Distribution of surface coat material on fusing neural folds of mouse embryos during neurulation

1978 ◽  
Vol 191 (3) ◽  
pp. 345-349 ◽  
Author(s):  
T. W. Sadler
Keyword(s):  
Mouse Embryos ◽  
Surface Coat ◽  
Coat Material

The surface coat of infective larvae of Trichinella spiralis

Parasitology ◽  
1999 ◽  
Vol 118 (5) ◽  
pp. 509-522 ◽  
Author(s):  
J. MODHA ◽  
M. C. ROBERTS ◽  
W. M. ROBERTSON ◽  
G. SWEETMAN ◽  
K. A. POWELL ◽  
...  
Keyword(s):  
Trichinella Spiralis ◽  
Amorphous Material ◽  
Protein S ◽  
Datura Stramonium ◽  
Metabolic Energy ◽  
Surface Coat ◽  
Microscopical Examination ◽  
Infective Larvae ◽  
Coat Material ◽  
Pronase Treatment

The surface coat of the infective larvae of the parasitic nematode Trichinella spiralis was characterized with respect to its biophysical properties, morphology and composition. Labelling of larvae with the fluorescent surface probe PKH26 was lost after activation (by incubation in mammalian medium containing trypsin and bile), or following pronase treatment. Electron microscopical examination revealed that pronase treatment resulted in the loss of an amorphous surface layer only, further demonstrating the specificity of PKH26 for the larval surface coat. Surface coat shedding was inhibited by sodium azide and carbonyl cyanide, or by incubation of larvae at 4°C, suggesting the shedding process required metabolic energy. Pre-labelled, unactivated larvae demonstrated continuous slow surface coat shedding and could be re-labelled with PKH26, indicating that the shed coat is replaced in these parasites. However, pre-labelled larvae which were activated failed to re-label with the probe, suggesting that activation provides an irreversible trigger for surface changes. PKH26, therefore, is a useful marker for larval activation. Examination of the shed coat material by scanning electron microscopy revealed 2 types of morphologies; one comprising thin multilaminate sheets and the other of amorphous material with ridges producing a fingerprint-like motif. Western- and lectin-blotting of the shed coat material demonstrated 2 prominent entities; a 90 kDa glycoprotein, which bound Datura stramonium agglutinin and was resistant to N- and O-glycanase treatment and a 47–60 kDa set of protein(s). Analysis of the surface lipids by electrospray mass spectometry revealed the presence of lysophosphatidic acid (lysoPA, C14[ratio ]2) and an unidentifiable component of 339·4 Da. These two lipids constituted 36·9% and 36% by mass of surface coat lipids respectively. The presence of lysoPA was confirmed by thin layer chromatography, which also detected phosphatidic acid (PA). The polar lipids detected in solvent rinses of intact parasites by electrospray mass spectrometry were PI (C48[ratio ]4), PE (C40[ratio ]4 and C38[ratio ]4), PS (C40[ratio ]4), lysoPC (C20[ratio ]2 and C18[ratio ]2) and lysoPA (C14[ratio ]2). These observations are discussed with respect to the role of the surface coat and its shedding in the T. spiralis host–parasite relationship.

scholarly journals An ultrastructural examination of the role of cell membrane surface coat material during neurulation.

1975 ◽  
Vol 64 (1) ◽  
pp. 172-181 ◽  
Author(s):  
D Moran ◽  
R W Rice
Keyword(s):  
Neural Tube ◽  
Membrane Surface ◽  
Progressive Increase ◽  
Cellular Migration ◽  
Surface Coat ◽  
Positive Material ◽  
Specific Distribution ◽  
Lateral Ridge ◽  
Coat Material

