scholarly journals Luminal particles within cellular microtubules

2006 ◽  
Vol 174 (6) ◽  
pp. 759-765 ◽  
Author(s):  
Boyan K. Garvalov ◽  
Benoît Zuber ◽  
Cédric Bouchet-Marquis ◽  
Mikhail Kudryashev ◽  
Manuela Gruska ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Cross Sectional ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
Quantitative Manner ◽  
Internal Side ◽  
20 Nm ◽  
Cellular Components

The regulation of microtubule dynamics is attributed to microtubule-associated proteins that bind to the microtubule outer surface, but little is known about cellular components that may associate with the internal side of microtubules. We used cryoelectron tomography to investigate in a quantitative manner the three dimensional structure of microtubules in intact mammalian cells. We show that the lumen of microtubules in this native state is filled with discrete, globular particles with a diameter of 7 nm and spacings between 8 and 20 nm in neuronal cells. Cross-sectional views of microtubules confirm the presence of luminal material in vitreous sections of brain tissue. Most of the luminal particles had connections to the microtubule wall, as revealed in tomograms. A higher accumulation of particles was seen near the retracting plus ends of microtubules. The luminal particles were abundant in neurons, but were also observed in other cells, such as astrocytes and stem cells.

Three Dimensional Reconstruction of Map-Free Tubulin Sheets

1982 ◽  
Vol 40 ◽  
pp. 88-89
Author(s):  
T.A. Ceskaa ◽  
B. McEwena ◽  
S.J. Edelsteina
Keyword(s):  
Three Dimensional ◽  
Real Space ◽  
Dimensional Structure ◽  
Dimensional Representation ◽  
Space Correlation ◽  
Microtubule Associated Proteins ◽  
Three Dimensional Representation ◽  
Dimensional Reconstruction ◽  
Associated Proteins ◽  
Correlation Techniques

The three-dimensional structure of zinc-induced tubulin sheets freed from microtubule associated proteins (MAPs) has been reconstructed from a series of electron micrographs of negatively stained specimens at various tilt angles. Digitized images of these sheets were analyzed by computer using a combination of real space correlation techniques and Fourier analysis to obtain a three-dimensional representation of the structure.

scholarly journals Automated S/TEM Sample Preparation for Semiconductor Process Support

2007 ◽  
Vol 15 (1) ◽  
pp. 26-29
Author(s):  
Greg Cuti ◽  
Taha Jabbar
Keyword(s):  
Semiconductor Industry ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Cross Sectional ◽  
Critical Dimensions ◽  
Manufacturing Operations ◽  
Process Support ◽  
Scanning Transmission ◽  
Cross Sectional Imaging ◽  
20 Nm

The semiconductor industry has unquestionably entered the realm of nanotechnology. Critical dimensions of many features are specified in nanometers. Gate oxides are only a few nanometers thick. Barrier and seed layers for copper processes are not much more. Gate lengths are forecast at less than 20 nm by the end of the decade. Additionally, the drive to increase device density is leading to the adoption of FinFET and other new transistor designs that include complex three-dimensional structure. Even conventional planar CMOS designs now incorporate processes such as damascene interconnects that are inherently three dimensional. The combined need for higher spatial resolution and cross-sectional imaging of complex structures has led to a significant increase in the demand for scanning transmission electron microscopy (STEM) and (TEM) in semiconductor manufacturing operations.

Mitochondrial Reconstructions Based on Serial Thick Sections and HVEM

1975 ◽  
Vol 33 ◽  
pp. 286-287
Author(s):  
Jerome J. Paulin
Keyword(s):  
Imaging Techniques ◽  
Three Dimensional ◽  
Posterior Pole ◽  
Dimensional Structure ◽  
Stereo Imaging ◽  
Thin Sections ◽  
Anatomical Features ◽  
The Past ◽  
Cellular Components ◽  
Mitochondrial Reticulum

Within the past decade it has become apparent that HVEM offers the biologist a means to explore the three-dimensional structure of cells and/or organelles. Stereo-imaging of thick sections (e.g. 0.25-10 μm) not only reveals anatomical features of cellular components, but also reduces errors of interpretation associated with overlap of structures seen in thick sections. Concomitant with stereo-imaging techniques conventional serial Sectioning methods developed with thin sections have been adopted to serial thick sections (≥ 0.25 μm). Three-dimensional reconstructions of the chondriome of several species of trypanosomatid flagellates have been made from tracings of mitochondrial profiles on cellulose acetate sheets. The sheets are flooded with acetone, gluing them together, and the model sawed from the composite and redrawn.The extensive mitochondrial reticulum can be seen in consecutive thick sections of (0.25 μm thick) Crithidia fasciculata (Figs. 1-2). Profiles of the mitochondrion are distinguishable from the anterior apex of the cell (small arrow, Fig. 1) to the posterior pole (small arrow, Fig. 2).

scholarly journals Scanning Electron-Assisted Dielectric Microscopy Reveals Autophagosome Formation by LC3 and ATG12 in Cultured Mammalian Cells

