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Sample records for dictyostelium discoideum differentiation-inducing

  1. Taxonomy Icon Data: Dictyostelium discoideum [Taxonomy Icon

    Lifescience Database Archive (English)

    Full Text Available Dictyostelium discoideum Dictyostelium discoideum Dictyostelium_discoideum_L.png Dictyostelium_disco...ideum_NL.png Dictyostelium_discoideum_S.png Dictyostelium_discoideum_NS.png http://biosciencedbc.jp/taxonomy_ico...n/icon.cgi?i=Dictyostelium+discoideum&t=L http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Dictyostelium+disco...ideum&t=NL http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Dictyostelium+disco...ideum&t=S http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Dictyostelium+discoideum&t=N

  2. Dictyostelium discoideum protocols

    Directory of Open Access Journals (Sweden)

    Carlo Alberto Redi

    2013-09-01

    Full Text Available As well highlighted and stressed by the two editors (Ludwig Eichinger, Center for Biochemistry, Medical Faculty, University of Cologne, Köln, Germany and Francisco Rivero, Center for Cardiovascular and Metabolic research, the Hull York Medical School, University of Hull, UK, Dictyostelium discoideum is an acclaimed member of the so-called model organisms....

  3. Cellulose biogenesis in Dictyostelium discoideum

    Energy Technology Data Exchange (ETDEWEB)

    Blanton, R.L.

    1993-12-31

    Organisms that synthesize cellulose can be found amongst the bacteria, protistans, fungi, and animals, but it is in plants that the importance of cellulose in function (as the major structural constituent of plant cell walls) and economic use (as wood and fiber) can be best appreciated. The structure of cellulose and its biosynthesis have been the subjects of intense investigation. One of the most important insights gained from these studies is that the synthesis of cellulose by living organisms involves much more than simply the polymerization of glucose into a (1{r_arrow}4)-{beta}-linked polymer. The number of glucoses in a polymer (the degree of polymerization), the crystalline form assumed by the glucan chains when they crystallize to form a microfibril, and the dimensions and orientation of the microfibrils are all subject to cellular control. Instead of cellulose biosynthesis, a more appropriate term might be cellulose biogenesis, to emphasize the involvement of cellular structures and mechanisms in controlling polymerization and directing crystallization and deposition. Dictyostelium discoideum is uniquely suitable for the study of cellulose biogenesis because of its amenability to experimental study and manipulation and the extent of our knowledge of its basic cellular mechanisms (as will be evident from the rest of this volume). In this chapter, I will summarize what is known about cellulose biogenesis in D. discoideum, emphasizing its potential to illuminate our understanding both of D. discoideum development and plant cellulose biogenesis.

  4. A phototaxis signalling complex in Dictyostelium discoideum.

    Science.gov (United States)

    Bandala-Sanchez, Esther; Annesley, Sarah J; Fisher, Paul R

    2006-09-01

    Phototaxis has been studied in a variety of organisms belonging to all three major taxonomic domains - the bacteria, the archaea and the eukarya. Dictyostelium discoideum is one of a small number of eukaryotic organisms which are amenable to studying the signalling pathways involved in phototaxis. In this study we provide evidence based on protein coimmunoprecipitation for a phototaxis signalling complex in Dictyostelium that includes the proteins RasD, filamin, ErkB, GRP125 and PKB.

  5. Thermotaxis by pseudoplasmodia of Dictyostelium discoideum

    Energy Technology Data Exchange (ETDEWEB)

    Poff, K.L.; Skokut, M.

    1977-05-01

    The temperature dependence of migration rate and of the thermotactic sensitivity of pseudoplasmodia of Dictyostelium discoideum has been measured. Migration rate increases with temperature to 20/sup 0/, is temperature insensitive from 20/sup 0/ to 27.5/sup 0/, and decreases with temperature to 29/sup 0/, above which point migration ceases. However, pseudoplasmodia formed from cells grown at 23.5/sup 0/ are thermotactic only from 22/sup 0/ to 27.5/sup 0/. Thus, a temperature dependence of migration rate is not sufficient to explain thermotaxis. Because random lateral movements by the pseudoplasmodia have not been observed, the measurement of the temperature gradient appears to be spatial rather than temporal, with a half-maximal thermotactic response to a temperature gradient of about 0.04/sup 0//cm, or 0.0004/sup 0/ across an average pseudoplasmodium. Thermotactic sensitivity is adaptive, with pseudoplasmodia formed from cells grown at 20/sup 0/ capable of thermotaxis at temperatures lower than cells grown at 23.5/sup 0/.

  6. Negative phototaxis of Dictyostelium discoideum pseudoplasmodia in UV radiation

    Energy Technology Data Exchange (ETDEWEB)

    Haeder, D.P. (Fachbereich Biologie-Botanik, Lahnberge, Marburg (Germany, F.R.))

    1985-02-01

    Pseudoplasmodia of the cellular slime mold Dictyostelium discoideum show negative phototactic orientation in lateral ultraviolet radiation. The action spectrum has a peak in the UV-B band near 280 nm. The absorption spectrum shows a prominent peak in the same wavelength range. Thus, negative phototaxis can be easily explained by the assumption that the lens effect, by which D. discoideum slugs detect the light direction, is defeated by the high internal absorption in this wavelength range.

  7. Sensory Adaptation of Dictyostelium discoideum Cells to Chemotactic Signals

    NARCIS (Netherlands)

    Haastert, Peter J.M. van

    1983-01-01

    Postvegetative Dictyostelium discoideum cells react chemotactically to gradients of cAMP, folic acid, and pterin. In the presence of a constant concentration of 10-5 M cAMP cells move at random. They still are able to respond to superimposed gradients of cAMP, although the response is less efficient

  8. The genome of the social amoeba Dictyostelium discoideum

    DEFF Research Database (Denmark)

    Eichinger, L; Pachebat, J A; Glöckner, G

    2005-01-01

    The social amoebae are exceptional in their ability to alternate between unicellular and multicellular forms. Here we describe the genome of the best-studied member of this group, Dictyostelium discoideum. The gene-dense chromosomes of this organism encode approximately 12,500 predicted proteins...

  9. DYNAMICS AND FUNCTION OF THE INOSITOLCYCLE IN DICTYOSTELIUM-DISCOIDEUM

    NARCIS (Netherlands)

    BOMINAAR, AA; VANDERKAAY, J; VANHAASTERT, PJM

    1991-01-01

    The inositolcycle in Dictyostelium discoideum was studied under several conditions both in vitro and in vivo. The results are compared with the inositolcycle as it is known from higher eukaryotes: although there is a strong resemblance both cycles are different at some essential points.

  10. Identification and phylogenetic analysis of Dictyostelium discoideum kinesin proteins

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    Glöckner Gernot

    2003-11-01

    Full Text Available Abstract Background Kinesins constitute a large superfamily of motor proteins in eukaryotic cells. They perform diverse tasks such as vesicle and organelle transport and chromosomal segregation in a microtubule- and ATP-dependent manner. In recent years, the genomes of a number of eukaryotic organisms have been completely sequenced. Subsequent studies revealed and classified the full set of members of the kinesin superfamily expressed by these organisms. For Dictyostelium discoideum, only five kinesin superfamily proteins (Kif's have already been reported. Results Here, we report the identification of thirteen kinesin genes exploiting the information from the raw shotgun reads of the Dictyostelium discoideum genome project. A phylogenetic tree of 390 kinesin motor domain sequences was built, grouping the Dictyostelium kinesins into nine subfamilies. According to known cellular functions or strong homologies to kinesins of other organisms, four of the Dictyostelium kinesins are involved in organelle transport, six are implicated in cell division processes, two are predicted to perform multiple functions, and one kinesin may be the founder of a new subclass. Conclusion This analysis of the Dictyostelium genome led to the identification of eight new kinesin motor proteins. According to an exhaustive phylogenetic comparison, Dictyostelium contains the same subset of kinesins that higher eukaryotes need to perform mitosis. Some of the kinesins are implicated in intracellular traffic and a small number have unpredictable functions.

  11. Dictyostelium discoideum: Molecular approaches to cell biology

    Energy Technology Data Exchange (ETDEWEB)

    Spudich, J.A.

    1987-01-01

    The central point of this book is to present Dictyostelium as a valuable eukaryotic organism for those interested in molecular studies that require a combined biochemical, structural, and genetic approach. The book is not meant to be a comprehensive compilation of all methods involving Dictyostelium, but instead is a selective set of chapters that demonstrates the utility of the organism for molecular approaches to interesting cell biological problems.

  12. Coupling of transcription and translation in Dictyostelium discoideum nuclei.

    Science.gov (United States)

    Mangiarotti, G

    1999-03-30

    The nuclei of Dictyostelium discoideum cells have been found to contain polyribosomes active in protein synthesis. mRNA molecules enter nuclear polyribosomes while they are still being synthesized. "Non sense mediated mRNA decay" occurs in the nucleus, through the interaction of the mRNAs containing a nonsense codon with newly formed nuclear ribosomes, rather than with cytoplasmic ribosomes, as previously generally supposed.

  13. Chemotaxis of Dictyostelium discoideum: collective oscillation of cellular contacts.

    Directory of Open Access Journals (Sweden)

    Edith Schäfer

    Full Text Available Chemotactic responses of Dictyostelium discoideum cells to periodic self-generated signals of extracellular cAMP comprise a large number of intricate morphological changes on different length scales. Here, we scrutinized chemotaxis of single Dictyostelium discoideum cells under conditions of starvation using a variety of optical, electrical and acoustic methods. Amebas were seeded on gold electrodes displaying impedance oscillations that were simultaneously analyzed by optical video microscopy to relate synchronous changes in cell density, morphology, and distance from the surface to the transient impedance signal. We found that starved amebas periodically reduce their overall distance from the surface producing a larger impedance and higher total fluorescence intensity in total internal reflection fluorescence microscopy. Therefore, we propose that the dominant sources of the observed impedance oscillations observed on electric cell-substrate impedance sensing electrodes are periodic changes of the overall cell-substrate distance of a cell. These synchronous changes of the cell-electrode distance were also observed in the oscillating signal of acoustic resonators covered with amebas. We also found that periodic cell-cell aggregation into transient clusters correlates with changes in the cell-substrate distance and might also contribute to the impedance signal. It turned out that cell-cell contacts as well as cell-substrate contacts form synchronously during chemotaxis of Dictyostelium discoideum cells.

  14. Secreted Cyclic Di-GMP Induces Stalk Cell Differentiation in the Eukaryote Dictyostelium discoideum.

    Science.gov (United States)

    Chen, Zhi-hui; Schaap, Pauline

    2016-01-01

    Cyclic di-GMP (c-di-GMP) is currently recognized as the most widely used intracellular signal molecule in prokaryotes, but roles in eukaryotes were only recently discovered. In the social amoeba Dictyostelium discoideum, c-di-GMP, produced by a prokaryote-type diguanylate cyclase, induces the differentiation of stalk cells, thereby enabling the formation of spore-bearing fruiting bodies. In this review, we summarize the currently known mechanisms that control the major life cycle transitions of Dictyostelium and focus particularly on the role of c-di-GMP in stalk formation. Stalk cell differentiation has characteristics of autophagic cell death, a process that also occurs in higher eukaryotes. We discuss the respective roles of c-di-GMP and of another signal molecule, differentiation-inducing factor 1, in autophagic cell death in vitro and in stalk formation in vivo.

  15. Chemotaxis to Excitable Waves in Dictyostelium Discoideum

    Science.gov (United States)

    Bhowmik, Arpan; Rappel, Wouter-Jan; Levine, Herbert

    In recent years, there have been significant advances in our understanding of the mechanisms underlying chemically directed motility by eukaryotic cells such as Dictyostelium. In particular, the LEGI model has proven capable of providing a framework for quantitatively explaining many experiments that present Dictyostelium cells with tailored chemical stimuli and monitor their subsequent polarization. Here, we couple the LEGI approach to an excitable medium model of the cAMP wave-field that is self-generated by the cells and investigate the extent to which this class of models enables accurate chemotaxis to the cAMP waveforms expected in vivo. Our results indicate that the ultra-sensitive version of the model does an excellent job in providing natural wave rectification, thereby providing a compelling solution to the ``back-of-the-wave paradox'' during cellular aggregation. This work was supported by National Institutes of Health Grant P01 GM078586.

  16. Steady-state models of glucose-perturbed Dictyostelium discoideum

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    Wright, B.E.; Reimers, J.M.

    1988-10-15

    Young sorocarps of Dictyostelium discoideum were incubated in the presence of 50 mM (/sup 14/C)glucose, and nine metabolites were isolated over a period of 60 min to determine their specific radioactivity. The program TFLUX was used to construct models consisting of 17 metabolite pools and 40 reactions (excluding external pools). Net glucose uptake was 10% or less in the two experiments chosen for extensive analysis, and a single steady-state model was adequate to describe the data in both cases. Despite differences in metabolite levels, flux, and labeling kinetics, the models of glucose-perturbed metabolism confirm earlier conclusions regarding metabolic compartments.

  17. Analysis of Dictyostelium discoideum Inositol Pyrophosphate Metabolism by Gel Electrophoresis

    Science.gov (United States)

    Pisani, Francesca; Livermore, Thomas; Rose, Giuseppina; Chubb, Jonathan Robert; Gaspari, Marco; Saiardi, Adolfo

    2014-01-01

    The social amoeba Dictyostelium discoideum was instrumental in the discovery and early characterization of inositol pyrophosphates, a class of molecules possessing highly-energetic pyrophosphate bonds. Inositol pyrophosphates regulate diverse biological processes and are attracting attention due to their ability to control energy metabolism and insulin signalling. However, inositol pyrophosphate research has been hampered by the lack of simple experimental procedures to study them. The recent development of polyacrylamide gel electrophoresis (PAGE) and simple staining to resolve and detect inositol pyrophosphate species has opened new investigative possibilities. This technology is now commonly applied to study in vitro enzymatic reactions. Here we employ PAGE technology to characterize the D. discoideum inositol pyrophosphate metabolism. Surprisingly, only three major bands are detectable after resolving acidic extract on PAGE. We have demonstrated that these three bands correspond to inositol hexakisphosphate (IP6 or Phytic acid) and its derivative inositol pyrophosphates, IP7 and IP8. Biochemical analyses and genetic evidence were used to establish the genuine inositol phosphate nature of these bands. We also identified IP9 in D. discoideum cells, a molecule so far detected only from in vitro biochemical reactions. Furthermore, we discovered that this amoeba possesses three different inositol pentakisphosphates (IP5) isomers, which are largely metabolised to inositol pyrophosphates. Comparison of PAGE with traditional Sax-HPLC revealed an underestimation of the cellular abundance of inositol pyrophosphates by traditional methods. In fact our study revealed much higher levels of inositol pyrophosphates in D. discoideum in the vegetative state than previously detected. A three-fold increase in IP8 was observed during development of D. discoideum a value lower that previously reported. Analysis of inositol pyrophosphate metabolism using ip6k null amoeba revealed

  18. Analysis of Dictyostelium discoideum inositol pyrophosphate metabolism by gel electrophoresis.

    Science.gov (United States)

    Pisani, Francesca; Livermore, Thomas; Rose, Giuseppina; Chubb, Jonathan Robert; Gaspari, Marco; Saiardi, Adolfo

    2014-01-01

    The social amoeba Dictyostelium discoideum was instrumental in the discovery and early characterization of inositol pyrophosphates, a class of molecules possessing highly-energetic pyrophosphate bonds. Inositol pyrophosphates regulate diverse biological processes and are attracting attention due to their ability to control energy metabolism and insulin signalling. However, inositol pyrophosphate research has been hampered by the lack of simple experimental procedures to study them. The recent development of polyacrylamide gel electrophoresis (PAGE) and simple staining to resolve and detect inositol pyrophosphate species has opened new investigative possibilities. This technology is now commonly applied to study in vitro enzymatic reactions. Here we employ PAGE technology to characterize the D. discoideum inositol pyrophosphate metabolism. Surprisingly, only three major bands are detectable after resolving acidic extract on PAGE. We have demonstrated that these three bands correspond to inositol hexakisphosphate (IP₆ or Phytic acid) and its derivative inositol pyrophosphates, IP₇ and IP₈. Biochemical analyses and genetic evidence were used to establish the genuine inositol phosphate nature of these bands. We also identified IP₉ in D. discoideum cells, a molecule so far detected only from in vitro biochemical reactions. Furthermore, we discovered that this amoeba possesses three different inositol pentakisphosphates (IP₅) isomers, which are largely metabolised to inositol pyrophosphates. Comparison of PAGE with traditional Sax-HPLC revealed an underestimation of the cellular abundance of inositol pyrophosphates by traditional methods. In fact our study revealed much higher levels of inositol pyrophosphates in D. discoideum in the vegetative state than previously detected. A three-fold increase in IP₈ was observed during development of D. discoideum a value lower that previously reported. Analysis of inositol pyrophosphate metabolism using ip6k null amoeba

  19. Analysis of Dictyostelium discoideum inositol pyrophosphate metabolism by gel electrophoresis.

    Directory of Open Access Journals (Sweden)

    Francesca Pisani

    Full Text Available The social amoeba Dictyostelium discoideum was instrumental in the discovery and early characterization of inositol pyrophosphates, a class of molecules possessing highly-energetic pyrophosphate bonds. Inositol pyrophosphates regulate diverse biological processes and are attracting attention due to their ability to control energy metabolism and insulin signalling. However, inositol pyrophosphate research has been hampered by the lack of simple experimental procedures to study them. The recent development of polyacrylamide gel electrophoresis (PAGE and simple staining to resolve and detect inositol pyrophosphate species has opened new investigative possibilities. This technology is now commonly applied to study in vitro enzymatic reactions. Here we employ PAGE technology to characterize the D. discoideum inositol pyrophosphate metabolism. Surprisingly, only three major bands are detectable after resolving acidic extract on PAGE. We have demonstrated that these three bands correspond to inositol hexakisphosphate (IP₆ or Phytic acid and its derivative inositol pyrophosphates, IP₇ and IP₈. Biochemical analyses and genetic evidence were used to establish the genuine inositol phosphate nature of these bands. We also identified IP₉ in D. discoideum cells, a molecule so far detected only from in vitro biochemical reactions. Furthermore, we discovered that this amoeba possesses three different inositol pentakisphosphates (IP₅ isomers, which are largely metabolised to inositol pyrophosphates. Comparison of PAGE with traditional Sax-HPLC revealed an underestimation of the cellular abundance of inositol pyrophosphates by traditional methods. In fact our study revealed much higher levels of inositol pyrophosphates in D. discoideum in the vegetative state than previously detected. A three-fold increase in IP₈ was observed during development of D. discoideum a value lower that previously reported. Analysis of inositol pyrophosphate metabolism using

  20. Classification and expression analyses of homeobox genes from Dictyostelium discoideum

    Indian Academy of Sciences (India)

    Himanshu Mishra; Shweta Saran

    2015-06-01

    Homeobox genes are compared between genomes in an attempt to understand the evolution of animal development. The ability of the protist, Dictyostelium discoideum, to shift between uni- and multicellularity makes this group ideal for studying the genetic changes that may have occurred during this transition. We present here the first genome-wide classification and comparative genomic analysis of the 14 homeobox genes present in D. discoideum. Based on the structural alignment of the homeodomains, they can be broadly divided into TALE and non-TALE classes. When individual homeobox genes were compared with members of known class or family, we could further classify them into 3 groups, namely, TALE, OTHER and NOVEL classes, but no HOX family was found. The 5 members of TALE class could be further divided into PBX, PKNOX, IRX and CUP families; 4 homeobox genes classified as NOVEL did not show any similarity to any known homeobox genes; while the remaining 5 were classified as OTHERS as they did show certain degree of similarity to few known homeobox genes. No unique RNA expression pattern during development of D. discoideum emerged for members of an individual group. Putative promoter analysis revealed binding sites for few homeobox transcription factors among many probable factors.

  1. Evidence for a Messenger Function of Cyclic GMP During Phosphodiesterase Induction in Dictyostelium discoideum

    NARCIS (Netherlands)

    Haastert, Peter J.M. van; Pasveer, Frank J.; Meer, Rob C. van der; Heijden, Paul R. van der; Walsum, Hans van; Konijn, Theo M.

    1982-01-01

    Chemotactic stimulation of vegetative or aggregative Dictyostelium discoideum cells induced a transient elevation of cyclic GMP levels. The addition of chemoattractants to postvegetative cells by pulsing induced phosphodiesterase activity. The following lines of evidence suggest a messenger function

  2. Crystallization of cyclase-associated protein from Dictyostelium discoideum.

    Science.gov (United States)

    Hofmann, Andreas; Hess, Sonja; Noegel, Angelika A; Schleicher, Michael; Wlodawer, Alexander

    2002-10-01

    Cyclase-associated protein (CAP) is a conserved two-domain protein that helps to activate the catalytic activity of adenylyl cyclase in the cyclase-bound state through interaction with Ras, which binds to the cyclase in a different region. With its other domain, CAP can bind monomeric actin and therefore also carries a cytoskeletal function. The protein is thus involved in Ras/cAMP-dependent signal transduction and most likely serves as an adapter protein translocating the adenylyl cyclase complex to the actin cytoskeleton. Crystals belonging to the orthorhombic space group C222, with unit-cell parameters a = 71.2, b = 75.1, c = 162.9 A, have been obtained from Dictyostelium discoideum CAP carrying a C-terminal His tag. A complete native data set extending to 2.2 A resolution was collected from a single crystal using an in-house X-ray system. The asymmetric unit contains one molecule of CAP.

  3. Secondary Ion Mass Spectrometry Imaging of Dictyostelium discoideum Aggregation Streams

    Energy Technology Data Exchange (ETDEWEB)

    Debord, J. Daniel; Smith, Donald F.; Anderton, Christopher R.; Heeren, Ronald M.; Pasa-Tolic, Ljiljana; Gomer, Richard H.; Fernandez-Lima, Francisco A.

    2014-06-09

    High resolution imaging mass spectrometry could become a valuable tool for cell and developmental biology, but both, high spatial and mass spectral resolution are needed to enable this. In this report, we employed Bi3 bombardment time-of-flight (Bi3 ToF-SIMS) and C60 bombardment Fourier transform ion cyclotron resonance secondary ion mass spectrometry (C60 FTICR-SIMS) to image Dictyostelium discoideum aggregation streams. Nearly 300 lipid species were identified from the aggregation streams. High resolution mass spectrometry imaging (FTICR-SIMS) enabled the generation of multiple molecular ion maps at the nominal mass level and provided good coverage for fatty acyls, prenol lipids, and sterol lipids. The comparison of Bi3 ToF-SIMS and C60 FTICR-SIMS suggested that while the first provides fast, high spatial resolution molecular ion images, the chemical complexity of biological samples warrants the use of high resolution analyzers for accurate ion identification.

  4. Sketch the migration of Dictyostelium discoideum using phase field model

    Science.gov (United States)

    Zhang, Yunsong; Camley, Brian; Rappel, Wouter-Jan; Levine, Herbert

    Cell migration plays an important role in a lot of biological processes, like chemotaxis, wound healing, and cancer metastasis. The fact it is highly integrated has brought great challenges, physical and mathematical, to the modeling efforts. Recently, a phase field model, which couples cellular reaction dynamics, intra-cellular hydrodynamics, cell-substrate adhesions and deformable cell boundaries, has successfully captured some characteristics of moving cells, including morphological change, cytosolic actin flow pattern, periodic migration and so on. Here we apply the phase field model to sketch the migration of Dictyostelium discoideum, which shows a completely different moving pattern from the cells (like fish keratocyte) in our previous attempts. And we will also compare our results with some experimental observations, not only on the cell morphology, but also on the traction force patterns on the substrate.

  5. Identification and characterization of peptide: N- glycanase from Dictyostelium discoideum

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    Gosain Anuradha

    2012-06-01

    Full Text Available Abstract Background Peptide: N- glycanase (PNGase enzyme cleaves oligosaccharides from the misfolded glycoproteins and prepares them for degradation. This enzyme plays a role in the endoplasmic reticulum associated degradation (ERAD pathway in yeast and mice but its biological importance and role in multicellular development remain largely unknown. Results In this study, the PNGase from the cellular slime mold, Dictyostelium discoideum (DdPNGase was identified based on the presence of a common TG (transglutaminase core domain and its sequence homology with the known PNGases. The domain architecture and the sequence comparison validated the presence of probable functional domains in DdPNGase. The tertiary structure matched with the mouse PNGase. Here we show that DdPNGase is an essential protein, required for aggregation during multicellular development and a knockout strain of it results in small sized aggregates, all of which did not form fruiting bodies. The in situ hybridization and RT-PCR results show higher level of expression during the aggregate stage. The expression gets restricted to the prestalk region during later developmental stages. DdPNGase is a functional peptide:N-glycanase enzyme possessing deglycosylation activity, but does not possess any significant transamidation activity. Conclusions We have identified and characterized a novel PNGase from D. discoideum and confirmed its deglycosylation activity. The results emphasize the importance of PNGase in aggregation during multicellular development of this organism.

  6. Multi-scale interactions in Dictyostelium discoideum aggregation

    Science.gov (United States)

    Dixon, James A.; Kelty-Stephen, Damian G.

    2012-12-01

    Cellular aggregation is essential for a wide range of phenomena in developmental biology, and a crucial event in the life-cycle of Dictyostelium discoideum. The current manuscript presents an analysis of multi-scale interactions involved in D. discoideum aggregation and non-aggregation events. The multi-scale fractal dimensions of a sequence of microscope images were used to estimate changing structure at different spatial scales. Three regions showing aggregation and three showing non-aggregation were considered. The results showed that both aggregation and non-aggregation regions were strongly multi-fractal. Analyses of the over-time relationships among nine scales of the generalized dimension, D(q), were conducted using vector autoregression and vector error-correction models. Both types of regions showed evidence that across-scale interactions serve to maintain the equilibrium of the system. Aggregation and non-aggregation regions also showed different patterns of effects of individual scales on other scales. Specifically, aggregation regions showed greater effects of both the smallest and largest scales on the smaller scale structures. The results suggest that multi-scale interactions are responsible for maintaining and altering the cellular structures during aggregation.

  7. Arachidonic acid is a chemoattractant for Dictyostelium discoideum cells

    Indian Academy of Sciences (India)

    Ralph H Schaloske; Dagmar Blaesius; Christina Schlatterer; Daniel F Lusche

    2007-12-01

    Cyclic AMP (cAMP) is a natural chemoattractant of the social amoeba Dictyostelium discoideum. It is detected by cell surface cAMP receptors. Besides a signalling cascade involving phosphatidylinositol 3,4,5-trisphosphate (PIP3), Ca2+ signalling has been shown to have a major role in chemotaxis. Previously, we have shown that arachidonic acid (AA) induces an increase in the cytosolic Ca2+ concentration by causing the release of Ca2+ from intracellular stores and activating influx of extracellular Ca2+. Here we report that AA is a chemoattractant for D. discoideum cells differentiated for 8–9 h. Motility towards a glass capillary filled with an AA solution was dose-dependent and qualitatively comparable to cAMP-induced chemotaxis. Ca2+ played an important role in AA chemotaxis of wild-type Ax2 as ethyleneglycolbis(b-aminoethyl)-N,N,N′,N′-tetraacetic acid (EGTA) added to the extracellular buffer strongly inhibited motility. In the HM1049 mutant whose iplA gene encoding a putative Ins(1,4,5)P3-receptor had been knocked out, chemotaxis was only slightly affected by EGTA. Chemotaxis in the presence of extracellular Ca2+ was similar in both strains. Unlike cAMP, addition of AA to a cell suspension did not change cAMP or cGMP levels. A model for AA chemotaxis based on the findings in this and previous work is presented.

  8. A new social gene in Dictyostelium discoideum, chtB

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    Santorelli Lorenzo A

    2013-01-01

    Full Text Available Abstract Background Competitive social interactions are ubiquitous in nature, but their genetic basis is difficult to determine. Much can be learned from single gene knockouts in a eukaryote microbe. The mutants can be competed with the parent to discern the social impact of that specific gene. Dictyostelium discoideum is a social amoeba that exhibits cooperative behavior in the construction of a multicellular fruiting body. It is a good model organism to study the genetic basis of cooperation since it has a sequenced genome and it is amenable to genetic manipulation. When two strains of D. discoideum are mixed, a cheater strain can exploit its social partner by differentiating more spore than its fair share relative to stalk cells. Cheater strains can be generated in the lab or found in the wild and genetic analyses have shown that cheating behavior can be achieved through many pathways. Results We have characterized the knockout mutant chtB, which was isolated from a screen for cheater mutants that were also able to form normal fruiting bodies on their own. When mixed in equal proportions with parental strain cells, chtB mutants contributed almost 60% of the total number of spores. To do so, chtB cells inhibit wild type cells from becoming spores, as indicated by counts and by the wild type cells’ reduced expression of the prespore gene, cotB. We found no obvious fitness costs (morphology, doubling time in liquid medium, spore production, and germination efficiency associated with the cheating ability of the chtB knockout. Conclusions In this study we describe a new gene in D. discoideum, chtB, which when knocked out inhibits the parental strain from producing spores. Moreover, under lab conditions, we did not detect any fitness costs associated with this behavior.

  9. The Long Noncoding RNA Transcriptome of Dictyostelium discoideum Development

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    Rafael D. Rosengarten

    2017-02-01

    Full Text Available Dictyostelium discoideum live in the soil as single cells, engulfing bacteria and growing vegetatively. Upon starvation, tens of thousands of amoebae enter a developmental program that includes aggregation, multicellular differentiation, and sporulation. Major shifts across the protein-coding transcriptome accompany these developmental changes. However, no study has presented a global survey of long noncoding RNAs (ncRNAs in D. discoideum. To characterize the antisense and long intergenic noncoding RNA (lncRNA transcriptome, we analyzed previously published developmental time course samples using an RNA-sequencing (RNA-seq library preparation method that selectively depletes ribosomal RNAs (rRNAs. We detected the accumulation of transcripts for 9833 protein-coding messenger RNAs (mRNAs, 621 lncRNAs, and 162 putative antisense RNAs (asRNAs. The noncoding RNAs were interspersed throughout the genome, and were distinct in expression level, length, and nucleotide composition. The noncoding transcriptome displayed a temporal profile similar to the coding transcriptome, with stages of gradual change interspersed with larger leaps. The transcription profiles of some noncoding RNAs were strongly correlated with known differentially expressed coding RNAs, hinting at a functional role for these molecules during development. Examining the mitochondrial transcriptome, we modeled two novel antisense transcripts. We applied yet another ribosomal depletion method to a subset of the samples to better retain transfer RNA (tRNA transcripts. We observed polymorphisms in tRNA anticodons that suggested a post-transcriptional means by which D. discoideum compensates for codons missing in the genomic complement of tRNAs. We concluded that the prevalence and characteristics of long ncRNAs indicate that these molecules are relevant to the progression of molecular and cellular phenotypes during development.

  10. Cheating by exploitation of developmental prestalk patterning in Dictyostelium discoideum.

    Directory of Open Access Journals (Sweden)

    Anupama Khare

    2010-02-01

    Full Text Available The cooperative developmental system of the social amoeba Dictyostelium discoideum is susceptible to exploitation by cheaters-strains that make more than their fair share of spores in chimerae. Laboratory screens in Dictyostelium have shown that the genetic potential for facultative cheating is high, and field surveys have shown that cheaters are abundant in nature, but the cheating mechanisms are largely unknown. Here we describe cheater C (chtC, a strong facultative cheater mutant that cheats by affecting prestalk differentiation. The chtC gene is developmentally regulated and its mRNA becomes stalk-enriched at the end of development. chtC mutants are defective in maintaining the prestalk cell fate as some of their prestalk cells transdifferentiate into prespore cells, but that defect does not affect gross developmental morphology or sporulation efficiency. In chimerae between wild-type and chtC mutant cells, the wild-type cells preferentially give rise to prestalk cells, and the chtC mutants increase their representation in the spore mass. Mixing chtC mutants with other cell-type proportioning mutants revealed that the cheating is directly related to the prestalk-differentiation propensity of the victim. These findings illustrate that a cheater can victimize cooperative strains by exploiting an established developmental pathway.

  11. Dictyostelium discoideum salvages purine deoxyribonucleosides by highly specific bacterial-like deoxyribonucleoside kinases

    DEFF Research Database (Denmark)

    Sandrini, Michael; Soderbom, F.; Mikkelsen, N.E.;

    2007-01-01

    The salvage of deoxyribonucleosides in the social amoeba Dictyostelium discoideum, which has an extremely A + T-rich genome, was investigated. All native deoxyribonucleosides were phosphorylated by D. discoideum cell extracts and we subcloned three deoxyribonucleoside kinase (dNK) encoding genes....

  12. Subcellular localization of ammonium transporters in Dictyostelium discoideum

    Directory of Open Access Journals (Sweden)

    Davis Carter T

    2008-12-01

    Full Text Available Abstract Background With the exception of vertebrates, most organisms have plasma membrane associated ammonium transporters which primarily serve to import a source of nitrogen for nutritional purposes. Dictyostelium discoideum has three ammonium transporters, Amts A, B and C. Our present work used fluorescent fusion proteins to determine the cellular localization of the Amts and tested the hypothesis that the transporters mediate removal of ammonia generated endogenously from the elevated protein catabolism common to many protists. Results Using RFP and YFP fusion constructs driven by the actin 15 promoter, we found that the three ammonium transporters were localized on the plasma membrane and on the membranes of subcellular organelles. AmtA and AmtB were localized on the membranes of endolysosomes and phagosomes, with AmtB further localized on the membranes of contractile vacuoles. AmtC also was localized on subcellular organelles when it was stabilized by coexpression with either the AmtA or AmtB fusion transporter. The three ammonium transporters exported ammonia linearly with regard to time during the first 18 hours of the developmental program as revealed by reduced export in the null strains. The fluorescently tagged transporters rescued export when expressed in the null strains, and thus they were functional transporters. Conclusion Unlike ammonium transporters in most organisms, which import NH3/NH4+ as a nitrogen source, those of Dictyostelium export ammonia/ammonium as a waste product from extensive catabolism of exogenously derived and endogenous proteins. Localization on proteolytic organelles and on the neutral contractile vacuole suggests that Dictyostelium ammonium transporters may have unique subcellular functions and play a role in the maintenance of intracellular ammonium distribution. A lack of correlation between the null strain phenotypes and ammonia excretion properties of the ammonium transporters suggests that it is not

  13. Cell substratum adhesion during early development of Dictyostelium discoideum.

    Directory of Open Access Journals (Sweden)

    Marco Tarantola

    Full Text Available Vegetative and developed amoebae of Dictyostelium discoideum gain traction and move rapidly on a wide range of substrata without forming focal adhesions. We used two independent assays to quantify cell-substrate adhesion in mutants and in wild-type cells as a function of development. Using a microfluidic device that generates a range of hydrodynamic shear stress, we found that substratum adhesion decreases at least 10 fold during the first 6 hr of development of wild type cells. This result was confirmed using a single-cell assay in which cells were attached to the cantilever of an atomic force probe and allowed to adhere to untreated glass surfaces before being retracted. Both of these assays showed that the decrease in substratum adhesion was dependent on the cAMP receptor CAR1 which triggers development. Vegetative cells missing talin as the result of a mutation in talA exhibited slightly reduced adhesive properties compared to vegetative wild-type cells. In sharp contrast to wild-type cells, however, these talA mutant cells did not show further reduction of adhesion during development such that after 5 hr of development they were significantly more adhesive than developed wild type cells. In addition, both assays showed that substrate adhesion was reduced in 0 hr cells when the actin cytoskeleton was disrupted by latrunculin. Consistent with previous observations, substrate adhesion was also reduced in 0 hr cells lacking the membrane proteins SadA or SibA as the result of mutations in sadA or sibA. However, there was no difference in the adhesion properties between wild type AX3 cells and these mutant cells after 6 hr of development, suggesting that neither SibA nor SadA play an essential role in substratum adhesion during aggregation. Our results provide a quantitative framework for further studies of cell substratum adhesion in Dictyostelium.

  14. A Continuum Model of Actin Waves in Dictyostelium discoideum

    Science.gov (United States)

    Khamviwath, Varunyu; Hu, Jifeng; Othmer, Hans G.

    2013-01-01

    Actin waves are complex dynamical patterns of the dendritic network of filamentous actin in eukaryotes. We developed a model of actin waves in PTEN-deficient Dictyostelium discoideum by deriving an approximation of the dynamics of discrete actin filaments and combining it with a signaling pathway that controls filament branching. This signaling pathway, together with the actin network, contains a positive feedback loop that drives the actin waves. Our model predicts the structure, composition, and dynamics of waves that are consistent with existing experimental evidence, as well as the biochemical dependence on various protein partners. Simulation suggests that actin waves are initiated when local actin network activity, caused by an independent process, exceeds a certain threshold. Moreover, diffusion of proteins that form a positive feedback loop with the actin network alone is sufficient for propagation of actin waves at the observed speed of . Decay of the wave back can be caused by scarcity of network components, and the shape of actin waves is highly dependent on the filament disassembly rate. The model allows retraction of actin waves and captures formation of new wave fronts in broken waves. Our results demonstrate that a delicate balance between a positive feedback, filament disassembly, and local availability of network components is essential for the complex dynamics of actin waves. PMID:23741312

  15. Identification and recombinant expression of anandamide hydrolyzing enzyme from Dictyostelium discoideum

    Directory of Open Access Journals (Sweden)

    Neelamegan Dhamodharan

    2012-06-01

    Full Text Available Abstract Background Anandamide (Arachidonoyl ethanolamide is a potent bioactive lipid studied extensively in humans, which regulates several neurobehavioral processes including pain, feeding and memory. Bioactivity is terminated when hydrolyzed into free arachidonic acid and ethanolamine by the enzyme fatty acid amide hydrolase (FAAH. In this study we report the identification of a FAAH homolog from Dictyostelium discoideum and its function to hydrolyze anandamide. Results A putative FAAH DNA sequence coding for a conserved amidase signature motif was identified in the Dictyostelium genome database and the corresponding cDNA was isolated and expressed as an epitope tagged fusion protein in either E.coli or Dictyostelium. Wild type Dictyostelium cells express FAAH throughout their development life cycle and the protein was found to be predominantly membrane associated. Production of recombinant HIS tagged FAAH protein was not supported in E.coli host, but homologous Dictyostelium host was able to produce the same successfully. Recombinant FAAH protein isolated from Dictyostelium was shown to hydrolyze anandamide and related synthetic fatty acid amide substrates. Conclusions This study describes the first identification and characterisation of an anandamide hydrolyzing enzyme from Dictyostelium discoideum, suggesting the potential of Dictyostelium as a simple eukaryotic model system for studying mechanisms of action of any FAAH inhibitors as drug targets.

  16. Chemotaxis to cyclic AMP and folic acid is mediated by different G proteins in Dictyostelium discoideum

    NARCIS (Netherlands)

    Kesbeke, Fanja; Haastert, Peter J.M. van; Wit, René J.W. de; Snaar-Jagalska, B. Ewa

    1990-01-01

    Mutant Frigid A (fgdA) of Dictyostelium discoideum is defective in a functional Gα2 subunit of a G protein and is characterized by a complete blockade of the cyclic AMP-mediated sensory transduction steps, including cyclic AMP relay, chemotaxis and the cyclic GMP response. Folic acid-mediated transm

  17. Transmethylation inhibitors decrease chemotactic sensitivity and delay cell aggregation in Dictyostelium discoideum

    NARCIS (Netherlands)

    van Waarde, A; van Haastert, P J

    1984-01-01

    In Dictyostelium discoideum, extracellular cyclic AMP (cAMP) induces chemotaxis and cell aggregation. Suspensions of cAMP-sensitive cells respond to a cAMP pulse with a rapid, transient increase of protein carboxyl methylation. The transmethylation inhibitors cycloleucine, L-homocysteine thiolactone

  18. Normal chemotaxis in Dictyostelium discoideum cells with a depolarized plasma membrane potential

    NARCIS (Netherlands)

    Duijn, Bert van; Vogelzang, Sake A.; Ypey, Dirk L.; Molen, Loek G. van der; Haastert, Peter J.M. van

    1990-01-01

    We examined a possible role for the plasma membrane potential in signal transduction during cyclic AMP-induced chemotaxis in the cellular slime mold Dictyostelium discoideum. Chemotaxis, cyclic GMP and cyclic AMP responses in cells with a depolarized membrane potential were measured. Cells can be

  19. Developmental regulation of the Inositol 1,4,5-trisphosphate phosphatases in Dictyostelium discoideum

    NARCIS (Netherlands)

    Bominaar, Anthony A.; Dijken, Peter van; Draijer, Richard; Haastert, Peter J.M. van

    1991-01-01

    The cellular slime mold Dictyostelium discoideum is a microorganism in which growth and development are strictly separated. Starvation initiates a developmental program in which extracellular cAMP plays a major role as a signal molecule. In response to cAMP several second messengers are produced, in

  20. Random mutagenesis and screening of complex glycoproteins : expression of human gonadotropins in Dictyostelium discoideum

    NARCIS (Netherlands)

    Linskens, Maarten H.K.; Grootenhuis, Peter D.J.; Blaauw, Mieke; Huisman-de Winkel, Bianca; Ravestein, Arno van; Haastert, Peter J.M. van; Heikoop, Judith C.

    1999-01-01

    The soil amoeba Dictyostelium discoideum is a host cell that provides simple genetics in combination with complex protein synthesis. We show that the complex human heterodimeric gonadotropins can be produced and secreted by this organism, Furthermore, both follicle stimulation hormone and choriogona

  1. Dictyostelium discoideum contains three inositol monophosphatase activities with different substrate specificities and sensitivities to lithium

    NARCIS (Netherlands)

    Dijken, Peter van; Bergsma, Jan C.T.; Hiemstra, Hoebert S.; Vries, Berber de; Kaay, Jeroen van der; Haastert, Peter J.M. van

    1996-01-01

    The small ion lithium, a very effective agent in the treatment of manic depressive patients, inhibits the mammalian enzyme inositol monophosphatase, which is proposed as the biological target for the effects of lithium. In this study we investigated Dictyostelium discoideum inositol monophosphatase

  2. Pertussis toxin inhibits cAMP-induced desensitization of adenylate cyclase in Dictyostelium discoideum

    NARCIS (Netherlands)

    Snaar-Jagalska, B. Ewa; Haastert, Peter J.M. van

    1990-01-01

    cAMP binds to surface receptors of Dictyostelium discoideum cells, transducing the signal to adenylate cyclase, guanylate cyclase and to chemotaxis. The activation of adenylate cyclase is maximal after 1 min and then declines to basal levels due to desensitization, which is composed of two component

  3. Regulation of TORC2 complex in Dictyostelium discoideum

    NARCIS (Netherlands)

    Khanna, Ankita

    2016-01-01

    Dictyostelium is an amoeba that lives in the soil where it feeds on bacteria. During scarcity of food, Dictyostelium cells undergo a highly regulated developmental process in which the cells aggregate by chemotaxing towards pulsatile emission of extracellular cAMP from a signaling center; the cells

  4. Stimulation of mitotic recombination in Dictyostelium discoideum by ultraviolet irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, J.S.; Newell, P.C. (Oxford Univ. (UK). Dept. of Biochemistry)

    1982-01-01

    Studies were carried out to find an agent that would induce mitotic recombination in D. discoideum. The results indicate that most of the known chemical recombinogens have no effect on the mitotic recombination frequency in D. discoideum but that UV irradiation can significantly increase it by up to 100-fold at doses that have only a small effect on the haploidisation and mutation rates under the conditions employed.

