Morphology of bacilliform particles associated with raspberry vein chlorosis virus

1973 ◽  
Vol 51 (7) ◽  
pp. 1343-1345 ◽  
Author(s):  
Richard Stace-Smith ◽  
Esther Lo
Keyword(s):  
Cross Section ◽  
Vascular Bundle ◽  
Leaf Tissue ◽  
Middle Layer ◽  
Rubus Idaeus ◽  
Regular Surface ◽  
Mesophyll Cells ◽  
Thin Sections ◽  
Parenchyma Cells ◽  
The Mean

Bacilliform particles were found in thin sections of leaves from raspberry (Rubus idaeus L.) infected with raspberry vein chlorosis virus. Similar particles were not found in leaf tissue from a healthy raspberry plant or from a plant infected with raspberry mosaic virus. The bacilliform particles were detected in parenchyma cells within the vascular bundle or mesophyll cells near the vascular bundle. The particles were restricted to the cytoplasm and occurred singly or in bundles of from 2 to 14 parallel particles enclosed within a vesicle. particles were rounded at both ends. the mean dimensions of 42 particles were 506 × 83 nm (ranges: 442 to 560 nm and 73 to 91 nm). in cross section, the particles had three concentric layers, with average diameters of 83 nm, 53 nm, and 23 nm. the wall of each layer was about 70 Å thick and the middle layer showed regular surface striations with a periodicity of 50–55 Å.

Association of malva vein-clearing virus and rhabdoviruslike particles with mottle and vein clearing of malva plants

1986 ◽  
Vol 64 (1) ◽  
pp. 85-89 ◽  
Author(s):  
Maria-Ivone C. Henriques ◽  
Fernando S. Henriques
Keyword(s):  
Inclusion Bodies ◽  
Inner Core ◽  
Dense Body ◽  
Mesophyll Cells ◽  
Cytoplasmic Inclusions ◽  
Thin Sections ◽  
Phloem Parenchyma ◽  
Vein Clearing ◽  
Perinuclear Space ◽  
Parenchyma Cells

Thin sections of malva (Malva sp.) leaves collected in the field and showing mottle and vein-clearing symptoms were examined by electron microscopy. Cytoplasmic inclusions typical of potyvirus and consisting of pinwheels, laminated aggregates, and scrolls were readily observed. In addition, rhabdoviruslike particles were also seen in the perinuclear space of phloem parenchyma cells and within membranous sacs scattered throughout the cytoplasm of other vascular bundle cells. Occasionally rhabdoparticles could be found embedded in an amorphous electron-dense body located within the cell vacuole. The rhabdovirus particles, approximately 75 × 300 nm, were bound by a membrane with outer projections and had an inner core displaying cross striations. The cytoplasm of infected mesophyll cells had chloroplasts containing large amorphous inclusion bodies and had extensive membranous tubules that were frequently associated with the potyvirus inclusions. These ultrastructural aspects, the size of the particles, and the data on host range indicate that malva plants under study were doubly infected by viruses which were tentatively identified as malva vein-clearing virus and a previously undescribed rhabdovirus.

scholarly journals Effects of simulated acid rain on leaf anatomy and micromorphology of Genipa americana L. (Rubiaceae)

2006 ◽  
Vol 49 (2) ◽  
pp. 313-321 ◽  
Author(s):  
Bruno Francisco Sant'Anna-Santos ◽  
Luzimar Campos da Silva ◽  
Aristéa Alves Azevedo ◽  
Rosane Aguiar
Keyword(s):  
Acid Rain ◽  
Leaf Blade ◽  
Leaf Tissue ◽  
Guard Cells ◽  
Simulated Acid Rain ◽  
Spongy Parenchyma ◽  
Mesophyll Cells ◽  
Parenchyma Cells ◽  
Water Ph ◽  
Micromorphological Analysis

Experiments were conducted in order to characterize the injuries on leaf structure and micromorphology of G. americana and evaluate the degree of susceptibility of this species to simulated acid rain. Plants were exposed to acid rain (pH 3.0) for ten consecutive days. Control plants were submitted only to distilled water (pH 6.0). Leaf tissue was sampled and fixed for light and scanning electron microscopy. Necrotic interveinal spots on the leaf blade occurred. Epidermis and mesophyll cells collapse, hypertrophy of spongy parenchyma cells, accumulation of phenolic compounds and starch grains were observed in leaves exposed to acid rain. The micromorphological analysis showed, in necrotic areas, plasmolized guard cells and cuticle rupture. Epidermal and mesophyll cells alterations occurred before symptoms were visualized in the leaves. These results showed the importance of anatomical data for precocious diagnosis injury and to determine the sensitivity of G. americana to acid rain.