2021 ◽  
Vol 22 (4) ◽  
pp. 1834
Author(s):  
Tomoko Okada ◽  
Toshihiko Ogura
Keyword(s):  
Mammalian Cells ◽  
Culture Medium ◽  
Related Gene ◽  
Autophagosome Formation ◽  
Intact Cells ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
The Difference ◽  
Related Proteins ◽  
Scanning Electron

Autophagy is an intracellular self-devouring system that plays a central role in cellular recycling. The formation of functional autophagosomes depends on several autophagy-related proteins, including the microtubule-associated proteins 1A/1B light chain 3 (LC3) and the conserved autophagy-related gene 12 (Atg12). We have recently developed a novel scanning electron-assisted dielectric microscope (SE-ADM) for nanoscale observations of intact cells. Here, we used the SE-ADM system to observe LC3- and Atg12-containing autophagosomes in cells labelled in the culture medium with antibodies conjugated to colloidal gold particles. We observed that, during autophagosome formation, Atg12 localized along the actin meshwork structure, whereas LC3 formed arcuate or circular alignments. Our system also showed a difference in the distribution of LC3 and Atg12; Atg12 was broadly distributed while LC3 was more localized. The difference in the spatial distribution demonstrated by our system explains the difference in the size of fluorescent spots due to the fluorescently labelled antibodies observed using optical microscopy. The direct SE-ADM observation of cells should thus be effective in analyses of autophagosome formation.

Function and three-dimensional structure of intervessel pit membranes in angiosperms: a review

IAWA Journal ◽  
2019 ◽  
Vol 40 (4) ◽  
pp. 673-702 ◽  
Author(s):  
Lucian Kaack ◽  
Clemens M. Altaner ◽  
Cora Carmesin ◽  
Ana Diaz ◽  
Mirko Holler ◽  
...  
Keyword(s):  
Water Transport ◽  
Three Dimensional ◽  
Cellulose Microfibrils ◽  
Dimensional Structure ◽  
High Porosity ◽  
Dynamic Surface ◽  
Three Dimensional Structure ◽  
Pit Membrane ◽  
Bordered Pits ◽  
20 Nm

ABSTRACTPit membranes in bordered pits of tracheary elements of angiosperm xylem represent primary cell walls that undergo structural and chemical modifications, not only during cell death but also during and after their role as safety valves for water transport between conduits. Cellulose microfibrils, which are typically grouped in aggregates with a diameter between 20 to 30 nm, make up their main component. While it is clear that pectins and hemicellulose are removed from immature pit membranes during hydrolysis, recent observations of amphiphilic lipids and proteins associated with pit membranes raise important questions about drought-induced embolism formation and spread via air-seeding from gas-filled conduits. Indeed, mechanisms behind air-seeding remain poorly understood, which is due in part to little attention paid to the three-dimensional structure of pit membranes in earlier studies. Based on perfusion experiments and modelling, pore constrictions in fibrous pit membranes are estimated to be well below 50 nm, and typically smaller than 20 nm. Together with the low dynamic surface tensions of amphiphilic lipids at air-water interfaces in pit membranes, 5 to 20 nm pore constrictions are in line with the observed xylem water potentials values that generally induce spread of embolism. Moreover, pit membranes appear to show ideal porous medium properties for sap flow to promote hydraulic efficiency and safety due to their very high porosity (pore volume fraction), with highly interconnected, non-tortuous pore pathways, and the occurrence of multiple pore constrictions within a single pore. This three-dimensional view of pit membranes as mesoporous media may explain the relationship between pit membrane thickness and embolism resistance, but is largely incompatible with earlier, two-dimensional views on air-seeding. It is hypothesised that pit membranes enable water transport under negative pressure by producing stable, surfactant coated nanobubbles while preventing the entry of large bubbles that would cause embolism.

Three Dimensional X-Ray Image Synthesis

1972 ◽  
Vol 16 ◽  
pp. 336-343
Author(s):  
David G. Grant
Keyword(s):  
Three Dimensional ◽  
Image Synthesis ◽  
Dimensional Structure ◽  
Cross Sectional ◽  
Projection System ◽  
X Ray ◽  
Optical Projection ◽  
Planar Images ◽  
Scan Length ◽  
Simple Filter

AbstractTomographic systems are able to produce cross sectional planar images of three dimensional volumes because of the relative motion of the source, film and the volume under examination. Analysis shows that the image produced is a result of a three dimensional linear filtering process where the filter characteristics are determined by the scan geometry (3). If, instead of integrating continuously on a single film, a set of N radiographs are recorded, each corresponding to a point along the scan trajectory, then a simple filter can be defined to reconstruct the entire three dimensional structure from this data. In this case, the transfer function exhibits repetitive peaks whose spacing is determined by N and whose width is determined by the total scan length. The number of views required to produce the same “blurring” as the continuous case can then be determined by the Nyquist criteria(3).An optical projection system based on circular geometry for producing three dimensional medical images has been fabricated and tested. The technique can be generalized to any geometry and to all x-ray applications where plane-by-plane examination of a structure would prove beneficial.

