The relationship between cytoplasmic pH (pHi) and prestalk/prespore differentiation in the cellular slime mould Dictyostelium discoideum was investigated by: (1) comparing the pHi of prestalk and prespore cells, and (2) examining the effects on pHi of weak acids, weak bases and proton-pump inhibitors. These substances are known to affect the spore-to-stalk ratio. The pHj of dissociated slug cells was measured by microfluorometry using a pH-sensitive fluorescence dye, carboxyfluorescein.. There was a slight but significant difference in pH, between prestalk cells (7.38 ± 0.09) and prespore cells (7.49 ± 0.03), and prestalk cells were more sensitive to acid load than prespore cells. In addition, weak acids and proton-pump inhibitors, which promote prestalk differentiation, significantly lowered pHi whereas weak bases, which induce prespore differentiation, elevated pHi. However, differentiation inducing factor (DIF), an endogenous inducer of stalk differentiation, caused only a slight and ...
The haploid social amoeba Dictyostelium discoideum is a well-defined model organism which is amenable to diverse biochemical, cell biological, and molecular genetic approaches. The similarities between the Dictyostelium and mammalian cells extend to membrane trafficking, endocytic transit and sorting events. Therefore, Dictyostelium opens the exciting possibility of investigating and manipulating both sides of the Legionella-host interaction. The intrinsic features of Dictyostelium and a set of well-established molecular tools enabled the authors to prove that Dictyostelium is a representative cellular model for Legionella infection. The research areas presented in this chapter include the analysis of the transcriptional host cell response to Legionella infection and the use of custom tailored Dictyostelium mutant cells to identify determinants of susceptibility and resistance. In order to describe the transcriptional host cell response to Legionella infection, the authors employed DNA-microarrays which
Macroautophagy is a mechanism employed by eukaryotic cells to recycle non-essential cellular components during starvation, differentiation, and development. Two conjugation reactions related to ubiquitination are essential for autophagy: Apg12p conjugation to Apg5p, and Apg8p conjugation to the lipid phosphatidylethanolamine. These reactions require the action of the E1-like enzyme, Apg7p, and the E2-like enzymes, Apg3p and Apg10p. In Dictyostelium, development is induced by starvation, conditions under which autophagy is required for survival in yeast and plants. We have identified Dictyostelium homologues of 10 budding yeast autophagy genes. We have generated mutations in apg5 and apg7 that produce defects typically associated with an abrogation of autophagy. Mutants are not grossly affected in growth, but survival during nitrogen starvation is severely reduced. Starved mutant cells show little turnover of cellular constituents by electron microscopy, whereas wild-type cells show significant ...
Abstract: Myosin heavy chain kinase (MHCK) A phosphorylates mapped sites at the C-terminal tail of Dictyostelium myosin II heavy chain, driving disassembly of myosin filaments both in vitro and in vivo. MHCK A is organized into three functional domains that include an N-terminal coiled-coil region, a central kinase catalytic domain unrelated to conventional protein kinases, and a WD repeat domain at the C terminus. MHCK B is a homologue of MHCK A that possesses structurally related catalytic and WD repeat domains. In the current study, we explored the role of the WD repeat domains in defining the activities of both MHCK A and MHCK B using recombinant bacterially expressed truncations of these kinases either with or without their WD repeat domains. We demonstrate that substrate targeting is a conserved function of the WD repeat domains of both MHCK A and MHCK B and that this targeting is specific forDictyostelium myosin II filaments. We also show that the mechanism of targeting involves direct ...