Ultrastructure and Senescence in an Achloroplastic Mutant of Hordeum vulgare L. cv. Dyan

1992 ◽  
Vol 50 (1) ◽  
pp. 844-845
Author(s):  
R.H.M. Cross ◽  
C.E.J. Botha ◽  
A.K. Cowan ◽  
B.J. Hartley
Keyword(s):  
Cell Wall ◽  
Hordeum Vulgare ◽  
Leaf Tissue ◽  
Ultrastructural Changes ◽  
Hordeum Vulgare L ◽  
Mesophyll Cells ◽  
Lethal Mutant ◽  
Cytoplasmic Matrix ◽  
Close Proximity ◽  
Pinocytotic Vesicles

Senescence is an ordered degenerative process leading to death of individual cells, organs and organisms. The detection of a conditional lethal mutant (achloroplastic) of Hordeum vulgare has enabled us to investigate ultrastructural changes occurring in leaf tissue during foliar senescence.Examination of the tonoplast structure in six and 14 day-old mutant tissue revealed a progressive degeneration and disappearance of the membrane, apparently starting by day six in the vicinity of the mitochondria associated with the degenerating proplastid (Fig. 1.) where neither of the plastid membrane leaflets is evident (arrows, Fig. 1.). At this stage there was evidence that the mitochondrial membranes were undergoing retrogressive changes, coupled with disorganization of cristae (Fig. 2.). Proplastids (P) lack definitive prolamellar bodies. The cytoplasmic matrix is largely agranular, with few endoplasmic reticulum (ER) cisternae or polyribosomal aggregates. Interestingly, large numbers of actively-budding dictysomes, associated with pinocytotic vesicles, were observed in close proximity to the plasmalemma of mesophyll cells (Fig. 3.). By day 14 however, mesophyll cells showed almost complete breakdown of subcellular organelle structure (Fig. 4.), and further evidence for the breakdown of the tonoplast. The final stage of senescence is characterized by the solubilization of the cell wall due to expression and activity of polygalacturonase and/or cellulose. The presence of dictyosomes with associated pinocytotic vesicles formed from the mature face, in close proximity to both the plasmalemma and the cell wall, would appear to support the model proposed by Christopherson for the secretion of cellulase. This pathway of synthesis is typical for secretory glycoproteins.

The restoration of blurred electron micrographs

1986 ◽  
Vol 44 ◽  
pp. 180-181
Author(s):  
Bridget Carragher ◽  
David A. Bluemke ◽  
Michael J. Potel ◽  
Robert Josephs
Keyword(s):  
Cross Section ◽  
Electron Micrographs ◽  
Relative Motion ◽  
Finite Thickness ◽  
Image Plane ◽  
Helical Axis ◽  
Thin Sections ◽  
Structural Details

We have investigated the feasibility of restoring blurred electron micrographs. Two related problems have been considered; the restoration of images blurred as a result of relative motion between the specimen and the image plane, and the restoration of images which are rotationally blurred about an axis. Micrographs taken while the specimen is drifting result in images which are blurred in the direction of motion. An example of rotational blurring arises in micrographs of thin sections of helical particles viewed in cross section. The twist of the particle within the finite thickness of the section causes the image to appear rotationally blurred about the helical axis. As a result, structural details, particularly at large distances from the helical axis, will be obscured.

Studies on Thrombolysis with Streptokinase

1971 ◽  
Vol 25 (02) ◽  
pp. 354-378 ◽  
Author(s):  
R Gottlob ◽  
L Stockinger ◽  
U Pötting ◽  
G Schattenmann
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Whole Blood ◽  
Jugular Vein ◽  
Thin Sections ◽  
The Third ◽  
Morphological Findings ◽  
Blood Clots ◽  
Arteries And Veins

SummaryIn vitro whole blood clots of various ages, experimental thrombi produced in the jugular vein of rabbits and human thrombi from arteries and veins were examined in semi-thin sections and by means of electron microscopy.In all types of clots examined a typical course of retraction was found. Retraction starts with a dense excentrical focus which grows into a densification ring. After 24 hours the entire clot becomes almost homogeneously dense; later a secondary swelling sets in.Shortly after coagulation the erythrocytes on the rim of the clot are bi-concave discs. They then assume the shape of crenate spheres, turn into smooth spheres and finally become indented ghosts which have lost the largest part of their contents. In the inner zone, which makes up the bulk of the clot, we observed bi-concave discs prior to retraction. After retraction we see no crenations but irregularly shaped erythrocytes. Once the secondary swelling sets in, the cross-section becomes polygonal and later spherical. After extensive hemolysis we observe the “retiform thrombus” made up of ghosts.Experimental and clinical thrombi present the same morphology but are differentiated from in vitro clots by: earlier hemolysis, immigration of leukocytes, formation of a rim layer consisting of fibrin and thrombocytes, and the symptoms of organization. Such symptoms of organization which definitely will prevent lysis with streptokinase were found relatively late in experimental and clinical thrombi. Capillary buds and capillary loops were never found in clinical thrombi prior to the third month.The morphological findings agree with earlier physical and enzymatic investigations. The observation that phenomena of reorganization occur relatively late and frequently only in the rim areas of large thrombi explains why lytic therapy is possible in some of the chronic obliterations.

