scholarly journals Effect of the venom of Glycera convoluta on the spontaneous quantal release of transmitter.

1980 ◽  
Vol 85 (2) ◽  
pp. 446-458 ◽  
Author(s):  
R Manaranche ◽  
M Thieffry ◽  
M Israel
Keyword(s):  
Electrical Activity ◽  
Morphological Changes ◽  
Electric Organ ◽  
High Rate ◽  
Ultrastructural Changes ◽  
Quantal Release ◽  
Structural Modifications ◽  
Sustained Activity ◽  
Venom Glands ◽  
Glycera Convoluta

A neurotoxin able to increase the spontaneous release of transmitter was found in the venom glands of the polychaete annelid Glycera convoluta. We studied the effect of this venom on the frog cutaneous pectoris muscle, where its application produced a prolonged (20-h), high-frequency discharge of miniature potentials. After 5 h of action, the initial store was renewed several times but no detectable ultrastructural changes were observed. After 19 h of sustained activity, nerve terminals with their normal vesicular contents were infrequent; others were fragmented and contained swollen mitochondria, abnormal inclusions, and vesicles of various sizes. In the noncholinergic crayfish neuromuscular preparation, the venom triggered an important increase in spontaneous quantal release that subsided in 1 h. An activity higher than that in resting conditions then persisted for many hours. This high electrical activity was not accompanied by any detectable structural modifications after 3 h. In the torpedo electric organ preparation, the venom elicited a burst of activity that returned to control levels in 1 h. The release of ACh (evaluated by the efflux of radioactive acetate) paralleled the high electrical activity. No morphological changes or significant depletion of tissue stores were detected. The venom of Glycera convoluta appears to enhance considerably the release of transmitter without impairing its turnover. The venom effect is Ca++ dependent and reversible by washing, at least during the first hour of action. Because the high rate of transmitter release appears dissociated from the later-occurring structural modifications, it is possible that the venom mimics one component of the double mode of action proposed for black widow spider venom.

scholarly journals Binding of a Glycera convoluta neurotoxin to cholinergic nerve terminal plasma membranes.

1983 ◽  
Vol 97 (6) ◽  
pp. 1737-1744 ◽  
Author(s):  
N Morel ◽  
M Thieffry ◽  
R Manaranche
Keyword(s):  
Nerve Terminal ◽  
Concanavalin A ◽  
Plasma Membranes ◽  
Acetylcholine Release ◽  
Motor Nerve ◽  
Biological Response ◽  
Electric Organ ◽  
Venom Glands ◽  
Torpedo Electric Organ ◽  
Glycera Convoluta

The crude extract of venom glands of the polychaete annelid Glycera convoluta triggers a large Ca2+-dependent acetylcholine release from both frog motor nerve terminals and Torpedo electric organ synaptosomes. This extract was partially purified by Concanavalin A affinity chromatography. The biological activity was correlated in both preparations to a 300,000-dalton band, as shown by gel electrophoresis. This confirmed previous determinations obtained with chromatographic methods. This glycoprotein binds to presynaptic but not postsynaptic plasma membranes isolated from Torpedo electric organ. Pretreatment of intact synaptosomes by pronase abolished both the binding and the venom-induced acetylcholine release without impairing the high K+-induced acetylcholine release. Pretreatment of nerve terminal membranes by Concanavalin A similarly prevented the binding and the biological response. Binding to Torpedo membranes was still observed in the presence of EGTA. An antiserum directed to venom glycoproteins inhibited the neurotoxin so we could directly follow its binding to the presynaptic membrane. Glycera convoluta neurotoxin has to bind to a ectocellularly oriented protein of the presynaptic terminal to induce transmitter release.

