Electron-dense material in the cell sall/plasma membrane interface of specialized cortical cells of peanut nodules.

AbstractPericentrin is a conserved centrosomal protein whose dysfunction has been linked to several human diseases. The precise function of Pericentrin, however, is controversial. Here, we examine Drosophila Pericentrin-like- protein (PLP) function in vivo, in tissues that form both centrosomes and cilia. PLP mutant centrioles exhibit four major defects: (1) They are too short and have subtle structural defects; (2) They separate prematurely, and so overduplicate; (3) They organise fewer MTs during interphase; (4) They fail to establish and/or maintain a proper connection to the plasma membrane— although, surprisingly, mutant centrioles can still form an axoneme and recruit transition zone (TZ) proteins. We show that PLP helps to form “ pericentriolar clouds” of electron-dense material that emanate from the central cartwheel spokes and spread outward to surround the mother centriole. The partial loss of these structures may explain the complex centriole, centrosome and cilium defects we observe in PLP mutant cells.

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Comparative Morphology of Intercellular Bridges Between Developing Germ Cells of the Ovary

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100068631 ◽

1970 ◽

Vol 28 ◽

pp. 328-329

Author(s):

J. R. Ruby ◽

R. F. Dyer ◽

R. G. Skalko ◽

R. F. Gasser ◽

E. P. Volpe

Keyword(s):

Germ Cells ◽

Rana Pipiens ◽

Comparative Morphology ◽

Dense Material ◽

Individual Species ◽

Microscope Examination ◽

Electron Dense Material ◽

Intercellular Bridges ◽

Cytoplasmic Side ◽

Intercellular Connections

An electron microscope examination of fetal ovaries has revealed that developing germ cells are connected by intercellular bridges. In this investigation several species have been studied including human, mouse, chicken, and tadpole (Rana pipiens). These studies demonstrate that intercellular connections are similar in morphology regardless of the species.Basically, all bridges are characterized by a band of electron-dense material on the cytoplasmic side of the tri-laminar membrane surrounding the connection (Fig.l). This membrane is continuous with the plasma membrane of the conjoined cells. The dense material, however, never extends beyond the limits of the bridge. Variations in the configuration of intercellular connections were noted in all ovaries studied. However, the bridges in each individual species usually exhibits one structural characteristic seldom found in the others. For example, bridges in the human ovary very often have large blebs projecting from the lateral borders whereas the sides of the connections in the mouse gonad merely demonstrate a slight convexity.

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The ultrastructure of M1-a-mediated resistance to powdery mildew infection in barley

Canadian Journal of Botany ◽

10.1139/b75-286 ◽

1975 ◽

Vol 53 (22) ◽

pp. 2589-2597 ◽

Cited By ~ 10

Author(s):

H. H. Edwards

Keyword(s):

Powdery Mildew ◽

Host Cell ◽

Electron Density ◽

Epidermal Cells ◽

Dense Material ◽

Ultrastructural Changes ◽

Electron Dense Material ◽

Host Cytoplasm ◽

Powdery Mildew Infection ◽

Cell Protoplast

M1-a-mediated resistance in barley to invasion by the CR3 race of Erysiphe graminis f. sp. hordei does not occur in every host cell with the same speed and severity. In some cells ultrastructural changes within the host cell as a result of resistance will occur within 24 h after inoculation, whereas in other cells these changes may take up to 72 h. In some cells the ultrastructural changes are so drastic that they give the appearance of a hypersensitive death of the host cell, whereas in other cells the changes are very slight. In any case, at the end of these changes the fungus ceases growth. The ultrastructural changes occur in penetrated host epidermal cells as well as non-infected adjacent epidermal and mesophyll cells.The following ultrastructural changes have been observed: (1) an electron-dense material which occurs either free in the vacuole or adhering to the tonoplast (the material is granular or in large clumps); (2) an increased electron density of the host cytoplasm and nucleus; (3) a breakdown of the tonoplast so that the cytoplasmic constituents become dispersed throughout the cell lumen; and (4) the deposition of papillar-like material in areas other than the penetration site. The first three changes take place within the host cell protoplasts and are directly attributable to the gene M1-a. These changes are typical of stress or incompatibility responses and thus M1-a appears to trigger a generalized incompatibility response in the presence of race CR3. The papillar-like material occurs outside the host cell protoplast in the same manner as the papilla and probably is not directly attributable to M1-a.

