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At least 433 records · Page 24Linked to original sources
PubMed1992

The effect of methotrexate (MTX) on the small intestine of the mouse. IV. The Golgi apparatus, phosphatases and esterases.

The Golgi apparatus and alkaline and acid phosphatase and nonspecific esterase activities were studied in the jejunal epithelium of adult male albino mice (Mus musculus) under normal conditions and after MTX treatment. In the control, the Golgi apparatus took the form of rods, spheres and crescents occupying the supranuclear region. After MTX, the Golgi apparatus, in most of the cells, was hypertrophied. In the control cells, alkaline and acid phosphatase and nonspecific esterase activities were moderate and localized supranuclearly, but were intense in the brush border and basement membrane. After MTX, all three enzyme activities increased, with a marked reaction in the brush border and basement membrane. The increase in alkaline phosphatase may mean that more phosphate transport is needed in the active phosphorylation process or in the transfer of MTX macromolecules across the cell membrane, or it may be due to MTX-induced disorganization of metabolism. The increase in acid phosphatase activity denotes an increase in catabolic processes resulting from imbalance of lysosomal function, while the rise in nonspecific esterase activity could be related to fatty acid metabolism, or it might be due to the detoxicant function of esterases. In all control and MTX-treated specimens, the supranuclear concentration of these enzymes coincided with the localization of the Golgi apparatus.

Animals↗
PubMed2003

The Golgi apparatus of satellite cells associated with spinal ganglion neurons: changes with age in the rabbit.

We studied the Golgi apparatus in the satellite cell sheaths enveloping spinal ganglion neurons of rabbits aged 12, 42, and 79 months. We found neither structural changes nor indications of peripheral displacement of this organelle with advancing age. The mean percentage of cytoplasmic volume occupied by the Golgi apparatus decreased significantly passing from young adult to old rabbits. This decrease was only in very minor part a consequence of lipofuscin accumulation, so that the ratio between the total volume of the Golgi apparatus and the functionally active volume of cytoplasm decreased with age. The mean cytoplasmic volume of perineuronal satellite cell sheaths did not change significantly with increasing age, whereas the total volume of the Golgi apparatus within these sheaths decreased significantly with age. This decrease strongly suggests that the activity of satellite cells diminishes in old age, further suggesting that these cells are unable to compensate for the decrease in the neuronal metabolism that a number of authors have described in old age.

Aging↗
PubMed1979

Lipoprotein secretion by rat liver Golgi apparatus. Lipoprotein particles and lipase activity.

Lipoprotein particles of the size range of very low density lipoproteins in smooth endoplasmic reticulum, peripheral elements of the Golgi apparatus, and secretory vesicles of the immature Golgi apparatus face are 55 to 80 nm in diameter. Particles in mature secretory vesicles are smaller (45 nm). Concomitant with the change in particle size, the lumina of mature vesicles increase in electron density. A technique to fractionate immature and mature secretory vesicles was based on precipitation of a cupric-ferrocyanide complex (Hatchett's brown) through the action of a NADH-ferricyanide oxido-reductase resistant to glutaraldehyde which is characteristic of the membranes of mature secretory vesicles and of the plasma membrane of liver. Mature secretory vesicle fractions so isolated were enriched in cholesterol and depleted in triglycerides relative to immature vesicles on a phospholipid basis. Lipase activity was present in secretory vesicle fractions of the Golgi apparatus as shown by biochemical analysis and by cytochemistry. Cytochemical studies showed lipase to be present in both mature and immature vesicles but most evident in immature vesicles. The findings suggest that some very low density lipoprotein particles are converted to particles of smaller diameter during transit through Golgi apparatus. A lipase-mediated hydrolysis of triglycerides may relate to the transformation.

Animals↗
PubMed1989

MG-160. A novel sialoglycoprotein of the medial cisternae of the Golgi apparatus [published eeratum appears in J Biol Chem 1989 Mar 5;264(7):4264].