The social amoeba Dictyostelium discoideum is a well-established model organism to study the interaction between bacteria and phagocytes. In contrast, research using D. discoideum as a host model for fungi is rare. We describe a comprehensive study, which uses D. discoideum as a host model system to investigate the interaction with apathogenic (Saccharomyces cerevisiae) and pathogenic (Candida sp.) yeast. We show that Dictyostelium can be co-cultivated with yeasts on solid media, offering a convenient test to study the interaction between fungi and phagocytes. We demonstrate that a number of D. discoideum mutants increase (atg1-, kil1-, kil2-) or decrease (atg6-) the ability of the amoebae to predate yeast cells. On the yeast side, growth characteristics, reduced phagocytosis rate, as well as known virulence factors of C. albicans (EFG1, CPH1, HGC1, ICL1) contribute to the resistance of yeast cells against predation by the amoebae. Investigating haploid C. albicans strains, we suggest using the amoebae
By analysing the growth kinetics of Dictyostelium discoideum amoebae in varying combinations of the components of the nutrient medium HL-5 (Cocucci & Sussman, 1970), we have demonstrated that Dictyostelium amoebae enter stationary phase when they deplete the medium of one or more nutrient components. However, if the medium of a stationary phase culture is supplemented with any of the initial components of HL-5 medium and even when supplemented with all components of HL-5 medium, it does not support the growth of freshly inoculated cells, indicating that stationary phase cultures produce a potent growth inhibitor. The possible function of this inhibitor is discussed.. ...
In an earlier paper (Tang & Othmer 1994 Math. Biosci 120, 25-76), we developed a G-protein-based model for signal transduction in the cellular slime mould Dictyostelium discoideum and showed that it can account for the results from perfusion experiments done by Devreotes and coworkers (Devreotes et al. 1979 J. Cell. 80, 300-309; Devreotes & Steck 1979 J. Cell Biol. 80, 300-309; Dinauer et al. 1980 J. Cell Biol. 86, 537-561). The primary experimental observables are the amounts of cAMP secreted and the time scale of adaptation in response to various stimuli, and we showed that the predictions of the model agree well with the observations. Adaptation in the model arises from dual receptor-mediated pathways, one of which produces a stimulatory G protein Gs and the other of which produces an inhibitory G protein Gt. In this paper we use the model to simulate the suspension experiments of Gerisch & Wick (1975 Biochem. biophys. Res. Commun. 65, 364-370) and the experiments done in cell cultures on ...
The cellular slime mold Dictyostelium discoideumlives in the soil where it feeds on bacteria. Exhaustion of the food supply induces cell aggregation. Subsequently, cells differentiate to two cell...
Abstract: Studies in Dictyostelium discoideum have established that the cycle of myosin II bipolar filament assembly and disassembly controls the temporal and spatial localization of myosin II during critical cellular processes, such as cytokinesis and cell locomotion. Myosin heavy chain kinase A (MHCK A) is a key enzyme regulating myosin II filament disassembly through myosin heavy chain phosphorylation in Dictyostelium. Under various cellular conditions, MHCK A is recruited to actin-rich cortical sites and is preferentially enriched at sites of pseudopod formation, and thus MHCK A is proposed to play a role in regulating localized disassembly of myosin II filaments in the cell. MHCK A possesses an aminoterminal coiled-coil domain that participates in the oligomerization, cellular localization, and actin binding activities of the kinase. In the current study, we show that the interaction between the coiled-coil domain of MHCK A and filamentous actin leads to an ~40-fold increase in the initial ...
At the aggregation stage of Dictyostelium discoideum development, a cell surface glycoprotein of Mr 80,000 (gp80) has been found to mediate the EDTA-resistant type of cell-cell adhesion via homophilic interaction (Siu, C.-H., A. Cho, and A. H. C. Choi. 1987. J. Cell Biol. 105:2523-2533). To investigate the structure-function relationships of gp80, we have isolated full length cDNA clones for gp80 and determined the DNA sequence. The deduced structure of gp80 showed three major domains. An amino-terminal globular domain composed of the bulk of the protein is supported by a short stalk region, which is followed by a membrane anchor at the carboxy terminus. Structural analysis suggested that the cell-binding domain of gp80 resides within the globular domain near the amino terminus. To investigate the relationship of the cell-binding activity to this region of the polypeptide, three protein A/gp80 (PA80) gene fusions were constructed using the expression vector pRIT2T. These PA80 fusion proteins ...