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PLASMODESMAL MODIFICATIONS AND DISTRIBUTION OF TOSPO VIRUS IN POTATO AND TOMATO

Israel Journal of Plant Sciences ◽

10.1080/07929978.1999.10676780 ◽

1999 ◽

Vol 47 (4) ◽

pp. 245-250 ◽

Cited By ~ 1

Author(s):

Ishwar D. Garg ◽

S.M. Paul Khurana

Keyword(s):

Long Distance ◽

Phloem Tissue ◽

Cortical Cells ◽

Electron Dense Material ◽

Phloem Parenchyma ◽

Long Distance Transport ◽

Infected Tomato ◽

Sieve Tubes ◽

The One ◽

Distance Transport

The tospovirus isolate on tomato was found to be systemic while the one on potato was non-systemic. The virus was present in all the tissues except xylem vessels in tomato, while it was often found only in the cortical cells of potato stems. Virions were detected in all cells of phloem tissue in tomato, while none were present in the case of potato. Plasmodesmata were present between phloem parenchyma and the phloem sieve tubes in infected tomato but none were present in infected potato. There were pronounced plasmodesmal changes in response to infection in tomato. These included dissolution of the desmotubule (central rod-like structure), making the plasmodesmata pore-like structures with a diameter of ca. 45 nm, which contained electron-dense material, presumably ribonucleoprotein of the virus. No such changes were found in infected potato. These results of comparative studies suggested that the virus was non-systemic in potato due to its non-loading into the phloem and consequently lacked long distance transport.

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Visualization of changes in ciliary tip configuration caused by sliding displacement of microtubules in macrocilia of the ctenophore Beroe

Journal of Cell Science ◽

10.1242/jcs.79.1.161 ◽

1985 ◽

Vol 79 (1) ◽

pp. 161-179 ◽

Cited By ~ 2

Author(s):

S.L. Tamm ◽

S. Tamm

Keyword(s):

Electron Microscopy ◽

Dense Material ◽

Bend Angle ◽

Two Dimensional ◽

Electron Dense Material ◽

Central Pair ◽

Rest Position ◽

Recovery Stroke ◽

Dimensional Models ◽

As If

Macrocilia from the lips of the ctenophore Beroe consist of multiple rows of ciliary axonemes surrounded by a common membrane, with a giant capping structure at the tip. The cap is formed by extensions of the A and central-pair microtubules, which are bound together by electron-dense material into a pointed projection about 1.5 micron long. The tip undergoes visible changes in configuration during the beat cycle of macrocilia. In the rest position at the end of the effective stroke (+30 degrees total bend angle), there is no displacement between the tips of the axonemes, and the capping structure points straight into the stomach cavity. In the sigmoid arrest position at the end of the recovery stroke (−60 degrees total bend angle), the tip of the macrocilium is hook-shaped and points toward the stomach in the direction of the subsequent effective stroke. This change in tip configuration is caused by sliding displacement of microtubules that are bound together at their distal ends. Electron microscopy and two-dimensional models show that the singlet microtubule cap acts as if it were hinged to the ends of the axonemes and tilted to absorb the microtubule displacement that occurs during the recovery stroke. The straight and hooked shapes of the tip are thought to help the ctenophore ingest prey.

