Conidiogenesis in Termitaria snyderi (Fungi Imperfecti)

1973 ◽  
Vol 51 (12) ◽  
pp. 2307-2314 ◽  
Author(s):  
Saeed R. Khan ◽  
Henry C. Aldrich
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Lipid Droplets ◽  
Light And Electron Microscopy ◽  
Cross Wall ◽  
Transverse Septum ◽  
Conidiogenous Locus ◽  
Oriented Parallel ◽  
Fungi Imperfecti

Termitaria snyderi Thaxter forms small discoid lesions on the exoskeleton of different species of termites. Its conidiogenesis has been studied by light and electron microscopy. The phialides are oriented parallel in a closely packed sporodochium. The conidia are produced endogenously in basipetal succession from a fixed conidiogenous locus and are liberated when the tip is broken off the phialide as a result of the force applied by the formation of new conidia. The area of the phialide beyond the locus forms a tubular collarette. The conidium initial buds out at the locus and after it has received its organelles and reached a certain size it is delimited by a centripetally growing transverse septum. The region of the growing septum has many vesicles which may be involved in cross wall synthesis. Conidia are cylindrical, uninucleate, and double-walled. They have mitochondria, endoplasmic reticulum (ER), conspicuous lipid droplets, and vacuoles. Each conidiophore has long mitochondria, elongate nuclei, and much endoplasmic reticulum. The plasmalemma of the conidiophore is highly convoluted.

scholarly journals The Fine Structure of the Wheat Scutellum Before Germination

1972 ◽  
Vol 25 (1) ◽  
pp. 9 ◽  
Author(s):  
JG Swift ◽  
TP O'brien
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Coat Protein ◽  
Storage Protein ◽  
Cell Walls ◽  
Lipid Droplets ◽  
Light And Electron Microscopy ◽  
Ground Substance ◽  
Nuclear Chromatin

The structure of the cells of the scutellar epithelium and parenchyma is described and illustrated by light and electron microscopy of air-dry grains and compared with that seen in grains soaked for 3 hr. In the air-dry state, nuclear chromatin is strongly aggregated, mitochondria and plastids appear to be intact, endoplasmic reticulum is present but not abundant, and dictyosomes cannot be readily identified. The ground substance contains an abundance of free ribosomes which appear to coat protein bodies, lipid droplets, and mitochondria. In material soaked only for 3 hr, endoplasmic reticulum and dictyosomes are apparent, the nuclear chromatin has dispersed, and some mobilization of storage protein appears to have begun in the scutellar epithelium. No differences in fine structure of other organelles or in the cell walls could be detected.

scholarly journals STUDIES ON MICROPEROXISOMES II. A CYTOCHEMICAL METHOD FOR LIGHT AND ELECTRON MICROSCOPY

1972 ◽  
Vol 20 (12) ◽  
pp. 1006-1023 ◽  
Author(s):  
ALEX B. NOVIKOFF ◽  
PHYLLIS M. NOVIKOFF ◽  
CLEVELAND DAVIS ◽  
NELSON QUINTANA
Keyword(s):  
Endoplasmic Reticulum ◽  
Guinea Pig ◽  
Lipid Droplets ◽  
Smooth Endoplasmic Reticulum ◽  
Light And Electron Microscopy ◽  
Distal Tubule ◽  
Striking Difference ◽  
High Concentration ◽  
Electron Microscopic ◽  
Pig Kidney

A modification of the Novikoff-Goldfischer alkaline 3,3'-diaminobenzidine medium for visualizing peroxisomes is described. It makes possible light microscopic as well as electron microscopic studies of a recently described class of peroxisomes, the microperoxisomes. Potassium cyanide (5 x 10–3 M) is included in the medium to inhibit mitochondrial staining, the pH is 9.7 and there is a high concentration of H2O2 (0.05%). Two cell types have been chosen to illustrate the advantages of the new procedure for demonstrating the microperoxisomes: the absorptive cells in the human jejunum and the distal tubule cells in the guinea pig kidney. Suggestive relations of microperoxisomes and lipid are described in the human jejunum. The microperoxisomes are strategically located between smooth endoplasmic reticulum that radiates toward the organelles and contains lipid droplets and "central domains" of highly specialized endoplasmic reticulum which do not show the lipid droplets. The microperoxisomes are also present at the periphery of large lipid-like drops. In the guinea pig kidney tubule there is a striking difference between the thick limb of Henle and distal tubule. The distal tubule has a population of cells with large numbers of microperoxisomes readily visible by light microscopy; these cells are not present in the thick limb of Henle. Other differences between the two are also described.

