Ultrastructure of conidiogenesis in Drechslera sorokiniana

1973 ◽  
Vol 51 (3) ◽  
pp. 629-638 ◽  
Author(s):  
Garry T. Cole
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Outer Wall ◽  
Conidiogenous Cell ◽  
Ultrastructural Examination ◽  
Transmission Electron ◽  
Conidium Formation ◽  
Microscopic Studies ◽  
Relationship Of

An ultrastructural examination of conidiogenesis in Drechslera sorokiniana reveals that conidia develop enteroblastically through channels in the conidiogenous cell wall. These channels probably form by autolysis of the outer wall layers. The data support earlier concepts based on light-microscopic studies of conidium ontogeny in this and other developmentally related species of hyphomycetes. The surface morphology and relationship of wall layers of the conidium and conidiogenous cell at various stages of development are illustrated by scanning and transmission electron microscopy, respectively. This information is summarized in a diagrammatic interpretation of conidiogenesis. Cytodifferentiation during conidium formation and conidiogenous cell proliferation is also examined. A possible association between organelle migration in developing conidiogenous cells and fascicles of microfibrils, proposed in an earlier paper, is discussed. A suggestive explanation is presented for the accumulation of microbodies in conidium initials and apices of proliferating conidiogenous cells. Layers of endoplasmic reticulum which are terminally hypertrophied and juxtaposed to the plasma membrane of developing conidiogenous cells are also noted.

scholarly journals Chemical composition, anatomy, lignin distribution, and cell wall structure of Malaysian plant waste fibers

BioResources ◽  
2006 ◽  
Vol 1 (2) ◽  
pp. 220-232 ◽  
Author(s):  
H. P. S. Abdul Khalil ◽  
M. Siti Alwani ◽  
A. K. Mohd Omar
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Chemical Composition ◽  
Cell Wall Structure ◽  
Wall Structure ◽  
Anatomical Characteristics ◽  
Lignin Distribution ◽  
Transmission Electron ◽  
Palm Frond

The chemical composition, anatomical characteristics, lignin distribution, and cell wall structure of oil palm frond (OPF), coconut (COIR), pine-apple leaf (PALF), and banana stem (BS) fibers were analyzed. The chemical composition of fiber was analyzed according to TAPPI Methods. Light microscopy (LM) and transmission electron microscopy (TEM) were used to observe and determine the cell wall structure and lignin distribution of various agro-waste fibers. The results revealed differences in anatomical characteristics, lignin distributions, and cell wall structure of the different types of fibers investigated. Nevertheless, transmission electron microscopy (TEM) micrographs have confirmed that the well wall structure, in each case, could be described in terms of a classical cell wall structure, consisting of primary (P) and secondary (S 1 , S 2 , and S 3 ) layers.

Localized dissolution of grain boundary T1 precipitates in Al-3Cu-2Li

2015 ◽  
Vol 33 (6) ◽  
pp. 395-401 ◽  
Author(s):  
Ramasis Goswami
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundary ◽  
Orientation Relationship ◽  
S Phase ◽  
Dissolution Behavior ◽  
Moist Air ◽  
Orientation Relation ◽  
Transmission Electron ◽  
Relationship Of

AbstractTransmission electron microscopy (TEM) was employed to investigate the dissolution behavior of nanocrystalline grain boundary T1 precipitates in Al-3Cu-2Li. These grain boundary T1 plates exhibit an orientation relation with matrix, with the (1-11)α-Al parallel to (0001)T1 and [022]α-Al parallel to [10-10]T1, which is similar to the orientation relationship of T1 plates formed within grains. TEM studies showed that these grain boundary T1 plates react readily in moist air. As a result of the localized dissolution, the Cu-rich clusters form onto T1, which is consistent with the localized dissolution behavior observed in nanocrystalline S phase in Al-Cu-Mg.

scholarly journals Root Resorption on Torqued Human Premolars Shown by Tartrate-Resistant Acid Phosphatase Histochemistry and Transmission Electron Microscopy

2006 ◽  
Vol 76 (6) ◽  
pp. 1015-1021 ◽  
Author(s):  
Mauricio A. Casa ◽  
Rolf M. Faltin ◽  
Kurt Faltin ◽  
Victor E. Arana-Chavez
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Acid Phosphatase ◽  
Root Resorption ◽  
Biomechanical Model ◽  
Applied Force ◽  
Tartrate Resistant Acid Phosphatase ◽  
Ultrastructural Examination ◽  
Transmission Electron ◽  
Root Surfaces

