bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunocytochemistry of plant defense mechanisms induced upon microbial attack
Authors: Benhamou Nicole 
Published: February 2005

AbstractDuring the past few years, cyto‐ and immunocytochemical techniques have been developed and widely used for locating and identifying various molecules in plant cell compartments. The last decade has witnessed tremendous improvements in molecular cytology, thus allowing an accurate in situ detection of various components thought to play important biological functions in the plant metabolism. The use of immunocytochemistry to investigate resistance mechanisms of plants upon pathogen attack has provided key information on the defense strategy that plants elaborate during a host‐pathogen interaction. Of the various proteins induced in response to infection, chitinases and β‐1,3‐glucanases have been the focus of particular attention due to their believed antimicrobial activity through the hydrolysis of the main fungal wall components, chitin and β‐1,3‐glucans. Attention has also been paid to β‐fructosidase, the enzyme that hydrolyzes sucrose into glucose and fructoside. The marked accumulation of this enzyme upon pathogen infection has led to the consideration that infection may greatly infleunce the metabolic activity of colonized tissues by creating alterations of source‐sink relationships. Another facet of the plant's defense strategy that has been the focus of considerable interest is related to the accumulation of structural compounds, such as hydroxyproline‐rich glycoproteins and callose, to reinforce the wall architecture, thus decreasing vulnerability to microbial enzymes. A number of alternatives designed to improve plant protection towards pathogen invasion have been suggested. Among these, the production of transgenic plants expressing constitutively a foreign resistance gene and the pretreatment of plants with elicitors of defense reactions have been the subject of intensive studies at the molecular, biochemical, and cytological levels. Results of such studies clearly demonstrate the important contribution that cyto‐ and immunocytochemical approaches can make to our knowledge of how plants defend themselves and how plant disease resistance can be directly enhanced. These approaches will undoubtedly be active areas for future research in the development of biological control alternatives in which the mode of action of the product used is of key importance. © 1995 Wiley‐Liss, Inc.
Immunogold localization of actin in the testis and exocrine pancreas: Spatial relationship with tight junctional strands
Authors: Kan Frederick W. K. , Lin Yan 
Published: February 2005

AbstractThe fracture‐label technique was used in conjunction with a monoclonal antibody to actin and the phospholipase A2‐colloidal gold (PLA2‐CG) method to examine the spatial distribution of actin filaments in relation to the three‐dimensional arrangement of tight junctional strands in rat testes and exocrine pancreatic acinar cells. The intimate association of actin filaments with tight junctional strands in the pancreas and testis was also illustrated by a doublelabeling experiment in which freeze‐fractured pancreas or testis was labeled with monoclonal antibody‐protein A‐gold (30 nm gold size) followed by incubation with a PLA2‐CG complex (11 nm gold size). Freeze‐fracture‐exposed tight junctional strands in both testicular and exocrine pancreatic cells labeled by PLA2‐CG complex indicated the presence of phospholipids in these cylindrical membranous structures. Immunolabeling of freeze‐fractured testes with a monoclonal antibody to actin revealed a narrow band of gold particles juxtaposed to the cytoplasmic aspect of the protoplasmic membrane halves decorated with parallel linear arrays of cylindrical tight junctional strands. Many of the gold particles representing actin antigenic sites were in direct contact with the cross‐fractured tight junctional strands. Fracture‐label preparations of exocrine pancreas labeled with the monoclonal anti‐actin antibody also exhibited a similar labeling pattern at the apex of acinars cells where the tight junction complex is located. Double‐labeling experiments revealed the simultaneous labeling of actin and phospholipids in the same fracture‐label preparations. Digestion of testicular and pancreatic tissue samples in a free PLA2 solution prior to labeling with the monoclonal antibody or PLA2‐CG complex removed not only the gold labeling previously seen over the tight junctional strands but also reduced drastically the immunolabeling for actin that was previously seen associated with the tight junction complex. Taken together, results of the present study showed that actin filaments are structural components of the tight junction strands and are connected to the cytoplasmic aspect of the latter structures. The interaction between this particular cytoskeletal element and the tight junction may be through the binding of a special domain of the actin filament to the phospholipids that partially make up the tight junctional complex. © 1995 Wiley‐Liss, Inc.
Morphological studies of the developing human esophageal epithelium
Authors: Ménard Daniel 
Published: February 2005