The traditional view of RNA being merely an intermediate in the transfer of genetic information, as mRNA, spliceosomal RNA, tRNA, and rRNA, has become outdated. The recent discovery of numerous regulatory RNAs with a plethora of functions in biological processes has truly revolutionized our understanding of gene regulation. Tiny RNAs such as microRNAs and small interfering RNAs play vital roles at different levels of gene control. Small nucleolar RNAs are much more abundant than previously recognized, and new functions beyond processing and modification of rRNA have recently emerged. Longer non-coding RNAs (ncRNAs) can also have important regulatory roles in the cell, e.g., antisense RNAs that control their target mRNAs. The majority of these important findings arose from analyses in various model organisms. In this review, we focus on ncRNAs in the social amoeba Dictyostelium discoideum. This important genetically tractable model organism has recently received renewed attention in terms of ...
Eukaryotic amoebae Dictyostelium discoideum (referred as Dictyostelium) in the vegetative state forage on bacteria by following gradients of folic acid (FA), a by-product of bacterial metabolism [1,2]. It is currently believed that Dictyostelium measure chemical gradients directly by monitoring the distribution of the occupied chemoattractant receptors. These cells can detect concentration differences as low as a few per cent across their cell bodies [3-8] and it is currently an open question what exactly limits this process. Previously, the receptor-ligand binding fluctuations were suggested as the limiting factor, which remains a possibility because a single excited receptor may amplify the signal by activating multiple G-proteins [9-11].. The chemotaxis signalling system can be described as the following Shannon communication channel [12,13]: the chemoattractant gradient direction as the input, the spatial distribution of occupied receptors as the intermediate step and the direction of cell ...
Upon starvation, Dictyostelium discoideum cells halt cell proliferation, aggregate into multicellular organisms, form migrating slugs, and undergo morphogenesis into fruiting bodies while differentiating into dormant spores and dead stalk cells. At almost any developmental stage cells can be forced to dedifferentiate when they are dispersed and diluted into nutrient broth. However, migrating slugs can traverse lawns of bacteria for days without dedifferentiating, ignoring abundant nutrients and continuing development. We now show that developing Dictyostelium cells revert to the growth phase only when bacteria are supplied during the first 4 to 6 h of development but that after this time, cells continue to develop regardless of the presence of food. We postulate that the cells inability to revert to the growth phase after 6 h represents a commitment to development. We show that the onset of commitment correlates with the cells loss of phagocytic function. By examining mutant strains, we also show that
Background: During infection by intracellular pathogens, a highly complex interplay occurs between the infected cell trying to degrade the invader and the pathogen which actively manipulates the host cell to enable survival and proliferation. Many intracellular pathogens pose important threats to human health and major efforts have been undertaken to better understand the host-pathogen interactions that eventually determine the outcome of the infection. Over the last decades, the unicellular eukaryote Dictyostelium discoideum has become an established infection model, serving as a surrogate macrophage that can be infected with a wide range of intracellular pathogens. In this study, we use high-throughput RNA-sequencing to analyze the transcriptional response of D. discoideum when infected with Mycobacterium marinum and Legionella pneumophila. The results were compared to available data from human macrophages.. Results: The majority of the transcriptional regulation triggered by the two pathogens ...
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Copines make up a multigene family of calcium-dependent, phospholipid-binding proteins. Copine proteins consists of two C2 domains at the N terminus followed by an "A domain" similar to the von Willebrand-Integrin A domain. Mutant studies of copines suggest that copines may be involved in signaling pathways and may play a significant role in cell differentiation, programmed cell death, and cell development. Copines need to be studied further to have a clear understanding of the function they play in organismal life processes. We are studying copine protein function in the model organism protozoan Dictyostelium discoideum. Previous research showed that the copine A (cpnA-) knockout strain of Dictyostelium exhibited normal growth rates, a slight cytokinesis defect, a developmental defect, and a defect in contractile vacuole function. Furthermore, real-time reverse transcription-PCR data suggested that all of the copine genes except cpnF may be important regulators of Dictyostelium development. To ...
