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PubMed1985

Nonrandom positioning of Golgi apparatus in pancreatic B cells.

The Golgi apparatus has a polarized distribution in a variety of cell types, and in certain epithelia its intracellular position correlates with the direction of vectorial transport and release of secretory products. We have studied quantitatively the orientation of the Golgi apparatus in pancreatic islet B cells by examining its location with respect to the juxtacapillary face of the cell. This was done a) at the light microscope level on semithin sections of osmium-impregnated islets, and b) at the ultrastructural level on thin sections of intact pancreas. The data obtained with both methods show that in pancreatic B cells the Golgi apparatus is preferentially located in the position opposite to the juxtacapillary face of the cell. These results suggest a structural polarization of B cells, which may be important for the coordinate function of islets of Langerhans.

Animals↗
PubMed1991

Differential distribution of salivary agglutinin and amylase in the Golgi apparatus and secretory granules of human salivary gland acinar cells.

The secretory granules of salivary glands often display complex internal substructures, yet little is known of the molecular organization of their contents or the mechanisms involved in packaging of the secretory proteins. We used post-embedding immunogold labeling with antibodies to two secretory proteins, agglutinin and alpha-amylase, to determine their distribution in the Golgi apparatus and secretory granules of the human submandibular gland acinar cells. With monoclonal antibodies specific for carbohydrate epitopes of the agglutinin, reactivity was found in the trans Golgi saccules, trans Golgi network, and immature and mature secretory granules. In the granules, labeling was seen in regions of low and medium electron density, but not in the dense cores. Reactivity seen on the apical and basolateral membranes of acinar and duct cells was attributed to a shared epitope on a membrane glycoprotein. Labeling with a polyclonal antibody to amylase was found in the Golgi saccules, immature and mature secretory granules, but not in the trans Golgi network. In the granules, amylase was present in the dense cores and in areas of medium density, but not in the regions of low density. These results indicate that these two proteins are distributed differently within the secretory granules, and suggest that they follow separate pathways between the Golgi apparatus and forming secretory granules. Small vesicles and tubular structures that labeled only with the antibodies to the agglutinin were observed on both faces of the Golgi apparatus and in the vicinity of the cell membrane. These structures may represent constitutive secretion vesicles involved in transport of the putative membrane glycoprotein to the cell membrane.

Agglutinins↗
PubMed1993

Modulation of the Golgi apparatus in stimulated and nonstimulated prolactin cells of female rats.

The three-dimensional structure of the Golgi apparatus and its compartments in prolactin cells has been examined in lactating rats in which secretion of prolactin was suppressed by removing the litter or stimulated by allowing the pups to suckle again. As soon as 2 hr after removal of the litter, large irregular progranules and numerous large pale vesicles accumulated in the trans-Golgi area together with vesicular or tubular fragments. The cis-tubular network was no longer recognizable on the cis-face of the Golgi ribbon; the saccules of the midcompartment were partitioned by narrow fissures and also became perforated in register by numerous fenestrations of various sizes and irregular contours. The concomitant appearance of numerous vesicles in the cavities thus formed as well as in the surrounding cytoplasm indicated that they probably arose by the progressive cavitation and fragmentation of saccules of the mid compartment. Such a process, which reached a maximum between 4 and 6 hr after removal of the litter from the mother, was no longer observed at 8 and 12 hr, at which time intervals the Golgi apparatus was reduced in size with no cis-tubular elements and progranules on its trans-aspect and few vesicles in its surroundings. When mothers, separated from their litters for a period of 12 hr, were returned to their pups for 20 min, the cis-tubular network reappeared on the cis-aspect of the Golgi stacks and presumably formed by fusion of vesicles and anastomosed tubules located next to the cisternae of the rough endoplasmic reticulum. In addition, the structure of the midsaccules returned to the stimulated condition, and early progranules were again segregated within the trans-most saccules of the Golgi stack. Hence, the Golgi apparatus of prolactin cells was rapidly and deeply modified in the presence or absence of stimulation.

Animals↗
PubMed1994

Phosphoprotein phosphatase 1 (PP1) is a component of the isolated sea urchin mitotic apparatus.