  5. Dictyostelium discoideum as a novel host system to study the interaction between phagocytes and yeasts

    Directory of Open Access Journals (Sweden)

    Barbara Koller

    2016-10-01

    Full Text Available 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 plate test for screening purposes after random mutagenesis. Finally, we discuss the potential of our adapted amoebae plate test to use D. discoideum for risk assessment of yeast strains.

  6. DNA damage and its repair in Dictyostelium discoideum irradiated by health lamp light (UV-B)

    Energy Technology Data Exchange (ETDEWEB)

    Okaichi, K.; Kajitani, N.; Nakajima, K.; Nozu, K.; Ohnishi, T. (Nara Medical Univ., Kashihara (Japan))

    1989-07-01

    Irradiation by health lamp (HL) light (280-320 nm) more efficiently induced cell killing and mutation in a radiation sensitive mutant (TW8) of Dictyostelium discoideum as compared with the parental wild-type strain (NC4). This light as well as a germicidal lamp-light (254 nm) produced pyrimidine dimers. The dimers were removed from DNA molecules by excision repair in NC4, but more slowly in TW8. It is suggested that pyrimidine dimers are the main DNA damage caused by HL light in D. discoideum, and that this results in cell killing and induced mutation. (author).

  7. Studies on the transcription, translation, and structure of alpha- actinin in Dictyostelium discoideum

    OpenAIRE

    1986-01-01

    A clone coding for the F-actin cross-linking protein alpha-actinin was obtained by screening a genomic library of Dictyostelium discoideum DNA in lambda gt11 with monoclonal antibodies specific for Dictyostelium alpha-actinin. The 1.2-kilobase (kb) genomic clone was confirmed as containing part of the alpha-actinin gene by comparing its nucleotide sequence with the amino acid sequence of tryptic peptides from purified alpha-actinin. The clone recognized a 3.0-kb message in a Northern blot. Hy...

  8. Two dephosphorylation pathways of inositol 1,4,5-trisphosphate in homogenates of the cellular slime mould Dictyostelium discoideum

    NARCIS (Netherlands)

    Lookeren Campagne, Michiel M. van; Erneux, Cristophe; Eijk, Ronald van; Haastert, Peter J.M. van

    1988-01-01

    Dictyostelium discoideum homogenates contain phosphatase activity which rapidly dephosphorylates Ins(1,4,5)P3 (D-myo-inositol 1,4,5-trisphosphate) to Ins (myo-inositol). When assayed in Mg2+, Ins(1,4,5)P3 is dephosphorylated by the soluble Dictyostelium cell fraction to 20% Ins(1,4)P2 (D-myo-inosito

  9. Monitoring time-dependent maturation changes in purified phagosomes from Dictyostelium discoideum.

    Science.gov (United States)

    Dieckmann, Régis; Gopaldass, Navin; Escalera, Caroline; Soldati, Thierry

    2008-01-01

    The amoeba Dictyostelium discoideum is an established model to study phagocytosis. The sequence of events leading to the internalization and degradation of a particle is conserved in D. discoideum compared to metazoan cells. As its small haploid genome has been sequenced, it is now amenable to genome-wide analysis including organelle proteomics. Therefore, we adapted to Dictyostelium the classical protocol to purify phagosomes formed by ingestion of latex beads particles. The pulse-chase protocol detailed here gives easy access to pure, intact, and synchronized phagosomes from representative stages of the entire process of phagosome maturation. Recently, this protocol was used to generate individual temporal profiles of proteins and lipids during phagosome maturation generating a proteomic fingerprint of six maturation stages (1). In addition, immunolabeling of phagosomes on a coverslip was developed to visualize and quantitate antigen distribution at the level of individual phagosomes.

  10. Ground Testing of the EMCS Seed Cassette for Biocompatibility with the Cellular Slime Mold, Dictyostelium Discoideum

    Science.gov (United States)

    Hanely, Julia C.; Reinsch, Sigrid; Myers, Zachary A.; Freeman, John; Steele, Marianne K.; Sun, Gwo-Shing; Heathcote, David G.

    2014-01-01

    The European Modular Cultivation System, EMCS, was developed by ESA for plant experiments. To expand the use of flight verified hardware for various model organisms, we performed ground experiments to determine whether ARC EMCS Seed Cassettes could be adapted for use with cellular slime mold for future space flight experiments. Dictyostelium is a cellular slime mold that can exist both as a single-celled independent organism and as a part of a multicellular colony which functions as a unit (pseudoplasmodium). Under certain stress conditions, individual amoebae will aggregate to form multicellular structures. Developmental pathways are very similar to those found in Eukaryotic organisms, making this a uniquely interesting organism for use in genetic studies. Dictyostelium has been used as a genetic model organism for prior space flight experiments. Due to the formation of spores that are resistant to unfavorable conditions such as desiccation, Dictyostelium is also a good candidate for use in the EMCS Seed Cassettes. The growth substratum in the cassettes is a gridded polyether sulfone (PES) membrane. A blotter beneath the PES membranes contains dried growth medium. The goals of this study were to (1) verify that Dictyostelium are capable of normal growth and development on PES membranes, (2) develop a method for dehydration of Dictyostelium spores with successful recovery and development after rehydration, and (3) successful mock rehydration experiments in cassettes. Our results show normal developmental progression in two strains of Dictyostelium discoideum on PES membranes with a bacterial food source. We have successfully performed a mock rehydration of spores with developmental progression from aggregation to slug formation, and production of morphologically normal spores within 9 days of rehydration. Our results indicate that experiments on the ISS using the slime mold, Dictyostelium discoideum could potentially be performed in the flight verified hardware of

  11. Reconstitution of functional eukaryotic ribosomes from Dictyostelium discoideum ribosomal proteins and RNA.

    Science.gov (United States)

    Mangiarotti, G; Chiaberge, S

    1997-08-08

    40 and 60 S ribosomal subunits have been reconstituted in vitro from purified ribosomal RNA and ribosomal proteins of Dictyostelium discoideum. The functionality of the reconstituted ribosomes was demonstrated in in vitro mRNA-directed protein synthesis. The reassembly proceeded well with immature precursors of ribosomal RNA but poorly if at all with mature cytoplasmic RNA species. Reassembly also required a preparation of small nuclear RNA(s), acting as morphopoietic factor(s).

  12. Analysis of Rheb in the cellular slime mold Dictyostelium discoideum: Cellular localization, spatial expression and overexpression

    Indian Academy of Sciences (India)

    Pynskhem Bok Swer; Pooja Bhadoriya; Shweta Saran

    2014-03-01

    Dictyostelium discoideum encodes a single Rheb protein showing sequence similarity to human homologues of Rheb. The DdRheb protein shares 52% identity and 100% similarity with the human Rheb1 protein. Fluorescence of Rheb yellow fluorescent protein fusion was detected in the D. discoideum cytoplasm. Reverse transcription-polymerase chain reaction and whole-mount in situ hybridization analyses showed that rheb is expressed at all stages of development and in prestalk cells in the multicellular structures developed. When the expression of rheb as a fusion with lacZ was driven under its own promoter, the -galactosidase activity was seen in the prestalk cells. D. discoideum overexpressing Rheb shows an increase in the size of the cell. Treatment of the overexpressing Rheb cells with rapamycin confirms its involvement in the TOR signalling pathway.

  13. G-proteins and the inositol cycle in Dictyostelium discoideum

    NARCIS (Netherlands)

    Bominaar, Anthony; van der Kaay, Jeroen; Kesbeke, F.; Snaarjagalska, BE.; van Haastert, Peter; MILLIGAN, G; WAKELAM, MJO; KAY, J

    1990-01-01

    The inositol cycle in Dictyostelium disocideum was studied both in vitro and in vivo. The results are compared to the inositol cycle as it is known from higher eukaryotes. Although there is a strong resemblance the cycles are different at some essential points. In comparison to higher eukaryotes, in

  14. Variation, sex, and social cooperation: molecular population genetics of the social amoeba Dictyostelium discoideum.

    Directory of Open Access Journals (Sweden)

    Jonathan M Flowers

    2010-07-01

    Full Text Available Dictyostelium discoideum is a eukaryotic microbial model system for multicellular development, cell-cell signaling, and social behavior. Key models of social evolution require an understanding of genetic relationships between individuals across the genome or possibly at specific genes, but the nature of variation within D. discoideum is largely unknown. We re-sequenced 137 gene fragments in wild North American strains of D. discoideum and examined the levels and patterns of nucleotide variation in this social microbial species. We observe surprisingly low levels of nucleotide variation in D. discoideum across these strains, with a mean nucleotide diversity (pi of 0.08%, and no strong population stratification among North American strains. We also do not find any clear relationship between nucleotide divergence between strains and levels of social dominance and kin discrimination. Kin discrimination experiments, however, show that strains collected from the same location show greater ability to distinguish self from non-self than do strains from different geographic areas. This suggests that a greater ability to recognize self versus non-self may arise among strains that are more likely to encounter each other in nature, which would lead to preferential formation of fruiting bodies with clonemates and may prevent the evolution of cheating behaviors within D. discoideum populations. Finally, despite the fact that sex has rarely been observed in this species, we document a rapid decay of linkage disequilibrium between SNPs, the presence of recombinant genotypes among natural strains, and high estimates of the population recombination parameter rho. The SNP data indicate that recombination is widespread within D. discoideum and that sex as a form of social interaction is likely to be an important aspect of the life cycle.

  15. Effects of UV-B irradiation on sorocarp development of Dictyostelium discoideum

    Energy Technology Data Exchange (ETDEWEB)

    Haeder, D.P. (Marburg Univ. (Germany, F.R.). Botanisches Inst.)

    1983-11-01

    The effect of UV-B irradiation on the development of Dictyostelium discoideum from amoebae to mature sorocarps was studied. Radiation with wavelength <= 310 nm was very efficient in retarding and inhibiting the development especially when the organisms were exposed during the first 12 h. At a wavelength of 280 nm an irradiation of 1 h at an irradiance of < 0.2 W m/sup -2/ was sufficient to completely inhibit sorocarp development. The fluence-dependence shows as well that the development of D. discoideum is a very sensitive system to indicate UV-B irradiation. Furthermore, since the sorocarp development is concluded within 48 h it can serve as a fast bioassay for hazardous levels of increased UV-B irradiation which have been predicted as a result of the ozone reduction in the stratosphere due to the manmade production and emission of chlorofluoromethanes.

  16. The phylogeny of the aromatic amino acid hydroxylases revisited by characterizing phenylalanine hydroxylase from Dictyostelium discoideum.

    Science.gov (United States)

    Siltberg-Liberles, Jessica; Steen, Ida Helene; Svebak, Randi M; Martinez, Aurora

    2008-12-31

    The social amoeba Dictyostelium discoideum contains only one aromatic amino acid hydroxylase (AAAH) gene compared to at least three in metazoans. As shown in this work this gene codes for a phenylalanine hydroxylase (DictyoPAH) and phylogenetic analysis places this enzyme close to the precursor AAAHs, aiding to define the evolutionary history of the AAAH family. DictyoPAH shows significant similarities to other eukaryote PAH, but it exhibits higher activity with tetrahydrodictyopterin (DH4) than with tetrahydrobiopterin (BH4) as cofactor. DH4 is an abundant tetrahydropterin in D. discoideum while BH4 is the natural cofactor of the AAAHs in mammals. Moreover, DictyoPAH is devoid of the characteristic regulatory mechanisms of mammalian PAH such as positive cooperativity for L-Phe and activation by preincubation with the substrate. Analysis of the few active site substitutions between DictyoPAH and mammalian PAH, including mutant expression analysis, reveals potential structural determinants for allosteric regulation.

  17. Functional dissection of the dictyostelium discoideum dynamin B mitochondrial targeting sequence.

    Directory of Open Access Journals (Sweden)

    Amrita Rai

    Full Text Available Most mitochondrial proteins are nuclear encoded and synthesized in the cytosol with an N-terminal mitochondrial targeting sequence or presequence for subsequent import into mitochondria. Here, we describe the proteolytic processing and inner membrane potential-dependent translocation of a dynamin family member by the Dictyostelium discoideum mitochondrial import system. Our results show that the unusual D. discoideum dynamin B presequence is removed through a processing mechanism that is common for mitochondrial matrix proteins. We identified a minimal segment of the dynamin B presequence containing seven lysine residues. This 47-residue region is, in combination with consensus matrix protease cleavage sites, necessary and sufficient for mitochondrial targeting. The correct positioning of these lysine residues plays a critical role for the proper processing and mitochondrial import of dynamin B in D. discoideum. Fluorescent proteins tagged with the dynamin B presequence or presequence regions supporting mitochondrial import in D. discoideum are imported with similar efficiency into the mitochondrial matrix of mammalian cells, indicating that the basic mechanisms underlying mitochondrial protein import are highly conserved from amoebozoa to mammalia.

  18. The Dictyostelium discoideum cellulose synthase: Structure/function analysis and identification of interacting proteins

    Energy Technology Data Exchange (ETDEWEB)

    Richard L. Blanton

    2004-02-19

    OAK-B135 The major accomplishments of this project were: (1) the initial characterization of dcsA, the gene for the putative catalytic subunit of cellulose synthase in the cellular slime mold Dictyostelium discoideum; (2) the detection of a developmentally regulated event (unidentified, but perhaps a protein modification or association with a protein partner) that is required for cellulose synthase activity (i.e., the dcsA product is necessary, but not sufficient for cellulose synthesis); (3) the continued exploration of the developmental context of cellulose synthesis and DcsA; (4) the isolation of a GFP-DcsA-expressing strain (work in progress); and (5) the identification of Dictyostelium homologues for plant genes whose products play roles in cellulose biosynthesis. Although our progress was slow and many of our results negative, we did develop a number of promising avenues of investigation that can serve as the foundation for future projects.

  19. cAMP diffusion in Dictyostelium discoideum: A Green's function method

    Science.gov (United States)

    Calovi, Daniel S.; Brunnet, Leonardo G.; de Almeida, Rita M. C.

    2010-07-01

    A Green’s function method is developed to approach the spatiotemporal equations describing the cAMP production in Dictyostelium discoideum, markedly reducing numerical calculations times: cAMP concentrations and gradients are calculated just at the amoeba locations. A single set of parameters is capable of reproducing the different observed behaviors, from cAMP synchronization, spiral waves and reaction-diffusion patterns to streaming and mound formation. After aggregation, the emergence of a circular motion of amoebas, breaking the radial cAMP field symmetry, is observed.

  20. Cyclic 3', 5'-AMP relay in Dictyostelium discoideum: adaptation is independent of activation of adenylate cyclase

    OpenAIRE

    1983-01-01

    In Dictyostelium discoideum, binding of cAMP to high affinity surface receptors leads to a rapid activation of adenylate cyclase followed by subsequent adaptation within several minutes. The rate of secretion of [ 3H ]cAMP, which reflects the state of activation of the enzyme, was measured. Caffeine noncompetitively inhibited the response to cAMP. Inhibition was rapidly reversible and pretreatment of cells with caffeine for up to 22 min had little effect on the subsequent responsiveness to cA...

  1. Characterization of a 1,4-. beta. -D-glucan synthase from Dictyostelium discoideum

    Energy Technology Data Exchange (ETDEWEB)

    Blanton, R.L.

    1992-01-15

    Various aspects of research concerning Dictyostelium discoideum are presented. The initial focus of this project was upon: the characterization of potential probes for the cellulose synthase (antibody and nucleic acid), the determination of the cultural induction conditions of cellulose synthesis, the solubilization of the enzyme activity, the development of a non-inhibitory disruption buffer, the generation and isolation of mutant strains deficient in cellulose synthesis, and the development of the capability to determine the degree of polymerization of the in vitro product. I have briefly summarized our most significant findings with only selected data sets being shown in this report in the interest of brevity.

  2. The green tea catechin epigallocatechin gallate (EGCG blocks cell motility, chemotaxis and development in Dictyostelium discoideum.

    Directory of Open Access Journals (Sweden)

    Kyle J McQuade

    Full Text Available Catechins, flavanols found at high levels in green tea, have received significant attention due to their potential health benefits related to cancer, autoimmunity and metabolic disease, but little is known about the mechanisms by which these compounds affect cellular behavior. Here, we assess whether the model organism Dictyostelium discoideum is a useful tool with which to characterize the effects of catechins. Epigallocatechin gallate (EGCG, the most abundant and potent catechin in green tea, has significant effects on the Dictyostelium life cycle. In the presence of EGCG aggregation is delayed, cells do not stream and development is typically stalled at the loose aggregate stage. The developmental effects very likely result from defects in motility, as EGCG reduces both random movement and chemotaxis of Dictyostelium amoebae. These results suggest that catechins and their derivatives may be useful tools with which to better understand cell motility and development in Dictyostelium and that this organism is a useful model to further characterize the activities of catechins.

  3. Derivatives of Dictyostelium differentiation-inducing factors inhibit lysophosphatidic acid–stimulated migration of murine osteosarcoma LM8 cells

    Energy Technology Data Exchange (ETDEWEB)

    Kubohara, Yuzuru, E-mail: ykuboha@juntendo.ac.jp [Department of Molecular and Cellular Biology, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8512 (Japan); Department of Health Science, Juntendo University Graduate School of Health and Sports Science, Inzai 270-1695 (Japan); Komachi, Mayumi [Department of Molecular and Cellular Biology, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8512 (Japan); Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi 371-8511 (Japan); Homma, Yoshimi [Department of Biomolecular Science, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine, Fukushima 960-1295 (Japan); Kikuchi, Haruhisa; Oshima, Yoshiteru [Laboratory of Natural Product Chemistry, Tohoku University Graduate School of Pharmaceutical Sciences, Aoba-yama, Aoba-ku, Sendai 980-8578 (Japan)

    2015-08-07

    Osteosarcoma is a common metastatic bone cancer that predominantly develops in children and adolescents. Metastatic osteosarcoma remains associated with a poor prognosis; therefore, more effective anti-metastatic drugs are needed. Differentiation-inducing factor-1 (DIF-1), −2, and −3 are novel lead anti-tumor agents that were originally isolated from the cellular slime mold Dictyostelium discoideum. Here we investigated the effects of a panel of DIF derivatives on lysophosphatidic acid (LPA)-induced migration of mouse osteosarcoma LM8 cells by using a Boyden chamber assay. Some DIF derivatives such as Br-DIF-1, DIF-3(+2), and Bu-DIF-3 (5–20 μM) dose-dependently suppressed LPA-induced cell migration with associated IC{sub 50} values of 5.5, 4.6, and 4.2 μM, respectively. On the other hand, the IC{sub 50} values of Br-DIF-1, DIF-3(+2), and Bu-DIF-3 versus cell proliferation were 18.5, 7.2, and 2.0 μM, respectively, in LM8 cells, and >20, 14.8, and 4.3 μM, respectively, in mouse 3T3-L1 fibroblasts (non-transformed). Together, our results demonstrate that Br-DIF-1 in particular may be a valuable tool for the analysis of cancer cell migration, and that DIF derivatives such as DIF-3(+2) and Bu-DIF-3 are promising lead anti-tumor agents for the development of therapies that suppress osteosarcoma cell proliferation, migration, and metastasis. - Highlights: • LPA induces cell migration (invasion) in murine osteosarcoma LM8 cells. • DIFs are novel lead anti-tumor agents found in Dictyostelium discoideum. • We examined the effects of DIF derivatives on LPA-induced LM8 cell migration in vitro. • Some of the DIF derivatives inhibited LPA-induced LM8 cell migration.

  4. Biochemical basis of the high resistance to oxidative stress in Dictyostelium discoideum

    Indian Academy of Sciences (India)

    Bandhana Katoch; Rasheedunnisa Begum

    2003-09-01

    Aerobic organisms experience oxidative stress due to generation of reactive oxygen species during normal aerobic metabolism. In addition, several chemicals also generate reactive oxygen species which induce oxidative stress. Thus oxidative stress constitutes a major threat to organisms living in aerobic environments. Programmed cell death or apoptosis is a physiological mechanism of cell death, that probably evolved with multicellularity, and is indispensable for normal growth and development. Dictyostelium discoideum, an eukaryotic developmental model, shows both unicellular and multicellular forms in its life cycle and exhibits apparent caspase-independent programmed cell death, and also shows high resistance to oxidative stress. An attempt has been made to investigate the biochemical basis for high resistance of D. discoideum cell death induced by different oxidants. Dose-dependent induction of cell death by exogenous addition of hydrogen peroxide (H2O2), in situ generation of H2O2 by hydroxylamine, and nitric oxide (NO) generation by sodium nitroprusside treatment in D. discoideum were studied. The AD50 doses (concentration of the oxidants cusing 50% of the cells to die) after 24 h of treatment were found to be 0.45 mM, 4 mM and 1 mM, respectively. Studies on enzymatic antioxidant status of D. discoideum when subjected to oxidative stress, NO and nutrient stress reveal that superoxide dismutase and catalase were unchanged; a significant induction of glutathione peroxidase was observed. Interestingly, oxidative stress-induced lipid membrane peroxidative damage could not be detected. The results shed light on the biochemical basis for the observed high resistance to oxidative stress in D. discoideum.

  5. Filamin repeat segments required for photosensory signalling in Dictyostelium discoideum

    Directory of Open Access Journals (Sweden)

    Ahmed Afsar U

    2007-11-01

    Full Text Available Abstract Background Filamin is an actin binding protein which is ubiquitous in eukaryotes and its basic structure is well conserved – an N-terminal actin binding domain followed by a series of repeated segments which vary in number in different organisms. D. discoideum is a well established model organism for the study of signalling pathways and the actin cytoskeleton and as such makes an excellent organism in which to study filamin. Ddfilamin plays a putative role as a scaffolding protein in a photosensory signalling pathway and this role is thought to be mediated by the unusual repeat segments in the rod domain. Results To study the role of filamin in phototaxis, a filamin null mutant, HG1264, was transformed with constructs each of which expressed wild type filamin or a mutant filamin with a deletion of one of the repeat segments. Transformants expressing the full length filamin to wild type levels completely rescued the phototaxis defect in HG1264, however if filamin was expressed at lower than wild type levels the phototaxis defect was not restored. The transformants lacking any one of the repeat segments 2–6 retained defective phototaxis and thermotaxis phenotypes, whereas transformants expressing filaminΔ1 exhibited a range of partial complementation of the phototaxis phenotype which was related to expression levels. Immunofluorescence microscopy showed that filamin lacking any of the repeat segments still localised to the same actin rich areas as wild type filamin. Ddfilamin interacts with RasD and IP experiments demonstrated that this interaction did not rely upon any single repeat segment or the actin binding domain. Conclusion This paper demonstrates that wild type levels of filamin expression are essential for the formation of functional photosensory signalling complexes and that each of the repeat segments 2–6 are essential for filamins role in phototaxis. By contrast, repeat segment 1 is not essential provided the mutated

  6. Caffeine sensitive repair and mutation induction in UV- or. gamma. -ray-irradiated Dictyostelium discoideum

    Energy Technology Data Exchange (ETDEWEB)

    Kanishi, Nobuji (Tokyo Metropolitan Research Lab. of Public Health (Japan)); Kinjo, Yasuhito; Watanabe, Makoto

    1990-01-01

    It seems that certain kinds of chemical substances increase the distortion in molecules, change the high order microstructures of nuclei and chromosomes, and exert large variation to the function of repairing the damage of genes due to radiation and others, by coupling with DNA, protein or enzyme system. It has been well known that caffeine is one of such compounds, and by coupling with DNA, it increases the damage due to ultraviolet ray and gives the action of obstructing repair in addition to the action of inducing the abnormality of chromosomes and mutation. Dictyostelium discoideum has the simplest nuclear structure, and shows extremely high resistance to radiation by its high restoration ability. The authors have advanced the research by paying attention to its characteristics, and comparing the Dictyostelium discoideum as one model system with the lymphocyte system of higher animals. This time, the authors analyzed the characteristics of two kinds of sensitivity repair process of caffeine, and investigated into their relation with the occurrence of mutation. The experimental method and the results are reported. (K.I.).

  7. A Method for Studying cAMP-relay in Dictyostelium discoideum : the Effect of Temperature on cAMP-relay

    NARCIS (Netherlands)

    Haastert, Peter J.M. van

    1984-01-01

    A simple assay has been developed to quantify the cAMP-relay in Dictyostelium discoideum. The assay is based on the stimulation of cells, in the presence of a phosphodiesterase inhibitor, with 2'-deoxyadenosine 3',5'-monophosphate (dcAMP) at a concentration which saturates cell surface cAMP receptor

  8. Isolation and Partial Characterization of a Cyclic GMP-Dependent Cyclic GMP-Specific Phosphodiesterase from Dictyostelium discoideum

    NARCIS (Netherlands)

    Bulgakov, Roman; Haastert, Peter J.M. van

    1983-01-01

    The cellular slime mold, Dictyostelium discoideum, contains at least two classes of phosphodiesterase activity. One class of enzymes hydrolyses cyclic AMP (cAMP) and cyclic GMP (cGMP) with approximately equal rates. Another enzyme, which is less than 5% of the total activity, specifically hydrolyses

  9. Motile activities of Dictyostelium discoideum differ from those in Protista or vertebrate animal cells.

    Science.gov (United States)

    Waligórska, Agnieszka; Wianecka-Skoczeń, Magdalena; Korohoda, Włodzimierz

    2007-01-01

    Cell movement in the amoebae Dictyostelium discoideum has been examined in media differing in monovalent cation concentration (i.e. Na+ and K+). Under isotonic or even slightly hypertonic conditions, the cells move equally well in solutions in which either potassium or sodium ions dominate. However, in strongly hypertonic solutions the amoebae showed motility in a 2% potassium chloride solution, but remained motionless in a hypertonic 2% sodium chloride solution. This inhibition of D. discoideum amoebae movement in a hypertonic sodium chloride solution was fully reversible. Such behaviour corresponds to that of plant, fungi, and some invertebrate animal cells rather than protozoan or vertebrate cells. These observations suggest that studies using D. discoideum as a model for cell motility in vertebrate animal tissue cells should be considered with caution, and would seem to confirm the classification of cellular slime moulds as related rather to Fungi than to Protista. This also shows that the cell membrane models should consider the asymmetry in sodium/potassium ion concentrations found in vertebrate animal cells as one of various possibilities.

  10. Lipid composition of multilamellar bodies secreted by Dictyostelium discoideum reveals their amoebal origin.

    Science.gov (United States)

    Paquet, Valérie E; Lessire, René; Domergue, Frédéric; Fouillen, Laetitia; Filion, Geneviève; Sedighi, Ahmadreza; Charette, Steve J

    2013-10-01

    When they are fed with bacteria, Dictyostelium discoideum amoebae produce and secrete multilamellar bodies (MLBs), which are composed of membranous material. It has been proposed that MLBs are a waste disposal system that allows D. discoideum to eliminate undigested bacterial remains. However, the real function of MLBs remains unknown. Determination of the biochemical composition of MLBs, especially lipids, represents a way to gain information about the role of these structures. To allow these analyses, a protocol involving various centrifugation procedures has been developed to purify secreted MLBs from amoeba-bacterium cocultures. The purity of the MLB preparation was confirmed by transmission electron microscopy and by immunofluorescence using H36, an antibody that binds to MLBs. The lipid and fatty acid compositions of pure MLBs were then analyzed by high-performance thin-layer chromatography (HPTLC) and gas chromatography (GC), respectively, and compared to those of amoebae as well as bacteria used as a food source. While the bacteria were devoid of phosphatidylcholine (PC) and phosphatidylinositol (PI), these two polar lipid species were major classes of lipids in MLBs and amoebae. Similarly, the fatty acid composition of MLBs and amoebae was characterized by the presence of polyunsaturated fatty acids, while cyclic fatty acids were found only in bacteria. These results strongly suggest that the lipids constituting the MLBs originate from the amoebal metabolism rather than from undigested bacterial membranes. This opens the possibility that MLBs, instead of being a waste disposal system, have unsuspected roles in D. discoideum physiology.

  11. Lack of ecological context can create the illusion of social success in Dictyostelium discoideum

    CERN Document Server

    Martinez-Garcia, Ricardo

    2016-01-01

    Studies of cooperation in microbes often focus on one fitness component, with little information about or attention to the ecological context, and this can lead to paradoxical results. The life cycle of the social amoeba Dictyostelium discoideum includes a multicellular stage in which not necessarily clonal amoebae aggregate upon starvation to form a possibly chimeric (genetically heterogeneous) fruiting body made of dead stalk and spores. The lab-measured reproductive skew in the spores of chimeras indicates strong social antagonism; this should result in low genotypic diversity, which is inconsistent with observations from nature. Two studies have suggested that this inconsistency stems from the one-dimensional assessment of fitness (spore production) and that the solution lies in tradeoffs between multiple traits, e.g.: spore size versus viability; and staying vegetative versus becoming dormant. We theoretically explore different tradeoff-implementing mechanisms and provide a unifying ecological framework ...

  12. Cloning and characterization of the Dictyostelium discoideum rasG genomic sequences.

    Science.gov (United States)

    Robbins, S M; Williams, J G; Spiegelman, G B; Weeks, G

    1992-02-28

    A Dictyostelium discoideum genomic DNA clone containing the ras-related gene, rasG was isolated using the rasG cDNA as a probe. The genomic clone encompasses the entire coding region of the gene and 1.5 kb of 5' flanking region. The rasG gene contains a single intron as determined by sequence comparison with the cDNA, whereas the highly related rasD gene contains three introns. Primer extension analysis showed that transcription of the rasG gene initiates at multiple sites. Sequence analysis of the 5' flanking region of the gene revealed a stretch of thymine residues upstream from the transcription start sites but there is no evidence for a TATA box sequence.

  13. Formation of non-viable spores of Dictyostelium discoideum by UV-irradiation and caffeine

    Energy Technology Data Exchange (ETDEWEB)

    Ohnishi, T.; Hazama, M.; Okaichi, K.; Nozu, K. (Nara Medical Univ., Kashihara (Japan))

    1982-09-01

    The spores formed from amoeboid cells of the wild type strain of Dictyostelium discoideum after UV-irradiation were characterized. Cell differentiation in the presence of caffeine after a fluence of 300 J/m/sup 2/ resulted in a population of spores which was 98% non-viable. The UV-irradiation did not affect the conversion of the spores to swollen spores but did affect the conversion of swollen spores to amoeboid cells. When the germination of the spores was done without caffeine, only a small effect on conversion of swollen spores to amoeboid cells and on the beginning of growth was detected. On the other hand, in the presence of caffeine, the spores had a remarkable delay in both. It was also shown that few, if any, pyrimidine dimers exist in the DNA of the non-viable spores. Possible mechanisms of formation of non-viable spores are discussed.

  14. Oxygen effect in survival of Dictyostelium discoideum treated with near ultraviolet radiation

    Energy Technology Data Exchange (ETDEWEB)

    Graetzer, R.

    1987-03-01

    Fluence-response survival curves have been measured for the cellular slime mold Dictyo-stelium discoideum exposed to near ultraviolet radiation. Data were obtained for a wild type strain and three UV-sensitive mutant strains in exponential growth phase. Fluences for 10% survival (F/sub 10/) are about 1 MJ m/sup -2/ for cells irradiated in saline solution saturated with nitrogen. When air is bubbled through the saline, the F/sub 10/ values are only one third as large. Strain HPS50, which is the strain most sensitive to gamma radiation and to 254 nm UV, also exhibits the greatest sensitivity to near UV. However, the difference in sensitivity to near UV between wild type and mutant strains is small compared to other physical and chemical agents known to damage DNA.

  15. Cyclic AMP stabilizes a class of developmentally regulated Dictyostelium discoideum mRNAs.

    Science.gov (United States)

    Mangiarotti, G; Ceccarelli, A; Lodish, H F

    The stability of mRNA is an important facet of the regulation of protein synthesis. In mammalian cells most mRNAs have long half-lives (5-15 hours) but a substantial fraction are much less stable. There are few examples where the stability of a particular mRNA or class of mRNAs is specifically affected by environmental or developmental stimuli. Certain hormones cause specific stabilization of mRNAs species and preferential mRNA stability is important in the accumulation of globin and myosin mRNAs during the terminal stages of erythropoesis or myogenesis, respectively. Disaggregation of Dictyostelium discoideum aggregates induces the specific destabilization of a large class of developmentally regulated mRNAs; thus, this system is an excellent one in which to determine how such controls are effected. Here we show that addition of cyclic AMP to disaggregated cells specifically prevents the destabilization of these mRNAs.

  16. rRNA maturation as a "quality" control step in ribosomal subunit assembly in Dictyostelium discoideum.

    Science.gov (United States)

    Mangiarotti, G; Chiaberge, S; Bulfone, S

    1997-10-31

    In Dictyostelium discoideum, newly assembled ribosomal subunits enter polyribosomes while they still contain immature rRNA. rRNA maturation requires the engagement of the subunits in protein synthesis and leads to stabilization of their structure. Maturation of pre-17 S rRNA occurs only after the newly formed 40 S ribosomal particle has entered an 80 S ribosome and participated at least in the formation of one peptide bond or in one translocation event; maturation of pre-26 S rRNA requires the presence on the 80 S particle of a peptidyl-tRNA containing at least 6 amino acids. Newly assembled particles that cannot fulfill these requirements for structural reasons are disassembled into free immature rRNA and ribosomal proteins.

  17. Covalent modifications of ribosomal proteins in growing and aggregation-competent dictyostelium discoideum: phosphorylation and methylation.

    Science.gov (United States)

    Ramagopal, S

    1991-04-01

    Phosphorylated and methylated ribosomal proteins were identified in vegetatively growing amoebae and in the starvation-induced, aggregation-competent cells of Dictyostelium discoideum. Of the 15 developmentally regulated cell-specific ribosomal proteins reported earlier, protein A and the acidic proteins A1, A2, and A3 were identified as phosphoproteins, and S5, S6, S10, and D were identified as methylated proteins. Three other ribosomal proteins were phosphorylated and 19 others methylated. S19, L13, A1, A2, and A3 were the predominant phosphoproteins in growing amoebae, whereas S20 and A were the predominant ones in the aggregation-competent cells. Among the methylated proteins, eight (S6, S10, S13, S30, D, L1, L2, and L31) were modified only during growth phase, six (S5, S7, S8, S24, S31, and L36) were altered only during aggregation-competent phase, and nine (S9, S27, S28, S29, S34, L7, L35, L41, and L42) were modified under both phases. Five proteins (S6, S24, L7, L41, and L42) were heavily methylated and of these, the large subunit proteins were present in both growing amoebae and aggregation-competent cells. These findings demonstrate that covalent modification of specific ribosomal proteins is regulated during cell differentiation in D. discoideum.

  18. Calcium regulates the expression of a Dictyostelium discoideum asparaginyl tRNA synthetase gene

    Indian Academy of Sciences (India)

    Jyoti K Jaiswal; Vidyanand Nanjundiah

    2003-12-01

    In a screen for calcium-regulated gene expression during growth and development of Dictyostelium discoideum we have identified an asparaginyl tRNA synthetase (ddAsnRS) gene, the second tRNA synthetase gene identified in this organism. The ddAsnRS gene shows many unique features. One, it is repressed by lowering cellular calcium, making it the first known calcium-regulated tRNA synthetase. Two, despite the calcium-dependence, its expression is unaltered during the cell cycle, making this the first D. discoideum gene to show a calcium-dependent but cell cycle phase-independent expression. Finally, the N-terminal domain of the predicted ddAsnRS protein shows higher sequence similarity to Glutaminyl tRNA synthetases than to other Asn tRNA synthetases. These unique features of the AsnRS from this primitive eukaryote not only point to a novel mechanism regulating the components of translation machinery and gene expression by calcium, but also hint at a link between the evolution of GlnRS and AsnRS in eukaryotes.

  19. Sentinel cells, symbiotic bacteria and toxin resistance in the social amoeba Dictyostelium discoideum.

    Science.gov (United States)

    Brock, Debra A; Callison, W Éamon; Strassmann, Joan E; Queller, David C

    2016-04-27

    The social amoeba Dictyostelium discoideum is unusual among eukaryotes in having both unicellular and multicellular stages. In the multicellular stage, some cells, called sentinels, ingest toxins, waste and bacteria. The sentinel cells ultimately fall away from the back of the migrating slug, thus removing these substances from the slug. However, some D. discoideum clones (called farmers) carry commensal bacteria through the multicellular stage, while others (called non-farmers) do not. Farmers profit from their beneficial bacteria. To prevent the loss of these bacteria, we hypothesize that sentinel cell numbers may be reduced in farmers, and thus farmers may have a diminished capacity to respond to pathogenic bacteria or toxins. In support, we found that farmers have fewer sentinel cells compared with non-farmers. However, farmers produced no fewer viable spores when challenged with a toxin. These results are consistent with the beneficial bacteria Burkholderia providing protection against toxins. The farmers did not vary in spore production with and without a toxin challenge the way the non-farmers did, which suggests the costs of Burkholderia may be fixed while sentinel cells may be inducible. Therefore, the costs for non-farmers are only paid in the presence of the toxin. When the farmers were cured of their symbiotic bacteria with antibiotics, they behaved just like non-farmers in response to a toxin challenge. Thus, the advantages farmers gain from carrying bacteria include not just food and protection against competitors, but also protection against toxins. © 2016 The Author(s).

  20. Effects of a 50 Hz magnetic field on Dictyostelium discoideum (Protista).

    Science.gov (United States)

    Amaroli, Andrea; Trielli, Francesca; Bianco, Bruno; Giordano, Stefano; Moggia, Elsa; Corrado, Maria Umberta Delmonte

    2006-10-01

    Some studies have demonstrated that a few biological systems are affected by weak, extremely low frequency (ELF) electromagnetic fields (EMFs), lower than 10 mT. However, to date there is scanty evidence of this effect on Protists in the literature. Due to their peculiarity as single-cell eukaryotic organisms, Protists respond directly to environmental stimuli, thus appearing as very suitable experimental systems. Recently, we showed the presence of propionylcholinesterase (PrChE) activity in single-cell amoebae of Dictyostelium discoideum. This enzyme activity was assumed to be involved in cell-cell and cell-environment interactions, as its inhibition affects cell aggregation and differentiation. In this work, we have exposed single-cell amoebae of D. discoideum to an ELF-EMF of about 200 microT, 50 Hz, for 3 h or 24 h at 21 degrees C. A delay in the early phase of the differentiation was observed in 3 h exposed cells, and a significant decrease in the fission rate appeared in 24 h exposed cells. The PrChE activity was significantly lower in 3 h exposed cells than in the controls, whereas 24 h exposed cells exhibited an increase in this enzyme activity. However, such effects appeared to be transient, as the fission rate and PrChE activity values returned to the respective control values after a 24 h stay under standard conditions.

  1. Nucleocytoplasmic protein translocation during mitosis in the social amoebozoan Dictyostelium discoideum.

    Science.gov (United States)

    O'Day, Danton H; Budniak, Aldona

    2015-02-01

    Mitosis is a fundamental and essential life process. It underlies the duplication and survival of all cells and, as a result, all eukaryotic organisms. Since uncontrolled mitosis is a dreaded component of many cancers, a full understanding of the process is critical. Evolution has led to the existence of three types of mitosis: closed, open, and semi-open. The significance of these different mitotic species, how they can lead to a full understanding of the critical events that underlie the asexual duplication of all cells, and how they may generate new insights into controlling unregulated cell division remains to be determined. The eukaryotic microbe Dictyostelium discoideum has proved to be a valuable biomedical model organism. While it appears to utilize closed mitosis, a review of the literature suggests that it possesses a form of mitosis that lies in the middle between truly open and fully closed mitosis-it utilizes a form of semi-open mitosis. Here, the nucleocytoplasmic translocation patterns of the proteins that have been studied during mitosis in the social amoebozoan D. discoideum are detailed followed by a discussion of how some of them provide support for the hypothesis of semi-open mitosis.

  2. Xpf and not the Fanconi anaemia proteins or Rev3 accounts for the extreme resistance to cisplatin in Dictyostelium discoideum.

    Directory of Open Access Journals (Sweden)

    Xiao-Yin Zhang

    2009-09-01

    Full Text Available Organisms like Dictyostelium discoideum, often referred to as DNA damage "extremophiles", can survive exposure to extremely high doses of radiation and DNA crosslinking agents. These agents form highly toxic DNA crosslinks that cause extensive DNA damage. However, little is known about how Dictyostelium and the other "extremophiles" can tolerate and repair such large numbers of DNA crosslinks. Here we describe a comprehensive genetic analysis of crosslink repair in Dictyostelium discoideum. We analyse three gene groups that are crucial for a replication-coupled repair process that removes DNA crosslinks in higher eukarya: The Fanconi anaemia pathway (FA, translesion synthesis (TLS, and nucleotide excision repair. Gene disruption studies unexpectedly reveal that the FA genes and the TLS enzyme Rev3 play minor roles in tolerance to crosslinks in Dictyostelium. However, disruption of the Xpf nuclease subcomponent results in striking hypersensitivity to crosslinks. Genetic interaction studies reveal that although Xpf functions with FA and TLS gene products, most Xpf mediated repair is independent of these two gene groups. These results suggest that Dictyostelium utilises a distinct Xpf nuclease-mediated repair process to remove crosslinked DNA. Other DNA damage-resistant organisms and chemoresistant cancer cells might adopt a similar strategy to develop resistance to DNA crosslinking agents.

  3. Mechanism of oligomerisation of cyclase-associated protein from Dictyostelium discoideum in solution.

    Science.gov (United States)

    Yusof, Adlina Mohd; Jaenicke, Elmar; Pedersen, Jan Skov; Noegel, Angelika A; Schleicher, Michael; Hofmann, Andreas

    2006-10-06

    Cyclase-associated protein (CAP) is a highly conserved modular protein implicated in the regulation of actin filament dynamics and a variety of developmental and morphological processes. The protein exists as a high molecular weight complex in cell extracts and purified protein possesses a high tendency to aggregate, a major obstacle for crystallisation. Using a mutagenesis approach, we show that two structural features underlie the mechanism of oligomerisation in Dictyostelium discoideum CAP. Positively charged clusters on the surface of the N-terminal helix-barrel domain are involved in inter-molecular interactions with the N or C-terminal domains. Abolishing these interactions mainly renders dimers due to a domain swap feature in the extreme C-terminal region of the protein that was previously described. Based on earlier studies with yeast CAP, we also generated constructs with mutations in the extreme N-terminal region of Dictyostelium CAP that did not show significantly altered oligomerisation behaviour. Constructs with mutations in the earlier identified protein-protein interaction interface on the N-terminal domain of CAP could not be expressed as soluble protein. Assessment of the soluble proteins indicates that the mutations did not affect their overall fold. Further studies point to the correlation between stability of full-length CAP with its multimerisation behaviour, where oligomer formation leads to a more stable protein.