A monoclonal antibody (mAb 10A8), derived from mice immunized with fractions of the Golgi apparatus from rat brain neurons, was exploited to isolate and partially characterize a novel glycoprotein of 160 kDa apparent molecular mass which was localized by immunoelectron microscopy in medial cisternae of the Golgi apparatus of neurons, glia, pituitary cells, and rat pheochromocytoma (PC 12). The yield of immunoaffinity purified protein was 0.9 microgram/g of rat brain and represented 3% of the Golgi protein; the protein contained asparagine-linked carbohydrates and sialic acid and N-acetylglucosamine residues; unreduced protein had a greater electrophoretic mobility (130 kDa) consistent with the presence of intrachain disulfide bonds. The bulk of the glycoprotein resided within the membrane and/or luminal face of the Golgi cisternae. After extraction with Triton X-114, the glycoprotein was found in both aqueous and detergent phases. The monoclonal antibody did not inhibit the activities of Golgi enzymes or the uptake of nucleotide sugars by intact Golgi vesicles. The findings indicate that the 160-kDa glycoprotein is a specific constituent of medial Golgi cisternae. The results of this study lend support to the hypothesis that the distributions of glycosyltransferases in the Golgi apparatus are cell specific, since in neurons this sialic acid containing glycoprotein is found in medial rather than in trans and/or in the trans Golgi reticulum cisternae, where sialyltransferases have been localized in other cells. Alternatively, resident neuronal Golgi sialoglycoproteins may acquire sialic acid in trans elements of the apparatus and then shuttle back in medial cisternae.

Adrenal Gland Neoplasms↗
PubMed1986

Differential subcompartmentation of terminal glycosylation in the Golgi apparatus of intestinal absorptive and goblet cells.

Two terminal glycosyltransferases, a sialyltransferase and the blood group A alpha 1,3 N-acetylgalactosaminyltransferase, were found to exhibit differential subcompartmentation in the Golgi apparatus of intestinal goblet and absorptive cells. As expected from their role in terminal glycosylation, the two glycosyltransferases and their products, sialic acid residues and blood group A substance, were localized in the trans cisternae of the Golgi apparatus of goblet cells. In contrast, however, they were found throughout the Golgi apparatus stack of adjacent absorptive cells, with the exception of the fenestrated first cis cisterna. The results are in contrast to the general view that enzymes in the glycosylation pathway are arranged in a cis to trans gradient across the Golgi apparatus and that such polarized distributions may instead be cell type-specific.

ABO Blood-Group System↗
PubMed1988

An intrinsic membrane glycoprotein of the golgi apparatus with O-linked N-acetylglucosamine facing the cytosol.

We have recently described the occurrence of integral membrane glycoproteins in rat liver smooth and rough endoplasmic reticulum with O-N-acetylglucosamine facing the cytosolic and luminal sides of the membrane (Abeijon, C., and Hirschberg, C. B. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 1010-1014). We now report that integral membrane glycoproteins with cytosolic facing O-N-acetylglucosamine also occur in membranes of rat liver Golgi apparatus. This was determined following incubation of vesicles from the Golgi apparatus, which were sealed and of the same membrane topographical orientation as in vivo, with UDP-[14C]galactose and saturating amounts of bovine milk galactosyltransferase. This enzyme does not enter the lumen of the vesicles and specifically catalyzes the addition of galactose, in a beta 1-4 linkage, to terminal N-acetylglucosamine. Under these conditions, galactose was transferred to a glycoprotein of molecular mass of 92 kDa. This protein was insoluble in sodium carbonate, pH 11.5, conditions under which integral membrane proteins remain membrane bound and was insensitive to treatment with peptide:N-glycosidase F. beta Elimination and chromatography showed that radiolabeled galactose was part of a disaccharide which was characterized as Gal beta 1-4GlcNAcitol. This glycoprotein is specific of the Golgi apparatus membrane. Intrinsic membrane glycoproteins with this unusual carbohydrate membrane orientation thus occur in the endoplasmic reticulum and Golgi apparatus of rat liver.

Acetylglucosamine↗
PubMed1988

Microtubules and Ca2+-sequestering membranes in the mitotic apparatus, isolated by a new method.

The mitotic apparatus of sea urchin embryos was isolated using a polyethylene glycol (PEG)/EGTA-medium. Such a procedure preserves the birefringence and the Ca2+ lability of the isolated mitotic apparatus. The method of isolation gives good preservation of the microtubules and of the intracellular Ca2+-transport system as visualized by a monoclonal antibody to a 46-kDa protein. Triple fluorescence studies allow a comparison of the relative locations of microtubules, Ca2+-sequestering membranes and chromatin (by Hoechst 33342) in the mitotic apparatus. We find that the Ca2+-sequestering membranes are concentrated mainly in the centers of the asters and do not follow the distribution of microtubules in the mitotic apparatus. Regulation of microtubules by Ca2+ may not depend on immediate contiguity of microtubules and the Ca2+-regulating sites.