AbstractThis article focusses on the structural development of human esophageal ciliated epithelium. A combination of transmission electron microscopic (TEM), scanning electron micro‐scopic (SEM), radioautographic, and light microscopic (LM) analyses were carried out using intact fetal tissues between 8 and 20 weeks of gestation as well as cultured esophageal explants. Up to the age of 10 weeks, the stratified esophageal epithelium consisted of two longitudinal primary folds. The surface cells were undifferentiated and contained large glycogen aggregates. Between 11 and 16 weeks, the primary folds (now up to four) had developed secondary folds. The thickness of the epithelium drastically increased (123%) in concomittance with a differentiation of surface columnar ciliated cells. These highly specialized surface cells exhibited junctional complexes and well‐developed organelles with numerous microvilli interspesed among the cilia. Transverse sections revealed the internal structure of the cilia with a consistent pattern of nine doublet microtubules surrounding a central pair of single microtubules. Freeze‐fracture studies illustrated the presence of a ciliary necklace composed of 6 ring‐like rows of intramembranous particles. They also revealed the structure of ciliary cell tight junctions consisting of up to nine anastomosing strands (P‐face) or complementary grooves (E‐face). Ultrastructural studies (LM, TEM, SEM) of the esophageal squamous epithelium obtained after 15 days of culture showed that the newly formed epithelium was similar to adult human epithelium. Finally LM and SEM observations established that the esophagogastric junction was not yet well delineated, consisting of a transitional area composed of a mixture of esophageal ciliated cells and gastric columnar mucous cells. © 1995 Wiley‐Liss, Inc.
Freeze‐fracture and immunohistochemical studies of gap junctions in human gastric mucosa with special reference to their relationship to gastric ulcer and gastric carcinoma
Authors: Ohkusa T. , Fujiki K. , Tamura Y. , Yamamoto M. , Kyoi T. 
Published: February 2005

AbstractOur aim was to determine whether the development of gap junctions in the human gastric mucosa has any relation to gastric ulcer and gastric carcinoma. Freeze‐fracture replicas were prepared from the endoscopic biopsy specimens of 20 patients with gastric ulcer and 7 healthy volunteers. Large fractured areas of lateral cell membranes of surface mucous cells were examined randomly under an electron microscope. Small gap junctions were observed between gastric surface mucous cells in all healthy volunteers. Gap junctions in the patients with gastric ulcer were significantly fewer than in the healthy volunteers. In addition, gap junctions in patients with recurrent ulcer were significantly fewer than in those with first‐onset ulcer. There was no obvious relationship between age and the development of gap junctions in patients with gastric ulcer or in healthy volunteers. In the areas of intestinal metaplasia, gap junctions were occasionally seen between absorptive cells of the villi, but not in the lateral membranes of goblet cells. Fresh frozen sections for indirect immunofluorescence were prepared from the endoscopic biopsy specimens of 19 patients with gastric ulcer and 5 patients with gastric cancer. Monoclonal antibody against liver gap junction protein (anti‐connexin 32, 6–3G11) was used for the indirect immunofluorescence. On the border of gastric ulcer, fluorescent spots in the surface mucous cells were significantly fewer than in the surface mucous cells of the body and antrum which were distant from the ulcer area in the same patients. In gastric cancer tissue specimens, fluorescent spots were not observed at all. On the other hand, fluorescent spots in the noncancerous tissue of the patients with gastric cancer were present along the intercellular junctions between gastric surface mucous cells. These findings suggest that loss of intercellular communication via gap junctions is associated with gastric ulcer formation and gastric cancer formation. © 1995 Wiley‐Liss, Inc.
Ultramicrotomy of nanocrystalline materials
Authors: McMahon G. , Malis T. 
Published: February 2005