Fate of sperm membrane in fertilized ova

1993 ◽  
Vol 51 ◽  
pp. 40-41
Author(s):  
Frank J. Longo
Keyword(s):  
Electron Microscopy ◽  
Electrical Activity ◽  
Sea Urchins ◽  
Morphological Changes ◽  
Integrated System ◽  
Electrophysiological Recording ◽  
Experimental Conditions ◽  
The Status ◽  
Sperm Membrane ◽  
Temporal And Spatial

Measurement of the egg's electrical activity, the fertilization potential or the activation current (in voltage clamped eggs), provides a means of detecting the earliest perceivable response of the egg to the fertilizing sperm. By using the electrical physiological record as a “real time” indicator of the instant of electrical continuity between the gametes, eggs can be inseminated with sperm at lower, more physiological densities, thereby assuring that only one sperm interacts with the egg. Integrating techniques of intracellular electrophysiological recording, video-imaging, and electron microscopy, we are able to identify the fertilizing sperm precisely and correlate the status of gamete organelles with the first indication (fertilization potential/activation current) of the egg's response to the attached sperm. Hence, this integrated system provides improved temporal and spatial resolution of morphological changes at the site of gamete interaction, under a variety of experimental conditions. Using these integrated techniques, we have investigated when sperm-egg plasma membrane fusion occurs in sea urchins with respect to the onset of the egg's change in electrical activity.

scholarly journals Large-scale purification of presynaptic plasma membranes from Torpedo marmorata electric organ.

1985 ◽  
Vol 101 (5) ◽  
pp. 1757-1762 ◽  
Author(s):  
N Morel ◽  
J Marsal ◽  
R Manaranche ◽  
S Lazereg ◽  
J C Mazie ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Large Scale ◽  
Plasma Membranes ◽  
Electric Organ ◽  
Acetylcholinesterase Activity ◽  
Cholinergic Nerve Terminals ◽  
Membrane Bound ◽  
Torpedo Electric Organ ◽  
Presynaptic Plasma Membrane ◽  
Glycera Convoluta

The presynaptic plasma membrane (PSPM) of cholinergic nerve terminals was purified from Torpedo electric organ using a large-scale procedure. Up to 500 g of frozen electric organ were fractioned in a single run, leading to the isolation of greater than 100 mg of PSPM proteins. The purity of the fraction is similar to that of the synaptosomal plasma membrane obtained after subfractionation of Torpedo synaptosomes as judged by its membrane-bound acetylcholinesterase activity, the number of Glycera convoluta neurotoxin binding sites, and the binding of two monoclonal antibodies directed against PSPM. The specificity of these antibodies for the PSPM is demonstrated by immunofluorescence microscopy.

Ultrastructural Changes in the Surface Layers of the Newt's Egg in Relation to the Mechanism of Its Cleavage

1970 ◽  
Vol 6 (1) ◽  
pp. 207-227 ◽  
Author(s):  
G. G. SELMAN ◽  
M. M. PERRY
Keyword(s):  
Plasma Membrane ◽  
Leading Edge ◽  
Ultrastructural Changes ◽  
Cortical Layers ◽  
Active Growth ◽  
Structural Modifications ◽  
Cell Cleavage ◽  
Surface Irregularities ◽  
Dense Band ◽  
10 Nm Filaments

The surface and cortical layers of an uncleaved newt egg have a characteristic ultrastructure which remains unaltered during cleavage; ultrastructural changes are confined to the region of the furrow. At the onset of cleavage there is a dipping inwards of the rough heavily pigmented animal surface to form a groove. Along the bottom of the groove the surface irregularities are reduced and a dense band (0.1 µm thick and 16 µm wide) is formed immediately below the plasma membrane. Within this band there are parallel filaments, 8-10 nm in diameter, oriented in the direction of the future furrow. No structural modifications were observed below the cortical layers of the leading part of the furrow apart from accumulations of granules and the mid-bodies of the spindle remnant. It is proposed that the dipping-in of the groove is due to contraction within the filamentous band, rather than contraction in a sheet of subcortical gel as proposed previously. The filamentous band persists below the furrow during the later stages of cleavage. The new unpigmented surface first forms as a strip across the animal surface and begins to grow at the bottom of the groove. Over most of its area, it is much smoother than the pigmented surface and has less material on the outside of the plasma membrane. There are microvilli along the bottom of the groove. The join between the new unpigmented and the old pigmented surface is abrupt. As the new unpigmented surface grows in extent, a narrow furrow forms below the lowest part of the groove and progresses towards the vegetal surface. For most of its length the furrow is between 10-nm and 0.5 µm wide, but at its leading edge it is 2 µ wide with microvilli on its surface and 10-nm filaments below the plasma membrane. It is concluded that the progressive formation of the furrow is due to active growth of new unpigmented cell surface. At late cleavage a ridge 10 µm high forms at the join between the new and old surface. After cleavage the ridges approach and meet to form the intercellular junction by which daughter blastomeres are held together along the animal surface. The mechanism of cell cleavage in the newt egg and in other forms is discussed in the light of the present observations.

