Signal-induced reorganization of the microtubular cytoskeleton in the ciliated protozoon Euplotes octocarinatus

1987 ◽  
Vol 87 (4) ◽  
pp. 555-564
Author(s):  
MARIA JERKA-DZIADOSZ ◽  
CHRISTINE DOSCHE ◽  
HANS-WERNER KUHLMANN ◽  
KLAUS HECKMANN
Keyword(s):  
General Pattern ◽  
Dorsal Surface ◽  
Cell Cortex ◽  
Circular Form ◽  
Transmission Electron ◽  
Microtubular Cytoskeleton ◽  
Subcortical Regions ◽  
Cell Changes ◽  
Euplotes Octocarinatus ◽  
Triton X

A predator-released substance induces the freshwater ciliate Euplotes octocarinatus to undergo, within a few hours, a drastic change in cell form that makes engulfment by the predator more difficult or even impossible. During this transformation, the outline of the cell changes from ovoid to circular and the size increases considerably. The cells cease dividing while they transform, but later continue divisional morphogenesis and maintain the circular form for many cell generations if the concentration of the predator factor is maintained. The microtubular cytoskeleton of Euplotes was studied by transmission electron microscopy of cells from which the cytoplasm had been extracted by mild treatment with Triton X-100. This procedure increased the visibility of microtubules, especially single microtubules located in the endoplasm. In transformed cells, a considerable increase in number of microtubular triads on the dorsal and ventral surfaces and the appearance of extra single microtubules between the dorsal triads was observed. However, certain interconnected groupings of microtubules located on the dorsal surface were greatly diminished after transformation. Intracytoplasmic microtubules were also more abundant in the enlarged cells than in the untreated ovoid ones. The spacing and general pattern of microtubules, however, appears to be the same in untreated and treated cells. We conclude from these observations that the transformation of Euplotes cells from their typical ovoid form into the enlarged circular form is accompanied by the mobilization and utilization of microtubules already present in subcortical regions and an assembly of new microtubules needed for support of the expanding cell cortex.

scholarly journals Epithelial structure revealed by chemical dissection and unembedded electron microscopy.

1984 ◽  
Vol 99 (1) ◽  
pp. 203s-208s ◽  
Author(s):  
E G Fey ◽  
D G Capco ◽  
G Krochmalnic ◽  
S Penman
Keyword(s):  
Nuclear Matrix ◽  
Intermediate Filament ◽  
Protein Composition ◽  
Intact Cells ◽  
Thin Sections ◽  
Transmission Electron ◽  
Kidney Epithelial Cell ◽  
Epithelial Structure ◽  
Triton X ◽  
Whole Mounts

Cytoskeletal structures obtained after extraction of Madin-Darby canine kidney epithelial cell monolayers with Triton X-100 were examined in transmission electron micrographs of cell whole mounts and unembedded thick sections. The cytoskeleton, an ordered structure consisting of a peripheral plasma lamina, a complex network of filaments, and chromatin-containing nuclei, was revealed after extraction of intact cells with a nearly physiological buffer containing Triton X-100. The cytoskeleton was further fractionated by extraction with (NH4)2SO4, which left a structure enriched in intermediate filaments and desmosomes around the nuclei. A further digestion with nuclease and elution with (NH4)2SO4 removed the chromatin. The stable structure that remained after this procedure retained much of the epithelial morphology and contained essentially all of the cytokeratin filaments and desmosomes and the chromatin-depleted nuclear matrices. This structural network may serve as a scaffold for epithelial organization. The cytoskeleton and the underlying nuclear matrix intermediate filament scaffold, when examined in both conventional embedded thin sections and in unembedded whole mounts and thick sections, showed the retention of many of the detailed morphological aspects of the intact cells, which suggests a structural continuum linking the nuclear matrix, the intermediate filament network, and the intercellular desmosomal junctions. Most importantly, the protein composition of each of the four fractions obtained by this sequential procedure was essentially unique. Thus, the proteins constituting the soluble fraction, the cytoskeleton, the chromatin fraction, and the underlying nuclear matrix-intermediate filament scaffold are biochemically distinct.

scholarly journals Adhesion of cells to surfaces coated with polylysine. Applications to electron microscopy.