A protein component of isolated mitotic apparatus having a relative molecular mass of 62,000 (p62) is a substrate of a calcium/calmodulin dependent protein kinase, and the phosphorylation of p62 in vitro correlates directly with microtubule disassembly. In vivo experiments have determined the phosphorylation of p62 increases after fertilization; maximum incorporation of phosphate occurs during late metaphase/early anaphase and decreases thereafter. Because the level of p62 is constant throughout the cell cycle [Johnston and Sloboda, 1992: J. Cell Biol. 119:843-54] the decrease in phosphorylation of p62 observed after anaphase onset is most likely due to the action of a phosphatase. By examination of the relative amount of phosphorylated p62 which remained radiolabeled as a function of time using a standard in vitro phosphorylation assay, the activity of a phosphoprotein phosphatase capable of dephosphorylating p62 in the isolated mitotic apparatus was observed. To characterize the p62 phosphatase, okadaic acid and calyculin A were used to inhibit the dephosphorylation of p62 in vitro. It was found that specific concentrations of okadaic acid (50-500 nM) and of calyculin A (10-100 nM) were effective at inhibiting the dephosphorylation of p62 in vitro. Lower concentrations of either inhibitor had a negligible effect on dephosphorylation of p62. These data indicate the presence of phosphoprotein phosphatase type 1 activity associated with mitotic apparatus isolated from sea urchin embryos using the procedures described here. The implications of these findings relative to our understanding of the regulation of mitosis and cytokinesis are discussed.

Animals↗
PubMed1989

Functional compartments of the yeast Golgi apparatus are defined by the sec7 mutation.

The role of the SEC7 gene product in yeast intercompartmental protein transport was examined. A spectrum of N-linked oligosaccharide structures, ranging from core to nearly complete outer chain carbohydrate, was observed on glycoproteins accumulated in secretion-defective sec7 mutant cells. Terminal alpha 1-3-linked outer chain mannose residues failed to be added to N-linked glycoproteins in sec7 cells at the restrictive temperature. These results suggest that outer chain glycosyl modifications do not occur within a single compartment. Additional evidence consistent with subdivision of the yeast Golgi apparatus came from a cell-free glycoprotein transport reaction in which wild-type membranes sustained outer chain carbohydrate growth up to, but not including, addition of alpha 1-3 mannose residues. Golgi apparatus compartments may specialize in addition of distinct outer chain determinants. The SEC7 gene product was suggested to regulate protein transport between and from functional compartments of the yeast Golgi apparatus.

Biological Transport↗
PubMed2003

Shape and position of the sarcoplasmic reticulum and the Golgi apparatus in the sole plate and remaining subsarcolemmal muscle region of the mouse using imidazole-osmium staining.

By means of thin (< or =150 nm) and thick (>150 nm) sections, the shape and position of the sarcoplasmic reticulum and of the Golgi apparatus in the sole plate and in the remaining subsarcolemmal sarcoplasmic region were investigated. For this purpose the membranes were stained by means of imidazole-osmium postfixation and unstained sections analyzed under the electron microscope. Both in the sarcoplasma of the sole plate and around the muscle fiber nuclei, a network of tubules is visible after imidazole-osmium staining which can be identified as the sarcoplasmic reticulum solely on the basis of its contacts with the perinuclear cistern and the cisterns of the triads. Findings in literature on the position of the Golgi apparatus are confirmed and similar spatial relationships and vesiculations between the perinuclear cisterns and the Golgi apparatus of the sole plate nuclei and the other subsarcolemmal fiber nuclei are also demonstrated using this new staining method.

Animals↗
PubMed2005

Alligator tears: a reevaluation of the lacrimal apparatus of the crocodilians.

