Morphometric analysis of ultrastructural changes induced by Periconia circinata toxin in the outer root cap of sorghum

1983 ◽  
Vol 61 (5) ◽  
pp. 1506-1509
Author(s):  
Jonathan A. Arias ◽  
Larry D. Dunkle ◽  
Charles E. Bracker
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Morphometric Analysis ◽  
Secretory Vesicle ◽  
Root Cap ◽  
Toxic Effects ◽  
Ultrastructural Changes ◽  
Vesicle Membrane ◽  
Periconia Circinata ◽  
Resistant Genotypes

Outer root cap cells of sorghum seedlings treated with the host-specific toxin produced by Periconia circinata were analyzed morphometrically to detect changes in the quantities of cytomembranes and numbers of organelles and thus extend our observations of qualitative cytological responses to the toxin. In seedlings susceptible to the pathogen, brief (0.25 h) treatment with the toxin resulted in a marked and permanent decrease in the amounts of secretory vesicle membrane. By 2 h treatment, only secretory vesicle membrane was decreased, but longer treatments led to an increased amount of endoplasmic reticulum (4 h), which later decreased together with the amount of dictyosome membrane, while the amount of tonoplast increased (8 h). In resistant seedlings treated with the toxin, early but transient increases were detected in the quantities of plasma membrane, secretory vesicle membrane, dictyosome membrane, and endoplasmic reticulum and in the number of dictyosomes. Insensitivity to the toxin may involve the ability of resistant genotypes to recover from the toxic effects.

A Morphometric Analysis of Early Effects of Ethanol on Hepatocyte Organelles from Peromyscusmaniculatus

1998 ◽  
Vol 4 (S2) ◽  
pp. 1064-1065
Author(s):  
J. T. Ellzey ◽  
J. P. Drake ◽  
L. Dader ◽  
P. Boentges
Keyword(s):  
Endoplasmic Reticulum ◽  
South Carolina ◽  
Morphometric Analysis ◽  
Smooth Endoplasmic Reticulum ◽  
Ultrastructural Changes ◽  
Deer Mice ◽  
Pathological Changes ◽  
Genetic Stock ◽  
Early Effects ◽  
Hanta Viruses

Pathological changes of hepatocytes from rats fed a 30% ethanol-derived calories diet for three weeks include noticeable ultrastructural changes including steatosis and hypertrophy of the smooth endoplasmic reticulum. We sought to examine hepatocytes of deer mice administered ethanol in an inhalation chamber for two weeks to determine if subtle changes occur in hepatocyte organelles prior to steatosis.Two strains of Peromyscus maniculatus, ADH-positive possessing hepatic cytosolic alcohol dehydrogenase and ADH-negative deer mice lacking this enzyme were purchased from the Peromyscus Genetic Stock Center (Univ. of South Carolina). They tested negatively for Hanta viruses. A morphometric analysis of the ultrastructure of ADH+(n=14) and ADH- (n=14) controls as well as experimentals exposed to chronic, intoxicating levels of ethanol was conducted. Blood ethanol levels were maintained between 1.25-1.75 mg/ml for two weeks in the experimentals.

Ultrastructural changes in the cell surface of Coelomomyces punctatus infecting mosquito larvae

1976 ◽  
Vol 54 (13) ◽  
pp. 1419-1437 ◽  
Author(s):  
Martha J. Powell
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Granular Material ◽  
Fat Body ◽  
Vegetative Stage ◽  
Ultrastructural Changes ◽  
Anopheles Quadrimaculatus ◽  
Advanced Stages ◽  
Hyphal Bodies ◽  
Hyphal Body

As the fungus Coelomomyces punctatus develops in the coelomic cavity of the mosquito Anopheles quadrimaculatus, the conformation of the plasma membrane and extracellular coat of the fungus changes markedly. The vegetative stage was surrounded by a granular and fibrillar extracellular coat which reacted positively in the silver methenamine procedure for the localization of polysaccharides. Numerous simple, branched or contorted cytoplasmic protuberances covered the irregularly shaped hyphal bodies. The surface of the hyphal body adjacent to the fat body of the mosquito had occasional involutions of the plasma membrane sheathed by cisternae of endoplasmic reticulum. In contrast with these hyphal bodies, cytoplasmic protuberances were spaced at wide intervals along filamentous hyphae. Aborting thalli were contorted and deeply lobed. The plasma membrane was smooth, and cytoplasmic protuberances were absent on other hyphae and hyphal bodies, particularly at advanced stages of infection. Instead unattached vesicles, morphologically similar to the protuberances found on some thalli, were embedded in granular material clustered around the smooth plasma membrane of these thalli. Mosquito hemocytes appeared to engulf these vesicles and granular material. As the vegetative stage was transformed into the reproductive stage, a newly formed, compact extracellular layer surrounded the sporangial initial. Later, a darkly staining wall appeared around the resting sporangium. Cisternae of endoplasmic reticulum consistently subtended thin areas in this pitted wall.

