Search results for "Microscopy"
showing 10 items of 3390 documents
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.
Intracellular route of canine parvovirus entry.
1998
ABSTRACT The present study was designed to investigate the endocytic pathway involved in canine parvovirus (CPV) infection. Reduced temperature (18°C) or the microtubule-depolymerizing drug nocodazole was found to inhibit productive infection of canine A72 cells by CPV and caused CPV to be retained in cytoplasmic vesicles as indicated by immunofluorescence microscopy. Consistent with previously published results, these data indicate that CPV enters a host cell via an endocytic route and further suggest that microtubule-dependent delivery of CPV to late endosomes is required for productive infection. Cytoplasmic microinjection of CPV particles was used to circumvent the endocytosis and membr…
The Yeast RNA Polymerase II-associated Factor Iwr1p Is Involved in the Basal and Regulated Transcription of Specific Genes
2009
RNA polymerase II (RNA pol II) is a multisubunit enzyme that requires many auxiliary factors for its activity. Over the years, these factors have been identified using both biochemical and genetic approaches. Recently, the systematic characterization of protein complexes by tandem affinity purification and mass spectroscopy has allowed the identification of new components of well established complexes, including the RNA pol II holoenzyme. Using this approach, a novel and highly conserved factor, Iwr1p, that physically interacts with most of the RNA pol II subunits has been described in yeast. Here we show that Iwr1p genetically interacts with components of the basal transcription machinery …
Automatic Counting of Intra-Cellular Ribonucleo-Protein Aggregates in Saccharomyces cerevisiae Using a Textural Approach.
2019
AbstractIn the context of microbiology, recent studies show the importance of ribonucleo-protein aggregates (RNPs) for the understanding of mechanisms involved in cell responses to specific environmental conditions. The assembly and disassembly of aggregates is a dynamic process, the characterization of the stage of their evolution can be performed by the evaluation of their number. The aim of this study is to propose a method to automatically determine the count of RNPs. We show that the determination of a precise count is an issue by itself and hence, we propose three textural approaches: a classical point of view using Haralick features, a frequency point of view with generalized Fourier…
Selective targeting of avidin/mannose 6-phosphate receptor chimeras to early or late endosomes
2000
Summary In this study we have used the Semliki forest virus expression system to transiently express chimeric proteins that contain transmembrane and cytoplasmic domains of the cation-independent mannose 6-phosphate receptor (CI-MPR) fused to chicken avidin. Immunofluorescence and electron microscopy studies showed that the chimeric protein with the entire cytoplasmic domain of CI-MPR was transported to late endosomes, where it accumulated. We made use of the biotin-binding capacity of lumenal avidin, and found that, in agreement with this distribution, the chimeric protein could be labelled with biotinylated HRP endocytosed for a long, but not a brief, period of time. However, truncation o…
Amyloid Precursor-like Protein 1 Influences Endocytosis and Proteolytic Processing of the Amyloid Precursor Protein
2005
Ectodomain shedding of the amyloid precursor protein (APP) is a key regulatory step in the generation of the Alzheimer disease amyloid beta peptide (Abeta). The molecular mechanisms underlying the control of APP shedding remain little understood but are in part dependent on the low density lipoprotein receptor-related protein (LRP), which is involved in APP endocytosis. Here, we show that the APP homolog APLP1 (amyloid precursor-like protein 1) influences APP shedding. In human embryonic kidney 293 cells expression of APLP1 strongly activated APP shedding by alpha-secretase and slightly reduced beta-secretase cleavage. As revealed by domain deletion analysis, the increase in APP shedding re…
Cadherin 23 is a component of the transient lateral links in the developing hair bundles of cochlear sensory cells
2005
AbstractCadherin 23 is required for normal development of the sensory hair bundle, and recent evidence suggests it is a component of the tip links, filamentous structures thought to gate the hair cells' mechano-electrical transducer channels. Antibodies against unique peptide epitopes were used to study the properties of cadherin 23 and its spatio-temporal expression patterns in developing cochlear hair cells. In the rat, intra- and extracellular domain epitopes are readily detected in the developing hair bundle between E18 and P5, and become progressively restricted to the distal tip of the hair bundle. From P13 onwards, these epitopes are no longer detected in hair bundles, but immunoreac…
Baculovirus capsid display: a novel tool for transduction imaging
2003
Baculoviruses are enveloped insect viruses that can carry large quantities of foreign DNA in their genome. Baculoviruses have proved to be very promising gene therapy vectors but little is known about their transduction mechanisms in mammalian cells. We show in this study that Autographa californica multiple nuclear polyhedrosis virus capsid is compatible with the incorporation of desired proteins in large quantities. Fusions can be made to the N-terminus or C-terminus of the major capsid protein vp39 without compromising the viral titer or functionality. As an example of the baculovirus capsid display we show a tracking of the baculovirus transduction in mammalian cells by an enhanced gree…
Human NK cells selective targeting of colon cancer-initiating cells: a role for natural cytotoxicity receptors and MHC class I molecules
2013
Abstract Tumor cell populations have been recently proposed to be composed of two compartments: tumor-initiating cells characterized by a slow and asymmetrical growth, and the “differentiated” cancer cells with a fast and symmetrical growth. Cancer stem cells or cancer-initiating cells (CICs) play a crucial role in tumor recurrence. The resistance of CICs to drugs and irradiation often allows them to survive traditional therapy. NK cells are potent cytotoxic lymphocytes that can recognize tumor cells. In this study, we have analyzed the NK cell recognition of tumor target cells derived from the two cancer cell compartments of colon adenocarcinoma lesions. Our data demonstrate that freshly p…