Phase-contrast and electron-microscopic observations on a membranous complex in primary spermatocytes of the mouse

1975 ◽  
Vol 18 (1) ◽  
pp. 1-17
Author(s):  
A. Pleshkewych ◽  
L. Levine
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Phase Contrast ◽  
Cultured Cells ◽  
Light And Electron Microscopy ◽  
Cytoplasmic Inclusion ◽  
Electron Microscopic ◽  
Secondary Spermatocyte ◽  
Living Mouse ◽  
Circular Contour

A prominent cytoplasmic inclusion present in living mouse primary spermatocytes has been observed by both light and electron microscopy. It began to form at prometaphase and continued to increase in thickness and length as the cells developed. By metaphase it was a distinct sausage-shaped boundary that enclosed a portion of the cytoplasm between the spindle and the cell membrane. At the end of metaphase, the inclusion reached its maximum length. At telophase, it was divided between the daughter secondaries. The inclusion persisted as a circular contour in the interphase secondary spermatocyte. Electron microscopy of the same cultured cells that were previously observed with light microscopy revealed that the inclusion was a distinctive formation of membranes. It consisted of agranular cisternae and vesicles, and was therefore a membranous complex. Many of the smaller vesicles in the membranous complex resembled those found in the spindle. The cisternae in the membranous complex were identical to the cisternal endoplasmic reticulum of interphase primary spermatocytes. Nevertheless, the organization of vesicles and cisternae into the membranous complex was unique for the primaries in division stages, since such an organization was not present in their interphase stages.

Anatomy of the Unpollinated and Pollinated Watermelon Stigma

1982 ◽  
Vol 54 (1) ◽  
pp. 341-355
Author(s):  
M. SEDGLEY
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Light And Electron Microscopy ◽  
Freeze Fracture ◽  
Pollen Grain ◽  
Acidic Polysaccharides ◽  
Before And After ◽  
Em Autoradiography ◽  
Pollen Grain Wall ◽  
Stigma Secretion

The structure of the watermelon stigma before and after pollination was studied using light and electron microscopy, freeze-fracture and autoradiography. The wall thickenings of the papilla transfer cells contained callose and their presence prior to pollination was confirmed using EM-autoradiography, freeze-fracture and fixation. No further callose thickenings were produced following pollination. Pollination resulted in a rapid increase in aqueous stigma secretion and localized disruption of the cuticle, which appeared to remain on the surface of the secretion. Autolysis of the papilla cells, which had commenced prior to pollination, was accelerated and appeared to take place via cup-shaped vacuoles developed from distended endoplasmic reticulum. The reaction was localized to the papilla cells adjacent to the pollen tube only. Both pollen-grain wall and stigma secretion contained proteins, carbohydrates, acidic polysaccharides, lipids and phenolics.

Formation of chlamydospores in Gilbertella persicaria

1981 ◽  
Vol 59 (5) ◽  
pp. 908-928 ◽  
Author(s):  
Martha J. Powell ◽  
Charles E. Bracker ◽  
David J. Sternshein
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Acid Phosphatase ◽  
Light And Electron Microscopy ◽  
Multivesicular Bodies ◽  
Marker Enzyme ◽  
Transparent Layer ◽  
Thiamine Pyrophosphatase ◽  
Gilbertella Persicaria

