scholarly journals ELECTRON MICROSCOPE STUDIES ON SOMA-SOMATIC INTERNEURONAL JUNCTIONS IN THE CORPUS PEDUNCULATUM OF THE WOOD ANT (FORMICA LUGUBRIS ZETT.)

1966 ◽  
Vol 28 (2) ◽  
pp. 391-403 ◽  
Author(s):  
Alex M. Landolt ◽  
Hans Ris
Keyword(s):  
Dynamic Properties ◽  
Average Diameter ◽  
Striking Similarity ◽  
Close Proximity ◽  
Corpora Pedunculata ◽  
Average Surface Area ◽  
A Subunit ◽  
Transfer Of Information ◽  
Formica Lugubris ◽  
Neuron Pool

1. The corpora pedunculata of the wood ant (Formica lugubris Zett.) contain densely packed neuron perikarya which are separated by ultrathin glial sheaths. 2. These glial sheaths are occasionally interrupted by round holes with an average surface area of 2.64 µ2. The holes are designated glial windows since they represent intracellular gaps of glial cytoplasm. 3. The glial windows allow soma-somatic interneuronal junctions. Of all adjacent neurons in a selected neuron pool, only 42% were interconnected by such junctions. 4. The intercellular space at the soma-somatic junctions has an average diameter of 30 A; occasionally, it is collapsed and an external compound membrane ensues. The junctional membranes are characterized by the presence of a subunit pattern of cross-directional electron-opaque lines with a 50- to 70-A periodicity. 5. Morphological signs of chemical transmission are absent in these junctions. On the other hand, there is a striking similarity in structural organization between soma-somatic junctions and electrical synapses described in other species. Therefore, it is suggested that these cell contacts of the ant's "cerebral cortex" are another form of electrical junction. 6. The close proximity of the junctions to the cell nucleus is noted. Its significance could not be ascertained. 7. The suggestion is made that glial windows may have dynamic properties and may intervene in the regulation of interneuronal transfer of information.

scholarly journals Super Resolution Optical Microscopy for Analysis of Granules in B-Cell Acute Lymphoblastic Leukemia

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 5347-5347
Author(s):  
Rio Barrere-Cain ◽  
Sebastian Wachsmann-Hogiu ◽  
Denis M. Dwyre
Keyword(s):  
Bone Marrow ◽  
Surface Area ◽  
Bone Marrow Aspirate ◽  
Lymphoblastic Leukemia ◽  
Average Diameter ◽  
Maximum Intensity ◽  
Average Depth ◽  
Average Surface Area ◽  
High Resolution Images ◽  
Cell Acute Lymphoblastic Leukemia

Abstract An unusual case of B-cell acute lymphoblastic leukemia (B-ALL) was diagnosed at our institution. The B-ALL had unusually large prominent granules, but the diagnosis was confirmed by flow cytometry. Using structured illumination microscopy (SIM), we obtained high resolution images of the granules in the lymphoblasts. With these high resolution images, we acquired detailed quantitative information on the morphology of these unusual cells. We compared the morphology of this unusual B-ALL case with granular acute myeloid leukemia (AML) cases, standard B-ALL cases, and non-leukemic marrow aspirate specimens. Granular B-ALL can sometimes be misdiagnosed as AML, which would result in patients not receiving the optimal treatment. Our goal is to study the structure of these unusual B-ALL cases. More information characterizing the granules may assist in understanding how these leukemic lymphoblasts function. Granules in B-ALL are believed to be abnormal organelle formations or fusions. Electron microscopy (EM) reveals that the granules resemble membrane bound vesicles and it has been suggested that they are atypical mitochondria, lysosomes, or damaged chromosomes. These suggestions have been based on EM images and the cytochemical profile of the cells (Pitman et al., 2007; Cap et al., 2000). To our knowledge, granular B-ALL lymphoblasts have never been imaged with SIM. We took images of the same cells using both brightfield light microscopy and SIM. Figures 2 and 3 show the same cells imaged with both microscopes. We made maximum intensity Z projections (the pixels in stack of images with maximum intensity projected onto one image), cutting off Z-slices where the cell was not focused in order to avoid measuring granules outside the cell. Next, we randomly selected granules to measure in each cell's Z projection. Using Image J software, we measured the surface area, diameter, depth, intensity relative to background, and shortest distance to nucleus and plasma membrane for each individual granule. We then averaged the measurements from each type of sample (granular B-ALL, AML, non-leukemic). The granules in B-ALL had an average diameter of .285 micrometers, average depth of .506 micrometers, average surface area of .147 micrometers squared, and were on average 2.74 times more intense than the background. The granules in AML had an average diameter of .479 micrometers, average depth of .440 micrometers, average surface area of .2255 micrometers squared, and were on average 1.953 times more intense than the background. The B-ALL granules were smaller and more intense. The stain used for the cytoplasm, eosin, is acidic. The brighter B-ALL granules suggest that they have higher concentrations of basic proteins than the AML granules. This technique may be useful in separating granules in AML leukemia, ALL leukemias, and possibly leukemias of ambiguous lineage. Other techniques we are investigating include automated count of granules and granule characterization with Raman Spectroscopy to determine chemical composition. Evaluating the cells with fluorescent probes that specifically attach to either lysosomes or mitochondria may give additional biochemical information about the granules/leukemias. Matching fluorescent signals from these probes to granules in ALL may assist in determining whether the granules are lysosomal or mitochondrial in origin. Figure 1: Granular B-ALL bone marrow aspirate sample imaged with SIM and converted to a maximum intensity Z projection, arrow indicates a granule Figure 1:. Granular B-ALL bone marrow aspirate sample imaged with SIM and converted to a maximum intensity Z projection, arrow indicates a granule Figure 2: AML bone marrow aspirate sample imaged with SIM and converted to a maximum intensity Z projection, arrow indicates a granule Figure 2:. AML bone marrow aspirate sample imaged with SIM and converted to a maximum intensity Z projection, arrow indicates a granule Figure 3: AML bone marrow aspirate sample imaged with a brightfield light microscope and magnified 100 times, arrows indicate granules Figure 3:. AML bone marrow aspirate sample imaged with a brightfield light microscope and magnified 100 times, arrows indicate granules Disclosures No relevant conflicts of interest to declare.

