scholarly journals A MORPHOLOGICAL STUDY OF HALOBACTERIUM HALOBIUM AND ITS LYSIS IN MEDIA OF LOW SALT CONCENTRATION

1967 ◽  
Vol 34 (1) ◽  
pp. 365-393 ◽  
Author(s):  
Walther Stoeckenius ◽  
Robert Rowen
Keyword(s):  
Cell Wall ◽  
Cell Membrane ◽  
Salt Concentration ◽  
Prolonged Exposure ◽  
Structural Characteristics ◽  
Wall Material ◽  
Breakdown Product ◽  
Distilled Water ◽  
Fixation Techniques ◽  
A Cell

The reported absence of a cell wall in halobacteria cannot be confirmed. Improved fixation techniques clearly show a cell wall-like structure on the surface of these cells. A stepwise reduction of the salt concentration causes the release of cell wall material before the cell membrane begins to disintegrate. The cell membrane breaks up into fragments of variable but rather small size, which are clearly different from a 4S component reported by others to be the major breakdown product of the cell membrane. It appears more likely that the 4S component arises from the dissolution of the cell wall. A residue of large membranous sheets remains even after prolonged exposure of halobacteria envelopes to distilled water. The lipids in these sheets do not differ significantly from the lipids in the lysed part of the cell membrane. The sheets, however, contain a purple-colored substance, which is not present in the lysed part. The easily sedimentable residue that remains after lysis of the cells or envelopes in distilled water also contains "intracytoplasmic membranes" with unusual structural characteristics. They can also be identified in sections through intact bacteria or envelope preparations. Their function is at present unknown but seems to be related to the formation of gas vacuoles in these organisms.

THE EFFECT OF PENICILLIN ON THE STRUCTURE OF STAPHYLOCOCCAL CELL WALLS

1959 ◽  
Vol 5 (6) ◽  
pp. 641-648 ◽  
Author(s):  
R. G. E. Murray ◽  
W. H. Francombe ◽  
B. H. Mayall
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Untreated Control ◽  
Osmium Tetroxide ◽  
Wall Material ◽  
Cell Wall Material ◽  
Cell Wall Synthesis ◽  
Cell Wall Component ◽  
A Cell ◽  
Resistant Strains

Cultures of sensitive stains of Staphylococcus aureus were fixed with osmium tetroxide after 1–5 hours' exposure to various does of pencillin and were embedded in methacrylate for sectioning and electron microscopy. They were compared with untreated, control cultures. The contrast of the cell wall material was untreated, control cultures. The contrast of the cell wall material was increased, by cutting the section of lanthanum nitrate.The cells increased in size and the surrounding cell wall was thinner than normal. The main lesions appeared in the developing cell wall septa, which showed a loss in density and gross irregularity of shape. Some questionable inclusions were seen in the cytoplasm. Lysis was prevented in a medium containing 0.3 M sucrose and the stable spheroplasts retained a recognizable cell wall after 24 hours' exposure to penicillin. However, the septa could not be demonstrated in the cells treated in sucrose medium.Two resistant strains were exposed to penicillin. In one, the cells showed no morphological effects; in the other, there was temporary damage to the cell septa with complete recovery.The observations support the hypothesis that penicillin interferes with the synthesis of a cell wall component and indicate that the main point of cell wall synthesis is at the site of septum formation.

Studies of the structure and chemical composition of the cell walls of Vaucheriaceae and Saprolegniaceae

1963 ◽  
Vol 158 (973) ◽  
pp. 435-445 ◽  
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Insoluble Fraction ◽  
Water Soluble ◽  
Hot Water ◽  
Cellulose Microfibrils ◽  
Wall Material ◽  
Native Cellulose ◽  
A Cell ◽  
Crystalline Component