Dictyostelium discoideum PIK1 protein: similar to phosphatidylinositide 3-kinases; regulate endosomal pathway; isolated from Dictyostelium discoideum; amino acid sequence in first source
Dictyostelium discoideum is a species of soil-living amoeba belonging to the phylum Amoebozoa, infraphylum Mycetozoa. Commonly referred to as slime mold, D. discoideum is a eukaryote that transitions from a collection of unicellular amoebae into a multicellular slug and then into a fruiting body within its lifetime. Its unique asexual lifecycle consists of four stages: vegetative, aggregation, migration, and culmination. The lifecycle of D. discoideum is relatively short, which allows for timely viewing of all stages. The cells involved in the lifecycle undergo movement, chemical signaling, and development, which are applicable to human cancer research. The simplicity of its lifecycle makes D. discoideum a valuable model organism to study genetic, cellular, and biochemical processes in other organisms. In the wild, D. discoideum can be found in soil and moist leaf litter. Its primary diet consists of bacteria, such as Escherichia coli, found in the soil and decaying organic matter. Uninucleate ...
The recognition step in the phagocytotic process of the unicellular amoeba dictyostelium discoideum was examined by analysis of mutants defective in phagocytosis, Reliable and simple assays were developed to measure endocytotic uptake. For pinocytosis, FITC-dextran was found to be a suitable fluid-phase marker; FITC-bacteria, latex beads, and erythrocytes were used as phagocytotic substrates. Ingested material was isolated in one step by centrifuging through highly viscous poly(ethyleneglycol) solutions and was analyzed optically.. A selection procedure for isolating mutants defective in phagocytosis was devised using tungsten beads as particulate prey. Nonphagocytosing cells were isolated on the basis of their lower density. Three mutant strains were found exhibiting a clear-cut phenotype directly related to the phagocytotic event.. In contrast to the situation in wild-type cells, uptake of E. coli B/r by mutant cells is specifically and competitively inhibited by glucose. Mutant amoeba ...
The gelation factor from Dictyostelium discoideum (ABP-120) is an actin binding protein consisting of six immunoglobulin (Ig) domains in the C-terminal rod domain. We have recently used the pair of domains 5 and 6 of ABP-120 as a model system for studying multi-domain nascent chain folding on the ribosome. Here we present the NMR assignments of domain 5 in its native and 8M urea-denatured states.. ...
During vertebrate development, mesodermal fate choices are regulated by interactions between morphogens such as activin/nodal, BMPs and Wnt/β-catenin that define anterior-posterior patterning and specify downstream derivatives including cardiomyocyte, endothelial and hematopoietic cells. We used human embryonic stem cells to explore how these pathways control mesodermal fate choices in vitro. Varying doses of activin A and BMP4 to mimic cytokine gradient polarization in the anterior-posterior axis of the embryo led to differential activity of Wnt/β-catenin signaling and specified distinct anterior-like (high activin/low BMP) and posterior-like (low activin/high BMP) mesodermal populations. Cardiogenic mesoderm was generated under conditions specifying anterior-like mesoderm, whereas blood-forming endothelium was generated from posterior-like mesoderm, and vessel-forming CD31+ endothelial cells were generated from all mesoderm origins. Surprisingly, inhibition of β-catenin signaling led to the ...
The degradation of Ins(1,3,4,5)P4 in Dictyostelium was investigated using a mixture of [3H]Ins(1,3,4,5)P4 and [3-32P]Ins-(1,3,4,5)P4. After incubation of this mixture with a Dictyostelium homogenate the 32P/3H ratio found in the InsP3 product was reduced to 24% of the ratio in the substrate. 32P-labelled inorganic phosphate was found as well, whereas hardly any InsP2 was detected. This indicates that Ins(1,3,4,5)P4 is mainly degraded by a 3-phosphatase. The other enzyme was characterized by identification of the 32P-labelled InsP3 isomer. This isomer did not co-elute with Ins(1,3,4)P3, indicating that no 5-phosphatase was present in Dictyostelium. The 32P-labelled InsP3 could be oxidized using NaIO4. The only InsP3 isomer that has these characteristics is Ins(3,4,5)P3, indicating 1-phosphatase activity. The 1-phosphatase appeared to be dependent on MgCl2, whereas the 3-phosphatase was still active in the absence of MgCl2. An analogue of Ins(1,3,4,5)P4 with a thiophosphate substitution at the ...