scholarly journals Lysosome Dynamic Properties during Neuronal Stem Cell Differentiation Studied by Spatiotemporal Fluctuation Spectroscopy and Organelle Tracking

2020 ◽  
Vol 21 (9) ◽  
pp. 3397 ◽  
Author(s):  
William Durso ◽  
Manuella Martins ◽  
Laura Marchetti ◽  
Federico Cremisi ◽  
Stefano Luin ◽  
...  
Keyword(s):  
Stem Cell ◽  
Dynamic Properties ◽  
Mean Square Displacement ◽  
Stem Cell Differentiation ◽  
Average Diameter ◽  
Single Particle Tracking ◽  
Dynamic Responses ◽  
Embryonic Cells ◽  
Dynamic Features ◽  
Neuronal Stem Cell

We investigated lysosome dynamics during neuronal stem cell (NSC) differentiation by two quantitative and complementary biophysical methods based on fluorescence: imaging-derived mean square displacement (iMSD) and single-particle tracking (SPT). The former extracts the average dynamics and size of the whole population of moving lysosomes directly from imaging, with no need to calculate single trajectories; the latter resolves the finest heterogeneities and dynamic features at the single-lysosome level, which are lost in the iMSD analysis. In brief, iMSD analysis reveals that, from a structural point of view, lysosomes decrement in size during NSC differentiation, from 1 μm average diameter in the embryonic cells to approximately 500 nm diameter in the fully differentiated cells. Concomitantly, iMSD analysis highlights modification of key dynamic parameters, such as the average local organelle diffusivity and anomalous coefficient, which may parallel cytoskeleton remodeling during the differentiation process. From average to local, SPT allows mapping heterogeneous dynamic responses of single lysosomes in different districts of the cells. For instance, a dramatic decrease of lysosomal transport in the soma is followed by a rapid increase of transport in the projections at specific time points during neuronal differentiation, an observation compatible with the hypothesis that lysosomal active mobilization shifts from the soma to the newborn projections. Our combined results provide new insight into the lysosome size and dynamics regulation throughout NSC differentiation, supporting new functions proposed for this organelle.

