Untersuchungen über die Ultrastruktur von Saprolegnia monoica / Ultrastructural Studies of Saprolegnia monoica

1971 ◽  
Vol 26 (8) ◽  
pp. 843-849 ◽  
Author(s):  
Herbert Hagedorn ◽  
Heinz Weinert
Keyword(s):  
Cell Wall ◽  
Nuclear Envelope ◽  
Transitional Region ◽  
Multivesicular Bodies ◽  
Ultrastructural Studies

In the tip region of a young hyphae vesicles with a diameter of 0.18 μ and vacuoles form the “Spitzenkörper”. This special differentiation is missed in old stages of hyphae. The vesicles enlarge the CM. The lomasomes in the transitional region serve for the synthesis of cell wall substances. Nuclearenvelope, ER, dictyosomes, vesicles and CM are accounted as a connecting system. The dictyogenesis from vesicles of the ER or the nuclear envelope is described. The mitochondria which occur different in the regions of the hyphae form potlike stages which contain lipoid droplets in their inside. Furthermore there occur isolated lipoid droplets which are in exchange with “polygonale bodies”, which are considered as glycoproteids. Multivesicular bodies, ER-vesicles and vacuoles are described too.

Double-membraned vesicles in Geotrichum candidum

1973 ◽  
Vol 19 (4) ◽  
pp. 534-535 ◽  
Author(s):  
S. D. Steele
Keyword(s):  
Cell Wall ◽  
Geotrichum Candidum ◽  
Ultrastructural Studies

Ultrastructural studies have demonstrated the presence of double-membraned vesicles in Geotrichum candidum Link. These vesicles were found close to the cell wall and were associated with invaginations of the plasmalemma. The role of such vesicles is discussed.

scholarly journals The Endoplasmic Reticulum and the Golgi Structures in Maize Root Cells

1959 ◽  
Vol 5 (3) ◽  
pp. 501-506 ◽  
Author(s):  
W. Gordon Whaley ◽  
Hilton H. Mollenhauer ◽  
Joyce E. Kephart
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Epoxy Resin ◽  
Maize Root ◽  
Root Tips ◽  
Animal Cells ◽  
Root Cells ◽  
Vesicular Structure

Maize root tips were fixed in potassium permanganate, embedded in epoxy resin, sectioned to show silver interference color, and studied with the electron microscope. All the cells were seen to contain an endoplasmic reticulum and apparently independent Golgi structures. The endoplasmic reticulum is demonstrated as a membrane-bounded, vesicular structure comparable in many aspects to that of several types of animal cells. With the treatment used here the membranes appear smooth surfaced. The endoplasmic reticulum is continuous with the nuclear envelope and, by contact at least, with structures passing through the cell wall. The nuclear envelope is characterized by discontinuities, as previously reported for animal cells. The reticula of adjacent cells seem to be in contact at or through the plasmodesmata. Because of these contacts the endoplasmic reticulum of a given cell appears to be part of an intercellular system. The Golgi structures appear as stacks of platelet-vesicles which apparently may, under certain conditions, produce small vesicles around their edges. Their form changes markedly with development of the cell.

scholarly journals INDIRECT VISUALIZATION OF STAPHYLOCOCCUS AUREUS PROTEIN A

1970 ◽  
Vol 131 (5) ◽  
pp. 1039-1047 ◽  
Author(s):  
D. Scott Nickerson ◽  
James G. White ◽  
Göran Kronvall ◽  
Ralph C. Williams ◽  
Paul G. Quie
Keyword(s):  
Cell Wall ◽  
Gamma Globulin ◽  
Protein A ◽  
Host Protein ◽  
Staphylococcal Protein A ◽  
Inflammatory Reactions ◽  
Host Environment ◽  
Outermost Layer ◽  
Bacterial Surface ◽  
Ultrastructural Studies

Specific but nonimmunologic reaction between staphylococcal protein A and the Fc portion of gamma globulin provided the basis for ultrastructural studies to determine the localization of protein A, using intact staphylococci and labeled myeloma gamma G-globulin. Protein A appeared to be part of the outermost layer of the staphylococcal cell wall. Strains with protein A demonstrated a coating of myeloma globulin over the entire bacterial surface. There was no coating of strains without protein A. Identification of protein A on the surface of the staphylococcal cell wall provides evidence that this may be the first material in contact with host environment. It probably accounts for apparent cross-reactions of staphylococci with antibodies to many antigens. More importantly, even in the nonimmune host protein A immunoglobulin reactivity may initiate complement activation and inflammatory reactions including chemotaxis and pus formation.