The cell walls of members of the Vaucheriaceae and Saprolegniaceae have been examined by X-ray analysis and electron microscopy, and their composition determined by hydrolysis and paper partition chromatography of the hydrolysates. Both differences and similarities between the members of these two species examined are found to supplement the comparative morphological and physiological information at present available. Saprolegnia , Achlya , Brevilegnia and Dictyuchus among the Saprolegniaceae possess hot-water soluble polysaccharides containing glucose residues only. This polysaccharide is not crystallographically identical with the polysaccharide found in Vaucheria sessilis with a similar solubility. The members of the Saprolegniaceae contain large amounts of alkali-soluble polysaccharides in contrast with the negligible amount found in V. sessilis . These polysaccharides are only weakly crystalline, but the indications are that the same polysaccharides may occur through­out the Saprolegniaceae. The alkali-insoluble wall material of Vaucheria species consists of highly crystalline native cellulose with large, apparently randomly arranged, microfibrils. The hydrolysate of this material contains ribose, xylose and arabinose in addition to glucose, presumably representing strongly bound pentosans. Native cellulose also occurs in the Saprolegniaceae but only in small proportion. The bulk of the alkali-insoluble fraction in the walls of these fungi appears amorphous in the electron microscope and is only weakly crystalline. It consists of one or m ore substances containing glucose, mannose, ribose and possibly other sugars together with traces of glucosamine. These substances presumably cover the cellulose microfibrils. The total quantity of non-cellulosic polysaccharide in the Saprolegniaceae approaches 85% of the total wall weight in contrast with the situation in Vaucheria where the cellulose alone approaches 90% of the total cell wall. Dichotomosiphon is unique among the organism s studied in this paper, in possessing a cell wall entirely soluble in alkali and composed of approximately equal quantities of glucose and xylose. The crystalline component is aβ-1,3-linked xylan, as already reported for some of the Siphonales (closely related algae) by Frei & Preston.

scholarly journals Formation of wall-less cells in Kitasatospora viridifaciens requires cytoskeletal protein FilP in oxygen-limiting conditions

2020 ◽  
Author(s):  
Eveline Ultee ◽  
Ariane Briegel ◽  
Dennis Claessen
Keyword(s):  
Cell Wall ◽  
Prolonged Exposure ◽  
Electron Tomography ◽  
Cell Formation ◽  
Normal Growth ◽  
Cytoskeletal Proteins ◽  
Hyperosmotic Stress ◽  
Wall Material ◽  
Bacterial Survival ◽  
Cell Extrusion

ABSTRACTThe cell wall is considered an essential component for bacterial survival, providing structural support and protection from environmental insults. Under normal growth conditions, filamentous actinobacteria insert new cell wall material at the hyphal tips regulated by the coordinated activity of cytoskeletal proteins and cell wall biosynthetic enzymes. Despite the importance of the cell wall, some filamentous actinobacteria can produce wall-deficient S-cells upon prolonged exposure to hyperosmotic stress. Here we performed cryo-electron tomography and live cell imaging to further characterize S-cell extrusion in Kitasatospora viridifaciens. We show that exposure to hyperosmotic stress leads to DNA compaction, membrane and S-cell extrusion and thinning of the cell wall at hyphal tips. Additionally, we find that the extrusion of S-cells is abolished in a cytoskeletal mutant strain that lacks the intermediate filament-like protein FilP. Furthermore, micro-aerobic culturing promotes the formation of S-cells in the wild-type, but the limited oxygen still impedes S-cell formation in the ΔfilP mutant. These results demonstrate that S-cell formation is stimulated by oxygen-limiting conditions and dependent on the presence of an intact cytoskeleton.

scholarly journals THE EFFECT OF SALT CONCENTRATION OF THE MEDIUM ON THE RATE OF OSMOSIS OF WATER THROUGH THE MEMBRANE OF LIVING CELLS

1927 ◽  
Vol 10 (5) ◽  
pp. 665-670 ◽  
Author(s):  
Baldwin Lucke ◽  
Morton McCutcheon
Keyword(s):  
Cell Membrane ◽  
Diffusion Process ◽  
Osmotic Pressure ◽  
Salt Concentration ◽  
Sea Water ◽  
Living Cells ◽  
Water Medium ◽  
Distilled Water ◽  
Velocity Constant ◽  
Sigmoid Curve

1. Using the unfertilized egg of the sea urchin, Arbacia, as osmometer, it was found that the rate with which water enters or leaves the cell depends on the osmotic pressure of the medium: the velocity constant of the diffusion process is higher when the cell is in concentrated sea water, and lower when the sea water medium is diluted with distilled water. Differences of more than tenfold in the value of the velocity constant were obtained in this way. When velocity constants are plotted against concentration of medium, a sigmoid curve is obtained. 2. These results are believed to indicate that cells are more permeable to water when the osmotic pressure of the medium is high than when it is low. This relation would be accounted for if water should diffuse through pores in a partially hydrated gel, constituting the cell membrane. In a medium of high osmotic pressure, the gel is conceived to give up water, to shrink, and therefore to allow widening of its pores with more ready diffusion of water through them. Conversely, in solutions of lower osmotic pressure, the gel would take up water and its pores become narrow.

scholarly journals Stress-induced formation of cell wall-deficient cells in filamentous actinomycetes