TY - JOUR. T1 - Mutants in the Dictyostelium Arp2/3 complex and chemoattractant-induced actin polymerization. AU - Langridge, Paul D.. AU - Kay, Robert R.. PY - 2007/7/15. Y1 - 2007/7/15. N2 - We have investigated the role of the Arp2/3 complex in Dictyostelium cell chemotaxis towards cyclic-AMP and in the actin polymerization that is triggered by this chemoattractant. We confirm that the Arp2/3 complex is recruited to the cell perimeter, or into a pseudopod, after cyclic-AMP stimulation and that this is coincident with actin polymerization. This recruitment is inhibited when actin polymerization is blocked using latrunculin suggesting that the complex binds to pre-existing actin filaments, rather than to a membrane associated signaling complex. We show genetically that an intact Arp2/3 complex is essential in Dictyostelium and have produced partially active mutants in two of its subunits. In these mutants both phases of actin polymerization in response to cyclic-AMP are greatly reduced. One ...
Chemotaxis, or directed cell migration, is important in many biological processes such as embryonic development, wound healing, and the direction of immune cells to sites of inflammation or infection. When not regulated properly, chemotaxis is implicated in disease states including inflammatory diseases and cancer metastasis. During eukaryotic chemotaxis, cells are able to sense a chemical gradient through receptors on the cell membrane that trigger complicated intracellular signaling networks, ultimately resulting in changes in the actin cytoskeleton leading to cell migration. The proteins involved in these signaling networks require tight spatiotemporal regulation, and the mechanisms underlying this regulation are not well understood. The work of this dissertation aims to better elucidate the pathways that regulate chemotaxis and enable cells to respond and adapt to changes in the chemoattractant gradient. To this end, we utilized the model organism Dictyostelium discoideum, and focused on ...
This work is concerned with some aspects of the social life of the amoebae |em|Dictyostelium discoideum|/em| (Dd). In particular, we shall focus on the early stages of the starvation-induced aggregation of Dd cells. Under such circumstances, amoebae are known to exchange a chemical messenger (cAMP) which acts as a signal to mediate their individual behaviour. This molecule is released from aggregation centres and advances through aggregation fields, first as circular waves and later on as spiral patterns. We shall recall below some of the basic features of this process, paying attention to the mathematical models that have been derived to account for experimental observations.
The social amoeba Dictyostelium discoideum senses the bacterial metabolite folic acid to track down bacteria. Previous studies suggested that the folic acid receptor is a serpentine receptor. In this study, I examined the transcriptional level changes of 46 putative serpentine receptor genes after folic acid stimulation. Seven candidate genes showed significantly up-regulated transcriptional levels, including fslA, fslB, fslH, fslJ, fslK, grlB, and grlD. Unfortunately, subsequent disruption of these genes did not affect folic acid sensing. Among these putative serpentine receptor gene mutants, grlB- cells exhibited delayed aggregation. Further studies suggest that GrlB is required for GABA binding. Detailed characterization of GABA metabolism indicates that GABA is used as an ancient signal during early development and culmination. Loss of GABA leads to a delay in early development and reduced detergent-resistant spores. GABA metabolism and signaling are regulated by distinct genes in different ...