  4. Caspase-like proteins: Acanthamoeba castellanii metacaspase and Dictyostelium discoideum paracaspase, what are their functions?

    Indian Academy of Sciences (India)

    Entsar Saheb; Wendy Trzyna; John Bush

    2014-12-01

    Caspases are cysteine proteases that are important regulators of programmed cell death in animals. Two novel relatives to members of the caspase families metacaspases and paracaspase have been discovered. Metacaspase type-1 was identified in Acanthamoeba castellanii, an opportunistic protozoan parasite that causes severe diseases in humans. Paracaspase was found in the non-pathogenic protozoan Dictyostelium discoideum. Since their discovery in Acanthamoeba and Dictyostelium, metacaspases and paracaspases have remained poorly characterized. At present we do not have sufficient data about the molecular function of these caspase-like proteins or their role, if any, in programmed cell death. How these caspase proteins function at the molecular level is an important area of study that will provide insight into their potential for treatment therapies against Acanthamoeba infection and other similar parasitic protozoan. Additionally, finding the molecular functions of these caspase-like proteins will provide information concerning their role in more complex organisms.The aim of this article was to review recent discoveries about metacaspases and paracaspases as regulators of apoptotic and non-apoptotic processes.

  5. Cell adhesion molecules regulate contractile ring-independent cytokinesis in Dictyostelium discoideum

    Institute of Scientific and Technical Information of China (English)

    Akira Nagasaki; Masamitsu Kanada; Taro QP Uyeda

    2009-01-01

    To investigate the roles of substrate adhesion in cytokinesis, we established cell lines lacking paxiUin (PAXB) or vinculin (VINA), and those expressing the respective GFP fusion proteins in Dictyostelium discoideum. As in mammalian cells, GFP-PAXB and GFP-VINA formed focal adhesion-like complexes on the cell bottom, paxB cells in suspension grew normally, but on substrates, often failed to divide after regression of the furrow. The efficient cytokinesis of paxB cells in suspension is not because of shear forces to assist abscission, as they divided normally in static suspension culture as well. Double knockout strains lacking mhcA, which codes for myosin I1, and paxB or vinA displayed more severe cytokinetic defects than each single knockout strain. In mitotic wild-type cells, GFP-PAXB was diffusely distributed on the basal membrane, but was strikingly condensed along the polar edges in mitotic mhcA cells. These results are consistent with our idea that Dictyostelium displays two forms of cytokinesis, one that is contractile ringdependent and adhesion-independent, and the other that is contractile ring-independent and adhesion-dependent, and that the latter requires PAXB and VINA. Furthermore, that paxB cells fail to divide normally in the presence of substrate adhesion suggests that this adhesion molecule may play additional signaling roles.

  6. Biosynthesis of Dictyostelium Discoideum Differentation-Inducing Factor by a Hybrid Type I Fatty Acid A-Type III polyketide synthase

    Energy Technology Data Exchange (ETDEWEB)

    Austin,M.; Saito, T.; Bowman, M.; Haydock, S.; Kato, A.; Moore, B.; Kay, R.; Noel, J.

    2006-01-01

    Differentiation-inducing factors (DIFs) are well known to modulate formation of distinct communal cell types from identical Dictyostelium discoideum amoebas, but DIF biosynthesis remains obscure. We report complimentary in vivo and in vitro experiments identifying one of two {approx}3,000-residue D. discoideum proteins, termed 'steely', as responsible for biosynthesis of the DIF acylphloroglucinol scaffold. Steely proteins possess six catalytic domains homologous to metazoan type I fatty acid synthases (FASs) but feature an iterative type III polyketide synthase (PKS) in place of the expected FAS C-terminal thioesterase used to off load fatty acid products. This new domain arrangement likely facilitates covalent transfer of steely N-terminal acyl products directly to the C-terminal type III PKS active sites, which catalyze both iterative polyketide extension and cyclization. The crystal structure of a steely C-terminal domain confirms conservation of the homodimeric type III PKS fold. These findings suggest new bioengineering strategies for expanding the scope of fatty acid and polyketide biosynthesis.

  7. A RabGAP regulates life-cycle duration via trimeric G-protein cascades in Dictyostelium discoideum.

    Directory of Open Access Journals (Sweden)

    Hidekazu Kuwayama

    Full Text Available BACKGROUND: The life-cycle of cellular slime molds comprises chronobiologically regulated processes. During the growth phase, the amoeboid cells proliferate at a definite rate. Upon starvation, they synthesize cAMP as both first and second messengers in signalling pathways and form aggregates, migrating slugs, and fruiting bodies, consisting of spores and stalk cells, within 24 h. In Dictyostelium discoideum, because most growth-specific events cease during development, proliferative and heterochronic mutations are not considered to be interrelated and no genetic factor governing the entire life-cycle duration has ever been identified. METHODOLOGY/PRINCIPAL FINDINGS: Using yeast 2-hybrid library screening, we isolated a Dictyostelium discoideum RabGAP, Dd Rbg-3, as a candidate molecule by which the Dictyostelium Gα2 subunit directs its effects. Rab GTPase-activating protein, RabGAP, acts as a negative regulator of Rab small GTPases, which orchestrate the intracellular membrane trafficking involved in cell proliferation. Deletion mutants of Dd rbg-3 exhibited an increased growth rate and a shortened developmental period, while an overexpression mutant demonstrated the opposite effects. We also show that Dd Rbg-3 interacts with 2 Gα subunits in an activity-dependent manner in vitro. Furthermore, both human and Caenorhabditis elegans rbg-3 homologs complemented the Dd rbg-3-deletion phenotype in D. discoideum, indicating that similar pathways may be generally conserved in multicellular organisms. CONCLUSIONS/SIGNIFICANCE: Our findings suggest that Dd Rbg-3 acts as a key element regulating the duration of D. discoideum life-span potentially via trimeric G-protein cascades.

  8. Identifying the molecular basis of functions in the transcriptome of the social amoeba Dictyostelium discoideum.

    Science.gov (United States)

    Whitney, T J; Gardner, D G; Mott, M L; Brandon, M

    2010-03-09

    The unusual life cycle of Dictyostelium discoideum, in which an extra-cellular stressor such as starvation induces the development of a multicellular fruiting body consisting of stalk cells and spores from a culture of identical amoebae, provides an excellent model for investigating the molecular control of differentiation and the transition from single- to multi-cellular life, a key transition in development. We utilized serial analysis of gene expression (SAGE), a molecular method that is unbiased by dependence on previously identified genes, to obtain a transcriptome from a high-density culture of amoebae, in order to examine the transition to multi-cellular development. The SAGE method provides relative expression levels, which allows us to rank order the expressed genes. We found that a large number of ribosomal proteins were expressed at high levels, while various components of the proteosome were expressed at low levels. The only identifiable transmembrane signaling system components expressed in amoebae are related to quorum sensing, and their expression levels were relatively low. The most highly expressed gene in the amoeba transcriptome, dutA untranslated RNA, is a molecule with unknown function that may serve as an inhibitor of translation. These results suggest that high-density amoebae have not initiated development, and they also suggest a mechanism by which the transition into the development program is controlled.

  9. A quorum-sensing factor in vegetative Dictyostelium discoideum cells revealed by quantitative migration analysis.

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    Laurent Golé

    Full Text Available BACKGROUND: Many cells communicate through the production of diffusible signaling molecules that accumulate and once a critical concentration has been reached, can activate or repress a number of target genes in a process termed quorum sensing (QS. In the social amoeba Dictyostelium discoideum, QS plays an important role during development. However little is known about its effect on cell migration especially in the growth phase. METHODS AND FINDINGS: To investigate the role of cell density on cell migration in the growth phase, we use multisite timelapse microscopy and automated cell tracking. This analysis reveals a high heterogeneity within a given cell population, and the necessity to use large data sets to draw reliable conclusions on cell motion. In average, motion is persistent for short periods of time (t ≤ 5 min, but normal diffusive behavior is recovered over longer time periods. The persistence times are positively correlated with the migrated distances. Interestingly, the migrated distance decreases as well with cell density. The adaptation of cell migration to cell density highlights the role of a secreted quorum sensing factor (QSF on cell migration. Using a simple model describing the balance between the rate of QSF generation and the rate of QSF dilution, we were able to gather all experimental results into a single master curve, showing a sharp cell transition between high and low motile behaviors with increasing QSF. CONCLUSION: This study unambiguously demonstrates the central role played by QSF on amoeboid motion in the growth phase.

  10. Autonomous and non-autonomous traits mediate social cooperation in Dictyostelium discoideum

    Indian Academy of Sciences (India)

    Nameeta Mujumdar; Ashvini Kumar Dubey; Krithi Nandimath; Vidyanand Nanjundiah

    2011-08-01

    In the trishanku (triA−) mutant of the social amoeba Dictyostelium discoideum, aggregates are smaller than usual and the spore mass is located mid-way up the stalk, not at the apex. We have monitored aggregate territory size, spore allocation and fruiting body morphology in chimaeric groups of (quasi-wild-type) Ax2 and triA− cells. Developmental canalisation breaks down in chimaeras and leads to an increase in phenotypic variation. A minority of triA− cells causes largely Ax2 aggregation streams to break up; the effect is not due to the counting factor. Most chimaeric fruiting bodies resemble those ofAx2 or triA−. Others are double-deckers with a single stalk and two spore masses, one each at the terminus and midway along the stalk. The relative number of spores belonging to the two genotypes depends both on the mixing ratio and on the fruiting body morphology. In double-deckers formed from 1:1 chimaeras, the upper spore mass has more Ax2 spores, and the lower spore mass more triA− spores, than expected. Thus, the traits under study depend partly on the cells’ own genotype and partly on the phenotypes, and so genotypes, of other cells: they are both autonomous and non-autonomous. These findings strengthen the parallels between multicellular development and behaviour in social groups. Besides that, they reinforce the point that a trait can be associated with a genotype only in a specified context.

  11. Translocation of an unusual cAMP receptor to the nucleus during development of Dictyostelium discoideum

    Energy Technology Data Exchange (ETDEWEB)

    Kay, C.A.; Noce, T.; Tsang, A.S.

    1987-04-01

    cAMP has been implicated in the control of the expression of developmental genes in Dictyostelium discoideum. To determine the potential role of cAMP receptors as regulators of gene expression, the authors have used immunocytochemical and immunoblotting techniques to reveal the subcellular localization of a cAMP binding protein CABP1. Most of the CABP1 antigen in early developing cells is localized near the cell periphery, with a small amount found in the nucleus. The level of CABP1 in the nucleus increases approx. = 30-fold during development. Moreover, immunofluorescence studies showed that CABP1 can also be detected on the cell surface. Binding of anti-CABP1 to intact cells followed by reaction with /sup 125/I-labeled secondary antibody revealed that the cell-surface CABP1 activity peaks during aggregation and culmination. In addition, several proteins related to CABP1 are found mainly in the nuclear fraction of developing cells. The possible role of these proteins in the regulation of development gene activity is discussed.

  12. Hyperthermic effects on DNA repair of UV-irradiated Dictyostelium discoideum

    Energy Technology Data Exchange (ETDEWEB)

    Ohnishi, T.; Iwata, K.; Hamada, N.; Nozu, K.

    1988-10-01

    DNA repair of Dictyostelium discoideum, was investigated by analysis of heat effects on cell mortality and DNA repair of UV-irradiated amoeboid cells. In a wild-type strain (NC4), an increase in temperature immediately after UV irradiation resulted in increase in cell mortality, though similar treatment before UV irradiation had no such effect. Similar results were obtained in another wild-type strain, HPS83. In NC4, heat treatment after UV irradiation did not inhibit nicking of DNA strands during excision repair processes, but did inhibit rejoining of DNA strand breaks. Removal of thymine-containing pyrimidine dimers from DNA molecules was also depressed by heat treatment after UV irradiation. Heat treatment before UV irradiation had no effect on any stage of the nicking process, dimer excision or rejoining, but a radiation-sensitive mutant (TW8) defective in an incision step of the excision repair process did not show increase in cell mortality in response to heat treatment administered before or after UV. Though optimum temperature for cell growth of the amoebae was 23/sup 0/C, critical temperature for effective enhancement of cell killing was ca. 30/sup 0/C.

  13. Removal of pyrimidine dimers in UV-irradiated spores of Dictyostelium discoideum during germination

    Energy Technology Data Exchange (ETDEWEB)

    Okaichi, K.; Tano, K.; Ohnishi, T.; Nozu, K.

    1985-06-01

    The spores of Dictyostelium discoideum TW-8 (radC) are about twice as sensitive to UV than the parental strain NC-4 spores at a 10% survival level. Ultraviolet irradiation apparently suppressed the emergence of amoebae from swollen TW-8 spores as compared with NC-4 spores, though the conversion of spores into swollen spores was not affected by UV irradiation in either strain. About 85% removal of pyrimidine dimers was detected in UV-irradiated NC-4 spores at 200 J/m/sup 2/ during spore germination for 9 h, but no removal of pyrimidine dimers was detected in TW-8 spores under the same conditions. The removal of pyrimidine dimers from the NC-4 spores began at around 2 h germination when the spores have become swollen. The number of enzyme-sensitive sites (ESS) detected by Micrococcus luteus endonuclease in the DNA of UV-irradiated NC-4 spores also began to decrease at about 2 h into germination. The decrease in ESS, however, was hardly detectable in UV-irradiated TW-8 spores at any step during germination. Cycloheximide inhibited both decrease in the number of pyrimidine dimers, and decrease in the number of ESS of UV-irradiated NC-4 spores. It is suggested that UV-specific endonuclease is newly synthesized in swollen spores of NC-4. (author).

  14. Repair of deoxyribonucleic acid in ultraviolet light-sensitive and -resistant Dictyostelium discoideum strains

    Energy Technology Data Exchange (ETDEWEB)

    Guialis, A.; Deering, R.A.

    1976-07-01

    Some responses of the cellular slime mold Dictyostelium discoideum to ultraviolet light (uv) irradiation were investigated by analyzing two aspects of deoxyribonucleic acid (DNA) excision repair in the vegetative cells: the fate of thymine-containing dimers and the production and rejoining of single-strand breaks. Experiments were done with the parental, radiation-resistant NC-4 strain and with the radiation-sensitive ..gamma..s-13 strain. The majority (greater than 85 percent) of the thymine-containing dimers produced in both strains by an energy fluence of 100 J/m/sup 2/ were removed from the acid-insoluble DNA fraction within the first 3 to 4 h of reincubation in the dark. Moreover, as measured by alkaline sucrose gradients, single-strand breaks appeared in the DNA of both NC-4 and ..gamma..s-13 irradiated cells very rapidly and at low temperatures. This was presumed to be a result of the incision (nicking) step of excision repair as performed by uv-specific endonuclease(s). In NC-4 the time required for dimer excision correlated with the sealing of breaks as well as with the uv-induced division delays. In ..gamma..s-13 the single-strand breaks were closed at a slower rate than in NC-4. However, this was not accompanied by more extensive division delays.

  15. Overexpression of TOR (target of rapamycin) inhibits cell proliferation in Dictyostelium discoideum.

    Science.gov (United States)

    Swer, Pynskhem Bok; Mishra, Himanshu; Lohia, Rakhee; Saran, Shweta

    2016-05-01

    TOR (target of rapamycin) protein kinase acts as a central controller of cell growth and development of an organism. Present study was undertaken to find the expression pattern and role of TOR during growth and development of Dictyostelium discoideum. Failures to generate either knockout and/or knockdown mutants indicate that interference with its levels led to cellular defects. Thus, the effects of TOR (DDB_G0281569) overexpression specifically, cells expressing Dd(Δ211-TOR)-Eyfp mutant was analyzed. Elevated expression of (Δ211-TOR)-Eyfp reduced both cell size and cell proliferation. DdTOR was found to be closer to fungus. mRNA level of TOR was found maximally in the freshly starved/aggregate cells that gradually declined. This was also strengthened by the expression patterns observed by in situ and the analysis of β-galactosidase reporter driven by the putative TOR promoter. The TOR protein was found to be highest at the aggregate stage. The fusion protein, (Δ211-TOR)-Eyfp was localized to the cell membrane, cytosol, and the nucleus. We suggest, DdTOR to be an essential protein and high TOR expression inhibits cell proliferation.

  16. Identification of Proteins Associated with Multilamellar Bodies Produced by Dictyostelium discoideum.

    Directory of Open Access Journals (Sweden)

    Alix M Denoncourt

    Full Text Available Dictyostelium discoideum amoebae produce and secrete multilamellar bodies (MLBs when fed digestible bacteria. The aim of the present study was to elucidate the proteic content of MLBs. The lipid composition of MLBs is mainly amoebal in origin, suggesting that MLB formation is a protozoa-driven process that could play a significant role in amoebal physiology. We identified four major proteins on purified MLBs using mass spectrometry in order to better understand the molecular mechanisms governing MLB formation and, eventually, to elucidate the true function of MLBs. These proteins were SctA, PhoPQ, PonC and a protein containing a cytidine/deoxycytidylate deaminase (CDD zinc-binding region. SctA is a component of pycnosomes, which are membranous materials that are continuously secreted by amoebae. The presence of SctA on MLBs was confirmed by immunofluorescence and Western blotting using a specific anti-SctA antibody. The CDD protein may be one of the proteins recognized by the H36 antibody, which was used as a MLB marker in a previous study. The function of the CDD protein is unknown. Immunofluorescence and flow cytometric analyses confirmed that the H36 antibody is a better marker of MLBs than the anti-SctA antibody. This study is an additional step to elucidate the potential role of MLBs and revealed that only a small set of proteins appeared to be present on MLBs.

  17. Identification of Proteins Associated with Multilamellar Bodies Produced by Dictyostelium discoideum.

    Science.gov (United States)

    Denoncourt, Alix M; Paquet, Valérie E; Sedighi, Ahmadreza; Charette, Steve J

    2016-01-01

    Dictyostelium discoideum amoebae produce and secrete multilamellar bodies (MLBs) when fed digestible bacteria. The aim of the present study was to elucidate the proteic content of MLBs. The lipid composition of MLBs is mainly amoebal in origin, suggesting that MLB formation is a protozoa-driven process that could play a significant role in amoebal physiology. We identified four major proteins on purified MLBs using mass spectrometry in order to better understand the molecular mechanisms governing MLB formation and, eventually, to elucidate the true function of MLBs. These proteins were SctA, PhoPQ, PonC and a protein containing a cytidine/deoxycytidylate deaminase (CDD) zinc-binding region. SctA is a component of pycnosomes, which are membranous materials that are continuously secreted by amoebae. The presence of SctA on MLBs was confirmed by immunofluorescence and Western blotting using a specific anti-SctA antibody. The CDD protein may be one of the proteins recognized by the H36 antibody, which was used as a MLB marker in a previous study. The function of the CDD protein is unknown. Immunofluorescence and flow cytometric analyses confirmed that the H36 antibody is a better marker of MLBs than the anti-SctA antibody. This study is an additional step to elucidate the potential role of MLBs and revealed that only a small set of proteins appeared to be present on MLBs.

  18. Rates of synthesis and degradation of ribosomal ribonucleic acid during differentiation of Dictyostelium discoideum.

    Science.gov (United States)

    Mangiarotti, G; Altruda, F; Lodish, H F

    1981-01-01

    Synthesis of ribosomes and ribosomal ribonucleic acid (RNA) continued during differentiation of Dictyostelium discoideum concurrently with extensive turnover of ribosomes synthesized during both growth and developmental stages. We show here that the rate of synthesis of 26S and 17S ribosomal RNA during differentiation was less than 15% of that in growing cells, and by the time of sorocarp formation only about 25% of the cellular ribosomes had been synthesized during differentiation. Ribosomes synthesized during growth and differentiation were utilized in messenger RNA translation to the same extent; about 50% of each class were on polyribosomes. Ribosome degradation is apparently an all-or-nothing process, since virtually all 80S monosomes present in developing cells could be incorporated into polysomes when growth conditions were restored. By several criteria, ribosomes synthesized during growth and differentiation were functionally indistinguishable. Our data, together with previously published information on changes in the messenger RNA population during differentiation, indicate that synthesis of new ribosomes is not necessary for translation of developmentally regulated messenger RNA. We also establish that the overall rate of messenger RNA synthesis during differentiation is less than 15% of that in growing cells.

  19. Regulation of gene expression in Dictyostelium discoideum cells exposed to immobilized carbohydrates.

    Science.gov (United States)

    Bozzaro, S; Perlo, C; Ceccarelli, A; Mangiarotti, G

    1984-01-01

    When amoebae of Dictyostelium discoideum develop on gels of polyacrylamide that are derivatized with glucosides, they become capable of aggregation at the same time as cells not exposed to glucosides. However, the aggregation centers and streams of adherent cells formed on immobilized glucosides suddenly disintegrate. The cells repeatedly re-aggregate, but never form tight aggregates as they do on other substrata. Tight aggregates formed in the absence of glucosides disperse after their transfer to glucoside gels, and the cells undergo aggregation-disaggregation cycles. The formation of tight aggregates is correlated with the expression of specific post-aggregative poly(A) RNAs. These RNAs are not expressed in cells developing on glucoside gels, and the dispersal of tight aggregates on such gels is accompanied by the almost complete loss of these RNAs. A developmentally regulated membrane glycoprotein called contact site A, which is a marker of aggregation-competent cells, is normally expressed on glucoside gels. Cyclic AMP is also produced, indicating that the strong increase of adenylate cyclase activity during the preaggregation phase is not affected. In conclusion, cell contact with immobilized glucosides specifically inhibits postaggregative gene expression and arrests development at the aggregation stage.

  20. Microtubules are Essential for Mitochondrial Dynamics-Fission, Fusion, and Motility- in Dictyostelium discoideum.

    Directory of Open Access Journals (Sweden)

    Laken C. Woods

    2016-03-01

    Full Text Available Mitochondrial function is dependent upon mitochondrial structure which is in turn dependent upon mitochondrial dynamics, including fission, fusion, and motility. Here we examined the relationship between mitochondrial dynamics and the cytoskeleton in Dictyostelium discoideum. Using time-lapse analysis, we quantified mitochondrial fission, fusion, and motility in the presence of cytoskeleton disrupting pharmaceuticals and the absence of the potential mitochondria-cytoskeleton linker protein, CluA. Our results indicate that microtubules are essential for mitochondrial movement, as well as fission and fusion; actin plays a less significant role, perhaps selecting the mitochondria for transport. We also suggest that CluA is not a linker protein but plays an unidentified role in mitochondrial fission and fusion. The significance of our work is to gain further insight into the role the cytoskeleton plays in mitochondrial dynamics and function. By better understanding these processes we can better appreciate the underlying mitochondrial contributions to many neurological disorders characterized by altered mitochondrial dynamics, structure, and/or function.

  1. Actin-Interacting Protein 1 Contributes to Intranuclear Rod Assembly in Dictyostelium discoideum

    Science.gov (United States)

    Ishikawa-Ankerhold, Hellen C.; Daszkiewicz, Wioleta; Schleicher, Michael; Müller-Taubenberger, Annette

    2017-01-01

    Intranuclear rods are aggregates consisting of actin and cofilin that are formed in the nucleus in consequence of chemical or mechanical stress conditions. The formation of rods is implicated in a variety of pathological conditions, such as certain myopathies and some neurological disorders. It is still not well understood what exactly triggers the formation of intranuclear rods, whether other proteins are involved, and what the underlying mechanisms of rod assembly or disassembly are. In this study, Dictyostelium discoideum was used to examine appearance, stages of assembly, composition, stability, and dismantling of rods. Our data show that intranuclear rods, in addition to actin and cofilin, are composed of a distinct set of other proteins comprising actin-interacting protein 1 (Aip1), coronin (CorA), filactin (Fia), and the 34 kDa actin-bundling protein B (AbpB). A finely tuned spatio-temporal pattern of protein recruitment was found during formation of rods. Aip1 is important for the final state of rod compaction indicating that Aip1 plays a major role in shaping the intranuclear rods. In the absence of both Aip1 and CorA, rods are not formed in the nucleus, suggesting that a sufficient supply of monomeric actin is a prerequisite for rod formation. PMID:28074884

  2. Yersinia outer protein YopE affects the actin cytoskeleton in Dictyostelium discoideum through targeting of multiple Rho family GTPases

    LENUS (Irish Health Repository)

    Vlahou, Georgia

    2009-07-14

    Abstract Background All human pathogenic Yersinia species share a virulence-associated type III secretion system that translocates Yersinia effector proteins into host cells to counteract infection-induced signaling responses and prevent phagocytosis. Dictyostelium discoideum has been recently used to study the effects of bacterial virulence factors produced by internalized pathogens. In this study we explored the potential of Dictyostelium as model organism for analyzing the effects of ectopically expressed Yersinia outer proteins (Yops). Results The Yersinia pseudotuberculosis virulence factors YopE, YopH, YopM and YopJ were expressed de novo within Dictyostelium and their effects on growth in axenic medium and on bacterial lawns were analyzed. No severe effect was observed for YopH, YopJ and YopM, but expression of YopE, which is a GTPase activating protein for Rho GTPases, was found to be highly detrimental. GFP-tagged YopE expressing cells had less conspicuous cortical actin accumulation and decreased amounts of F-actin. The actin polymerization response upon cAMP stimulation was impaired, although chemotaxis was unaffected. YopE also caused reduced uptake of yeast particles. These alterations are probably due to impaired Rac1 activation. We also found that YopE predominantly associates with intracellular membranes including the Golgi apparatus and inhibits the function of moderately overexpressed RacH. Conclusion The phenotype elicited by YopE in Dictyostelium can be explained, at least in part, by inactivation of one or more Rho family GTPases. It further demonstrates that the social amoeba Dictyostelium discoideum can be used as an efficient and easy-to-handle model organism in order to analyze the function of a translocated GAP protein of a human pathogen.

  3. Transcriptional down-regulation and rRNA cleavage in Dictyostelium discoideum mitochondria during Legionella pneumophila infection.

    Directory of Open Access Journals (Sweden)

    Chenyu Zhang

    Full Text Available Bacterial pathogens employ a variety of survival strategies when they invade eukaryotic cells. The amoeba Dictyostelium discoideum is used as a model host to study the pathogenic mechanisms that Legionella pneumophila, the causative agent of Legionnaire's disease, uses to kill eukaryotic cells. Here we show that the infection of D. discoideum by L. pneumophila results in a decrease in mitochondrial messenger RNAs, beginning more than 8 hours prior to detectable host cell death. These changes can be mimicked by hydrogen peroxide treatment, but not by other cytotoxic agents. The mitochondrial large subunit ribosomal RNA (LSU rRNA is also cleaved at three specific sites during the course of infection. Two LSU rRNA fragments appear first, followed by smaller fragments produced by additional cleavage events. The initial LSU rRNA cleavage site is predicted to be on the surface of the large subunit of the mitochondrial ribosome, while two secondary sites map to the predicted interface with the small subunit. No LSU rRNA cleavage was observed after exposure of D. discoideum to hydrogen peroxide, or other cytotoxic chemicals that kill cells in a variety of ways. Functional L. pneumophila type II and type IV secretion systems are required for the cleavage, establishing a correlation between the pathogenesis of L. pneumophila and D. discoideum LSU rRNA destruction. LSU rRNA cleavage was not observed in L. pneumophila infections of Acanthamoeba castellanii or human U937 cells, suggesting that L. pneumophila uses distinct mechanisms to interrupt metabolism in different hosts. Thus, L. pneumophila infection of D. discoideum results in dramatic decrease of mitochondrial RNAs, and in the specific cleavage of mitochondrial rRNA. The predicted location of the cleavage sites on the mitochondrial ribosome suggests that rRNA destruction is initiated by a specific sequence of events. These findings suggest that L. pneumophila specifically disrupts mitochondrial

  4. Ca2+ regulation in the absence of the iplA gene product in Dictyostelium discoideum

    Directory of Open Access Journals (Sweden)

    Happle Kathrin

    2005-03-01

    Full Text Available Abstract Background Stimulation of Dictyostelium discoideum with cAMP evokes an elevation of the cytosolic free Ca2+ concentration ([Ca2+]i. The [Ca2+]i-change is composed of liberation of stored Ca2+ and extracellular Ca2+-entry. The significance of the [Ca2+]i-transient for chemotaxis is under debate. Abolition of chemotactic orientation and migration by Ca2+-buffers in the cytosol indicates that a [Ca2+]i-increase is required for chemotaxis. Yet, the iplA- mutant disrupted in a gene bearing similarity to IP3-receptors of higher eukaryotes aggregates despite the absence of a cAMP-induced [Ca2+]i-transient which favours the view that [Ca2+]i-changes are insignificant for chemotaxis. Results We investigated Ca2+-fluxes and the effect of their disturbance on chemotaxis and development of iplA- cells. Differentiation was altered as compared to wild type amoebae and sensitive towards manipulation of the level of stored Ca2+. Chemotaxis was impaired when [Ca2+]i-transients were suppressed by the presence of a Ca2+-chelator in the cytosol of the cells. Analysis of ion fluxes revealed that capacitative Ca2+-entry was fully operative in the mutant. In suspensions of intact and permeabilized cells cAMP elicited extracellular Ca2+-influx and liberation of stored Ca2+, respectively, yet to a lesser extent than in wild type. In suspensions of partially purified storage vesicles ATP-induced Ca2+-uptake and Ca2+-release activated by fatty acids or Ca2+-ATPase inhibitors were similar to wild type. Mn2+-quenching of fura2 fluorescence allows to study Ca2+-influx indirectly and revealed that the responsiveness of mutant cells was shifted to higher concentrations: roughly 100 times more Mn2+ was necessary to observe agonist-induced Mn2+-influx. cAMP evoked a [Ca2+]i-elevation when stores were strongly loaded with Ca2+, again with a similar shift in sensitivity in the mutant. In addition, basal [Ca2+]i was significantly lower in iplA- than in wild type amoebae

  5. A membrane cytoskeleton from Dictyostelium discoideum. I. Identification and partial characterization of an actin-binding activity

    Energy Technology Data Exchange (ETDEWEB)

    Luna, E.J.; Fowler, V.M.; Swanson, J.; Branton, D.; Taylor, D.L.

    1981-02-01

    Dictyostelium discoideum plasma membranes isolated by each of three procedures bind F-actin. The interactions between these membranes and actin are examined by a novel application of falling ball viscometry. Treating the membranes as multivalent actin-binding particles analogous to divalent actin-gelatin factors, large increases in viscosity (actin-cross-linking) were observed when membranes depleted of actin and myosin are incubated with rabbit skeletal muscle F-actin. Pre-extraction of peripheral membrane proteins with chaotropes or the inclusion of Triton X-100 during the assay does not appreciably diminish this actin cross-linking activity. Lipid vesicles, heat-denatured membranes, proteolyzed membranes, or membranes containing endogenous actin show minimal actin cross-linking activity. Heat-denatured, but not proteolyzed, membranes regain activity when assayed in the presence of Triton X-100. Thus, integral membrane proteins appear to be responsible for some or all of the actin cross-linking activity of D. discoideum membranes. In the absence of MgATP, Triton X-100 extraction of isolated D. discoideum membranes results in a Triton-insoluble residue composed of actin, myosin, and associated membrane proteins. The inclusion of MgATP before and during Triton extraction greatly diminishes the amount of protein in the Triton-insoluble residue without appreciably altering its composition. Our results suggest the existence of a protein complex stabilized by actin and/or myosin (membrane cytoskeleton) associated with the D. discoideum plasma membrane.

  6. Characterization of PEBBLEs as a Tool for Real-Time Measurement of Dictyostelium discoideum Endosomal pH

    Directory of Open Access Journals (Sweden)

    Everett Moding

    2009-01-01

    Full Text Available The measurement of intracellular ion concentration change is important for understanding the cellular mechanisms for communication. Recently developed nanosensors, (Photonic Explorers for Biomedical use with Biologically Localized Embedding PEBBLEs, have a number of advantages for measuring ions in cells over established methods using microelectrodes, unbound fluorescent dyes, or NMR. PEBBLE sensors have been shown to work in principle for measuring dynamic ion changes, but few in vivo applications have been demonstrated. We modified the protocol for the fabrication of pH sensing PEBBLEs and developed a protocol for the utilization of these sensors for the monitoring of dynamic pH changes in the endosomes of slime mold Dictyostelium discoideum (D. discoideum. Oregon Green 514-CdSe Quantum Dot PEBBLEs were used to measure real-time pH inside D. discoideum endosomes during cAMP stimulation. Endosomal pH was shown to decrease during cAMP signaling, demonstrating a movement of protons into the endosomes of D. discoideum amoebae.

  7. Curcumin inhibits development and cell adhesion in Dictyostelium discoideum: Implications for YakA signaling and GST enzyme function

    Energy Technology Data Exchange (ETDEWEB)

    Garige, Mamatha; Walters, Eric, E-mail: ewalters@howard.edu

    2015-11-13

    The molecular basis for nutraceutical properties of the polyphenol curcumin (Curcuma longa, Turmeric) is complex, affecting multiple factors that regulate cell signaling and homeostasis. Here, we report the effect of curcumin on cellular and developmental mechanisms in the eukaryotic model, Dictyostelium discoideum. Dictyostelium proliferation was inhibited in the presence of curcumin, which also suppressed the prestarvation marker, discoidin I, members of the yakA-mediated developmental signaling pathway, and expression of the extracellular matrix/cell adhesion proteins (DdCAD and csA). This resulted in delayed chemotaxis, adhesion, and development of the organism. In contrast to the inhibitory effects on developmental genes, curcumin induced gstA gene expression, overall GST activity, and generated production of reactive oxygen species. These studies expand our knowledge of developmental and biochemical signaling influenced by curcumin, and lends greater consideration of GST enzyme function in eukaryotic cell signaling, development, and differentiation.

  8. Effects of time-variant extremely low-frequency (ELF) electromagnetic fields (EMF) on cholinesterase activity in Dictyostelium discoideum (Protista).

    Science.gov (United States)

    Amaroli, Andrea; Trielli, Francesca; Bianco, Bruno; Giordano, Stefano; Moggia, Elsa; Corrado, Maria U Delmonte

    2005-12-15

    Recently, we detected propionylcholinesterase (PrChE) activity in single-cell amoebae of Dictyostelium discoideum using cytochemical, electrophoretic, and spectrophotometric methods. The involvement of this enzyme activity in cell-cell and cell-environment interactions was suggested. In this work, we found that exposure of single-cell amoebae to an extremely low-frequency electromagnetic fields (ELF-EMF) of 300 microT, 50 Hz, from 1 h up to 48 h at 21 +/- 1 degrees C affected PrChE activity.

  9. Characterization of a 1,4-{beta}-D-glucan synthase from Dictyostelium discoideum. Progress report, May 1990--January 1992

    Energy Technology Data Exchange (ETDEWEB)

    Blanton, R.L.

    1992-01-15

    Various aspects of research concerning Dictyostelium discoideum are presented. The initial focus of this project was upon: the characterization of potential probes for the cellulose synthase (antibody and nucleic acid), the determination of the cultural induction conditions of cellulose synthesis, the solubilization of the enzyme activity, the development of a non-inhibitory disruption buffer, the generation and isolation of mutant strains deficient in cellulose synthesis, and the development of the capability to determine the degree of polymerization of the in vitro product. I have briefly summarized our most significant findings with only selected data sets being shown in this report in the interest of brevity.

  10. Enhancement of ultraviolet or N-methyl-N'-nitro-N-nitrosoguanidine sensitivity of Dictyostelium discoideum by 3-aminobenzamide

    Energy Technology Data Exchange (ETDEWEB)

    Ohnishi, T.; Eimoto, H.; Okaichi, K. (Nara Medical Univ., Kashihara (Japan))

    1982-04-01

    The amoeboid cells of Dictyostelium discoideum NC-4 possess a 3-aminobenzamide(3-ABA)-sensitive repair mechanism for DNA damages induced by UV-irradiation or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-treatment. The effect of 3-ABA on each step of excision repair in the UV-irradiated cells was studied. Although the nicking of DNA-strand and the excision of pyrimidine dimers are insensitive to 3-ABA, the rejoining of DNA strand-breaks is sensitive. The frequency of mutation induced by UV-irradiation or MNNG-treatment is depressed by 3-ABA. The mechanisms of repair inhibition by 3-ABA are discussed.

  11. Scanning the available Dictyostelium discoideum proteome for O-linked GlcNAc glycosylation sitesusing neural networks

    DEFF Research Database (Denmark)

    Gupta, Ramneek; Jung, Eva; Gooley, Andrew A

    1999-01-01

    found to be situated only at even positions with respect to each other, indicating that these may be located within beta-strands. The method has been used for a rapid and ranked scan of the fraction of the Dictyostelium proteome available in public databases, remarkably 25-30% of which were predicted......-glycosylations in D. discoideum proteins has been made available through the WWW at http://www.cbs.dtu.dk/services/DictyOGlyc/ and via E-mail to DictyOGlyc@cbs.dtu.dk....

  12. Dictyostelium discoideum RabS and Rab2 colocalize with the Golgi and contractile vacuole system and regulate osmoregulation

    Indian Academy of Sciences (India)

    Katherine Maringer; Azure Yarbrough; Sunder Sims-Lucas; Entsar Saheb; Sanaa Jawed; John Bush

    2016-06-01

    Small-molecular-weight GTPase Rab2 has been shown to be a resident of pre-Golgi intermediates and is required for protein transport from the ER to the Golgi complex; however, Rab2 has yet to be characterized in Dictyostelium discoideum. DdRabS is a Dictyostelium Rab that is 80% homologous to DdRab1 which is required for protein transport between the ER and Golgi. Expression of GFP-tagged DdRab2 and DdRabS proteins showed localization to Golgi membranes and to the contractile vacuole system (CV) in Dictyostelium. Microscopic imaging indicates that the DdRab2 and DdRabS proteins localize at, and are essential for, the proper structure of Golgi membranes and the CV system. Dominant negative (DN) forms show fractionation of Golgi membranes, supporting their role in the structure and function of it. DdRab2 and DdRabS proteins, and their dominant negative and constitutively active (CA) forms, affect osmoregulation of the cells, possibly by the influx and discharge of fluids, which suggests a role in the function of the CV system. This is the first evidence of GTPases being localized to both Golgi membranes and the CV system in Dictyostelium.

  13. Regulation of Spatiotemporal Patterns by Biological Variability: General Principles and Applications to Dictyostelium discoideum.

    Directory of Open Access Journals (Sweden)

    Miriam Grace

    2015-11-01

    Full Text Available Spatiotemporal patterns often emerge from local interactions in a self-organizing fashion. In biology, the resulting patterns are also subject to the influence of the systematic differences between the system's constituents (biological variability. This regulation of spatiotemporal patterns by biological variability is the topic of our review. We discuss several examples of correlations between cell properties and the self-organized spatiotemporal patterns, together with their relevance for biology. Our guiding, illustrative example will be spiral waves of cAMP in a colony of Dictyostelium discoideum cells. Analogous processes take place in diverse situations (such as cardiac tissue, where spiral waves occur in potentially fatal ventricular fibrillation so a deeper understanding of this additional layer of self-organized pattern formation would be beneficial to a wide range of applications. One of the most striking differences between pattern-forming systems in physics or chemistry and those in biology is the potential importance of variability. In the former, system components are essentially identical with random fluctuations determining the details of the self-organization process and the resulting patterns. In biology, due to variability, the properties of potentially very few cells can have a driving influence on the resulting asymptotic collective state of the colony. Variability is one means of implementing a few-element control on the collective mode. Regulatory architectures, parameters of signaling cascades, and properties of structure formation processes can be "reverse-engineered" from observed spatiotemporal patterns, as different types of regulation and forms of interactions between the constituents can lead to markedly different correlations. The power of this biology-inspired view of pattern formation lies in building a bridge between two scales: the patterns as a collective state of a very large number of cells on the one hand

  14. Biological Activity of the Alternative Promoters of the Dictyostelium discoideum Adenylyl Cyclase A Gene.

    Science.gov (United States)

    Rodriguez-Centeno, Javier; Sastre, Leandro

    2016-01-01

    Amoebae of the Dictyostelium discoideum species form multicellular fruiting bodies upon starvation. Cyclic adenosine monophosphate (cAMP) is used as intercellular signalling molecule in cell-aggregation, cell differentiation and morphogenesis. This molecule is synthesized by three adenylyl cyclases, one of which, ACA, is required for cell aggregation. The gene coding for ACA (acaA) is transcribed from three different promoters that are active at different developmental stages. Promoter 1 is active during cell-aggregation, promoters 2 and 3 are active in prespore and prestalk tip cells at subsequent developmental stages. The biological relevance of acaA expression from each of the promoters has been studied in this article. The acaA gene was expressed in acaA-mutant cells, that do not aggregate, under control of each of the three acaA promoters. acaA expression under promoter 1 control induced cell aggregation although subsequent development was delayed, very small fruiting bodies were formed and cell differentiation genes were expressed at very low levels. Promoter 2-driven acaA expression induced the formation of small aggregates and small fruiting bodies were formed at the same time as in wild-type strains and differentiation genes were also expressed at lower levels. Expression of acaA from promoter 3 induced aggregates and fruiting bodies formation and their size and the expression of differentiation genes were more similar to that of wild-type cells. Expression of acaA from promoters 1 and 2 in AX4 cells also produced smaller structures. In conclusion, the expression of acaA under control of the aggregation-specific Promoter 1 is able to induce cell aggregation in acaA-mutant strains. Expression from promoters 2 and 3 also recovered aggregation and development although promoter 3 induced a more complete recovery of fruiting body formation.

  15. Cell behavior in Dictyostelium discoideum: preaggregation response to localized cyclic AMP pulses.

    Science.gov (United States)

    Futrelle, R P; Traut, J; McKee, W G

    1982-03-01

    The motion of cells in the aggregation phase of Dictyostelium discoideum development is complex. To probe its mechanisms we applied precisely timed (+/- 1 s) and positioned (+/-2 micrometers) pulses of cyclic AMP to fields of cells of moderate density using a micropipette. We recorded cell behavior by time lapse microcinematography and extracted cell motion data from the film with our Galatea computer system. Analysis of these data reveals: (a) Chemotaxis lasts only about as long as the cyclic AMP signal; in particular, brief pulses (approximately 5 s) do not induce chemotaxis. (b) Chemotactic competence increases gradually from within an hour after the initiation of development (starvation) to full competence at approximately 15 h when aggregation begins under our conditions. (c) Cell motion reverses rapidly (within 20 s) when the external gradient is reversed. There is no refractory period for motion. We present a new description of the process of aggregation consistent with our result and other recent findings. (d) The behavioral response to cyclic AMP includes a phenomenon we call "cringing." In a prototypical cringe the cell speed drops within 3 s after a brief cyclic AMP stimulus, and the cell stops and rounds and then resumes motion after 25 s. (e) The development of the speed response in cringing as the cells age closely parallels the development of the cyclic AMP-induced light-scattering response of cells in suspension. (f) Cringing occurs in natural populations during weak oriented movement. The computerized analysis of cell behavior proves to be a powerful technique which can reveal significant phenomena that are not apparent to the eye even after repeated examination of the film.