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The apical structure in Perophora annectens (tunicate) spermatozoa: fine structure, differentiation and possible role in fertilization

Journal of Cell Science ◽

10.1242/jcs.66.1.175 ◽

1984 ◽

Vol 66 (1) ◽

pp. 175-187

Author(s):

M. Fukumoto

Keyword(s):

Fine Structure ◽

Golgi Apparatus ◽

Dense Material ◽

Electron Dense Material ◽

Extracellular Materials ◽

Small Blister

The apical structure in Perophora annectens spermatozoa is approximately 4 micron in length and it is helically coiled. Its major component is a striated structure, which may be analogous to a perforatorium. The plasmalemma enclosing the anterior quarter of the apical structure is covered by extracellular materials, the anterior ornaments. During spermiogenesis, the apical structure is first recognized as a small blister of the plasmalemma at the apex of the young spermatid. It develops into a conical protrusion and then into a finger-like process (approximately 1 micron in length). This process is transformed into an elongated process (approximately 4 micron in length) with electron-dense material in its core. Finally, the elongated process is helically coiled to form an apical structure in which electron-dense material forms dense striations. Vesicles (50-70 nm in diameter), presumably derived from the Golgi apparatus, have been recognized in the blisters of younger spermatids, and can be followed through to the finger-like process. In the finger-like process these vesicles are transformed into smaller vesicles (20-30 nm in diameter), which probably fuse with the anterior plasmalemma of the finger-like process. This suggests that chorion lysin(s) is associated with the anterior membrane enclosing the apical structure in these spermatozoa.

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Ultrastructural studies on the development and form of the principal piece sheath of the bandicoot spermatozoon

Australian Journal of Zoology ◽

10.1071/zo9700021 ◽

1970 ◽

Vol 18 (1) ◽

pp. 21 ◽

Cited By ~ 11

Author(s):

CS Sapsford ◽

CA Rae ◽

KW Cleland

Keyword(s):

Plasma Membrane ◽

Dense Material ◽

Axial Filament ◽

Ultrastructural Studies ◽

The Future ◽

Membrane Bound ◽

End To End ◽

Principal Piece

The first components of the sheath to develop are two longitudinal columns, characterized by alternating light and dark bands. The columns, which lie on opposite sides of the future principal piece, are initially associated with the axial filament complex but soon make contact with the plasma membrane. Subsequently a layer of moderately dense material grows outwards from the lateral aspects of each column. The outgrowths lie just beneath the tail plasma membrane and contain evenly spaced filaments which are connected with the dark bands of the columns. The outgrowths from corresponding sides of each column eventually meet each other and the filaments they contain join end-to-end. Some parts of the sheath, separated from the plasma membrane by an expansion of the cytoplasm of the intraspermatid tail, become invested by membrane bound vacuoles. The filaments form into groups, and filaments within groups converge to produce the anlagen of the ribs of the mature sheath. The filaments lose their identity in these anlagen, which, like the columns, develop much finer filamentous structures. The ribs, and subsequently the columns, lose contact with the tail plasma membrane. The mature sheath, the ultrastructure of which is described in detail, is developed by further modification of the rib anlagen and longitudinal columns.

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Distribution of membrane cholesterol of adrenal cortical cells after corticotropin stimulation

Biochemical Journal ◽

10.1042/bj2140561 ◽

1983 ◽

Vol 214 (2) ◽

pp. 561-567 ◽

Cited By ~ 2

Author(s):

O M Conneely ◽

J M Greene ◽

D R Headon ◽

J Hsiao ◽

F Ungar

Keyword(s):

Plasma Membrane ◽

Cholesteryl Ester ◽

Membrane Cholesterol ◽

Cortical Cells ◽

Cholesterol Levels ◽

Adrenal Cortical Cells ◽

Hydrolysis Of ◽

Plasma Membrane Cholesterol ◽

Corticotropin Stimulation ◽

Stimulation Of

Membrane cholesterol in adrenal cortical cells is enriched in the plasma membrane. Stimulation of isolated adrenal cortical cells with corticotropin leads to the production of corticosterone. At high levels of corticotropin, cholesterol for corticosterone synthesis arises by hydrolysis of cellular cholesteryl ester, whereas at lower levels of corticotropin cholesteryl ester levels are unchanged from control values and there is a decrease in plasma-membrane cholesterol levels.

