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Traffic (Copenhagen, Denmark) Jan 2003The endocytic pathway in Dictyostelium appears as a short circuit between endocytosis and exocytosis. Within the hour that elapses between internalization of nutrients... (Review)
Review
The endocytic pathway in Dictyostelium appears as a short circuit between endocytosis and exocytosis. Within the hour that elapses between internalization of nutrients and release of remnants, digestion by lysosomal enzymes occurs. Meanwhile, the maturing endosome undergoes a complex series of fusion and fission events, which change its character profoundly and which are far from being fully understood. This review attempts to order the dynamic events into a sequence of stages that is most consistent with present knowledge.
Topics: Animals; Dictyostelium; Endocytosis; Endosomes
PubMed: 12535269
DOI: 10.1034/j.1600-0854.2003.40101.x -
Development Genes and Evolution Feb 2014Dictyostelium discoideum is a facultative multicellular amoebozoan with cellulose in the stalk and spore coat of its fruiting body as well as in the extracellular matrix...
Dictyostelium discoideum is a facultative multicellular amoebozoan with cellulose in the stalk and spore coat of its fruiting body as well as in the extracellular matrix of the migrating slug. The organism also harbors a number of cellulase genes. One of them, cbhA, was identified as a candidate cellobiohydrolase gene based on the strong homology of its predicted protein product to fungal cellobiohydrolase I (CBHI). Expression of the cbhA was developmentally regulated, with strong expression in the spores of the mature fruiting body. However, a weak but detectable level of expression was observed in the extracellular matrix at the mound - tipped finger stages, in prestalk O cells, and in the slime sheath of the migrating slug - late culminant stages. A null mutant of the cbhA showed almost normal morphology. However, the developmental timing of the mutant was delayed by 2-4 h. When a c-Myc epitope-tagged CbhA was expressed, it was secreted into the culture medium and was able to bind crystalline cellulose. The CbhA-myc protein was glycosylated, as demonstrated by its ability to bind succinyl concanavalin A-agarose. Moreover, conditioned medium from the cbhA-myc (oe) strain displayed 4-methylumbelliferyl β-D-cellobioside (4-MUC) digesting activity in Zymograms in which conditioned medium was examined via native-polyacrylamide gel electrophoresis or spotted on an agar plate containing 4-MUC, one of the substrates of cellobiohydrolase. Taken together, these findings indicate that Dictyostelium CbhA is an orthologue of CBH I that is required for a normal rate of development.
Topics: Cellulose; Cellulose 1,4-beta-Cellobiosidase; Dictyostelium; Mutation; Phenotype
PubMed: 24240571
DOI: 10.1007/s00427-013-0460-x -
Cell Jun 1983DIF is an endogenous extracellular signal that may control differentiation of D. discoideum cells. It is a dialyzable, lipid-like factor that induces stalk cell...
DIF is an endogenous extracellular signal that may control differentiation of D. discoideum cells. It is a dialyzable, lipid-like factor that induces stalk cell formation among isolated amebae incubated in vitro with cAMP. To examine the consequences of DIF deprivation, we have isolated several mutant strains that are impaired in DIF accumulation, and whose inability to make stalk cells in vitro and during normal development on agar can be corrected by the addition of exogenous DIF. Little DIF is made by the mutants, and morphological development on agar stops after the cells have aggregated, but before a slug forms. In these DIF-deprived conditions, prespore cells can differentiate, but prestalk cells cannot.