Ultrastructural changes induced in zoospores of Lagenidium callinectes by exposure to Captan

1979 ◽  
Vol 57 (20) ◽  
pp. 2116-2121 ◽  
Author(s):  
D. G. Ruch ◽  
C. E. Bland
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Nuclear Matrix ◽  
Active Component ◽  
Marine Fungus ◽  
Toxic Action ◽  
Ultrastructural Changes ◽  
Mitochondrial Matrix ◽  
Growth Development

The effects of the fungicide Captan on growth, development, and fine structure of the marine fungus Lagenidium callinectes Couch are studied. At the minimum lethal concentration (LC100) of Captan for L. callinectes (3.2 ppm active component), zoospores exposed for 30 min failed to encyst or germinate. Ultrastructural changes caused by exposure to Captan included "washing-out" of the mitochondrial matrix and disappearance of many of the cristae, clumping of the chromatin and disappearance of the nuclear matrix, and swelling of the cisternae of the endoplasmic reticulum. Longer exposure of zoospores to Captan resulted ultimately in breakdown of the plasma membrane. These observations were in agreement with those of previous studies which indicated that the toxic action of Captan occurs primarily in mitochondria.

scholarly journals Ultrastructural Changes in the Liver of Intravenous Heroin Addicts

2010 ◽  
Vol 10 (1) ◽  
pp. 38-43 ◽  
Author(s):  
Goran Ilić ◽  
Radovan Karadžić ◽  
Lidija Kostić-Banović ◽  
Jovan Stojanović ◽  
Aleksandra Antović
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Liver Tissue ◽  
Smooth Endoplasmic Reticulum ◽  
Decisive Role ◽  
Basal Membrane ◽  
Ultrastructural Changes ◽  
Heroin Addicts ◽  
Transmission Electron ◽  
Ultrastructural Findings

The ultrastructural research has a decisive role in gathering the knowledge on the liver’s response to the influence of some drugs. The aim of the study was to perform an ultrastructurai analysis of the liver in chronic intravenous heroin addicts.The study involved the autopsy conducted on 40 bodies of intravenous heroin addicts and 10 control autopsies. The liver tissue was fixed in glutaraldehyde and moulded with epon for investigation purposes of ultrastructural changes. The analysis was performed using the method of transmission electron microscopy.In the group of intravenous heroin addicts, the liver autopsy samples showed degenerative vesicular and fat changes, chronic active and persistent hepatitis, cirrhosis, reduction in the amount of glycogen in hepatocytes, as well as the Kupffer cell’s dominant hypertrophy. Various changes occur in organelles, plasma membrane of hepatocytes and biliary channels as well as in the nucleus.The most important ultrastructural findings include: hyperplasia and hypertrophy of the smooth endoplasmic reticulum, which is histologically proven vesicular degeneration of hepatocyte occurring as a result of the increased synthesis of enzymes of smooth endoplasmic reticulum due to chronic intravenous heroin intake, and the presence of continuous basal membrane followed by transformation of the sinusoids into capillaries (in the cases of chronic active hepatitis and cirrhosis) which leads to a disorder of microcirculation and further progress of cirrhosis.

scholarly journals Complexin-2 redistributes to the membrane of muscle cells in response to insulin and contributes to GLUT4 translocation

2021 ◽  
Author(s):  
Martin Alejandro Pavarotti ◽  
Victoria Tokarz ◽  
Scott Frendo-Cumbo ◽  
Philip Bilan ◽  
Zhi Liu ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Insulin Signalling ◽  
Muscle Cells ◽  
Secretory Vesicle ◽  
Vesicle Fusion ◽  
Glut4 Translocation ◽  
Vesicle Membrane ◽  
Actin Fiber ◽  
Complexin 2 ◽  
Intracellular Compartments