Data from neural crest cultures indicate that cell surface coat material (CSM) is directly involved in cellular migration and events surrounding differentiation. To investigate whether the CSM also has a morphogenetic role, embryos of the amphibian Ambystoma maculatum were examined ultrastructurally throughout the stages of neurulation. Segments of the neural axis were fixed in glutaraldehyde-containing Alcian blue 8GX, which reportedly enhances preservation of CSM, and were postfixed in OsO4 containing 1 percent lanthanum nitrate, which stains the CSM. The medial groove formed by the appearance of the neural ridges contains a large amount of CSM and numerous vesicles coated with lanthanum-positive material. In contrast, the lateral ridge surfaces are covered by a small amount of uniformly distributed CSM and a paucity of vesicles. As the ridges begin to fold there is a progressive increase in the amount of CSM within the presumptive neural tube region. Further convergence of the neural folds is accompanied by an increase of CSM at their leading edges. As the folds approximate each other, lanthanum-positive material physically bridges the gap. However, as the apposing tissue actually abuts to form the neural tube, no CSM is observed in the remaining interspace. The specific distribution and sequential accumulation of cell CSM during the events of neurulation strongly suggest its direct participation in the morphogenetic process.

scholarly journals Fibonectin is a component of the surface coat of human neutrophils

1981 ◽  
Vol 50 (1) ◽  
pp. 315-327
Author(s):  
S.T. Hoffstein ◽  
G. Weissmann ◽  
E. Pearlstein
Keyword(s):  
Cell Surface ◽  
Indirect Immunofluorescence ◽  
Neutrophil Function ◽  
Human Neutrophils ◽  
Surface Coat ◽  
Surface Material ◽  
Surface Distribution ◽  
Alpha 1 Antitrypsin ◽  
Covalently Linked ◽  
Coat Material

Although adherence to surfaces is central to neutrophil function many of the determinants of neutrophil adherence are still unknown. The possible involvement of cell surface material, fibronectin in particular, was therefore studied. Surface coat material was visualized ultrastructurally by the ferrocyanide—reduced osmium technique of Karnovsky (1971). Loosely attached surface coat material was seen distributed uniformly on cells in suspension. Indirect immunofluorescence indicated the presence of fibronectin on the neutrophil surface. Distribution of fibronectin as determined by indirect immunoferritin localization corresponded with the distribution of cell coat material. Some, if not all, of this fibronectin was synthesized by neutrophils themselves since metabolically labelled fibronectin could be obtained by immunoprecipitation after short-term culture with [36S]methionine. Neutrophils also adhere to Sepharose beads to which gelatin is covalently linked (GS) but not to plain Sepharose beads (PS). In the process they transfer surface coat material to GS but not PS. Similar transfer was seen when cells were permitted to adhere to glass or plastic coverslips. Indirect immunofluorescence showed that fibronectin-containing material was transferred from neutrophils to GS but not PS. Parallel studies with antisera to 2 other plasma proteins, factor VIIIR and alpha 1-antitrypsin showed that neutrophils did not transfer these to either GS or PS beads. The data suggest that material antigenically and functionally related to fibronectin is associated with the extracellular coat of neutrophils and is transferred with cell surface material to surfaces to which neutrophils adhere.

Surface coat material associated with the developing otic placode/vesicle in the chick

1988 ◽  
Vol 220 (2) ◽  
pp. 198-207 ◽  
Author(s):  
Allan R. Sinning ◽  
Mark D. Olson
Keyword(s):  
Surface Coat ◽  
Otic Placode ◽  
Coat Material

Changes in the surface coat of mesenchymal cells of mouse limb buds after enzymatic cell separation

Development ◽  
1980 ◽  
Vol 59 (1) ◽  
pp. 145-155
Author(s):  
Evamaria Kohnert-Stavenhagen ◽  
Bernd Zimmermann
Keyword(s):  
Surface Layer ◽  
Cell Separation ◽  
Mesenchymal Cells ◽  
Ruthenium Red ◽  
Mouse Embryos ◽  
Surface Coat ◽  
Limb Buds ◽  
Partial Separation ◽  
Collagenase Treatment ◽  
Mouse Limb