The Harderian gland is a poorly understood anterior ocular gland that occurs in most terrestrial vertebrates. Numerous extraorbital functions have been ascribed to the Harderian gland, principally based on its association with the nasolacrimal duct. Few studies have centered on archosaurs and the majority of those available focused solely on the Harderian gland of birds. Little is known about the lacrimal apparatus of the crocodilians. We examined the lacrimal apparatus of several specimens of Alligator mississippiensis anatomically, histologically, and histochemically and studied the embryogenesis of this system. The nasolacrimal duct possesses a distal secretory area, which is more convoluted than that of typical mammals or lepidosaurs. The alligator Harderian gland possesses a unique combination of characteristics found in lepidosaurs, birds, and mammals. Like that of both mammals and lepidosaurs, it is a large, tuboloacinar gland that appears to secrete both mucoprotein and lipids. However, the presence of blood vessels and immune cells is reminiscent of that of the avian Harderian gland. The immunogenesis of the alligator Harderian gland appears to be tied to the development of the vascular system. The presence of a distinct palpebral gland in the anterior aspect of the ventral eyelid is a feature unique to alligators. Based on position, this gland does not appear to be homologous to the anterior lacrimal gland of lepidosaurs. Lymphatic aggregations were also found in the palpebral gland. The presence of interstitial immune cells in the orbital glands of alligators suggests that the alligator lacrimal apparatus, like that of birds, may play a role in the head-associated lymphatic tissue system.

Alligators and Crocodiles↗
PubMed1982

Histological and ultrastructural studies of the human juxtaglomerular apparatus in Bartter's syndrome and renal artery stenosis.

Histological and ultrastructural studies of the juxtaglomerular apparatus (JGA) were performed on renal biopsy material from three cases of Bartter's syndrome and two cases of renal artery stenosis. These cases of known JGA hyperfunction were compared with the apparatus in a presumed inactive or basal state as in minimal lesion glomerulonephritis. Light microscopic assessment of the ease of JGA identification, its size and cellularity, provides a valuable reflection of activity and indicates those cases which require ultrastructural assessment of granule turnover. Granule stains often failed to demonstrate any significant increase in granule number in the two conditions studied, and only ultrastructural studies allowed evaluation of secretory activity, rhomboid granule formation and granule release. From these investigations, a proposed mechanism of granule turnover is suggested. The morphological findings in both Bartter's syndrome and renal artery stenosis support the concept of hyperfunction of the apparatus. They may help to elucidate the pathogenesis of Bartter's syndrome and to predict the outcome of surgical intervention in renal artery stenosis. Such studies could profitably be performed on renal biopsies in other disease states, so augmenting our understanding of the contribution of the JGA to the pathogenesis of a variety of glomerular and vascular lesions.

Bartter Syndrome↗
PubMed1983

Histological and ultrastructural studies of the human juxtaglomerular apparatus in benign and malignant hypertension.

The light and electron microscopic appearances of the human juxtaglomerular apparatus in benign essential and malignant (accelerated phase) hypertension are described. In the former, the variability of appearances precludes assessment of the importance of the apparatus in the pathogenesis or progression of the disease. The hyperplastic appearance of the apparatus in malignant hypertension supports the concept of renin hypersecretion in this phase. Mechanisms of JGA stimulation are considered and the possibility of a new source of renin discussed. It is suggested that morphological appraisal of cellular activity could be correlated with chemical estimations, allowing a clearer delineation of the role of the renin-angiotensin system in the pathogenesis and progression of benign and malignant hypertension. This might be of value in assessing the cellular response to various specific pharmacological agents used in the management of these conditions.

Adult↗
PubMed2000

Nonylphenol provokes a vesiculation of the Golgi apparatus in three fish epidermis cultures.

