Involvement of the Outer Wall Layer of Cladosporium cladosporioides in an IgG-Mediated Hypersensitivity

1988 ◽  
Vol 85 (1) ◽  
pp. 20-26 ◽  
Author(s):  
M.S. Bergen ◽  
T.J. Yang ◽  
R.P. Collins
Keyword(s):  
Outer Wall ◽  
Wall Layer ◽  
Cladosporium Cladosporioides

The ultrastructural development of the oocyst wall of Eimeria maxima

Parasitology ◽  
1980 ◽  
Vol 81 (1) ◽  
pp. 115-122 ◽  
Author(s):  
R. M. Pittilo ◽  
S. J. Ball
Keyword(s):  
Outer Wall ◽  
Amorphous Region ◽  
Wall Layer ◽  
Intestinal Cells ◽  
Type I ◽  
Type Ii ◽  
Oocyst Wall ◽  
Outer Membranes ◽  
Eimeria Maxima ◽  
Intracellular Process

SUMMARYOocyst wall formation in Eimeria maxima was studied during the macrogamete stage in intestinal cells of the chick and in unsporulated oocysts isolated from faeces. The outer of the 2 membranes bounding the mature macrogamete separated from the surface but remained as a veil surrounding the developing oocyst throughout the whole intracellular process. Wall-forming bodies Type I were initially applied to the limiting membrane of the zygote cytoplasm; a layer of material similar to their contents was then formed around the zygote. As this occurred a new double membrane was formed surrounding the oocyst cytoplasm. The outer wall layer was initially homogenous in appearance but later developed into 2 zones, an outer amorphous region and an inner osmiophilic region. The inner layer of the oocyst wall was formed from the contents of the wallforming bodies Type II which dispersed between the outer wall and the limiting membranes of the oocyst cytoplasm. There was evidence of an additional membrane formed external to the outer wall. The outer membranes were not present around the wall of oocysts passed in the faeces of chicks, but the same wall zonation was evident, although the inner osmiophilic zone of the outer wall layer was markedly thinner in comparison with the same zone seen in the tissues.

Ascospore germination, growth in culture, and imperfect spore formation in Cookeina sulcipes and Phillipsia crispata

1975 ◽  
Vol 53 (1) ◽  
pp. 56-61 ◽  
Author(s):  
J. W. Paden
Keyword(s):  
Germ Tube ◽  
Outer Wall ◽  
Wall Layer ◽  
Spore Formation ◽  
Spore Surface ◽  
No Formation ◽  
Ascospore Germination ◽  
Germ Tubes

Ascospores of Cookeina sulcipes germinate by one of two modes: (1) by the production of blastoconidia on sympodially proliferating conidiogenous cells which may arise from any point on the spore surface, and (2) by a thick polar germ tube. No ascospores were seen to germinate both ways. The conidiogenous cells are occasionally modified into narrow hyphae. The blastoconidia germinate readily but are evidently very short-lived. Ascospores of Phillipsia crispata germinate by two polar germ tubes; there is no formation of blastoconidia. In both species the inner ascospore wall separated from an outer wall layer during germination. In culture both C. sulcipes and P. crispata form arthroconidia. The arthroconidia are uninucleate; they germinate readily and reproduce the species when transferred to fresh plates.

Electron microscopy of the sporangium of Phytophthora capsici

1970 ◽  
Vol 48 (2) ◽  
pp. 221-227 ◽  
Author(s):  
W. T. Williams ◽  
R. K. Webster
Keyword(s):  
Plasma Membranes ◽  
Structural Changes ◽  
Phytophthora Capsici ◽  
Flagellar Apparatus ◽  
Outer Wall ◽  
Wall Layer ◽  
High Concentration ◽  
Zoospore Production ◽  
Apical Papilla ◽  
Ultrastructural Cytology