AbstractThe methodology and one of the first attempts to produce transmission electron microscopic (TEM) specimens of nanocrystalline metals, alloys and ceramics by ultramicrotomy are presented. Samples of the pure elements Co, Pd; alloys of Y‐12 at.% Fe, Al‐7 at.% Ag and W‐30 at.% Ga; and ZnO ceramic, were found to section successfully to varying degrees. Advantages of sections prepared through ultramicrotomy over ion beam methods include extensive electron‐transparent regions of uniform thickness and absence of ion beam damage. Typical artefacts were observed (knife marks, tearing, pull‐out, shear lamellae, section curling, and anodic dissolution) but did not impede TEM analysis significantly. A potentially important effect observed was that of a texture development upon sectioning of the Co and Pd samples. It is thought that this unusual phenomenon results from the extremely fine scale of the microstructure and the purity of the Co and Pd samples, and may be enhanced by frictional heating effects and the state of the knife edge. © 1995 Government of Canada.Exclusive worldwide publication
rights in the article have been transferred to Wiley‐Liss, Inc., in perpetuity.
Electrochemical and microstructural study of oxide films formed electrochemically at microcrystalline al‐fe‐v‐si alloys
Authors: Thomas S. C. , Birss V. I. , Steele D. , Tessier D. 
Published: February 2005

AbstractA recent advance in metallurgical technology has been the application of rapid solidification techniques to Al alloy production. FVS0812 is the designation given to a microcrystalline Al‐based alloy consisting of 8 wt% Fe, 1 wt% V and 2 wt% Si. It is a two‐phase alloy, consisting of ca. 27 vol percent of approximately spherical Fe‐V‐Si‐rich dispersoids in an essentially pure Al matrix. The high strength, low density properties of this advanced material, and other related alloys, have not yet been realized, however, due, in part, to the inability of the alloy to form a thick, adherent, abrasion‐resistant outer surface oxide film, a feature readily achieved at conventional Al alloys by normal anodizing methods. The present research has involved an electro‐chemical study of oxide film growth at the 812 alloy, with the specific goals being to seek an understanding of the origin of the oxide film growth problem and ultimately to propose alternative approaches to the formation of a thick, stable oxide film at this material. The techniques used in this research have included electrochemical methodologies such as cyclic voltammetry and electrochemical impedance spectroscopy. Crucial information has been obtained through transmission electron microscopy (TEM) of ultramicrotomed specimens. Experiments were carried out initially in neutral borate solutions to characterize the compact barrier oxide film formed in this environment and expected to be present beneath the porous oxide film formed in the normal sulfuric acid anodizing medium. In borate solutions, the electrochemical results implied oxide film thicknesses which were less than seen subsequently by TEM work, suggesting either that the barrier film at the 812 alloy can be penetrated by solution in very fine pores (not resolvable by conventional TEM) at its outer surface or that dispersoids trapped in the oxide film cause differential oxide film thicknesses to develop across the alloy surface. In sulfuric acid solutions, dissolution of Fe and V occurs from the 812 alloy during anodization. Both impedance and TEM studies reveal the absence of a barrier film at the 812 alloy surface. Also, the thick oxide overlayer has a tortuous and more open pore structure than formed at Al and the oxide film is also substantially thinner than it should be. It is suggested that the absence of a barrier oxide film indicates that the sulfuric acid anodizing medium is too aggressive for oxide film formation at the 812 alloy, resulting in excessive dissolution and poor oxide film qualities. © 1995 Wiley‐Liss, Inc.
Gap junctions in blood forming tissues
Authors: Rosendaal Martin 
Published: February 2005

