Growth of a vanadium oxide layer on V(100) and its reactivity towards atomic hydrogen.

The influence of a surface oxide on V(100) on the sticking of atomic hydrogen was studied. The oxide was produced by dosing with oxygen at different surface temperatures and characterized by AES and XPS. Thermal desorption spectroscopy was used to determine the sticking coefficient of atomic hydrogen. The kinetics of oxidation and the stability of the formed oxide have been studied in detail. The highest oxidation rate was obtained at a surface temperature of 473 K, producing a V2O3 over-layer. Although the sticking coefficient for atomic hydrogen decreases from 0.14 on the oxide free V(100) surface to 0.015 on the V2O3 surface, the sticking coefficient for atomic hydrogen was still several orders of magnitude higher than that for molecular hydrogen. This is relevant in respect of the use of the hydrogen-vanadium system for energy storage.

Immunohistochemical characterization of a differentiation-specific carbohydrate epitope in the plasma membrane of the epithelial cells of rat small intestine.

The monoclonal antibody (MAb) SI/EC1 was produced by immunization of Balb/c mice with an antigen prepared from the isolated basolateral membrane (BLM) of rat small intestine epithelial cells by trypsin cleavage. Immunohistochemical labeling at the light and electron microscopic level shows that the SI/EC1 epitope is localized in the plasma membrane (PM) of the small intestine epithelial cells and is expressed around Day 21 after birth (weaning time). There are, however, differences in the labeling between crypt and villous cells. In the crypt cells, the microvillous membrane (MVM) and the lateral part of the BLM are strongly labeled, whereas the basal part of the BLM is unlabeled. In the villous cells, both the MVM and the basal and lateral part of the BLM are labeled, but the labeling is not as intense as in the crypts. In immunoblotting experiments with the isolated BLM, three protein bands (125 KD, 110 KD, and 90 KD) were labeled specifically with the MAb. Enzymic cleaving of the BLM with exo- and endoglycosidases and subsequent immunoblotting, as well as other findings, suggest that the specific structure of the SI/EC1 epitope consists mainly of carbohydrates (CH) (oligosaccharides). This finding points out the possibility that this epitope may have something to do with the variable adhesion of the small intestine epithelial cells along the crypt-villus axis.

Immunohistochemical characterization of a crypt cell-specific plasma membrane protein in rat small intestine epithelium using a monoclonal antibody.

Proteins of the basolateral membrane (BLM) of small intestine epithelial cells of adult rats, in the MW ranges of 50-65 KD, 85-100 KD, and over 100 KD, were obtained as follows. After isolation of the BLM and subsequent SDS-PAGE and transblotting of the proteins on nitrocellulose sheets, the bands in these MW ranges were cut out of the nitrocellulose sheet and extracted. Balb/C mice were immunized with these protein fractions and a monoclonal antibody (MAb) was then produced. MAb SI/CC1 obtained via immunization with the 50-65 KD protein fraction shows specificity for the crypt epithelium of the small intestine. It can be used to characterize, by light and electron microscopic immunohistochemical methods, a crypt cell protein (SI/CC1-Ag) with a very specific localization. Fluorescence labeling shows that the SI/CC1-Ag can be found only in the epithelium of small intestine crypts (except for the granules in eosinophilic granulocytes). The epithelium of the colon, as well as the epithelia of other organs, could not be labeled. In the small intestine crypts, SI/CC1-Ag is found only in the Paneth cells located in the basal crypt section, and in the undifferentiated cells in the middle crypt section; it is lacking in the cells of the upper crypt section. Gold labeling shows that SI/CC1-Ag in the undifferentiated cells is localized exclusively in the basolateral PM domain. On the Paneth cells, the content of the secretory granules is labeled, along with the basolateral PM domain; the labeling sometimes present on their luminal part is probably due to passively absorbed secretion from these cells. The SI/CC1-Ag in the BLM of undifferentiated and Paneth cells is found only on Days 21-23 post partum, whereas the Paneth cell granules could be labeled as early as the Day 16 post partum. With immunodetection with SI/CC1, one band at about 55 KD is specifically labeled in the protein pattern of the isolated small intestine cell BLM. In the protein pattern of the isolated crypt cells two bands were labeled, again one at 55 KD and one at about 120 KD. These findings indicate that SI/CC1-Ag is a 55 KD protein that appears on Days 21-23 post partum in the BLM of undifferentiated cells and of Paneth cells.

