Ultrastructural study of the teguminal sheaths of two metastrongyloid nematodes

1970 ◽  
Vol 48 (3) ◽  
pp. 423-425 ◽  
Author(s):  
P. H. G. Stockdale ◽  
M. A. Fernando ◽  
J. Gilroy
Keyword(s):  
Ultrastructural Study ◽  
Basal Layer ◽  
Low Density ◽  
Surface Layers ◽  
Outer Cortex ◽  
Crenosoma Vulpis ◽  
Outer Sheath ◽  
Nematode Cuticle

The ultrastructure of the surface layers of two metastrongyloid nematodes, Crenosoma vulpis and Perostrongylus pridhami, is described. The cuticles of both worms consist of the three basic layers of a typical nematode cuticle: an outer cortex, a middle matrix, and an inner basal layer. The "teguminal sheath" described as an outer sheath in certain metastrongyloids appears to correspond to the cortex in both the nematodes studied. The very wide matrix of low-density material separating the outer cortex from the inner basal layer of the cuticle is thought to have led to the concept that the "teguminal sheath" is a loose membranous sheath enveloping the nematode.

scholarly journals Kugelzellen in larval anuran epidermis: an ultrastructural study on tadpoles of Pelobates cultripes (Pelobatidae) and Phyllobates bicolor (Dendrobatidae)

2007 ◽  
Vol 76 (4) ◽  
pp. 213-220 ◽  
Author(s):  
Giovanni Delfino ◽  
Sara Quagliata ◽  
Filippo Giachi ◽  
Cecilia Malentacchi
Keyword(s):  
Cell Surface ◽  
Ultrastructural Study ◽  
Limb Development ◽  
Leydig Cells ◽  
Hind Limb ◽  
Three Dimensional ◽  
Basal Layer ◽  
Dimensional Network ◽  
Clawed Frog ◽  
Pelobates Cultripes

Prior to hind limb development, tadpoles of the western spadefoot frog Pelobates cultripes (Pelobatidae) and dart-arrow frog Phyllobates bicolor (Dendrobatidae) possess large clear cells in the basal layer of the epidermis. These cells closely resemble Kugelzellen (KZn) of larval clawed frog, Xenopus laevis (Pipidae) and share ultrastructural traits with Leydig cells (LCs) of Caudata and Caecilia. In both species, KZn possess a transparent cytoplasm and a remarkable peripheral cytoskeleton of tonofilaments: in the arrow frog tonofilaments form bands parallel to the cell surface, in the spadefoot frog thin bundles, arranged in a three-dimensional network. KZn combine turgor (resulting from the hydrated cytoplasm) with stiffness (from peripheral cytoskeleton), thus providing structural stability to the larval epidermis.

scholarly journals Testing the Use of Bomb Radiocarbon to Date the Surface Layers of Blanket Peat

Radiocarbon ◽  
2004 ◽  
Vol 46 (2) ◽  
pp. 841-851 ◽  
Author(s):  
M H Garnett ◽  
A C Stevenson
Keyword(s):  
Mass Spectrometry ◽  
Plant Material ◽  
Plant Macrofossils ◽  
Low Density ◽  
Surface Layers ◽  
Broad Agreement ◽  
Blanket Peat ◽  
Bomb Radiocarbon ◽  
Final Interpretation

The recently formed surface layers of peatlands are archives of past environmental conditions and can have a temporal resolution considerably greater than deeper layers. The low density and conditions of fluctuating water table have hindered attempts to construct chronologies for these peats. We tested the use of the radiocarbon bomb pulse to date recently accumulated peat in a blanket mire. The site was chosen because the peat profiles contained independent chronological markers in the form of charcoal-rich layers produced from known burning events. We compared chronologies derived from accelerator mass spectrometry 14C analysis of plant macrofossils against these chronological markers. The bomb 14C-derived chronologies were in broad agreement with the charcoal dating evidence. However, there were uncertainties in the final interpretation of the 14C results because the pattern of 14C concentration in the peat profiles did not follow closely the known atmospheric 14C record. Furthermore, samples of different macrofossil materials from the same depth contained considerable differences in 14C. Suggested explanations for the observed results include the following: i) minor disturbance at the site, ii) in-situ contamination of the 14C samples by carbonaceous soot, and iii) differential incorporation of plant material during blanket peat growth.