1975 ◽  
Vol 66 (1) ◽  
pp. 198-200 ◽  
Author(s):  
D Mazia ◽  
G Schatten ◽  
W Sale
Keyword(s):  
Electron Microscopy ◽  
Sea Urchin ◽  
Mammalian Cells ◽  
Experimental Treatment ◽  
The Body ◽  
Transmission Electron ◽  
Coated Plate ◽  
Living Material ◽  
Coated Surfaces ◽  
Triton X

Cells of many kinds adhere firmly to glass or plastic surfaces which have been pretreated with polylysine. The attachment takes place as soon as the cells make contact with the surfaces, and the flattening of the cells against the surfaces is quite rapid. Cells which do not normally adhere to solid surfaces, such as sea urchin eggs, attach as well as cells which normally do so, such as amebas or mammalian cells in culture. The adhesion is interpreted simply as the interaction between the polyanionic cell surfaces and the polycationic layer of adsorbed polylysine. The attachment of cells to the polylysine-treated surfaces can be exploited for a variety of experimental manipulations. In the preparation of samples for scanning or transmission electron microscopy, the living material may first be attached to a polylysine-coated plate or grid, subjected to some experimental treatment (fertilization of an egg, for example), then transferred rapidly to fixative and further passed through processing for observation; each step involves only the transfer of the plate or grid from one container to the next. The cells are not detached. The adhesion of the cell may be so firm that the body of the cell may be sheared away, leaving attached a patch of cell surface, face up, for observation of its inner aspect. For example, one may observe secretory vesicles on the inner face of the surface (3) or may study the association of filaments with the inner surface (Fig. 1). Subcellular structures may attach to the polylysine-coated surfaces. So far, we have found this to be the case for nuclei isolated from sea urchin embryos and for the microtubules of flagella, which are well displayed after the membrane has been disrupted by Triton X-100 (Fig. 2).

scholarly journals Giardia muris and Giardia duodenalis groups: ultrastructural differences between the trophozoites

1989 ◽  
Vol 31 (4) ◽  
pp. 242-247 ◽  
Author(s):  
Maria Inês L. Sogayar ◽  
Elisa Aparecida Gregório
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Giardia Duodenalis ◽  
Dorsal Surface ◽  
Distal Extremity ◽  
Transmission Electron ◽  
Marginal Plate ◽  
Marginal Plates ◽  
Giardia Muris ◽  
Rats And Mice

Trophozoites of the Giardia muris group from hamsters, domestic rats and mice and of the Giardia duodenalis group from hamsters and domestic rats were examined by transmission electron microscopy. The basic ultrastructure of the trophozoites was similar. Differences were shown in the morphology of the ventrolateral flange of the trophozoites of Giardia muris and Giardia duodenalis groups. Marginal plates are less developed in the species of the Giardia duodenalis group. In this group, the distal extremity of the lateral flange is short and thick and the marginal plate does not penetrate into the distal extremity of the flange. In the Giardia muris group, the ventro-lateral flange is well developed and narrow and the marginal plate penetrates the distal extremity of the flange. The osmiophilic lamella, which accompanies the dorsal surface of the marginal plate is seen only in the Giardia muris group.

scholarly journals The Antibacterial Assay of Tectorigenin with Detergents or ATPase Inhibitors against Methicillin-ResistantStaphylococcus aureus

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Dae-Ki Joung ◽  
Su-Hyun Mun ◽  
Kuang-Shim Lee ◽  
Ok-Hwa Kang ◽  
Jang-Gi Choi ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Biological Activities ◽  
Wide Spectrum ◽  
Multidrug Resistant ◽  
Transmission Electron ◽  
Antibacterial Assay ◽  
Atpase Inhibitors ◽  
Resistant Strains ◽  
Activity Mechanism ◽  
Triton X

Tectorigenin (TTR) is an O-methylated isoflavone derived from the rhizome ofBelamacanda chinensis(L.) DC. It is known to perform a wide spectrum of biological activities such as antioxidant, anti-inflammatory, anti-tumor. The aim of this study is to examine the mechanism of antibacterial activity of TTR against methicillin-resistantStaphylococcus aureus(MRSA). The anti-MRSA activity of TTR was analyzed in combination assays with detergent, ATPase inhibitors, and peptidoglycan (PGN) derived fromS. aureus. Transmission electron microscopy (TEM) was used to monitor survival characteristics and changes inS. aureusmorphology. The MIC values of TTR against all the tested strains were 125 μg/mL. The OD(600) of each suspension treated with a combination of Triton X-100, DCCD, and NaN3with TTR (1/10 × MIC) had been reduced from 68% to 80%, compared to the TTR alone. At a concentration of 125 μg/mL, PGN blocked antibacterial activity of TTR. This study indicates that anti-MRSA action of TTR is closely related to cytoplasmic membrane permeability and ABC transporter, and PGN at 125 μg/mL directly bind to and inhibit TTR at 62.5 μg/mL. These results can be important indication in study on antimicrobial activity mechanism against multidrug resistant strains.