Animals↗
PubMed1969

Characterization of lipoprotein particles isolated from the Golgi apparatus of rat liver.

It has been proposed that particles within tubules and vesicles of the Golgi apparatus of liver cells are precursors of very low density lipoproteins in blood plasma. To characterize these particles we isolated a cell fraction rich in Golgi apparatus and associated particles from rat liver in quantities sufficient for analysis. Particles freed from the membranes of the Golgi apparatus and floated at d = 1.006 were studied by chemical analysis, immunodiffusion, and paper electrophoresis. The lipid composition of the Golgi particles was similar to that of very low density lipoproteins from the same rats. The protein content was about 10% of dry weight for both the Golgi particles and plasma very low density lipoproteins. The Golgi particles formed lines of identity with plasma very low density lipoproteins during immunodiffusion against antiserum to plasma very low density lipoproteins. On paper electrophoresis, however, many Golgi particles remained near the origin, with only a few migrating to the pre-beta position. It was concluded that the lipoproteins in the Golgi apparatus are the precursors of plasma very low density lipoproteins.

Animals↗
PubMed1984

An electrogenic proton pump associated with the Golgi apparatus of mouse liver driven by NADH and ATP.

Golgi-apparatus membranes, isolated from mouse liver, pump protons inwards, when supplied with NADH or ATP. The acidification of Golgi-apparatus cisternae and vesicles was detected with neutral red, a permeant dye, as a difference in absorbance at 550 nm minus that at 600 nm. The maximum rates detected with NADH and ATP were between 0.0006-0.0009 and 0.0030-0.0050 delta OD units/mg of protein/min, respectively, at pH 7.5. The outside buffer used was a bovine serum albumin suspension. The acidification of Golgi apparatus was inhibited from 45 to 100% by ionophores and from 22 to 100% by uncouplers. The results implicate both ATP and a redox system coupled to NADH oxidation in the acidification of Golgi-apparatus membranes.

Adenosine Triphosphate↗
PubMed1984

Antibodies from patients with autoimmune disease react with a cytoplasmic antigen in the Golgi apparatus.

In this study we report the identification of an antibody in the sera of some patients with autoimmune disease that reacted with a cytoplasmic antigen localized within the Golgi apparatus. The antibody reacted with all tissues investigated, which included pancreas, kidney, testis, liver, thymus, and spleen. In addition, it reacted with some human peripheral circulating lymphocytes, murine peritoneal macrophages, and a variety of tissue culture cell lines, which included HEp-2 cells (human epithelial carcinoma), baby hamster kidney cells, a canine thymus cell line, a primary kidney cell line, Ehrlich ascites cells, Wil-2 cells, and Raji cells. The antigen is located in the same region stained by the histochemical reaction for thiamine pyrophosphatase, thus indicating that the antigen is located within the Golgi apparatus. The antigen was not demonstrated by immunodiffusion of saline extracts of rabbit thymus, pancreas, or liver. The antigen in HEp-2 cells was resistant to RNase A, DNase I, micrococcal nuclease, and to extraction with 0.1 N HC1, but was sensitive to trypsin and Proteinase K. Eight patients with anti-Golgi antibodies have been identified. Six of the eight had systemic lupus erythematosus. Autoantibodies to a Golgi apparatus antigen might serve as a useful biologic marker to study the functional relationship of the Golgi apparatus to lymphocytes and macrophages.

Adult↗
PubMed1983

Subfractionation of rat liver Golgi apparatus by free-flow electrophoresis.

Using the technique of preparative free-flow electrophoresis, cisternae of unstacked rat liver Golgi apparatus were separated into a series of fractions of increasing content of sialic acid, thiamine pyrophosphatase and 5'-nucleotidase, markers regarded as being concentrated toward the mature Golgi apparatus face. These same fractions showed a decreasing content of nucleoside diphosphatase, an endoplasmic reticulum marker. Fractions enriched in sialic acid also were enriched in cisternae from the mature or trans face of the Golgi apparatus as deduced from cytochemical criteria. Those fractions least enriched in sialic acid contained cisternae that accumulated deposits of reduced osmium under standard conditions, a test used to mark the opposite, forming or cis-face. Thus subfractionation along the functional polarity axis of the Golgi apparatus with separation of cis and trans face cisternae has been achieved.

Animals↗
PubMed1983

Kinetics of Golgi apparatus membrane flux following monensin treatment of embryogenic carrot cells.