This paper reports results of a study on the ultrastructural cytology of sporangia of Phytophthora capsici Leonian with emphasis on flagellum formation, general sporangial structure during zoospore cleavage, and the presence, structure, and transition of cytoplasmic organelles and inclusions during these processes.Non-cleaving sporangial cytoplasm contains a high concentration of ribosomes, mitochondria, vacuoles, lipid inclusions, and endoplasmic reticular cisternae scattered throughout the cytoplasm. Nuclei in mature sporangia are located at the periphery of the cell, with their narrow poles aligned towards the plasma membrane. The apical papilla measures 4–5 × 10 μ, and is initiated as a fibrous third layer under the two-layered cell wall several microns from the apex. The outer wall layer surrounds the papilla while the inner wall narrows and disappears near the crown. The basal septal plug is a combination of the inner wall layer and slime substances.One of the first structural changes in the cytoplasm during zoospore cleavage is the genesis of the flagellar apparatus. Paired centrioles next to the narrow poles of the nuclei elongate to form kinetosomes which extend through the cytoplasm toward receptive axonemal vesicles. Axonemes then form in the axonemal vesicles. The terminal plate and its prisms account for the appearance of the axoneme when it forms above the terminal plate in the axonemal vesicle. The axonemal cylinder has a typical 9 + 2 morphology and the axonemal sheath is continuous with the axonemal vesicle tonoplast. The nucleus is an integral part of the flagellar apparatus and appears to be connected to the kinetid (axoneme + kinetosome) base via microtubules. Golgi dictyosomes occur in the sporangia during all stages of growth and may be responsible for elaboration of needed membranes during zoospore production. Osmiophilic droplets (liposomes), located within vacuoles, are a predominant feature of precleavage cytoplasm. These globules are probably lipid in nature. As cleavage begins, the liposomes become less opaque at the margins, and striations appear, eventually encompassing all or most of the liposomes at the time of cleavage. The liposomes then become less spherical and expand, filling the vacuoles. Electron-transparent regions eventually appear throughout the liposomes and the vacuolar membrane may disappear.Cleavage of the cytoplasm into zoospores occurs by the alignment and fusion of cleavage vesicles around individual nuclei. During this period organelles migrate to these centers. The cleavage vesicles coalesce with each other and the axonemal membranes, eventually becoming the plasma membranes of the daughter zoospores.

Fine structure of sporangiole development in Choanephora cucurbitarum (Mucorales)

1982 ◽  
Vol 60 (11) ◽  
pp. 2313-2324 ◽  
Author(s):  
Michael T. Higham ◽  
Kathleen M. Cole
Keyword(s):  
Electron Microscopy ◽  
Germ Tube ◽  
Tube Wall ◽  
Outer Wall ◽  
Spore Wall ◽  
Wall Layer ◽  
Choanephora Cucurbitarum ◽  
Dark Staining ◽  
Granular Vesicles ◽  
Scanning Electron

Spore development was studied in Choanephora cucurbitarum by using transmission and scanning electron microscopy. Sporangioles are produced by expansion of the ampulla wall. A two-layered spore wall is then constructed within the spine-covered sporangiole wall. The outer spore wall layer is longitudinally grooved and is devoid of spines or appendages. The inner wall layer is thinner and electron transparent. During wall production, dark-staining granular vesicles were observed in the spore cytoplasm. Their contents stained similarly to the material of the outer wall layer. Mature spores possessed a third, innermost wall layer. This was identified as a new wall layer, which was continuous with the germ-tube wall of germinated spores. Released spores were observed to be contained within the sporangiole during dispersal and germination.

Microscopy studies of Tilletia teliospore sheaths

1990 ◽  
Vol 48 (3) ◽  
pp. 706-707
Author(s):  
John S. Gardner ◽  
W. M. Hess
Keyword(s):  
Freeze Fracture ◽  
Outer Wall ◽  
Wall Layer ◽  
Wall Structure ◽  
Sample Processing ◽  
Outer Sheath ◽  
Thin Sectioning ◽  
Tilletia Controversa

Teliospores of bunts of wheat and rice have a complex multilayered wall. The outer wall layer or sheath may be absent from some Tilletia controversa teliospores and may be difficult to characterize unless it is hydrated. It may also contain surface rodlets. The sheath has been characterized with freeze fracture and thin sectioning studies. By altering the sample processing procedures and by using thin sectioning the sheath can be used to distinguish T. caries teliospores from T. controversa teliospores which is important for wheat marketing. Earlier attempts were made to distinguish the two species using SEM at low kV settings without the use of special procedures to hydrate the sheath. When many samples of each species were studied, variations in wall structure within species were evident, but at 1-15 kV the electrons penetrated the porous outer sheath and imaged the impermeable exospore layer. The purpose of these investigations was to use SEM to study hydrated sheaths of samples of T. caries and T. controversa teliospores at different kV settings.

Cell wall structures of Epicoccum nigrum (Hyphomycetes)

1973 ◽  
Vol 51 (5) ◽  
pp. 1071-1073 ◽  
Author(s):  
J. A. Brushaber ◽  
R. H. Haskins
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Outer Layer ◽  
Secondary Wall ◽  
Outer Wall ◽  
Wall Layer ◽  
Wall Material ◽  
Primary Wall ◽  
Electron Dense Material ◽  
Wall Structures

Two structurally distinct types of secondary wall layers are present in older hyphae in addition to the primary wall. A coarsely fibrous outer wall layer often becomes quite massive and frequently fuses with the outer wall layers of adjacent cells in the formation of hyphal strands. The uneven deposition of this outer layer often produces large verrucosities. The inner secondary wall layer is relatively electron transparent and contains a reticulum of electron-dense lines. The interface of the inner secondary wall with the cytoplasm is often very irregular, and sections of the plasma membrane are frequently overlain by wall material. The outer secondary wall of conidia is composed of an electron-dense material different from that of the outer wall of hyphae. Cells in the multicellular conidia tend to be polyhedral in shape with either very thick primary walls or thin primary walls having a thick inner wall deposit.