scholarly journals THE ULTRASTRUCTURE OF A MAMMALIAN CELL DURING THE MITOTIC CYCLE

1964 ◽  
Vol 21 (3) ◽  
pp. 429-463 ◽  
Author(s):  
Elliott Robbins ◽  
Nicholas K. Gonatas
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Mitotic Cycle ◽  
Mitotic Cell ◽  
Multivesicular Bodies ◽  
Chromosome Movement ◽  
Living State ◽  
Characteristic Points ◽  
Circumferential Distribution ◽  
Selection Of

With a technique of preselecting the mitotic cell in the living state for subsequent electron microscopy, it has been possible to examine the ultrastructure of the various stages of mitosis with greater precision than has been reported previously. The early dissolution of the nuclear envelope has been found to be preceded by a marked undulation of this structure within the nuclear "hof." This undulation appears to be intimately related to the spindle-forming activity of the centriole at this time. Marked pericentriolar osmiophilia and extensive arrays of vesicles are also prominent at this stage, the former continuing into anaphase. Progression of the cell through prophase is accompanied by a disappearance of these vesicles. A complex that first makes its appearance in prophase but becomes most prominent in metaphase is a partially membrane-bounded cluster of dense osmiophilic bodies. These clusters which have a circumferential distribution in the mitotic cell are shown to be derived from multivesicular bodies and are acid phosphatase-positive. The precise selection of cells during the various stages of anaphase has made it possible to follow chronologically the morphological features of the initiation of nuclear membrane reformation. The nuclear membrane appears to be derived from polar aggregates of endoplasmic reticulum, and the process begins less than 2 minutes after the onset of karyokinesis. While formation of the nuclear envelope is initiated on the polar aspects of the chromatin mass, envelope elements appear on the equatorial aspect long before the polar elements fuse. Apparently interfering with this fusion are continuous spindle tubules which traverse the chromatin mass in striking density at characteristic points. Several cortical changes, also most pronounced in anaphase, have been described, as has the kinetochore which is seen to good advantage only in this stage. The Golgi complex has been found to disappear both morphologically and histochemically during mitosis and to reappear rapidly in telophase. Evidence is presented which implicates the continuous spindle tubules in certain phases of chromosome movement.

scholarly journals Ultrastructure of the Infection of Sorghum bicolor by Colletotrichum sublineolum

2001 ◽  
Vol 91 (2) ◽  
pp. 149-158 ◽  
Author(s):  
P. S. Wharton ◽  
A. M. Julian ◽  
R. J. O'Connell
Keyword(s):  
Cell Wall ◽  
Sorghum Bicolor ◽  
Epidermal Cells ◽  
Host Cells ◽  
Wall Thickening ◽  
Fungal Cell ◽  
Resistant Cultivars ◽  
Ultrastructural Studies ◽  
Opaque Material ◽  
Colletotrichum Sublineolum

Ultrastructural studies of the infection of susceptible and resistant cultivars of Sorghum bicolor by Colletotrichum sublineolum were conducted. Initial penetration events were the same on both susceptible and resistant cultivars. Germ tubes originating from germinated conidia formed globose, melanized appressoria, that penetrated host epidermal cells directly. Appressoria did not produce appressorial cones, but each penetration pore was surrounded by an annular wall thickening. Inward deformation of the cuticle and localized changes in staining properties of the host cell wall around the infection peg suggests that penetration involves both mechanical force and enzymic dissolution. In compatible interactions, penetration was followed by formation of biotrophic globular infection vesicles in epidermal cells. Filamentous primary hyphae developed from the vesicles and went on to colonize many other host cells as an intracellular mycelium. Host cells initially survived penetration. The host plasma membrane invaginated around infection vesicles and primary hyphae and was appressed tightly to the fungal cell wall, with no detectable matrix layer at the interface. Necrotrophic secondary hyphae appeared after 66 h and ramified through host tissue both intercellularly and intracellularly, forming hypostromatic acervuli by 114 h. Production of secondary hyphae was accompanied by the appearance of electron-opaque material within infected cells. This was thought to represent the host phytoalexin response. In incompatible interactions, infection vesicles and primary hyphae were formed in epidermal cells by 42 h. However, they were encrusted with electron-opaque material and appeared dead. These observations are discussed in relation to the infection processes of other Colletotrichum spp. and the host phytoalexin response.