The aim of this work was to study the effects of nonylphenol and waste water on the cell ultrastructure of fish skin. Therefore, besides a recently established primary cell culture and a cell line, an epidermal tissue culture of fish was developed and tested. In all three systems a prominent vesiculation of the Golgi apparatus was observed after exposure to nonylphenol, which has not been described before and therefore strongly suggests an effect that might indicate exposure to nonylphenol and/or related substances. The Epithelial papulosum cyprini cell line was the most sensitive to nonylphenol, followed by the primary cell culture of epidermis cells and then the explant tissue culture. The vesiculation of the Golgi apparatus was accompanied by degenerative changes in the two cell cultures only. The lack of degenerative changes in the cells of the tissue culture was discussed with respect to the presence of differentiated cells that might better be able to protect themselves by mucous or by an activated xenobiotic metabolism. In a second type experiment, a waste water sample containing small concentrations of nonylphenol was applied to the cultures. It did not lead to a vesiculation of the Golgi apparatus, probably because the nonylphenol concentrations in the waste water were too low to induce the vesiculation. The cultures exposed to waste water revealed unspecific degenerative cellular changes. Additionally, explant cultures were prepared from fish that had survived a 6-month exposure to polluted river water. In these cultures a higher number of mitochondria containing myelin bodies were observed when compared to control cultures. Consequently, exposure to polluted water containing a mixture of substances in vitro and in vivo was found to lead to degenerative alterations in the ultrastructure of the cells.

Animals↗
PubMed1985

Dictyosome-like structures from guinea-pig testes lack galactosyltransferase, a Golgi apparatus marker.

More than twenty different enzyme activities of fractions containing dictyosome-like structures (DLS) as a dominant cell component were monitored. Plasma membrane vesicles were a major contaminant of the DLS fractions, which, presumably as a consequence, were enriched somewhat in plasma membrane markers. The lysosomal enzymes arylsulfatase and latent acid phosphatase were present in the DLS fractions as were the Golgi apparatus activities thiamine pyrophosphatase and nucleoside diphosphatase. The presence of the latter two enzymes in DLS, plus NADH-ferricyanide reductase, has been verified from cytochemistry. On the other hand, the Golgi apparatus marker, galactosyltransferase, was not enriched in DLS fractions and appeared to be absent. This latter finding, verified from cytochemistry with isolated DLS fractions and, in situ, from [3H]galactose incorporation by testis tubules with analysis by autoradiography, provides the first clear biochemical characteristic that serves unequivocally to distinguish DLS from conventional Golgi apparatus.

Animals↗
PubMed1990

Regional variations in nerve cell responses to trimethyltin intoxication in Mongolian gerbils and rats; further evidence for involvement of the Golgi apparatus.

The different responses of neurons with distinctive variations in morphology and function, confirm earlier observations of the lack of uniformity in the reaction of nerve cells to trimethyltin. Thus, hippocampal pyramidal and cortical neurons in both rat and Mongolian gerbil (M. unguiculatus) show abundant lysosomal dense bodies and disorganisation of the protein-synthesising apparatus. Cerebellar Purkinje cells in gerbil, but not in rat, show striking increases in smooth membrane systems, while dense bodies are insignificant in both species; large motor-type neurons in brain stem and spinal cord in both species do not accumulate dense bodies, but their rough endoplasmic reticulum (RER) may undergo intense vacuolation with or without subsequent cell death; and by contrast, spinal ganglion cells of both species may form an excess of dense bodies and, in the gerbil, vacuolation of RER. In contrast with these varied responses to trimethyltin most neurons, large and small, in both species regularly undergo striking vacuolation of the Golgi apparatus in the earliest phase of the intoxication, a constant feature that probably reflects the site of the primary cytotoxic lesion; all other changes we consider are secondary to such damage to the Golgi apparatus, however this may come about. These observations are discussed in relation to earlier reports of the variable effects of trimethyltin and with the metabolic changes reported in trimethyltin intoxication that in general accord with these morphological conclusions.

Animals↗
PubMed1985

Cytochemical studies of acid phosphatases in the rat lateral prostate with special reference to secretory apparatus and lysosome system.