scholarly journals Sources of Variability in the Response of Labeled Microspheres and B Cells during the Analysis by a Flow Cytometer

2021 ◽  
Vol 22 (15) ◽  
pp. 8256
Author(s):  
Adolfas K. Gaigalas ◽  
Yu-Zhong Zhang ◽  
Linhua Tian ◽  
Lili Wang
Keyword(s):  
B Cells ◽  
Laser Beam ◽  
Cross Section ◽  
Mean Fluorescence Intensity ◽  
Numerical Aperture ◽  
Flow Cytometer ◽  
Fluorescence Signal ◽  
Minor Importance ◽  
Reliable Measure ◽  
The Mean

A stochastic model of the flow cytometer measurement process was developed to assess the nature of the observed coefficient of variation (CV%) of the mean fluorescence intensity (MFI) from a population of labeled microspheres (beads). Several sources of variability were considered: the total number of labels on a bead, the path through the laser beam, the optical absorption cross-section, the quantum yield, the numerical aperture of the collection optics, and the photoelectron conversion efficiency of the photomultiplier (PMT) cathode. The variation in the number of labels on a bead had the largest effect on the CV% of the MFI of the bead population. The variation in the path of the bead through the laser beam was minimized using flat-top lasers. The variability in the average optical properties of the labels was of minor importance for beads with sufficiently large number of labels. The application of the bead results to the measured CV% of labeled B cells indicated that the measured CV% was a reliable measure of the variability of antibodies bound per cell. With some modifications, the model can be extended to multicolor flow cytometers and to the study of CV% from cells with low fluorescence signal.

Effects of Pin Shape and Array Orientation on Heat Transfer and Pressure Loss in Pin Fin Arrays

1984 ◽  
Vol 106 (1) ◽  
pp. 252-257 ◽  
Author(s):  
D. E. Metzger ◽  
C. S. Fan ◽  
S. W. Haley
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Pressure Loss ◽  
Flow Direction ◽  
Circular Cross Section ◽  
Cycle Performance ◽  
Mean Flow ◽  
Pin Fin ◽  
The Mean ◽  
Cooling Air

Modern high-performance gas turbine engines operate at high turbine inlet temperatures and require internal convection cooling of many of the components exposed to the hot gas flow. Cooling air is supplied from the engine compressor at a cost to cycle performance and a design goal is to provide necessary cooling with the minimum required cooling air flow. In conjunction with this objective, two families of pin fin array geometries which have potential for improving airfoil internal cooling performance were studied experimentally. One family utilizes pins of a circular cross section with various orientations of the array with respect to the mean flow direction. The second family utilizes pins with an oblong cross section with various pin orientations with respect to the mean flow direction. Both heat transfer and pressure loss characteristics are presented. The results indicate that the use of circular pins with array orientation between staggered and inline can in some cases increase heat transfer while decreasing pressure loss. The use of elongated pins increases heat transfer, but at a high cost of increased pressure loss. In conjunction with the present measurements, previously published results were reexamined in order to estimate the magnitude of heat transfer coefficients on the pin surfaces relative to those of the endwall surfaces. The estimate indicates that the pin surface coefficients are approximately double the endwall values.

Le système radiculaire dans les érablières du Québec. I. Nouvelle méthode d'estimation du volume et de la masse des radicelles

1992 ◽  
Vol 22 (10) ◽  
pp. 1562-1567 ◽  
Author(s):  
Fernand Pagé ◽  
Bady Badibanga ◽  
Annie Sauvesty ◽  
Colette Ansseau
Keyword(s):  
Standard Deviation ◽  
Sugar Maple ◽  
Soil Samples ◽  
Diameter Class ◽  
Thin Sections ◽  
Truncated Cone ◽  
The Mean ◽  
Diameter Classes