Mitosis in Mougeotia sp.

1972 ◽  
Vol 50 (9) ◽  
pp. 1811-1816 ◽  
Author(s):  
Carla W. Bech-Hansen ◽  
Larry C. Fowke
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Short Distance ◽  
Late Anaphase ◽  
New Information ◽  
Early Anaphase

Combined light and electron microscope observations have provided new information concerning mitosis in Mougeotia. The distribution of microtubules during division suggests that intact wall microtubules moved at preprophase to form the spindle and returned to the cell wall at telophase. During metaphase and early anaphase, chromosomal microtubules were attached to distinct kinetochores; few interzonal microtubules were evident. The subsequent elongation of the spindle at late anaphase was accompanied by the appearance of numerous interzonal microtubules and the loss of the original nuclear envelope. The nucleoli dispersed during prophase and reformed at telophase. The wall septum appeared at prophase but extended only a short distance into the cell by telophase; microtubules were not associated with the developing septum.

scholarly journals THE FORMATION OF MULTIVESICULAR BODIES FROM THE NUCLEAR ENVELOPE

1970 ◽  
Vol 45 (2) ◽  
pp. 205-211 ◽  
Author(s):  
Wincenty Kilarski ◽  
Andrzej Jasiński
Keyword(s):  
Electron Microscope ◽  
Nuclear Envelope ◽  
Perca Fluviatilis ◽  
Multivesicular Bodies ◽  
Swim Bladder ◽  
Perch Perca Fluviatilis ◽  
Mechanisms Of Formation ◽  
Gas Gland ◽  
Intense Activity ◽  
Active Proliferation

Cells of the gas gland of the perch Perca fluviatilis L., stimulated to increased generation of gas by the repeated emptying of the swim-bladder, were examined in the electron microscope. Intense activity of the nuclear envelope was demonstrated. Simple vesicles originating from the external nuclear membrane and the so-called multivesicular bodies derived from the outpocketings of both membranes of the nuclear envelope were observed. The multivesicular bodies were filled with numerous fine vesiculae arising from the active proliferation of their internal membrane. The authors offer two alternative mechanisms of formation of fine vesiculae inside the multivesicular bodies and the mechanism of the tearing away of these bodies from the nuclear envelope.

Chemical and ultrastructural studies on the distribution of sporopolleninlike biopolymers in six genera of lichen phycobionts

1985 ◽  
Vol 63 (12) ◽  
pp. 2221-2230 ◽  
Author(s):  
Ueli Brunner ◽  
Rosmarie Honegger
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Resistant Cell ◽  
Wall Layer ◽  
Conclusive Evidence ◽  
The Other ◽  
Chemical Methods ◽  
Ultrastructural Studies ◽  
Cell Wall Polymer ◽  
Infrared Absorption Spectra

Cell walls of cultured lichen phycobionts of the genera Coccomyxa, Elliptochloris, Myrmecia, Pseudochlorella, Trebouxia, and Trentepohlia were investigated with cytological and chemical methods with regard to the presence or absence of trilaminar sheaths and (or) resistant biopolymers. Trilaminar cell wall layers occurred in Coccomyxa, Elliptochloris, Myrmecia, and (less distinctly) Pseudochlorella species. A biopolymer highly resistant to nonoxidative degradation by phosphoric acid occurred only in the isolated and vigorously extracted cell walls of Coccomyxa and Elliptochloris species. The walls of all the other phycobionts, including Myrmecia and Pseudochlorella, were totally degraded, showing that a trilaminar wall layer is not conclusive evidence for the presence of a resistant cell wall polymer. The infrared absorption spectra of the degradation-resistant cell wall polymer of Coccomyxa and Elliptochloris species were not fully identical with those of natural sporopollenins. When the widely used, but chemically less appropriate acetolysis method was applied to either entire cells or isolated but not fully extracted cell walls of Coccomyxa, Elliptochloris, Myrmecia, Pseudochlorella, Trebouxia, and Trentepohlia species, they all yielded acetolysis-resistant residues whose infrared spectra resembled natural sporopollenin.

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