Insulin stimulates glucose uptake in muscle cells by rapidly redistributing vesicles containing GLUT4 glucose transporters from intracellular compartments to the plasma membrane. GLUT4 vesicle fusion requires formation of SNARE complexes between vesicular VAMP and plasma membrane syntaxin4 and SNAP23. SNARE accessory proteins usually regulate vesicle fusion processes. Complexins aide in neuro-secretory vesicle-membrane fusion by stabilizing trans-SNARE complexes but their participation in GLUT4 vesicle fusion is unknown. We report that complexin-2 is expressed and homogeneously distributed in L6 rat skeletal muscle cells. Upon insulin stimulation, a cohort of complexin-2 redistributes to the plasma membrane. Complexin-2 knockdown markedly inhibited GLUT4 translocation without affecting proximal insulin signalling of Akt/PKB phosphorylation and actin fiber remodelling. Similarly, complexin-2 overexpression decreased maximal GLUT4 translocation suggesting that the concentration of complexin-2 is finely tuned to vesicle fusion.  These findings reveal an insulin-dependent regulation of GLUT4 insertion into the plasma membrane involving complexin-2.

Ultrastructural and developmental alterations induced by Periconia circinata toxin in the root tip of sorghum

1983 ◽  
Vol 61 (5) ◽  
pp. 1491-1505 ◽  
Author(s):  
Jonathan A. Arias ◽  
Larry D. Dunkle ◽  
Charles E. Bracker
Keyword(s):  
Endoplasmic Reticulum ◽  
Primary Root ◽  
Root Cap ◽  
Biologically Active ◽  
Root Tip ◽  
Mitochondrial Morphology ◽  
Secretory Vesicles ◽  
Secretory Product ◽  
Periconia Circinata ◽  
In Cells

Cytological and developmental effects induced by Periconia circinata toxin were examined to better understand the mechanism of action for this toxin. Roots of sorghum seedlings susceptible and resistant to P. circinata were incubated in 500 ng toxin/mL (treated) or water (controls). Root cap cells of resistant seedlings treated with the toxin were cytologically similar to those of controls, although the toxin caused a transient inhibition of mitosis in cells of the primary root tip. In outer root cap cells of susceptible seedlings treated for 0.25 h, hypersecretory activity was lost, secretory vesicles were fewer, and secretory product accumulated between the plasma membrane and cell wall. Also, inner root cap cells showed increased vacuolation. Longer treatments caused increased vacuolation, loss of starch, increased numbers of lipid bodies, pleomorphic amyloplasts, regularly stacked endoplasmic reticulum, apparent changes in the amounts of cytomembranes, dispersion of heterochromatin, and autolysis. Mitochondrial morphology was normal, but lesions in the tonoplast occurred before autolysis. The toxin also inhibited expansion and sloughing off of root cap cells and mitotic activity in the root tip. Stacked endoplasmic reticulum, nonhypersecretory dictyosomes, fewer secretory vesicles, increased vacuolation, reorganization of heterochromatin, and increased secretory product outside the protoplast were induced by P. circinata toxin and by cyanide. These data suggested that a cyanogenic compound is biologically active in cells treated with P. circinata toxin. Our results suggest that the toxin transiently affects resistant seedlings and in susceptible seedlings alters vacuolar expansion, secretory activity, and endomembrane flow, although other processes may also be affected.

Nibbling at Membranes

2013 ◽  
Vol 21 (5) ◽  
pp. 8-10
Author(s):  
Stephen W. Carmichael
Keyword(s):  
Plasma Membrane ◽  
Spatial Localization ◽  
Secretory Vesicle ◽  
Secretory Cells ◽  
Vesicle Membrane ◽  
Major Pathway ◽  
Vesicle Membranes ◽  
Strong Stimulation ◽  
Sudden Appearance ◽  
The Relationship

It has been known for decades that clathrin- and dynamin-mediated endocytosis is the major pathway for recycling the components of vesicle membranes after strong stimulation and high rates of exocytosis in secretory cells. This pathway occurs over tens of seconds to minutes after fusion of the secretory vesicle membrane with the plasma membrane. It resembles classical receptor-mediated endocytosis, but it has a trigger that is unique to secretion: the sudden appearance of the secretory vesicle membrane on the surface of the cell. However, the spatial localization, the relationship to individual fusion events, the nature of the cargo, and the timing and nature of nucleation events have been unknown. An elegant study by Mary Bittner, Rachel Aikman, and Ronald Holz has addressed these issues.

scholarly journals Secretory Vesicles Targeted to Plasma Membrane During Pollen Germination and Tube Growth

