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.

scholarly journals Halosarpheia heteroguttulata sp.nov. from submerged wood in streams

1998 ◽  
Vol 76 (11) ◽  
pp. 1857-1862 ◽  
Author(s):  
S W Wong ◽  
K D Hyde ◽  
EBG Jones
Keyword(s):  
South Africa ◽  
Hong Kong ◽  
New Species ◽  
Electron Micrographs ◽  
Basal Cell ◽  
Apical Cell ◽  
The Philippines ◽  
Submerged Wood ◽  
Transmission Electron ◽  
A New Species

A new species of Halosarpheia, H. heteroguttulata, is described from wood submerged in streams and lakes in Australia, Brunei, Hong Kong, Mauritius, the Philippines, and South Africa. It differs from other species in the genus in ascospore dimensions, and consistently large guttule(s) in the apical cell, but many smaller guttules in the basal cell. The species is illustrated with light and scanning and transmission electron micrographs and compared with other Halosarpheia species.Key words: appendage ontogeny, freshwater Ascomycete, Halosarpheia, taxonomy, ascospore ultrastructure.

Ultrastructure of conidiogenesis and appendage ontogeny in the coelomycete Bartalinia robillardoides

2003 ◽  
Vol 81 (11) ◽  
pp. 1083-1090 ◽  
Author(s):  
M KM Wong ◽  
E BG Jones ◽  
M A Abdel-Wahab ◽  
D WT Au ◽  
L LP Vrijmoed
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Cell Walls ◽  
Apical Cell ◽  
Conidiogenous Cell ◽  
Dense Layer ◽  
Basal Cells ◽  
Outer Electron ◽  
Transmission Electron ◽  
Scanning Electron

Conidiogenesis and conidial appendage ontogeny of the coelomycete Bartalinia robillardoides Tassi was studied at the light microscope, scanning electron microscope, and transmission electron microscope levels. Conidiogenesis in B. robillardoides is holoblastic. Appendage ontogeny begins as a cellular outgrowth of the apical and the basal cells of the young conidium, the former developing prior to the basal appendage. Conidia detach from the conidiogenous cells schizolytically. Mature conidial cell walls comprise two layers: an outer electron-dense layer, 30–38 nm, and an inner less electron-dense layer, 100–125 nm. The apical appendages arise from an outgrowth of the apical cell, which then branches to form the appendages. The single basal appendage arises from the junction between the basal cell of the conidium and the conidiogenous cell prior to conidial detachment from the conidiogenous cell, as an outgrowth of the conidial cell wall. Conidial appendage ontogeny is compared with those of other coelomycetes.Key words: Annellidic, appendage ontogeny, coelomycetes, holoblastic.

Ultrastructure of Conidia of the Plant Pathogenic Fungus Entomosporium Mespili

2000 ◽  
Vol 6 (S2) ◽  
pp. 688-689
Author(s):  
Elizabeth A. Richardson ◽  
Charles W. Mims
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Basal Cell ◽  
Fungal Pathogen ◽  
Pathogenic Fungus ◽  
Apical Cell ◽  
Freeze Substitution ◽  
Basal Cells ◽  
Mature Conidium ◽  
Transmission Electron

Entomosporium mespili has emerged as a significant pathogen of red tip (Photinia × fraseri), a popular and widely grown ornamental in the southeastern United States. This fungal pathogen produces its distinctive multi-celled, insect-like asexual spores or conidia (Fig. 1) in structures known as acervuli (Fig. 2) that rupture the surfaces of infected leaves. This study examines the fine structure of these conidia using a combination of scanning and transmission electron microscopy. In the case of transmission electron microscopy, conidia were prepared for study using either plunge freezing or high pressure freezing followed by freeze substitution.Each mature conidium of E. mespili consists of four to six cells (Fig. 1). These include one apical cell and one basal cell and two to four small lateral cells attached to the basal cell. The apical and lateral cells each possess a long, slender appendage. Excluding these appendages, the length of a mature conidium is usually 20-24μm while the diameters of the apical and basal cells are 8-11μm and 6-9μm respectively.

