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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The time dependence of agglutination and cell-cell contact spreading in human erythrocytes exposed to wheat germ agglutinin (WGA) was characterized by light and electron microscopy. Cells (3 x 10(7)/mL) had a threshold lectin concentration in the range of 0.6-2.0 micrograms/mL for initial cell contact. Spreading was essentially completed within 60 and 2 min in undisturbed and gently agitated suspensions, respectively. The cells in large WGA agglutinates retained features of their initial disk form in contrast to the convex outlines of polycation or polyethylene glycol-induced agglutinates. Spreading of contact area was accompanied by development of a pattern of discrete contact regions separated by a distance of the order of 1 micron. Freeze fracture electron microscopy and studies with ferritin-labeled WGA showed no significant aggregation of intramembrane particles or specific lectin receptors under conditions when contact spreading occurred. It is argued that flow stress effects on cells in suspended agglutinates give rise to a situation where opposite membranes, at the leading edge of cell contact, are separated by a thin aqueous layer. When this intercellular water layer exceeds a critical length, it becomes unstable. The layer breaks up by surface wave development to form an array of intracellular water spaces. Formation of the aqueous spaces causes opposite membrane regions to move synchronously toward each other. Lectin molecules crosslink the wave crests to give spatially periodic contact points.
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PMID:Spreading of wheat germ agglutinin-induced erythrocyte contact by formation of spatially discrete contacts. 169 48

A survey of lectin-binding specificities present on rodent and human mesothelial cells propagated and maintained in tissue culture was made using fluorescein isothiocynate conjugated (FITC) lectins. Rodent and human cells exhibited cell-associated fluorescence following exposure to the FITC-lectins from C. ensiformis, T. vulgaris, A. hypogaea, E. cristagalli and B. simplicifolia, but not with lectins from G. max and D. biflorus. Rodent cells were also positive for FITC-M. pomifera lectin binding. Human, but not rodent, cells were positive for FITC-T. purpureas lectin binding. Exposure of rabbit mesothelial cells in vitro to FITC-lectins that bound to the cell surface resulted in the appearance of discrete loci of putatively intracellular fluorescence. Exposure of cells to ferritin-labelled T. vulgaris lectin at 37 degrees C for as little as 7.5 minutes resulted in the appearance of ferritin-size particles in intracellular vesicles. These results demonstrate 1. the presence of lectin-binding sites in and on peritoneal mesothelial cells from rodents and humans and 2. a possible role of such sites in mediating the entry of lectin-like endogenous molecules into the vacuolar apparatus of these cells.
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PMID:Lectin staining of peritoneal mesothelial cells in vitro. 172 46

Carbohydrates were studied on the surface of uterine epithelial cells by lectin-avidin-ferritin histochemistry. The lectins, wheat germ agglutinin, fucose binding protein, soy bean agglutinin and the lectin from Phytolacca americana were used in the study. Statistically significant increases in three carbohydrates on day 6 of pregnancy--the day of blastocyst implantation--were found when compared with oestrus. These increases could contribute to the mechanism of blastocyst attachment to uterine epithelium.
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PMID:Glycocalyx carbohydrates of uterine epithelial cells increase during early pregnancy in the rat. 176 85

The terminal carbohydrate residues of HIV I and II were detected by ferritin labeled lectins in electron microscopy. Different cell lines, which were infected with HIV I and II, expressed different terminal carbohydrate residues, which could also be detected on the viral envelope by electronmicroscopy. Especially N-Acetylgalactosamine residues were detected by Vicia villosa agglutinin only on Jurkat cells. This may have functional implications, since this lectin recognizes contrasuppressor T cells.
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PMID:Carbohydrate components of human immunodeficiency viruses type I and II. 209 Oct 51

By using colloidal iron and polycationic ferritin at low pH (1.8 and 1.9, respectively) as electron histochemical stains, we localized sialic acid moieties in the trabecular meshwork of normal human eyes. The markers were distributed continuously over the entire surface of the trabecular cells, but were localized linearly as well as randomly in the basal lamina. Within the beams, the markers were located irregularly in the collagen core, but were absent from the elastic tissue and from the 100 nm banded structures in the cortical zone. Pretreatment of the tissue with neuraminidase abolished this staining which indicates that sialated moieties are present in the stained structures. Biochemical analysis with the lectin Limax flavus agglutinin revealed that the major sialated polypeptides in individual samples of human trabecular meshwork migrated at apparent molecular weights of 56, 75, 95, 128, 140, 180 and 220 kDa under reducing conditions. The fractions at approximate molecular weights of 180 and 220 kDa include the sialoglycoproteins thrombospondin and fibronectin, respectively. The total content of sialic acid in the human trabecular meshwork (patient age range, 27-57 yr) was 3.6 +/- 0.6 mumol g-1 wet weight, as determined by a colorimetric assay. We conclude that significant quantities of sialic acid are present in the normal human trabecular meshwork as neuraminidase-sensitive alpha-ketosidically linked terminal residues of the polypeptides.
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PMID:Qualitative and quantitative analyses of sialic acid in the human trabecular meshwork. 224 33