Adhesive Contact in Surface Layers of Low-Density Polyethylene Irradiated in Air

2003 ◽  
Vol 37 (6) ◽  
pp. 373-375 ◽  
Author(s):  
V. V. Smirnov ◽  
V. N. Aderikha ◽  
Yu. M. Pleskachevskii ◽  
S. A. Khakhuda ◽  
V. M. Makarenko ◽  
...  
Keyword(s):  
Adhesive Contact ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Surface Layers

scholarly journals The morphogenetic protein CotE drives exosporium formation by positioning CotY and ExsY during sporulation of Bacillus cereus

2020 ◽  
Author(s):  
Armand Lablaine ◽  
Monica Serrano ◽  
Stéphanie Chamot ◽  
Isabelle Bornard ◽  
Frédéric Carlin ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Fluorescence Microscopy ◽  
Bacillus Cereus ◽  
Basal Layer ◽  
Super Resolution ◽  
Spore Surface ◽  
Surface Layers ◽  
Clostridium Species ◽  
Localization Pattern ◽  
Morphogenetic Protein

The exosporium is the outermost spore layer of some Bacillus and Clostridium species and related organisms. It mediates interactions of spores with their environment, modulates spore adhesion and germination and could be implicated in pathogenesis. The exosporium is composed of a crystalline basal layer, formed mainly by the two cysteine-rich proteins CotY and ExsY, and surrounded by a glycoprotein hairy nap. The morphogenetic protein CotE is necessary for Bacillus cereus exosporium integrity, but how CotE directs exosporium assembly remains unknown. Here, we followed the localization of SNAP-tagged CotE, -CotY and -ExsY during B. cereus sporulation, using super-resolution fluorescence microscopy and evidenced interactions among these proteins. CotE, CotY and ExsY are present as complexes at all sporulation stages and follow a similar localization pattern during endospore formation that is reminiscent of the localization of Bacillus subtilis CotE. We show that B. cereus CotE drives the formation of one cap at both forespore poles by positioning CotY and then guides forespore encasement by ExsY, thereby promoting exosporium elongation. By these two actions, CotE ensures the formation of a complete exosporium. Importantly, we demonstrate that the assembly of the exosporium is not a unidirectional process as previously proposed but it is performed through the formation of two caps, as observed during B. subtilis coat morphogenesis. It appears that a general principle governs the assembly of the spore surface layers of Bacillaceae.

scholarly journals The Morphogenetic Protein CotE Positions Exosporium Proteins CotY and ExsY during Sporulation of Bacillus cereus

mSphere ◽  
2021 ◽  
Vol 6 (2) ◽  
Author(s):  
Armand Lablaine ◽  
Mònica Serrano ◽  
Christelle Bressuire-Isoard ◽  
Stéphanie Chamot ◽  
Isabelle Bornard ◽  
...  
Keyword(s):  
Fluorescence Microscopy ◽  
Bacillus Cereus ◽  
Basal Layer ◽  
Super Resolution ◽  
Host Cells ◽  
Surface Layers ◽  
Content Type ◽  
Localization Pattern ◽  
Morphogenetic Protein ◽  
Environmental Interactions

ABSTRACT The exosporium is the outermost spore layer of some Bacillus and Clostridium species and related organisms. It mediates the interactions of spores with their environment, modulates spore adhesion and germination, and has been implicated in pathogenesis. In Bacillus cereus, the exosporium consists of a crystalline basal layer, formed mainly by the two cysteine-rich proteins CotY and ExsY, surrounded by a hairy nap composed of glycoproteins. The morphogenetic protein CotE is necessary for the integrity of the B. cereus exosporium, but how CotE directs exosporium assembly remains unknown. Here, we used super-resolution fluorescence microscopy to follow the localization of SNAP-tagged CotE, CotY, and ExsY during B. cereus sporulation and evidenced the interdependencies among these proteins. Complexes of CotE, CotY, and ExsY are present at all sporulation stages, and the three proteins follow similar localization patterns during endospore formation that are reminiscent of the localization pattern of Bacillus subtilis CotE. We show that B. cereus CotE guides the formation of one cap at both forespore poles by positioning CotY and then guides forespore encasement by ExsY, thereby promoting exosporium elongation. By these two actions, CotE ensures the formation of a complete exosporium. Importantly, we demonstrate that the assembly of the exosporium is not a unidirectional process, as previously proposed, but occurs through the formation of two caps, as observed during B. subtilis coat morphogenesis, suggesting that a general principle governs the assembly of the spore surface layers of Bacillaceae. IMPORTANCE Spores of Bacillaceae are enveloped in an outermost glycoprotein layer. In the B. cereus group, encompassing the Bacillus anthracis and B. cereus pathogens, this layer is easily recognizable by a characteristic balloon-like appearance and separation from the underlying coat by an interspace. In spite of its importance for the environmental interactions of spores, including those with host cells, the mechanism of assembly of the exosporium is poorly understood. We used super-resolution fluorescence microscopy to directly visualize the formation of the exosporium during the sporulation of B. cereus, and we studied the localization and interdependencies of proteins essential for exosporium morphogenesis. We discovered that these proteins form a morphogenetic scaffold before a complete exosporium or coat is detectable. We describe how the different proteins localize to the scaffold and how they subsequently assemble around the spore, and we present a model for the assembly of the exosporium.