Abstract Objective: To identify clastic cells on the root surfaces of torqued human premolars. Materials and Methods: A continuous force of 600 cNmm was applied to upper first premolars in patients 13–16 years of age by using a precise biomechanical model with superelastic wires (NiTi-SE). The 28 teeth in 14 patients were divided into five groups (control [nonmoved], and moved for either 1, 2, 3, or 4 weeks) and processed for tartrate-resistant acid phosphatase (TRAP) histochemistry and transmission electron microscopy. Results: Mononuclear TRAP-positive cells appeared at 2 weeks, wheras large multinucleated TRAP-positive cells were numerous at 3 and 4 weeks. Ultrastructural examination revealed many clastic cells in contact with resorption lacunae. In addition, some cementoblast-like cells appeared secreting new cementum over previously resorbed lacunae. Conclusions: In general, resorption lacunae and the number of clastic cells, which increased with the duration of the applied force, were found on the cementum surface at the pressure areas. Some signs of cementum repair were also noticed, even with the maintenance of the level of the force.

Ultrastructure of hyperparasitism of Coniothyrium minitans on sclerotia of Sclerotinia sclerotiorum

1987 ◽  
Vol 65 (12) ◽  
pp. 2483-2489 ◽  
Author(s):  
H. C. Huang ◽  
E. G. Kokko
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Sclerotinia Sclerotiorum ◽  
Cell Walls ◽  
Chemical Activity ◽  
Coniothyrium Minitans ◽  
Medullary Tissue ◽  
Transmission Electron

Transmission electron microscopy revealed that hyphae of the hyperparasite Coniothyrium minitans invade sclerotia of Sclerotinia sclerotiorum, resulting in the destruction and disintegration of the sclerotium tissues. The dark-pigmented rind tissue is more resistant to invasion by the hyperparasite than the unpigmented cortical and medullary tissues. Evidence from cell wall etching at the penetration site suggests that chemical activity is required for hyphae of C. minitans to penetrate the thick, melanized rind walls. The medullary tissue infected by C. minitans shows signs of plasmolysis, aggregation, and vacuolization of cytoplasm and dissolution of the cell walls. While most of the hyphal cells of C. minitans in the infected sclerotium tissue are normal, some younger hyphal cells in the rind tissue were lysed and devoid of normal contents.

Poly(β-hydroxybutyrate) extrusion from pleomorphic cells ofAzotobacter vinelandiiUWD

1995 ◽  
Vol 41 (13) ◽  
pp. 22-31 ◽  
Author(s):  
William J. Page ◽  
Luis D'elia ◽  
Richard Sherburne ◽  
Lori L. Graham
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Azotobacter Vinelandii ◽  
Intact Cell ◽  
Viable Cell ◽  
Transmission Electron ◽  
Polymer Expansion ◽  
Chemical Dehydration ◽  
Pleomorphic Cells

Azotobacter vinelandii UWD cells fill with up to 80% (per dry mass) poly(β-hydroxybutyrate) (PHB) after 24 h growth in medium containing sugars and fish peptone. However, peptones were not usually added to Azotobacter culture as they induced pleomorphism and compromised cell wall strength. This study examines the morphology of these PHB-producing pleomorphic cells in the transmission electron microscope. PHB-producing cells incubated for 18–24 h were most frequently 2–3 μm diameter spheres containing up to 20 PHB inclusions/cross section, or a calculated ≈ 100 inclusions/cell volume. These inclusions tended to be of small size (≈ 0.5 μm diameter) and became fewer and larger in older cells. The most striking feature of these pleomorphic cells was the apparent extrusion of polymer from the cells. It is unlikely that PHB extrusion is an active process from a viable cell as there was considerable cell wall damage at the point of polymer extrusion. The results suggest that the extrusion of PHB may be the result of polymer expansion, caused by the dehydration of the specimen for transmission electron microscopy, coupled with the inability of the pleomorphic cell wall to retain the expanding polymer. Thus, freeze-substituted sections of similar cells that were prepared without chemical dehydration did not extrude PHB. However, lysed cells prepared for transmission electron microscopy by chemical dehydration also did not extrude PHB, which suggests differences in the fluidity of the PHB in intact cell inclusions and lysed cell granules.Key words: poly(β-hydroxybutyrate), inclusions, polymer expansion, dehydration artifact.