The cytological events involved in the transformation of vegetative hyphae of the zygomycete Gilbertella persicaria (Eddy) Hesseltine into chlamydospores were studied with light and electron microscopy. Thirty hours after sporangiospores were inoculated into YPG broth, swellings appeared along the aseptate hyphae. Later, septa, traversed by plasmodesmata, delimited each end of the hyphal swellings and compartmentalized these hyphal regions as they differentiated into chlamydospores. Nonswollen regions adjacent to chlamydospores remained as isthmuses. Two additional wall layers appeared within the vegetative wall of the developing chlamydospores. An alveolate, electron-dense wall formed first, and then an electron-transparent layer containing concentrically oriented fibers formed between this layer and the plasma membrane. Rather than a mere condensation of cytoplasm, development and maturation of the multinucleate chlamydospores involved extensive cytoplasmic changes such as an increase in reserve products, lipid and glycogen, an increase and then disappearance of vacuoles, and the breakdown of many mitochondria. Underlying the plasma membrane during chlamydospore wall formation were endoplasmic reticulum, multivesicular bodies, vesicles with fibrillar contents, vesicles with electron-transparent contents, and cisternal rings containing the Golgi apparatus marker enzyme, thiamine pyrophosphatase. Acid phosphatase activity was localized cytochemically in a cisterna which enclosed mitochondria and in vacuoles which contained membrane fragments. Tightly packed membrane whorls and single membrane bounded sacs with finely granular matrices surrounding vacuoles were unique during chlamydospore development. Microbodies were rare in the mature chlamydospore, but endoplasmic reticulum was closely associated with lipid globules. As chlamydospores developed, the cytoplasm in the isthmus became highly vacuolated, lipid globules were closely associated with vacuoles, mitochondria were broken down in vacuoles, unusual membrane configurations appeared, and eventually the membranes degenerated. Unlike chlamydospores, walls of the isthmus did not thicken, but irregularly shaped appositions containing numerous channels formed at intervals on the inside of these walls. The pattern of cytoplasmic transformations during chlamydospore development is similar to events leading to the formation of zygospores and sporangiospores.

scholarly journals A conserved family of proteins facilitates nascent lipid droplet budding from the ER

2015 ◽  
Vol 211 (2) ◽  
pp. 261-271 ◽  
Author(s):  
Vineet Choudhary ◽  
Namrata Ojha ◽  
Andy Golden ◽  
William A. Prinz
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Lipid Metabolism ◽  
Caenorhabditis Elegans ◽  
Lipid Droplet ◽  
Lipid Droplets ◽  
De Novo ◽  
Fat Storage ◽  
Higher Eukaryotes ◽  
Er Membrane

Lipid droplets (LDs) are found in all cells and play critical roles in lipid metabolism. De novo LD biogenesis occurs in the endoplasmic reticulum (ER) but is not well understood. We imaged early stages of LD biogenesis using electron microscopy and found that nascent LDs form lens-like structures that are in the ER membrane, raising the question of how these nascent LDs bud from the ER as they grow. We found that a conserved family of proteins, fat storage-inducing transmembrane (FIT) proteins, is required for proper budding of LDs from the ER. Elimination or reduction of FIT proteins in yeast and higher eukaryotes causes LDs to remain in the ER membrane. Deletion of the single FIT protein in Caenorhabditis elegans is lethal, suggesting that LD budding is an essential process in this organism. Our findings indicated that FIT proteins are necessary to promote budding of nascent LDs from the ER.

scholarly journals LOCALIZATION OF PEROXIDASE ACTIVITY IN MICROBODIES OF FETAL MOUSE LIVER

1969 ◽  
Vol 17 (7) ◽  
pp. 454-466 ◽  
Author(s):  
EDWARD ESSNER
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Acid Phosphatase ◽  
Peroxidase Activity ◽  
Mouse Liver ◽  
Fetal Liver ◽  
Light And Electron Microscopy ◽  
Small Population ◽  
Fetal Mouse ◽  
Fetal Mouse Liver

The peroxidase activity of microbodies in fetal mouse liver was studied by light and electron microscopy. Two types of microbodies were present; a small population of bodies that lacked a nucleoid, predominant on the 16th day of gestation, and a larger population of nucleoid-bearing microbodies, predominant on the 19th day, in association with the rough endoplasmic reticulum from which they probably originate. Both types of bodies were visualized when incubated for peroxidase activity but were negative (19th day) for acid phosphatase activity. The findings suggest that the anucleoid- and nucleoid-bearing organelles together constitute the microbody population of the fetal liver.

Elektronenmikroskopische Untersuchungen über die Eizellbildung und Eizellreifung des Lebermooses Sphaerocarpus donnellii Aust.