Morphological aspects of the shedding of surface layers from peanut roots

1997 ◽  
Vol 75 (4) ◽  
pp. 607-611 ◽  
Author(s):  
Eiji Uheda ◽  
Yoko Akasaka ◽  
Hiroyuki Daimon
Keyword(s):  
Arachis Hypogaea ◽  
Cell Separation ◽  
Cell Walls ◽  
Separation Process ◽  
Surface Layers ◽  
Outer Cortex ◽  
Electron Microscopic ◽  
Intact Cells ◽  
Morphological Aspects ◽  
Microscopic Studies

Epidermal cells and cells originating in the outer cortex form the surface layers of peanut (Arachis hypogaea) roots, the outermost of which separate and shed from the periphery. Shedding takes place continuously and over the whole surface of the root. Light and electron microscopic studies revealed that the shedding of surface layers involves modification of cell walls and separation of intact cells. Wall breakdown, as well as the expansion of cells resulting from wall breakdown, might facilitate the separation of intact cells. Examination of enzymes revealed that cellulase showed much higher activity in the shedding layers than in the remaining tissues. The results suggest that the cell separation process in peanut roots involves a wall-degrading enzyme-mediated mechanism. Key words: Arachis hypogaea, morphology, root, shedding, surface layers, wall breakdown.

Comments on collision mechanics in ring systems

1984 ◽  
Vol 75 ◽  
pp. 407-422
Author(s):  
William K. Hartmann
Keyword(s):  
Asteroid Belt ◽  
Surface Erosion ◽  
Surface Layers ◽  
Ring Systems ◽  
Eclipse Observations ◽  
Saturn’S Rings ◽  
Saturn's Rings

ABSTRACTThe nature of collisions within ring systems is reviewed with emphasis on Saturn's rings. The particles may have coherent icy cores and less coherent granular or frosty surface layers, consistent with thermal eclipse observations. Present-day collisions of such ring particles do not cause catastrophic fragmentation of the particles, although some minor surface erosion and reaccretion is possible. Evolution by collisional fragmentation is thus not as important as in the asteroid belt.

Tumor Diagnosis

1982 ◽  
Vol 40 ◽  
pp. 262-265
Author(s):  
Bruce Mackay
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Differential Diagnosis ◽  
Light Microscopy ◽  
Clinical Examination ◽  
Ultrastructural Study ◽  
Diagnostic Procedures ◽  
Specific Diagnosis ◽  
Transmission Electron ◽  
Microscopic Diagnosis

The broadest application of transmission electron microscopy (EM) in diagnostic medicine is the identification of tumors that cannot be classified by routine light microscopy. EM is useful in the evaluation of approximately 10% of human neoplasms, but the extent of its contribution varies considerably. It may provide a specific diagnosis that can not be reached by other means, but in contrast, the information obtained from ultrastructural study of some 10% of tumors does not significantly add to that available from light microscopy. Most cases fall somewhere between these two extremes: EM may correct a light microscopic diagnosis, or serve to narrow a differential diagnosis by excluding some of the possibilities considered by light microscopy. It is particularly important to correlate the EM findings with data from light microscopy, clinical examination, and other diagnostic procedures.

Further Observations on the Virus of Epizootic Diarrhea of Infant Mice. An Electron Microscopic Study

1967 ◽  
Vol 25 ◽  
pp. 110-111
Author(s):  
W. G. Banfield ◽  
G. Kasnic ◽  
J. H. Blackwell
Keyword(s):  
Electron Microscope ◽  
Infected Cell ◽  
Microscopic Study ◽  
Intestinal Epithelium ◽  
Ultrastructural Study ◽  
Osmium Tetroxide ◽  
Lead Citrate ◽  
Electron Microscopic ◽  
Virus Particles ◽  
Infected Cells

An ultrastructural study of the intestinal epithelium of mice infected with the agent of epizootic diarrhea of infant mice (EDIM virus) was first performed by Adams and Kraft. We have extended their observations and have found developmental forms of the virus and associated structures not reported by them.Three-day-old NLM strain mice were infected with EDIM virus and killed 48 to 168 hours later. Specimens of bowel were fixed in glutaraldehyde, post fixed in osmium tetroxide and embedded in epon. Sections were stained with uranyl magnesium acetate followed by lead citrate and examined in an updated RCA EMU-3F electron microscope.The cells containing virus particles (infected) are at the tips of the villi and occur throughout the intestine from duodenum through colon. All developmental forms of the virus are present from 48 to 168 hours after infection. Figure 1 is of cells without virus particles and figure 2 is of an infected cell. The nucleus and cytoplasm of the infected cells appear clearer than the cells without virus particles.

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