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Origine et formation de différents types de vacuoles induites par la multiplication d'Alphavirus Sindbis dans divers systemes cellulaires

Canadian Journal of Microbiology ◽

10.1139/m79-225 ◽

1979 ◽

Vol 25 (12) ◽

pp. 1452-1459 ◽

Cited By ~ 1

Author(s):

Yves Lombard ◽

Philippe Poindron ◽

Aimé Porte

Keyword(s):

Endoplasmic Reticulum ◽

Glial Cells ◽

Chicken Embryo ◽

Cytoplasmic Membrane ◽

Dense Material ◽

Newborn Mice ◽

Electron Dense Material ◽

Double Membrane ◽

Single Membrane ◽

Chicken Embryo Fibroblasts

Spherule-containing vacuoles and nucleocapsid-bearing vacuoles (cytopathic vacuoles types 1 and 2 respectively of Grimley et al. 1968) induced by Alphavirus Sindbis were studied in brains from newborn mice, chicken embryo fibroblasts, and two lines of tumoral glial cells from muridae. Endoplasmic reticulum (ER) elements and finely granular electron-dense material also seen in contact with nucleocapsids seemed to be involved in the formation of the classical single-membrane spherule-containing vacuoles. A second type of spherule-containing vacuoles were characterized by their double membrane and an amorphous electron-dense content and were probably derived from mitochondria. Nucleocapsid-bearing vacuoles were formed from modified ER elements and seemed to be linked to excessive synthesis of viral material. Such ER alterations were not observed in RG6 cells. In these cells, there were only spherule-containing vacuoles, while nucleocapsids were seen associated with the cytoplasmic membrane only.

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The genetics, ultrastructure, and tubulin polypeptides of mebendazole-resistant mutants of Caenorhabditis elegans

Canadian Journal of Zoology ◽

10.1139/z89-343 ◽

1989 ◽

Vol 67 (10) ◽

pp. 2422-2431 ◽

Cited By ~ 5

Author(s):

Robin A. Woods ◽

Kathleen M. B. Malone ◽

Andrew M. Spence ◽

Wade J. Sigurdson ◽

Edward H. Byard

Keyword(s):

Caenorhabditis Elegans ◽

Dense Material ◽

Autosomal Gene ◽

Wild Type ◽

Electron Dense Material ◽

C Elegans ◽

Accessory Cells ◽

Ethylmethane Sulphonate ◽

Resistant Mutants ◽

Β Tubulin

Mebendazole-resistant mutants of Caenorhabditis elegans were isolated following mutagenesis of the wild-type strain, N2, with ethylmethane sulphonate. The mutants define a single autosomal gene and are allelic to ben-1. They grow, move, and reproduce normally in the presence of mebendazole and are cross-resistant to albendazole, cambendazole, fenbendazole, methylbenzimidazole carbamate, and thiabendazole. Accumulations of membrane-bound, electron-dense material associated with the nervous tissue and associated cells are seen in electron micrographs of L3, L4, and adult stages of N2 grown in the presence of mebendazole, but are not found in the mutants. The electron-dense material appears to be associated with the accessory cells of the neuropil rather than with the neurons. The tubulins from wild type, N2, and the mutants were characterised by two-dimensional electrophoresis followed by silver staining and Western blotting with monoclonal antibodies to α- and β-tubulin. A single isotype of α-tubulin is apparent in both N2 and the mutants. One major and three minor β-tubulin isotypes, bt-1 to bt-3, can be discerned in N2; the minor isotype bt-2 is absent in all the mutants. These findings suggest that the isotype bt-2 is the primary site of action of benzimidazole-based drugs in C. elegans.

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