Effect of vinblastine and cytochalasin B on the cytoskeletal domains in 3T3 cells

1981 ◽  
Vol 48 (1) ◽  
pp. 55-73
Author(s):  
J.H. Temmink ◽  
H. Spiele
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Cytochalasin B ◽  
Morphological Changes ◽  
Ultrastructural Changes ◽  
3T3 Cells ◽  
Cytoplasmic Material ◽  
Transmission Electron ◽  
Cytoskeletal Elements ◽  
Scanning Electron

Normal 3T3 cells were exposed to vinblastine and cytochalasin B in an attempt to correlate the morphological changes of the cell surface as seen in the scanning electron microscope with ultrastructural changes of the cytoskeletal elements as seen in critical-point-dried cells in the transmission electron microscope. Special attention was given to the changes in the cytoplasmic domains distinguished in a previous paper. Cytochalasin B primarily affects the ultrastructure of the cytocortical domain by inducing the formation of condensation foci on the cytoplasmic material. Vinblastine not only induces the depolymerization of microtubules and the perinuclear concentration of intermediate filaments, but it also causes the disappearance of stress fibres from the cortical cytoplasm and the widening of the cytocortex at the expense of the endoplasmic domain. These results support the hypothesis that the differentiation in ultrastructural domains is dependent on the spreading of the cells and their adhesion to substrate.

scholarly journals Modulation of Metamorphic and Regenerative Events by Cold Atmospheric Pressure Plasma Exposure in Tadpoles, Xenopus laevis

2019 ◽  
Vol 9 (14) ◽  
pp. 2860 ◽  
Author(s):  
Ma Veronica Holganza ◽  
Adonis Rivie ◽  
Kevin Martus ◽  
Jaishri Menon
Keyword(s):  
Atmospheric Pressure ◽  
Developmental Plasticity ◽  
Morphological Changes ◽  
Atmospheric Pressure Plasma ◽  
Ultrastructural Changes ◽  
Plasma Exposure ◽  
Tail Regeneration ◽  
Developmental Processes ◽  
Pressure Plasma ◽  
Metamorphic Development

Atmospheric pressure plasma has found wide clinical applications including wound healing, tissue regeneration, sterilization, and cancer treatment. Here, we have investigated its effect on developmental processes like metamorphosis and tail regeneration in tadpoles. Plasma exposure hastens the process of tail regeneration but delays metamorphic development. The observed differences in these two developmental processes following plasma exposure are indicative of physiological costs associated with developmental plasticity for their survival. Ultrastructural changes in epidermis and mitochondria in response to the stress of tail amputation and plasma exposure show characteristics of cellular hypoxia and oxidative stress. Mitochondria show morphological changes such as swelling with wide and fewer cristae and seem to undergo processes such as fission and fusion. Complex interactions between calcium, peroxisomes, mitochondria and their pore transition pathways are responsible for changes in mitochondrial structure and function, suggesting the subcellular site of action of plasma in this system.

scholarly journals Light and electron microscopy characteristics of the muscle of patients with SURF1 gene mutations associated with Leigh disease