A method for rapidly estimating the rootlet volume and mass in sugar maple groves was developed in relation with the rootlet size. Soil samples were obtained with corers and cut in 2-cm thick slices. The number of rootlets of diameter classes <0.3, 0.3–0.5, 0.5–0.8, and 0.8–1.0 mm were determined under microscope (× 150) on the upper surface of slices. Rootlet surface for each class was measured on thin sections of soil, with an optic microscope connected to a digitalizing board. Mean rootlet surface [Formula: see text] showed a small standard deviation within each diameter class. The rootlet surface (S) on a surface of soil St can be estimated as [Formula: see text], where N is the number of rootlets observed in nc fields of observation, each field having a surface So. If two soil slices are located at depths h1 and h2, respectively, and if the rootlet surfaces of those slices are S1 and S2, the rootlet volume V of the first slice corresponds approximately to the volume of a truncated cone, and can be calculated as V = [S1 + S2 + (S1S2)0,5] (h2–h1)/3. The rootlet density (g•cm−3 of root) was also determined for each diameter class. The standard deviation from [Formula: see text], the mean density for each diameter class was small. Thus, the rootlet mass M was determined as [Formula: see text]. Estimated and real rootlet volume and mass values were compared. A difference of about 10% was found between estimated and real values.

A theory of incoherent scattering of radio waves by a plasma

1960 ◽  
Vol 259 (1296) ◽  
pp. 79-99 ◽  
Keyword(s):  
Cross Section ◽  
Thermal Fluctuations ◽  
Incoherent Scattering ◽  
Doppler Broadening ◽  
Radio Waves ◽  
Central Frequency ◽  
Resonance Effects ◽  
Doppler Shifts ◽  
The Mean ◽  
Free Plasma

A theory is developed which describes the scattering of radio waves by the random thermal fluctuations of electron density in a collision-free plasma. The frequency spectrum, as well as the amplitude, of the scattered radiation is calculated. Particular attention is paid to the part of the spectrum which corresponds to small Doppler shifts, this being the region of greatest significance in connexion with the phenomenon of incoherent scattering from the ionosphere. The calculations are based on a generalized version of Nyquist’s noise theorem, and they lead to the following conclusions: (1) The mean scattering cross-section for the ionosphere is equal to that which would exist if each of the electrons scattered independently with a cross-section of one-half the classical Thomson cross-section. (2) The mean Doppler broadening of the scattered signal corresponds roughly to the speed of the ions rather than to that of the electrons. (3) The spectral shape of this signal is not Gaussian. There is a mild maximum in the spectrum away from the central frequency, as can be seen in figure 1. (4) Plasma resonance effects contribute only negligibly to the scattering for frequencies currently of interest.

scholarly journals Localization of DNA in the fibrillar components of the nucleolus: a cytochemical and morphometric study.

1993 ◽  
Vol 41 (6) ◽  
pp. 829-836 ◽  
Author(s):  
M Derenzini ◽  
F Farabegoli ◽  
D Trerè
Keyword(s):  
Morphometric Analysis ◽  
Mean Value ◽  
Morphometric Study ◽  
Dense Fibrillar Component ◽  
Thin Sections ◽  
Fibrillar Center ◽  
The Mean ◽  
Fibrillar Component ◽  
Resting Lymphocytes ◽  
The Relationship

We studied the distribution of DNA in human circulating lymphocyte nucleoli using three different cytochemical methods for selective visualization of DNA in thin sections: the Feulgen-like osmium-ammine reaction, the NAMA-Ur procedure, and the osmium-ammine staining in glycine buffer, pH 1.5. All three methods indicated the presence of uniformly distributed, highly decondensed DNA filaments forming a large solitary agglomerate in the central part of the nucleolar area, corresponding to the solitary large fibrillar center (FC) as revealed by uranium and lead staining. We also studied the relationship between DNA agglomerates and nucleolar fibrillar components in resting and phytohemagglutinin (PHA)-stimulated lymphocytes by morphometric analysis of the areas occupied by these structures. In resting lymphocytes the mean area of the DNA agglomerates was 0.479 micron 2 +/- 0.161 SD, whereas that of FCs was 0.380 micron 2 +/- 0.149 SD, with a ratio of 1.26. In PHA-stimulated lymphocytes the mean area of the DNA agglomerates was 0.116 micron 2 +/- 0.056 SD, whereas that of the FCs was 0.075 micron 2 +/- 0.032 SD, with a ratio of 1.55. In PHA-stimulated lymphocytes we also measured the area occupied by the FCs plus the closely associated dense fibrillar component (DFC). The mean value of these two fibrillar components was 0.206 micron 2 +/- 0.081 SD. These data demonstrate that decondensed DNA filaments are uniformly distributed in the FCs and that in transcriptionally active nucleoli they are also present in the proximal portion of the DFC surrounding the FCs.

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