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Genetics Aug 1994Mapping and complementation analysis with 17 phototaxis mutations has established 11 complementation groups phoA-phoK distributed over six linkage groups. Statistical...
Mapping and complementation analysis with 17 phototaxis mutations has established 11 complementation groups phoA-phoK distributed over six linkage groups. Statistical calculations from the complementation data yielded 17 as the maximum likelihood estimate of the number of pho genes assuming all loci are equally mutable. Most of the phototaxis mutants were found to exhibit bimodal phototaxis and all were found to be impaired in positive thermotaxis supporting convergence of the photosensory and thermosensory pathways. The thermotaxis mutant HPF228 was unaltered in phototaxis suggesting that the mutation in this strain affects a gene product whose site of action is before the convergence of the two pathways. Other phenotypes such as multiple tip formation by aggregates, stumpy fruiting bodies with short or absent stalks and short migration were associated with some pho alleles suggesting multiple biological roles for some gene products important in phototransduction.
Topics: Alleles; Animals; Cell Movement; Dictyostelium; Genetic Complementation Test; Genetic Linkage; Likelihood Functions; Monte Carlo Method; Phenotype
PubMed: 7982578
DOI: 10.1093/genetics/137.4.977 -
Society of General Physiologists Series 1990
Review
Topics: Animals; Cell Aggregation; Dictyostelium; GTP-Binding Proteins; Signal Transduction
PubMed: 2116034
DOI: No ID Found -
Medicina 2010
Topics: Animals; Dictyostelium; Humans; Models, Biological
PubMed: 20679065
DOI: No ID Found -
BioEssays : News and Reviews in... Oct 1986
Review
Topics: Cell Movement; Dictyostelium; Morphogenesis
PubMed: 3333470
DOI: 10.1002/bies.950050403 -
Molecular Biology of the Cell Dec 1999We have developed a fluorimetric assay with the use of the dye FM1-43 to determine the rate at which Dictyostelium amoebae endocytose their surface membrane. Our results...
We have developed a fluorimetric assay with the use of the dye FM1-43 to determine the rate at which Dictyostelium amoebae endocytose their surface membrane. Our results show that they do so about once each 4-10 min. A clathrin null mutant takes its surface up only approximately 30% more slowly, showing that this membrane uptake cannot be caused by clathrin-coated vesicles. Surprisingly, Ax2 and its parent, NC4, which differ in their rates of fluid-phase internalization by approximately 60-fold, take up their surfaces at the same rates. These results show that, in axenic cells, the uptake of fluid and of surface area are separate processes. The large activity of this new endocytic cycle in both Ax2 and NC4 amoebae appears capable of delivering sufficient new surface area to advance the cells' fronts during migration.
Topics: Animals; Cell Membrane; Clathrin; Dictyostelium; Endocytosis; Fluorescent Dyes; Mutation; Pyridinium Compounds; Quaternary Ammonium Compounds
PubMed: 10588667
DOI: 10.1091/mbc.10.12.4419 -
Methods in Molecular Biology (Clifton,... 2018Dictyostelium discoideum has proven to be an excellent model to study amoeboid cell migration. During their life cycle, Dictyostelium cells exhibit distinct modes of...
Dictyostelium discoideum has proven to be an excellent model to study amoeboid cell migration. During their life cycle, Dictyostelium cells exhibit distinct modes of motility. Individual growth-phase cells explore new territories by random cell migration using the core cell motility machinery, but they can also hunt bacteria by detection and chemotaxis toward the by-product folate. After depletion of nutrients, the cells initiate a developmental program allowing streaming of the cells into aggregation centers by chemotaxis toward cAMP and by cell-to-cell adhesion. Subsequent development is associated with complex rotational movement of the compacted aggregates to drive cell type specific sorting, which in turn is necessary for terminal culmination and formation of fruiting bodies. Here we describe a protocol for the analyses of cell motility of vegetative Dictyostelium cells in unconfined and mechanically confined settings.
Topics: Cell Movement; Chemotaxis; Cyclic AMP; Dictyostelium; Signal Transduction
PubMed: 29526008
DOI: 10.1007/978-1-4939-7701-7_24 -
Cellular Microbiology Nov 2011In unicellular amoebae, such as Dictyostelium discoideum, bacterial phagocytosis is a food hunting device, while in higher organisms it is the first defence barrier...