Transmission Electron Microscopy of Unfrozen and Frozen/Thawed Cells of Listeria monocytogenes Treated With Lipase and Lysozyme

1992 ◽  
Vol 55 (9) ◽  
pp. 687-696 ◽  
Author(s):  
SOUZAN E. EL-KEST ◽  
ELMER H. MARTH
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Listeria Monocytogenes ◽  
Storage Time ◽  
Frozen Storage ◽  
Activity Type ◽  
Protoplast Formation ◽  
Transmission Electron ◽  
Three Stages

Unfrozen cells of Listeria monocytogenes typically contained no preplasma space exterior to the plasma membrane (PM) when viewed by transmission electron microscopy. Cells of L. monocytogenes strains Scott A, V7, and California (CA), after freezing and frozen storage, exhibited one or more of the following when viewed with transmission electron microscopy: (a) retraction of cytoplasm and infolding of the PM to form mesosomes, (b) extra-and intracellular rupture of the cell wall (CW), (c) formation of intracellular “bubbles,” and (d) damage to the CW and PM that could have resulted from autolysin activity. Type and degree of effect depended on frozen storage time and strain of L. monocytogenes. Lysozyme treatment of unfrozen or frozen/stored (19 d)/thawed cells of strains Scott A, V7, and CA resulted in protoplast formation and damage to the CW. Three stages of protoplast formation were observed when cells of strain CA were frozen, stored 2 weeks, thawed, and treated with lysozyme. More damage to the CW and PM occurred when frozen storage time was extended for up to 6 weeks before treatment with lysozyme. Lipase and lysozyme treatment of unfrozen or frozen/stored (19 d)/thawed cells of strain Scott A resulted in protoplast formation with some damage to the PM and irregularity in shape of cells. Damage to the PM increased with increasing frozen storage time for up to 6 weeks. Some cells of strain CA resisted freezing, frozen storage for 6 weeks, thawing, and treatment with lipase and lysozyme.

Electron Microscopy Studies of Polymer Blends

1980 ◽  
Vol 38 ◽  
pp. 248-249
Author(s):  
S.Y. Hobbs ◽  
V.H. Watkins ◽  
R.P. Kambour ◽  
R.C. Bopp
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phase Separation ◽  
Phase System ◽  
Segregation Behavior ◽  
Phenylene Oxide ◽  
Transmission Electron ◽  
Microscopic Studies ◽  
Phase Separation Behavior ◽  
Separation Behavior

Scanning and transmission electron microscopy have been used to investigate the phase separation behavior of blends of brominated poly (2,6-dimethy1 -1 ,4-phenylene oxide) known trivially as poly (xylenyl ether) (PXE) and polystyrene. DSC scans show that when more than 85% of the PXE rings are brominated, the blends exhibit two glass temperatures centered at 100°C and 290°C and the polymers are immiscible.1 At lower bromine concentrations, a single composition dependent Tg characteristic of a one phase system is observed. Microscopic studies, however, indicate that separate phases which can not be detected ca1orimetrica11y may persist to considerably lower levels of bromination and may thus provide a more sensitive measure of segregation behavior.

scholarly journals Swelling of Valonia cellulose microfibrils in amine oxide systems

2008 ◽  
Vol 86 (6) ◽  
pp. 520-524 ◽  
Author(s):  
Pierre Noé ◽  
Henri Chanzy
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Electron Diffraction ◽  
Amine Oxide ◽  
Cellulose Microfibrils ◽  
Electron Diffraction Analysis ◽  
Oxide Systems ◽  
Transmission Electron ◽  
Valonia Ventricosa

Cellulose microfibrils from Valonia ventricosa cell-wall fragments were immersed into molten N-methylmorpholine-N-oxide monohydrate (NMMO·H2O), stabilized with n-propyl gallate and kept at 80 °C. The resulting ultrastructural modifications, which were followed by transmission electron microscopy and electron diffraction analysis, showed that within minutes the solvent slowly penetrated inside the crystalline microfibrils and progressed as a wedge in between the cellulose chains without cutting them. Prior to dissolution, a longitudinal subfibrillation of the initial microfibrils occurred, leading to the observation of highly swollen microfibrils, which could reach diameters up to three times larger than those of the initial samples. This mode of swelling is compared with those occurring in other systems, where the intracrystalline swelling of cellulose has been described at the ultrastructural level.Key words: cellulose swelling, Valonia cellulose, N-methylmorpholine-N-oxide.

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