  16. Emerging models for DNA repair: Dictyostelium discoideum as a model for nonhomologous end-joining.

    Science.gov (United States)

    Pears, Catherine J; Lakin, Nicholas D

    2014-05-01

    DNA double strand breaks (DSBs) are a particularly cytotoxic variety of DNA lesion that can be repaired by homologous recombination (HR) or nonhomologous end-joining (NHEJ). HR utilises sequences homologous to the damage DNA template to facilitate repair. In contrast, NHEJ does not require homologous sequences for repair but instead functions by directly re-joining DNA ends. These pathways are critical to resolve DSBs generated intentionally during processes such as meiotic and site-specific recombination. However, they are also utilised to resolve potentially pathological DSBs generated by mutagens and errors during DNA replication. The importance of DSB repair is underscored by the findings that defects in these pathways results in chromosome instability that contributes to a variety of disease states including malignancy. The general principles of NHEJ are conserved in eukaryotes. As such, relatively simple model organisms have been instrumental in identifying components of these pathways and providing a mechanistic understanding of repair that has subsequently been applied to vertebrates. However, certain components of the NHEJ pathway are absent or show limited conservation in the most commonly used invertebrate models exploited to study DNA repair. Recently, however, it has become apparent that vertebrate DNA repair pathway components, including those involved in NHEJ, are unusually conserved in the amoeba Dictyostelium discoideum. Traditionally, this genetically tractable organism has been exploited to study the molecular basis of cell type specification, cell motility and chemotaxis. Here we discuss the use of this organism as an additional model to study DNA repair, with specific reference to NHEJ. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Relevant Genes Linked to Virulence Are Required for Salmonella Typhimurium to Survive Intracellularly in the Social Amoeba Dictyostelium discoideum.

    Science.gov (United States)

    Riquelme, Sebastián; Varas, Macarena; Valenzuela, Camila; Velozo, Paula; Chahin, Nicolás; Aguilera, Paulina; Sabag, Andrea; Labra, Bayron; Álvarez, Sergio A; Chávez, Francisco P; Santiviago, Carlos A

    2016-01-01

    The social amoeba Dictyostelium discoideum has proven to be a useful model for studying relevant aspects of the host-pathogen interaction. In this work, D. discoideum was used as a model to study the ability of Salmonella Typhimurium to survive in amoebae and to evaluate the contribution of selected genes in this process. To do this, we performed infection assays using axenic cultures of D. discoideum co-cultured with wild-type S. Typhimurium and/or defined mutant strains. Our results confirmed that wild-type S. Typhimurium is able to survive intracellularly in D. discoideum. In contrast, mutants ΔaroA and ΔwaaL are defective in intracellular survival in this amoeba. Next, we included in our study a group of mutants in genes directly linked to Salmonella virulence. Of note, mutants ΔinvA, ΔssaD, ΔclpV, and ΔphoPQ also showed an impaired ability to survive intracellularly in D. discoideum. This indicates that S. Typhimurium requires a functional biosynthetic pathway of aromatic compounds, a lipopolysaccharide containing a complete O-antigen, the type III secretion systems (T3SS) encoded in SPI-1 and SPI-2, the type VI secretion system (T6SS) encoded in SPI-6 and PhoP/PhoQ two-component system to survive in D. discoideum. To our knowledge, this is the first report on the requirement of O-antigen and T6SS in the survival of Salmonella within amoebae. In addition, mutants ΔinvA and ΔssaD were internalized in higher numbers than the wild-type strain during competitive infections, suggesting that S. Typhimurium requires the T3SS encoded in SPI-1 and SPI-2 to evade phagocytosis by D. discoideum. Altogether, these results indicate that S. Typhimurium exploits a common set of genes and molecular mechanisms to survive within amoeba and animal host cells. The use of D. discoideum as a model for host-pathogen interactions will allow us to discover the gene repertoire used by Salmonella to survive inside the amoeba and to study the cellular processes that are affected

  18. Whole genome sequencing of mutation accumulation lines reveals a low mutation rate in the social amoeba Dictyostelium discoideum.

    Directory of Open Access Journals (Sweden)

    Gerda Saxer

    Full Text Available Spontaneous mutations play a central role in evolution. Despite their importance, mutation rates are some of the most elusive parameters to measure in evolutionary biology. The combination of mutation accumulation (MA experiments and whole-genome sequencing now makes it possible to estimate mutation rates by directly observing new mutations at the molecular level across the whole genome. We performed an MA experiment with the social amoeba Dictyostelium discoideum and sequenced the genomes of three randomly chosen lines using high-throughput sequencing to estimate the spontaneous mutation rate in this model organism. The mitochondrial mutation rate of 6.76×10(-9, with a Poisson confidence interval of 4.1×10(-9 - 9.5×10(-9, per nucleotide per generation is slightly lower than estimates for other taxa. The mutation rate estimate for the nuclear DNA of 2.9×10(-11, with a Poisson confidence interval ranging from 7.4×10(-13 to 1.6×10(-10, is the lowest reported for any eukaryote. These results are consistent with low microsatellite mutation rates previously observed in D. discoideum and low levels of genetic variation observed in wild D. discoideum populations. In addition, D. discoideum has been shown to be quite resistant to DNA damage, which suggests an efficient DNA-repair mechanism that could be an adaptation to life in soil and frequent exposure to intracellular and extracellular mutagenic compounds. The social aspect of the life cycle of D. discoideum and a large portion of the genome under relaxed selection during vegetative growth could also select for a low mutation rate. This hypothesis is supported by a significantly lower mutation rate per cell division in multicellular eukaryotes compared with unicellular eukaryotes.

  19. Developmentally regulated promoters from Dictyostelium discoideum as molecular markers for testing potential teratogens.

    Science.gov (United States)

    Tillner, J; Winckler, T; Dingermann, T

    1996-11-01

    Already very early in the course of the development of new pharmaceutically relevant drugs toxicological tests are most important. In addition to acute and chronic toxicity the estimation of the teratogenic potential is rather crucial. We have recently shown that the eukaryotic microorganism Dictyostellium discoideum is a useful organism to test the cytotoxicity of chemical compounds. Since D. discoideum is competent of undergoing both vegetative growth and development, further investigations were aimed to establish a D. discoideum-based test system which could predict possible interference of drugs with developmental programs. We developed a method which allows to detect and to quantify effects of possible teratogens on D. discoideum development. This method is based on different transgenic D. discoideum strains, each carrying a bacterial lacZ gene under the control of a distinct developmentally regulated D. discoideum promoter. Here we describe the effects of the known teratogenic compound valproic acid (VPA) on this system.

  20. Specificity of the Cyclic GMP-Binding Activity and of a Cyclic GMP-Dependent Cyclic GMP Phosphodiesterase in Dictyostelium discoideum

    NARCIS (Netherlands)

    Haastert, Peter J.M. van; Walsum, Hans van; Meer, Rob C. van der; Bulgakov, Roman; Konijn, Theo M.

    1982-01-01

    The nucleotide specificity of the cyclic GMP-binding activity in a homogenate of Dictyostelium discoideum was determined by competition of cyclic GMP derivatives with [8-3H] cyclic GMP for the binding sites. The results indicate that cyclic GMP is bound to the binding proteins by hydrogen bonds at N

  1. Activation of a pertussis-toxin-sensitive guanine-nucleotide-binding regulatory protein during desensitization of Dictyostelium discoideum cells to chemotactic signals

    NARCIS (Netherlands)

    Snaar-Jagalska, B. Ewa; Es, Saskia van; Kesbeke, Fanja; Haastert, Peter J.M. van

    1991-01-01

    The chemoattractant cAMP induces the activation of adenylate cyclase in Dictyostelium discoideum. Upon prolonged incubation with cAMP, cells become desensitized via two distinct processes: a decrease in the number of available cAMP-binding sites (down regulation) and modification of the receptor (pr

  2. Differential Effects of Temperature on cAMP-induced Excitation, Adaptation, and Deadaptation of Adenylate and Guanylate Cyclase in Dictyostelium discoideum

    NARCIS (Netherlands)

    Haastert, Peter J.M. van

    1987-01-01

    Extracellular cAMP induces excitation of adenylate and guanylate cyclase in Dictyostelium discoideum. Continuous stimulation with cAMP leads to adaptation, while cells deadapt upon removal of the cAMP stimulus. Excitation of guanylate cyclase by cAMP has a lag time of ~1 s; excitation of adenylate c

  3. Cyclic nucleotide specificity of the activator and catalytic sites of a cGMP-stimulated cGMP phosphodiesterase from Dictyostelium discoideum

    NARCIS (Netherlands)

    Kesbeke, Fanja; Baraniak, Janina; Bulgakov, Roman; Jastorff, Bernd; Morr, Michael; Petridis, Georg; Stec, Wojciech J.; Seela, Frank; Haastert, Peter J.M. van

    1985-01-01

    The cellular slime mold Dictyostelium discoideum has an intracellular phosphodiesterase which specifically hydrolyzes cGMP. The enzyme is activated by low cGMP concentrations, and is involved in the reduction of chemoattractant-mediated elevations of cGMP levels. The interaction of 20 cGMP derivativ

  4. Identification of a cyclase-associated protein (CAP) homologue in Dictyostelium discoideum and characterization of its interaction with actin.

    Science.gov (United States)

    Gottwald, U; Brokamp, R; Karakesisoglou, I; Schleicher, M; Noegel, A A

    1996-02-01

    In search for novel actin binding proteins in Dictyostelium discoideum we have isolated a cDNA clone coding for a protein of approximately 50 kDa that is highly homologous to the class of adenylyl cyclase-associated proteins (CAP). In Saccharomyces cerevisiae the amino-terminal part of CAP is involved in the regulation of the adenylyl cyclase whereas the loss of the carboxyl-terminal domain results in morphological and nutritional defects. To study the interaction of Dictyostelium CAP with actin, the complete protein and its amino-terminal and carboxyl-terminal domains were expressed in Escherichia coli and used in actin binding assays. CAP sequestered actin in a Ca2+ independent way. This activity was localized to the carboxyl-terminal domain. CAP and its carboxyl-terminal domain led to a fluorescence enhancement of pyrene-labeled G-actin up to 50% indicating a direct interaction, whereas the amino-terminal domain did not enhance. In polymerization as well as in viscometric assays the ability of the carboxyl-terminal domain to sequester actin and to prevent F-actin formation was approximately two times higher than that of intact CAP. The sequestering activity of full length CAP could be inhibited by phosphatidylinositol 4,5-bisphosphate (PIP2), whereas the activity of the carboxyl-terminal domain alone was not influenced, suggesting that the amino-terminal half of the protein is required for the PIP2 modulation of the CAP function. In profilin-minus cells the CAP concentration is increased by approximately 73%, indicating that CAP may compensate some profilin functions in vivo. In migrating D. discoideum cells CAP was enriched at anterior and posterior plasma membrane regions. Only a weak staining of the cytoplasm was observed. In chemotactically stimulated cells the protein was very prominent in leading fronts. The data suggest an involvement of D. discoideum CAP in microfilament reorganization near the plasma membrane in a PIP2-regulated manner.

  5. Structural and functional studies of a family of Dictyostelium discoideum developmentally regulated, prestalk genes coding for small proteins

    Directory of Open Access Journals (Sweden)

    Escalante Ricardo

    2008-01-01

    Full Text Available Abstract Background The social amoeba Dictyostelium discoideum executes a multicellular development program upon starvation. This morphogenetic process requires the differential regulation of a large number of genes and is coordinated by extracellular signals. The MADS-box transcription factor SrfA is required for several stages of development, including slug migration and spore terminal differentiation. Results Subtractive hybridization allowed the isolation of a gene, sigN (SrfA-induced gene N, that was dependent on the transcription factor SrfA for expression at the slug stage of development. Homology searches detected the existence of a large family of sigN-related genes in the Dictyostelium discoideum genome. The 13 most similar genes are grouped in two regions of chromosome 2 and have been named Group1 and Group2 sigN genes. The putative encoded proteins are 87–89 amino acids long. All these genes have a similar structure, composed of a first exon containing a 13 nucleotides long open reading frame and a second exon comprising the remaining of the putative coding region. The expression of these genes is induced at10 hours of development. Analyses of their promoter regions indicate that these genes are expressed in the prestalk region of developing structures. The addition of antibodies raised against SigN Group 2 proteins induced disintegration of multi-cellular structures at the mound stage of development. Conclusion A large family of genes coding for small proteins has been identified in D. discoideum. Two groups of very similar genes from this family have been shown to be specifically expressed in prestalk cells during development. Functional studies using antibodies raised against Group 2 SigN proteins indicate that these genes could play a role during multicellular development.

  6. Characterization of a third ras gene, rasB, that is expressed throughout the growth and development of Dictyostelium discoideum.

    Science.gov (United States)

    Daniel, J; Spiegelman, G B; Weeks, G

    1993-04-01

    Previous reports have indicated that the cellular slime mold Dictyostelium discoideum possesses two ras genes (rasG and rasD) and one rap gene (rap1). All three genes are developmentally regulated, with each showing a different pattern of transcription during the Dictyostelium life cycle. To establish whether there are additional ras or rap genes in Dictyostelium, we used degenerate oligonucleotide primers to the highly conserved GTP-binding domains and both ras- and rap-unique sequences to amplify products from cDNA using the polymerase chain reaction (PCR). No additional rap genes were amplified, but a fragment whose nucleotide sequence predicted a novel ras gene was isolated. Using this PCR product as a probe, a full-length cDNA clone was isolated and sequenced. Its deduced amino acid sequence predicted a 197 amino acid protein that is 71% and 68% identical to RasG and RasD respectively. The new ras gene contains the conserved Ras-specific effector domain, the conserved binding site for the Ras-specific Y13-259 monoclonal antibody, and shows greater sequence similarity to the human H-Ras protein than to any other mammalian Ras protein. In view of this high level of identity to the ras gene subfamily, we have designated this gene rasB. Northern blot analysis has shown that rasB is developmentally regulated with maximum levels of a single 950-bp message detected during vegetative growth and the first 8 h of development.

  7. Identification of a high-affinity Ca sup 2+ pump associated with endocytotic vesicles in Dictyostelium discoideum

    Energy Technology Data Exchange (ETDEWEB)

    Milne, J.L.; Coukell, M.B. (York Univ., North York, Ontario (Canada))

    1989-11-01

    In the cellular slime mold Dictyostelium discoideum, changes in free cytosolic Ca{sup 2+} are thought to regulate certain processes during cell aggregation and differentiation. To understand the mechanisms controlling free Ca{sup 2+} levels in this organism, the authors previously isolated and characterized an ATP/Mg{sup 2+}-dependent, high-affinity Ca{sup 2+} pump which appeared to be a component of inside-out plasma membrane vesicles. In this report, they demonstrate that a high-affinity Ca{sup 2+} pump, with properties virtually identical to the isolated pump, can be detected in filipin- or digitonin-permeabilized cells of Dictyostelium. Moreover, Ca{sup 2+}-pumping vesicles, which migrate on Percoll/KCl gradients like the vesicles identified earlier, can be isolated from the permeabilized cells. Results of additional experiments suggest that this intracellular Ca{sup 2+} transporter is associated with a high-capacity non-IP{sub 3}-releasable Ca{sup 2+} store which is generated by endocytosis. A possible role for this store in maintaining Ca{sup 2+} homeostasis in Dictyostelium is discussed.

  8. The actinome of Dictyostelium discoideum in comparison to actins and actin-related proteins from other organisms.

    Directory of Open Access Journals (Sweden)

    Jayabalan M Joseph

    Full Text Available Actin belongs to the most abundant proteins in eukaryotic cells which harbor usually many conventional actin isoforms as well as actin-related proteins (Arps. To get an overview over the sometimes confusing multitude of actins and Arps, we analyzed the Dictyostelium discoideum actinome in detail and compared it with the genomes from other model organisms. The D. discoideum actinome comprises 41 actins and actin-related proteins. The genome contains 17 actin genes which most likely arose from consecutive gene duplications, are all active, in some cases developmentally regulated and coding for identical proteins (Act8-group. According to published data, the actin fraction in a D. discoideum cell consists of more than 95% of these Act8-type proteins. The other 16 actin isoforms contain a conventional actin motif profile as well but differ in their protein sequences. Seven actin genes are potential pseudogenes. A homology search of the human genome using the most typical D. discoideum actin (Act8 as query sequence finds the major actin isoforms such as cytoplasmic beta-actin as best hit. This suggests that the Act8-group represents a nearly perfect actin throughout evolution. Interestingly, limited data from D. fasciculatum, a more ancient member among the social amoebae, show different relationships between conventional actins. The Act8-type isoform is most conserved throughout evolution. Modeling of the putative structures suggests that the majority of the actin-related proteins is functionally unrelated to canonical actin. The data suggest that the other actin variants are not necessary for the cytoskeleton itself but rather regulators of its dynamical features or subunits in larger protein complexes.

  9. Isolation of two novel ras genes in Dictyostelium discoideum; evidence for a complex, developmentally regulated ras gene subfamily.

    Science.gov (United States)

    Daniel, J; Bush, J; Cardelli, J; Spiegelman, G B; Weeks, G

    1994-02-01

    In Dictyostelium discoideum, three ras genes (rasD, rasG and rasB) and one ras-related gene (rap1) have been previously isolated and characterized, and the deduced amino acid sequence of their predicted protein products share at least 50% sequence identity with the human H-Ras protein. We have now cloned and characterized two additional members of the ras gene subfamily in Dictyostelium, rasC and rasS. These genes are developmentally regulated and unlike the previously isolated Dictyostelium ras genes, maximum levels of their transcripts were detected during aggregation, suggesting that the encoded proteins have distinct functions during aggregation. The rasC cDNA encodes a 189 amino acid protein that is 65% identical to the Dictyostelium RasD and RasG proteins and 56% identical to the human H-Ras protein. The predicted 194 amino acid gene product encoded by rasS is 60% identical to the Dictyostelium RasD and RasG proteins and 54% identical to the human H-Ras protein. Whereas RasD, RasG, RasB and Rap1 are totally conserved in their putative effector domains relative to H-Ras, RasC and RasS have single amino acid substitutions in their effector domains, consistent with the idea that they have unique functions. In RasC, aspartic acid-38 has been replaced by asparagine (D38N), and in RasS, isoleucine-36 has been replaced by leucine (I36L). In addition, both proteins have several differences in the effector-proximal domain, a domain which is believed to play a role in Ras target activation. In RasC, there is a single conservative amino acid change in the canonical sequence of the binding site for the Ras-specific monoclonal antibody Y13-259, and consequently, RasC is less immunoreactive with the antibody than either of the Dictyostelium RasD or RasG proteins. In contrast, RasS, which has three substitutions in the Y13-259 binding site, does not react with the Y13-259 antibody.

  10. NMR structural characterization of the N-terminal domain of the adenylyl cyclase-associated protein (CAP) from Dictyostelium discoideum

    Energy Technology Data Exchange (ETDEWEB)

    Mavoungou, Chrystelle [Max Planck Institute for Biochemistry (Germany); Israel, Lars [Ludwig Maximilians-University, Adolf Butenandt Institute, Cell Biology (Germany); Rehm, Till; Ksiazek, Dorota; Krajewski, Marcin; Popowicz, Grzegorz [Max Planck Institute for Biochemistry (Germany); Noegel, Angelika A. [University of Cologne, Institute for Biochemistry (Germany); Schleicher, Michael [Ludwig Maximilians-University, Adolf Butenandt Institute, Cell Biology (Germany); Holak, Tad A. [Max Planck Institute for Biochemistry (Germany)

    2004-05-15

    Cyclase-associated proteins (CAPs) are highly conserved, ubiquitous actin binding proteins that are involved in microfilament reorganization. The N-termini of CAPs play a role in Ras signaling and bind adenylyl cyclase; the C-termini bind to G-actin. We report here the NMR characterization of the amino-terminal domain of CAP from Dictyostelium discoideum (CAP(1-226)). NMR data, including the steady state {sup 1}H-{sup 15}N heteronuclear NOE experiments, indicate that the first 50 N-terminal residues are unstructured and that this highly flexible serine-rich fragment is followed by a stable, folded core starting at Ser 51. The NMR structure of the folded core is an {alpha}-helix bundle composed of six antiparallel helices, in a stark contrast to the recently determined CAP C-terminal domain structure, which is solely built by {beta}-strands.

  11. Structure of the N-terminal domain of the adenylyl cyclase-associated protein (CAP) from Dictyostelium discoideum.

    Science.gov (United States)

    Ksiazek, Dorota; Brandstetter, Hans; Israel, Lars; Bourenkov, Gleb P; Katchalova, Galina; Janssen, Klaus-Peter; Bartunik, Hans D; Noegel, Angelika A; Schleicher, Michael; Holak, Tad A

    2003-09-01

    Cyclase-associated proteins (CAPs) are widely distributed and highly conserved proteins that regulate actin remodeling in response to cellular signals. The N termini of CAPs play a role in Ras signaling and bind adenylyl cyclase; the C termini bind to G-actin and thereby alter the dynamic rearrangements of the microfilament system. We report here the X-ray structure of the core of the N-terminal domain of the CAP from Dictyostelium discoideum, which comprises residues 51-226, determined by a combination of single isomorphous replacement with anomalous scattering (SIRAS). The overall structure of this fragment is an alpha helix bundle composed of six antiparallel helices. Results from gel filtration and crosslinking experiments for CAP(1-226), CAP(255-464), and the full-length protein, together with the CAP N-terminal domain structure and the recently determined CAP C-terminal domain structure, provide evidence that the functional structure of CAP is multimeric.

  12. NMR structural characterization of the N-terminal domain of the adenylyl cyclase-associated protein (CAP) from Dictyostelium discoideum.

    Science.gov (United States)

    Mavoungou, Chrystelle; Israel, Lars; Rehm, Till; Ksiazek, Dorota; Krajewski, Marcin; Popowicz, Grzegorz; Noegel, Angelika A; Schleicher, Michael; Holak, Tad A

    2004-05-01

    Cyclase-associated proteins (CAPs) are highly conserved, ubiquitous actin binding proteins that are involved in microfilament reorganization. The N-termini of CAPs play a role in Ras signaling and bind adenylyl cyclase; the C-termini bind to G-actin. We report here the NMR characterization of the amino-terminal domain of CAP from Dictyostelium discoideum (CAP(1-226)). NMR data, including the steady state (1)H-(15)N heteronuclear NOE experiments, indicate that the first 50 N-terminal residues are unstructured and that this highly flexible serine-rich fragment is followed by a stable, folded core starting at Ser 51. The NMR structure of the folded core is an alpha-helix bundle composed of six antiparallel helices, in a stark contrast to the recently determined CAP C-terminal domain structure, which is solely built by beta-strands.

  13. Sex ratio and gamete size across eastern North America in Dictyostelium discoideum, a social amoeba with three sexes.

    Science.gov (United States)

    Douglas, T E; Strassmann, J E; Queller, D C

    2016-07-01

    Theory indicates that numbers of mating types should tend towards infinity or remain at two. The social amoeba, Dictyostelium discoideum, however, has three mating types. It is therefore a mystery how this species has broken the threshold of two mating types, but has not increased towards a much higher number. Frequency-dependent selection on rare types in combination with isogamy, a form of reproduction involving gametes similar in size, could explain the evolution of multiple mating types in this system. Other factors, such as drift, may be preventing the evolution of more than three. We first looked for evidence of isogamy by measuring gamete size associated with each type. We found no evidence of size dissimilarities between gametes. We then looked for evidence of balancing selection, by examining mating type distributions in natural populations and comparing genetic differentiation at the mating type locus to that at more neutral loci. We found that mating type frequency varied among the three populations we examined, with only one of the three showing an even sex ratio, which does not support balancing selection. However, we found more population structure at neutral loci than the mating type locus, suggesting that the three mating types are indeed maintained at intermediate frequencies by balancing selection. Overall, the data are consistent with balancing selection acting on D. discoideum mating types, but with a sufficiently weak rare sex advantage to allow for drift, a potential explanation for why these amoebae have only three mating types.

  14. Effects of an extremely low-frequency electromagnetic field on stress factors: a study in Dictyostelium discoideum cells.

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    Amaroli, Andrea; Chessa, Maria Giovanna; Bavestrello, Giorgio; Bianco, Bruno

    2013-08-01

    The development of technologies that generate environmental electromagnetic fields (EMFs) has led public opinion and the scientific community to debate upon the existence of possible effects caused by man-made EMFs on the human population and, more generally, on terrestrial ecosystems. Protozoa are known to be excellent bioassay systems in bioelectromagnetic studies because of their features that combine the reliability of in vivo results with the practicality of in vitro ones. For this reason, we examined the possible stressful effects of a 50-Hz, 300-μT extremely low-frequency electromagnetic field (ELF-EMF) on the protozoan Dictyostelium discoideum, which was used as it is included in the eight bioassay alternatives to vertebrate models for the study of human disease by the U.S. National Institutes of Health. Our results show how a 24-h exposure of D. discoideum cells to ELF-EMF can affect the net fission rate, the activity and presence of the pseudocholinesterase as well as the presence of the heat shock protein-70, while no change in the catalase and glutathione peroxidase activities was observed. However, this effect seems to be transient and all the altered parameters returned to their respective control value after a 24-h stay under dummy exposure conditions.

  15. Amoeba-resisting bacteria found in multilamellar bodies secreted by Dictyostelium discoideum: social amoebae can also package bacteria.

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    Paquet, Valérie E; Charette, Steve J

    2016-03-01

    Many bacteria can resist phagocytic digestion by various protozoa. Some of these bacteria (all human pathogens) are known to be packaged in multilamellar bodies produced in the phagocytic pathway of the protozoa and that are secreted into the extracellular milieu. Packaged bacteria are protected from harsh conditions, and the packaging process is suspected to promote bacterial persistence in the environment. To date, only a limited number of protozoa, belonging to free-living amoebae and ciliates, have been shown to perform bacteria packaging. It is still unknown if social amoebae can do bacteria packaging. The link between the capacity of 136 bacterial isolates to resist the grazing of the social amoeba Dictyostelium discoideum and to be packaged by this amoeba was investigated in the present study. The 45 bacterial isolates displaying a resisting phenotype were tested for their capacity to be packaged. A total of seven isolates from Cupriavidus, Micrococcus, Microbacterium and Rathayibacter genera seemed to be packaged and secreted by D. discoideum based on immunofluorescence results. Electron microscopy confirmed that the Cupriavidus and Rathayibacter isolates were formally packaged. These results show that social amoebae can package some bacteria from the environment revealing a new aspect of microbial ecology.

  16. The TOM Complex of Amoebozoans: the Cases of the Amoeba Acanthamoeba castellanii and the Slime Mold Dictyostelium discoideum.

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    Wojtkowska, Małgorzata; Buczek, Dorota; Stobienia, Olgierd; Karachitos, Andonis; Antoniewicz, Monika; Slocinska, Małgorzata; Makałowski, Wojciech; Kmita, Hanna

    2015-07-01

    Protein import into mitochondria requires a wide variety of proteins, forming complexes in both mitochondrial membranes. The TOM complex (translocase of the outer membrane) is responsible for decoding of targeting signals, translocation of imported proteins across or into the outer membrane, and their subsequent sorting. Thus the TOM complex is regarded as the main gate into mitochondria for imported proteins. Available data indicate that mitochondria of representative organisms from across the major phylogenetic lineages of eukaryotes differ in subunit organization of the TOM complex. The subunit organization of the TOM complex in the Amoebozoa is still elusive, so we decided to investigate its organization in the soil amoeba Acanthamoeba castellanii and the slime mold Dictyostelium discoideum. They represent two major subclades of the Amoebozoa: the Lobosa and Conosa, respectively. Our results confirm the presence of Tom70, Tom40 and Tom7 in the A. castellanii and D. discoideum TOM complex, while the presence of Tom22 and Tom20 is less supported. Interestingly, the Tom proteins display the highest similarity to Opisthokonta cognate proteins, with the exception of Tom40. Thus representatives of two major subclades of the Amoebozoa appear to be similar in organization of the TOM complex, despite differences in their lifestyle. Copyright © 2015 The Authors. Published by Elsevier GmbH.. All rights reserved.

  17. Clues to γ-secretase, huntingtin and Hirano body normal function using the model organism Dictyostelium discoideum

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    Myre Michael A

    2012-04-01

    Full Text Available Abstract Many neurodegenerative disorders, although related by their destruction of brain function, display remarkable cellular and/or regional pathogenic specificity likely due to a deregulated functionality of the mutant protein. However, neurodegenerative disease genes, for example huntingtin (HTT, the ataxins, the presenilins (PSEN1/PSEN2 are not simply localized to neurons but are ubiquitously expressed throughout peripheral tissues; it is therefore paramount to properly understand the earliest precipitating events leading to neuronal pathogenesis to develop effective long-term therapies. This means, in no unequivocal terms, it is crucial to understand the gene's normal function. Unfortunately, many genes are often essential for embryogenesis which precludes their study in whole organisms. This is true for HTT, the β-amyloid precursor protein (APP and presenilins, responsible for early onset Alzheimer's disease (AD. To better understand neurological disease in humans, many lower and higher eukaryotic models have been established. So the question arises: how reasonable is the use of organisms to study neurological disorders when the model of choice does not contain neurons? Here we will review the surprising, and novel emerging use of the model organism Dictyostelium discoideum, a species of soil-living amoeba, as a valuable biomedical tool to study the normal function of neurodegenerative genes. Historically, the evidence on the usefulness of simple organisms to understand the etiology of cellular pathology cannot be denied. But using an organism without a central nervous system to understand diseases of the brain? We will first introduce the life cycle of Dictyostelium, the presence of many disease genes in the genome and how it has provided unique opportunities to identify mechanisms of disease involving actin pathologies, mitochondrial disease, human lysosomal and trafficking disorders and host-pathogen interactions. Secondly, I will

  18. dictyExpress: a Dictyostelium discoideum gene expression database with an explorative data analysis web-based interface

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    Rot Gregor

    2009-08-01

    Full Text Available Abstract Background Bioinformatics often leverages on recent advancements in computer science to support biologists in their scientific discovery process. Such efforts include the development of easy-to-use web interfaces to biomedical databases. Recent advancements in interactive web technologies require us to rethink the standard submit-and-wait paradigm, and craft bioinformatics web applications that share analytical and interactive power with their desktop relatives, while retaining simplicity and availability. Results We have developed dictyExpress, a web application that features a graphical, highly interactive explorative interface to our database that consists of more than 1000 Dictyostelium discoideum gene expression experiments. In dictyExpress, the user can select experiments and genes, perform gene clustering, view gene expression profiles across time, view gene co-expression networks, perform analyses of Gene Ontology term enrichment, and simultaneously display expression profiles for a selected gene in various experiments. Most importantly, these tasks are achieved through web applications whose components are seamlessly interlinked and immediately respond to events triggered by the user, thus providing a powerful explorative data analysis environment. Conclusion dictyExpress is a precursor for a new generation of web-based bioinformatics applications with simple but powerful interactive interfaces that resemble that of the modern desktop. While dictyExpress serves mainly the Dictyostelium research community, it is relatively easy to adapt it to other datasets. We propose that the design ideas behind dictyExpress will influence the development of similar applications for other model organisms.

  19. The Dictyostelium discoideum acaA gene is transcribed from alternative promoters during aggregation and multicellular development.

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    Maria Galardi-Castilla

    Full Text Available BACKGROUND: Extracellular cAMP is a key extracellular signaling molecule that regulates aggregation, cell differentiation and morphogenesis during multi-cellular development of the social amoeba Dictyostelium discoideum. This molecule is produced by three different adenylyl cyclases, encoded by the genes acaA, acrA and acgA, expressed at different stages of development and in different structures. METHODOLOGY/PRINCIPAL FINDINGS: This article describes the characterization of the promoter region of the acaA gene, showing that it is transcribed from three different alternative promoters. The distal promoter, promoter 1, is active during the aggregation process while the more proximal promoters are active in tip-organiser and posterior regions of the structures. A DNA fragment containing the three promoters drove expression to these same regions and similar results were obtained by in situ hybridization. Analyses of mRNA expression by quantitative RT-PCR with specific primers for each of the three transcripts also demonstrated their different temporal patterns of expression. CONCLUSIONS/SIGNIFICANCE: The existence of an aggregation-specific promoter can be associated with the use of cAMP as chemo-attractant molecule, which is specific for some Dictyostelium species. Expression at late developmental stages indicates that adenylyl cyclase A might play a more important role in post-aggregative development than previously considered.

  20. Iron metabolism and resistance to infection by invasive bacteria in the social amoeba Dictyostelium discoideum.

    Science.gov (United States)

    Bozzaro, Salvatore; Buracco, Simona; Peracino, Barbara

    2013-01-01

    Dictyostelium cells are forest soil amoebae, which feed on bacteria and proliferate as solitary cells until bacteria are consumed. Starvation triggers a change in life style, forcing cells to gather into aggregates to form multicellular organisms capable of cell differentiation and morphogenesis. As a soil amoeba and a phagocyte that grazes on bacteria as the obligate source of food, Dictyostelium could be a natural host of pathogenic bacteria. Indeed, many pathogens that occasionally infect humans are hosted for most of their time in protozoa or free-living amoebae, where evolution of their virulence traits occurs. Due to these features and its amenability to genetic manipulation, Dictyostelium has become a valuable model organism for studying strategies of both the host to resist infection and the pathogen to escape the defense mechanisms. Similarly to higher eukaryotes, iron homeostasis is crucial for Dictyostelium resistance to invasive bacteria. Iron is essential for Dictyostelium, as both iron deficiency or overload inhibit cell growth. The Dictyostelium genome shares with mammals many genes regulating iron homeostasis. Iron transporters of the Nramp (Slc11A) family are represented with two genes, encoding Nramp1 and Nramp2. Like the mammalian ortholog, Nramp1 is recruited to phagosomes and macropinosomes, whereas Nramp2 is a membrane protein of the contractile vacuole network, which regulates osmolarity. Nramp1 and Nramp2 localization in distinct compartments suggests that both proteins synergistically regulate iron homeostasis. Rather than by absorption via membrane transporters, iron is likely gained by degradation of ingested bacteria and efflux via Nramp1 from phagosomes to the cytosol. Nramp gene disruption increases Dictyostelium sensitivity to infection, enhancing intracellular growth of Legionella or Mycobacteria. Generation of mutants in other "iron genes" will help identify genes essential for iron homeostasis and resistance to pathogens.

  1. Iron metabolism and resistance to infection by invasive bacteria in the social amoeba Dictyostelium discoideum

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    Salvatore eBozzaro

    2013-09-01

    Full Text Available Dictyostelium cells are forest soil amoebae, which feed on bacteria and proliferate as solitary cells until bacteria are consumed. Starvation triggers a change in life style, forcing cells to gather into aggregates to form multicellular organisms capable of cell differentiation and morphogenesis. As a soil amoeba and a phagocyte that grazes on bacteria as the obligate source of food, Dictyostelium could be a natural host of pathogenic bacteria. Indeed, many pathogens that occasionally infect humans are hosted for most of their time in protozoa or free-living amoebae, where evolution of their virulence traits occurs. Due to these features and its amenability to genetic manipulation, Dictyostelium has become a valuable model organism for studying strategies of both the host to resist infection and the pathogen to escape the defence mechanisms. Similarly to higher eukaryotes, iron homeostasis is crucial for Dictyostelium resistance to invasive bacteria. Iron is essential for Dictyostelium, as both iron deficiency or overload inhibit cell growth. The Dictyostelium genome shares with mammals many genes regulating iron homeostasis. Iron transporters of the Nramp (Slc11A family are represented with two genes, encoding Nramp1 and Nramp2. Like the mammalian ortholog, Nramp1 is recruited to phagosomes and macropinosomes, whereas Nramp2 is a membrane protein of the contractile vacuole network, which regulates osmolarity. Nramp1 and Nramp2 localization in distinct compartments suggests that both proteins synergistically regulate iron homeostasis. Rather than by absorption via membrane transporters, iron is likely gained by degradation of ingested bacteria and efflux via Nramp1 from phagosomes to the cytosol. Nramp gene disruption increases Dictyostelium sensitivity to infection, enhancing intracellular growth of Legionella or Mycobacteria. Generation of mutants in other "iron genes" will help identify genes essential for iron homeostasis and resistance to

  2. 1H, 15N and 13C assignments of domain 5 of Dictyostelium discoideum gelation factor (ABP-120) in its native and 8M urea-denatured states.

    Science.gov (United States)

    Hsu, Shang-Te Danny; Cabrita, Lisa D; Christodoulou, John; Dobson, Christopher M

    2009-06-01

    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.

  3. Selective down-regulation of cell surface cAMP-binding sites and cAMP-induced responses in Dictyostelium discoideum

    NARCIS (Netherlands)

    Kesbeke, Fanja; Haastert, Peter J.M. van

    1985-01-01

    Extracellular cAMP induces an intracellular accumulation of cAMP and cGMP levels in Dictyostelium discoideum, cAMP is detected by cell-surface receptors which are composed of a class of fast-dissociating sites (t1/2 = 1-2 s) and a class of slow-dissociating sites (t1/2 = 15-150 s). Exposure of D. di

  4. Two ras genes in Dictyostelium minutum show high sequence homology, but different developmental regulation from Dictyostelium discoideum rasD and rasG genes.

    Science.gov (United States)

    van Es, S; Kooistra, R A; Schaap, P

    1997-03-10

    The social amoeba Dictyostelium discoideum expresses five ras genes at different stages of development. One of them, DdrasD is expressed during postaggregative development and transcription is induced by extracellular cAMP. A homologue of DdrasD, the DdrasG gene, is expressed exclusively during vegetative growth. We cloned two ras homologues Dmras1 and Dmras2 from the primitive species D. minutum, which show high homology to DdrasD and DdrasG and less homology to the other Ddras genes. In contrast to the DdrasD and DdrasG genes, both the Dmras1 and Dmras2 genes are expressed during the entire course of development. The expression levels are low during growth, increase at the onset of starvation and do not decrease until fruiting bodies have formed. Expression of neither Dmras1 or Dmras2 is regulated by cAMP. So even though the high degree of homology between the ras genes of different species suggests conservation of function, this function is apparently not associated with a specific developmental stage.

  5. Molecular Cloning and Expression of a Phosphoinositide-specific Phospholipase C of Dictyostelium discoideum

    NARCIS (Netherlands)

    Drayer, A. Lyndsay; Haastert, Peter J.M. van

    1992-01-01

    A number of phosphoinositide-specific phospholipases C (PLC) of different species have recently been cloned. The predicted amino acid sequences of these isoforms contain two highly conserved domains. Here we report the identification of a PLC gene of Dictyostelium by using the polymerase chain

  6. Guanine Nucleotides Modulate Cell Surface cAMP-Binding Sites in Membranes from Dictyostelium discoideum

    NARCIS (Netherlands)

    Haastert, Peter J.M. van

    1984-01-01

    D. discoideum contains kinetically distinguishable cell surface cAMP binding sites. One class, S, is slowly dissociating and has high affinity for cAMP (Kd = 15 nM, t½ = 15 s). A second class is fast dissociating (t½ about 1 s) and is composed of high affinity binding sites H (Kd ≈ 60 nM), and low a

  7. Aberrant cGMP-binding activity in non-chemotactic Dictyostelium discoideum mutants

    NARCIS (Netherlands)

    Kuwayama, Hidekazu; Viel, Gerhard T.; Ishida, Shuji; Haastert, Peter J.M. van

    1995-01-01

    The kinetics of cGMP-binding to the major cGMP-binding activity in Dictyostelium, were investigated in 10 non-chemotactic mutants (KI mutants; KI-1 similar to 10). A wild-type cell contains about 3000 binding sites with a K-d of 1.5 nM. cGMP may dissociate from these binding sites with fast (F-type)

  8. Cytosolic acidification as a signal mediating hyperosmotic stress responses in Dictyostelium discoideum

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    Klein Gérard

    2001-06-01

    Full Text Available Abstract Background Dictyostelium cells exhibit an unusual response to hyperosmolarity that is distinct from the response in other organisms investigated: instead of accumulating compatible osmolytes as it has been described for a wide range of organisms, Dictyostelium cells rearrange their cytoskeleton and thereby build up a rigid network which is believed to constitute the major osmoprotective mechanism in this organism. To gain more insight into the osmoregulation of this amoeba, we investigated physiological processes affected under hyperosmotic conditions in Dictyostelium. Results We determined pH changes in response to hyperosmotic stress using FACS or 31P-NMR. Hyperosmolarity was found to acidify the cytosol from pH 7.5 to 6.8 within 5 minutes, whereas the pH of the endo-lysosomal compartment remained constant. Fluid-phase endocytosis was identified as a possible target of cytosolic acidification, as the inhibition of endocytosis observed under hypertonic conditions can be fully attributed to cytosolic acidification. In addition, a deceleration of vesicle mobility and a decrease in the NTP pool was observed. Conclusion Together, these results indicate that hyperosmotic stress triggers pleiotropic effects, which are partially mediated by a pH signal and which all contribute to the downregulation of cellular activity. The comparison of our results with the effect of hyperosmolarity and intracellular acidification on receptor-mediated endocytosis in mammalian cells reveals striking similarities, suggesting the hypothesis of the same mechanism of inhibition by low internal pH.

  9. Assessing the role of the ASP56/CAP homologue of Dictyostelium discoideum and the requirements for subcellular localization.

    Science.gov (United States)

    Noegel, A A; Rivero, F; Albrecht, R; Janssen, K P; Köhler, J; Parent, C A; Schleicher, M

    1999-10-01

    The CAP (cyclase-associated protein) homologue of Dictyostelium discoideum is a phosphatidylinositol 4,5-bisphosphate (PIP(2)) regulated G-actin sequestering protein which is present in the cytosol and shows enrichment at plasma membrane regions. It is composed of two domains separated by a proline rich stretch. The sequestering activity has been localized to the C-terminal domain of the protein, whereas the presence of the N-terminal domain seems to be required for PIP(2)-regulation of the sequestering activity. Here we have constructed GFP-fusions of N- and C-domain and found that the N-terminal domain showed CAP-specific enrichment at the anterior and posterior ends of cells like endogenous CAP irrespective of the presence of the proline rich region. Mutant cells expressing strongly reduced levels of CAP were generated by homologous recombination. They had an altered cell morphology with very heterogeneous cell sizes and exhibited a cytokinesis defect. Growth on bacteria was normal both in suspension and on agar plates as was phagocytosis of yeast and bacteria. In suspension in axenic medium mutant cells grew more slowly and did not reach saturation densities observed for wild-type cells. This was paralleled by a reduction in fluid phase endocytosis. Development was delayed by several hours under all conditions assayed, furthermore, motile behaviour was affected.

