Cellular bodies in developing chlamydospores of Thielaviopsis basicola

1977 ◽  
Vol 23 (3) ◽  
pp. 325-330 ◽  
Author(s):  
K. S. Clough ◽  
E. F. Schneider ◽  
W. L. Seaman
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Electron Microscope ◽  
Wall Thickening ◽  
Thielaviopsis Basicola ◽  
Internal Organization ◽  
Membrane Bound

The development of chlamydospores of Thielaviopsis basicola from hyphal cells involves the thickening and pigmentation of the cell wall. Electron microscope studies showed that membrane-bound cellular bodies appearing in the cytoplasm of differentiating cells developed from dilated cisternae in the endoplasmic reticulum. Within the membrane-bound bodies, vesicles of up to 0.2-μm diameter were observed which contained electron-dense particles. Vesicles resembling those seen in the cellular body were also present in the cytoplasm close to the plasmalemma. In newly formed chlamydospore cells where wall thickening was complete, the cellular bodies showed loss of internal organization, and most of the vesicles disappeared, leaving a structure resembling a vacuole. The cellular bodies were not present in undifferentiated hyphae or in mature chlamydospores.

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.

Ultrastructure of tobacco mosaic virus lesions and surrounding tissue in Phaseolus vulgaris var. Pinto

1971 ◽  
Vol 49 (3) ◽  
pp. 417-421 ◽  
Author(s):  
D. F. Spencer ◽  
W. C. Kimmins
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Phaseolus Vulgaris ◽  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Healthy Tissue ◽  
Surrounding Tissue ◽  
Infected Area ◽  
Membrane Bound

Leaves of Phaseolus vulgaris var. Pinto were inoculated with the U1 strain of tobacco mosaic virus TMV (U1) and fully expanded lesions and adjacent healthy tissue were examined in the electron microscope. Emphasis was placed on the band of healthy cells (resistant zone) surrounding the lesion, with the object of detecting the first changes in ultrastructure as healthy tissue graded into the infected area. Cells in the resistant zone were characterized by the appearance of membrane-bound vesicular bodies (paramural bodies) between the plasmalemma and cell wall. Where paramural bodies accumulated, the plasmalemma was withdrawn and intercellular cytoplasmic connections through the plasmodesmata were severed. These changes were found most frequently for a distance of about three cell diameters beyond cells visibly infected at the lesion periphery. It is suggested that these changes in ultrastructure are related to the events of localization. Spread of the virus may be inhibited because of a lack of cytoplasmic connections between cells surrounding the virus-induced lesion.

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.

The fine structure and development of chlamydospores of Fusarium oxysporum

1972 ◽  
Vol 18 (7) ◽  
pp. 997-1002 ◽  
Author(s):  
I. L. Stevenson ◽  
S. A. W. E. Becker
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Fine Structure ◽  
Electron Microscope ◽  
Cell Surface ◽  
Outer Layer ◽  
Outer Wall ◽  
Wall Layer ◽  
Thin Sections ◽  
Hyphal Wall

Methods have been developed for the rapid, reproducible induction of high-density populations of F. oxysporum chlamydospores. On transferring washed pregerminated conidia to a simple two-salts medium, chlamydospore morphogenesis was evident by 12 h and masses of mature spores could be harvested at the end of 4 days. Electron-microscope studies of thin sections of mature chlamydospores reveal a thick triple-layered cell wall. The cytoplasm contains, in addition to large lipid deposits, a nucleus, mitochondria, and endoplasmic reticulum all typical of fungal cells. Chlamydospores of F. oxysporum exhibit two distinct types of cell surface in thin section. The outer wall layer of two of the isolates studied was smooth-surfaced while the outer layer of the two other isolates was distinctly fibrillose. Some evidence is presented suggesting that the fibrillose material arises through the partial breakdown of the original hyphal wall.