scholarly journals Mild Hydrothermal Synthesis of Ni–Cu Nanoparticles

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
G. H. Mohamed Saeed ◽  
S. Radiman ◽  
S. S. Gasaymeh ◽  
H. N. Lim ◽  
N. M. Huang
Keyword(s):  
Sodium Dodecyl ◽  
Hydrothermal Condition ◽  
Average Particle ◽  
Particle Sizes ◽  
Cu Nanoparticles ◽  
Cu Alloy ◽  
Transmission Electron ◽  
Metal Metal ◽  
Paramagnetic Behaviour ◽  
Triton X

Magnetic Ni-rich Ni–Cu nanoparticles with Ni : Cu mass ratio (S) of 2.0 and 2.6 were prepared using a mixture of polyoxyethylene (10) isooctylphenyl ether (Triton X-100) and sodium dodecyl sulfate (SDS) in a mild hydrothermal condition at 95ºC. X-ray diffractometry (XRD) showed that the nanoparticles prepared atS=2.0possessed Ni–Cu alloy characteristic whereas the characteristic was absent atS=2.6. The XRD data was enhanced by Fourier transform infrared spectroscopy (FTIR) which exhibited metal-metal (Ni–Cu) band at 455 cm−1. Based on transmission electron microscopy (TEM), the average particle sizes for the nanoparticles prepared atS=2.0and 2.6 were in the range of 19–23 nm. The as-prepared nanoparticles exhibited paramagnetic behaviour measured using a vibrating sample magnetometer (VSM) and the specific saturation magnetization decreased at the higher concentration of Ni.

scholarly journals Midsagittal Brain Variation among Non-Human Primates: Insights into Evolutionary Expansion of the Human Precuneus

2017 ◽  
Vol 90 (3) ◽  
pp. 255-263 ◽  
Author(s):  
Ana Sofia Pereira-Pedro ◽  
James K. Rilling ◽  
Xu Chen ◽  
Todd M. Preuss ◽  
Emiliano Bruner
Keyword(s):  
Homo Sapiens ◽  
Brain Size ◽  
Anatomical Variation ◽  
General Pattern ◽  
Dorsal Surface ◽  
Modern Human ◽  
Brain Morphology ◽  
Functional Region ◽  
Medial Side ◽  
Species Specific

The precuneus is a major element of the superior parietal lobule, positioned on the medial side of the hemisphere and reaching the dorsal surface of the brain. It is a crucial functional region for visuospatial integration, visual imagery, and body coordination. Previously, we argued that the precuneus expanded in recent human evolution, based on a combination of paleontological, comparative, and intraspecific evidence from fossil and modern human endocasts as well as from human and chimpanzee brains. The longitudinal proportions of this region are a major source of anatomical variation among adult humans and, being much larger in Homo sapiens, is the main characteristic differentiating human midsagittal brain morphology from that of our closest living primate relative, the chimpanzee. In the current shape analysis, we examine precuneus variation in non-human primates through landmark-based models, to evaluate the general pattern of variability in non-human primates, and to test whether precuneus proportions are influenced by allometric effects of brain size. Results show that precuneus proportions do not covary with brain size, and that the main difference between monkeys and apes involves a vertical expansion of the frontal and occipital regions in apes. Such differences might reflect differences in brain proportions or differences in cranial architecture. In this sample, precuneus variation is apparently not influenced by phylogenetic or allometric factors, but does vary consistently within species, at least in chimpanzees and macaques. This result further supports the hypothesis that precuneus expansion in modern humans is not merely a consequence of increasing brain size or of allometric scaling, but rather represents a species-specific morphological change in our lineage.

Inhibitory Effect of Hydroxyapatite Nanoparticles on K562 Cells

2011 ◽  
Vol 685 ◽  
pp. 352-356 ◽  
Author(s):  
Hong Lian Dai ◽  
Pei Chen ◽  
Yin Chao Han ◽  
Xin Yu Wang ◽  
Shi Pu Li
Keyword(s):  
Myeloid Leukemia ◽  
K562 Cells ◽  
Inhibitory Effect ◽  
Inhibition Mechanism ◽  
Hydroxyapatite Nanoparticles ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Cell Changes ◽  
Crystallization Degree