AbstractMore than ten research groups have now reported the presence of gap junctions in blood‐forming tissue or cultured cells. It is time to accept that these cell‐coupling structures are present in this tissue. To find out what they are doing here we need to develop appropriate experimental techniques. This review covers the particular problems of investigating direct cell‐cell communication by gap or other junction in undisturbed haemopoietic tissue. It then describes and assesses the published reports of haemopoietic gap junctions. Recently, in the author's laboratory, three means of increasing the number of gap junctions 50‐ to 100‐fold in mouse marrow have been described, as well as techniques for doing so in culture. There is a complete report of this work here. At present it is quite unclear what function gap junctions serve in blood‐formation, perhaps it is some consolation that 30 years after their ultramicroscopic discovery it is also true for all other unexcitable tissues. Possibly the ability to up‐regulate their expression in haemopoietic tissue will help us find out what their role is in blood formation. © 1995 Wiley‐Liss, Inc.
Gap junctions revealed by freeze‐fracture electron microscopy
Authors: Shivers Richard R. , McVicar Lorne K. 
Published: February 2005

AbstractGap junctions provide the basis for the formation of elaborate networks of communication between cells in animal tissues. Electron microscopic examination of thin sections of plastic embedded gap junctions has provided valuable information on the anatomy and function of these remarkable structures. Freeze‐fracture electron microscopy, however, has made available unique vistas of gap junction‐bearing intramembrane surface–surface previously inaccessible to the researcher's eyes. Data on population density, distribution, size, geometry of intramembrane particle packing, and structural responses of gap junction components to experimental manipulation are simply and easily obtained with freeze fracture. Recent developments of sophisticated protocols of immunocytochemistry as applied to freeze‐fracture replicas further serve to reinforce the notion that freeze‐fracture is a powerful tool for study of gap junctions. Molecular techniques of gap junction gene transfection promise to add a truly unique dimension to investigations of the broad spectrum of functional roles of gap junctions. © 1995 Wiley‐Liss, Inc.
Electron microscopic image analysis of cardiac gap junction membrane crystals
Authors: Yeager Mark 
Published: February 2005

AbstractCardiac gap junctions play an important functional role in the myocardium by electrically coupling adjacent cells, thereby providing a low resistance pathway for cell‐to‐cell propagation of the action potential. Two‐dimensional crystallization of biochemically isolated rat ventricular gap junctions has been accomplished by an in situ method in which membrane suspensions are sequentially dialyzed against low concentrations of deoxycholate and dodecyl‐β‐D‐maltoside. Lipids are partially extracted without solubilizing the protein, and the increased protein concentration facilitates two‐dimensional crystallization in the native membrane environment. The two‐dimensional crystals have a nominal resolution of 16 Å and display plane group symmetry p6 with a = b = 85 Å and γ = 120°. Projection density maps show that the connexons in cardiac gap junctions are formed by a hexameric cluste rof α1 connexin subunits. Protease cleavage of α1 connexin from 43 to 30 kDa releases ∼13kDa from the carboxy‐tail, and the projection density maps are not significantly altered. Uranyl acetate stain penetrates the ion channel, whereas phospho‐tungstic acid is preferentially deposited over the lipid regions. This differential staining can be used to selectively probe the central channel of the connexon and the interface between the connexon and the lipid. The hexameric design of α1 connexons appears to be a recurring quaternary motif for the multigene family of gap junction proteins. © 1995 Wiley‐Liss, Inc.
Hormonal control of the biosynthesis of hamster oviductin
Authors: Malette Brigitte , Filion Benoit , St‐Jacques Sylvie , Kan Frederick W. K. , Bleau Gilles 
Published: February 2005