Certain aspects of xylem differentiation in corn

1972 ◽  
Vol 50 (9) ◽  
pp. 1795-1804 ◽  
Author(s):  
L. M. Srivastava ◽  
A. P. Singh
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Wall Thickening ◽  
Xylem Differentiation ◽  
Cytoplasmic Protein ◽  
Wall Deposition ◽  
Vessel Elements ◽  
Parenchyma Cells ◽  
Vacuolar Membranes

Differentiation of vessel elements in corn is accompanied by marked changes in nearly all organelles except plastids. The young cells increase in volume and apparently synthesize new cytoplasmic protein. The initiation of wall thickening is accompanied by an aggregation of microtubules in specific locations and an increase in the number of mitochondria and dictyosomes. During the period of active wall deposition, the endoplasmic reticulum (ER) shows a highly elaborate form, harbors intralamellar tubules, and nearly blankets those parts of the wall which remain unthickened. Dictyosomes seem to produce at least two types of vesicles, one of which may serve as a carrier of lignin precursors. The final autolysis involves a progressive removal of vacuolar membranes, plastids, dictyosomes, vesicles associated with secretion of noncellulosic polysaccharides, microtubules, and finally plasmalemma, parts of cell wall, and cytoplasm. Mitochondria and ribosomes are degenerated. The ER probably plays an important role in this autolysis. The parenchyma cells associated with vessel elements are rich in mitochondria.

scholarly journals THE FINE STRUCTURE OF DIFFERENTIATING XYLEM ELEMENTS

1965 ◽  
Vol 24 (3) ◽  
pp. 415-431 ◽  
Author(s):  
James Cronshaw ◽  
G. Benjamin Bouck
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Fine Structure ◽  
Secondary Wall ◽  
Osmium Tetroxide ◽  
Light And Electron Microscopy ◽  
Wall Thickening ◽  
Direction Parallel ◽  
Secondary Wall Thickening ◽  
Xylem Elements

Differentiating xylem elements of Avena coleoptiles have been examined by light and electron microscopy. Fixation in 2 per cent phosphate-buffered osmium tetroxide and in 6 per cent glutaraldehyde, followed by 2 per cent osmium tetroxide, revealed details of the cell wall and cytoplasmic fine structure. The localized secondary wall thickening identified the xylem elements and indicated their state of differentiation. These differentiating xylem elements have dense cytoplasmic contents in which the dictyosomes and elements of rough endoplasmic reticulum are especially numerous. Vesicles are associated with the dictyosomes and are found throughout the cytoplasm. In many cases, these vesicles have electron-opaque contents. "Microtubules" are abundant in the peripheral cytoplasm and are always associated with the secondary wall thickenings. These microtubules are oriented in a direction parallel to the microfibrillar direction of the thickenings. Other tubules are frequently found between the cell wall and the plasma membrane. Our results support the view that the morphological association of the "microtubules" with developing cell wall thickenings may have a functional significance, especially with respect to the orientation of the microfibrils. Dictyosomes and endoplasmic reticulum may have a function in some way connected with the synthetic mechanism of cell wall deposition.

Aerial root cap structure of an orchid, Epidendrum

1981 ◽  
Vol 59 (9) ◽  
pp. 1702-1708 ◽  
Author(s):  
Susan J. Blackman ◽  
Edward C. Yeung
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Cell Walls ◽  
Root Cap ◽  
Wall Material ◽  
Wall Thickening ◽  
Cell Wall Material ◽  
Random Orientation ◽  
Mitotic Figures ◽  
Distal Cell

The root cap of Epidendrum ibaguense has a rounded profile with a root cap junction present between the cap and meristem. A distinct columella region is lacking. Mitotic figures are infrequent in the root cap initial cells. The root cap initials and their immediate derivatives show few dictyosomes, little endoplasmic reticulum, plastids lacking starch, and few vacuoles. As the cells age they increase in size and show increasing vacuolation. Plastids increase by division and accumulate large starch grains. Throughout the root cap, amyloplasts maintain a random orientation in the cell. Endoplasmic reticulum also becomes more abundant as the cells age. In older cells, hypertrophied dictyosomes are evident and cell wall material begins accumulating between the distal cell wall and the plasmalemma. Wall thickening progresses with age though radial walls remain largely unthickened. Vacuolation progresses and is followed by complete senescence leaving only the cell walls.