Cell wall of Fusarium sulphureum. II. Chemical composition of the conidial and chlamydospore walls

1977 ◽  
Vol 23 (6) ◽  
pp. 763-769 ◽  
Author(s):  
E. F. Schneider ◽  
L. R. Barran ◽  
P. J. Wood ◽  
I. R. Siddiqui
Keyword(s):  
Cell Wall ◽  
Glucuronic Acid ◽  
Dry Weight ◽  
Outer Wall ◽  
Wall Layer ◽  
Dense Layer ◽  
Glucose Content ◽  
Fusarium Sulphureum ◽  
Spore Walls ◽  
Wall Components

Examination of the conidial and chlamydospore walls of Fusarium sulphureum by electron microscopy showed the presence of two distinct layers of differing electron densities. These include a relatively narrow outer electron-dense layer and a broader more transparent inner layer. Both chlamydospore cell wall layers were thicker than the conidial wall. The outer wall of the chlamydospore wall was 30% thicker while the inner cell wall layer was 250% thicker than the corresponding cell wall layers in the conidia. During conidial differentiation to form chlamydospores there was a considerable augmentation of all cell wall components which varied from 7 to 26-fold per cell. The augmentation of the major cell wall constituents (N-acetylglucoseamine (NAG), glucose, and protein) and the vast increase in the inner cell wall of the chlamydospore wall indicated that these newly synthesized constituents are predominently located in the inner cell wall layer.The major carbohydrate constituents on a dry weight basis in both the conidial and chlamydospore walls were glucose, glucuronic acid, and N-acetylglycosamine (NAG). However, the proportion of these and the other carbohydrate constituents were different for both spore walls. Thus, the conidial wall contained about 50% less NAG and glucuronic acid but twice the glucose content of the chlamydospore wall. Protein was a major component of both spore walls (21.6%, conidial wall; 28.5%, chlamydospore wall). Amino acid analysis indicated differences in the types of protein present in the two spore walls. The lipid content of both conidia and chlamydospore was low (1–2%).

Haustorial development of Peronospora tabacina infecting Nicotiana tabacum

1983 ◽  
Vol 61 (12) ◽  
pp. 3444-3453 ◽  
Author(s):  
R. N. Trigiano ◽  
C. G. Van Dyke ◽  
H. W. Spurr Jr.
Keyword(s):  
Cell Wall ◽  
Toluidine Blue ◽  
Mesophyll Cell ◽  
Wall Layer ◽  
Peronospora Tabacina ◽  
Host Cytoplasm ◽  
Transmission Electron ◽  
Mold Fungus ◽  
Host Cell Wall ◽  
Hyphal Wall

The development of haustoria in tobacco by the blue-mold fungus Peronospora tabacina was examined using light, scanning, and transmission electron microscopy. Electron-lucent, callose-like appositions were observed between the host plasmalemma and the host mesophyll cell wall prior to haustorial penetration. An electron-opaque penetration matrix was present between the apposition and the host cell wall. The intercellular hyphal wall consisted of two layers which differed in staining quality. The haustorial wall was also two layered, but was primarily composed of and continuous with the inner wall layer of the intercellular hypha. Haustoria were either finger-like or branched and were encased with callose-like material. Most encasements were thickened at the proximal regions of haustoria but were thinner along the distal portions. Vesicles were present in host cytoplasm and were occasionally attached to the invaginated host plasmalemma. These vesicles might contribute to the deposition of the encasement material. The encasement stained positively for callose using aniline blue; calcofluor and toluidine blue O tests for cellulose were inconclusive, and lignin was not detected using toluidine blue O or phloroglucinol–HCl.

scholarly journals A novel exosome biogenesis mechanism: multivesicular structures budding and rupturing at the plasma membrane