  10. Pyrimidine dimer formation and germination of UV-irradiated spores of Dictyostelium discoideum NC-4 and. gamma. s-13

    Energy Technology Data Exchange (ETDEWEB)

    Nozu, K.; Ohnishi, T.; Okaichi, K. (Nara Medical Univ., Kashihara (Japan))

    1982-04-01

    Survival, UV-photoproducts and germination of UV-irradiated spores of Dictyostelium discoideum were studied on two strains, NC-4 and ..gamma..s-13. The spores of NC-4 are about 35 times more resistant to UV than ..gamma..s-13 spores at 10% survival. Pyrimidine dimers were formed in UV-irradiated spores in both strains. No photoproducts other than pyrimidine dimers were detected. The formation of pyrimidine dimers in spores was about 2% in both strains at 800 J/m/sup 2/. In the germination of spores, the conversion of spores into swollen spores was not affected by UV in both strains, but the emergence of amoebae from the swollen spores was suppressed, which was more distinctive in ..gamma..s-13 spores than in NC-4 spores. The emerged amoebae from the UV-irradiated NC-4 spores were viable, while those from the ..gamma..s-13 spores were inviable even when they succeeded in emergence.

  11. Probabilistic transition from unstable predator-prey interaction to stable coexistence of Dictyostelium discoideum and Escherichia coli.

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    Kihara, Kumiko; Mori, Kotaro; Suzuki, Shingo; Hosoda, Kazufumi; Yamada, Akito; Matsuyama, Shin-ichi; Kashiwagi, Akiko; Yomo, Tetsuya

    2011-03-01

    Predator-prey interactions have been found at all levels within ecosystems. Despite their ecological ubiquity and importance, the process of transition to a stable coexistent state has been poorly verified experimentally. To investigate the stabilization process of predator-prey interactions, we previously constructed a reproducible experimental predator-prey system between Dictyostelium discoideum and Escherichia coli, and showed that the phenotypically changed E. coli contributed to stabilization of the system. In the present study, we focused on the transition to stable coexistence of both species after the phenotypic change in E. coli. Analysis of E. coli cells isolated from co-culture plates as single colony enabled us to readily identify the appearance of phenotypically changed E. coli that differed in colony morphology and growth rate. It was also demonstrated that two types of viscous colony, i.e., the dense-type and sparse-type, differing in spatial distribution of both species emerged probabilistically and all of the viscous colonies maintained stably were of the sparse-type. These results suggest that the phenotypically changed E. coli may produce two types of viscous colonies probabilistically. The difference in spatial distribution would affect localized interactions between both species and then cause probabilistic stabilization of predator-prey interactions.

  12. Evidence that noncoding RNA dutA is a multicopy suppressor of Dictyostelium discoideum STAT protein Dd-STATa.

    Science.gov (United States)

    Shimada, Nao; Kawata, Takefumi

    2007-06-01

    Dd-STATa, a Dictyostelium discoideum homologue of metazoan STAT transcription factors, is necessary for culmination. We created a mutant strain with partial Dd-STATa activity and used it to screen for unlinked suppressor genes. We screened approximately 450,000 clones from a slug-stage cDNA library for their ability to rescue the culmination defect when overexpressed. There were 12 multicopy suppressors of Dd-STATa, of which 4 encoded segments of a known noncoding RNA, dutA. Expression of dutA is specific to the pstA zone, the region where Dd-STATa is activated. In suppressed strains the expression patterns of several putative Dd-STATa target genes become similar to the wild-type strain. In addition, the amount of the tyrosine-phosphorylated form of Dd-STATa is significantly increased in the suppressed strain. These results indicate that partial copies of dutA may act upstream of Dd-STATa to regulate tyrosine phosphorylation by an unknown mechanism.

  13. Systematic analysis of γ-aminobutyric acid (GABA) metabolism and function in the social amoeba Dictyostelium discoideum.

    Science.gov (United States)

    Wu, Yuantai; Janetopoulos, Chris

    2013-05-24

    While GABA has been suggested to regulate spore encapsulation in the social amoeba Dictyostelium discoideum, the metabolic profile and other potential functions of GABA during development remain unclear. In this study, we investigated the homeostasis of GABA metabolism by disrupting genes related to GABA metabolism and signaling. Extracellular levels of GABA are tightly regulated during early development, and GABA is generated by the glutamate decarboxylase, GadB, during growth and in early development. However, overexpression of the prespore-specific homologue, GadA, in the presence of GadB reduces production of extracellular GABA. Perturbation of extracellular GABA levels delays the process of aggregation. Cytosolic GABA is degraded by the GABA transaminase, GabT, in the mitochondria. Disruption of a putative vesicular GABA transporter (vGAT) homologue DdvGAT reduces secreted GABA. We identified the GABAB receptor-like family member GrlB as the major GABA receptor during early development, and either disruption or overexpression of GrlB delays aggregation. This delay is likely the result of an abolished pre-starvation response and late expression of several "early" developmental genes. Distinct genes are employed for GABA generation during sporulation. During sporulation, GadA alone is required for generating GABA and DdvGAT is likely responsible for GABA secretion. GrlE but not GrlB is the GABA receptor during late development.

  14. Regulation of adenylate cyclase of Dictyostelium discoideum by divalent cations and adenosine analogs

    Energy Technology Data Exchange (ETDEWEB)

    Khachatrian, L.; Howlett, A.; Klein, C.

    1986-03-05

    Cyclic AMP is synthesized and secreted in a pulsatile fashion as a chemotactic signaling system intrinsic to the differentiation program of D. discoideum. They examined the regulation of D. dischoideum adenylate cyclase using a membrane fraction which exhibits high specific activity enzyme. When Mn-ATP was used as substrate, increasing Mn/sup 2 +/ concentrations activated the enzyme 3 to 8 fold. In contrast, Mg ion increased the adenylate cyclase activity by only 60%. These results suggested an activation of the catalytic subunit by Mn/sup 2 +/. Inhibition of activity was observed in response to adenosine and its analogs. P-site agonist, 2',5'-Dideoxy-adenosine, inhibited activity by about 25% in the presence of Mg/sup 2 +/, and about 80% in presence of Mn/sup 2 +/. This inhibition was not dependent on guanine nucleotides. The data are in agreement with characteristics of P-site regulation of the catalytic subunit of eukaryotic systems. Kinetic analysis of previously reported inhibition of D. discoideum adenylate cyclase by guanine nucleotides revealed that guanine nucleotides do not compete for the substrate binding site. Further, the enzyme activity cannot be accounted for by guanylate cyclase. Their data suggest that regulation of adenylate cyclase may exist not only at the catalytic subunit but also via inhibitory G protein, N/sub i/.

  15. Extracellular matrix family proteins that are potential targets of Dd-STATa in Dictyostelium discoideum.

    Science.gov (United States)

    Shimada, Nao; Nishio, Keiko; Maeda, Mineko; Urushihara, Hideko; Kawata, Takefumi

    2004-10-01

    Dd-STATa is a functional Dictyostelium homologue of metazoan STAT (signal transducers and activators of transcription) proteins, which is activated by cAMP and is thereby translocated into the nuclei of anterior tip cells of the prestalk region of the slug. By using in situ hybridization analyses, we found that the SLF308 cDNA clone, which contains the ecmF gene that encodes a putative extracellular matrix protein and is expressed in the anterior tip cells, was greatly down-regulated in the Dd-STATa-null mutant. Disruption of the ecmF gene, however, resulted in almost no phenotypic change. The absence of any obvious mutant phenotype in the ecmF-null mutant could be due to a redundancy of similar genes. In fact, a search of the Dictyostelium whole genome database demonstrates the existence of an additional 16 homologues, all of which contain a cellulose-binding module. Among these homologues, four genes show Dd-STATa-dependent expression, while the others are Dd-STATa-independent. We discuss the potential role of Dd-STATa in morphogenesis via its effect on the interaction between cellulose and these extracellular matrix family proteins.

  16. RNAi silenced Dd-grp94 (Dictyostelium discoideum glucose-regulated protein 94 kDa) cell lines in Dictyostelium exhibit marked reduction in growth rate and delay in development.

    Science.gov (United States)

    Baviskar, Sandhya N; Shields, Malcolm S

    2010-01-01

    Glucose-regulated 94 kDa protein (Grp94) is a resident of the endoplasmic reticulum (ER) of multicellular eukaryotes. It is a constitutively expressed protein that is overexpressed in certain abnormal conditions of the cell such as depletion of glucose and calcium, and low oxygen and pH. The protein is also implicated in diseased conditions like cancer and Alzheimer's disease. In this study, the consequences of downregulation of Grp94 were investigated at both unicellular and multicellular stages of Dictyostelium discoideum. Previous studies have shown the expression of Dd-Grp94 (Dictyostelium discoideum glucose-regulated 94 kDa protein) in wild-type cells varies during development, and overexpression of Dd-Grp94 leads to abnormal cell shape and inhibition of development (i.e., formation of fruiting bodies). Grp94 is a known calcium binding protein and an efficient calcium buffer. Therefore, in the present study we hypothesized that downregulation of Dd-Grp94 protein would affect Dictyostelium cell structure, growth, and development. We found that Dd-grp94 RNAi recombinants exhibited reduced growth rate, cell size, and a subtle change in cell motility compared to the parental cells. The recombinants also exhibited a delay in development and small fruiting bodies. These results establish that Dd-grp94 plays a crucial role in determining normal cell structure, growth and differentiation.

  17. Excision of pyrimidine dimers from nuclear deoxyribonucleic acid in ultraviolet-irradiated Dictyostelium discoideum

    Energy Technology Data Exchange (ETDEWEB)

    Clark, J.M.; Deering, R.A.

    1987-02-01

    A sensitive endonuclease assay was used to study the fate of pyrimidine dimers introduced by ultraviolet irradiation into the nuclear deoxyribonucleic acid of the cellular slime mold Dictyostellium discoideum. Analysis of the frequency of T4 endonuclease V-induced single-strand breaks by alkaline sucrose gradient sedimentation showed that strain NC4 (rad/sup +/) removed >98% of the dimers induced by irradiation at 40 J/m/sup 2/ (254 nm) within 215 min after irradiation. HPS104 (radC44), a mutant sensitive to ultraviolet irradiation, removed 91% under these conditions, although at a significantly slower rate than NC4: only 8% were removed during the 10- to 15- min period immediately after irradiation, whereas NC4 excised 64% during this interval. HPS104 thus appears to be deficient in the activity(ies) responsible for rapidly incising ultraviolet-irradiated nuclear deoxyribonucleic acid at the sites of pyrimidine dimers.

  18. Dual role of cAMP and involvement of both G-proteins and ras in regulation of ERK2 in Dictyostelium discoideum.

    Science.gov (United States)

    Knetsch, M L; Epskamp, S J; Schenk, P W; Wang, Y; Segall, J E; Snaar-Jagalska, B E

    1996-07-01

    Dictyostelium discoideum expresses two Extracellular signal Regulated Kinases, ERK1 and ERK2, which are involved in growth, multicellular development and regulation of adenylyl cyclase. Binding of extracellular cAMP to cAMP receptor 1, a G-protein coupled cell surface receptor, transiently stimulates phosphorylation, activation and nuclear translocation of ERK2. Activation of ERK2 by cAMP is dependent on heterotrimeric G-proteins, since activation of ERK2 is absent in cells lacking the Galpha4 subunit. The small G-protein rasD also activates ERK2. In cells overexpressing a mutated, constitutively active rasD, ERK2 activity is elevated prior to cAMP stimulation. Intracellular cAMP and cAMP-dependent protein kinase (PKA) are essential for adaptation of the ERK2 response. This report shows that multiple signalling pathways are involved in regulation of ERK2 activity in D.discoideum.

  19. Synthesis of ribosomal proteins in developing Dictyostelium discoideum cells is controlled by the methylation of proteins S24 and S31.

    Science.gov (United States)

    Mangiarotti, Giorgio

    2002-01-01

    Ribosomal protein mRNAs left over from growth are selectively excluded from polyribosomes in the first half of Dictyostelium discoideum development. This is due to the fact that they are sequestered by a class of free 40S ribosomal subunits, characterized by possessing a methylated S24 protein. At the time of formation of tight cell aggregates, the methylated S24 is substituted by an unmethylated S24, while protein S31 of the same or other 40S subunits becomes methylated. This leads to a rapid degradation of the ribosomal protein mRNAs.

  20. Structure, dynamics and folding of an immunoglobulin domain of the gelation factor (ABP-120) from Dictyostelium discoideum.

    Science.gov (United States)

    Hsu, Shang-Te Danny; Cabrita, Lisa D; Fucini, Paola; Dobson, Christopher M; Christodoulou, John

    2009-05-15

    We have carried out a detailed structural and dynamical characterisation of the isolated fifth repeat of the gelation factor (ABP-120) from Dictyostelium discoideum (ddFLN5) by NMR spectroscopy to provide a basis for studies of co-translational folding on the ribosome of this immunoglobulin-like domain. The isolated ddFLN5 can fold autonomously in solution into a structure that resembles very closely the crystal structure of the domain in a construct in which the adjacent sixth repeat (ddFLN6) is covalently linked to its C-terminus in tandem but deviates locally from a second crystal structure in which ddFLN5 is flanked by ddFLN4 and ddFLN6 at both N- and C-termini. Conformational fluctuations were observed via (15)N relaxation methods and are primarily localised in the interstrand loops that encompass the C-terminal hemisphere. These fluctuations are distinct in location from the region where line broadening is observed in ddFLN5 when attached to the ribosome as part of a nascent chain. This observation supports the conclusion that the broadening is associated with interactions with the ribosome surface [Hsu, S. T. D., Fucini, P., Cabrita, L. D., Launay, H., Dobson, C. M. & Christodoulou, J. (2007). Structure and dynamics of a ribosome-bound nascent chain by NMR spectroscopy. Proc. Natl. Acad. Sci. USA, 104, 16516-16521]. The unfolding of ddFLN5 induced by high concentrations of urea shows a low population of a folding intermediate, as inferred from an intensity-based analysis, a finding that differs from that of ddFLN5 as a ribosome-bound nascent chain. These results suggest that interesting differences in detail may exist between the structure of the domain in isolation and when linked to the ribosome and between protein folding in vitro and the folding of a nascent chain as it emerges from the ribosome.

  1. Toxic effects of mercury on the cell nucleus of Dictyostelium discoideum.

    Science.gov (United States)

    Boatti, Lara; Rapallo, Fabio; Viarengo, Aldo; Marsano, Francesco

    2017-02-01

    Governmental agencies (www.epa.gov/mercury) and the scientific community have reported on the high toxicity due to mercury. Indeed, exposure to mercury can cause severe injury to the central nervous system and kidney in humans. Beyond its recognized toxicity, little is known regarding the molecular mechanisms involved in the actions of this heavy metal. Mercury has been also observed to form insoluble fibrous protein aggregates in the cell nucleus. We used D. discoideum to evaluate micronuclei formation and, since mercury is able to induce oxidative stress that could bring to protein aggregation, we assessed nuclear protein carbonylation by Western Blot. We observed a significant increase in micronuclei formation and 14 carbonylated proteins were identified. Moreover, we used isotope-coded protein label (ICPL) and mass spectrometry analysis of proteins obtained by lysis of purified nuclei, before of tryptic digestion to quantify nuclear proteins affected by mercury. In particular, we examined the effects of mercury that associate a classical genotoxic assay to proteomic effects into the nucleus. The data present direct evidences for mercury genotoxicity, nuclear protein carbonylation, quantitative change in core histones, and the involvement of pseudouridine synthase in mercury toxicity. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 417-425, 2017.

  2. Seasonality can induce coexistence of multiple bet-hedging strategies in Dictyostelium discoideum via storage effect

    CERN Document Server

    Martinez-Garcia, Ricardo

    2016-01-01

    D. discoideum has been recently suggested as an example of bet-hedging. Upon starvation a population of unicellular amoebae splits between aggregators, which form a fruiting body made of a stalk and resistant spores, and non-aggregators. Spores are favored by long starvation periods, but vegetative cells can exploit resources in fast-recovering environments. This partition can be understood as a bet-hedging strategy that evolves in response to stochastic starvation times. A genotype is defined by a different balance between each type of cells. In this framework, if the ecological conditions are defined in terms of the mean starvation time (i.e. time between onset of starvation and the arrival of a new food pulse), a single genotype dominates each environment, which is inconsistent with the huge genetic diversity observed in nature. We investigate whether seasonality, represented by a periodic alternation in the mean starvation times, allows the coexistence of several strategies. We use a non-spatial (well-mix...

  3. The intracellular location of lysosomal enzymes in developing Dictyostelium discoideum cells

    Energy Technology Data Exchange (ETDEWEB)

    Lenhard, J.M.

    1989-01-01

    The author has found that developing Dictyostelium cells contain two distinct acid hydrolase-containing organelles. Vesicles from cells at different stages of development were separated using Percoll density gradients. The lower density vesicles (LDVs or lysosomes) were present in nourished and starved cells. The higher density vesicles (HDVs) arose during starvation-induced differentiation. HDVs lacked two prestalk cell-specific lysosomal enzymes which were contained in LDVs. Prespore cell-specific spore coat proteins were detected in HDVs by ELISA. ({sup 35}S)sulfate labeling revealed that HDVs contained newly made glycoproteins as well as glycoproteins found in preexisting LDVs. Pulse-chase experiments using ({sup 35}S)methionine revealed that {alpha}-mannosidase from pre-existing LDVs an newly made {alpha}-mannosidase had entered HDVs. These data suggest that prespore LDVs mature to become HDVs. He has obtained evidence that HDVs are identical to prespore vesicles. Prespore vesicles are specialized secretory organelles which arise during prespore cell differentiation and which secrete their contents during terminal differentiation. As prespore vesicles secreted their contents, there was a co-incidental increase in extracellular acid hydrolase activity and a decrease in HDV-associated enzyme activity. Electron micrographs revealed that prespore cells contained two acid phosphatase-staining organelles, one of which appeared to be identical to lysosomes from nourished cells and a second which had features similar to prespore vesicles. Ricin-gold affinity electron microscopy was used to label the mucopolysaccharide component of prespore vesicles and the spore coat. Immunoelectron microscopy revealed co-localization of {alpha}-mannosidase with ricin-gold in prespore vesicles and the spore coat.

  4. Virulence of the Pseudomonas fluorescens clinical strain MFN1032 towards Dictyostelium discoideum and macrophages in relation with type III secretion system

    Directory of Open Access Journals (Sweden)

    Sperandio Daniel

    2012-09-01

    Full Text Available Abstract Background Pseudomonas fluorescens biovar I MFN1032 is a clinical isolate able to grow at 37°C. This strain displays secretion-mediated hemolytic activity involving phospholipase C and cyclolipopeptides, and a cell-associated hemolytic activity distinct from the secreted hemolytic activity. Cell-associated hemolysis is independent of biosurfactant production and remains in a gacA mutant. Disruption of the hrpU-like operon (the basal part of type III secretion system from rhizospheric strains suppresses this activity. We hypothesized that this phenotype could reflect evolution of an ancestral mechanism involved in the survival of this species in its natural niche. In this study, we evaluated the hrpU-like operon’s contribution to other virulence mechanisms using a panel of Pseudomonas strains from various sources. Results We found that MFN1032 inhibited the growth of the amoebae Dictyostelium discoideum and that this inhibition involved the hrpU-like operon and was absent in a gacA mutant. MFN1032 was capable of causing macrophage lysis, if the hrpU-like operon was intact, and this cytotoxicity remained in a gacA mutant. Cell-associated hemolytic activity and macrophage necrosis were found in other P. fluorescens clinical isolates, but not in biocontrol P. fluorescens strains harbouring hrpU-like operon. The growth of Dictyostelium discoideum was inhibited to a different extent by P. fluorescens strains without correlation between this inhibition and hrpU-like operon sequences. Conclusions In P. fluorescens MFN1032, the basal part of type III secretion system plays a role in D. discoideum growth inhibition and macrophage necrosis. The inhibition of D. discoideum growth is dependent on the GacS/GacA system, while cell-associated hemolytic activity and macrophage lysis are not. Virulence against eukaryotic cells based on the hrpU-like operon may be more than just a stochastic evolution of a conserved system dedicated to survival in

  5. Characterization of lysosomal membrane proteins of Dictyostelium discoideum. A complex population of acidic integral membrane glycoproteins, Rab GTP-binding proteins and vacuolar ATPase subunits.

    Science.gov (United States)

    Temesvari, L; Rodriguez-Paris, J; Bush, J; Steck, T L; Cardelli, J

    1994-10-14

    Highly purified lysosomes, prepared by magnetic fractionation of homogenates from Dictyostelium discoideum cells fed colloidal iron, were lysed under hypoosmotic conditions, and the membrane-associated proteins were subjected to gel electrophoresis. Thirteen major membrane polypeptides, ranging in molecular weight from 25,000 to 100,000 were identified. The isoelectric points of these proteins ranged from below 3.8 to greater than 7.0. Most of these proteins were stripped from membranes exposed to a chaotropic agent, 3,5-diodo-2-hydroxybenzoic acid lithium salt, and were therefore classified as peripheral membrane proteins. Twenty five glycoprotein species were detected by lectin blot analysis; 19 were classified as integral membrane proteins, and were, in general, larger than 45 kDa and negatively charged due in part to the presence of mannose 6-sulfate. Western blot analysis also demonstrated that a Rab 4-like GTPase, a Rab 7-like GTPase, and at least three subunits of the vacuolar ATPase were associated with the lysosomal membrane; the ATPase subunits appeared to be major proteins in lysosomal membranes. Finally, based on N-terminal sequence analysis of a major 41-kDa lysosome-associated membrane protein, we cloned a cDNA that encodes a protein (DVA41) highly homologous to a yeast and a bovine vacuolar ATPase subunit of approximately 41 kDa. The D. discoideum DVA41 gene was apparently a single copy gene, expressed at constant levels during growth and development.

  6. Characterization and genetic mapping of modA. A mutation in the post-translational modification of the glycosidases of Dictyostelium discoideum.

    Science.gov (United States)

    Free, S J; Schimke, R T; Freeze, H; Loomis, W F

    1978-06-25

    We have isolated a mutant of Dictyostelium discoideum, M31, which produces a reduced number of alpha-mannosidase-1 molecules per cell during the developmental program of the organism. We find that several of the glycosidases, a group of lysosomal proteins produced by D. discoideum, are altered in strain M31 and that this strain produces a reduced level of at least three of these activities. These enzymes do not share a common protein subunit but are known to share a common antigenic determinant which is, in part, carbohydrate in nature. In the wild type parent of M31, alpha-mannosidase-1 is modified by the addition of mannose and glucosamine (probably as N-acetylglucosamine) in the molar ratio of 5:2. alpha-Mannosidase-1 was also found to contain phosphoserine/phosphothreonine residues. alpha-Mannosidase-1 and other glycosidases are electrophoretically less negative when isolated from strain M31 than when isolated from wild type cells. The mutation present in M31, modA, appears to affect posttranslational modification, modA is a recessive mutation which we map onto linkage group I.

  7. Relevance of the bioavailable fraction of DDT and its metabolites in freshwater sediment toxicity: New insight into the mode of action of these chemicals on Dictyostelium discoideum.

    Science.gov (United States)

    Sforzini, Susanna; Governa, Daniela; Boeri, Marta; Oliveri, Laura; Oldani, Alessandro; Vago, Fabio; Viarengo, Aldo; Borrelli, Raffaella

    2016-10-01

    In this work, the toxicity of lake sediments contaminated with DDT and its metabolites DDD and DDE (collectively, DDX) was evaluated with widely used toxicity tests (i.e., Vibrio fischeri, Daphnia magna, Pseudokirchneriella subcapitata, and Lumbriculus variegatus) and with the social amoeba Dictyostelium discoideum, a model organism that is also suitable for studying pollutant-induced alterations at the molecular and cellular levels. Although the DDX concentration in the sediments was high (732.5 ppb), the results suggested a minimal environmental risk; in fact, no evidence of harmful effects was found using the different bioassays or when we considered the results of more sensitive sublethal biomarkers in D. discoideum amoebae. In line with the biological results, the chemical data showed that the concentration of DDX in the pore water (in general a highly bioavailable phase) showed a minimal value (0.0071ppb). To confirm the importance of the bioavailability of the toxic chemicals in determining their biological effects and to investigate the mechanisms of DDX toxicity, we exposed D. discoideum amoebae to 732.5ppb DDX in water solution. DDX had no effect on cell viability; however, a strong reduction in amoebae replication rate was observed, which depended mainly on a reduction in endocytosis rate and on lysosomal and mitochondrial alterations. In the presence of a moderate and transient increase in reactive oxygen species, the glutathione level in DDX-exposed amoebae drastically decreased. These results highlight that studies of the bioavailability of pollutants in environmental matrices and their biological effects are essential for site-specific ecological risk assessment. Moreover, glutathione depletion in DDX-exposed organisms is a new finding that could open the possibility of developing new pesticide mixtures that are more effective against DDT-resistant malaria vectors.

  8. The cyclin-dependent kinase inhibitor roscovitine inhibits kinase activity, cell proliferation, multicellular development, and Cdk5 nuclear translocation in Dictyostelium discoideum.

    Science.gov (United States)

    Huber, Robert J; O'Day, Danton H

    2012-03-01

    Roscovitine, a cyclin-dependent kinase (Cdk) inhibitor, inhibited kinase activity and the axenic growth of Dictyostelium discoideum at micromolar concentrations. Growth was almost fully rescued in 50 µM and ≈ 50% rescued in 100 µM roscovitine-treated cultures by the over-expression of Cdk5-GFP. This supports the importance of Cdk5 function during cell proliferation in Dictyostelium and indicates that Cdk5 is a primary target of the drug. Roscovitine did not affect the expression of Cdk5 protein during axenic growth but did inhibit its nuclear translocation. This novel result suggests that the effects of roscovitine could be due in part to altering Cdk5 translocation in other systems as well. Kinase activity was inhibited by roscovitine in assays using AX3 whole cell lysates, but not in assays using lysates from Cdk5-GFP over-expressing cells. At higher concentrations, roscovitine impaired slug and fruiting body formation. Fruiting bodies that did form were small and produced relatively fewer spores many of which were round. However, roscovitine did not affect stalk cell differentiation. Together with previous findings, these data reveal that roscovitine inhibits Cdk5 during growth and as yet undefined Cdks during mid-late development. Copyright © 2011 Wiley Periodicals, Inc.

  9. Partial genetic suppression of a loss-of-function mutant of the neuronal ceroid lipofuscinosis-associated protease TPP1 in Dictyostelium discoideum

    Directory of Open Access Journals (Sweden)

    Jonathan E. Phillips

    2015-02-01

    Full Text Available Neuronal ceroid lipofuscinosis (NCL is the most common childhood-onset neurodegenerative disease. NCL is inevitably fatal, and there is currently no treatment available. Children with NCL show a progressive decline in movement, vision and mental abilities, and an accumulation of autofluorescent deposits in neurons and other cell types. Late-infantile NCL is caused by mutations in the lysosomal protease tripeptidyl peptidase 1 (TPP1. TPP1 cleaves tripeptides from the N-terminus of proteins in vitro, but little is known about the physiological function of TPP1. TPP1 shows wide conservation in vertebrates but it is not found in Drosophila, Caenorhabditis elegans or Saccharomyces cerevisiae. Here, we characterize ddTpp1, a TPP1 ortholog present in the social amoeba Dictyostelium discoideum. Lysates from cells lacking ddTpp1 show a reduced but not abolished ability to cleave a TPP1 substrate, suggesting that other Dictyostelium enzymes can perform this cleavage. ddTpp1 and human TPP1 localize to the lysosome in Dictyostelium, indicating conserved function and trafficking. Cells that lack ddTpp1 show precocious multicellular development and a reduced ability to form spores during development. When cultured in autophagy-stimulating conditions, cells lacking ddTpp1 rapidly decrease in size and are less viable than wild-type cells, suggesting that one function of ddTpp1 could be to limit autophagy. Cells that lack ddTpp1 exhibit strongly impaired development in the presence of the lysosome-perturbing drug chloroquine, and this phenotype can be suppressed through a secondary mutation in the gene that we name suppressor of tpp1− A (stpA, which encodes a protein with some similarity to mammalian oxysterol-binding proteins (OSBPs. Taken together, these results suggest that targeting specific proteins could be a viable way to suppress the effects of loss of TPP1 function.

  10. A model for cell type localization in the migrating slug of Dictyostelium discoideum based on differential chemotactic sensitivity to cAMP and differential sensitivity to suppression of chemotaxis by ammonia

    Indian Academy of Sciences (India)

    Ira N Feit; Jeffrey Pawlikowski; Caroline Zawilski

    2007-03-01

    The three basic cell types in the migrating slug of Dictyostelium discoideum show differential chemotactic response to cyclic AMP (cAMP) and differential sensitivity to suppression of the chemotaxis by ammonia. The values of these parameters indicate a progressive maturation of chemotactic properties during the transdifferentiation of slug cell types. We present a model that explains the localization of the three cell types within the slug based on these chemotactic differences and on the maturation of their chemotactic properties.

  11. Scanning the available Dictyostelium discoideum proteome for O-linked GlcNAc glycosylation sitesusing neural networks

    DEFF Research Database (Denmark)

    Gupta, Ramneek; Jung, Eva; Gooley, Andrew A

    1999-01-01

    glycosylated. The scan revealed acceptor sites in several proteins known experimentally to be O-glycosylated at unmapped sites. The available proteome was classified into functional and cellular compartments to study any preferential patterns of glycosylation. A sequence based prediction server for GlcNAc O......-glycosylations in D. discoideum proteins has been made available through the WWW at http://www.cbs.dtu.dk/services/DictyOGlyc/ and via E-mail to DictyOGlyc@cbs.dtu.dk....

  12. Glutathione upregulates cAMP signalling via G protein alpha 2 during the development of Dictyostelium discoideum.

    Science.gov (United States)

    Lee, Hyang-Mi; Kim, Ji-Sun; Kang, Sa-Ouk

    2016-12-01

    Despite the importance of glutathione in Dictyostelium, the role of glutathione synthetase (gshB/GSS) has not been clearly investigated. In this study, we observed that increasing glutathione content by constitutive expression of gshB leads to mound-arrest and defects in 3',5'-cyclic adenosine monophosphate (cAMP)-mediated aggregation and developmental gene expression. The overexpression of gpaB encoding G protein alpha 2 (Gα2), an essential component of the cAMP signalling pathway, results in a phenotype similar to that caused by gshB overexpression, whereas gpaB knockdown in gshB-overexpressing cells partially rescues the above-mentioned phenotypic defects. Furthermore, Gα2 is highly enriched at the plasma membrane of gshB-overexpressing cells compared to wild-type cells. Therefore, our findings suggest that glutathione upregulates cAMP signalling via Gα2 modulation during Dictyostelium development. © 2016 Federation of European Biochemical Societies.

  13. 盘基网柄菌(Dictyostelium discoideum)细胞的分化及其调控

    Institute of Scientific and Technical Information of China (English)

    付卓敏; 侯连生

    2002-01-01

    本文综述了盘基网柄菌(Dictyostelium dis-coideum)发育过程中细胞类型的诱导和分化,细胞外cAMP及其四种位于细胞表面的受体及PKA(蛋白激酶A)、GSK-3(糖原合成酶激酶)和STATa等在网柄菌发育过程中的作用.

  14. eIF2α kinases regulate development through the BzpR transcription factor in Dictyostelium discoideum.

    Directory of Open Access Journals (Sweden)

    Charles K Singleton

    Full Text Available BACKGROUND: A major mechanism of translational regulation in response to a variety of stresses is mediated by phosphorylation of eIF2α to reduce delivery of initiator tRNAs to scanning ribosomes. For some mRNAs, often encoding a bZIP transcription factor, eIF2α phosphorylation leads to enhanced translation due to delayed reinitiation at upstream open reading frames. Dictyostelium cells possess at least three eIF2α kinases that regulate various portions of the starvation-induced developmental program. Cells possessing an eIF2α that cannot be phosphorylated (BS167 show abnormalities in growth and development. We sought to identify a bZIP protein in Dictyostelium whose production is controlled by the eIF2α regulatory system. PRINCIPAL FINDINGS: Cells disrupted in the bzpR gene had similar developmental defects as BS167 cells, including small entities, stalk defects, and reduced spore viability. β-galactosidase production was used to examine translation from mRNA containing the bzpR 5' UTR. While protein production was readily apparent and regulated temporally and spatially in wild type cells, essentially no β-galactosidase was produced in developing BS167 cells even though the lacZ mRNA levels were the same as those in wild type cells. Also, no protein production was observed in strains lacking IfkA or IfkB eIF2α kinases. GFP fusions, with appropriate internal controls, were used to directly demonstrate that the bzpR 5' UTR, possessing 7 uORFs, suppressed translation by 12 fold. Suppression occurred even when all but one uORF was deleted, and translational suppression was removed when the ATG of the single uORF was mutated. CONCLUSIONS: The findings indicate that BzpR regulates aspects of the development program in Dictyostelium, serving as a downstream effector of eIF2α phosphorylation. Its production is temporally and spatially regulated by eIF2α phosphorylation by IfkA and IfkB and through the use of uORFs within the bzpR 5' UTR.

  15. G-protein-mediated interconversions of cell-surface cAMP receptors and their involvement in excitation and desensitization of guanylate cyclase in Dictyostelium discoideum

    Energy Technology Data Exchange (ETDEWEB)

    van Haastert, P.J.; de Wit, R.J.; Janssens, P.M.; Kesbeke, F.; DeGoede, J.

    1986-05-25

    In Dictyostelium discoideum cells, extracellular cAMP induces the rapid (within 2 s) activation of guanylate cyclase, which is followed by complete desensitization after about 10 s. cAMP binding to these cells is heterogeneous, showing a subclass of fast dissociating sites coupled to adenylate cyclase (A-sites) and a subclass of slowly dissociating sites coupled to guanylate cyclase (B-sites). The kinetics of the B-sites were further investigated on a seconds time scale. Statistical analysis of the association of (/sup 3/H)cAMP to the B-sites and dissociation of the complex revealed that the receptor can exist in three states which interconvert according to the following scheme. cAMP binds to the BF-state (off-rate 2.5 s) which rapidly (t1/2 = 3 s) converts to the BS-state (off-rate 15 s) and subsequently (without a detectable delay) into the BSS-state (off-rate 150 s). In membranes, both the BS- and BSS-states are converted to the BF-state by GTP and GDP, suggesting the involvement of a G-protein. Densensitized cells show a 80% reduction of the formation of the BSS-state, but no reduction of the BF- or BS-state. These data are combined into a model in which the transitions of the B-sites are mediated by a G-protein; activation of the G-protein and guanylate cyclase is associated with the transition of the BS- to the BSS-state of the receptor, whereas desensitization is associated with the inhibition of this transition.

  16. Cell type specificity and mechanism of control of a gene may be reverted in different strains of Dictyostelium discoideum.

    Science.gov (United States)

    Mangiarotti, G; Giorda, R

    2000-06-21

    Twelve genes which are expressed exclusively in pre-spore cells of Dictyostelium strain AX3 are expressed exclusively in pre-stalk cells of strain AX2. One gene has the opposite behavior: it is expressed in pre-stalk cells in AX3 and in pre-spore cells in AX2. The change in cell type specificity involves a change in the mechanism of control of gene expression. When they are expressed in pre-stalk cells, genes are controlled at the level of transcription, whilst in pre-spore cells, they are controlled at the level of mRNA stability. Genes expressed in pre-stalk cells in strain AX2, fused with an AX2 pre-spore specific promoter, become regulated at the level of mRNA stability. These findings indicate that at least a group of pre-stalk mRNAs possess the cis-destabilizing element typical of pre-spore mRNAs, though they are not destabilized in disaggregated cells. This is due to the fact that ribosomal protein S6, phosphorylation of which is responsible for controlling the stability of pre-spore mRNAs, is not dephosphorylated in disaggregated pre-stalk cells. These cells lack an S6 phosphatase activity which has been purified from disaggregated pre-spore cells.

  17. A Model for Direction Sensing in Dictyostelium discoideum: Ras Activity and Symmetry Breaking Driven by a Gβγ-Mediated, Gα2-Ric8 -- Dependent Signal Transduction Network

    Science.gov (United States)

    Cheng, Yougan; Othmer, Hans

    2016-01-01

    Chemotaxis is a dynamic cellular process, comprised of direction sensing, polarization and locomotion, that leads to the directed movement of eukaryotic cells along extracellular gradients. As a primary step in the response of an individual cell to a spatial stimulus, direction sensing has attracted numerous theoretical treatments aimed at explaining experimental observations in a variety of cell types. Here we propose a new model of direction sensing based on experiments using Dictyostelium discoideum (Dicty). The model is built around a reaction-diffusion-translocation system that involves three main component processes: a signal detection step based on G-protein-coupled receptors (GPCR) for cyclic AMP (cAMP), a transduction step based on a heterotrimetic G protein Gα2βγ, and an activation step of a monomeric G-protein Ras. The model can predict the experimentally-observed response of cells treated with latrunculin A, which removes feedback from downstream processes, under a variety of stimulus protocols. We show that Gα2βγ cycling modulated by Ric8, a nonreceptor guanine exchange factor for Gα2 in Dicty, drives multiple phases of Ras activation and leads to direction sensing and signal amplification in cAMP gradients. The model predicts that both Gα2 and Gβγ are essential for direction sensing, in that membrane-localized Gα2*, the activated GTP-bearing form of Gα2, leads to asymmetrical recruitment of RasGEF and Ric8, while globally-diffusing Gβγ mediates their activation. We show that the predicted response at the level of Ras activation encodes sufficient ‘memory’ to eliminate the ‘back-of-the wave’ problem, and the effects of diffusion and cell shape on direction sensing are also investigated. In contrast with existing LEGI models of chemotaxis, the results do not require a disparity between the diffusion coefficients of the Ras activator GEF and the Ras inhibitor GAP. Since the signal pathways we study are highly conserved between Dicty

  18. A Model for Direction Sensing in Dictyostelium discoideum: Ras Activity and Symmetry Breaking Driven by a Gβγ-Mediated, Gα2-Ric8 -- Dependent Signal Transduction Network.

    Science.gov (United States)

    Cheng, Yougan; Othmer, Hans

    2016-05-01

    Chemotaxis is a dynamic cellular process, comprised of direction sensing, polarization and locomotion, that leads to the directed movement of eukaryotic cells along extracellular gradients. As a primary step in the response of an individual cell to a spatial stimulus, direction sensing has attracted numerous theoretical treatments aimed at explaining experimental observations in a variety of cell types. Here we propose a new model of direction sensing based on experiments using Dictyostelium discoideum (Dicty). The model is built around a reaction-diffusion-translocation system that involves three main component processes: a signal detection step based on G-protein-coupled receptors (GPCR) for cyclic AMP (cAMP), a transduction step based on a heterotrimetic G protein Gα2βγ, and an activation step of a monomeric G-protein Ras. The model can predict the experimentally-observed response of cells treated with latrunculin A, which removes feedback from downstream processes, under a variety of stimulus protocols. We show that [Formula: see text] cycling modulated by Ric8, a nonreceptor guanine exchange factor for [Formula: see text] in Dicty, drives multiple phases of Ras activation and leads to direction sensing and signal amplification in cAMP gradients. The model predicts that both [Formula: see text] and Gβγ are essential for direction sensing, in that membrane-localized [Formula: see text], the activated GTP-bearing form of [Formula: see text], leads to asymmetrical recruitment of RasGEF and Ric8, while globally-diffusing Gβγ mediates their activation. We show that the predicted response at the level of Ras activation encodes sufficient 'memory' to eliminate the 'back-of-the wave' problem, and the effects of diffusion and cell shape on direction sensing are also investigated. In contrast with existing LEGI models of chemotaxis, the results do not require a disparity between the diffusion coefficients of the Ras activator GEF and the Ras inhibitor GAP. Since

  19. Ectopic expression of cyclase associated protein CAP restores the streaming and aggregation defects of adenylyl cyclase a deficient Dictyostelium discoideum cells

    OpenAIRE

    Sultana Hameeda; Neelakanta Girish; Rivero Francisco; Blau-Wasser Rosemarie; Schleicher Michael; Noegel Angelika A

    2012-01-01

    Abstract Background Cell adhesion, an integral part of D. discoideum development, is important for morphogenesis and regulated gene expression in the multicellular context and is required to trigger cell-differentiation. G-protein linked adenylyl cyclase pathways are crucially involved and a mutant lacking the aggregation specific adenylyl cyclase ACA does not undergo multicellular development. Results Here, we have investigated the role of cyclase-associated protein (CAP), an important regul...

  20. How social evolution theory impacts our understanding of development in the social amoeba Dictyostelium.

    Science.gov (United States)

    Strassmann, Joan E; Queller, David C

    2011-05-01

    Dictyostelium discoideum has been very useful for elucidating principles of development over the last 50 years, but a key attribute means there is a lot to be learned from a very different intellectual tradition: social evolution. Because Dictyostelium arrives at multicellularity by aggregation instead of through a single-cell bottleneck, the multicellular body could be made up of genetically distinct cells. If they are genetically distinct, natural selection will result in conflict over which cells become fertile spores and which become dead stalk cells. Evidence for this conflict includes unequal representation of two genetically different clones in spores of a chimera, the poison-like differentiation inducing factor (DIF) system that appears to involve some cells forcing others to become stalk, and reduced functionality in migrating chimeras. Understanding how selection operates on chimeras of genetically distinct clones is crucial for a comprehensive view of Dictyostelium multicellularity. In nature, Dictyostelium fruiting bodies are often clonal, or nearly so, meaning development will often be very cooperative. Relatedness levels tell us what benefits must be present for sociality to evolve. Therefore it is important to measure relatedness in nature, show that it has an impact on cooperation in the laboratory, and investigate genes that Dictyostelium uses to discriminate between relatives and non-relatives. Clearly, there is a promising future for research at the interface of development and social evolution in this fascinating group.

  1. Ectopic expression of cyclase associated protein CAP restores the streaming and aggregation defects of adenylyl cyclase a deficient Dictyostelium discoideum cells

    Directory of Open Access Journals (Sweden)

    Sultana Hameeda

    2012-01-01

    Full Text Available Abstract Background Cell adhesion, an integral part of D. discoideum development, is important for morphogenesis and regulated gene expression in the multicellular context and is required to trigger cell-differentiation. G-protein linked adenylyl cyclase pathways are crucially involved and a mutant lacking the aggregation specific adenylyl cyclase ACA does not undergo multicellular development. Results Here, we have investigated the role of cyclase-associated protein (CAP, an important regulator of cell polarity and F-actin/G-actin ratio in the aca- mutant. We show that ectopic expression of GFP-CAP improves cell polarization, streaming and aggregation in aca- cells, but it fails to completely restore development. Our studies indicate a requirement of CAP in the ACA dependent signal transduction for progression of the development of unicellular amoebae into multicellular structures. The reduced expression of the cell adhesion molecule DdCAD1 together with csA is responsible for the defects in aca- cells to initiate multicellular development. Early development was restored by the expression of GFP-CAP that enhanced the DdCAD1 transcript levels and to a lesser extent the csA mRNA levels. Conclusions Collectively, our data shows a novel role of CAP in regulating cell adhesion mechanisms during development that might be envisioned to unravel the functions of mammalian CAP during animal embryogenesis.