So, since theres not a lot of information about the early multicellular stage and how it begins (the most relevant thing i could find being this thread from 3 years ago http://thrivegame.canadaboard.net/t1460-multicellu…
I recently wondered, in response to an ideas paper in BioEssays, whether animals, fungi, slime moulds etc. actually had a multicellular common ancestor. Dickinson and colleagues argument (partly) hinged on the shared presence of epithelia, barrier cell layers with distinct insides and outsides, in animals and the social amoeba Dictyostelium discoideum. The most recent crop…
The terminal structure of asexual development of Dictyostelium is comprised of a sorus (a spore mass) atop a stalk of vacuolated cells. Stalk-like cells also form the base of the organism and the `cups that surround the sorus. These terminally differentiated cells derive from non-committed prespore and prestalk precursors. The pioneering work of Williams, Kay, Firtel and others have shown that progenitors to both prestalk and prespore populations are heterogeneous (Gaudet et al., 2008; Williams, 2006; Yamada et al., 2010). Spatially restricted expression of gene patterns has been used to define very specific classes of prestalk cells (e.g. pstA, pstB, pstO and pstU cells). Here, we have focused on three main progenitor classes, prestalk A, prestalk B and prespore cells, but further subdivisions within each can be made (Gaudet et al., 2008; Kimmel, 2005; Kimmel and Firtel, 2004; Williams, 2006). We show that regulation of tyrosine phosphorylation of GSK3 in Dictyostelium underscores a paradigm ...
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Studies in Dictyostelium have shown that the p110-related phosphatidylinositol-3-kinases PI3K1 and PI3K2 are required for proper development, pinocytosis chemotaxis, and chemoattractant-mediated activation of PKB. Insights into the mechanism by which PI3K regulates chemotaxis derive from studies on PKB in mammalian leukocytes and Dictyostelium cells. PKB activation requires its translocation to the plasma membrane by binding of its PH domain to PtdIns(3,4,5)P3 and PtdIns(3,4)P2 produced upon activation of PI3K, leading to PKB activation. In leukocytes and Dictyostelium cells, chemoattractants mediate PKB activation through a G-protein-coupled pathway that requires the activity of the respective PI3Ks. Chemoattractant stimulation of neutrophils and Dictyostelium cells results in a transient localization of a GFP fusion of the PH domains from the Dictyostelium and mammalian PKBs to the plasma membrane. When these cells are placed in a chemoattractant gradient, membrane localization of the ...
Rice researchers find first to starve in slime mold thrive at others expense. Rice University evolutionary biologists reported in a paper published this week that the first cells to starve in a slime mold seem to have an advantage that not only helps them survive to reproduce, but also pushes those that keep on eating into sacrificing themselves for the common good.. The paper by Rice graduate student Jennie Kuzdzal-Fick and her mentors, David Queller and Joan Strassmann, Rices Harry C. and Olga K. Wiess Professors of Ecology and Evolutionary Biology, appears in the online edition of the Royal Society journal Biology Letters. The papers full title is "An Invitation to Die: Initiators of Sociality in a Social Amoeba Become Selfish Spores.". It helps to understand what Dictyostelium discoideum are, and how they behave. The single-cell organisms collectively known as slime mold live independently and feed on bacteria "" until the food runs out. When that happens, adjacent cells aggregate into a ...
TY - JOUR. T1 - Resetting wave forms in Dictyostelium territories. AU - Lee, Kyoung Jin. AU - Goldstein, R. E.. AU - Cox, E. C.. PY - 2001/8/6. Y1 - 2001/8/6. N2 - The mechanism of generation of spiral wave patterns in populations of Dictyostelium was probed experimentally by external chemical perturbation. Results supported the hypothesis that wave pattern selection occured by slow temporal variation of cell excitability. The processes were studied by resetting the waves with a spatially uniform pulse of extrinsic cyclic adeninemonophosphate (AMP).. AB - The mechanism of generation of spiral wave patterns in populations of Dictyostelium was probed experimentally by external chemical perturbation. Results supported the hypothesis that wave pattern selection occured by slow temporal variation of cell excitability. The processes were studied by resetting the waves with a spatially uniform pulse of extrinsic cyclic adeninemonophosphate (AMP).. UR - ...