Topics: Cell Differentiation; Dictyostelium; Morphogenesis; Mutation
PubMed: 6861203
DOI: 10.1016/0092-8674(83)90421-x -
Signaling molecules involved in the transition of growth to development of Dictyostelium discoideum.Indian Journal of Experimental Biology Mar 2007The social amoeba Dictyostelium discoideum, a powerful paradigm provides clear insights into the regulation of growth and development. In addition to possessing complex... (Review)
Review
The social amoeba Dictyostelium discoideum, a powerful paradigm provides clear insights into the regulation of growth and development. In addition to possessing complex individual cellular functions like a unicellular eukaryote, D. discoideum cells face the challenge of multicellular development. D. discoideum undergoes a relatively simple differentiation process mainly by cAMP mediated pathway. Despite this relative simplicity, the regulatory signaling pathways are as complex as those seen in metazoan development. However, the introduction of restriction-enzyme-mediated integration (REMI) technique to produce developmental gene knockouts has provided novel insights into the discovery of signaling molecules and their role in D. discoideum development. Cell cycle phase is an important aspect for differentiation of D. discoideum, as cells must reach a specific stage to enter into developmental phase and specific cell cycle regulators are involved in arresting growth phase genes and inducing the developmental genes. In this review, we present an overview of the signaling molecules involved in the regulation of growth to differentiation transition (GDT), molecular mechanism of early developmental events leading to generation of cAMP signal and components of cAMP relay system that operate in this paradigm.
Topics: Animals; Cell Cycle; Culture Media, Conditioned; Dictyostelium; Signal Transduction
PubMed: 17373365
DOI: No ID Found -
Biochemistry and Cell Biology =... Jul 1989During the first 24 h of sexual development in Dictyostelium discoideum, three sequential events of membrane fusion occur: gamete fusion, pronuclear fusion, and... (Review)
Review
During the first 24 h of sexual development in Dictyostelium discoideum, three sequential events of membrane fusion occur: gamete fusion, pronuclear fusion, and phagocytosis. The early events of sexual development are regulated by a diverse group of endogenous molecules: (i) a volatile sexual pheromone, (ii) a protein cell fusion inducing factor (CFIF), (iii) a low molecular weight autoinhibitor, (iv) and cyclic AMP. CFIC enhances cell fusion while the autoinhibitor and cyclic AMP both inhibit the event. Both extracellular and intracellular calcium ions are essential for cell and pronuclear fusion. Pharmacological analyses show that the intracellular functions of the divalent cation in these processes are mediated by calmodulin. The autoinhibitor appears to function by inhibiting calmodulin activity. Glucose, mannose, and N-acetylglucosamine containing glycoproteins have been shown to function in both cell fusion and phagocytosis. The interplay between all of these diverse molecules is examined and a review of all of the recent literature is presented.
Topics: Cell Membrane; Dictyostelium; Membrane Fusion
PubMed: 2675932
DOI: 10.1139/o89-050 -
Genome Biology 2007A new study has used parallel filming to record the development of 2,000 Dictyostelium mutants, and clustered them into related groups using morphological staging and... (Review)
Review
A new study has used parallel filming to record the development of 2,000 Dictyostelium mutants, and clustered them into related groups using morphological staging and wavelet analysis of aggregation patterns.
Topics: Animals; Dictyostelium; Morphogenesis; Motion Pictures; Phenotype
PubMed: 17666111
DOI: 10.1186/gb-2007-8-7-220 -
The International Journal of... Jun 1994Free-living cells of Dictyostelium discoideum aggregate to form a slug-shaped cell mass and differentiate into prestalk and prespore cells. The differentiation of... (Review)
Review