2007 ◽  
Vol 61 (4) ◽  
pp. 460-466 ◽  
Author(s):  
M Pronicki ◽  
E Matyja ◽  
D Piekutowska-Abramczuk ◽  
T Szymańska-Dębińska ◽  
A Karkucińska-Więckowska ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Lipid Accumulation ◽  
Morphological Changes ◽  
Light And Electron Microscopy ◽  
Gene Mutations ◽  
Leigh Syndrome ◽  
Typical Feature ◽  
Ultrastructural Changes ◽  
Consistent Feature ◽  
Muscle Changes

Aims:Leigh syndrome (LS) is characterised by almost identical brain changes despite considerable causal heterogeneity. SURF1 gene mutations are among the most frequent causes of LS. Although deficiency of cytochrome c oxidase (COX) is a typical feature of the muscle in SURF1-deficient LS, other abnormalities have been rarely described. The aim of the present work is to assess the skeletal muscle morphology coexisting with SURF1 mutations from our own research and in the literature.Methods:Muscle samples from 21 patients who fulfilled the criteria of LS and SURF1 mutations (14 homozygotes and 7 heterozygotes of c.841delCT) were examined by light and electron microscopy.Results:Diffuse decreased activity or total deficit of COX was revealed histochemically in all examined muscles. No ragged red fibres (RRFs) were seen. Lipid accumulation and fibre size variability were found in 14 and 9 specimens, respectively. Ultrastructural assessment showed several mitochondrial abnormalities, lipid deposits, myofibrillar disorganisation and other minor changes. In five cases no ultrastructural changes were found. Apart from slight correlation between lipid accumulation shown by histochemical and ultrastructural techniques, no other correlations were revealed between parameters investigated, especially between severity of morphological changes and the patient’s age at the biopsy.Conclusion:Histological and histochemical features of muscle of genetically homogenous SURF1-deficient LS were reproducible in detection of COX deficit. Minor muscle changes were not commonly present. Also, ultrastructural abnormalities were not a consistent feature. It should be emphasised that SURF1-deficient muscle assessed in the light and electron microscopy panel may be interpreted as normal if COX staining is not employed.

In vitrocytokines profile and ultrastructural changes of microglia and macrophages following interaction withLeishmania

Parasitology ◽  
2014 ◽  
Vol 141 (8) ◽  
pp. 1052-1063 ◽  
Author(s):  
PATRICIA KARLA SANTOS RAMOS ◽  
MAYSA DE VASCONCELOS BRITO ◽  
FERNANDO TOBIAS SILVEIRA ◽  
CLÁUDIO GUEDES SALGADO ◽  
WANDERLEY DE SOUZA ◽  
...  
Keyword(s):  
Immune Responses ◽  
Parasite Species ◽  
Morphological Changes ◽  
Expression Patterns ◽  
Ultrastructural Changes ◽  
American Cutaneous Leishmaniasis ◽  
Causative Agents ◽  
Infected Cells ◽  
Robust Response

SUMMARYIn the present study, we assessed morphological changes and cytokine production afterin vitrointeraction with causative agents of American cutaneous leishmaniasis and compared the microglia and macrophage immune responses. Cultures of microglia and macrophages infected with stationary-phase promastigotes ofLeishmania(Viannia)shawi, Leishmania(Viannia)braziliensisorLeishmania(Leishmania)amazonensiswere evaluated 24, 48 and 72 h after interaction. Macrophages only presented the classical phagocytic process while microglia also displayed large cytoplasmic projections similar to the ruffles described in macropinocytosis. In the macrophage cultures, the percentage of infected cells increased over time, in a fashion that was dependent on the parasite species. In contrast, in microglial cells as the culture time progressed, there was a significant reduction in the percentage of infected cells independent of parasite species. Measurements of cytokines in macrophage cultures 48 h after interactions revealed distinct expression patterns for different parasites, whereas in microglial cultures they were similar for allLeishmaniatested species. Taken together, our results suggest that microglia may have a higher phagocytic ability and cytotoxic potential than macrophages for all investigated species. The robust response of microglia against all parasite species may suggest microglia have an important role in the defence against cerebral leishmaniasis.