A cytochemical study of acid phosphatase (AcP-ase) in the lateral prostate of the rat was performed to investigate whether AcP-ase in the secretory apparatus can be distinguished from AcP-ase in lysosomes and their related structures. Two types of AcP-ase were observed in the rat lateral prostate. One was found in the secretory apparatus (Golgi saccules and some Golgi vesicles, condensing and secretory vacuoles), and reacted well with naphthol AS-BI phosphate (N AS-BI P) as substrate; the other was found in the lysosomes and Golgi-associated endoplasmic-reticulum-lysosome system (GERL)-like structure, and reacted well with beta-glycerophosphate (beta GP) as substrate. Although the AcP-ase which reacted well with N AS-BI P was also observed in certain portions of pleomorphic lysosomes, it was concluded that it was the same as the AcP-ase found in the condensing and secretory vacuoles, since a lysosome engulfing a condensing vacuole was often observed. Therefore, it is concluded that the AcP-ase in the secretory apparatus in the rat lateral prostate is different from the AcP-ase in lysosomes. Condensing vacuoles appear to originate from particular portions of Golgi saccules, but not from the GERL or GERL-like structure, at least in the rat lateral prostate.

Acid Phosphatase↗
PubMed1983

Nerve growth factor induced changes in the Golgi apparatus of PC-12 rat pheochromocytoma cells as studied by ligand endocytosis, cytochemical and morphometric methods.

Cells of the PC-12 rat pheochromocytoma cell line respond to nerve growth factor (NGF) by sprouting neurites and biochemically differentiating into sympathetic ganglion-like cells. NGF-stimulated ('differentiated') and unstimulated ('undifferentiated') cells were studied by cytochemical techniques for the localization of the enzymes acid phosphatase (ACPase) and thiamine pyrophosphatase (TPPase), and by a morphometric analysis of the distribution of endocytosed wheat-germ agglutinin labelled with horseradish peroxidase (WGA-HRP). Both cytochemical stains showed the enzymes to be distributed in lysosomes and certain cisternae of the Golgi apparatus in both NGF stimulated and unstimulated cells. ACPase was not confined to GERL (Golgi-endoplasmic reticulum-lysosome) as in certain other cells. The morphometric studies demonstrated that the reaction product of the internalized WGA-HRP occupied 4.7% of the cytoplasmic area in unstimulated cells and 4.5% in NGF-stimulated ones. Despite this similarity, the distribution of the WGA-HRP among the studied intracellular compartments in these two cell groups varied. In the NGF-stimulated cells 3.3% of the WGA-HRP reaction product was found in the innermost Golgi cisterna(e) while in unstimulated cells only 0.3% was seen in this compartment. Similarly, 4.3% of the WGA-HRP stain was found in small vesicles at the 'trans' aspect of the Golgi apparatus in stimulated cells, when only 0.3% of the stain occupied this compartment in 'undifferentiated' cells. The morphometric analysis also revealed that when the PC-12 cells were stimulated with NGF, the Golgi apparatus increased in area by approximately 70%. These findings are consistent with the hypothesis that NGF induced differentiation of PC-12 cells is coupled with enhanced endocytosis of WGA and probably of its 'receptor' to the innermost Golgi cisterna(e) and the closely associated vesicles.

Acid Phosphatase↗
PubMed1976

Histochemical studies on the morphology of the Golgi apparatus and on the enzymes of carbohydrate metabolism in various nuclei of the rat mesencephalon.

Detailed histochemical studies have been conducted on the distribution of various enzymes such as thiamine pyrophosphatase, alpha-glucan phosphorylase, hexokinase, glucose-6-phosphate dehydrogenase, aldolase, lactate dehydrogenase and succinate dehydrogenase in various components of the nucleus Edinger-Westphali, nucleus n. oculomotorii, nucleus ruber and nucleus niger of healthy adult male Wistar strain rats. The thiamine pyrophosphatase reaction showed the morphological patterns of the Golgi apparatus characteristic for each nucleus. The Golgi apparatus was well developed in the nucleus Edinger-Westphali, composing a network of highly fenestrated plates in the nucleus n. oculomotorii and nucleus ruber, and a simple network in the nucleus niger. These results indicate that the former three nuclei need a rich energy supply and argue against the possibility that the four nuclei have a secretory role. The neurons of the nucleus Edinger-Westphali may derive their energy mainly from glucose of the circulating blood, but glial cells may serve as energy donators to the neurons in the pars compacta of the nucleus niger, and the neurons of the other nuclei may derive energy from both sources. These conclusions are consistent with the morphological patterns of the Golgi apparatus.