N-terminal amino acid sequence, immunohistochemical localization and tissue distribution of a plasma membrane protein (Prot17) of rat enterocytes.

Prot17, a protein of the basolateral membrane of rat small intestine with a mol.wt. of 17 kDa, can be isolated using a previously described method (Schiechl 1988). It occurs in the membrane as an oligomer with a mol.wt. of 90 kDa. In the present study a polyclonal antibody specific for Prot17 was used to explore by immunohistochemical techniques the tissue distribution of Prot17 and its ultrastructural localization within the cells. Furthermore the amino acid sequence of the N-terminal part of this molecule up to position 17 could be analyzed. The results are summarized as follows: Prot17 is a membrane anchored protein. Its partial amino acid sequence suggests that it is neither identical nor related to other known proteins. Immunofluorescence studies revealed, that it occurs only in epithelial cells. It is mainly found in the absorptive and goblet cells of the intestine and the acinar cells of the pancreas. Smaller quantities are found also in the bile duct epithelium of the liver, in the proximal tubule cells of the kidney and in the cells of the respiratory epithelium. Ultrastructural localization of Prot17 was possible in the intestinal epithelium and pancreas acinar cells. In both cell types it was found in the basolateral and microvillous membrane. In pancreas, Prot17 was also detected in the membrane of the zymogen granules. In the absorptive cells of the intestine Prot17 was found in both the membrane and the contents of subluminal vesicles. Furthermore, in apical granules of secretory cells of the respiratory epithelium binding of Prot17 specific antibody was found in the granular content, the membrane being negative.

Immunohistochemical detection of an epithelial membrane protein in rat embryos at different stages of development.

This study aimed to describe the distribution of a membrane protein called Gz-1-Ag in embryonal rat tissues using monoclonal antibodies. Three monoclonal antibodies recognizing different antigenic determinants of Gz-1-Ag were tested on different stages of rat embryos-fertilized oocytes, two-cell stages, morulae, blastocysts and embryos up to 17.5 days old. The embryos were fixed by different methods; the Tokuyasu method was the most convenient. It yielded very good morphological conservation, good preservation of antigenicity and weak background fluorescence. Gz-1-Ag was detected in practically all early epithelial structures, but the intensity of fluorescence varied. Fluorescence was not associated with the germ layer from which the epithelium derived. The uninterrupted presence of Gz-1-Ag from the fertilized oocyte to all subsequently arising epithelial structures suggests a role of Gz-1-Ag in cell adhesion, secretory processes or the intercellular exchange of information or substances.

Isolation, chemical characterization, and immunohistochemical localization of a protein from the basolateral plasma membrane of the rat intestinal absorptive cell.