Isolation of cells is nowadays performed by enzymatic means. The influence of such enzymes on the surface coat of mesenchymal and blastemal cells during the dissociation of limb buds from 11 -day-old mouse embryos was studied electron microscopically after staining with ruthenium red. EGTA or collagenase failed to bring about cell separation. The surface coat seemed to be unchanged after collagenase treatment. After EGTA an increase in extracellular filaments was observed. The proteases α-chymotrypsin, dispase II, papain, pronase P and trypsin (0·2%, 37 °C, 20 min) succeeded in completely dissociating limb buds. Apart from single granules, there was a detachment of the surface coat from the cells in all cases studied. Hyaluronidase led to only partial separation, but the detachment of the surface coat was almost complete, indicating a GAG-rich surface layer on these cells.

scholarly journals Activation for cell fusion in Chlamydomonas: analysis of wild-type gametes and nonfusing mutants.

1982 ◽  
Vol 92 (2) ◽  
pp. 378-386 ◽  
Author(s):  
U W Goodenough ◽  
P A Detmers ◽  
C Hwang
Keyword(s):  
Cell Fusion ◽  
Mating Type ◽  
Central Zone ◽  
Uranyl Acetate ◽  
Surface Coat ◽  
Wild Type ◽  
En Bloc ◽  
Mating Structure ◽  
Fusion Images ◽  
Coat Material

Gametes of Chlamydomonas reinhardi become activated for cell fusion as the consequence of sexual adhesion between membranes of mating-type plus and minus flagella. By using tannic acid plus en bloc uranyl acetate staining, and by fixing at very early stages in the mating reaction, we have demonstrated the following. (a) Activation of the minus mating structure entails major modifications in the structure of the organelle, causing it to double in size and to concentrate surface coat material, termed fringe, into a central zone. (b) The unactivated plus mating structure is endowed with fringe that moves with the tip of the actin-filled fertilization tubule during activation. Pre-fusion images suggest the occurrence of a specific recognition event between the plus and minus fringes. (c) Gametes carrying the imp-1 mutation fail to form a fringe and are unable to fuse. The imp-1 mutation is linked to the mating-type plus (mt+) locus, suggesting that the gene specifying the synthesis or insertion of fringe is encoded in this sector of the genome. (d) Gametes carrying the imp-11 mutation fail to form both a normal fringe and a normal submembranous density beneath the fringe, and are also unable to fuse. The imp-11 mutation converted a wild-type minus cell into a pseudo-plus strain; a model to explain this conversion proposes that the normal imp-11 gene product represses plus-specific genes concerned with Chlamydomonas gametogenesis.

Visualization of the Platelet-Plasma Interface

1977 ◽  
Vol 35 ◽  
pp. 494-495
Author(s):  
D. C. Brindley ◽  
M. McGill
Keyword(s):  
Platelet Rich Plasma ◽  
Coagulation Factors ◽  
Platelet Membrane ◽  
Rabbit Platelet ◽  
Surface Coat ◽  
Special Relationship ◽  
Routine Method ◽  
Embedding Technique ◽  
Biochemical Analyses ◽  
Adsorptive Properties

Morphological and cytochemical studies of platelets have reported a surface coat, or glycocalyx, external to the plasma membrane (1). Biochemical analyses have likewise confirmed the highly adsorptive properties of platelets as transporters of coagulation factors (2). However, visualization of the platelet membrane by conventional EM procedures does not reflect this special relationship between the platelet and its plasma environment. By the routine method of alcohol-propylene oxide dehydration for Epon embedding, the lipid bilayer nature of the platelet membrane appears similar to other blood cells (Fig. 1). A new rapid embedding technique using dimethoxypropane (DMP) as dehydrating agent (13) has permitted ultrastructural analyses of the surface features of the platelet-plasma interface.Aliquots of human or rabbit platelet-rich plasma (PRP) were added to equal volumes of 6% glutaraldehyde in Millonig's buffer at 37° for 45 minutes, rinsed in buffer and postfixed in 1% osmium in Millonig's buffer for 45 minutes.

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