Free-living cells of Dictyostelium discoideum aggregate to form a slug-shaped cell mass and differentiate into prestalk and prespore cells. The differentiation of prespore cells is characterized by expression of Dp87 gene, the earliest event of prespore differentiation. It encodes a protein which first appears in ER of aggregating cells in a precursor form, is then translocated to prespore vacuoles and modified to a mature form and finally exocytosed to constitute the sorus matrix. The transcription of Dp87 is regulated by the cis-acting region consisting of positive, prespore-specific, negative, non-prespore-specific and positive, cell-type-non-specific elements. Cells expressing Dp87 appear at random in early aggregation streams and centers and then sort out to the posterior part of the slug. Intercellular signals required for prestalk and prespore differentiation were investigated by incubation at a low cell density of disaggregated cells. cAMP is inhibitory at the first and second stages of prespore differentiation, while it is required at the third stage. The stalk differentiation is divided into four stages: cAMP is required at the second stage and differentiation inducing factor (DIF) at the third stage, where a low molecular weight secretory substance is also required. At the third stage, cAMP inhibits both ecmA and ecmB expression, while 8-Br-cAMP specifically induces ecmB and maturation of prestalk to stalk cells. The relationship between the differentiation tendency of preaggregative cells and the cell-cycle phase at the initiation of development was studied by the use of cells synchronized for growth by a temperature-shift method.(ABSTRACT TRUNCATED AT 250 WORDS)
Topics: Animals; Cell Cycle; Cell Differentiation; Cyclic AMP; Dictyostelium; Gene Expression Regulation, Developmental; Genes, Fungal; Genes, Protozoan; Signal Transduction; Spores, Fungal
PubMed: 7981039
DOI: No ID Found -
Annual Review of Biochemistry 1987
Review
Topics: Cyclic AMP; Dictyostelium; Genes, Fungal; Morphogenesis
PubMed: 3039908
DOI: 10.1146/annurev.bi.56.070187.004225 -
The Journal of Cell Biology Jun 1982We describe six motility mutants of Dictyostelium discoideum in this report. They were identified among a group of temperature-sensitive growth (Tsg) mutants that had...
We describe six motility mutants of Dictyostelium discoideum in this report. They were identified among a group of temperature-sensitive growth (Tsg) mutants that had been previously isolated using an enrichment for phagocytosis-defective cells. The Tsg mutants were screened for their ability to produce tracks on gold-coated cover slips, and several strains were found that were temperature-sensitive for migration in this assay. Analysis of spontaneous Tsg+ revertants of 10 migration-defective strains identified six strains that co-reverted the Tsg and track formation phenotypes. Characterization of these six strains indicated that they were defective at restrictive temperature in track formation, phagocytosis of bacteria, and pseudopodial and filopodial activity, while retaining normal rates of oxygen consumption and viability. Because they had lost this group of motile capabilities, these strains were designated motility mutants. The Tsg+ revertants of these mutants, which coordinately recovered all of the motile activities, were found at frequencies consistent with single genetic events. Analysis of the motility mutants and their revertants suggests a relationship between the motility mutations in some of these strains and genes affecting axenic growth.
Topics: Dictyostelium; Movement; Mutation; Oxygen Consumption; Phagocytosis; Phenotype; Temperature
PubMed: 7118999
DOI: 10.1083/jcb.93.3.705 -
Methods in Molecular Biology (Clifton,... 2006Both prokaryote and eukaryote cells can sense and move up chemical concentration gradients (chemotax). As a means of finding food sources during vegetative growth,...
Both prokaryote and eukaryote cells can sense and move up chemical concentration gradients (chemotax). As a means of finding food sources during vegetative growth, Dictyostelium discoideum naturally chemotaxes toward chemicals released by bacteria. As part of its developmental life cycle, D. discoideum chemotaxes towards cAMP. This chapter describes protocols for using Dictyostelium to understand the cell biology behind and the signaling events necessary for eukaryotic amoeboid chemotaxis. The chapter includes analyses of random cell motility, directed motility up chemical gradients, cellular responses to uniform chemoattractant exposure, and the utility of fluorescent probes for chemotaxis signaling events. Random cell motility in the absence of chemoattractant is analyzed to decipher the properties of self-organizing pseudopodia extension and retraction. Monitoring chemotaxis toward cAMP and folate allows the determination of signaling events required for sensing a chemical gradient and moving in a directed, persistent manner up the gradient. Uniform chemoattractant exposure is employed to elucidate the immediate intracellular responses to chemoattractant stimulation. Finally, analyzing cells expressing fluorescent fusion proteins is vital to elucidating the location of signaling events during chemotaxis.
Topics: Animals; Biological Assay; Cell Movement; Chemotaxis; Cyclic AMP; Dictyostelium; Folic Acid; Pseudopodia; Signal Transduction
PubMed: 16957303
DOI: 10.1385/1-59745-144-4:393