HAP Nanoparticles Was Synthesized by Homogeneous Precipitation. the Size Distribution, Crystallization Degree and Morphology of the Precipitation Were Characterized by Laser Granularity Instrument, X-Ray Diffraction (XRD), and Transmission Electron Microscope (TEM) Respectively. the Prepared HAP Nanoparticles Were Used for the Treatment of Human Chronic Myeloid Leukemia K562 Cells. the Inhibition Effect of the Nanoparticles on the Proliferation of K562 Cells Was Measured by MTT Assay and Growth Curve Test. the Results Showed that the HAP Nanoparticles Inhibit the Proliferation of K562 Cells Dramatically in Vitro. the Likely Inhibition Mechanism of HAP Nanoparticles on the K562 Cells Is that the Nanoparticles Entered into the Dells, Induced a Series of Cell Changes, through Cell Death of Apoptosis, Oncosis and Autoschizis, Thus Led to the Death of K562 Cells.

scholarly journals Isolation and electrophoretic analysis of nucleoli, phenol-soluble nuclear proteins, and outer cyst walls from Acanthamoeba castellanii during encystation initiation.

1976 ◽  
Vol 68 (3) ◽  
pp. 740-751 ◽  
Author(s):  
R W Rubin ◽  
M C Hill ◽  
P Hepworth ◽  
J Boehmer
Keyword(s):  
Gel Electrophoresis ◽  
Acanthamoeba Castellanii ◽  
Electrophoretic Analysis ◽  
Growth Cycle ◽  
Nuclear Proteins ◽  
Whole Cells ◽  
Nucleolar Proteins ◽  
Transmission Electron ◽  
Identical Manner ◽  
Triton X

A technique is described for isolating nuceoli from Acanthamoeba castellanii. Nuclei isolated by a modification of the technique of F. J. Chlapowski and R. N. Band (1971) are sonicated in a surcrose-Tris-MgSO4-KC1-Triton X-100 buffer and centrifuged on a linear sucrose gradient extending from 1.3 M to 1.5 M with a 2.6 M cushion, at 41000 rpm for 90 min. The only apparent contaminants in the nucleolar preparation are outer cyst walls. A procedure is described for the isolation of chemically pure outer cyst walls, and a comparison of the proteins with the nucleolar preparation reveals that outer cyst walls represent negligible contaminants. The ultrastructure of these isolated nucleoli examined with transmission electron microscopy is found to be identical with that of nucleoli from whole cells, fixed in an identical manner. The 50 nucleolar proteins separated by SDS gel electrophoresis have been examined throughout the growth cycle of Acanthamoeba and into the strat of induced encystment, at which time 10 protein bands disappear, 11 bands are observed to decrease, and 8 are seen to increase in concentration. Phenol-soluble proteins are extracted from the nucleolus which correspond to 29 of the 50 nucleolar proteins, with 17 of these proteins corresponding to nucleolar proteins that change at the onset of encystment. Thes nucleolar proteins are also compared with those of rat liver nucleoli by gel electrophoresis, resulting in the observation that extremely few protein homologies exist between the two. Numerous quantitative and qualitative changes in the gel pattern of phenol-soluble nuclear proteins during early and late log phase growth and the onset of stationary phase were also observed.

scholarly journals Observations of the marginal band system of nucleated erythrocytes.

1978 ◽  
Vol 78 (1) ◽  
pp. 260-273 ◽  
Author(s):  
W D Cohen
Keyword(s):  
Phase Contrast ◽  
Band System ◽  
Proteolytic Enzymes ◽  
Mirror Image ◽  
Structural Components ◽  
Microtubule Polymerization ◽  
Transmission Electron ◽  
Marginal Band ◽  
Triton X

The marginal band (MB) of nucleated erythrocytes (thos of nonmammalian vertebrates) is a continuous peripheral bundle of microtubules normally obscured by hemoglobin. Treatment of these elliptical cells with modified microtubule polymerization media containing Triton X-100 yields a semilysed system in which MB, nucleus, and trans-MB material (TBM) are visible under phase contrast. The TBM apparently interconnects structural components, passing around opposite sides of the nucleus and suspending it in native position. In uranyl acetatestained whole whole mounts (goldfish) examined by transmission electron microscopy, the TBM appears as a network. MBs of semilysed cells are relatively planar initially, but twist subsequently into a range of "figure-8" shapes with one of the two possible mirror-image configurations predominant. Nuclei and MBs can be released using proteolytic enzymes, to which the TBM seems most rapidly vulnerable. MBs thus freed are birefringent, generally untwisted, and much more circular than they are in situ. As a working hypothesis, it is prosposed that the flattened, elliptical shape of nucleated erythrocytes is a result of TBM tension applied asymmetrically across an otherwise more circular MB, and that the firure-8 configuration occurs when there is extreme TBM shrinkage or contraction.

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