The Biology of Fungi

2019 ◽  
Author(s):  
Stephanie J. Smith ◽  
Rohini J. Manuel
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Germ Tube ◽  
Fungal Species ◽  
Molecular Techniques ◽  
Fungal Cell ◽  
Tube Test ◽  
Membrane Bound ◽  
Filamentous Material ◽  
One Fungus One Name

Fungi are found ubiquitously in the environment such as soil, water, and food. There are an estimated 1.5 million fungal species worldwide, although this number is felt to be grossly underestimated and is regularly updated. Of these vast numbers, around 500 fungi to date have been implicated in human disease. As opposed to bacteria, which are prokaryotes, fungi are eukaryotes, meaning they have a well-defined nucleus and have membrane- bound organelles in the cytoplasm, including an endoplasmic reticulum and a golgi apparatus. In 1969, the scientist R. H. Whittaker first proposed that organisms be classified into five kingdoms: Monera (Bacteria), Protista (Algae and Protozoans), Plantae (Plants), Mycetae (Fungi), and Animalia (Animals). Since then, there have been dramatic changes to the classifications of fungi, largely due to the appliance of phylogenetic molecular techniques. This has resulted in variances to the number of phylums, and the species assigned to them. Table 3.1 shows the seven phyla of the Fungi Kingdom. The majority of fungi pathogenic to humans inhabit the Ascomycota and Basidiomycota phyla. Fungi used to be dually named if they had a pleomorphic life cycle with sexual/ asexual stages (teleomorph/ anamorph, respectively), which meant that fungi often had two names and were classed differently. This practice was discontinued in January 2013 after the International Commission on the Taxonomy of Fungi decided that a ‘one fungus, one name’ approach should be followed. Fungi can be unicellular (yeast) or multicellular (fungi). Yeasts may look globose in nature when grown, whereas multicellular fungi grow as tubular, filamentous material called hyphae that can create a branching, hyphal network called a mycelium. Hyphae may have septa that cross their walls or be nonseptate, which is a method of differentiating fungi. An early hyphal outgrowth from a spore is called a germ tube. The germ tube test can be used to differentiate the yeasts Candida albicans and Candida dubliniensis from other Candida species. The fungal cell wall is composed of chitin and glucans, which are different components to the human cell wall. This means that they can be an effective target for antifungal therapy.

Freeze-Fracture Replication in the Ultrastructure of Blue-Green Algae

1967 ◽  
Vol 25 ◽  
pp. 74-75
Author(s):  
L. V. Leak
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Green Algae ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Electron Microscopic ◽  
Photosynthetic Membranes ◽  
Blue Green Algae ◽  
Cell Biol ◽  
Cellular Components

Electron microscopic observations of freeze-fracture replicas of Anabaena cells obtained by the procedures described by Bullivant and Ames (J. Cell Biol., 1966) indicate that the frozen cells are fractured in many different planes. This fracturing or cleaving along various planes allows one to gain a three dimensional relation of the cellular components as a result of such a manipulation. When replicas that are obtained by the freeze-fracture method are observed in the electron microscope, cross fractures of the cell wall and membranes that comprise the photosynthetic lamellae are apparent as demonstrated in Figures 1 & 2.A large portion of the Anabaena cell is composed of undulating layers of cytoplasm that are bounded by unit membranes that comprise the photosynthetic membranes. The adjoining layers of cytoplasm are closely apposed to each other to form the photosynthetic lamellae. Occassionally the adjacent layers of cytoplasm are separated by an interspace that may vary in widths of up to several 100 mu to form intralamellar vesicles.

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

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