scholarly journals Triggering Apoptotic Death of Human Malignant Melanoma A375.S2 Cells by Bufalin: Involvement of Caspase Cascade-Dependent and Independent Mitochondrial Signaling Pathways

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Yu-Ping Hsiao ◽  
Chun-Shu Yu ◽  
Chien-Chih Yu ◽  
Jai-Sing Yang ◽  
Jo-Hua Chiang ◽  
...  
Keyword(s):  
Malignant Melanoma ◽  
Morphological Changes ◽  
Chromatin Condensation ◽  
Signal Pathways ◽  
Dependent Manner ◽  
S2 Cells ◽  
Concentration Dependent Manner ◽  
Human Malignant Melanoma ◽  
Intracellular Ca ◽  
Venom Glands

Bufalin was obtained from the skin and parotid venom glands of toad and has been shown to induce cytotoxic effects in various types of cancer cell lines, but there is no report to show that whether bufalin affects human skin cancer cells. The aim of this investigation was to study the effects of bufalin on human malignant melanoma A375.S2 cells and to elucidate possible mechanisms involved in induction of apoptosis. A375.S2 cells were treated with different concentrations of bufalin for a specific time period and investigated for effects on apoptotic analyses. Our results indicated that cells after exposure to bufalin significantly decreased cell viability, and induced cell morphological changes and chromatin condensation in a concentration-dependent manner. Flow cytometric assays indicated that bufalin promoted ROS productions, loss of mitochondrial membrane potential (ΔΨm), intracellular Ca2+release, and nitric oxide (NO) formations in A375.S2 cells. Additionally, the apoptotic induction of bufalin on A375.S2 cells resulted from mitochondrial dysfunction-related responses (disruption of theΔΨmand releases of cytochromec, AIF, and Endo G), and activations of caspase-3, caspase-8 and caspase-9 expressions. Based on those observations, we suggest that bufalin-triggered apoptosis in A375.S2 cells is correlated with extrinsic- and mitochondria-mediated multiple signal pathways.

The significance of morphological changes in cerebral arteries after subarachnoid hemorrhage

1990 ◽  
Vol 72 (4) ◽  
pp. 626-633 ◽  
Author(s):  
Marc R. Mayberg ◽  
Tomohisa Okada ◽  
Don H. Bark
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Whole Blood ◽  
Vessel Wall ◽  
Structural Changes ◽  
Morphological Changes ◽  
Cerebral Arteries ◽  
Cross Sectional Area ◽  
Ultrastructural Changes ◽  
Sectional Area ◽  
Cross Sectional

✓ A porcine model was developed to allow quantitative assessment of morphological changes in cerebral arteries after subarachnoid hemorrhage and to determine the significance of structural changes in producing arterial narrowing. Whole blood was selectively applied to the middle cerebral artery (MCA) of seven pigs. After 10 days, vessels were perfusion-fixed and examined by light and transmission electron microscopy and immunohistochemistry. The MCA's exposed to whole blood for 10 days showed prominent luminal narrowing associated with profound ultrastructural changes affecting all layers of the vessel wall. Morphometric analysis, however, demonstrated that significant reductions in the luminal cross-sectional area (−55.8% ± 12.5%, p < 0.005) and increases in radial wall thickness (75.1% ± 10.5%, p < 0.005) were associated with only minimal increase in the cross-sectional area of the vessel wall (12.5% ± 15%,p < 0.025). By stereological analysis, the volume density of individual components of the arterial wall was unchanged in MCA's exposed to blood. Vessels exposed to blood showed a 44% reduction in smooth-muscle cell immunoreactive actin and increased collagen in the extracellular matrix of the vessel wall. These data suggest that structural changes in cerebral arteries after subarachnoid hemorrhage do not directly contribute to vessel narrowing through increases in wall mass. Nevertheless, such changes may reflect pathological mechanisms which act to augment prolonged vasoconstriction or inhibit the maintenance of normal vascular tone.

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