AbstractIn several mammalian species, the epithelial secretory cells of the oviduct synthesize and secrete specific glycoproteins that become associated with the zona pellucida of the ovulated oocyte. These glycoproteins are collectively designated as oviductins. A monoclonal antibody directed against hamster oviductin was used to study the ontogeny of this glycoprotein. Indirect immunofluorescence experiments performed on sections of hamster oviduct revealed that the glycoprotein begins to be secreted in 10‐day‐old females and that all of the oviductal secretory cells showed fluorescent staining by day 14. The intensity of the immunofluorescence reaction reached a maximum in the 28‐day‐old females. The oviducts of the 7‐day‐old hamster incorporated [35S]methionine in vitro into several proteins; however, the production and secretion of detectable amounts of radiolabeled oviductin only began at 14 days of age and reached a maximum at day 28 of age. It appears that the ontogeny of oviductin parallels the hormone dependent changes leading to sexual maturation and that its maximum secretion is already established at the time of the first ovulatory cycle. These results are substantiated by the fact that the production of oviductin is induced in estradiol‐treated, but not progesterone or non‐treated prepubertal animals, as determined by indirect immunofluorescence experiments. © 1995 Wiley‐Liss, Inc.
Isolation, cell culture, and characterization of oviduct epithelial cells of the cow
Authors: Joshi Madhusudan S. 
Published: February 2005

AbstractThis report describes an easy method of isolation and cell culture of the epithelial cells of cow oviduct. Incubation of cow oviduct with 0.1 mg/ml collagenase in the lumen for 90 minutes helped to dislodge large numbers of ciliated and secretory epithelial cells. The isolated cells, when seeded on plastic, proliferated very quickly and became confluent in 8–10 days in 35 mm Petri dishes. The isolated ciliated cells which attached to the plastic dish lost their cilia after 4–5 days in culture. The cultured epithelial cells were keretin positive. The isolated bovine oviduct epithelial cells, when cultured on plastic precoated with 10 mg/ml matrigel, organized themselves into hollow tubes or spheres with microvilli directed towards the lumen. The epithelial cells seeded on 2 mg/ml matrigel became subconfluent in 15–20 days after seeding. The histoarchitecture of the secretory cells growing in vitro on matrigel resembled that of intact oviduct secretory epithelial cells. Occasional ciliated cells containing large number of mitochondria were observed in the monolayer cultured on 2 mg/ml matrigel substratum but possessed few cilia. The oviduct epithelial cells cultured on 2 mg/ml matrigel incorporated 35S‐methionine linearily into protein up to 8 hours in the presence of estradiol or progesterone. The fluorograph of the newly synthesized proteins indicated the presence of an additional 60 kd protein in the cell extract of epithelial cells incubated with estradiol. © 1995 Wiley‐Liss, Inc.
Morphological study of changes in the baboon oviductal epithelium during the menstrual cycle
Authors: Louise Odor D. , Augustine James R. 
Published: February 2005

AbstractOviductal epithelium of the baboon, Papio cynocephalus, was studied utilizing light, scanning, and transmission electron microscopy. Results of counts made of nonciliated, ciliated, and ciliogenic cells were analyzed statistically. The percentages of nonciliated cells of the fimbria and ampulla during the early proliferative and late secretory stages of the menstrual cycle were significantly greater than those during the mid‐proliferative and late proliferative‐early secretory stages, due to deciliation. This paper emphasizes previously unreported apical surface morphology as viewed by scanning and transmission electron microscopy. The microvillar pattern of the fimbrial secretory cells differs from that of the ampullar and isthmic cells in that the microvilli originate from thick apical protrusions and vary greatly in length and number as related to the cycle. A ridge demarcating the apical intercellular junction is composed of rows of microvilli during the early proliferative and late secretory stages. During the early proliferative and late secretory stages an increased degree of invagination of the basal and lateral plasma membranes occurs as the height and width of the cells decreases. The general numbers and distribution of the organelles of the various types of oviductal cells agree with that described for the ampulla and isthmus by Verhage et al. [(1990) Am. J. Anat., 187:81–90]; however, fimbrial epithelium was not included in that study. Other cyclic ultrastructural changes not examined previously include variation in the number of lipid droplets and their location, and in the number and relationships of glycogen particles to other structures. © 1995 Wiley‐Liss, Inc.