Search results for "Lysosome"
showing 10 items of 125 documents
Characterization of Endocytic Components of Liver Nonparenchymal Cells
1993
Liver is made up of at least five important cell types: hepatocytes, endothelial cells, Kupffer cells, pit cells, and fat-storing cells. These cells have been broadly classified into two groups: parenchymal cells, or the hepatocytes which comprise almost 65% of the liver cells (Miyai, 1979), and nonparenchymal cells, to which all the other cell types belong.
Acidic cytosolic proteins are preferentially imported into rat liver lysosomes.
1998
Previous studies have reported that lysosomes isolated from human diploid fibroblasts and from rat liver can selectively import and degrade specific proteins. We have now reinvestigated this selectivity using an in vitro assay with rat liver lysosomes and an extract of cytosolic proteins prepared from cultured cells labeled to equilibriums with [35S-]methionine. Analysis by two-dimensional gel electrophoresis and autoradiography of the cytosolic proteins bound to the lysosomal membrane and imported into the lysosomes shows that when all cytosolic proteins are simultaneously present in the in vitro assay the lysosomal uptake also occurs in a specific manner. These findings suggest that isola…
Vinblastine-induced autophagocytosis in cultured fibroblasts
1991
1. Balb/c 3T3 fibroblasts were incubated in a medium containing 10(-5) M vinblastine for 1, 2 and 3 hr. Morphometric analyses were performed after an incubation period of 2 hr. 2. The volume fraction of advanced autophagic vacuoles increased tenfold (P less than 0.05) concomitantly with a sixfold decrease in round lysosomes (P less than 0.01). 3. The volume fractions of pleomorphic lysosomes, nascent autophagic vacuoles and residual bodies did not differ significantly from the control values. 4. In many cells, advanced autophagic vacuoles resembled multivesicular bodies, which may indicate that the type of autophagocytosis occurring in cultured fibroblasts is microautophagy.
Neuraminidase deficiency presenting as non-immune hydrops fetalis
1984
A newborn infant with oedema, ascites and hepatosplenomegaly is described. In ascites fluid foamy macrophages were found, in a liver biopsy cytoplasmic inclusions and membrane-bound vacuoles were seen. Furthermore the child excreted excessive amounts of sialic acid-rich oligosaccharides in the urine, and therefore a neurovisceral degenerative disorder was assumed. The diagnosis of sialidosis was confirmed by enzymatic assay in cultured fibroblasts, in which a complete deficiency of the lysosomal enzyme neuraminidase could be demonstrated. After recurrent septicaemias the child became dystrophic and died at the age of 6 months. Our case is compared with sialidosis observed by other authors, …
Ultrastructural changes of the oenocytes of Gryllus bimaculatus DEG (Saltatoria, Insecta) during the moulting cycle
1974
1. The oenocytes of Gryllus bimaculatus are characterized by an abundant smooth-surfaced ER (ATER). In spite of the great cell size the plasma membrane never shows extensive infoldings during the moulting cycle. In addition to mitochondria there are very large numbers of microbodies containing peroxidase but apparently not uricase. Within the second part of the instar the microbodies lie along the clefts which run through the whole cell. 2. The following changes are observed in the course of a moulting cycle: Immediately after hatching the ATER is scarcely developed, some liposomes are located within areas of ATER disappearing some hours later. 20 hours after emergence glycogen deposits app…
Quantitative electron microscopic observations on Paneth cells of germfree and ex-germfree Wistar rats.
1986
Ultrastructural changes of Paneth cells of germfree (Gf) rats which had been inoculated with bacteria-containing feces from conventionally-reared (SPF) rats were quantitatively examined. 12 and 24 h after inoculation, the Paneth cells showed a striking decrease in the number of secretory granules and the occurrence of large vacuoles. Phagosomes containing bacteria were not seen. After 4 days, the secretory granules reaccumulated and smooth-surfaced apical vesicles increased in number. It is discussed that the large vacuoles may be related to membrane-retrieval events following the massive extrusion of secretory granules whereas the apical vesicles appear to serve this function when exocytos…
γ2-Adaptin is functioning in the late endosomal sorting pathway and interacts with ESCRT-I and -III subunits.
2010
Abstractγ2-Adaptin is a clathrin adaptor-related protein with unclear physiological function. Previous studies indicated that γ2-adaptin might act within the multivesicular body (MVB) protein-sorting pathway that is central to receptor down-regulation, lysosome biogenesis, and budding of enveloped viruses. Here, we have analyzed the effects of excess and deficit γ2-adaptin on exogenous and endogenous MVB cargoes and on the MVB machinery itself. Foreign cargoes, like retroviral Gags, are entrapped by overexpressed γ2-adaptin in detergent-insoluble polymers and blocked in budding. When viral budding involves MVB/endosomal structures, excess γ2-adaptin acts by accelerating lysosomal Gag destru…
Effect of freezing/thawing process in different sizes of blue fish in the Mediterranean through lysosomal enzymatic tests
2014
The assessment of freshness of different sizes of blue fish (Engraulis encrasicolus 12 cm, Sardina pilchardus 15 cm, Trachurus trachurus 40 cm, Scomber japonicus colias 60 cm) was carried out using non-conventional enzymatic methods. The activities of the three lysosomal enzymes (α-glucosidase (AG), β-galactosidase (B-GAL) and β-N-acetylglucosamidase (B-NA)) in extracts of blue fish muscle were measured over a period of 21 days of storage. A significant increase (p < 0.05) of AG activity was observed in all species, with a large increase seen after only one day of storage. B-NA activity increased slightly in sardines, horse mackerels and chub mackerel during frozen/thawed storage. Finally, …
RAB3GAP1 and RAB3GAP2 modulate basal and rapamycin-induced autophagy
2014
Macroautophagy is a degradative pathway that sequesters and transports cytosolic cargo in autophagosomes to lysosomes, and its deterioration affects intracellular proteostasis. Membrane dynamics accompanying autophagy are mostly elusive and depend on trafficking processes. RAB GTPase activating proteins (RABGAPs) are important factors for the coordination of cellular vesicle transport systems, and several TBC (TRE2-BUB2-CDC16) domain-containing RABGAPs are associated with autophagy. Employing C. elegans and human primary fibroblasts, we show that RAB3GAP1 and RAB3GAP2, which are components of the TBC domain-free RAB3GAP complex, influence protein aggregation and affect autophagy at basal an…
Tissue- and cell-specific expression of metallothionein genes in cadmium- and copper-exposed mussels analyzed by in situ hybridization and RT–PCR
2007
Abstract Metallothioneins (MTs) are metal-inducible proteins that can be used as biomarkers of metal exposure. In mussels two families of MT isoforms (MT10 and MT20) have been characterized. In this study, mussels (Mytilus galloprovincialis) were exposed to 200 ppb Cd and 40 ppb Cu for 2 and 9 days to characterize the tissue and isoform specificity of metal-induced MT expression. Non-radioactive in situ hybridization demonstrated that both MT isoforms were mainly transcribed in digestive tubule epithelial cells, especially in basophilic cells. Weaker MT expression was detected in non-ciliated duct cells, stomach and gill epithelial cells, haemocytes, adipogranular cells, spermatic follicles…