  2. 反相高效液相色谱法分析盘基网柄菌对氨基酸的利用%Analysis of Amino Acid Consumption During the Cultivation of Dictyostelium discoideum by Reversed-phase High Performance Liquid Chromatography

    Institute of Scientific and Technical Information of China (English)

    黄霄红; 王颖; 叶美玲; 罗臻; 宋娟; 凌雪萍

    2012-01-01

    In order to observe amino acid consumption during cultivation of Dictyoslelium discoideum on synthetic SIH medium, a method for determination of amino acids by reversed-phase high performance liquid chromatography(RP-HPLC) with 2, 4-dinitro-chlorobenzene derivatization was investigated. 16 amino acids could be well separated in 60 min,and a good linear relationship between peak area and concentration of amino acids was established with the correlation coefficients in the range of 0. 992-0. 999, Analysis results of samples of D. Discoideum on SIH medium indicated that lysine was completely consumed after 7 d of cultivation. Methionine, tryptophan.arginine and histidine were also utilized considerably while aspartic acid, glutamic acid, glycine, threonine, proline and valine did not show significant demand during the cell growth. This metabolic characteristic would supply reliable data to design a more reasonable synthetic medium for D. Discoideum.%为观察盘基网柄菌(Dictyostelium discoideum)在SIH培养基上对氧基酸的利用情况,以2.4-二硝基氯苯为衍生化试剂,研究了用反相高效液相色谱(RP-HPLC)测定氨基酸的方法.在60 min内16种氨基酸达到基线分离,峰面积与氨基酸浓度的线性相关系数为0.992~0.999.对发酵液样品的分析结果表明,盘基网柄菌对赖氨酸的利用最为彻底,发酵后期赖氨酸已被消耗完全.蛋氯酸、色氨酸,精氨酸、组氧酸也较易被盘基网柄菌利用,而对天冬氨酸、谷氨酸、甘氨酸、苏氨酸、脯氨酸、缬氨酸的需求不大.这一代谢特点为改进盘基网柄菌培养基组成提供依据.

  3. Lithium, an inhibitor of cAMP-induced inositol 1,4,5-trisphosphate accumulation in Dictyostelium discoideum, inhibits activation of guanine-nucleotide-binding regulatory proteins, reduces activation of adenylylcyclase, but potentiates activation of guanyl

    NARCIS (Netherlands)

    Peters, Dorien J.M.; Snaar-Jagalska, B. Ewa; Haastert, Peter J.M. van; Schaap, Pauline

    1992-01-01

    Li+ drastically alters pattern formation in Dictyostelium by inhibiting cAMP-induced prespore-gene expression and promoting cAMP-induced prestalk-gene expression. We reported previously that Li+ inhibits inositol monophosphatases in this organism and strongly reduces basal and cAMP-stimulated inosit

  4. A Biomechanical Model for Dictyostelium Motility

    CERN Document Server

    Buenemann, Mathias; Rappel, Wouter-Jan; Sander, Leonard M

    2009-01-01

    The crawling motion of Dictyostelium discoideum on substrata involves a number of coordinated events including cell contractions and cell protrusions. The mechanical forces exerted on the substratum during these contractions have recently been quantified using traction force experiments. Based on the results from these experiments, we present a biomechanical model of Dictyostelium discoideum motility with an emphasis on the adhesive properties of the cell-substratum contact. Our model assumes that the cell contracts at a constant rate and is bound to the substratum by adhesive bridges which are modeled as elastic springs. These bridges are established at a spatially uniform rate while detachment occurs at a spatially varying, load-dependent rate. Using Monte-Carlo simulations and assuming a rigid substratum, we find that the cell speed depends only weakly on the adhesive properties of the cell-substratum, in agreement with experimental data. Varying the parameters that control the adhesive and contractile pro...

  5. Developmental lineage priming in Dictyostelium by heterogeneous Ras activation.

    Science.gov (United States)

    Chattwood, Alex; Nagayama, Koki; Bolourani, Parvin; Harkin, Lauren; Kamjoo, Marzieh; Weeks, Gerald; Thompson, Christopher R L

    2013-11-26

    In cell culture, genetically identical cells often exhibit heterogeneous behavior, with only 'lineage primed' cells responding to differentiation inducing signals. It has recently been proposed that such heterogeneity exists during normal embryonic development to allow position independent patterning based on 'salt and pepper' differentiation and sorting out. However, the molecular basis of lineage priming and how it leads to reproducible cell type proportioning are poorly understood. To address this, we employed a novel forward genetic approach in the model organism Dictyostelium discoideum. These studies reveal that the Ras-GTPase regulator gefE is required for normal lineage priming and salt and pepper differentiation. This is because Ras-GTPase activity sets the intrinsic response threshold to lineage specific differentiation signals. Importantly, we show that although gefE expression is uniform, transcription of its target, rasD, is both heterogeneous and dynamic, thus providing a novel mechanism for heterogeneity generation and position-independent differentiation. DOI: http://dx.doi.org/10.7554/eLife.01067.001.

  6. Biogenesis of lysosomal enzymes in the alpha-glucosidase II-deficient modA mutant of Dictyostelium discoideum: retention of alpha-1,3-linked glucose on N-linked oligosaccharides delays intracellular transport but does not alter sorting of alpha-mannosidase or beta-glucosidase.

    Science.gov (United States)

    Ebert, D L; Bush, J M; Dimond, R L; Cardelli, J A

    1989-09-01

    The endoplasmic reticulum-localized enzyme alpha-glucosidase II is responsible for removing the two alpha-1,3-linked glucose residues from N-linked oligosaccharides of glycoproteins. This activity is missing in the modA mutant strain, M31, of Dictyostelium discoideum. Results from both radiolabeled pulse-chase and subcellular fractionation experiments indicate that this deficiency did not prevent intracellular transport and proteolytic processing of the lysosomal enzymes, alpha-mannosidase and beta-glucosidase. However, the rate at which the glucosylated precursors left the rough endoplasmic reticulum was several-fold slower than the rate at which the wild-type precursors left this compartment. Retention of glucose residues did not disrupt the binding of the precursor forms of the enzymes with intracellular membranes, indicating that the delay in movement of proteins from the ER did not result from lack of association with membranes. However, the mutant alpha-mannosidase precursor contained more trypsin-sensitive sites than did the wild-type precursor, suggesting that improper folding of precursor molecules might account for the slow rate of transport to the Golgi complex. Percoll density gradient fractionation of extracts prepared from M31 cells indicated that the proteolytically processed mature forms of alpha-mannosidase and beta-glucosidase were localized to lysosomes. Finally, the mutation in M31 may have other, more dramatic, effects on the lysosomal system since two enzymes, N-acetylglucosaminidase and acid phosphatase, were secreted much less efficiently from lysosomal compartments by the mutant strain.

  7. Intracellular adenosine 3',5'-phosphate formation is essential for down-regulation of surface adenosine 3',5'-phosphate receptors in Dictyostelium

    NARCIS (Netherlands)

    Haastert, Peter J.M. van

    1994-01-01

    Dictyostelium discoideum cells contain cell surface cyclic AMP (cAMP) receptors that bind cAMP as a first messenger and intracellular cAMP receptors that bind cAMP as a second messenger. Prolonged incubation of Dictyostelium cells with cAMP induces a sequential process of phosphorylation, sequestrat

  8. Role of phospholipase C in Dictyostelium : Formation of inositol 1,4,5-trisphosphate and normal development in cells lacking phospholipase C activity

    NARCIS (Netherlands)

    Drayer, A. Lyndsay; Kaay, Jeroen van der; Mayr, Georg W.; Haastert, Peter J.M. van

    1994-01-01

    The micro-organism Dictyostelium uses extracellular cAMP to induce chemotaxis and cell differentiation. Signals are transduced via surface receptors, which activate G proteins, to effector enzymes. The deduced protein sequence of Dictyostelium discoideum phosphabidylinositol-specific phospholipase C

  9. Developmental regulation and evolution of cAMP signaling in Dictyostelium

    NARCIS (Netherlands)

    Álvarez-Curto, Elisa

    2007-01-01

    Through evolution the social amoebas have developed mechanisms to adapt to environmental changes and ensure survival. This thesis explores the evolutionary origins of cAMP signalling and regulation of developmental decisions in the model organism Dictyostelium discoideum. It also shows the first mol

  10. Analogs of Cyclic AMP as Chemoattractants and Inhibitors of Dictyostelium Chemotaxis

    NARCIS (Netherlands)

    Haastert, Peter J.M. van; Jastorff, Bernd; Pinas, Johan E.; Konijn, Theo M.

    1982-01-01

    Aggregative amoebae of Dictyostelium discoideum, D. mucoroides, D. purpureum, and D. rosarium react chemotactically to cyclic AMP (cAMP). We measured the chemotactic activity of 14 cAMP analogs and found that these four species have a similar sensitivity to chemical modifications of cAMP; this sugge

  11. The modulation of cell surface cAMP receptors from Dictyostelium disscoideum by ammonium sulfate

    NARCIS (Netherlands)

    Haastert, Peter J.M. van

    1985-01-01

    Dictyostelium discoideum cells contain a heterogeneous population of cell surface cAMP receptors with components possessing different affinities (Kd between 15 and 450 nM) and different off-rates of the cAMP-receptor complex (t½ between 0.7 and 150 s). The association of cAMP to the receptor and the

  12. Determination of lnositol 1,4,5-Trisphosphate Levels in Dictyostelium by Isotope Dilution Assay

    NARCIS (Netherlands)

    Haastert, Peter J.M. van

    1989-01-01

    A commercial isotope dilution assay was used for the determination of Ins(1,4,5)P3 levels in the microorganism Dictyostelium discoideum. Cross-reactivity in the assay was detected with extracts from cells and the medium. The compound which induced this cross-reactivity was tentatively identified as

  13. Increased conversion of phosphatidylinositol to phosphatidylinositol phosphate in Dictyostelium cells expressing a mutated ras gene

    NARCIS (Netherlands)

    Kaay, Jeroen van der; Draijer, Richard; Haastert, Peter J.M. van

    1990-01-01

    Dictyostelium discoideum cells that overexpress a ras gene with a Gly12 → Thr12 mutation (Dd-ras-Thr12) have an altered phenotype. These cells were labeled with [3H]inositol and the incorporation of radioactivity into inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] was analyzed and found to be higher th

  14. The signal to move: D. discoideum go orienteering.

    Science.gov (United States)

    Kimmel, Alan R; Parent, Carole A

    2003-06-06

    Cells migrating directionally toward a chemoattractant source display a highly polarized cytoskeletal organization, with F-actin localized predominantly at the anterior and myosin II at the lateral and posterior regions. Dictyostelium discoideum has proven a useful system for elucidating signaling pathways that regulate this chemotactic response. During development, extracellular adenosine 3', 5' monophosphate (cAMP) functions as a primary signal to activate cell surface cAMP receptors (cARs). These receptors transduce different signals depending on whether or not they are coupled to heterotrimeric guanine nucleotide-binding proteins (G proteins) (see the STKE Connections Maps). Multiple G protein-stimulated pathways interact to establish polarity in chemotaxing D. discoideum cells by localizing F-actin at their leading edge and by regulating the phosphorylation state and assembly of myosin II. Many of the molecular interactions described are fundamental to the regulation of chemotaxis in other eukaryotic cells.

  15. Independent control of locomotion and orientation during Dictyostelium discoideum chemotaxis

    NARCIS (Netherlands)

    Duijn, Bert van; Haastert, Peter J.M. van

    1992-01-01

    Chemotaxis is cell movement in the direction of a chemical and is composed of two components: movement and directionality. The directionality of eukaryotic chemotaxis is probably derived from orientation: the detection of the spacial gradient of chemoattractant over the cell length. Chemotaxis was i

  16. Four key signaling pathways mediating chemotaxis in Dictyostelium discoideum

    NARCIS (Netherlands)

    Veltman, Douwe M.; Keizer-Gunnink, Ineke; Van Haastert, Peter J. M.

    2008-01-01

    Chemotaxis is the ability of cells to move in the direction of an external gradient of signaling molecules. Cells are guided by actin-filled protrusions in the front, whereas myosin filaments retract the rear of the cell. Previous work demonstrated that chernotaxis of unpolarized amoeboid

  17. Xpf suppresses the mutagenic consequences of phagocytosis in Dictyostelium

    Science.gov (United States)

    Langenick, Judith; Zhang, Xiao-Yin; Traynor, David; Kay, Robert R.

    2016-01-01

    ABSTRACT As time passes, mutations accumulate in the genomes of all living organisms. These changes promote genetic diversity, but also precipitate ageing and the initiation of cancer. Food is a common source of mutagens, but little is known about how nutritional factors cause lasting genetic changes in the consuming organism. Here, we describe an unusual genetic interaction between DNA repair in the unicellular amoeba Dictyostelium discoideum and its natural bacterial food source. We found that Dictyostelium deficient in the DNA repair nuclease Xpf (xpf−) display a severe and specific growth defect when feeding on bacteria. Despite being proficient in the phagocytosis and digestion of bacteria, over time, xpf− Dictyostelium feeding on bacteria cease to grow and in many instances die. The Xpf nuclease activity is required for sustained growth using a bacterial food source. Furthermore, the ingestion of this food source leads to a striking accumulation of mutations in the genome of xpf− Dictyostelium. This work therefore establishes Dictyostelium as a model genetic system to dissect nutritional genotoxicity, providing insight into how phagocytosis can induce mutagenesis and compromise survival fitness. PMID:27872153

  18. A cytohesin homolog in Dictyostelium amoebae.

    Directory of Open Access Journals (Sweden)

    Maria Christina Shina

    Full Text Available BACKGROUND: Dictyostelium, an amoeboid motile cell, harbors several paralogous Sec7 genes that encode members of three distinct subfamilies of the Sec7 superfamily of Guanine nucleotide exchange factors. Among them are proteins of the GBF/BIG family present in all eukaryotes. The third subfamily represented with three members in D. discoideum is the cytohesin family that has been thought to be metazoan specific. Cytohesins are characterized by a Sec7 PH tandem domain and have roles in cell adhesion and migration. PRINCIPAL FINDINGS: Dictyostelium SecG exhibits highest homologies to the cytohesins. It harbors at its amino terminus several ankyrin repeats that are followed by the Sec7 PH tandem domain. Mutants lacking SecG show reduced cell-substratum adhesion whereas cell-cell adhesion that is important for development is not affected. Accordingly, multicellular development proceeds normally in the mutant. During chemotaxis secG(- cells elongate and migrate in a directed fashion towards cAMP, however speed is moderately reduced. SIGNIFICANCE: The data indicate that SecG is a relevant factor for cell-substrate adhesion and reveal the basic function of a cytohesin in a lower eukaryote.

  19. Modeling oscillations and spiral waves in Dictyostelium populations

    Science.gov (United States)

    Noorbakhsh, Javad; Schwab, David J.; Sgro, Allyson E.; Gregor, Thomas; Mehta, Pankaj

    2015-06-01

    Unicellular organisms exhibit elaborate collective behaviors in response to environmental cues. These behaviors are controlled by complex biochemical networks within individual cells and coordinated through cell-to-cell communication. Describing these behaviors requires new mathematical models that can bridge scales—from biochemical networks within individual cells to spatially structured cellular populations. Here we present a family of "multiscale" models for the emergence of spiral waves in the social amoeba Dictyostelium discoideum. Our models exploit new experimental advances that allow for the direct measurement and manipulation of the small signaling molecule cyclic adenosine monophosphate (cAMP) used by Dictyostelium cells to coordinate behavior in cellular populations. Inspired by recent experiments, we model the Dictyostelium signaling network as an excitable system coupled to various preprocessing modules. We use this family of models to study spatially unstructured populations of "fixed" cells by constructing phase diagrams that relate the properties of population-level oscillations to parameters in the underlying biochemical network. We then briefly discuss an extension of our model that includes spatial structure and show how this naturally gives rise to spiral waves. Our models exhibit a wide range of novel phenomena. including a density-dependent frequency change, bistability, and dynamic death due to slow cAMP dynamics. Our modeling approach provides a powerful tool for bridging scales in modeling of Dictyostelium populations.

  20. Stochastic noise and synchronisation during Dictyostelium aggregation make cAMP oscillations robust

    OpenAIRE

    Kim, J

    2007-01-01

    Author Summary The molecular network, which underlies the oscillations in the concentration of adenosine 3′, 5′-cyclic monophosphate (cAMP) during the aggregation phase of starvation-induced development in Dictyostelium discoideum, achieves remarkable levels of robust performance in the face of environmental variations and cellular heterogeneity. However, the reasons for this robustness remain poorly understood. Tools and concepts from the field of control engineering provide powerful methods...

  1. Signal Transduction in Dictyostelium fgd A Mutants with a Defective Interaction between Surface cAMP Receptors and a GTP-binding Regulatory Protein

    NARCIS (Netherlands)

    Kesbeke, Fanja; Snaar-Jagalska, B. Ewa; Haastert, Peter J.M. van

    1988-01-01

    Transmembrane signal transduction was investigated in four Dictyostelium discoideum mutants that belong to the fgd A complementation group. The results show the following. (a) Cell surface cAMP receptors are present in fgd A mutants, but cAMP does not induce any of the intracellular responses, inclu

  2. One stop shop for everything Dictyostelium: dictyBase and the Dicty Stock Center in 2012

    Science.gov (United States)

    Fey, Petra; Dodson, Robert J.; Basu, Siddhartha; Chisholm, Rex L.

    2013-01-01

    dictyBase (http:// dictybase.org), the model organism database for Dictyostelium discoideum, includes the complete genome sequence and expression data for this organism. Relevant literature is integrated into the database, and gene models and functional annotation are manually curated from experimental results and comparative multigenome analyses. dictyBase has recently expanded to include the genome sequences of three additional Dictyostelids, and has added new software tools to facilitate multigenome comparisons. The Dicty Stock Center, a strain and plasmid repository for Dictyostelium research has relocated to Northwestern University in 2009. This allowed us integrating all Dictyostelium resources to better serve the research community. In this chapter, we will describe how to navigate the website and highlight some of our newer improvements. PMID:23494302

  3. Intracellular killing of bacteria: is Dictyostelium a model macrophage or an alien?

    Science.gov (United States)

    Cosson, Pierre; Lima, Wanessa C

    2014-01-01

    Predation of bacteria by phagocytic cells was first developed during evolution by environmental amoebae. Many of the core mechanisms used by amoebae to sense, ingest and kill bacteria have also been conserved in specialized phagocytic cells in mammalian organisms. Here we focus on recent results revealing how Dictyostelium discoideum senses and kills non-pathogenic bacteria. In this model, genetic analysis of intracellular killing of bacteria has revealed a surprisingly complex array of specialized mechanisms. These results raise new questions on these processes, and challenge current models based largely on studies in mammalian phagocytes. In addition, recent studies suggest one additional level on complexity by revealing how Dictyostelium recognizes specifically various bacterial species and strains, and adapts its metabolism to process them. It remains to be seen to what extent mechanisms uncovered in Dictyostelium are also used in mammalian phagocytic cells. PMID:24628900

  4. Studying the Protein Quality Control System of D. discoideum Using Temperature-controlled Live Cell Imaging

    Science.gov (United States)

    Malinovska, Liliana; Alberti, Simon

    2016-01-01

    The complex lifestyle of the social amoebae Dictyostelium discoideum makes it a valuable model for the study of various biological processes. Recently, we showed that D. discoideum is remarkably resilient to protein aggregation and can be used to gain insights into the cellular protein quality control system. However, the use of D. discoideum as a model system poses several challenges to microscopy-based experimental approaches, such as the high motility of the cells and their susceptibility to photo-toxicity. The latter proves to be especially challenging when studying protein homeostasis, as the phototoxic effects can induce a cellular stress response and thus alter to behavior of the protein quality control system. Temperature increase is a commonly used way to induce cellular stress. Here, we describe a temperature-controllable imaging protocol, which allows observing temperature-induced perturbations in D. discoideum. Moreover, when applied at normal growth temperature, this imaging protocol can also noticeably reduce photo-toxicity, thus allowing imaging with higher intensities. This can be particularly useful when imaging proteins with very low expression levels. Moreover, the high mobility of the cells often requires the acquisition of multiple fields of view to follow individual cells, and the number of fields needs to be balanced against the desired time interval and exposure time. PMID:28060267

  5. Simple system--substantial share: the use of Dictyostelium in cell biology and molecular medicine.

    Science.gov (United States)

    Müller-Taubenberger, Annette; Kortholt, Arjan; Eichinger, Ludwig

    2013-02-01

    Dictyostelium discoideum offers unique advantages for studying fundamental cellular processes, host-pathogen interactions as well as the molecular causes of human diseases. The organism can be easily grown in large amounts and is amenable to diverse biochemical, cell biological and genetic approaches. Throughout their life cycle Dictyostelium cells are motile, and thus are perfectly suited to study random and directed cell motility with the underlying changes in signal transduction and the actin cytoskeleton. Dictyostelium is also increasingly used for the investigation of human disease genes and the crosstalk between host and pathogen. As a professional phagocyte it can be infected with several human bacterial pathogens and used to study the infection process. The availability of a large number of knock-out mutants renders Dictyostelium particularly useful for the elucidation and investigation of host cell factors. A powerful armory of molecular genetic techniques that have been continuously expanded over the years and a well curated genome sequence, which is accessible via the online database dictyBase, considerably strengthened Dictyostelium's experimental attractiveness and its value as model organism.

  6. A stochastic description of Dictyostelium chemotaxis.

    Directory of Open Access Journals (Sweden)

    Gabriel Amselem

    Full Text Available Chemotaxis, the directed motion of a cell toward a chemical source, plays a key role in many essential biological processes. Here, we derive a statistical model that quantitatively describes the chemotactic motion of eukaryotic cells in a chemical gradient. Our model is based on observations of the chemotactic motion of the social ameba Dictyostelium discoideum, a model organism for eukaryotic chemotaxis. A large number of cell trajectories in stationary, linear chemoattractant gradients is measured, using microfluidic tools in combination with automated cell tracking. We describe the directional motion as the interplay between deterministic and stochastic contributions based on a Langevin equation. The functional form of this equation is directly extracted from experimental data by angle-resolved conditional averages. It contains quadratic deterministic damping and multiplicative noise. In the presence of an external gradient, the deterministic part shows a clear angular dependence that takes the form of a force pointing in gradient direction. With increasing gradient steepness, this force passes through a maximum that coincides with maxima in both speed and directionality of the cells. The stochastic part, on the other hand, does not depend on the orientation of the directional cue and remains independent of the gradient magnitude. Numerical simulations of our probabilistic model yield quantitative agreement with the experimental distribution functions. Thus our model captures well the dynamics of chemotactic cells and can serve to quantify differences and similarities of different chemotactic eukaryotes. Finally, on the basis of our model, we can characterize the heterogeneity within a population of chemotactic cells.

  7. Chemoattractant and guanosine 5'-[γ-thio]triphosphate induce the accumulation of inositol 1,4,5-trisphosphate in Dictyostelium cells that are labelled with [3H]inositol by electroporation

    NARCIS (Netherlands)

    Haastert, Peter J.M. van; Vries, Martinus J. de; Penning, Louis C.; Roovers, Edwin; Kaay, Jeroen van der; Erneux, Christophe; Lookeren Campagne, Michiel M. van

    1989-01-01

    The analysis of the inositol cycle in Dictyostelium discoideum cells is complicated by the limited uptake of [3H]inositol (0.2% of the applied radioactivity in 6 h), and by the conversion of [3H]inositol into water-soluble inositol metabolites that are eluted near the position of inositol 1,4,5-tris

  8. Dictyostelium phenylalanine hydroxylase is activated by its substrate phenylalanine.

    Science.gov (United States)

    Kim, Hye-Lim; Park, Mi-Bee; Kim, Yumin; Yang, Yun Gyeong; Lee, Soo-Woong; Zhuang, Ningning; Lee, Kon Ho; Park, Young Shik

    2012-10-19

    We have studied the regulatory function of Dictyostelium discoideum Ax2 phenylalanine hydroxylase (dicPAH) via characterization of domain structures. Including the full-length protein, partial proteins truncated in regulatory, tetramerization, or both, were prepared from Escherichia coli as his-tag proteins and examined for oligomeric status and catalytic parameters for phenylalanine. The proteins were also expressed extrachromosomally in the dicPAH knockout strain to examine their in vivo compatibility. The results suggest that phenylalanine activates dicPAH, which is functional in vivo as a tetramer, although cooperativity was not observed. In addition, the results of kinetic study suggest that the regulatory domain of dicPAH may play a role different from that of the domain in mammalian PAH.

  9. Burkholderia bacteria infectiously induce the proto-farming symbiosis of Dictyostelium amoebae and food bacteria.

    Science.gov (United States)

    DiSalvo, Susanne; Haselkorn, Tamara S; Bashir, Usman; Jimenez, Daniela; Brock, Debra A; Queller, David C; Strassmann, Joan E

    2015-09-01

    Symbiotic associations can allow an organism to acquire novel traits by accessing the genetic repertoire of its partner. In the Dictyostelium discoideum farming symbiosis, certain amoebas (termed "farmers") stably associate with bacterial partners. Farmers can suffer a reproductive cost but also gain beneficial capabilities, such as carriage of bacterial food (proto-farming) and defense against competitors. Farming status previously has been attributed to amoeba genotype, but the role of bacterial partners in its induction has not been examined. Here, we explore the role of bacterial associates in the initiation, maintenance, and phenotypic effects of the farming symbiosis. We demonstrate that two clades of farmer-associated Burkholderia isolates colonize D. discoideum nonfarmers and infectiously endow them with farmer-like characteristics, indicating that Burkholderia symbionts are a major driver of the farming phenomenon. Under food-rich conditions, Burkholderia-colonized amoebas produce fewer spores than uncolonized counterparts, with the severity of this reduction being dependent on the Burkholderia colonizer. However, the induction of food carriage by Burkholderia colonization may be considered a conditionally adaptive trait because it can confer an advantage to the amoeba host when grown in food-limiting conditions. We observed Burkholderia inside and outside colonized D. discoideum spores after fruiting body formation; this observation, together with the ability of Burkholderia to colonize new amoebas, suggests a mixed mode of symbiont transmission. These results change our understanding of the D. discoideum farming symbiosis by establishing that the bacterial partner, Burkholderia, is an important causative agent of the farming phenomenon.

  10. Two Dictyostelium ribosomal proteins act as RNases for specific classes of mRNAs.

    Science.gov (United States)

    Mangiarotti, Giorgio

    2003-03-01

    Phosphorylation of ribosomal protein S6 leads to the stabilization of pre-spore specific mRNAs during development of Dictyostelium discoideum. The purification of S6 kinase has allowed the identification of protein S11 as the mRNase specific for pre-spore mRNAs. Methylation of ribosomal protein S31 leads to the destabilization of ribosomal protein mRNAs. The purification of S31 methyltransferase has allowed the identification of protein S29 as the mRNAse specific for ribosomal protein mRNAs.

  11. Targets downstream of Cdk8 in Dictyostelium development

    Directory of Open Access Journals (Sweden)

    Skelton Jason

    2011-01-01

    Full Text Available Abstract Background Cdk8 is a component of the mediator complex which facilitates transcription by RNA polymerase II and has been shown to play an important role in development of Dictyostelium discoideum. This eukaryote feeds as single cells but starvation triggers the formation of a multicellular organism in response to extracellular pulses of cAMP and the eventual generation of spores. Strains in which the gene encoding Cdk8 have been disrupted fail to form multicellular aggregates unless supplied with exogenous pulses of cAMP and later in development, cdk8- cells show a defect in spore production. Results Microarray analysis revealed that the cdk8- strain previously described (cdk8-HL contained genome duplications. Regeneration of the strain in a background lacking detectable gene duplication generated strains (cdk8-2 with identical defects in growth and early development, but a milder defect in spore generation, suggesting that the severity of this defect depends on the genetic background. The failure of cdk8- cells to aggregate unless rescued by exogenous pulses of cAMP is consistent with a failure to express the catalytic subunit of protein kinase A. However, overexpression of the gene encoding this protein was not sufficient to rescue the defect, suggesting that this is not the only important target for Cdk8 at this stage of development. Proteomic analysis revealed two potential targets for Cdk8 regulation, one regulated post-transcriptionally (4-hydroxyphenylpyruvate dioxygenase (HPD and one transcriptionally (short chain dehydrogenase/reductase (SDR1. Conclusions This analysis has confirmed the importance of Cdk8 at multiple stages of Dictyostelium development, although the severity of the defect in spore production depends on the genetic background. Potential targets of Cdk8-mediated gene regulation have been identified in Dictyostelium which will allow the mechanism of Cdk8 action and its role in development to be determined.

  12. Dissecting the function of Atg1 complex in Dictyostelium autophagy reveals a connection with the pentose phosphate pathway enzyme transketolase.

    Science.gov (United States)

    Mesquita, Ana; Tábara, Luis C; Martinez-Costa, Oscar; Santos-Rodrigo, Natalia; Vincent, Olivier; Escalante, Ricardo

    2015-08-01

    The network of protein-protein interactions of the Dictyostelium discoideum autophagy pathway was investigated by yeast two-hybrid screening of the conserved autophagic proteins Atg1 and Atg8. These analyses confirmed expected interactions described in other organisms and also identified novel interactors that highlight the complexity of autophagy regulation. The Atg1 kinase complex, an essential regulator of autophagy, was investigated in detail here. The composition of the Atg1 complex in D. discoideum is more similar to mammalian cells than to Saccharomyces cerevisiae as, besides Atg13, it contains Atg101, a protein not conserved in this yeast. We found that Atg101 interacts with Atg13 and genetic disruption of these proteins in Dictyostelium leads to an early block in autophagy, although the severity of the developmental phenotype and the degree of autophagic block is higher in Atg13-deficient cells. We have also identified a protein containing zinc-finger B-box and FNIP motifs that interacts with Atg101. Disruption of this protein increases autophagic flux, suggesting that it functions as a negative regulator of Atg101. We also describe the interaction of Atg1 kinase with the pentose phosphate pathway enzyme transketolase (TKT). We found changes in the activity of endogenous TKT activity in strains lacking or overexpressing Atg1, suggesting the presence of an unsuspected regulatory pathway between autophagy and the pentose phosphate pathway in Dictyostelium that seems to be conserved in mammalian cells.

  13. Predicting the distribution of spiral waves from cell properties in a developmental-path model of Dictyostelium pattern formation.

    Directory of Open Access Journals (Sweden)

    Daniel Geberth

    2009-07-01

    Full Text Available The slime mold Dictyostelium discoideum is one of the model systems of biological pattern formation. One of the most successful answers to the challenge of establishing a spiral wave pattern in a colony of homogeneously distributed D. discoideum cells has been the suggestion of a developmental path the cells follow (Lauzeral and coworkers. This is a well-defined change in properties each cell undergoes on a longer time scale than the typical dynamics of the cell. Here we show that this concept leads to an inhomogeneous and systematic spatial distribution of spiral waves, which can be predicted from the distribution of cells on the developmental path. We propose specific experiments for checking whether such systematics are also found in data and thus, indirectly, provide evidence of a developmental path.

  14. The effects of expression of an activated rasG mutation on the differentiation of Dictyostelium.

    Science.gov (United States)

    Thiery, R; Robbins, S; Khosla, M; Spiegelman, G B; Weeks, G

    1992-01-01

    Dictyostelium discoideum contains two ras genes, rasG and rasD, that are expressed during growth and differentiation, respectively. It was shown previously that Dictyostelium transformants expressing an activated rasD gene (a mutation producing a change in amino acid 12 from glycine to threonine) developed abnormally. When developed on filters these transformants formed multitipped aggregates, which did not go on to produce final fruiting bodies, but in a submerged culture assay on a plastic surface they either formed small aggregates or did not aggregate. In this study we transformed cells with the rasG gene, mutated to change amino acid 12 from glycine to threonine. The resulting transformants developed normally on filters, but aggregation under other conditions was impaired. In particular, in submerged culture on a plastic surface they either produced very small aggregates or did not aggregate, one of the phenotypes exhibited by the activated rasD transformants. Molecular analysis of the transformants revealed the presence of high copy numbers of the mutated rasG gene, but the level of expression of the mutant gene never exceeded the level of expression of the endogenous gene. These results indicate a powerful dominant effect of a relatively small amount of the activated RasG protein in Dictyostelium.

  15. Control of cyclin C levels during development of Dictyostelium.

    Directory of Open Access Journals (Sweden)

    David M Greene

    Full Text Available BACKGROUND: Cdk8 and its partner cyclin C form part of the mediator complex which links the basal transcription machinery to regulatory proteins. The pair are required for correct regulation of a subset of genes and have been implicated in control of development in a number of organisms including the social amoeba Dictyostelium discoideum. When feeding, Dictyostelium amoebae are unicellular but upon starvation they aggregate to form a multicellular structure which develops into a fruiting body containing spores. Cells in which the gene encoding Cdk8 has been deleted fail to enter aggregates due to a failure of early gene expression. PRINCIPAL FINDINGS: We have monitored the expression levels of cyclin C protein during development and find levels decrease after the multicellular mound is formed. This decrease is triggered by extracellular cAMP that, in turn, is working in part through an increase in intracellular cAMP. The loss of cyclin C is coincident with a reduction in the association of Cdk8 with a high molecular weight complex in the nucleus. Overexpression of cyclin C and Cdk8 lead to an increased rate of early development, consistent with the levels being rate limiting. CONCLUSIONS: Overall these results show that both cyclin C and Cdk8 are regulated during development in response to extracellular signals and the levels of these proteins are important in controlling the timing of developmental processes. These findings have important implications for the role of these proteins in controlling development, suggesting that they are targets for developmental signals to regulate gene expression.

  16. Signal transduction in Dictyostelium fgd A mutants with a defective interaction between surface cAMP receptors and a GTP-binding regulatory protein [published erratum appears in J Cell Biol 1988 Dec;107(6 Pt 1):following 2463

    OpenAIRE

    1988-01-01

    Transmembrane signal transduction was investigated in four Dictyostelium discoideum mutants that belong to the fgd A complementation group. The results show the following. (a) Cell surface cAMP receptors are present in fgd A mutants, but cAMP does not induce any of the intracellular responses, including the activation of adenylate or guanylate cyclase and chemotaxis. (b) cAMP induces down- regulation and the covalent modification (presumably phosphorylation) of the cAMP receptor. (c) The inhi...

  17. Purification of the surface cAMP receptor in Dictyostelium

    Energy Technology Data Exchange (ETDEWEB)

    Klein, P.; Knox, B.; Borleis, J.; Devreotes, P.

    1987-01-05

    We have previously identified and demonstrated reversible ligand-induced modification of the major cell surface cAMP receptor in Dictyostelium discoideum. The receptor, or a subunit of it, has been purified to homogeneity by hydroxylapatite chromatography followed by two-dimensional preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purification was monitored by following /sup 32/Pi incorporated by photoaffinity labeling with 8-azido-(/sup 32/P)cAMP or by in vivo labeling with /sup 32/Pi. Two interconvertible forms of the receptor, designated R (Mr 40,000) and D (Mr 43,000), co-purified. Two-dimensional peptide maps of independently purified and /sup 125/I-iodinated R and D forms of the receptor were nearly identical but did have several distinct peptides. The estimated 6000-fold purification required is consistent with the number of cell surface binding sites assuming there are not multiple binding sites/polypeptide. In the accompanying article we report the generation of a monospecific polyclonal antiserum which has helped to further elucidate the physical properties and developmental regulation of the cAMP receptor.

  18. Analysis of specific mRNA destabilization during Dictyostelium development.

    Science.gov (United States)

    Mangiarotti, G; Bulfone, S; Giorda, R; Morandini, P; Ceccarelli, A; Hames, B D

    1989-07-01

    A number of specific mRNAs are destabilized upon disaggregation of developing Dictyostelium discoideum cells. Analysis of a family of cloned genes indicates that only prespore-enriched mRNAs are affected; constitutive mRNAs that are expressed throughout development and mRNAs that accumulate preferentially in prestalk cells are stable under these conditions. The decay of sensitive prespore mRNAs can be halted by allowing the cells to reaggregate, indicating that destabilization occurs by the progressive selection of individual molecules rather than on all members of an mRNA subpopulation at the time of disaggregation. Individual molecules of the sensitive mRNA species remain engaged in protein synthesis in the disaggregated cells until selected. Destabilization of sensitive mRNAs is induced by cell dissociation even in the presence of concentrations of nogalamycin that inhibit RNA synthesis. The reported prevention of disaggregation-induced mRNA decay by actinomycin D and daunomycin is therefore probably a secondary effect unrelated to the inhibition of transcription.

  19. Guanylate cyclase in Dictyostelium discoideum with the topology of mammalian adenylate cyclase

    NARCIS (Netherlands)

    Roelofs, J; Snippe, H; Kleineidam, RG; Van Haastert, PJM

    2001-01-01

    The core of adenylate and guanylate cyclases is formed by an intramolecular ol intermolecular dimer of two cyclase domains arranged in an antiparallel fashion. Metazoan membrane-bound adenylate cyclases are composed of 12 transmembrane spanning regions, and two cyclase domains which function as a he

  20. Ca2+ and Mg2+ binding induce conformational stability of Calfumirin-1 from Dictyostelium discoideum

    Indian Academy of Sciences (India)

    Bairagi C Mallick; Sa-Ouk Kang; Suman Jha

    2014-05-01

    The apo-Calfumirin-1 (CAF-1) binds to Ca2+ with high affinity and also to Mg2+ with high positive cooperativity. The thermal unfolding curves of wtCAF-1 monitored at neutral pH by CD spectroscopy are reversible and show different thermal stabilities in the absence or presence of Ca2+ and Mg2+ ions. Metalfree wtCAF-1 shows greater thermal stability than EF-IV mutant protein. We observed that GdnHCl-induced unfolding of apo-wtCAF-1 monitored by CD and fluorescence spectroscopies increases co-operative folding with approximately same C values. Binding of Ca2+ and Mg2+ ions to CAF-1 dramatically altered the fluorescence and CD spectra, indicating metal ion-induced conformational changes both in the wild-type and mutant proteins. The hydrophobic probe, ANS is used to observe alteration in surface hydrophobicity of the protein in different ligation states. In apo-wtCAF-1, the exposed hydrophobic surfaces are able to bind ANS which is in contrast to the unfolded or the metal ions ligated conformations. Isothermal titration calorimetry (ITC) resultsshow two possible independent binding sites of comparable affinity for the metal ions. However, their binding to the EF-IV E helix-loop-F helix mutant apo-protein happens with different affinities. The present study demonstrates that Ca2+ or Mg2+ binding plays a possible role in the conformational stability of the protein.

  1. Function of soluble guanylyl cyclase and cGMP signaling in chemotaxis of Dictyostelium discoideum

    NARCIS (Netherlands)

    Veltman, Douwe Maurits

    2007-01-01

    Losse biologische cellen kunnen gericht bewegen. De witte bloedcellen van het afweerorgaan gaan bijvoorbeeld bij een infectie actief op zoek naar bacteriën. Douwe Veltman werkte mee aan onderzoek naar het bewegingsmechanisme van het organisme Dictyostellium disoideum. Hij onderzocht de functie van

  2. EDTA treatment alters protein glycosylation in the cellular slime mold Dictyostelium discoideum

    Energy Technology Data Exchange (ETDEWEB)

    West, C.M.; Brownstein, S.A. (Univ. of Florida College of Medicine, Gainesville (USA))

    1988-03-01

    The authors have found that treatment of cells with EDTA resulted in the accumulation of lower molecular weight forms of two cell-type-specific glycoproteins. These new glycoproteins lacked a developmentally regulated glycoantigen defined by monoclonal antibody 54.2. Since EDTA dissociated the cells, the possible involvement of cell separation was tested by immobilizing cells in soft agarose. Glycoantigen expression on these proteins was found to be dependent on cAMP and high oxygen tension but not on cell contact, and was reversibly sensitive to EDTA regardless of the state of cell association. The EDTA effect was mimicked by other soluble, but not particulate, membrane impermeable chelators, could be completed by Zn{sup 2+} better than Mg{sup 2+}, and appeared to involve an intracellular mechanism. Studies with ({sup 14}C)EDTA showed that EDTA equilibrated with a cellular compartment in a temperature-dependent, Zn{sup 2+}-insensitive fashion with half-time kinetics of loading and unloading of 30-40 min. The data suggest that this step in glycosylation, which was found to be delayed 1 or more hours subsequent to protein synthesis, involves an intracellular, transition metal-ion-dependent process which can be modulated by chelators entering the cell through the endocytic pathway.

  3. Use of Nystatin-Resistant Mutations in Parasexual Genetic Analysis in DICTYOSTELIUM DISCOIDEUM

    OpenAIRE

    Kasbekar, Durgadas P.; Madigan, Sanford; Katz, Eugene R.

    1983-01-01

    Nystatin-resistant mutations exhibit extreme sensitivity to 1.3 mm coumarin. The mutations fall into three complementation groups so it is possible to select for nonallelic mutations conferring sensitivity to coumarin by selection on nystatin-containing nutrient agar plates. Complementation between such coumarin-sensitive mutations allows the selection of diploids on coumarin-containing nutrient agar. Two of the nystatin resistance genes, nysB and nysC, have been mapped tentatively to the pr...

  4. Lithium ions induce prestalk-associated gene expression and inhibit prespore gene expression in Dictyostelium discoideum

    NARCIS (Netherlands)

    Peters, Dorien J.M.; Lookeren Campagne, Michiel M. van; Haastert, Peter J.M. van; Spek, Wouter; Schaap, Pauline

    1989-01-01

    We investigated the effect of Li+ on two types of cyclic AMP-regulated gene expression and on basal and cyclic AMP-stimulated inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) levels. Li+ effectively inhibits cyclic AMP-induced prespore gene expression, half-maximal inhibition occurring at about 2mM-LiCl.

  5. Control of mRNA stability during development of Dictyostelium discoideum.

    Science.gov (United States)

    Mangiarotti, G

    1989-01-01

    A large group of mRNA species (which are mainly pre-spore specific) accumulate only after the formation of multicellular aggregates. They are transcribed at a constant rate from the beginning of development and their accumulation is controlled by a 10-20-fold increase in their stability. This mRNA stabilization is dependent upon multicellularity. When aggregates are dispersed, the mRNAs are destabilized; if cells are allowed to reaggregate, the destabilization is reversed. Destabilization is not due to a selective exclusion of mRNA from polyribosomes, but is a primary control event. It does not require synthesis of new RNA or protein, but it may require an interaction between ribosome and the 5'-end of mRNA molecules.