2016 ◽  
Author(s):  
K. Ramijan ◽  
E. Ultee ◽  
J. Willemse ◽  
A.J. Wondergem ◽  
D. Heinrich ◽  
...  
Keyword(s):  
Cell Wall ◽  
Prolonged Exposure ◽  
Gene Clusters ◽  
Adaptation Strategy ◽  
Hyperosmotic Stress ◽  
Cell Type ◽  
Biosynthetic Gene Clusters ◽  
Resistance Determinants ◽  
A Cell ◽  
Almost All

ABSTRACTThe cell wall is a shape-defining structure that envelopes almost all bacteria. One of its main functions is to serve as a protection barrier to environmental stresses. Bacteria can be forced in a cell wall-deficient state under highly specialized conditions, which are invariably aimed at interrupting cell wall synthesis. Therefore, the relevance of such cells has remained obscure. Here we show that many filamentous actinomycetes have a natural ability to generate a new, cell wall-deficient cell type in response to hyperosmotic stress, which we call S-cells. This wall-deficient state is transient, as S-cells are able to switch to the canonical mycelial mode-of-growth. Remarkably, prolonged exposure of S-cells to hyperosmotic stress yielded variants that are able to proliferate indefinitely without their cell wall. This is the first report that demonstrates the formation of wall-deficient cells as a natural adaptation strategy and their potential transition into stable wall-less forms solely caused by prolonged exposure to osmotic stress. Given that actinomycetes are potent antibiotic producers, our work also provides important insights into how biosynthetic gene clusters and resistance determinants may disseminate into the environment.

scholarly journals Role of the Murein Precursor UDP-N-Acetylmuramyl-l-Ala-γ-d-Glu- meso-Diaminopimelic Acid-d-Ala-d-Ala in Repression of β-Lactamase Induction in Cell Division Mutants

2002 ◽  
Vol 184 (15) ◽  
pp. 4233-4239 ◽  
Author(s):  
Tsuyoshi Uehara ◽  
James T. Park
Keyword(s):  
Cell Wall ◽  
Cell Division ◽  
High Ratio ◽  
Diaminopimelic Acid ◽  
Breakdown Product ◽  
A Cell ◽  
Cell Wall Breakdown ◽  
Ts Mutant

ABSTRACT Certain β-lactam antibiotics induce the chromosomal ampC β-lactamase of many gram-negative bacteria. The natural inducer, though not yet unequivocally identified, is a cell wall breakdown product which enters the cell via the AmpG permease component of the murein recycling pathway. Surprisingly, it has been reported that β-lactamase is not induced by cefoxitin in the absence of FtsZ, which is required for cell division, or in the absence of penicillin-binding protein 2 (PBP2), which is required for cell elongation. Since these results remain unexplained, we examined an ftsZ mutant and other cell division mutants (ftsA, ftsQ, and ftsI) and a PBP2 mutant for induction of β-lactamase. In all mutants, β-lactamase was not induced by cefoxitin, which confirms the initial reports. The murein precursor, UDP-N-acetylmuramyl-l-Ala-γ-d-Glu-meso-diaminopimelic acid-d-Ala-d-Ala (UDP-MurNAc-pentapeptide), has been shown to serve as a corepressor with AmpR to repress β-lactamase expression in vitro. Our results suggest that β-lactamase is not induced because the fts mutants contain a greatly increased amount of corepressor which the inducer cannot displace. In the PBP2(Ts) mutant, in addition to accumulation of corepressor, cell wall turnover and recycling were greatly reduced so that little or no inducer was available. Hence, in both cases, a high ratio of repressor to inducer presumably prevents induction.

Infectious diseases

2012 ◽  
Author(s):  
James Carton
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Wall ◽  
Lyme Disease ◽  
Cell Membrane ◽  
Infectious Diseases ◽  
Infectious Mononucleosis ◽  
Antimicrobial Agents ◽  
Double Stranded Dna ◽  
Immunodeficiency Virus ◽  
A Cell

Microbes 16Antimicrobial agents 17Human immunodeficiency virus 18Tuberculosis 20Infectious mononucleosis 21Malaria 22Syphilis 24Lyme disease 25Leishmaniasis 26• Single-celled organisms with their double-stranded DNA lying free in cytoplasm surrounded by a cell membrane and cell wall.• Most grow in air (aerobes), but can grow without it (facultative anaerobes). Some only grow in the absence of oxygen (strict anaerobes)....