Carbohydrate Metabolism↗
PubMed2002

Golgi apparatus and TGN during endocytosis.

Wheat germ agglutinin labelled with horseradish peroxidase (WGA) was used for analyses of endosomal compartments and Golgi apparatus in HepG(2) hepatoma cells during early and late periods of endocytosis. WGA was rapidly transferred into the Golgi region. Transport of internalised WGA into the Golgi apparatus could be classified in three stages. A short stage I, characterised by predominance of vesicular endosomes, was followed by stage II showing new formations of extended endocytic trans Golgi networks (TGNs); the endocytic TGNs comprised reticular and globular parts, showed intimate associations with segments of the endoplasmic reticulum and budding of multiple coated vesicles. Parts of the endocytic TGNs associated with trans Golgi cisternae and became integrated into Golgi stacks. During stage III, concomitantly with integration into the stacks, the endocytic TGNs decreased in size and stacked Golgi cisternae became prominent endocytic compartments. Our results show that endocytosis of WGA is connected with extensive membrane dynamics at the trans Golgi side: an endocytic TGN is newly formed, increases in size and is consumed again. The findings suggest that incorporation of TGN elements into Golgi stacks provides a mechanism for uptake of internalised WGA into the Golgi apparatus.

Endocytosis↗
PubMed2003

PMR1/SPCA Ca2+ pumps and the role of the Golgi apparatus as a Ca2+ store.

Besides the well-known sarco/endoplasmic-reticulum Ca(2+)-transport ATPases (SERCA), animal cells contain a much less characterized P-type Ca(2+)-transport ATPase: the PMR1/SPCA Ca(2+)/Mn(2+)-transport ATPase. SPCA is mainly targeted to the Golgi apparatus. Phylogenetic analysis indicates that it might be more closely related to a putative ancestral Ca(2+) pump than SERCA. SPCA supplies the Golgi apparatus, and possibly other more distal compartments of the secretory pathway, with the Ca(2+) and Mn(2+) necessary for the production and processing of secretory proteins. In the lactating mammary gland, SPCA appears to be the primary pump responsible for supplementing the milk with high (60-100 mM) Ca(2+). It could also play a role in detoxification of cells overloaded with Mn(2+). Mutations in the human gene encoding the SPCA pump ( ATP2C1) result in Hailey-Hailey disease, a keratinocyte disorder characterized by incomplete cell adhesion. Recent observations show that the Golgi apparatus can function as a Ca(2+) store, which can be involved in setting up cytosolic Ca(2+) oscillations.

ATP-Binding Cassette Transporters↗
PubMed2005

Localization of actin filaments on mitotic apparatus in tobacco BY-2 cells.

Actin filaments are among the major components of the cytoskeleton, and participate in various cellular dynamic processes. However, conflicting results had been obtained on the localization of actin filaments on the mitotic apparatus and their participation in the process of chromosome segregation. We demonstrated by using rhodamine-phalloidin staining, the localization of actin filaments on the mitotic spindles of tobacco BY-2 cells when the cells were treated with cytochalasin D. At prophase, several clear spots were observed at or near the kinetochores of the chromosomes. At anaphase, the actin filaments that appeared to be pulling chromosomes toward the division poles were demonstrated. However, as there was a slight possibility that these results might have been the artifacts of cytochalasin D treatment or the phalloidin staining, we analyzed the localization of actin filaments at the mitotic apparatus immunologically. We cloned a novel BY-2 alpha-type actin cDNA and prepared a BY-2 actin antibody. The fluorescence of the anti-BY-2 actin antibody was clearly observed at the mitotic apparatus in both non-treated and cytochalasin D-treated BY-2 cells during mitosis. The facts that similar results were obtained in both actin staining with rhodamine-phalloidin and immunostaining with actin antibody strongly indicate the participation of actin in the organization of the spindle body or in the process of chromosome segregation. Furthermore, both filamentous actin and spindle bodies disappeared in the cells treated with propyzamide, which depolymerizes microtubules, supporting the notion that actin filaments are associated with microtubules organizing the spindle body.

Actin Cytoskeleton↗