  6. dictyExpress: a web-based platform for sequence data management and analytics in Dictyostelium and beyond.

    Science.gov (United States)

    Stajdohar, Miha; Rosengarten, Rafael D; Kokosar, Janez; Jeran, Luka; Blenkus, Domen; Shaulsky, Gad; Zupan, Blaz

    2017-06-02

    Dictyostelium discoideum, a soil-dwelling social amoeba, is a model for the study of numerous biological processes. Research in the field has benefited mightily from the adoption of next-generation sequencing for genomics and transcriptomics. Dictyostelium biologists now face the widespread challenges of analyzing and exploring high dimensional data sets to generate hypotheses and discovering novel insights. We present dictyExpress (2.0), a web application designed for exploratory analysis of gene expression data, as well as data from related experiments such as Chromatin Immunoprecipitation sequencing (ChIP-Seq). The application features visualization modules that include time course expression profiles, clustering, gene ontology enrichment analysis, differential expression analysis and comparison of experiments. All visualizations are interactive and interconnected, such that the selection of genes in one module propagates instantly to visualizations in other modules. dictyExpress currently stores the data from over 800 Dictyostelium experiments and is embedded within a general-purpose software framework for management of next-generation sequencing data. dictyExpress allows users to explore their data in a broader context by reciprocal linking with dictyBase-a repository of Dictyostelium genomic data. In addition, we introduce a companion application called GenBoard, an intuitive graphic user interface for data management and bioinformatics analysis. dictyExpress and GenBoard enable broad adoption of next generation sequencing based inquiries by the Dictyostelium research community. Labs without the means to undertake deep sequencing projects can mine the data available to the public. The entire information flow, from raw sequence data to hypothesis testing, can be accomplished in an efficient workspace. The software framework is generalizable and represents a useful approach for any research community. To encourage more wide usage, the backend is open

  7. Dictyostelium transcriptional responses to Pseudomonas aeruginosa: common and specific effects from PAO1 and PA14 strains

    Directory of Open Access Journals (Sweden)

    Martinez José L

    2008-06-01

    Full Text Available Abstract Background Pseudomonas aeruginosa is one of the most relevant human opportunistic bacterial pathogens. Two strains (PAO1 and PA14 have been mainly used as models for studying virulence of P. aeruginosa. The strain PA14 is more virulent than PAO1 in a wide range of hosts including insects, nematodes and plants. Whereas some of the differences might be attributable to concerted action of determinants encoded in pathogenicity islands present in the genome of PA14, a global analysis of the differential host responses to these P. aeruginosa strains has not been addressed. Little is known about the host response to infection with P. aeruginosa and whether or not the global host transcription is being affected as a defense mechanism or altered in the benefit of the pathogen. Since the social amoeba Dictyostelium discoideum is a suitable host to study virulence of P. aeruginosa and other pathogens, we used available genomic tools in this model system to study the transcriptional host response to P. aeruginosa infection. Results We have compared the virulence of the P. aeruginosa PAO1 and PA14 using D. discoideum and studied the transcriptional response of the amoeba upon infection. Our results showed that PA14 is more virulent in Dictyostelium than PA01using different plating assays. For studying the differential response of the host to infection by these model strains, D. discoideum cells were exposed to either P. aeruginosa PAO1 or P. aeruginosa PA14 (mixed with an excess of the non-pathogenic bacterium Klebsiella aerogenes as food supply and after 4 hours, cellular RNA extracted. A three-way comparison was made using whole-genome D. discoideum microarrays between RNA samples from cells treated with the two different strains and control cells exposed only to K. aerogenes. The transcriptomic analyses have shown the existence of common and specific responses to infection. The expression of 364 genes changed in a similar way upon infection with

  8. Directional sensing and streaming in Dictyostelium aggregation.

    Science.gov (United States)

    Almeida, Sofia; Dilão, Rui

    2016-05-01

    We merge the Kessler-Levine simple discrete model for Dictyostelium cyclic adenosine monophosphate (cAMP) production and diffusion with the Dilão-Hauser directional sensing aggregation mechanism. The resulting compound model describes all the known transient patterns that emerge during Dictyostelium aggregation, which include the spontaneous formation of cAMP self-sustained target and spiral waves and streaming. We show that the streaming patterns depend on the speed of the amoebae, on the relaxation time for the production of cAMP, on the cAMP degradation rate, and on directional sensing. Moreover, we show that different signaling centers emerge during Dictyostelium aggregation.

  9. Comparing the Dictyostelium and Entamoeba genomes reveals an ancient split in the Conosa lineage.

    Directory of Open Access Journals (Sweden)

    Jie Song

    2005-12-01

    Full Text Available The Amoebozoa are a sister clade to the fungi and the animals, but are poorly sampled for completely sequenced genomes. The social amoeba Dictyostelium discoideum and amitochondriate pathogen Entamoeba histolytica are the first Amoebozoa with genomes completely sequenced. Both organisms are classified under the Conosa subphylum. To identify Amoebozoa-specific genomic elements, we compared these two genomes to each other and to other eukaryotic genomes. An expanded phylogenetic tree built from the complete predicted proteomes of 23 eukaryotes places the two amoebae in the same lineage, although the divergence is estimated to be greater than that between animals and fungi, and probably happened shortly after the Amoebozoa split from the opisthokont lineage. Most of the 1,500 orthologous gene families shared between the two amoebae are also shared with plant, animal, and fungal genomes. We found that only 42 gene families are distinct to the amoeba lineage; among these are a large number of proteins that contain repeats of the FNIP domain, and a putative transcription factor essential for proper cell type differentiation in D. discoideum. These Amoebozoa-specific genes may be useful in the design of novel diagnostics and therapies for amoebal pathologies.

  10. Self-organized Vortex State in Two-dimensional $Dictyostelium$ Dynamics

    CERN Document Server

    Rappel, W J; Sarkisian, A; Levine, H; Loomis, W F; Rappel, Wouter-Jan; Nicol, Alastair; Sarkissian, Armand; Levine, Herbert; Loomis, William F.

    1999-01-01

    We present results of experiments on the dynamics of {\\it Dictyostelium discoideum} in a novel set-up which constraints cell motion to a plane. After aggregation, the amoebae collect into round ''pancake" structures in which the cells rotate around the center of the pancake. This vortex state persists for many hours and we have explicitly verified that the motion is not due to rotating waves of cAMP. To provide an alternative mechanism for the self-organization of the {\\it Dictyostelium} cells, we have developed a new model of the dynamics of self-propelled deformable objects. In this model, we show that cohesive energy between the cells, together with a coupling between the self-generated propulsive force and the cell's configuration produces a self-organized vortex state. The angular velocity profiles of the experiment and of the model are qualitatively similar. The mechanism for self-organization reported here can possibly explain similar vortex states in other biological systems.

  11. Determination of inositol 1,4,5-trisphosphate levels in Dictyostelium by isotope dilution assay

    Energy Technology Data Exchange (ETDEWEB)

    Van Haastert, P.J.

    1989-02-15

    A commercial isotope dilution assay was used for the determination of Ins(1,4,5)P3 levels in the microorganism Dictyostelium discoideum. Cross-reactivity in the assay was detected with extracts from cells and the medium. The compound which induced this cross-reactivity was tentatively identified as Ins(1,4,5)P3 by (i) codegradation with authentic (/sup 32/P)Ins(1,4,5)P3 by three specific Ins(1,4,5)P3 phosphatases, and (ii) co-chromatography with authentic (/sup 32/P)Ins(1,4,5)P3 on HPLC columns. The cellular concentration was estimated as 165 +/- 42 pmol/10(8) cells, yielding a mean intracellular Ins(1,4,5)P3 concentration of 3.3 microM. Dictyostelium cells secrete large amounts of Ins(1,4,5)P3 at a rate of about 10% of the cellular content per minute, yielding about 0.13 microM extracellular Ins(1,4,5)P3 after 15 min in a suspension of 10(8) cells/ml. The chemoattractant cAMP induced a transient increase of the Ins(1,4,5)P3 concentration; the data suggest an intracacellular rise from 3.3 to 5.5 microM with a maximum at 6 s after stimulation.

  12. BTG interacts with retinoblastoma to control cell fate in Dictyostelium.

    Directory of Open Access Journals (Sweden)

    Daniele Conte

    Full Text Available BACKGROUND: In the genesis of many tissues, a phase of cell proliferation is followed by cell cycle exit and terminal differentiation. The latter two processes overlap: genes involved in the cessation of growth may also be important in triggering differentiation. Though conceptually distinct, they are often causally related and functional interactions between the cell cycle machinery and cell fate control networks are fundamental to coordinate growth and differentiation. A switch from proliferation to differentiation may also be important in the life cycle of single-celled organisms, and genes which arose as regulators of microbial differentiation may be conserved in higher organisms. Studies in microorganisms may thus contribute to understanding the molecular links between cell cycle machinery and the determination of cell fate choice networks. METHODOLOGY/PRINCIPAL FINDINGS: Here we show that in the amoebozoan D. discoideum, an ortholog of the metazoan antiproliferative gene btg controls cell fate, and that this function is dependent on the presence of a second tumor suppressor ortholog, the retinoblastoma-like gene product. Specifically, we find that btg-overexpressing cells preferentially adopt a stalk cell (and, more particularly, an Anterior-Like Cell fate. No btg-dependent preference for ALC fate is observed in cells in which the retinoblastoma-like gene has been genetically inactivated. Dictyostelium btg is the only example of non-metazoan member of the BTG family characterized so far, suggesting that a genetic interaction between btg and Rb predated the divergence between dictyostelids and metazoa. CONCLUSIONS/SIGNIFICANCE: While the requirement for retinoblastoma function for BTG antiproliferative activity in metazoans is known, an interaction of these genes in the control of cell fate has not been previously documented. Involvement of a single pathway in the control of mutually exclusive processes may have relevant implication in the

  13. Actin Foci Adhesion of D. discoideum

    Science.gov (United States)

    Flanders, Bret; Paneru, Govind

    2014-03-01

    Amoeboid migration is a fast (10 μm min-1) integrin-independent mode of migration that is important with D. discoideum, leukocytes, and breast cancer cells. It is poorly understood, but depends on the establishment of adhesive contacts to the substrate where the cell transmits traction forces. In pre-aggregative D. discoideum, a model system for learning about amoeboid migration, these adhesive contacts are discrete complexes that are known as actin-foci. They have an area of ~ 0.5 μm2 and a lifetime of ~ 20 s. This talk will present measurements of the adhesive character of actin foci that have been obtained using a submicron force transducer that was designed for this purpose. Results on the rupture stresses and lifetimes of individual acting foci under nano-newton level forces will be described in the context of a general theory for cellular adhesion. This theory depends on, essentially, three cellular properties: the membrane-medium surface tension, the number density of adhesion receptors in the membrane, and the receptor-substrate potential energy surface. Therefore, the use of the transducer to determine the surface tension will be presented, as well.

  14. An unusual protein kinase phosphorylates the chemotactic receptor of Dictystelium discoideum

    Energy Technology Data Exchange (ETDEWEB)

    Meier, K.; Klein, C. (St. Louis Univ. School of Medicine, MO (USA))

    1988-04-01

    The authors report the cAMP-dependent phosphorylation of the chemotactic receptor of Dictyostelium discoideum in partially purified plasma membranes. The protein kinase responsible for receptor phosphorylation is associated with this fraction and preferentially phosphorylates the ligand-occupied form of the receptor. 8-Azido({sup 32}P)cAMP labeling of the cell surface has shown that the cAMP receptor exists in two forms. A 45-kDa protein is predominant on unstimulated cells. cAMP stimulation results in an increased receptor phosphorylation such that the receptor migrates on NaDodSO{sub 4}/PAGE as a 47-kDa protein. Phosphorylation of the chemotactic receptor is not detected in membrane preparations unless cAMP is added to the incubation mixture. Only under those conditions is the phosphorylated 47-kDa form observed. The requirement for cAMP reflects the fact that the kinase involved preferentially uses the ligand-occupied receptor as a substrate. In vitro phosphorylation of the receptor does not involve tyrosine residues. The enzyme does not appear to be a cAMP- or cGMP-dependent protein kinase nor is it sensitive to guanine nucleotides, Ca{sup 2+}/calmodulin, Ca{sup 2+}/phospholipid, or EGTA. Similarities with the {beta}-adrenergic receptor protein kinase are discussed.

  15. Enhanced thymidine uptake causes the lowered thymidine requirement of D. discoideum auxotroph HPS 401

    Energy Technology Data Exchange (ETDEWEB)

    Hurley, D.L.; Deering, R.A. (Pennsylvania State Univ., University Park (USA))

    1988-11-01

    Dictyostelium discoideum strain HPS 401 contains a spontaneous mutation that lowers the amount of thymidine required for cell growth relative to that of the auxotrophic parental strain HPS 400. Assays for enzymes related to thymidine metabolism reveal that none of the strains tested (HPS 401, HPS 400, and prototrophic HPS 83 cells) contain detectable thymidine phosphorylase activity and that the specific activity of thymidine kinase is the same in these three strains. Thin-layer chromatography of extracts from cells grown on radiolabeled thymidine shows that there is no detectable conversion of thymidine to thymine in any of these strains. These analyses show that HPS 401 has rapid intracellular accumulation of thymidine, while only slight uptake is observed with HPS 400 or wild-type strains. HPS 401 also shows greater uptake of uridine in comparison to HPS 400 and wild-type cells. Thymidylate uptake was the same for all three strains. Thus, the mutation giving rise to the HPS 401 phenotype selectively increases the uptake of thymidine into the cell, where it can be efficiently utilized for DNA synthesis by the salvage pathways of nucleotide metabolism.

  16. Abnormalities of Endocytosis, Phagocytosis, and Development Process in Dictyostelium Cells That Over-Express Acanthamoeba castellanii Metacaspase Protein.

    Directory of Open Access Journals (Sweden)

    Entsar Saheb

    2015-06-01

    Full Text Available Acanthamoeba castellanii forms a resistant cyst that protects the parasite against the host's immune response. Acanthamoeba Type-I metacaspase (Acmcp is a caspase-like protein that has been found to be expressed during the encystations. Dictyostelium discoideum is an organism closely related to Acanthamoeba useful for studying the molecular function of this protozoan caspase-like protein.The full length of Acmcp and a mutated version of the same gene, which lacks the proline rich N-terminal region (Acmcp-dpr, were cloned into the pDneo2a-GFP vector separately. The pDneo2a-GFP-Acmcp and pDneo2a-GFPAcmcp-dpr were electro-transfected into wild type D. discoideum cells to create cell lines that over-expressed Acmcp or Acmcp-dpr.Both cell lines that over-expressed Acmcp and Acmcp-dpr showed a significant increase in the fluid phase internalization and phagocytosis rate compared to the control cells. Additionally, the cells expressing the Acmcp-dpr mutant were unable to initiate early development and failed to aggregate or form fruiting bodies under starvation conditions, whereas Acmcp over-expressing cells showed the opposite phenomena. Quantitative cell death analysis provided additional support for these findings.Acmcp is involved in the processes of endocytosis and phagocytosis. In addition, the proline rich region in Acmcp is important for cellular development in Dictyostelium. Given its important role in the development process, metacaspase protein is proposed as a candidate drug target against infections caused by A. castellanii.

  17. Phospholipase Cδ regulates germination of Dictyostelium spores

    NARCIS (Netherlands)

    Dijken, Peter van; Haastert, Peter J.M. van

    2001-01-01

    Background: Many eukaryotes, including plants and fungi make spores that resist severe environmental stress. The micro-organism Dictyostelium contains a single phospholipase C gene (PLC); deletion of the gene has no effect on growth, cell movement and differentiation. In this report we show that PLC

  18. Phospholipase Cδ regulates germination of Dictyostelium spores

    NARCIS (Netherlands)

    Dijken, Peter van; Haastert, Peter J.M. van

    2001-01-01

    Background: Many eukaryotes, including plants and fungi make spores that resist severe environmental stress. The micro-organism Dictyostelium contains a single phospholipase C gene (PLC); deletion of the gene has no effect on growth, cell movement and differentiation. In this report we show that PLC

  19. The carboxy-terminal domain of Dictyostelium C-module-binding factor is an independent gene regulatory entity.

    Directory of Open Access Journals (Sweden)

    Jörg Lucas

    Full Text Available The C-module-binding factor (CbfA is a multidomain protein that belongs to the family of jumonji-type (JmjC transcription regulators. In the social amoeba Dictyostelium discoideum, CbfA regulates gene expression during the unicellular growth phase and multicellular development. CbfA and a related D. discoideum CbfA-like protein, CbfB, share a paralogous domain arrangement that includes the JmjC domain, presumably a chromatin-remodeling activity, and two zinc finger-like (ZF motifs. On the other hand, the CbfA and CbfB proteins have completely different carboxy-terminal domains, suggesting that the plasticity of such domains may have contributed to the adaptation of the CbfA-like transcription factors to the rapid genome evolution in the dictyostelid clade. To support this hypothesis we performed DNA microarray and real-time RT-PCR measurements and found that CbfA regulates at least 160 genes during the vegetative growth of D. discoideum cells. Functional annotation of these genes revealed that CbfA predominantly controls the expression of gene products involved in housekeeping functions, such as carbohydrate, purine nucleoside/nucleotide, and amino acid metabolism. The CbfA protein displays two different mechanisms of gene regulation. The expression of one set of CbfA-dependent genes requires at least the JmjC/ZF domain of the CbfA protein and thus may depend on chromatin modulation. Regulation of the larger group of genes, however, does not depend on the entire CbfA protein and requires only the carboxy-terminal domain of CbfA (CbfA-CTD. An AT-hook motif located in CbfA-CTD, which is known to mediate DNA binding to A+T-rich sequences in vitro, contributed to CbfA-CTD-dependent gene regulatory functions in vivo.

  20. A functional connection of Dictyostelium paracaspase with the contractile vacuole and a possible partner of the vacuolar proton ATPase

    Indian Academy of Sciences (India)

    Entsar Saheb; Ithay Biton; Katherine Maringer; John Bush

    2013-09-01

    Dictyostelium discoideum possesses only one caspase family member, paracaspase (pcp). Two separate mutant cell lines were first analysed: one cell line was an over-expressed GFP-tagged Pcp (GFP-Pcp), while the other cell line was a pcp-null (pcp-). Microscopic analysis of cells expressing GFP-Pcp revealed that Pcp was associated with the contractile vacuole membrane consisting of bladder-like vacuoles. This association was disrupted when cells were exposed to osmotic stress conditions. Compared with wild-type cells, the GFP-Pcp-over-expressing cells were susceptible to osmotic stress and were seen to be very rounded in hypo-osmotic conditions and contained more abnormally swollen contractile vacuole. Cells with pcp- were also rounded but had few, if any, contractile vacuoles. These observations suggest that Pcp is essential for Dictyostelium osmotic regulation via its functioning in the contractile vacuole system. Subjecting these cells to selected contractile vacuole inhibitor provided additional support for these findings. Furthermore, yeast two-hybrid system identified vacuolar proton ATPase (VatM) as the protein interacting with Pcp. Taken together, this work gives evidence for an eukaryotic paracaspase to be associated with both localization in and regulation of the contractile vacuolar system, an organelle critical for maintaining the normal morphology of the cell.

  1. Dual chemotaxis signalling regulates Dictyostelium development: intercellular cyclic AMP pulses and intracellular F-actin disassembly waves induce each other.

    Science.gov (United States)

    Vicker, Michael G; Grutsch, James F

    2008-10-01

    Aggregating Dictyostelium discoideum amoebae periodically emit and relay cAMP, which regulates their chemotaxis and morphogenesis into a multicellular, differentiated organism. Cyclic AMP also stimulates F-actin assembly and chemotactic pseudopodium extension. We used actin-GFP expression to visualise for the first time intracellular F-actin assembly as a spatio-temporal indicator of cell reactions to cAMP, and thus the kinematics of cell communication, in aggregating streams. Every natural cAMP signal pulse induces an autowave of F-actin disassembly, which propagates from each cell's leading end to its trailing end at a linear rate, much slower than the calculated and measured velocities of cAMP diffusion in aggregating Dictyostelium. A sequence of transient reactions follows behind the wave, including anterior F-actin assembly, chemotactic pseudopodium extension and cell advance at the cell front and, at the back, F-actin assembly, extension of a small retrograde pseudopodium (forcing a brief cell retreat) and chemotactic stimulation of the following cell, yielding a 20s cAMP relay delay. These dynamics indicate that stream cell behaviour is mediated by a dual signalling system: a short-range cAMP pulse directed from one cell tail to an immediately following cell front and a slower, long-range wave of intracellular F-actin disassembly, each inducing the other.

  2. Mycobacterium marinum Degrades Both Triacylglycerols and Phospholipids from Its Dictyostelium Host to Synthesise Its Own Triacylglycerols and Generate Lipid Inclusions.

    Science.gov (United States)

    Barisch, Caroline; Soldati, Thierry

    2017-01-01

    During a tuberculosis infection and inside lipid-laden foamy macrophages, fatty acids (FAs) and sterols are the major energy and carbon source for Mycobacterium tuberculosis. Mycobacteria can be found both inside a vacuole and the cytosol, but how this impacts their access to lipids is not well appreciated. Lipid droplets (LDs) store FAs in form of triacylglycerols (TAGs) and are energy reservoirs of prokaryotes and eukaryotes. Using the Dictyostelium discoideum/Mycobacterium marinum infection model we showed that M. marinum accesses host LDs to build up its own intracytosolic lipid inclusions (ILIs). Here, we show that host LDs aggregate at regions of the bacteria that become exposed to the cytosol, and appear to coalesce on their hydrophobic surface leading to a transfer of diacylglycerol O-acyltransferase 2 (Dgat2)-GFP onto the bacteria. Dictyostelium knockout mutants for both Dgat enzymes are unable to generate LDs. Instead, the excess of exogenous FAs is esterified predominantly into phospholipids, inducing uncontrolled proliferation of the endoplasmic reticulum (ER). Strikingly, in absence of host LDs, M. marinum alternatively exploits these phospholipids, resulting in rapid reversal of ER-proliferation. In addition, the bacteria are unable to restrict their acquisition of lipids from the dgat1&2 double knockout leading to vast accumulation of ILIs. Recent data indicate that the presence of ILIs is one of the characteristics of dormant mycobacteria. During Dictyostelium infection, ILI formation in M. marinum is not accompanied by a significant change in intracellular growth and a reduction in metabolic activity, thus providing evidence that storage of neutral lipids does not necessarily induce dormancy.

  3. Disruption of Four Kinesin Genes in Dictyostelium

    Directory of Open Access Journals (Sweden)

    Soga Ikko

    2008-04-01

    Full Text Available Abstract Background Kinesin and dynein are the two families of microtubule-based motors that drive much of the intracellular movements in eukaryotic cells. Using a gene knockout strategy, we address here the individual function(s of four of the 13 kinesin proteins in Dictyostelium. The goal of our ongoing project is to establish a minimal motility proteome for this basal eukaryote, enabling us to contrast motor functions here with the often far more elaborate motor families in the metazoans. Results We performed individual disruptions of the kinesin genes, kif4, kif8, kif10, and kif11. None of the motors encoded by these genes are essential for development or viability of Dictyostelium. Removal of Kif4 (kinesin-7; CENP-E family significantly impairs the rate of cell growth and, when combined with a previously characterized dynein inhibition, results in dramatic defects in mitotic spindle assembly. Kif8 (kinesin-4; chromokinesin family and Kif10 (kinesin-8; Kip3 family appear to cooperate with dynein to organize the interphase radial microtubule array. Conclusion The results reported here extend the number of kinesin gene disruptions in Dictyostelium, to now total 10, among the 13 isoforms. None of these motors, individually, are required for short-term viability. In contrast, homologs of at least six of the 10 kinesins are considered essential in humans. Our work underscores the functional redundancy of motor isoforms in basal organisms while highlighting motor specificity in more complex metazoans. Since motor disruption in Dictyostelium can readily be combined with other motility insults and stresses, this organism offers an excellent system to investigate functional interactions among the kinesin motor family.

  4. Dicty_cDB: AFM869 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Dictyostelium discoideum slug cDNA, clone SLH341. 404 e-128 3 ( AF305060 ) Dictyostelium discoideum Wiscott-...ucing significant alignments: (bits) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott-

  5. Activation of G-proteins by receptor-stimulated nucleoside diphosphate kinase in Dictyostelium.

    Science.gov (United States)

    Bominaar, A A; Molijn, A C; Pestel, M; Veron, M; Van Haastert, P J

    1993-01-01

    Recently, interest in the enzyme nucleoside diphosphate kinase (EC2.7.4.6) has increased as a result of its possible involvement in cell proliferation and development. Since NDP kinase is one of the major sources of GTP in cells, it has been suggested that the effects of an altered NDP kinase activity on cellular processes might be the result of altered transmembrane signal transduction via guanine nucleotide-binding proteins (G-proteins). In the cellular slime mould Dictyostelium discoideum, extracellular cAMP induces an increase of phospholipase C activity via a surface cAMP receptor and G-proteins. In this paper it is demonstrated that part of the cellular NDP kinase is associated with the membrane and stimulated by cell surface cAMP receptors. The GTP produced by the action of NDP kinase is capable of activating G-proteins as monitored by altered G-protein-receptor interaction and the activation of the effector enzyme phospholipase C. Furthermore, specific monoclonal antibodies inhibit the effect of NDP kinase on G-protein activation. These results suggest that receptor-stimulated NDP kinase contributes to the mediation of hormone action by producing GTP for the activation of GTP-binding proteins. Images PMID:8389692

  6. The GATA transcription factor gene gtaG is required for terminal differentiation in Dictyostelium.

    Science.gov (United States)

    Katoh-Kurasawa, Mariko; Santhanam, Balaji; Shaulsky, Gad

    2016-03-09

    The GATA transcription factor GtaG is conserved in Dictyostelids and essential for terminal differentiation in Dictyostelium discoideum, but its function is not well understood. Here we show that gtaG is expressed in prestalk cells at the anterior region of fingers and in the extending stalk during culmination. The gtaG(-) phenotype is cell-autonomous in prestalk cells and non-cell-autonomous in prespore cells. Transcriptome analyses reveal that GtaG regulates prestalk gene expression during cell differentiation before culmination and is required for progression into culmination. GtaG-dependent genes include genetic suppressors of the Dd-STATa-defective phenotype as well as Dd-STATa target-genes, including extra cellular matrix genes. We show that GtaG may be involved in the production of two culmination-signaling molecules, cyclic di-GMP and the spore differentiation factor SDF-1 and that addition of c-di-GMP rescues the gtaG(-) culmination and spore formation deficiencies. We propose that GtaG is a regulator of terminal differentiation that functions in concert with Dd-STATa and controls culmination through regulating c-di-GMP and SDF-1 production in prestalk cells.

  7. Evidence for nucleolar subcompartments in Dictyostelium

    Energy Technology Data Exchange (ETDEWEB)

    Catalano, Andrew, E-mail: acatalano@ccny.cuny.edu [Department of Biology, University of Toronto at Mississauga, 3359 Mississauga Rd. N., Mississauga, Ontario L5L 1C6 (Canada); O’Day, Danton H., E-mail: danton.oday@utoronto.ca [Department of Biology, University of Toronto at Mississauga, 3359 Mississauga Rd. N., Mississauga, Ontario L5L 1C6 (Canada); Department of Cell and Systems Biology, University of Toronto, 25 Harbord St., Toronto, Ontario M5S 3G5 (Canada)

    2015-01-24

    Highlights: • Two nucleolar subcompartments (NoSC1, NoSC2) were found in Dictyostelium. • Specific nucleolar proteins localize to different nucleolar subcompartments. • Specific proteins exit NoSC1 and NoSC2 differently upon Actinomycin D treatment. • KRKR appears to function as an NoSC2 nucleolar subcompartment localization signal. - Abstract: The nucleolus is a multifunctional nuclear compartment usually consisting of two to three subcompartments which represent stages of ribosomal biogenesis. It is linked to several human diseases including viral infections, cancer, and neurodegeneration. Dictyostelium is a model eukaryote for the study of fundamental biological processes as well as several human diseases however comparatively little is known about its nucleolus. Unlike most nucleoli it does not possess visible subcompartments at the ultrastructural level. Several recently identified nucleolar proteins in Dictyostelium leave the nucleolus after treatment with the rDNA transcription inhibitor actinomycin-D (AM-D). Different proteins exit in different ways, suggesting that previously unidentified nucleolar subcompartments may exist. The identification of nucleolar subcompartments would help to better understand the nucleolus in this model eukaryote. Here, we show that Dictyostelium nucleolar proteins nucleomorphin isoform NumA1 and Bud31 localize throughout the entire nucleolus while calcium-binding protein 4a localizes to only a portion, representing nucleolar subcompartment 1 (NoSC1). SWI/SNF complex member Snf12 localizes to a smaller area within NoSC1 representing a second nucleolar subcompartment, NoSC2. The nuclear/nucleolar localization signal KRKR from Snf12 localized GFP to NoSC2, and thus also appears to function as a nucleolar subcompartment localization signal. FhkA localizes to the nucleolar periphery displaying a similar pattern to that of Hsp32. Similarities between the redistribution patterns of Dictyostelium nucleolar proteins during

  8. Two-dimensional electrophoretic analysis of plasma membrane protein changes associated with concanavalin A-induced capping in Dictyostelium discoideum

    Energy Technology Data Exchange (ETDEWEB)

    Patton, W.F.; Dhanak, M.R.; Savas, P.C.; Shiozawa, J.A.; Chiklis, G.R.; Jacobson, B.S.

    1986-05-01

    The colloidal silica and magnetite plasma membrane (PM) isolation techniques which are rapid, high-yielding and immobilize PM proteins, allow the study of transient cell surface changes. In addition, since the external face of the PM is shielded by the colloids, transbilayer mapping can be done by labeling the PM-proteins before and after PM isolation. PM-proteins isolated by these procedures were characterized by 2D gel analysis using microcomputer-videodensitometry. The orientation of the proteins in the bilayer was determined by LPO-catalyzed iodination. Cells were examined at four stages of concanavalin A (con A) induced capping: without ligand, after ligand binding, during receptor patching, and during receptor capping. PM-proteins were characterized with respect to their M.W., pI, Triton-insoluble cytoskeleton association, phosphorylation state, LPO iodination and con A binding. When cells were patched before Triton extraction, more PM-proteins were found associated with the cytoskeleton than without patching. Similar results were obtained with the F-actin cosedimentation assay; however, some binding occurred even in the absence of the lectin. The phosphorylation state of the PM-proteins after steady state labeling of the cells with /sup 32/PO/sub 4/ was not significantly altered by con A ligation.

  9. Ammonia differentially suppresses the cAMP chemotaxis of anterior-like cells and prestalk cells in Dictyostelium discoideum

    Indian Academy of Sciences (India)

    Ira N Feit; Erika J Medynski; Michael J Rothrock

    2001-06-01

    A drop assay for chemotaxis to cAMP confirms that both anterior-like cells (ALC) and prestalk cells (pst cells) respond to cAMP gradients. We present evidence that the chemotactic response of both ALC and pst cells is suppressed by ammonia, but a higher concentration of ammonia is required to suppress the response in pst cells. ALC show a chemotactic response to cAMP when moving on a substratum of prespore cells in isolated slug posteriors incubated under oxygen. ALC chemotaxis on a prespore cell substratum is suppressed by the same concentration of ammonia that suppresses ALC chemotaxis on the agar substratum in drop assays. Chemotaxis suppression is mediated by the unprotonated (NH3) species of ammonia. The observed suppression, by ammonia, of ALC chemotaxis to cAMP supports our earlier hypothesis that ammonia is the tip-produced suppressor of such chemotaxis. We discuss implications of ammonia sensitivity of pst cells and ALC with regard to the movement and localization of ALC and pst cells in the slug and to the roles played by ALC in fruiting body formation. In addition, we suggest that a progressive decrease in sensitivity to ammonia is an important part of the maturation of ALC into pst cells.

  10. Gene : CBRC-DDIS-02-0003 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available [Dictyostelium discoideum AX4] 0.0 100% gnl|UG|Ddi#S16822690 Dictyostelium discoideum partial dstB gene for ...NNDYNDNSSNEEENEYSIIKRKKKIKIAPTISKLLSIKKSEFNSDDNSDEESYEDDFVDYENENENENENENEYKNENENEDNKNEDNQDNDLAPSSSKLFRFLCTPKIQTNIKINNNKNKNKNKGNNDST...NNKSLISQTNNFVKSFKNENISNITFNERKNVLGMVLIKIGAGAKNNSSTRVEQKVEKEEERGEEEDFHYYLDSDGDSTISEYDIEDPFVDDSLLLIKDHAHSDSNGI

  11. Phg1/TM9 proteins control intracellular killing of bacteria by determining cellular levels of the Kil1 sulfotransferase in Dictyostelium.

    Directory of Open Access Journals (Sweden)

    Marion Le Coadic

    Full Text Available Dictyostelium discoideum has largely been used to study phagocytosis and intracellular killing of bacteria. Previous studies have shown that Phg1A, Kil1 and Kil2 proteins are necessary for efficient intracellular killing of Klebsiella bacteria. Here we show that in phg1a KO cells, cellular levels of lysosomal glycosidases and lysozyme are decreased, and lysosomal pH is increased. Surprisingly, overexpression of Kil1 restores efficient killing in phg1a KO cells without correcting these lysosomal anomalies. Conversely, kil1 KO cells are defective for killing, but their enzymatic content and lysosomal pH are indistinguishable from WT cells. The killing defect of phg1a KO cells can be accounted for by the observation that in these cells the stability and the cellular amount of Kil1 are markedly reduced. Since Kil1 is the only sulfotransferase characterized in Dictyostelium, an (unidentified sulfated factor, defective in both phg1a and kil1 KO cells, may play a key role in intracellular killing of Klebsiella bacteria. In addition, Phg1B plays a redundant role with Phg1A in controlling cellular amounts of Kil1 and intracellular killing. Finally, cellular levels of Kil1 are unaffected in kil2 KO cells, and Kil1 overexpression does not correct the killing defect of kil2 KO cells, suggesting that Kil2 plays a distinct role in intracellular killing.

  12. The protein domains of the Dictyostelium microprocessor that are required for correct subcellular localization and for microRNA maturation.

    Science.gov (United States)

    Kruse, Janis; Meier, Doreen; Zenk, Fides; Rehders, Maren; Nellen, Wolfgang; Hammann, Christian

    2016-10-02

    The maturation pathways of microRNAs (miRNAs) have been delineated for plants and several animals, belonging to the evolutionary supergroups of Archaeplastida and Opisthokonta, respectively. Recently, we reported the discovery of the microprocessor complex in Dictyostelium discoideum of the Amoebozoa supergroup. The complex is composed of the Dicer DrnB and the dsRBD (double-stranded RNA binding domain) containing protein RbdB. Both proteins localize at nucleoli, where they physically interact, and both are required for miRNA maturation. Here we show that the miRNA phenotype of a ΔdrnB gene deletion strain can be rescued by ectopic expression of a series of DrnB GFP fusion proteins, which consistently showed punctate perinucleolar localization in fluorescence microscopy. These punctate foci appear surprisingly stable, as they persist both disintegration of nucleoli and degradation of cellular nucleic acids. We observed that DrnB expression levels influence the number of microprocessor foci and alter RbdB accumulation. An investigation of DrnB variants revealed that its newly identified nuclear localization signal is necessary, but not sufficient for the perinucleolar localization. Biogenesis of miRNAs, which are RNA Pol II transcripts, is correlated with that localization. Besides its bidentate RNase III domains, DrnB contains only a dsRBD, which surprisingly is dispensable for miRNA maturation. This dsRBD can, however, functionally replace the homologous domain in RbdB. Based on the unique setup of the Dictyostelium microprocessor with a subcellular localization similar to plants, but a protein domain composition similar to animals, we propose a model for the evolutionary origin of RNase III proteins acting in miRNA maturation.

  13. Rap1 overexpression reveals that activated RasD induces separable defects during Dictyostelium development.

    Science.gov (United States)

    Louis, S A; Weeks, G; Spiegelman, G B

    1997-10-15

    One of the Dictyostelium ras genes, rasD, is expressed preferentially in prestalk cells at the slug stage of development and overexpression of this gene containing a G12T activating mutation causes the formation of aberrant multitipped aggregates that are blocked from further development (Reymond et al., 1986, Nature, 323, 340-343). The ability of the Dictyostelium rap1 gene to suppress this abnormal developmental phenotype was investigated. The rap1 gene and G12V activated and G10V negative mutant forms of the rap1 gene were independently linked to the rasD promoter and each construct used to transform M1, a Dictyostelium cell line expressing RasD[G12T]. Transformants of M1 that expressed Rap1 or Rap1[G12V] protein still formed multitipped aggregates, but most tips were able to complete development and form fruiting bodies. Cell lines showing this modified phenotype were designated ME (multitipped escape). The rap1[G10V] construct did not modify the M1 phenotype. These data suggest that overexpression of RasD[G12T] has two effects, the formation of a multitipped aggregate and a block in subsequent differentiation and that the expression of Rap1 or Rap1[G12V] reverses only the latter. Differentiation of ME cells in low density monolayers showed the identical low level of stalk and spore cell formation seen for M1 cells under the same conditions. Thus the cell autonomous defect in monolayer differentiation induced in the M1 strain was not corrected in the ME strain. Cell type-specific gene expression during the development of M1 cells is dramatically altered: prestalk cell-specific gene expression is greatly enhanced, whereas prespore-specific gene expression is almost suppressed (Louis et al., 1997, Mol. Biol. Cell, 8, 303-312). During the development of ME cells, ecmA mRNA levels were restored to those seen for Ax3, and tagB mRNA levels were also markedly reduced, although not to Ax3 levels. cotC expression in ME cells was enhanced severalfold relative to M1

  14. Dispatch. Dictyostelium chemotaxis: fascism through the back door?

    Science.gov (United States)

    Insall, Robert

    2003-04-29

    Aggregating Dictyostelium cells secrete cyclic AMP to attract their neighbours by chemotaxis. It has now been shown that adenylyl cyclase is enriched in the rear of cells, and this localisation is required for normal aggregation.

  15. Shell tension forces propel Dictyostelium slugs forward.

    Science.gov (United States)

    Rieu, Jean-Paul; Delanoë-Ayari, Hélène

    2012-12-01

    The Dictyostelium slug is an excellent model system for studying collective movements, as it is comprised of about 10(5) cells all moving together in the same direction. It still remains unclear how this movement occurs and what the physical mechanisms behind it are. By applying our recently developed 3D traction force microscopy, we propose a simple explanation for slug propulsion. Most of the forces are exerted by the sheath surrounding the slug. This secreted shell is under a rather uniform tension (around 50 mN m(-1)) and will give rise to a tissue under pressure. Finally, we propose that this pressure will naturally push the slug tip forwards if a gradient of shell mechanical properties takes place in the very anterior part of the raised tip.

  16. Shell tension forces propel Dictyostelium slugs forward

    Science.gov (United States)

    Rieu, Jean-Paul; Delanoë-Ayari, Hélène

    2012-12-01

    The Dictyostelium slug is an excellent model system for studying collective movements, as it is comprised of about 105 cells all moving together in the same direction. It still remains unclear how this movement occurs and what the physical mechanisms behind it are. By applying our recently developed 3D traction force microscopy, we propose a simple explanation for slug propulsion. Most of the forces are exerted by the sheath surrounding the slug. This secreted shell is under a rather uniform tension (around 50 mN m-1) and will give rise to a tissue under pressure. Finally, we propose that this pressure will naturally push the slug tip forwards if a gradient of shell mechanical properties takes place in the very anterior part of the raised tip.

  17. Analogs of cyclic AMP as chemoattractants and inhibitors of Dictyostelium chemotaxis.

    Science.gov (United States)

    Van Haastert, P J; Jastorff, B; Pinas, J E; Konijn, T M

    1982-01-01

    Aggregative amoebae of Dictyostelium discoideum, D. mucoroides, D. purpureum, and D. rosarium react chemotactically to cyclic AMP (cAMP). We measured the chemotactic activity of 14 cAMP analogs and found that these four species have a similar sensitivity to chemical modifications of cAMP; this suggests that the cAMP receptor is identical in all of these species. Besides the induction of a chemotactic response, cAMP analogs also may delay or prevent cell aggregation. cAMP analogs like N1-O-cAMP, 2'-H-cAMP, and 5'NH-cAMP are chemotactically nearly as active as cAMP and induced no, or only a short, delay of cell aggregation. Other cAMP derivatives, such as 6-Cl-cPMP and 8-Br-cAMP, are chemotactically active only at high concentrations and delayed cell aggregation for several hours. Still other cAMP analogs, which do not induce a chemotactic reaction in D. mucoroides, D. purpureum, and D. rosarium, either prevented cell aggregation [cAMPS(S), cAMPS(R), and 3'-NH-cAMP[ or had no effect on cell aggregation [cAMPN(CH3)2(S) and cAMPN(CH3)2(R)]. cAMP analog 3'-NH-cAMP prevented cell aggregation by the inhibition of chemotaxis, whereas cell locomotion was not affected. Although we cannot provide a satisfactory explantation for these observations, our data suggest that occupation and activation of the cAMP receptors do not always induced a chemotactic response.

  18. Analysis of the Microprocessor in Dictyostelium: The Role of RbdB, a dsRNA Binding Protein.

    Science.gov (United States)

    Meier, Doreen; Kruse, Janis; Buttlar, Jann; Friedrich, Michael; Zenk, Fides; Boesler, Benjamin; Förstner, Konrad U; Hammann, Christian; Nellen, Wolfgang

    2016-06-01

    We identified the dsRNA binding protein RbdB as an essential component in miRNA processing in Dictyostelium discoideum. RbdB is a nuclear protein that accumulates, together with Dicer B, in nucleolar foci reminiscent of plant dicing bodies. Disruption of rbdB results in loss of miRNAs and accumulation of primary miRNAs. The phenotype can be rescued by ectopic expression of RbdB thus allowing for a detailed analysis of domain function. The lack of cytoplasmic dsRBD proteins involved in miRNA processing, suggests that both processing steps take place in the nucleus thus resembling the plant pathway. However, we also find features e.g. in the domain structure of Dicer which suggest similarities to animals. Reduction of miRNAs in the rbdB- strain and their increase in the Argonaute A knock out allowed the definition of new miRNAs one of which appears to belong to a new non-canonical class.