The protein pattern of the basolateral membrane (BLM) of the rat small intestinal absorptive cell shows about 20 major and a multitude of minor bands. A simple and efficient method is described for isolation and purification of a major protein in the 17 kDa molecular weight (MW)-range called Prot 17. The isolated BLM of intestinal epithelial cells was dissolved in buffer 1 (Tris/HCl, 2% SDS, 10% glycerol, 5% beta-mercaptoethanol, pH 6.8) and subsequently dialyzed for 4 h against buffer 2 (Tris/glycine, pH 8.3) and then for 12 h against buffer 2 containing 25% methanol. The resulting precipitate contained Prot 17 and phospholipids in the form of liposomes. All other BLM proteins remained dissolved in the supernatant. Chemical characterization of Prot 17 suggested that it is an integral membrane protein amounting to about 5% of the total BLM protein. Amino acid analysis revealed a MW of 17.6 kDa. The Prot 17 molecule did not contain any PAS-positive carbohydrates. In its isolated form, and apparently also in the BLM, Prot 17 occurred as a polymerized structure with a MW of about 90 kDa. By dissolution in buffer 1 and heating to 100 degrees C for 1 min the complex was split into its 17 kDa subunits. By oxidation with performic acid it was also broken down into its subunits. A specific antiserum against Prot 17 was obtained from immunized Balb/c mice. Immunofluorescence labelling of rat small intestinal sections with this serum showed that Prot 17 was not a BLM-specific protein. It occurred in both plasma membrane domains of the intestinal absorptive cell.

Different antigen expression on Wolffian and Müllerian cells in rat embryos as detected by monoclonal antibodies.

The Wolffian duct and the developing Müllerian duct of 14 and 15 day old rat embryos were examined with the monoclonal antibodies GZ1 and GZ2. These antibodies react with antigens situated in the cell membrane of Wolffian cells; they do not react with Müllerian cells. This different antigen expression confirms the current opinion that these cells are of different types. A cellular contribution from the Wolffian duct to the developing Müllerian duct was not found.

Immunohistochemical studies of the distribution of a basolateral-membrane protein in intestinal epithelial cells (GZ1-Ag) in rats using monoclonal antibodies.

The monoclonal antibody (mAb), GZ1, is specific for a 42-kilodalton (kD) protein (designated GZ1-Ag) present among the plasma membrane (PM) proteins of the absorptive cells of rat intestine. This protein only occurs in the basolateral PM and is absent from the microvillus membrane. GZ2 and GZ20 are two other mAbs that are also directed against GZ1-Ag but which specify other antigenic determinants of this protein than mAb GZ1. Used together, these three mAbs allow better characterization of GZ1-Ag and more precise investigation of its distribution and localization in various rat cells. We performed immunohistochemical labelling for GZ1-Ag at both the light- and electron-microscope levels and found that GZ1-Ag is extensively distributed in rat epithelial tissues. However, the amount of this protein present in epithelial tissue shows considerable variation. GZ1-Ag is not present in the secretory cells of terminal portions of most excretory glands or in cells of the endocrine glands and liver. The cells of kidney tubules, except for collecting tubules, also lack GZ1-Ag. Only small amounts of GZ1-Ag are present in the cells of the stratified squamous epithelium and transitional epithelium, the exception being superficial cells. High concentrations of GZ1-Ag occur in the excretory duct systems of glands and in the various kinds of epithelium present in the male and female genital tract. Our results also indicated that the GZ1-Ag in all of these cells has a very similar structure.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistochemical localization and characterization of a protein from the basolateral membrane of rat small intestine epithelium using monoclonal antibody GZ-1.

The proteins of the basolateral membrane (BLM) of small intestine epithelial cell in rat have been less precisely described than those of the microvillus membrane (MVM). To identify BLM-specific proteins, Balb/c mice were immunized with isolated intestinal epithelial cells and monoclonal antibodies (MAb) to their cell membrane, produced with the hybridoma technique. One of the MAb so obtained (GZ-1), a class 1 IgG, is specifically directed to a surface membrane protein of intestinal epithelium (GZ-1-Ag). The MAb served to characterize the protein as follows. Light microscopic immunohistochemical FITC labeling and, still more clearly, electron microscopic labeling with colloidal gold on Lowicryl sections of small intestinal tissue, show that the GZ-1-Ag occurs only in BLM of the absorptive cell and the goblet cell. It is not present in the MVM, the tight-junction area, and probably in the desmosomal sections of the membrane. The crypt cells are more markedly labeled with GZ-1 than are the villus cells; the villus cells are also more clearly labeled from the duodenum to the ileum. Gross analysis of the position of the gold marker on the BLM indicates that GZ-1-Ag is probably integrated into the lipid bilayer. With immunoblotting (with HRP as marker), a single band of MW 42,000 D can be identified as the corresponding GZ-1-Ag from the protein band pattern obtained with SDS-PAGE from BLM isolated in the presence of protease inhibitors (PI). In BLM fractions isolated without protease inhibition, a band of MW 30,000 D can be labeled with GZ-1. These results are interpreted as follows: GZ-1-Ag is a protein of MW 42,000 D. On isolation of the BLM without PI, a piece of this protein is broken off by proteolysis. The larger piece of the molecule (30,000 D) is not accessible to the proteolytic enzyme owing to its localization in the BLM, and therefore remains intact (and recognizable by the Ab). The preferred position of the gold marker on the BLM is in agreement with this explanation.