Restricted Dynamics in Polymer-Filler Systems

2000 ◽  
Vol 661 ◽  
Author(s):  
V. Arrighi ◽  
S. Gagliardi ◽  
Julia S. Higgins
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Dynamic Properties ◽  
Polymeric Materials ◽  
Weight Fraction ◽  
Average Diameter ◽  
Hydrogen Atoms ◽  
Polymer Filler ◽  
Wide Range

ABSTRACTComposites in which fibres or fillers are incorporated into a polymeric component exhibit improved mechanical strength compared to the polymer matrix. This reinforcement effect strongly depends on the properties of the interphase and the specific interactions between the polymer and the reinforcing additive.A wide range of experimental methods have been used to assess the effect of active fillers on the mobility of the polymer chains. The experimental results from NMR, dielectric spectroscopy and dynamical thermal analysis reveal that the mobility of chain units adjacent to the adsorbed surface differs considerably from the bulk.We have used quasielastic neutron scattering to investigate the dynamic properties of poly(dimethyl siloxane) (PDMS) filled with silica particles. This technique which probes the motion of the hydrogen atoms has been extensively used to study the local dynamics of polymeric materials. In this paper we show that QENS provides detailed information on the reduced mobility of chain segments in polymer-filler systems.QENS measurements were carried out on PDMS filled with hydrophilic Aerosil with different specific surface area (average diameter 7 and 20 nm). Detailed data analysis indicates that the QENS spectra of the polymer-filler composites can be described by the sum of two contributions: (a) a quasielastic component due to chains not affected by the presence of the fillers and (b) an elastic term from those chain segments strongly affected by the presence of fillers. The latter depends on the specific surface area of the particles and their weight fraction in the composite.

scholarly journals Role of Tim50 in the Transfer of Precursor Proteins from the Outer to the Inner Membrane of Mitochondria

2009 ◽  
Vol 20 (5) ◽  
pp. 1400-1407 ◽  
Author(s):  
Dejana Mokranjac ◽  
Martin Sichting ◽  
Dušan Popov-Čeleketić ◽  
Koyeli Mapa ◽  
Lada Gevorkyan-Airapetov ◽  
...  
Keyword(s):  
Intermembrane Space ◽  
Concerted Action ◽  
Mitochondrial Membranes ◽  
Inner Membrane ◽  
Close Proximity ◽  
Precursor Proteins ◽  
The Matrix ◽  
A Subunit ◽  
Efficient Transfer

Transport of essentially all matrix and a number of inner membrane proteins is governed, entirely or in part, by N-terminal presequences and requires a coordinated action of the translocases of outer and inner mitochondrial membranes (TOM and TIM23 complexes). Here, we have analyzed Tim50, a subunit of the TIM23 complex that is implicated in transfer of precursors from TOM to TIM23. Tim50 is recruited to the TIM23 complex via Tim23 in an interaction that is essentially independent of the rest of the translocase. We find Tim50 in close proximity to the intermembrane space side of the TOM complex where it recognizes both types of TIM23 substrates, those that are to be transported into the matrix and those destined to the inner membrane, suggesting that Tim50 recognizes presequences. This function of Tim50 depends on its association with TIM23. We conclude that the efficient transfer of precursors between TOM and TIM23 complexes requires the concerted action of Tim50 with Tim23.

Two Distinct Types of Microfilaments in the Cytoplasm of Human Adenohypophysial Cells

1973 ◽  
Vol 31 ◽  
pp. 668-669
Author(s):  
E. Horvath ◽  
K. Kovacs ◽  
I. E. Stratmann ◽  
C. Ezrin
Keyword(s):  
Pituitary Tumors ◽  
Average Diameter ◽  
Anterior Lobe ◽  
Uranyl Acetate ◽  
Type I ◽  
Breast Cancer Patients ◽  
Human Pituitary ◽  
Severe Diabetes ◽  
Pituitary Glands ◽  
Membrane Bound

Surgically removed human pituitary glands as well as pituitary tumors fixed in glutaraldehyde, postfixed in osmium tetroxide, embedded in epon resin, stained with uranyl acetate and lead citrate have been investigated by electron microscopy in order to correlate ultrastructure with functional activity. In the course of this study two distinct types of microfilaments have been identified in the cytoplasm of adenohypophysiocytes.Type I microfilaments (Fig. 1) were found in the cytoplasm of anterior lobe cells of five female subjects with disseminated mammary cancer and two patients with severe diabetes mellitus. The breast cancer patients were treated pre-operatively for various periods of time with different doses of oxysteroids. The microfilaments had an average diameter of JO A, formed parallel bundles, were scattered irregularly in the cytoplasm and were frequently located in the perikaryon. They were not membrane-bound and failed to show any periodicity.

