleaving process, in which numerous particles, 5-9 nm in diameter, are embedded, while other particle-like structures, with diameters of 7-10 nm, appear attached to the true outer membrane surface. The mucopolysaccharide surface coats of the microvilli show up more clearly in sectioned material than in freeze-etched specimens. Inside each microvillus 2 different filament systems can be demonstrated: (1) bundles of fairly closely packed and straight core microfilaments, which lead into the tip of the microvillus, and (2) short cross-filaments. Under suitable conditions the core microfilaments display a sub-unit structure with a repeating distance of approximately 6 nm. The diameter of a microfilament can vary along its length from 6 to 11 nm. Two strands of globular particles wound helically around each other seem to make up each microfilament. These and other data support the idea that the core microfilaments are actin-like. No substructure has been found on the cross-filaments, which have an orientation approximately radial to the axis of the microvilli and seem to be attached at one end to the core microfilaments and at the other to the inner surface of the microvillous membrane. The interwoven terminal web filaments also show no substructure. They form a continuous flexible platform-like structure into which the bundles of core microfilaments extend. Some terminal web filaments appear attached to the plasma membrane between the microvilli. It is suggested that the core microfilaments represent mechanical supporting elements and that the terminal web and cross-filaments are tensile elements of the brush border. In addition all 3 filament systems may also be involved in possible contractile movements of the microvilli.

THE ORGANIZATION OF CYTOPLASMIC COMPONENTS DURING THE PHASE OF CELL WALL THICKENING IN DIFFERENTIATING CAMBIAL DERIVATIVES OF ACER RUBRUM

1965 ◽  
Vol 43 (11) ◽  
pp. 1401-1407 ◽  
Author(s):  
James Cronshaw
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Osmium Tetroxide ◽  
Acer Rubrum ◽  
Middle Layer ◽  
Wall Thickening ◽  
Cytoplasmic Microtubules ◽  
Derivatives Of ◽  
Peripheral Cytoplasm

Cambial derivatives of Acer rubrum have been examined at stages of their differentiation following fixation in 3% or 6% glutaraldehyde with a post fixation in osmium tetroxide. At early stages of development numerous free ribosomes are present in the cytoplasm, and elements of the endoplasmic reticulum tend to align themselves parallel to the cell surfaces. The plasma membrane is closely applied to the cell walls. During differentiation a complex system of cytoplasmic microtubules develops in the peripheral cytoplasm. These microtubules are oriented, mirroring the orientation of the most recently deposited microfibrils of the cell wall. The microtubules form a steep helix in the peripheral cytoplasm at the time of deposition of the middle layer of the secondary wall. During differentiation the free ribosomes disappear from the cytoplasm and numerous elements of rough endoplasmic reticulum with associated polyribosomes become more evident. In many cases the endoplasmic reticulum is associated with the cell surface. During the later stages of differentiation there are numerous inclusions between the cell wall and the plasma membrane.

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.

scholarly journals Ultrastructural localization of alkaline phosphatase in rat eosinophil leucocytes.

1978 ◽  
Vol 26 (10) ◽  
pp. 862-864 ◽  
Author(s):  
D M Williams ◽  
J E Linder ◽  
M W Hill ◽  
R Gillett
Keyword(s):  
Alkaline Phosphatase ◽  
Plasma Membrane ◽  
Electron Microscope ◽  
Outer Surface ◽  
Human Neutrophil ◽  
Osmium Tetroxide ◽  
Diazonium Salt ◽  
Ultrastructural Localization ◽  
Microscope Examination ◽  
Membrane Location

The ultrastructural localization of alkaline phosphatase in eosinophil leucocytes, obtained from experimentally-induced peritoneal exudates in rats, has been studied using an osmiophilic technique with 2-naphthylthiolphosphoryl dichloride as substrate, fast Blue BBN as diazonium salt and postosmication with 1% aqueous osmium tetroxide. With this method identical incubation procedures could be used for both light and electron microscope examination. Eosinophils were the only cells which contained alkaline phosphatase. The enzyme was predominantly associated with the outer surface of the plasma membrane, being present in much lower concentrations in cytoplasmic cisternae. Eosinophil granules only rarely showed reaction product. The plasma membrane location of alkaline phosphatase in eosinophil leucocytes is identical to that recently demonstrated in the human neutrophil.