2021 ◽  
Vol 8 ◽  
Author(s):  
Huaqiang Ruan ◽  
Jiang Li ◽  
Ting Wang ◽  
Haiyun Ren
Keyword(s):  
Plasma Membrane ◽  
Pollen Tube ◽  
Pollen Germination ◽  
Higher Plants ◽  
Current Knowledge ◽  
Secretory Vesicle ◽  
Signaling Molecules ◽  
Tube Growth ◽  
Secretory Vesicles ◽  
Vesicle Membrane

Pollen germination and pollen tube growth are important biological events in the sexual reproduction of higher plants, during which a large number of vesicle trafficking and membrane fusion events occur. When secretory vesicles are transported via the F-actin network in proximity to the apex of the pollen tube, the secretory vesicles are tethered and fused to the plasma membrane by tethering factors and SNARE proteins, respectively. The coupling and uncoupling between the vesicle membrane and plasma membrane are also regulated by dynamic cytoskeleton, proteins, and signaling molecules, including small G proteins, calcium, and PIP2. In this review, we focus on the current knowledge regarding secretory vesicle delivery, tethering, and fusion during pollen germination and tube growth and summarize the progress in research on how regulators and signaling molecules participate in the above processes.

Insulin secretion by ‘kiss-and-run’ exocytosis in clonal pancreatic islet β-cells

2003 ◽  
Vol 31 (4) ◽  
pp. 833-836 ◽  
Author(s):  
T. Tsuboi ◽  
G.A. Rutter
Keyword(s):  
Plasma Membrane ◽  
Green Fluorescent Protein ◽  
Fluorescent Protein ◽  
Yellow Fluorescent Protein ◽  
Secretory Vesicle ◽  
Β Cells ◽  
Vesicle Membrane ◽  
Synaptotagmin Iv ◽  
Green Fluorescent ◽  
Kinetics Of

Exocytotic release of neuropeptides and hormones is generally believed to involve the complete merger of the secretory vesicle with the plasma membrane. However, recent data have suggested that ‘kiss-and-run’ mechanisms may also play a role. To analyse secretory events in neuroendocrine β-cells, we imaged chimaeric reporters targeted to either the vesicle membrane [chimaeras of synaptobrevin-2 and pH-sensitive green fluorescent protein (synapto·pHluorin) or of phogrin (phosphatase on the granule of insulinoma) and enhanced green fluorescent protein (EGFP) (phogrin·EGFP)] or the lumen [neuropeptide Y (NPY)·pH-insensitive yellow fluorescent protein (Venus)] by evanescent wave microscopy. Unexpectedly, the frequency of NPY·Venus release events was only 17–27% of that of vesicle fusion reported with synapto·pHluorin, but not phogrin·EGFP, indicating that exocytosis of cargo peptides that is likely to require complete collapse of the vesicle into the plasma membrane is relatively rare. However, both the frequency and the kinetics of NPY·Venus release were modulated by stimulus strength or by overexpression of synaptotagmin IV, demonstrating the plasticity of ‘kiss-and-run’ fusion.

Ultrastructural Changes Associated with Alcoholic Hyalin in Hepatocytes and Biliary Epithelial Cells

1971 ◽  
Vol 29 ◽  
pp. 572-573
Author(s):  
Odell T. Minick ◽  
Hidejiro Yokoo ◽  
Fawzia Batti
Keyword(s):  
Endoplasmic Reticulum ◽  
Epithelial Cells ◽  
Liver Biopsy ◽  
Alcoholic Hepatitis ◽  
Ultrastructural Changes ◽  
Main Mass ◽  
Biliary Epithelial Cells ◽  
Biopsy Specimens ◽  
Alcoholic Hyalin

To learn more of the nature and origin of alcoholic hyalin (AH), 15 liver biopsy specimens from patients with alcoholic hepatitis were studied in detail.AH was found not only in hepatocytes but also in ductular cells (Figs. 1 and 2), although in the latter location only rarely. The bulk of AH consisted of a randomly oriented network of closely packed filaments measuring about 150 Å in width. Bundles of filaments smaller in diameter (40-90 Å) were observed along the periphery of the main mass (Fig. 1), often surrounding it in a rim-like fashion. Fine filaments were also found close to the nucleus in both hepatocytes and biliary epithelial cells, the latter even though characteristic AH was not present (Figs. 3 and 4). Dispersed among the larger filaments were glycogen, RNA particles and profiles of endoplasmic reticulum. Dilated cisternae of endoplasmic reticulum were often conspicuous around the periphery of the AH mass. A limiting membrane was not observed.

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