Templating Approaches Using Natural Cellular Plant Tissue

MRS Bulletin ◽  
2010 ◽  
Vol 35 (2) ◽  
pp. 145-149 ◽  
Author(s):  
Peter Greil
Keyword(s):  
Cell Wall ◽  
Plant Tissue ◽  
Cell Walls ◽  
Carbon Composite ◽  
Inert Atmosphere ◽  
Wall Material ◽  
Low Viscosity ◽  
Novel Approach ◽  
Metal Organic ◽  
A Cell

AbstractBiological preforms such as plant tissue offer a novel approach for manufacturing biomorphous ceramics with an anisotropic cellular micro- and macrostructure pseudomorphous to the natural template structure. Mimicking the hierarchical microstructure of the native template at different length scales from large vessels (mm) down to a cell wall microstructure (μm to nm) offers the possibility to tailor the local strut microstructure in biomorphous ceramics in order to improve mechanical properties at low density. Mineralization may be achieved by intercalation of the cell walls with an inorganic, metal organic, or organometallic sol. Heating above the pyrolysis temperature of the hydrocarbons forming the cell wall material in an inert atmosphere finally results in a positive replica of the cellular structure with a metal oxide/carbon composite forming the cell walls. Amorphous, nano- or microcrystalline C/Si-O-C(-N) composite materials are obtained by infiltration with a low viscosity preceramic polymeric precursor, such as polycarbosilane, -silazane, -siloxane, or a copolymer or mixture thereof. Pyrolysis into a biocarbon template and subsequent metal alloy melt or vapor infiltration and reaction at high temperatures above 1000°C is an alternate way to produce single and multiphase carbides and composites.

scholarly journals Microstructural and Texturizing Properties of Partially Pectin-Depleted Cell Wall Material: The Role of Botanical Origin and High-Pressure Homogenization

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2644
Author(s):  
Jelle Van Audenhove ◽  
Tom Bernaerts ◽  
Novita I. Putri ◽  
Erick O. Okello ◽  
Luisa Van Rooy ◽  
...  
Keyword(s):  
High Pressure ◽  
Cell Wall ◽  
Binding Capacity ◽  
Wall Material ◽  
Insoluble Residue ◽  
High Pressure Homogenization ◽  
Cell Wall Material ◽  
Botanical Origin ◽  
Water Binding ◽  
A Cell

In the current study, the texturizing properties of partially pectin-depleted cell wall material (CWM) of apple, carrot, onion and pumpkin, and the potential of functionalization by high-pressure homogenization (HPH) were addressed. This partially pectin-depleted CWM was obtained as the unextractable fraction after acid pectin extraction (AcUF) on the alcohol-insoluble residue. Chemical analysis was performed to gain insight into the polysaccharide composition of the AcUF. The microstructural and functional properties of the AcUF in suspension were studied before HPH and after HPH at 20 and 80 MPa. Before HPH, even after the pectin extraction, the particles showed a cell-like morphology and occurred separately in the apple, onion and pumpkin AcUF and in a clustered manner in the carrot AcUF. The extent of disruption by the HPH treatments at 20 and 80 MPa was dependent on the botanical origin. Only for the onion and pumpkin AcUF, the water binding capacity was increased by HPH. Before HPH, the texturizing potential of the AcUFs was greatly varying between the different matrices. Whereas HPH improved the texturizing potential of the pumpkin AcUF, no effect and even a decrease was observed for the onion AcUF and the apple and carrot AcUF, respectively.

Silica Incorporation in the Cell Wall of the Singing Cell of Urtica dioica

1975 ◽  
Vol 33 ◽  
pp. 584-585
Author(s):  
A. E. Sowers ◽  
E. L. Thurston
Keyword(s):  
Cell Wall ◽  
Unique Feature ◽  
Urtica Dioica ◽  
Wall Material ◽  
Pain Response ◽  
Apical Portion ◽  
Ultrastructural Investigation ◽  
Plant Families ◽  
Bulbous Tip

Plant stinging emergences exhibit functional similarities in that they all elicit a pain response upon contact. A stinging emergence consists of an elongated stinging cell and a multicellular pedestal (Fig. 1). A recent ultrastructural investigation of these structures has revealed the ontogeny and morphology of the stinging cells differs in representative genera in the four plant families which possess such structures. A unique feature of the stinging cell of Urtica dioica is the presence of a siliceous cell wall in the apical portion of the cell. This rigid region of the cell wall is responsible for producing the needle-like apparatus which penetrates the skin. The stinging cell differentiates the apical bulbous tip early in development and the cell continues growth by intercalary addition of non-silicified wall material until maturity.The uppermost region of the stinging cell wall is entirely composed of silica (Fig. 2, 3) and upon etching with a 3% solution of HF (5 seconds), the silica is partially removed revealing the wall consisting of individualized silica bodies (Fig. 4, 5).

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