Lomasome biogenesis and function in armillaria mellea

1978 ◽  
Vol 36 (2) ◽  
pp. 402-403
Author(s):  
B. Ch. Behboodi
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Osmium Tetroxide ◽  
Higher Plants ◽  
Cell Wall Formation ◽  
Extensive Investigation ◽  
Sodium Cacodylate ◽  
Armillaria Mellea ◽  
Synthetic Media ◽  
And Function

IntroductionBorder bodies or lomasomes are the aggregation of membranes and vesicles located between the plasma membrane and the cell wall of many fungi, algae, and higher plants. Despite extensive investigation, the biogenesis as well as function of these structures is not yet known. The purpose of this investigation was to describe the biogenesis of lomasomes in Armillaria mellea and to provide some observations on their function related to cell wall formation.Materials and MethodsVarious thalli of fungi as non-aggregated hyphae, pseudosclerotes, rhizomorphs and carpophores were grown either on orange or synthetic media as described previously. The thalli were fixed in 4% glutaraldehyde buffered with 0.1 M sodium cacodylate (pH 7.4), and 0.15 M sucrose for 4 h at 4°. They were postfixed with 1% osmium tetroxide in the same buffer for 2 h at 4° and embedded in Epon according to the Luft procedure. Cytochemical studies using thiocarbohydrazide-silver proteinate were performed according the Thiéry.

scholarly journals Direct Evidence for a Radial Gradient in Age of the Apple Fruit Cuticle

2021 ◽  
Vol 12 ◽  
Author(s):  
Yiru Si ◽  
Bishnu P. Khanal ◽  
Oliver K. Schlüter ◽  
Moritz Knoche
Keyword(s):  
Cell Wall ◽  
Epidermal Cell ◽  
Outer Surface ◽  
Direct Evidence ◽  
Atmospheric Pressure Plasma ◽  
Apple Fruit ◽  
Crop Species ◽  
Radial Gradient ◽  
Inner Surface ◽  
Epidermal Cell Wall

The pattern of cuticle deposition plays an important role in managing strain buildup in fruit cuticles. Cuticular strain is the primary trigger for numerous fruit-surface disorders in many fruit crop species. Recent evidence indicates a strain gradient may exist within the apple fruit cuticle. The outer layers of the cuticle are more strained and thus more susceptible to microcracking than the inner layers. A radial gradient in cuticle age is the most likely explanation. Our study aimed to establish whether (or not) deposition of new cutin in a developing apple fruit occurs on the inner surface of the cuticle, i.e., immediately abutting the outward-facing epidermal cell wall. Developing apples were fed with 13C oleic acid through the skin. Following a 14-d period for incorporation, the fruit was harvested and the cuticular membranes (CMs) isolated enzymatically. The CMs were then ablated to varying extents from the inner or the outer surfaces, using a cold atmospheric pressure plasma (CAPP). Afterwards, the ablated CMs were dewaxed and the 13C contents were determined by mass spectrometry. The incorporation of 13C in the cutin fraction was higher than in the wax fraction. The 13C content was highest in non-ablated, dewaxed CM (DCM) and decreased as ablation depth from the inner surface increased. There was no change in 13C content when ablation was carried out from the outer surface. As fruit development proceeded, more 13C label was found towards the middle of the DCM. These results offered direct evidence for deposition of cutin being on the inner surface of the cuticle, resulting in a radial gradient in cuticular age—the most recent deposition (youngest) being on the inner cuticle surface (abutting the epidermal cell wall) and the earliest deposition (oldest) being on the outer surface (abutting the atmosphere).

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