A movie that shows phagosome acidification and neutralization visualized using FITC-yeast. Amoebae of Dictyostelium discoideum were fed living budding...
Fig. 3. Dictyostelium has PS-dependent γ-secretase activity that processes human APP to release Aβ peptides. (A) Diagrams of human APP α, β and γ proteolytic cleavage sites, and processed fragments; shown are FL (full-length), ΔN (N-terminal deletion), α- and β-CTFs, Aβ40 peptide, and AICD regions. (B) Media conditioned by growing WT and ps1-null cells that express ΔN-APP (a truncated human APP) were analyzed for levels of Aβ40 and Aβ42 peptides by quantitative ELISA. Fresh media and media conditioned by native WT cells were used as negative controls. Bars indicate standard errors that are derived from two independent experiments, each with two replicates. (C)Protein samples were collected from growing native WT Dictyostelium, or WT and ps1-null Dictyostelium that express ΔN-APP. ΔN-APP expression and processed fragments (arrows) were determined by immunoblot assay using α-APP C-terminus. (D) Protein samples were collected from native and APP-expressing CHO cells untreated or ...
Dictyostelium mutants lacking the MAP kinase DdERK2 show reduced chemotactic responses to folate and cAMP. Analysis of cAMP chemotaxis shows that Dderk2{dollar}\sp-{dollar} cells are defective in chemotaxis to high concentrations of cAMP. This defect is due to an inability to repolarize in the continued presence of high concentrations of cAMP. Under these conditions, the speed of movement of mutant cells remains low. Instead of generating a leading pseudopod, mutant cells generate transient crown-like structures over multiple regions of the cell surface. These structures differ from pseudopods in that they contain myosin II as well as F actin and coronin. These studies identify a role for MAP kinases in coordinating the formation of cell projections generated in response to chemoattractants. A polyclonal antibody against a MAP kinase (DdERK2) in Dictyostelium has been made and used to study DdERK2 activation and localization. The activation of DdERK2 by chemoattractants cAMP and folate is fast ...
Mono- and Stereopictres of 5.0 Angstrom coordination sphere of Magnesium atom in PDB 1mmn: X-Ray Structures Of The Mgadp, Mgatpgammas, and Mgamppnp Complexes of the Dictyostelium Discoideum Myosin Motor Domain
Dicty, as scientists call it, lives in soil as a single-cell creature for most of its life. If food becomes scarce, it has a unique survival strategy. It converges with other single-cell amoebas to create a multi-cellular organism that will mature and release spores for reproduction.. Dicty sits at the interface between single and multi-cellular organisms, says molecular biologist Rex Chisholm of Northwestern University in Chicago, Illinois. From an evolutionary point thats an interesting place to be.. Chisholm is spearheading a new public database for organizing genetic information about the organism. Chromosome two will contribute some of the first data included in Dictybase, whose design is based on other model organism databases like mouse and yeast.. With its 8.1 million base pairs, chromosome two represents about 25 percent of the Dictyostelium genome. Based on the surprisingly large number of genes in chromosome two, scientists predict the entire genome contains about 11,000 genes ...
Although bacteria release a wide diversity of volatile compounds that can diffuse in heterogeneous mixes of solids, liquids and gaseous milieu such as soil, organic tissues and microbial mats, little is known about their biological functions (Kai et al., 2009). Here we show that bacterial uptake and metabolism of biogenic ammonia increases the intracellular level of polyamines and influences antibiotic resistance and oxidative stress responses.. Ammonia production results from the metabolism of peptide and amino acid, the principal carbon sources in many environments, in which l-aspartate generally plays a central role in ammonia production as one of the most highly catabolysable amino acids in most bacteria (Reitzer, 2003; Sezonov et al., 2007; Alteri et al., 2009). Ammonia was previously shown to influence later stages of Dictyostelium discoideum development (Schaap et al., 1995) and to be involved in long-distance co-ordination of yeast growth leading to optimal distribution in their natural ...