Ultrastructure of sporodochium and conidium development in the anamorphic fungus Epicoccum nigrum

2005 ◽  
Vol 83 (10) ◽  
pp. 1354-1363 ◽  
Author(s):  
C.W. Mims ◽  
E.A. Richardson
Keyword(s):  
Basal Cell ◽  
Apical Cell ◽  
Outer Wall ◽  
Wall Layer ◽  
Dense Layer ◽  
Epicoccum Nigrum ◽  
Transparent Layer ◽  
Transmission Electron ◽  
Anamorphic Fungus ◽  
Agar Surface

Scanning and transmission electron microscopy were used to examine sporodochium and conidium development in Epicoccum nigrum Link. Each sporodochium, a slightly raised mass of hyphae consisting of a pseudoparenchymous stroma covered with muriform conidia, arose from a group of loosely packed hyphae that formed on the agar surface. Conidiophores developed from the surface of the stroma. Each possessed a two-layered wall consisting of an inner electron transparent layer and an outer electron dense layer. Most conidiophores consisted of only two cells, the apical of which became swollen and gave rise to a solitary conidium initial in a holoblastic fashion. This initial enlarged and became divided into a smaller basal cell and a larger apical cell by a transverse septum. While the basal cell did not divide further, the apical cell became divided into numerous cells as the result of the formation of longitudinal and transverse septa. As a conidium matured the electron transparent inner layer of its wall thickened while the surface of its electron dense outer wall layer became transformed into small wart-like surface ornaments. Conidium secession was schizolytic and involved a transverse splitting of the septum separating the basal cell of a conidium from its conidiophore. The end of the basal cell and the tip of the conidiophore became rounded off during conidium secession.

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.

A correlation between rodlet orientation and conidiogenesis in Hyphomycetes

1973 ◽  
Vol 51 (12) ◽  
pp. 2413-2422 ◽  
Author(s):  
Garry T. Cole
Keyword(s):  
Outer Wall ◽  
Geotrichum Candidum ◽  
Progressive Increase ◽  
Wall Layer ◽  
The Other ◽  
Shape Characteristic ◽  
Developmental Relationship ◽  
Conidium Formation ◽  
Meristematic Activity ◽  
Freeze Etching

Freeze-etching has revealed changes in the orientation of rodlet fascicles on the surface of the outer wall layer of conidia and conidiogenous cells at successive stages of development. Specific patterns of rodlet fascicles reflect the progressive increase in cell volume and change in shape characteristic of 'blastic' conidium development in Gonatobotryum apiculatum. Rodlet patterns over most of the wall surface of conidia of Oidiodendron truncatum and Geotrichum candidum, on the other hand, are not significantly different from the patterns of rodlet fascicles on the wall of the determinate, fertile hyphae from which the conidia arose. This latter structural–developmental relationship is suggested to be characteristic of the 'arthric' mode of conidiogenesis. It is demonstrated, however, that conidium formation in Oidiodendron truncatum does involve some meristematic activity in addition to conversion and disarticulation of pre-existing hyphal elements. A diagrammatic interpretation of these changes in rodlet patterns during conidiogenesis is presented.

In vitro degradation of the moss Hylocomium splendens by three pleosporalean fungi

2011 ◽  
Vol 57 (5) ◽  
pp. 382-391 ◽  
Author(s):  
Melissa J. Day ◽  
Randolph S. Currah
Keyword(s):  
Vascular Plants ◽  
Outer Wall ◽  
Wall Layer ◽  
Hylocomium Splendens ◽  
In Vitro Degradation ◽  
Glacier Forefield ◽  
Mass Losses ◽  
The Family ◽  
Saxifraga Oppositifolia

Three darkly pigmented species of conidial fungi of the family Pleosporaceae isolated from plants colonizing the Saskatchewan Glacier forefield were examined for potential roles in the degradation of moss gametophytes. Curvularia inaequalis and Ulocladium atrum isolated from bryophytes Ditrichum flexicaule and Tortella tortuosa , respectively, and Chalastospora gossypii from Saxifraga oppositifolia were inoculated onto autoclaved gametophytes of the moss Hylocomium splendens. All three species of fungi caused mass losses of the moss gametophytes. In vitro enzymatic tests revealed that all three fungi degraded cellulose, while none degraded insoluble polyphenols. When this material was examined by scanning electron microscopy, it was evident that the fungi had eroded the outer wall layer of the moss leaf cells to some extent but not the inner layer containing more lignin-like compounds. Once the outer wall layer was removed, the cells easily disarticulated. It is proposed that accumulations of these phenolics-rich leaf fragments subsequently ameliorate the rooting environment for vascular plants and have the potential to support the growth of basidiomycetes and other fungi, potentially mycorrhizal with pioneer vascular plants.

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