A protein related to brain microtubule-associated protein MAP1B is a component of the mammalian centrosome

1994 ◽  
Vol 107 (2) ◽  
pp. 601-611 ◽  
Author(s):  
J.E. Dominguez ◽  
B. Buendia ◽  
C. Lopez-Otin ◽  
C. Antony ◽  
E. Karsenti ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Cultured Cells ◽  
Polyclonal Antibodies ◽  
Microtubule Organizing Center ◽  
Microtubule Associated Proteins ◽  
Organizing Center ◽  
Associated Proteins ◽  
Pericentriolar Material ◽  
Peptide Maps

The centrosome is the main microtubule organizing center of mammalian cells. Structurally, it is composed of a pair of centrioles surrounded by a fibro-granular material (the pericentriolar material) from which microtubules are nucleated. However, the nature of centrosomal molecules involved in microtubules nucleation is still obscure. Since brain microtubule-associated proteins (MAPs) lower the critical tubulin concentration required for microtubule nucleation in tubulin solution in vitro, we have examined their possible association with centrosomes. By immunofluorescence, monoclonal and polyclonal antibodies raised against MAP1B stain the centrosome in cultured cells as well as purified centrosomes, whereas antibodies raised against MAP2 give a completely negative reaction. The MAP1B-related antigen is localized to the pericentriolar material as revealed by immunoelectron microscopy. In preparations of purified centrosomes analyzed on poly-acrylamide gels, a protein that migrates as brain MAP1B is present. After blotting on nitrocellulose, it is decorated by anti-MAP1B antibodies and the amino acid sequence of proteolytic fragments of this protein is similar to brain MAP1B. Moreover, brain MAP1B and its centrosomal counterpart share the same phosphorylation features and have similar peptide maps. These data strongly suggest that a protein homologue to MAP1B is present in centrosomes and it is a good candidate for being involved in the nucleating activity of the pericentriolar material.

Novel Computed Tomography for Reconstructing Three-Dimensional Phase Contrast Images of Single Living Cells

2006 ◽  
Vol 18 (6) ◽  
pp. 827-830
Author(s):  
Yusuke Inoue ◽  
◽  
Ichirou Ishimaru ◽  
Toshiki Yasokawa ◽  
Katsumi Ishizaki ◽  
...  
Keyword(s):  
Refractive Index ◽  
Single Cells ◽  
Three Dimensional ◽  
High Refractive Index ◽  
Cross Sectional ◽  
3 Dimensional ◽  
Index Distribution ◽  
Single Living Cells ◽  
Cellular Components ◽  
Single Living

We proposed using spectroscopy-tomography of single cells as a diagnostic tool for improving early cancer detection and treatment. This technology potentially obtains the 3D distribution of cellular components at high spatial resolution. We used spectroscopy-tomography to generate and analyze a series of cross-sectional images of a borosilicate glass microsphere 10µm in diameter, easily determining the distribution of internal submicron defects in the microsphere. We also used this to estimate the 3-dimensional refractive index distribution in a single human breast cancer cell. The nucleus, which has a high refractive index, is clearly distinguishable.

WIPI2b and Atg16L1: setting the stage for autophagosome formation

2014 ◽  
Vol 42 (5) ◽  
pp. 1327-1334 ◽  
Author(s):  
Michael I. Wilson ◽  
Hannah C. Dooley ◽  
Sharon A. Tooze
Keyword(s):  
Endoplasmic Reticulum ◽  
Regulatory Network ◽  
Recent Progress ◽  
Direct Interaction ◽  
Related Protein ◽  
Autophagosome Formation ◽  
Microtubule Associated Proteins ◽  
Cellular Energy ◽  
Associated Proteins ◽  
Cellular Components

The double-membraned autophagosome organelle is an integral part of autophagy, a process that recycles cellular components by non-selectively engulfing and delivering them to lysosomes where they are digested. Release of metabolites from this process is involved in cellular energy homoeostasis under basal conditions and during nutrient starvation. Selective engulfment of protein aggregates and dysfunctional organelles by autophagosomes also prevents disruption of cellular metabolism. Autophagosome formation in animals is crucially dependent on the unique conjugation of a group of ubiquitin-like proteins in the microtubule-associated proteins 1A/1B light chain 3 (LC3) family to the headgroup of phosphatidylethanolamine (PE) lipids. LC3 lipidation requires a cascade of ubiquitin-like ligase and conjugation enzymes. The present review describes recent progress and discovery of the direct interaction between the PtdIns3P effector WIPI2b and autophagy-related protein 16-like 1 (Atg16L1), a component of the LC3-conjugation complex. This interaction makes the link between endoplasmic reticulum (ER)-localized production of PtdIns3P, triggered by the autophagy regulatory network, and recruitment of the LC3-conjugation complex crucial for autophagosome formation.

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