Ultrastructural changes resulting from treatment with the sodium selective ionophore, monensin, were studied in embryogenic suspension cultures of carrot, Daucus carota (L.) in the presence of 10 microM monensin, an early change in the Golgi apparatus was an increase in the number of cisternae per stack (dictyosome). An average of one additional cisterna per stack was formed within the first 2 to 4 min of monensin treatment; in some experiments a second cisterna was formed within about 8 min. Thereafter, large vacuoles began to appear in the cytoplasm adjacent to the Golgi apparatus with a return of the number of cisternae per dictyosomal stack to the control number of about 5. Cells treated comparable but in the absence of monensin showed no ultrastructural changes during the entire observation period. By 1 h of monensin treatment, the regions of the cells containing dictyosomes were populated by large number of vacuoles (up to 20 or more per electron microscope section). These vacuoles were interpreted as swollen dictyosome cisternae that separated from the stack but had not migrated from the Golgi apparatus zone in the monensin-treated cells. The results permitted an estimation of the average time for formation of a new dictyosome cisterna of 2 to 4 min. This range of values agreed with estimates for mammalian cells from short time labeling and turnover experiments of 3 to 4 min assuming a dynamic model for Golgi apparatus function in which cisternae are released from a maturing face and new cisternae are built up at an opposite or forming face.

Furans↗
PubMed1981

Inhibition of Golgi apparatus-mediated secretion by cinnamic acid derivatives.

Two test systems have been utilized for screening potential inhibitors of Golgi apparatus function. In one system we measured formation of external polysaccharide droplets by the outer cap cells of maize roots. The droplets, direct products of the Golgi apparatus, were quantitated by visual estimates of droplet size compared to known standards. In the second system, we monitored secretory granule formation in the parotid gland of the rat, an activity also mediated by the Golgi apparatus. Parotid gland slices were stimulated with epinephrine to achieve 90% release of granules. The ability of the Golgi apparatus to package new secretory granules was then tested by incubating degranulated gland slices in the presence of putative inhibitors followed by restimulation with epinephrine. The amounts of alpha-amylase or (3H)leucine labeled proteins secreted into the medium were used as measures of secretory granule formation. The phenolic acid cinnamic acid and a related compound scopoletin were found to show substantial inhibition of secretion in both test systems.

Animals↗
PubMed1981

The juxtaglomerular apparatus: anatomical considerations in feedback control of glomerular filtration rate.

The juxtaglomerular apparatus is an anatomical unit located at the hilus of the glomerulus and is believed to be involved in feedback control of renal blood flow and glomerular filtration rate. In the mammal, it consists of the glomerular arterioles and extraglomerular mesangium (the vascular component) and the macula densa (the tubular component). Juxtaglomerular granular cells are modified smooth muscle cells and are believed to be the source of renin. They are present in the vascular component, being most numerous in the afferent arteriole. The macula densa segment of the distal tubule is characterized by closely packed nuclei, the basal or lateral position of the Golgi apparatus, and dispersed mitochondria that show little association with the reduced infoldings of the basal membrane. In addition to these morphological differences, there are marked histochemical differences between the macula densa and the adjacent segments of the distal tubule. Tubule-vessel contact appears to vary in extent and ultrastructure. The macula densa forms extensive and complex contact with the extraglomerular mesangial region. Contact with the arterioles may consist of simple apposition of basement membranes. Fluorescent histochemistry and electron microscopy demonstrate a consistent monoaminergic innervation of the juxtaglomerular apparatus. Autoradiography shows that axons associated with the juxtaglomerular apparatus are able to incorporate exogenous tritiated norepinephrine. Nerve endings are observed on cells of the vascular component and less frequently on the tubules of the juxtaglomerular region.

Animals↗
PubMed1976

The response of the juxtaglomerular apparatus to stimuli effecting renin or erythropoietin release in canine renal allografts.

The functioning canine renal allograft produces plasma renin activity (PRA) and erythropoietin (ESF) activity and can maintain normal blood pressure and normal erythropoiesis. Moreover, in response to various provocative stimuli it can: (i) increase plasma renin activity in response to low sodium intake; (ii) suppress PRA in response to high sodium intake; (iii) produce increased serum erythropoietin in response to hypoxia. The granulation activity of the juxtaglomerular apparatus correlates best with the degree of graft rejection and with the PRA in groups manipulated by changing sodium balance. This is not the case with hypoxia. Thus, the juxtaglomerular apparatus, even in the presence of vascular changes seen with the severe degree of rejection in renal allografts, can respond to stimuli that can regulate renin release. Renin production by the transplanted kidney can be dissociated from ESF secretion. Blood pressure changes in the present model were not directly associated with increased PRA or juxtaglomerular apparatus activity. In such conditions hypertension can exist in the presence of suppressed PRA and without hypergranulation of the apparatus. The majority of correlations of this study thus establish a close association of the degree of juxtaglomerular index activity with PRA levels, rather than ESF.