Effects of Vincristine on Endothelial Microtubules in the Spinal Cord

1976 ◽  
Vol 34 ◽  
pp. 58-59
Author(s):  
John L. Beggs ◽  
John D. Waggener ◽  
Wanda Miller
Keyword(s):  
Spinal Cord ◽  
Biological Activity ◽  
Horseradish Peroxidase ◽  
Transport Mechanism ◽  
Vasogenic Edema ◽  
Vesicular Transport ◽  
Close Proximity

Microtubules (MT) are versatile organelles participating in a wide variety of biological activity. MT involvement in the movement and transport of cytoplasmic components has been well documented. In the course of our study on trauma-induced vasogenic edema in the spinal cord we have concluded that endothelial vesicles contribute to the edema process. Using horseradish peroxidase as a vascular tracer, labeled endothelial vesicles were present in all situations expected if a vesicular transport mechanism was in operation. Frequently,labeled vesicles coalesced to form channels that appeared to traverse the endothelium. The presence of MT in close proximity to labeled vesicles sugg ested that MT may play a role in vesicular activity.

Imaging of platinum-shadowed macromolecular complexes in dark field

1984 ◽  
Vol 42 ◽  
pp. 146-147
Author(s):  
D.W. Andrews ◽  
F.P. Ottensmeyer
Keyword(s):  
Thin Film ◽  
Three Dimensional ◽  
Average Diameter ◽  
Dark Field ◽  
Bright Field ◽  
Field Mode ◽  
Macromolecular Complexes ◽  
Average Mass ◽  
Topological Features ◽  
Projection Images

Shadowing with heavy metals has been used for many years to enhance the topological features of biological macromolecular complexes. The three dimensional features present in directionaly shadowed specimens often simplifies interpretation of projection images provided by other techniques. One difficulty with the method is the relatively large amount of metal used to achieve sufficient contrast in bright field images. Thick shadow films are undesirable because they decrease resolution due to an increased tendency for microcrystalline aggregates to form, because decoration artefacts become more severe and increased cap thickness makes estimation of dimensions more uncertain.The large increase in contrast provided by the dark field mode of imaging allows the use of shadow replicas with a much lower average mass thickness. To form the images in Fig. 1, latex spheres of 0.087 μ average diameter were unidirectionally shadowed with platinum carbon (Pt-C) and a thin film of carbon was indirectly evaporated on the specimen as a support.

Digital image processing methods applied to the study of annealing time on semiconductor-metal eutectic composites

1988 ◽  
Vol 46 ◽  
pp. 848-849
Author(s):  
J. Hefter
Keyword(s):  
Image Processing ◽  
Digital Image Processing ◽  
Digital Image ◽  
Electronic Device ◽  
Processing System ◽  
Average Diameter ◽  
Eutectic Solidification ◽  
Metal Silicide ◽  
The Matrix ◽  
Microscopic Studies

Semiconductor-metal composites, formed by the eutectic solidification of silicon and a metal silicide have been under investigation for some time for a number of electronic device applications. This composite system is comprised of a silicon matrix containing extended metal-silicide rod-shaped structures aligned in parallel throughout the material. The average diameter of such a rod in a typical system is about 1 μm. Thus, characterization of the rod morphology by electron microscope methods is necessitated.The types of morphometric information that may be obtained from such microscopic studies coupled with image processing are (i) the area fraction of rods in the matrix, (ii) the average rod diameter, (iii) an average circularity (roundness), and (iv) the number density (Nd;rods/cm2). To acquire electron images of these materials, a digital image processing system (Tracor Northern 5500/5600) attached to a JEOL JXA-840 analytical SEM has been used.

The distribution of antigen on the surface of RBL-2H3 rat basophilic leukemia cells observed by back-scattered electron imaging

1986 ◽  
Vol 44 ◽  
pp. 274-275
Author(s):  
R.F. Stump ◽  
J.R. Pfeiffer ◽  
JC. Seagrave ◽  
D. Huskisson ◽  
J.M. Oliver
Keyword(s):  
Cell Surface ◽  
Dynamic Properties ◽  
Leukemia Cells ◽  
Antigen Binding ◽  
Scattered Electron ◽  
Ige Receptor ◽  
Receptor Complexes ◽  
Rat Basophilic Leukemia Cells ◽  
Electron Imaging ◽  
Basophilic Leukemia

In RBL-2H3 rat basophilic leukemia cells, antigen binding to cell surface IgE-receptor complexes stimulates the release of inflammatory mediators and initiates a series of membrane and cytoskeletal events including a transformation of the cell surface from a microvillous to a lamellar topography. It is likely that dynamic properties of the IgE receptor contribute to the activation of these responses. Fewtrell and Metzger have established that limited crosslinking of IgE-receptor complexes is essential to trigger secretion. In addition, Baird and colleagues have reported that antigen binding causes a rapid immobilization of IgE-receptor complexes, and we have demonstrated an apparent increase with time in the affinity of IgE-receptor complexes for antigen.

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