In unicellular amoebae, such as Dictyostelium discoideum, bacterial phagocytosis is a food hunting device, while in higher organisms it is the first defence barrier against microbial infection. In both cases, pathogenic bacteria exploit phagocytosis to enter the cell and multiply intracellularly. Salmonella typhimurium, the agent of food-borne gastroenteritis, is phagocytosed by both macrophages and Dictyostelium cells. By using cell biological assays and global transcriptional analysis with DNA microarrays covering the Dictyostelium genome, we show here that S. typhimurium is pathogenic for Dictyostelium cells. Depending on the degree of virulence, which in turn depended on bacterial growth conditions, Salmonella could kill Dictyostelium cells or inhibit their growth and development. In the early phase of infection in non-nutrient buffer, the ingested bacteria escaped degradation, induced a starvation-like transcriptional response but inhibited selectively genes required for chemotaxis and aggregation. This way differentiation of the host cells into spore and stalk cells was blocked or delayed, which in turn is likely to be favourable for the establishment of a replicative niche for Salmonella. Inhibition of the aggregation competence and chemotactic streaming of aggregation-competent cells in the presence of Salmonella suggests interference with cAMP signalling.
Topics: Cell Survival; Cyclic AMP; Dictyostelium; Gene Expression Profiling; Microarray Analysis; Phagocytosis; Salmonella typhimurium; Signal Transduction
PubMed: 21824247
DOI: 10.1111/j.1462-5822.2011.01662.x -
Nucleic Acids Research Jul 1988Dictyostelium discoideum is of increasing interest as a model eukaryotic cell because its many attributes have recently been expanded to include improved genetic and...
Dictyostelium discoideum is of increasing interest as a model eukaryotic cell because its many attributes have recently been expanded to include improved genetic and biochemical manipulability. The ability to transform Dictyostelium using drug resistance as a selectable marker (1) and to gene target by high frequency homologous integration (2) makes this organism particularly useful for molecular genetic approaches to cell structure and function. Given this background, it becomes important to analyze the codon preference used in this organism. Dictyostelium displays a strong and unique overall codon preference. This preference varies between different coding regions and even varies between coding regions from the same gene family. The degree of codon preference may be correlated with expression levels but not with the developmental time of expression of the gene product. The strong codon preference can be applied to identify coding regions in Dictyostelium DNA and aid in the design of oligonucleotide probes for cloning Dictyostelium genes.
Topics: Codon; Dictyostelium; Gene Expression Regulation; Genes; RNA, Messenger
PubMed: 3399410
DOI: 10.1093/nar/16.14.6617 -
Journal of Visualized Experiments : JoVE Sep 2018Large-scale non-specific fluid uptake by macropinocytosis is important for the proliferation of certain cancer cells, antigen sampling, host cell invasion and the spread...
Large-scale non-specific fluid uptake by macropinocytosis is important for the proliferation of certain cancer cells, antigen sampling, host cell invasion and the spread of neurodegenerative diseases. The commonly used laboratory strains of the amoeba Dictyostelium discoideum have extremely high fluid uptake rates when grown in nutrient medium, over 90% of which is due to macropinocytosis. In addition, many of the known core components of mammalian macropinocytosis are also present, making it an excellent model system for studying macropinocytosis. Here, the standard technique to measure internalized fluid using fluorescent dextran as a label is adapted to a 96-well plate format, with the samples analyzed by flow cytometry using a high-throughput sampling (HTS) attachment. Cells are fed non-quenchable fluorescent dextran for a pre-determined length of time, washed by immersion in ice-cold buffer and detached using 5 mM sodium azide, which also stops exocytosis. Cells in each well are then analyzed by flow cytometry. The method can also be adapted to measure membrane uptake and phagocytosis of fluorescent beads or bacteria. This method was designed to allow measurement of fluid uptake by Dictyostelium in a high-throughput, labor and resource efficient manner. It allows simultaneous comparison of multiple strains (e.g. knockout mutants of a gene) and conditions (e.g. cells in different media or treated with different concentrations of inhibitor) in parallel and simplifies time-courses.
Topics: Animals; Dictyostelium; Flow Cytometry; Pinocytosis
PubMed: 30247467
DOI: 10.3791/58434 -
Nature Protocols 2007Dictyostelium discoideum, a unicellular organism capable of developing into a multicellular structure, is a powerful model system to study a variety of biological...
Dictyostelium discoideum, a unicellular organism capable of developing into a multicellular structure, is a powerful model system to study a variety of biological processes. Because it is inexpensive and relatively easy to grow, Dictyostelium is also frequently used in teaching laboratories. Here we describe conditions for successfully growing and developing Dictyostelium cells and methods for long-term storage of Dictyostelium amoebae and spores.
Topics: Animals; Cell Movement; Culture Techniques; Dictyostelium; Phototropism
PubMed: 17545967
DOI: 10.1038/nprot.2007.178