Animals↗
PubMed1996

Chlamydia trachomatis interrupts an exocytic pathway to acquire endogenously synthesized sphingomyelin in transit from the Golgi apparatus to the plasma membrane.

Chlamydia trachomatis acquires C6-NBD-sphingomyelin endogenously synthesized from C6-NBD-ceramide and transported to the vesicle (inclusion) in which they multiply. Here we explore the mechanisms of this unusual trafficking and further characterize the association of the chlamydial inclusion with the Golgi apparatus. Endocytosed chlamydiae are trafficked to the Golgi region and begin to acquire sphingolipids from the host within a few hours following infection. The transport of NBD-sphingolipid to the inclusion is energy- and temperature-dependent with the characteristics of an active, vesicle-mediated process. Photo-oxidation of C5-DMB-ceramide, in the presence of diaminobenzidine, identified DMB-lipids in vesicles in the process of fusing to the chlamydial inclusion membrane. C6-NBD-sphingomyelin incorporated into the plasma membrane is not trafficked to the inclusion to a significant degree, suggesting the pathway for sphingomyelin trafficking is direct from the Golgi apparatus to the chlamydial inclusion. Lectins and antibody probes for Golgi-specific glycoproteins demonstrate the close association of the chlamydial inclusion with the Golgi apparatus but do not detect these markers in the inclusion membrane. Collectively, the data are consistent with a model in which C.trachomatis inhabits a unique vesicle which interrupts an exocytic pathway to intercept host sphingolipids in transit from the Golgi apparatus to the plasma membrane.

4-Chloro-7-nitrobenzofurazan↗
PubMed1997

Influence of LEPK on biochemical activity and morphology in situ of liver Golgi apparatus from control and streptozotocin-diabetic rats.

This paper presents yields of Golgi-rich membrane isolation, the activity of galactosyltransferase (GalT), the marker enzyme of Golgi apparatus as well as the morphology of the organelle from the livers in situ, in two groups of rats. One group consisted of control rats injected twice intraperitoneally with LEPK. Second group consisted of rats injected with LEPK and additionally after 24hrs given streptozotocin (SZ) to induce experimental diabetes. The results were compared with our previous investigations in control and diabetic rats. In the latter the activity of GalT was diminished, therefore diminishing glycosylation ability, and destructing Golgi apparatus morphology. This experiment shows that two-fold injection of LEPK prior to SZ does not prevent from changes in such biochemical parameters as free blood glucose level, yield of liver Golgi membranes isolation or total activity of GalT. For the first time in c. 30% of investigated rats the inactive enzyme of Golgi apparatus was found in the rats treated with LEPK+SZ. Morphological investigations of liver Golgi apparatus in rats treated with LEPK show slightly increased secretory activity with similar to untreated control rats morphological structure of this organelle. In the rats treated with LEPK and SZ the same morphological changes as in diabetic liver were found, however, such dramatic alterations as in SZ-diabetic rats were never found, irrespective of active or inactive GalT.

Animals↗
PubMed1999

A simple multi-specimen apparatus for fixed stress fatigue testing.

To cope with the time-consuming characteristics of fatigue tests, a multi-specimen fatigue testing apparatus, which could test 10 specimens at a time, was designed, constructed, and tested. The specimens are fixed around a rotating axis, and the required stresses are applied by weights attached on the other end of each specimen. The test mode can be categorized as a stress-controlled flexural fatigue test. Its performance was tested by comparing it with a commercial three-point bending fatigue testing apparatus. The stress versus number of cycles to failure curves of poly(methylmethacrylate) (PMMA), which were obtained from both fatigue testing equipment, showed results that were similar to each other. The fatigue test results of acrylic bone cement in a fixed-stress mode also showed good agreement between the data obtained from the new apparatus and the commercial apparatus. The test results seem quite reliable and show feasibility of significantly reducing the overall test periods. It may be valuable, especially for the fatigue tests, which must be done with a low frequency and a low applied stress level such as a fatigue test of bone cements.

Bone Cements↗