Dictyostelium cells secrete the proteins AprA and CfaD. Cells lacking either AprA or CfaD proliferate faster than wild type, while AprA or CfaD overexpressor cells proliferate slowly, indicating that AprA and CfaD are autocrine factors that repress proliferation. CfaD interacts with AprA and requires the presence of AprA to slow proliferation. To determine if CfaD is necessary for the ability of AprA to slow proliferation, whether AprA binds to cells, and if so whether the binding requires the presence of CfaD, we examined the binding and effect on proliferation of recombinant AprA. We find that the extracellular accumulation of AprA increases with cell density and reaches a concentration of 0.3 μg/ml near a stationary cell density. When added to wild-type or aprA- cells, recombinant AprA (rAprA) significantly slows proliferation at 0.1 μg/ml and higher concentrations. From 4 to 64 μg/ml, the effect of rAprA is at a plateau, slowing but not stopping proliferation. The proliferation-inhibiting
1MNE: X-ray structure of the magnesium(II)-pyrophosphate complex of the truncated head of Dictyostelium discoideum myosin to 2.7 A resolution.
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. discoid …
Ily in the cell surface in Dictyostelium and is PKD2 and Mechanosensing in Dictyostelium a essential element in mechanosensing. This hypothesis is reinforced by
Sternfeld, John und David, Charles N. (1982): Fate and regulation of anterior-like cells in Dictyostelium slugs. In: Developmental Biology, Vol. 93, Nr. 1: S. 111-118 [PDF, 3MB] ...
Vibrio cholerae utilizes conserved virulence mechanisms to kill Dictyostelium: We can grow Dictyostelium cells in the laboratory by plating them with avirulent bacteria, like Klebsiella aerogenes. Amoebae ingest bacteria, which enables them to grow and form plaques. When Dictyostelium is plated with virulent Vibrio cholerae, amoebae are killed and unable to form plaques (middle plate). However, when we remove virulence genes from Vibrio, Dictyostelium cells can now utilize these bacteria as a source of nutrients, and form plaques (right plate). We can exploit this phenotypical difference and screen mutant libraries for virulence genes and their host targets.. Our biochemical and genetic data suggest that the type VI system injects effector molecules into the cytosol of infected host cells. We have identified one effector, VgrG1, which crosslinks cytoskeletal actin monomers to injure host cells - a process that requires direct contact. We are currently conducting experiments to define the ...
Opens the Highlight Feature Bar and highlights feature annotations from the FEATURES table of the record. The Highlight Feature Bar can be used to navigate to and highlight other features and provides links to display the highlighted region separately. Links in the FEATURES table will also highlight the corresponding region of the sequence. More... ...
The ampA gene is critical for Dictyostelium discoideum cell migration. To help understand the elusive ampA migrational pathway, second site suppressors were created by REMI mutagenesis. Three novel genes were identified as suppressors of the AmpA overexpressing increased migration phenotype. In order to understand and characterize the novel suppressor gene functions, mRFP fusion proteins were created and knockout cell lines were established. Isolation and characterization results of the three suppressors are described. REMI mutagenesis was used to identify second site suppressors of a primary mutation in AmpA overexpression. REMI involves the random insertion of a blasticidin resistance cassette into the genome and disruption of residing genes. Disruption of a gene participating in the ampA pathway will produce an alteration in phenotype. I screened for mutants which suppressed the large plaque phenotype in ampAOE cells; the plaque sizes are a reflection of their increased migration. Three ...
membrane, ATPase-coupled transmembrane transporter activity, culmination involved in sorocarp development, sorocarp morphogenesis, transmembrane transport
1. As a preliminary study on the molecular basis of cell aggregation, the soluble macromolecular fractions of growing (vegetative) and aggregation competent cells of D. discoideum were compared. a) ...
Monoclonal antibody against Cortexillin I expressed by ctxA for use in Function Blocking, Immunohistochemistry, Western Blot against Dictyostelium