Taste buds in the European catfish Silurus glanis were examined with electron microscopic lectin histochemistry. For detection of carbohydrate residues in sensory cells and adjacent epithelial cells, gold-, ferritin- and biotin-labeled lectins were used. A post-embedding procedure carried out on tissue sections embedded in LR-White was applied to differentiate between the sensory cells: The lectins from Helix pomatia (HPA) and Triticum vulgare (WGA) bound to N-acetyl-galactosamine and to N-acetylglucosamine residues occurring especially in vesicles of dark sensory cells. This indicates a secretory function of these cells. Most light sensory cells--with some exceptions, probably immature cells--, are HPA-negative. The mucus of the receptor field and at the top of the adjacent epithelial cells was strongly HPA-positive. Pre-embedding studies were performed in order to obtain information about the reaction of the mucus with lectins under supravital conditions. The mucus of the taste bud receptor field exhibited intensive binding to WGA, but not to the other lectins tested. Most lectins bound predominantly to the surface mucus of the nonsensory epithelium and to the marginal cells close to the receptor field. The strong lectin binding to mucins and the relatively weak lectin binding to cell surface membranes in pre-embedding studies suggest that the mucus possibly serves as a barrier which is passed selectively only by a small amount of lectins or lectin-carbohydrate complexes. Lectin-carbohydrate interactions may play a role in recognition phenomena on the plasmalemmata of the taste bud sensory cells. Recognition processes directed to bacteria or viruses should be considered as well.
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PMID:Electron microscopic demonstration of lectin binding sites in the taste buds of the European catfish Silurus glanis (Teleostei). 227 57

Hamsters exposed to an intratracheal instillation of human neutrophil elastase (HNE) accumulate an abnormally high number of secretory granules in bronchial but not tracheal epithelial cells. We employed lectin cytochemistry to investigate possible differences in the epithelial cell surface glycoconjugate layer in trachea compared to bronchus which might explain the regional dissimilarity in response to HNE. Portions of glutaraldehyde-fixed trachea and bronchi were incubated in one of several ferritin-labeled lectins prior to embedding for transmission electron microscopy. Lectins from Ricinus communis, Helix pomatia, and Triticum vulgaris bound to the surface of tracheal secretory cells in moderate to profuse amounts, while most bronchial secretory cells showed little or no label with these lectins. Gold-labeled Helix pomatia agglutinin (HPA), a lectin specific for secretory cells, showed a decrease in surface binding to all tracheal secretory cell types within 2 h of HNE instillation, compared to saline controls. In contrast, the majority of bronchial secretory cells showed an HNE-induced increase in surface label from extremely low levels in saline controls. The low levels of lectin binding to bronchial cells, in contrast to the trachea, may indicate the lack of a protective surface glycoconjugate coat, thus explaining the vulnerability of these cells to HNE. The rise in number of accessible HPA binding sites on the surface of bronchial secretory cells exposed to HNE may represent an important event in the pathologic accumulation of secretory granules by these cells.
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PMID:Lectin cytochemistry reveals differences between hamster trachea and bronchus in the composition of epithelial surface glycoconjugates and in the response of secretory cells to neutrophil elastase. 236 36

Distribution of alpha-D-mannose and alpha-D-glucose residues of glycoconjugates in axons of sciatic nerves of 24-month old rats of Wistar strains was studied by concanavalin-A-ferritin conjugate. In some of axons there were cumulations of ferritin molecules in agglomerates of various size with polarization of the phenomenon at preserved integrity of myelin sheath. In other cases the concentration of a large number of lectin binding sites was established in the region of the degenerating part of myelin sheath, engrossed in the axon cylinder. The changes in the distribution of carbohydrate residues in the axoplasm of some of the fibers are discussed in connection with the occurring axonal atrophy in fibers of peripheral nerves of old rats.
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PMID:[Cytochemical localization of concanavalin A binding sites in the peripheral nerve axons of old rats]. 239 17

Complex carbohydrates in secretory granules and at the apical cell surface of mouse gastric mucoid cells were studied during embryogenesis and in the early postnatal period by various cytochemical methods; the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) and tannic acid-uranyl acetate (TA-UA) procedures made neutral mucosubstances (NMS) visible, whereas the hexose residues of glycoconjugates were identified using WGA-, RCA II- and ConA-ferritin. The glycocalyx was stained with ruthenium red (RR). During differentiation of the embryonic mucoid cells the number of secretory granules increased in parallel to the increase in their carbohydrate component. NMS-stainable parts in secretory granules also had binding sites for the conjugates RCA II- and WGA-ferritin, but the binding of ConA could not be identified. The increasing quantity of NMS in secretory granules was correlated with the increased amount of PA-TCH-SP and TA-UA positive substances in the apical glycocalyx only in 14- and 18-day-old embryos. The observed uniform affinity for RR and lectin conjugates in all analysed developmental stages remains to be explained.
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PMID:The carbohydrates of secretory granules and the glycocalyx in developing mucoid cells. 241 10

A method involving rapid freezing followed by substitution fixation was developed, using acrolein as a fixative. This was then applied to several cytochemical stainings, and showed well preserved and clear cell structures. Membranes were apparently negatively stained and the ultrastructure of mitochondria, rough endoplasmic reticulum and Golgi apparatus was clearly discernible. The mitochondrial and cytoplasmic matrices were stained rather densely compared with routine chemically fixed preparations, implying a good preservation of matrix substances. Periodic acid-thiocarbohydrazide-silver proteinate staining was applied to the present method. The mucous granules of surface covering epithelial cells indicated fine staining of bipartite structure and the Golgi apparatus of mucous cells showed clear staining differences based on polarity. Postembedding lectin-ferritin and immunocytochemical stainings were applicable to the present preparations and stable stainings of secretory granules were obtained. A low temperature embedding material, Lowicryl K4M, was also examined. The cell preservation of these samples was not as good as those embedded in Epon, but the rough endoplasmic reticulum and Golgi apparatus of chief cells were stained with anti-pepsinogen antibody as were the secretory granules. The present method was also applicable to light microscopy.
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PMID:Application of rapid freezing followed by freeze-substitution acrolein fixation for cytochemical studies of the rat stomach. 241 93


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