[Changes in basolateral membrane of villus cells in the rat small intestine at low pH]. / Veränderungen der basolateralen Membran der Saumzellen des Rattendünndarmes bei niedrigem pH.

The basolateral membrane of isolated villus cells of rat small intestine was isolated and was used to investigate the structural changes as well as the simultaneous alterations of its protein pattern at low pH-value. For this purpose the alterations, which occur on the membrane under the influence of HCL, were studied in the electron microscope (negative staining) and by SDS-Polyacryl-amid-Gel electrophoresis. The results show firstly a total disintegration of the membrane and the formation of very uniformly shaped fragments and secondly the absence of protein bands in the fragments in comparison to the protein pattern of the intact membrane. Extraction of more extensive protein bands could not be demonstrated. Possible conclusions concerning the structure of the basolateral membrane and parallels to the reaction of Erythrocyte membrane under the same conditions are discussed.

The growth of follicles in the rat ovary under the influence of busulphan and endoxan.

Busulphan and Endoxan inhibit the normal course of ovarian follicular growth. Older secondary as well as an antral follicles perish within a very short time. Growing follicles, which at the beginning of the experiment exhibited only one layer, remained intact and single-layered during the entire duration of the experiment. The oocytes, however, continue growing, and the cytoplasmic structures, which are characteristic of older growing follicles, develop in them as well as in the follicle cells. Even a theca formation develops. In some of the "growing" follicles which have remained single-layered, after 10 days of Busulphan administration, some liquor folliculi is produced and accumulates in a fissure-shaped "antrum" between the zona pellucida and the follicular epithelium.

[Preparative isolation of protein III of the human erythrocyte membrane (author's transl)]. / Präparative Isolierung des Protein III der meschlichen Erythrocytenmembran

The paper describes a method for the large-scale isolation of protein III (protein E, major intrinsic protein) from the human erythrocyte membrane with little expenditure of time. By treatment of the erythrocyte ghosts with deluted HCl at pH 2.3 and 0 degrees C some membrane proteins can be extracted. From the remaining "rest" membranes, whose major constituents, besides phospholipides, are protein PAS-1, other carbohydrate containing proteins and protein III, the latter can be separated in pure form by means of gel filtration. The paper reports on the amount, purity and possible structural modifications of the protein III obtained by this isolation method.

[Light and electron microscopic studies of nucleus-like formations of fragmented oocytes in rat ovary]. / Licht- und elektronenmikroskopische Untersuchungen an den Scheinkernen fragmentierter Eizellen im Rattenovar

Oocytes in ovarian atretic follicles now and then show in their cytoplasm nucleuslike formations. The appearance of those pseudonuclei in the rat is described by light-and electron microscopy. Every pseudonucleus contains one or more Feulgen positive particles, and is surrounded by a membrane on its surface. The pseudonuclei are formed in the course of degeration of the oocyte during 1. und 2. meiotic metaphase from contracted chromosomes, probably with the involvement of the mixoplasma.