Morphogenesis of arthroconidiation in the dermatophyte Trichophyton mentagrophytes with special reference to wall ontogeny

1984 ◽  
Vol 30 (11) ◽  
pp. 1415-1421 ◽  
Author(s):  
Tadayo Hashimoto ◽  
R. G. Emyanitoff ◽  
R. C. Mock ◽  
J. H. Pollack
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Trichophyton Mentagrophytes ◽  
Outer Wall ◽  
Time Lapse ◽  
Wall Layer ◽  
Spore Surface ◽  
Inner Surface ◽  
Initial Sign ◽  
Hyphal Wall

The formation of arthroconidia, especially the ontogeny of the arthroconidial wall in the dermatophyte Trichophyton mentagrophytes, was investigated by light and electron microscopy. Time-lapse photomicroscopy revealed that the new septa were inserted regularly along the length of the hypha. Each new septum divided a preexisting hyphal segment into approximately equal halves. The initial sign of arthroconidium formation detected by electron microscopy was the deposition of a conidium-specific wall layer on the inner surface of the preexisting hyphal wall. The invaginating septal material was continuous with the newly deposited inner wall layer of the sporulating hyphae. When septation was completed, the septum and septal furrow were continuous across the wall to the inner edge of the outer wall layer. After septation, the inner wall continued to thicken until it attained the thickness of a mature arthroconidial wall (0.3 – 0.5 μm). Simultaneously, immature arthroconidia continued to swell and eventually assumed a barrel shape. When disarticulated, arthroconidia were surrounded by the newly formed conidial wall at the poles, and the sides of the conidia were additionally bounded by the residual hyphal wall. As the arthroconidia matured, the remnants of the hyphal wall tended to be detached from the spore surface. From these observations we conclude that T. mentagrophytes formed arthroconidia by the enteroarthric mode rather than the holoarthric process as previously described.

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.

scholarly journals SURFACE SPECIALIZATIONS OF FUNDULUS CELLS AND THEIR RELATION TO CELL MOVEMENTS DURING GASTRULATION

1967 ◽  
Vol 32 (1) ◽  
pp. 139-153 ◽  
Author(s):  
J. P. Trinkaus ◽  
Thomas L. Lentz
Keyword(s):  
Electron Microscopy ◽  
Intercellular Space ◽  
Plasma Membranes ◽  
Time Lapse ◽  
Cell Movements ◽  
Membrane Activity ◽  
Inner Surface ◽  
Apical Junctions ◽  
Controlled Flow ◽  
Marginal Cells

Cell movements in Fundulus blastoderms during gastrulation were studied utilizing time-lapse cinemicrography and electron microscopy. Time-lapse films reveal that cells of the enveloping layer undulate and sometimes separate briefly but remain together in a cohesive layer. During epiboly, the marginal enveloping layer cells move over the periblast as it expands over the yolk sphere. Movement occurs as a result of ruffled membrane activity of the free borders of the marginal cells. Deep blastomeres become increasingly active during blastula and gastrula stages. Lobopodia project from the blastomeres in blastulae and adhere to other cells in gastrulae, giving the cells traction for movement. Contact specializations are formed by the lateral adjacent plasma membranes of enveloping layer cells. An apical junction is characterized by an intercellular gap of 60–75 A. Below this contact, the plasma membranes are separated by 120 A or more. In mid-gastrulae, cytoplasmic fibrils occur adjacent to some apical junctions, and small desmosomes appear below the apical junction. Septate desmosomes also appear at this time. A junction with an intercellular gap of 60 A occurs between marginal enveloping layer cells and periblast. Contacts between deep blastomeres become numerous in gastrulae and consist of contacts at the crests of surface undulations, short areas of contact in which the plasma membranes are 60 or 120 A apart, and long regions characterized by a 200-A intercellular gap. Lobopodia contact other blastomeres only in gastrulae. These junctions contain a 200-A intercellular space. Some deep blastomeres are in contact with the tips of periblast microvilli. The mechanism of epiboly in Fundulus is discussed and reevaluated in terms of these observations. The enveloping layer is adherent to the margin of the periblast and moves over it as a coherent cellular sheet. Periblast epiboly involves a controlled flow of cytoplasm from the thicker periblast into the thinner yolk cytoplasmic layer with which it is continuous. Deep cells move by adhering to each other, to the inner surface of the enveloping layer, and to the periblast.

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.

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.

Saltatory Movements of Organelles in Intact Nerves of Rhodnius Prolixus STÅL

1977 ◽  
Vol 70 (1) ◽  
pp. 247-257
Author(s):  
J. P. HESLOP ◽  
E. A. HOWES
Keyword(s):  
Electron Microscopy ◽  
High Power ◽  
Light Microscope ◽  
Light And Electron Microscopy ◽  
Time Lapse ◽  
Rhodnius Prolixus ◽  
Axonal Flow ◽  
Different Temperatures ◽  
Intracellular Organelles

1. Abdominal nerves of Rhodnius prolixus were studied with the light microscope under high-power Nomarski optics with a minimum of surgical interference. The preparation was perfused with bathing solutions which could be changed during time-lapse cinematography. 2. The structure of the nerve trunks was studied by light and electron microscopy. 3. The movements of intracellular organelles are described and discussed. 4. Saltatory movements of organelles, probably mitochondria, were followed at different temperatures. Rate of saltation varied linearly with temperature. 5. Axonal flow (bulk movement of cytoplasm) did not occur in healthy abdominal nerves.