2019 ◽  
Author(s):  
Stephanie Leon Quinonez ◽  
Ian R. Brown ◽  
Helen E. Grimsley ◽  
Jindrich Cinatl ◽  
Martin Michaelis ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Membrane Association ◽  
Dense Layer ◽  
Physiological Processes ◽  
Exosome Biogenesis ◽  
Transmission Electron ◽  
Typical Morphology ◽  
Intercellular Signalling ◽  
Microscopy Images

AbstractExosomes are small vesicles secreted by the cells, which mediate intercellular signalling and systemic physiological processes. Exosomes are known to originate from the intraluminal vesicles of the multivesicular endosome that fuses with the plasma membrane. We found that the non-small cell lung cancer (NSCLC) cell lines, HCC15 and A549, secreted exosomes with typical morphology and protein contents. Unexpectedly, transmission electron microscopy images indicated that the cells formed multivesicular structures that protruded from the plasma membrane and ruptured to release the exosomes. There were smooth multivesicular structures surrounded by an ordinary looking membrane, multivesicular structures coated by an electron dense layer with regular spacing pattern, and intermediate forms that combined elements of both. Electron microscopy images suggested that exosomes are release from these structures by burst events and not by the conventional fusion process. The molecular details of this novel mechanism for membrane association, deformation and fusion is to be unveiled in the future.

Salt glands in flowering culms of Eriochloa species (Poaceae)

Bothalia ◽  
1992 ◽  
Vol 22 (1) ◽  
pp. 111-117 ◽  
Author(s):  
M. O. Arriaga
Keyword(s):  
Basal Cell ◽  
Apical Cell ◽  
Salt Gland ◽  
Salt Glands ◽  
X Ray ◽  
Large Pore ◽  
Micro Analysis

Salt glands were found in Eriochloa (Paniceae-Poaceae):  E. monte\idensis, E. pseudoacrotricha and E. punctata.  They occur on the culms, rachises and secondary ramifications of the inflorescence. The glands are bicellular structures with endodermal tissue at the base. They consist of a basal cell and an apical cell, which is a collecting chamber with a large pore at the top. It is proposed to conserve the term salt gland to designate excretory structures associated with endodermal collecting tissue. The elements present in the glands (detected by the use of X-ray micro-analysis) are: Na. Mg. P. S. Cl. K with an increase of the elements from the endodermal tissue to the cap cell. Because of energy needed to transport and excrete salts, salt glands are situated at the base of the inflorescence, which is the zone of maximal development of Kranz structure. It is inferred that  Eriochloa is a facultative halophytic genus, derived recently from a halophytic ancestor.

Ultrastructural morphology of the uredium and collar formation during urediosporogenesis of Uromyces transversalis on gladiolus

1990 ◽  
Vol 68 (3) ◽  
pp. 605-612 ◽  
Author(s):  
Johan F. Ferreira ◽  
F. H. J. Rijkenberg
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Basal Cell ◽  
Basal Layer ◽  
Ultrastructural Morphology ◽  
Transmission Electron

The transverse uredia of Uromyces transversalis on gladiolus leaves were investigated by scanning and transmission electron microscopy. The basal cell forms one or more protuberances distally, each being delimited by a septum to become a urediospore initial. The initial elongates and lays down a septum to form a urediospore and pedicel. The first protuberance on the basal cell forms holoblastically, and evidence is found at the same locus for the subsequent enteroblastic formation of up to three successive urediospore initials. The pedicel wall of a spore thus formed remains on the basal cell and becomes a collar around the next protuberance. The basal layer of the two-layered septum that delimited the pedicel from the basal cell grows out to form the wall of the subsequent protuberance, and in the process ruptures and laterally displaces the terminal septal layer. A new basipetal septum forms to delimit the subsequent urediospore initial. In this manner, several collars form retrogressively and concentrically at one locus.

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.

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