1965 ◽  
Vol 20 (8) ◽  
pp. 795-801 ◽  
Author(s):  
Lothar Diers
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Phase Contrast ◽  
Lipid Droplets ◽  
Unit Membrane ◽  
Light Phase ◽  
Lamellar System ◽  
Small Bodies ◽  
Canal Cell ◽  
Ventral Canal

The formation and maturation of the egg of the liverwort, Sphaerocarpus donnellii, was investigated by light, phase contrast and particularly by electron microscopy. The division of the central cell into the egg and the ventral canal cell, and the maturation of the egg, is completed within four days. All stages of this formation and maturation were examined under the electron microscope after fixation in KMnO4 or OsO4. — In the maturing egg there always occur the endoplasmic reticulum, well recognisable plastids with a poorly developed lamellar system, numerous mitochondria and dictyosomes, a rising number of lipid droplets, unknown small bodies limited by a unit membrane, and numerous ribosomes. During maturation the nucleus considerably enlarges and forms evaginations into the cytoplasm. Starch is increasingly deposited in the plastids. A degeneration of plastids has not been found.

scholarly journals Studies of conidial anatomy and conidiogenesis in Sporoschisma nigroseptatum using light and electron microscopy

1998 ◽  
Vol 76 (9) ◽  
pp. 1614-1623 ◽  
Author(s):  
Wai-Hong Ho ◽  
Teik-Khiang Goh ◽  
Kevin D Hyde ◽  
I John Hodgkiss
Keyword(s):  
Electron Microscopy ◽  
Ultrastructural Study ◽  
Light And Electron Microscopy ◽  
Conidiogenous Cell ◽  
Cell Maturation ◽  
Cross Wall ◽  
Periclinal Wall

The results of an ultrastructural study of the conidial anatomy and conidiogenesis in Sporoschisma nigroseptatum are presented. The development of the conidial chain involves endogenous conidial ontogeny, apical wall-building, and retrogressive conidial delimitation followed by cessation of apical wall-building, then replacement ring wall-building of additional retrogressively delimited conidia, and extrusion of the true conidial chain through the terminal aperture of the conidiogenous cell. Maturation of conidia involves deposition of two inner wall layers and formation of five distosepta. Conidial chains secede schizolytically. No proliferation of the conidiogenous cell occurs and the conidium is delimited by a cross wall that is discontinuous with the periclinal wall. Each conidium has polar plug-and-socket-like structures that are interlocked between adjacent conidia along the conidial chain. Similar plug-and-socket-like structures are also seen in other Sporoschisma species. The taxonomy of Chalara is also briefly discussed with reference to patterns of conidial wall-building.Key words: Chalara, conidial chain, conidial ontogeny, ultrastructures.

Development of the lateral palatal brush in larvae of Aedes aegypti (L.) (Diptera: Culicidae)

1990 ◽  
Vol 68 (7) ◽  
pp. 1454-1467 ◽  
Author(s):  
K. M. Fry ◽  
S. B. McIver
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Golgi Apparatus ◽  
Aedes Aegypti ◽  
Rough Endoplasmic Reticulum ◽  
Light And Electron Microscopy ◽  
Fourth Instar ◽  
Muscle Fibres ◽  
Final Length

Light and electron microscopy were used to observe development of the lateral palatal brush in Aedes aegypti (L.) larvae. Development was sampled at 4-h intervals from second- to third-instar ecdyses. Immediately after second-instar ecdysis, the epidermis apolyses from newly deposited cuticle in the lateral palatal pennicular area to form an extensive extracellular cavity into which the fourth-instar lateral palatal brush filaments grow as cytoplasmic extensions. On reaching their final length, the filaments deposit cuticulin, inner epicuticle, and procuticle sequentially on their outer surfaces. The lateral palatal crossbars, on which the lateral palatal brush filaments insert, form after filament development is complete. At the beginning of development, the organelles involved in plasma membrane and cuticle production are located at the base and middle of the cells. As the filament rudiments grow, most rough endoplasmic reticulum, mitochondria, and Golgi apparatus move to the apex of the epidermal cells and into the filament rudiments. After formation of the lateral palatal brush filaments and lateral palatal crossbars, extensive organelle breakdown occurs. Lateral palatal brush formation is unusual in that no digestion and resorption of old endocuticle occurs prior to deposition of new cuticle. No mucopolysaccharide secretion by the lateral palatal brush epidermis was observed, nor were muscle fibres observed to attach to the lateral palatal crossbars, as has been suggested by other workers.

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