scholarly journals Terminal phase of cytokinesis in D-98S cells

1977 ◽  
Vol 73 (3) ◽  
pp. 672-684 ◽  
Author(s):  
J Mullins ◽  
JJ Biesele
Keyword(s):  
Electron Microscopy ◽  
Significant Contribution ◽  
Light And Electron Microscopy ◽  
Time Lapse ◽  
Nuclear Material ◽  
Terminal Phase ◽  
Serial Sectioning ◽  
Intercellular Bridge ◽  
Daughter Cells ◽  
Complete Breakdown

The events leading to the completion of cytokinesis after the formation of the midbody and intercellular bridge in D-98S cells were studied with light and electron microscopy. Pairs of daughter cells corresponding to different stages of cytokineses, as determined previously form time lapse films, were selected from embedded monolayers for serial sectioning. Separation of daughter cells is preceded by the reduction in diameter of the intercellular bridge from 1-1.5 μm to approx. 0.2 μm. Two processes contribute to this reduction: (a) The intercellular bridge becomes gradually thinner after telophase; a progressive breakdown of midbody structures accompanies this change; and (b) the more significant contribution to reduction in bridge diameter occurs through the localized constriction of a segment of the intercellular bridge.. The microtubules within the constricted portion of the bridge are forced closer together, and some microtubules disappear as this narrowing progresses. The plasma membrane over the narrowed segments is thrown into a series of wavelike ripples. Separation of daughter cells is achieved through movements of the cells which stretch and break the diameter-reduced bridge. The midbody is discarded after separation and begins to deteriorate. Occasional pairs of daughter cells were found in which incomplete karyokineses resulted in their nuclei being connected by a strand of nuclear material traversing the bridge and midbody. Such cells do not complete cytokinesis but merge together several hours after telophase. This merging of daughter cells coincides with the nearly complete breakdown of the midbody.

The Zygorhynchus zygosporangium and zygospore

1978 ◽  
Vol 56 (8) ◽  
pp. 1061-1073 ◽  
Author(s):  
K. L. O'donnell ◽  
S. L. Flegler ◽  
J. J. Ellis ◽  
C. W. Hesseltine
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Wall Layer ◽  
Primary Wall ◽  
Wall Deposition ◽  
Transmission Electron ◽  
Inner Surface

Zygosporangium and zygospore formation in Zygorhynchus was followed by scanning and transmission electron microscopy. One or more slender, lateral zygophoric filaments proliferate from the subterminal portion of a septate, erect hypha. These lateral zygophoric branches recurve and conjugate with the stout, terminal zygophoric hypha. Heteromorphic gametangia are delimited asynchronously on either side of the fusion wall. Deposition of wart material on and within the inner primary wall layer is concomitant with fusion septum dissolution. The mature zygosporangial wall is composed of electron-opaque stellate, confluent warts with an elaborate ornamented inner surface. The potential taxonomic value of mature zygosporangium and zygospore topography in Zygorhynchus is examined.

Budding patterns during the cell cycle of the maize smut pathogen Ustilago maydis

1994 ◽  
Vol 72 (11) ◽  
pp. 1675-1680 ◽  
Author(s):  
Charles W. Jacobs ◽  
Stephen J. Mattichak ◽  
James F. Knowles
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Mother Cell ◽  
Light And Electron Microscopy ◽  
Ustilago Maydis ◽  
Time Lapse ◽  
Serial Passage ◽  
Cellular Polarity ◽  
Regulatory Pathways ◽  
Bud Site

Haploid sporidia of the dimorphic phytopathogen Ustilago maydis (D.C.) Corda reproduce by budding once each cell cycle. Homogeneous log-phase sporidial cultures were generated by serial passage in liquid culture, and the growth characteristics and percentages of budded cells were determined for the cultures. The characteristics of budding were determined for individual cells by light and electron microscopy. Buds emerged only from the poles of mother cells, and cells could select either a previously used bud site, or a new bud site, each cycle. Time-lapse photomicroscopy indicated that, on solid medium, the first two buds emerged from new cells at a point distal to the site of attachment to the mother cell. In subsequent cell cycles, the buds tended to emerge from alternate poles of the mother cell. The cells used multiple bud sites at each pole. In addition, transmission and scanning electron microscopy revealed a series of annulations (bud scars) at the base of some buds, indicating that cells also used the same budding site many times. This versatility in selecting bud sites indicates that budding likely depends on complex regulatory pathways for determining cellular polarity. Key words: Ustilago maydis, bud, polarity, cell cycle, morphogenesis, yeast.

scholarly journals The absence of centrioles from spindle poles of rat kangaroo (PtK2) cells undergoing meiotic-like reduction division in vitro.

1977 ◽  
Vol 72 (2) ◽  
pp. 368-379 ◽  
Author(s):  
S Brenner ◽  
A Branch ◽  
S Meredith ◽  
M W Berns
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Time Lapse ◽  
Spindle Pole ◽  
Reduction Division ◽  
Daughter Cells ◽  
Spindle Poles ◽  
Spindle Apparatus ◽  
Time Lapse Photography

Light and electron microscopy were used to study somatic cell reduction division occurring spontaneously in tetraploid populations of rat kangaroo Potorous tridactylis (PtK2) cells in vitro. Light microscopy coupled with time-lapse photography documented the pattern of reduction division which includes an anaphase-like movement of double chromatid chromosomes to opposite spindle poles followed by the organization of two separate metaphase plates and synchronous anaphase division to form four poles and four daughter nuclei. The resulting daughter cells were isolated and cloned, showing their viability, and karyotyped to determine their ploidy. Ultrastructural analysis of cells undergoing reduction consistently revealed two duplexes of centrioles (one at each of two spindle poles) and two spindle poles in each cell that lacked centrioles but with microtubules terminating in a pericentriolar-like cloud of material. These results suggest that the centriole is not essential for spindle pole formation and division and implicate the could region as a necessary component of the spindle apparatus.

Sign in / Sign up

Export Citation Format

Share Document