  19. Kin Discrimination in Dictyostelium Social Amoebae.

    Science.gov (United States)

    Strassmann, Joan E

    2016-05-01

    Evolved cooperation is stable only when the benefactor is compensated, either directly or through its relatives. Social amoebae cooperate by forming a mobile multicellular body in which, about 20% of participants ultimately die to form a stalk. This benefits the remaining individuals that become hardy spores at the top of the stalk, together making up the fruiting body. In studied species with stalked migration, P. violaceum, D. purpureum, and D. giganteum, sorting based on clone identity occurs in laboratory mixes, maintaining high relatedness within the fruiting bodies. D. discoideum has unstalked migration, where cell fate is not fixed until the slug forms a fruiting body. Laboratory mixes show some degree of both spatial and genotype-based sorting, yet most laboratory fruiting bodies remain chimeric. However, wild fruiting bodies are made up mostly of clonemates. A genetic mechanism for sorting is likely to be cell adhesion genes tgrB1 and tgrC1, which bind to each other. They are highly variable, as expected for a kin discrimination gene. It is a puzzle that these genes do not cause stronger discrimination between mixed wild clones, but laboratory conditions or strong sorting early in the social stage diminished by later slug fusion could be explanations. © 2016 The Author Journal of Eukaryotic Microbiology © 2016 International Society of Protistologists.

  20. Phospholipase Cδ regulates germination of Dictyostelium spores

    Directory of Open Access Journals (Sweden)

    Van Haastert Peter JM

    2001-12-01

    Full Text Available Abstract Background Many eukaryotes, including plants and fungi make spores that resist severe environmental stress. The micro-organism Dictyostelium contains a single phospholipase C gene (PLC; deletion of the gene has no effect on growth, cell movement and differentiation. In this report we show that PLC is essential to sense the environment of food-activated spores. Results Plc-null spores germinate at alkaline pH, reduced temperature or increased osmolarity, conditions at which the emerging amoebae can not grow. In contrast, food-activated wild-type spores return to dormancy till conditions in the environment allow growth. The analysis of inositol 1,4,5-trisphosphate (IP3 levels and the effect of added IP3 uncover an unexpected mechanism how PLC regulates spore germination: i deletion of PLC induces the enhanced activity of an IP5 phosphatase leading to high IP3 levels in plc-null cells; ii in wild-type spores unfavourable conditions inhibit PLC leading to a reduction of IP3 levels; addition of exogenous IP3 to wild-type spores induces germination at unfavourable conditions; iii in plc-null spores IP3 levels remain high, also at unfavourable environmental conditions. Conclusions The results imply that environmental conditions regulate PLC activity and that IP3 induces spore germination; the uncontrolled germination of plc-null spores is not due to a lack of PLC activity but to the constitutive activation of an alternative IP3-forming pathway.

  1. Dicty_cDB: CHR730 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ( AC117075 |pid:none) Dictyostelium discoideum chromoso... 161 2e-38 AC117176_58( AC117176 |pid:none) Dictyo...stelium discoideum chromoso... 154 2e-36 AC116982_20( AC116982 |pid:none) Dictyostelium discoideum chromoso...... 151 2e-35 AC116982_23( AC116982 |pid:none) Dictyostelium discoideum chromoso...... 147 2e-34 AC116963_16( AC116963 |pid:none) Dictyostelium discoideum chromoso... 122 6e-27 AC116963_19( AC1...16963 |pid:none) Dictyostelium discoideum chromoso... 122 1e-26 AC116305_75( AC116305 |pid:none) Dictyostelium discoideum chromoso...

  2. Dicty_cDB: Contig-U14619-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Dictyostelium discoideum chromoso... 128 1e-28 AC116982_23( AC116982 |pid:none) D...ictyostelium discoideum chromoso... 125 1e-27 (Q54ED6) RecName: Full=Probable polyketide synthase 41; ... 12...e) Dictyostelium discoideum chromoso... 118 2e-25 AC116982_72( AC116982 |pid:none) Dictyostelium discoideum chromoso...... 117 3e-25 AC117075_22( AC117075 |pid:none) Dictyostelium discoideum chromoso......6963 |pid:none) Dictyostelium discoideum chromoso... 104 3e-21 AC116963_19( AC116963 |pid:none) Dictyostelium discoideum chromoso...

  3. Dicty_cDB: AFJ179 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available _58( AC117176 |pid:none) Dictyostelium discoideum chromoso... 100 4e-20 AC116982_23( AC116982 |pid:none) Dic...tyostelium discoideum chromoso... 100 6e-20 AC116982_20( AC116982 |pid:none) Dictyostelium discoideum chromoso...... 93 9e-18 AC116982_28( AC116982 |pid:none) Dictyostelium discoideum chromoso...... 91 4e-17 AC117075_22( AC117075 |pid:none) Dictyostelium discoideum chromoso... 89 1e-16 AC116305_81( AC1...16305 |pid:none) Dictyostelium discoideum chromoso... 87 5e-16 AC116963_16( AC116963 |pid:none) Dictyostelium discoideum chromoso...

  4. Dicty_cDB: SLK832 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 075_22( AC117075 |pid:none) Dictyostelium discoideum chromoso... 100 1e-20 AC116982_22( AC116982 |pid:none) ...Dictyostelium discoideum chromoso... 59 7e-08 AC116982_19( AC116982 |pid:none) Dictyostelium discoideum chromoso...... 56 3e-07 AC116963_15( AC116963 |pid:none) Dictyostelium discoideum chromoso...... 55 1e-06 AC116982_72( AC116982 |pid:none) Dictyostelium discoideum chromoso... 51 1e-05 AC117176_58( A...C117176 |pid:none) Dictyostelium discoideum chromoso... 50 2e-05 AC116982_27( AC116982 |pid:none) Dictyostelium discoideum chromoso..

  5. Phospholipase C delta regulates germination of Dictyostelium spores

    NARCIS (Netherlands)

    Van Dijken, P.; Van Haastert, PJM

    2001-01-01

    Background: Many eukaryotes including plants and fungi make spores that resist severe environmental stress. The micro-organism Dictyostelium contains a single phospholipase C gene (PLC); deletion of the gene has no effect on growth cell movement and differentiation. In this report we show that PLC

  6. Phospholipase C delta regulates germination of Dictyostelium spores

    NARCIS (Netherlands)

    Van Dijken, P.; Van Haastert, PJM

    2001-01-01

    Background: Many eukaryotes including plants and fungi make spores that resist severe environmental stress. The micro-organism Dictyostelium contains a single phospholipase C gene (PLC); deletion of the gene has no effect on growth cell movement and differentiation. In this report we show that PLC i

  7. Characterization of two unusual guanylyl cyclases from Dictyostelium

    NARCIS (Netherlands)

    Roelofs, Jeroen; Haastert, Peter J.M. van

    2002-01-01

    Guanylyl cyclase A (GCA) and soluble guanylyl cyclase (sGC) encode GCs in Dictyostelium and have a topology similar to 12-transmembrane and soluble adenylyl cyclase, respectively. We demonstrate that all detectable GC activity is lost in a cell line in which both genes have been inactivated. Cell li

  8. Biochemistry and genetics of inositol phosphate metabolism in Dictyostelium

    NARCIS (Netherlands)

    vanHaastert, PJM; van Dijken, P.

    1997-01-01

    Biochemical and genetic data on the metabolism of inositol phosphates in the microorganism Dictyostelium are combined in a scheme composed of in five subroutes. The first subroute is the inositol cycle as found in other organisms:inositol is incorporated into phospholipids that are hydrolysed by PLC

  9. Dicty_cDB: VHF189 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available e) Dictyostelium discoideum chromoso... 140 4e-32 AC116960_61( AC116960 |pid:none...) Dictyostelium discoideum chromoso... 63 1e-08 AC116956_34( AC116956 |pid:none) Dictyostelium discoideum chromoso...... 59 2e-07 AC116982_41( AC116982 |pid:none) Dictyostelium discoideum chromoso... 59 3e-07 AC116967_7...elium discoideum chromoso... 52 2e-05 AC116920_24( AC116920 |pid:none) Dictyostelium discoideum chromoso... ...52 2e-05 AC117081_39( AC117081 |pid:none) Dictyostelium discoideum chromoso... 52 2e-05 AC117081_43( AC11708

  10. Functional overlap of the dictyostelium RasG, RasD and RasB proteins.

    Science.gov (United States)

    Khosla, M; Spiegelman, G B; Insall, R; Weeks, G

    2000-04-01

    Disruption of the rasG gene in Dictyostelium discoideum results in several distinct phenotypes: a defect in cytokinesis, reduced motility and reduced growth. Reintroduction of the rasG gene restores all of the properties of the rasG(-) cells to those of the wild type. To determine whether the defects are due to impaired interactions with a single or multiple downstream effectors, we tested the ability of the highly related but non identical Dictyostelium ras genes, rasD and rasB, to rescue the defects. Introduction of the rasD gene under the control of the rasG promoter into rasG null (rasG(-)) cells corrected all phenotypes except the motility defect, suggesting that motility is regulated by a RasG mediated pathway that is different to those regulating growth or cytokinesis. Western blot analysis of RasD protein levels revealed that vegetative rasG(- )cells contained considerably more protein than the parental AX-3 cells, suggesting that RasD protein levels are negatively regulated in vegetative cells by RasG. The level of RasD was enhanced when the rasD gene was introduced under the control of the rasG promoter, and this increase in protein is presumably responsible for the reversal of the growth and cytokinesis defects of the rasG(- )cells. Thus, RasD protein levels are controlled by the level of RasG, but not by the level of RasD. Introduction of the rasB gene under the control of the rasG promoter into rasG(-) cells produced a complex phenotype. The transformants were extremely small and mononucleate and exhibited enhanced motility. However, the growth of these cells was considerably slower than the growth of the rasG(-) cells, suggesting the possibility that high levels of RasB inhibit an essential process. This was confirmed by expressing rasB in wild-type cells; the resulting transformants exhibited severely impaired growth. When RasB protein levels were determined by western blot analysis, it was found that levels were higher in the rasG(- )cells than they

  11. On the Swimming of \\textit{Dictyostelium} amoebae

    CERN Document Server

    Bae, Albert

    2010-01-01

    Traditionally, the primary mode for locomotion of amoeboid cells was thought to be crawling on a substrate. Recently, it has been experimentally shown that \\textit{Dictostelium} amoeba and neutrophils can also swim in a directed fashion. The mechanisms for amoeboid crawling and swimming were hypothesized to be similar. In this letter, we show that the shape changes generated by a crawling \\textit{D. discoideum} cell are consistent with swimming.

  12. Dicty_cDB: VSH844 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ictyostelium discoideum cDNA clone:ddv50m11, 5' ... 942 0.0 2 ( C23686 ) Dictyostelium discoideum gamete cDN...7 ) Dictyostelium discoideum cDNA clone:ddv50m11, 3' ... 942 0.0 2 ( AU265127 ) Dictyostelium discoideum veg

  13. Dicty_cDB: VSI126 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 268192 ) Dictyostelium discoideum vegetative cDNA clone:VS... 418 e-113 1 ( BJ442592 ) Dictyostelium discoideum cDNA clone:ddv50...lium discoideum cDNA clone:ddv50m22, 3' ... 400 e-107 1 ( BJ441082 ) Dictyostelium discoideum cDNA clone:ddv

  14. Dicty_cDB: VHF201 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 442499 ) Dictyostelium discoideum cDNA clone:ddv50g01, 3' ... 1352 0.0 1 ( BJ442525 ) Dictyostelium discoideum cDNA clone:ddv50...um discoideum cDNA clone:ddc55m02, 3' ... 1193 0.0 2 ( BJ442653 ) Dictyostelium discoideum cDNA clone:ddv50f

  15. Dicty_cDB: VHJ861 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ostelium discoideum cDNA clone:ddv50j16, 3' ... 1475 0.0 1 ( BJ446334 ) Dictyostelium discoideum cDNA clone:...J442764 ) Dictyostelium discoideum cDNA clone:ddv50l21, 3' ... 1467 0.0 1 ( BJ442731 ) Dictyostelium discoideum cDNA clone:ddv50

  16. Dicty_cDB: VHJ654 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 674 ) Dictyostelium discoideum cDNA clone:ddv50k14, 3' ... 1457 0.0 1 ( BJ442828 ) Dictyostelium discoideum ...8 0.0 1 ( BJ442759 ) Dictyostelium discoideum cDNA clone:ddv50k20, 3' ... 1392 0....discoideum cDNA clone:ddv57b24, 3' ... 1390 0.0 1 ( BJ442507 ) Dictyostelium discoideum cDNA clone:ddv50h05,

  17. Dicty_cDB: Contig-U15761-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available AGG AATTATATATACAATAAAAAACAAAAAACAAAA Gap gap included Contig length 4873 Chromosome number (1..6, M) - Chromo...ykw*ctkscein*fnyth fkiiwciwtfw*****ytiidisnysskw*kytnak**wysfikcrwindysrfirftif k... AC116984 ) Dictyostelium discoideum chromosome 2 map 2567470... 1322 0.0 2 ( BJ336402 ) Dictyostelium disco...-50 1 ( AC115683 ) Dictyostelium discoideum chromosome 2 map complem... 40 7e-13 13 ( AC116305 ) Dictyostelium discoideum chromo...some 2 map 1005175... 36 2e-08 17 ( AC116986 ) Dictyostelium discoideum chromo

  18. Dicty_cDB: SLA476 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available clone SLA476. 1154 0.0 1 ( BJ442525 ) Dictyostelium discoideum cDNA clone:ddv50l...9 ) Dictyostelium discoideum cDNA clone:ddv50g01, 3' ... 1104 0.0 2 ( BJ438430 ) Dictyostelium discoideum cD... BJ442653 ) Dictyostelium discoideum cDNA clone:ddv50f18, 3' ... 1011 0.0 3 ( BJ385501 ) Dictyostelium disco

  19. Dicty_cDB: VHM378 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available alignments: (bits) Value AC116963_42( AC116963 |pid:none) Dictyostelium discoideum chromoso... 65 2e-09 AC1...16920_20( AC116920 |pid:none) Dictyostelium discoideum chromoso... 63 4e-09 AC116920_24( AC116920 |pid:none)... Dictyostelium discoideum chromoso... 61 1e-08 AC116920_25( AC116920 |pid:none) D...ictyostelium discoideum chromoso... 62 1e-08 AC116982_41( AC116982 |pid:none) Dictyostelium discoideum chromoso...... 56 1e-06 AC117081_43( AC117081 |pid:none) Dictyostelium discoideum chromoso... 54 5e-06 AC116984_28(

  20. Dicty_cDB: VHD138 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available gnificant alignments: (bits) Value AC117075_41( AC117075 |pid:none) Dictyostelium discoideum chromoso...... 157 8e-38 AC116960_61( AC116960 |pid:none) Dictyostelium discoideum chromoso... 75 9...e-13 AC116982_41( AC116982 |pid:none) Dictyostelium discoideum chromoso... 74 1e-12 AC116956_34( AC116956 |p...id:none) Dictyostelium discoideum chromoso... 72 8e-12 AC116920_24( AC116920 |pid...:none) Dictyostelium discoideum chromoso... 70 2e-11 AC117081_39( AC117081 |pid:none) Dictyostelium discoideum chromoso...

  1. Dicty_cDB: VSG790 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Sequences producing significant alignments: (bits) Value AC116963_42( AC116963 |pid:none) Dictyostelium discoideum chromoso...... 74 2e-12 AC116920_20( AC116920 |pid:none) Dictyostelium discoideum chromoso... 72 7e-12 A...C116920_24( AC116920 |pid:none) Dictyostelium discoideum chromoso... 70 2e-11 AC116920_25( AC116920 |pid:non...e) Dictyostelium discoideum chromoso... 68 9e-11 AC116982_41( AC116982 |pid:none)... Dictyostelium discoideum chromoso... 60 2e-08 AC117081_43( AC117081 |pid:none) Dictyostelium discoideum chromoso...

  2. Dicty_cDB: SHH616 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ant alignments: (bits) Value AC116982_20( AC116982 |pid:none) Dictyostelium discoideum chromoso... 128 1e-28... AC116982_23( AC116982 |pid:none) Dictyostelium discoideum chromoso... 125 1e-27 AC117176_58( AC117176 |pid:...none) Dictyostelium discoideum chromoso... 118 2e-25 AC116982_72( AC116982 |pid:n...one) Dictyostelium discoideum chromoso... 117 3e-25 AC117075_22( AC117075 |pid:none) Dictyostelium discoideum chromoso...... 109 8e-23 AC116963_16( AC116963 |pid:none) Dictyostelium discoideum chromoso... 104 3e-21 AC11

  3. Dicty_cDB: VHQ117 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ng significant alignments: (bits) Value AC116963_42( AC116963 |pid:none) Dictyostelium discoideum chromoso...... 65 1e-09 AC116920_20( AC116920 |pid:none) Dictyostelium discoideum chromoso... 63 3e-09 AC116920_25( AC116...920 |pid:none) Dictyostelium discoideum chromoso... 62 9e-09 AC116920_24( AC116920 |pid:none) Dictyostelium discoideum chromoso...... 61 1e-08 AC116982_41( AC116982 |pid:none) Dictyostelium discoideum chromoso...... 55 1e-06 AC117081_43( AC117081 |pid:none) Dictyostelium discoideum chromoso... 54 2e-06

  4. Dicty_cDB: VHM207 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available lignments: (bits) Value AC116963_42( AC116963 |pid:none) Dictyostelium discoideum chromoso...... 167 2e-40 AC117075_64( AC117075 |pid:none) Dictyostelium discoideum chromoso... 155 1e-36 AC116...960_61( AC116960 |pid:none) Dictyostelium discoideum chromoso... 154 1e-36 AC116982_41( AC116982 |pid:none) ...Dictyostelium discoideum chromoso... 152 9e-36 AC117081_43( AC117081 |pid:none) D...ictyostelium discoideum chromoso... 144 3e-33 AC116956_34( AC116956 |pid:none) Dictyostelium discoideum chromoso...

  5. 聚氨酯泡沫半固定化培养盘基网柄菌%Immobilized cultivation of Dictyostelium discoideum with polyurethane foam

    Institute of Scientific and Technical Information of China (English)

    梁兴超; 卢英华; 陈杰; 徐志南

    2007-01-01

    研究了聚氨酯泡沫应用于固定化盘基网柄菌的可行性,发现以简单处理过的聚氨酯泡沫为载体,能够高效实现盘基网柄菌的固定化培养.考察了载体粒径大小、载体量和摇床转速等对固定化培养的影响,在优化的培养条件和固定化条件下,盘基网柄菌的最大细胞密度是悬浮培养的2~4倍.

  6. High Cell Density Cultivation of Dictyostelium discoideum in Conventional Bioreactor%发酵罐高密度培养盘基网柄菌

    Institute of Scientific and Technical Information of China (English)

    陈祥仁; 黄霄红; 徐宝多; 卢英华

    2006-01-01

    利用SIH合成培养基,在7 L发酵罐培养盘基网柄菌.培养147 h后,细胞密度达到4.0×107 mL-1,为在复杂培养基上所能达到的细胞密度的2~4倍.培养过程中葡萄糖的消耗量为6.7 g/L,产氨浓度达0.88 g/L.对培养基中的氨基酸分析表明,赖氨酸、色氨酸、甲硫氨酸和苯丙氨酸消耗较快, 显示SIH培养基的氨基酸成分还可进一步优化.采用基于Monod生长动力学的半经验模型可很好模拟细胞生长和底物消耗,并估计出动力学参数μmax = 0.115 h-1, Nmax = 6.0×107 mL-1.本研究为进一步优化合成培养基和为利用这一新型真核表达系统大规模生产重组异源蛋白奠定了基础.

  7. Kinetics and concentration dependency of cAMP-induced desensitization of a subpopulation of surface cAMP receptors in Dictyostelium discoideum

    Energy Technology Data Exchange (ETDEWEB)

    Van Haastert, P.J.M.

    1987-11-17

    Extracellular cAMP induces the rapid activation of guanylate cyclase, which adapts within 10 s to constant cAMP concentrations. A new response can be induced either by a higher cAMP concentration or by the same cAMP concentration at some time (t/sub 1/2/ = 90 s) after removal of the previous stimulus. Stimulation of guanylate cyclase is supposed to be mediated by a subpopulation of cell surface cAMP receptors (B-sites). These sites can exist in three states, B/sup F/, B/sup S/, and B/sup SS/, which interconvert in a cAMP and guanine nucleotide dependent manner. It has been proposed that the transition of B/sup S/ to B/sup SS/ represents the activation of a guanine nucleotide regulatory protein. Binding of (/sup 3/H)cAMP to these sites was measured after a short preincubation with an identical concentration of nonradioacative cAMP. (/sup 3/H)cAMP could still bind to B/sup F/ and B/sup S/, but not to B/sup SS/, indicating that the transition of B/sup S/ to B/sup SS/ is blocked by the preincubation with cAMP. This blockade was rapid and showed first-order kinetics with t/sub 1/2/ = 4 s. A half-maximal blockade was induced by 0.7 nM cAMP; at this concentration on 5% of the B-sites are occupied with cAMP. The blockade of the transition of B/sup S/ to B/sup SS/ was released by two conditions: (i) When the concentration of cAMP was increased, the blockade was released within a few seconds. (ii) When cAMP was removed, the blockade was released slowly with t/sub 1/2/ = 90 s. Finally, cAMP did not induce the blockade under conditions where guanylate cyclase did not adapt, i.e., at 0/sup 0/C and in cells starved for 2 h or less. These results suggest that the interaction of cAMP with the B-sites induces a rapid and reversible blockade of the terminal step in the generation of an active G-protein and that this blockade could be the molecular basis of adaptation of guanylate cyclase.

  8. Differential Role of Poly(ADP-ribose polymerase in D. discoideum growth and development

    Directory of Open Access Journals (Sweden)

    Begum Rasheedunnisa

    2011-03-01

    Full Text Available Abstract Background Poly(ADP-ribose polymerase is evolutionarily conserved as a responder to various forms of stress. Though PARP's role in cell death is well addressed, its role in development and multicellularity is still an enigma. We have previously reported the role of PARP in oxidative stress induced delayed development of D. discoideum. Results In the current study we highlight the involvement of PARP during D. discoideum development. Oxidative stress affects expression of aca and cAR1 thus affecting aggregation. Although parp expression is not affected during oxidative stress but it is involved during normal development as confirmed by our PARP down-regulation studies. Constitutive PARP down-regulation resulted in blocked development while no effect was observed on D. discoideum growth. Interestingly, stage specific PARP down-regulation arrested development at the slug stage. Conclusion These results emphasize that PARP is essential for complex differentiation and its function may be linked to multicellularity. This is the first report where the involvement of PARP during normal multicellular development in D. discoideum, an ancient eukaryote, is established which could be of evolutionary significance. Thus our study adds one more role to the multitasking function of PARP.

  9. Exploitation of other social amoebae by Dictyostelium caveatum.

    Science.gov (United States)

    Nizak, Clément; Fitzhenry, Robert J; Kessin, Richard H

    2007-02-14

    Dictyostelium amoebae faced with starvation trigger a developmental program during which many cells aggregate and form fruiting bodies that consist of a ball of spores held aloft by a thin stalk. This developmental strategy is open to several forms of exploitation, including the remarkable case of Dictyostelium caveatum, which, even when it constitutes 1/10(3) of the cells in an aggregate, can inhibit the development of the host and eventually devour it. We show that it accomplishes this feat by inhibiting a region of cells, called the tip, which organizes the development of the aggregate into a fruiting body. We use live-cell microscopy to define the D. caveatum developmental cycle and to show that D. caveatum amoebae have the capacity to ingest amoebae of other Dictyostelid species, but do not attack each other. The block in development induced by D. caveatum does not affect the expression of specific markers of prespore cell or prestalk cell differentiation, but does stop the coordinated cell movement leading to tip formation. The inhibition mechanism involves the constitutive secretion of a small molecule by D. caveatum and is reversible. Four Dictyostelid species were inhibited in their development, while D. caveatum is not inhibited by its own compound(s). D. caveatum has evolved a predation strategy to exploit other members of its genus, including mechanisms of developmental inhibition and specific phagocytosis.

  10. Exploitation of other social amoebae by Dictyostelium caveatum.

    Directory of Open Access Journals (Sweden)

    Clément Nizak

    Full Text Available Dictyostelium amoebae faced with starvation trigger a developmental program during which many cells aggregate and form fruiting bodies that consist of a ball of spores held aloft by a thin stalk. This developmental strategy is open to several forms of exploitation, including the remarkable case of Dictyostelium caveatum, which, even when it constitutes 1/10(3 of the cells in an aggregate, can inhibit the development of the host and eventually devour it. We show that it accomplishes this feat by inhibiting a region of cells, called the tip, which organizes the development of the aggregate into a fruiting body. We use live-cell microscopy to define the D. caveatum developmental cycle and to show that D. caveatum amoebae have the capacity to ingest amoebae of other Dictyostelid species, but do not attack each other. The block in development induced by D. caveatum does not affect the expression of specific markers of prespore cell or prestalk cell differentiation, but does stop the coordinated cell movement leading to tip formation. The inhibition mechanism involves the constitutive secretion of a small molecule by D. caveatum and is reversible. Four Dictyostelid species were inhibited in their development, while D. caveatum is not inhibited by its own compound(s. D. caveatum has evolved a predation strategy to exploit other members of its genus, including mechanisms of developmental inhibition and specific phagocytosis.

  11. The life cycle of Dictyostelium magnum%大网柄菌 Dictyostelium magnum 生活史的研究

    Institute of Scientific and Technical Information of China (English)

    孙金月; 刘朴; 李玉

    2011-01-01

    The whole process of the life cycle of Dictyostelium magnum was observed microscopically on the bi-concavity slide and the water agar. A complete life cycle of D. magnum needs 2-3d duration. The characteristics of spores, myxamoebae, aggregation,pseudoplasmodium, ascent, sorocarp and spore release were observed.%为了了解网柄菌生活史循环的整个过程,显微观察了大网柄菌 Dictyostelium magnum 在双凹载玻片及水琼脂培养基上的完整生长循环,记录了大网柄菌生活史中各阶段,即孢子、黏变形体、集群、假原质团、拔项、孢堆果及再次释放孢子的显著特征,整个生活循环历时2-3d.

  12. Postaggregative Differentiation Induction by Cyclic AMP in Dictyostelium : Intracellular Transduction Pathway and Requirement for Additional Stimuli

    NARCIS (Netherlands)

    Schaap, Pauline; Lookeren Campagne, Michiel M. van; Driel, Roel van; Spek, Wouter; Haastert, Peter J.M. van; Pinas, Johan

    1986-01-01

    Cyclic AMP induces postaggregative differentiation in aggregation competent cells of Dictyostelium by interacting with cell surface cAMP receptors. We investigated the transduction pathway of this response and additional requirements for the induction of postaggregative differentiation. Optimal indu

  13. Dicty_cDB: VFN619 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available gnificant alignments: (bits) Value U57081_2( U57081 |pid:none) Dictyostelium discoideum Tdd-4 transpo...... 165 4e-40 U57081_1( U57081 |pid:none) Dictyostelium discoideum Tdd-4 transpo... 165

  14. Dicty_cDB: VFJ102 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ts) Value N ( M19469 ) Dictyostelium discoideum 109 gene 3, complete cds. 105 9e-26 2 ( U48706 ) Dictyostelium discoideum small aggre...gate formation ... 105 9e-26 2 ( BJ411890 ) Dictyosteliu

  15. Dicty_cDB: AFG687 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ant alignments: (bits) Value N AF305060 |AF305060.1 Dictyostelium discoideum Wiscott...n Score E Sequences producing significant alignments: (bits) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott

  16. Dicty_cDB: AFF743 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Sequences producing significant alignments: (bits) Value N AF305060 |AF305060.1 Dictyostelium discoideum Wiscott...oducing significant alignments: (bits) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott

  17. Dicty_cDB: CFC194 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available equences producing significant alignments: (bits) Value N AF305060 |AF305060.1 Dictyostelium discoideum Wiscott...nts: (bits) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott

  18. Dicty_cDB: AFE360 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available t alignments: (bits) Value N AF305060 |AF305060.1 Dictyostelium discoideum Wiscott-Aldrich syndrome protein ...(bits) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott-A..

  19. Dicty_cDB: SFC807 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available icant alignments: (bits) Value N AF305060 |AF305060.1 Dictyostelium discoideum Wiscott-Aldrich syndrome prot...ng significant alignments: (bits) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott

  20. LagC is required for cell-cell interactions that are essential for cell-type differentiation in Dictyostelium.

    Science.gov (United States)

    Dynes, J L; Clark, A M; Shaulsky, G; Kuspa, A; Loomis, W F; Firtel, R A

    1994-04-15

    Strain AK127 is a developmental mutant of Dictyostelium discoideum that was isolated by restriction enzyme-mediated integration (REMI). Mutant cells aggregate normally but are unable to proceed past the loose aggregate stage. The cloned gene, lagC (loose aggregate C), encodes a novel protein of 98 kD that contains an amino-terminal signal sequence and a putative carboxy-terminal transmembrane domain. The mutant strain AK127 shows no detectable lagC transcript upon Northern analysis, indicating that the observed phenotype is that of a null allele. Expression of the lagC cDNA in AK127 cells complements the arrest at the loose aggregate stage, indicating that the mutant phenotype results from disruption of the lagC gene. In wild-type cells, lagC mRNA is induced at the loose aggregate stage and is expressed through the remainder of development. lagC- null cells aggregate but then disaggregate and reaggregate to form small granular mounds. Mature spores are produced at an extremely low efficiency (rasD and CP2 and do not express the DIF-induced prestalk-specific gene ecmA or the cAMP-induced prespore-specific gene SP60 to significant levels. In chimeric organisms resulting from the coaggregation of lagC- null and wild-type cells, cell-type-specific gene expression is rescued in the lagC- null cells; however, lagC- prespore cells are localized to the posterior of the prespore region and do not form mature spores, suggesting that LagC protein has both no cell-autonomous and cell-autonomous functions. Overexpression of lagC from an actin promoter in both wild-type and lagC- cells causes a delay at the tight aggregate stage, the first stage requiring LagC activity. These results suggest that the LagC protein functions as a nondiffusible cell-cell signaling molecule that is required for multicellular development.

  1. Dictyostelium RasD is required for normal phototaxis, but not differentiation

    OpenAIRE

    Wilkins, Andrew; Khosla, Meenal; Fraser, Derek J; Spiegelman, George B.; Fisher, Paul R.; Weeks, Gerald; Insall, Robert H.

    2000-01-01

    RasD, a Dictyostelium homolog of mammalian Ras, is maximally expressed during the multicellular stage of development. Normal Dictyostelium aggregates are phototactic and thermotactic, moving towards sources of light and heat with great sensitivity. We show that disruption of the gene for rasD causes a near-total loss of phototaxis and thermotaxis in mutant aggregates, without obvious effects on undirected movement. Previous experiments had suggested important roles for RasD in development and...

  2. Dicty_cDB: SSD703 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available nments: (bits) Value AC116982_41( AC116982 |pid:none) Dictyostelium discoideum chromoso...... 74 2e-12 AC116963_42( AC116963 |pid:none) Dictyostelium discoideum chromoso... 59 7e-11 AC116920_2...0( AC116920 |pid:none) Dictyostelium discoideum chromoso... 57 7e-11 AC116967_8( AC116967 |pid:none) Dictyos...elium discoideum chromoso... 53 1e-08 AC117075_65( AC117075 |pid:none) Dictyostelium discoideum chromoso... ...50 2e-08 AC116920_24( AC116920 |pid:none) Dictyostelium discoideum chromoso... 60 6e-08 AC116920_25( AC11692

  3. Dicty_cDB: VHN217 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 25 ) Dictyostelium discoideum cDNA clone:ddv50l04, 3' ... 1094 0.0 3 ( BJ442653 )... Dictyostelium discoideum cDNA clone:ddv50f18, 3' ... 1076 0.0 4 ( BJ445359 ) Dictyostelium discoideum cDNA ...clone:ddv59a09, 3' ... 1007 0.0 3 ( BJ442499 ) Dictyostelium discoideum cDNA clone:ddv50g01, 3' ... 999 0.0

  4. Dicty_cDB: VHJ523 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available s) Value N ( BJ442531 ) Dictyostelium discoideum cDNA clone:ddv50m05, 3' ... 1772 0.0 1 ( BJ443457 ) Dictyos...v31j09, 3' ... 1655 0.0 2 ( BJ442583 ) Dictyostelium discoideum cDNA clone:ddv50g...7 ) Dictyostelium discoideum cDNA clone:ddv50o17, 3' ... 1628 0.0 2 ( BJ442656 ) Dictyostelium discoideum cDNA clone:ddv50

  5. Dicty_cDB: VHN889 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available , 3' ... 1463 0.0 1 ( BJ442773 ) Dictyostelium discoideum cDNA clone:ddv50m24, 3'... ... 1463 0.0 1 ( BJ442764 ) Dictyostelium discoideum cDNA clone:ddv50l21, 3' ... 1463 0.0 1 ( BJ442731 ) Di...ctyostelium discoideum cDNA clone:ddv50e24, 3' ... 1463 0.0 1 ( BJ442218 ) Dictyostelium discoideum cDNA clo

  6. Dicty_cDB: VHJ736 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ces producing significant alignments: (bits) Value N ( BJ442585 ) Dictyostelium discoideum cDNA clone:ddv50h...Dictyostelium discoideum cDNA clone:ddv17m03, 3' ... 1162 0.0 1 ( BJ423840 ) Dictyostelium discoideum cDNA clone:ddv50...g16, 5' ... 105 3e-18 1 ( BJ423768 ) Dictyostelium discoideum cDNA clone:ddv50h09, 5' ... 105 3e-1

  7. Dicty_cDB: VHJ558 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ificant alignments: (bits) Value N ( BJ442636 ) Dictyostelium discoideum cDNA clone:ddv50c15, 3' ... 1296 0.... ) Dictyostelium discoideum cDNA clone:ddv50k22, 3' ... 1219 0.0 2 ( BJ441840 ) Dictyostelium discoideum cDN...deum cDNA clone:dda54e23, 3' ... 1211 0.0 2 ( BJ423817 ) Dictyostelium discoideum cDNA clone:ddv50c15, 5' ..

  8. Dicty_cDB: VHJ530 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available BJ443368 ) Dictyostelium discoideum cDNA clone:ddv52o18, 3' ... 1451 0.0 1 ( BJ442687 ) Dictyostelium discoideum cDNA clone:ddv50...m18, 3' ... 1451 0.0 1 ( BJ442596 ) Dictyostelium discoideum cDNA clone:ddv50...451 0.0 1 ( BJ442548 ) Dictyostelium discoideum cDNA clone:ddv50a11, 3' ... 1445 0.0 1 ( BJ438342 ) Dictyost

  9. Dicty_cDB: VHJ539 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ) Dictyostelium discoideum cDNA clone:ddv50m09, 3' ... 1366 0.0 1 ( BJ442759 ) D...ictyostelium discoideum cDNA clone:ddv50k20, 3' ... 1358 0.0 1 ( BJ441455 ) Dictyostelium discoideum cDNA cl... 1336 0.0 1 ( BJ442696 ) Dictyostelium discoideum cDNA clone:ddv50o16, 3' ... 1336 0.0 1 ( BJ437729 ) Dictyo

  10. Dicty_cDB: VHK322 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ) Dictyostelium discoideum cDNA clone:ddv51l05, 3' ... 1441 0.0 1 ( BJ442780 ) Dictyostelium discoideum cDNA clone:ddv50...o20, 3' ... 1441 0.0 1 ( BJ442687 ) Dictyostelium discoideum cDNA clone:ddv50...m18, 3' ... 1441 0.0 1 ( BJ442548 ) Dictyostelium discoideum cDNA clone:ddv50a11, 3' ... 1441 0.0 1

  11. Dicty_cDB: VHJ814 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available J442525 ) Dictyostelium discoideum cDNA clone:ddv50l04, 3' ... 1501 0.0 1 ( BJ437...847 ) Dictyostelium discoideum cDNA clone:ddv35f17, 3' ... 1320 0.0 2 ( BJ442499 ) Dictyostelium discoideum cDNA clone:ddv50...g01, 3' ... 1310 0.0 2 ( BJ442653 ) Dictyostelium discoideum cDNA clone:ddv50f18, 3' ... 129

  12. Dicty_cDB: VHK888 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ... 1348 0.0 1 ( BJ442780 ) Dictyostelium discoideum cDNA clone:ddv50o20, 3' ... ...1348 0.0 1 ( BJ442687 ) Dictyostelium discoideum cDNA clone:ddv50m18, 3' ... 1348 0.0 1 ( BJ442548 ) Dictyos...telium discoideum cDNA clone:ddv50a11, 3' ... 1348 0.0 1 ( BJ441725 ) Dictyostelium discoideum cDNA clone:dd

  13. Gene : CBRC-ACAR-01-0852 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available 187776 [Dictyostelium discoideum AX4] 2e-04 41% MSLQCPYIIIIIIIIIIIIIIIIYTHTQHNTTTHNNDVEHISPLANLIIIIIIIIIKQQQQQQRCWHISPLANL...IIIIIIIIIKQQQQQQQQQQRCWHISPLANLIIIIIIIIIKQQQQQQQQRCWHISPLANLIIIIIIIIIKQQQQRCWHISPLANL...IIIIIIIIIKQQQQQRCWHISPLANLIIIIIIIIIKQQQQQRCWHISPLANLIIIIIIIIIIIIIKLRFANCKRPPYWDLHASSENTSHSPRHLGSVRLVIL ...

  14. Dicty_cDB: Contig-U13443-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available lignments: (bits) Value N ( AF305060 ) Dictyostelium discoideum Wiscott-Aldrich syndrome... 529 0.0 10 ( BJ3... AF305060 ) Dictyostelium discoideum Wiscott-Aldrich syndrome protein (wasA) gene...icant alignments: (bits) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott...0_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott-Aldrich syndrome protein (wasA) gene, complete cds

  15. An evolutionarily significant unicellular strategy in response to starvation in Dictyostelium social amoebae [v2; ref status: indexed, http://f1000r.es/4kb

    Directory of Open Access Journals (Sweden)

    Darja Dubravcic

    2014-12-01

    Full Text Available The social amoeba Dictyostelium discoideum is widely studied for its multicellular development program as a response to starvation. Aggregates of up to 106 cells form fruiting bodies containing (i dormant spores (~80% that can persist for months in the absence of nutrients, and (ii dead stalk cells (~20% that promote the dispersion of the spores towards nutrient-rich areas. It is often overlooked that not all cells aggregate upon starvation. Using a new quantitative approach based on time-lapse fluorescence microscopy and a low ratio of reporting cells, we have quantified this fraction of non-aggregating cells. In realistic starvation conditions, up to 15% of cells do not aggregate, which makes this third cell fate a significant component of the population-level response of social amoebae to starvation. Non-aggregating cells have an advantage over cells in aggregates since they resume growth earlier upon arrival of new nutrients, but have a shorter lifespan under prolonged starvation. We find that phenotypic heterogeneities linked to cell nutritional state bias the representation of cells in the aggregating vs. non-aggregating fractions, and thus affect population partitioning. Next, we report that the fraction of non-aggregating cells depends on genetic factors that regulate the timing of starvation, signal sensing efficiency and aggregation efficiency. In addition, interactions between clones in mixtures of non-isogenic cells affect the partitioning of each clone into both fractions. We further build a numerical model to test the evolutionary significance of the non-aggregating cell fraction. The partitioning of cells into aggregating and non-aggregating fractions is optimal in fluctuating environments with an unpredictable duration of starvation periods. Our study highlights the unicellular component of the response of social amoebae to starvation, and thus extends its evolutionary and ecological framework.

  16. Heteromeric p97/p97R155C complexes induce dominant negative changes in wild-type and autophagy 9-deficient Dictyostelium strains.

    Directory of Open Access Journals (Sweden)

    Khalid Arhzaouy

    Full Text Available Heterozygous mutations in the human VCP (p97 gene cause autosomal-dominant IBMPFD (inclusion body myopathy with early onset Paget's disease of bone and frontotemporal dementia, ALS14 (amyotrophic lateral sclerosis with or without frontotemporal dementia and HSP (hereditary spastic paraplegia. Most prevalent is the R155C point mutation. We studied the function of p97 in the social amoeba Dictyostelium discoideum and have generated strains that ectopically express wild-type (p97 or mutant p97 (p97(R155C fused to RFP in AX2 wild-type and autophagy 9 knock-out (ATG9(KO cells. Native gel electrophoresis showed that both p97 and p97(R155C assemble into hexamers. Co-immunoprecipitation studies revealed that endogenous p97 and p97(R155C-RFP form heteromers. The mutant strains displayed changes in cell growth, phototaxis, development, proteasomal activity, ubiquitinylated proteins, and ATG8(LC3 indicating mis-regulation of multiple essential cellular processes. Additionally, immunofluorescence analysis revealed an increase of protein aggregates in ATG9(KO/p97(R155C-RFP and ATG9(KO cells. They were positive for ubiquitin in both strains, however, solely immunoreactive for p97 in the ATG9(KO mutant. A major finding is that the expression of p97(R155C-RFP in the ATG9(KO strain partially or fully rescued the pleiotropic phenotype. We also observed dose-dependent effects of p97 on several cellular processes. Based on findings in the single versus the double mutants we propose a novel mode of p97 interaction with the core autophagy protein ATG9 which is based on mutual inhibition.

  17. NCBI nr-aa BLAST: CBRC-DDIS-02-0227 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-02-0227 ref|XP_643200.1| unconventional myosin heavy chain [Dictyostelium... discoideum AX4] gb|AAO51651.1| similar to Dictyostelium discoideum (Slime mold). Class VII unconventional m...yosin gb|EAL69262.1| unconventional myosin heavy chain [Dictyostelium discoideum AX4] XP_643200.1 0.0 100% ...

  18. NCBI nr-aa BLAST: CBRC-DDIS-02-0174 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-02-0174 ref|XP_643200.1| unconventional myosin heavy chain [Dictyostelium... discoideum AX4] gb|AAO51651.1| similar to Dictyostelium discoideum (Slime mold). Class VII unconventional m...yosin gb|EAL69262.1| unconventional myosin heavy chain [Dictyostelium discoideum AX4] XP_643200.1 3e-37 46% ...

  19. NCBI nr-aa BLAST: CBRC-DDIS-04-0118 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-04-0118 ref|XP_643200.1| unconventional myosin heavy chain [Dictyostelium... discoideum AX4] gb|AAO51651.1| similar to Dictyostelium discoideum (Slime mold). Class VII unconventional m...yosin gb|EAL69262.1| unconventional myosin heavy chain [Dictyostelium discoideum AX4] XP_643200.1 4e-41 28% ...

  20. NCBI nr-aa BLAST: CBRC-DDIS-02-0226 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-02-0226 ref|XP_643200.1| unconventional myosin heavy chain [Dictyostelium... discoideum AX4] gb|AAO51651.1| similar to Dictyostelium discoideum (Slime mold). Class VII unconventional m...yosin gb|EAL69262.1| unconventional myosin heavy chain [Dictyostelium discoideum AX4] XP_643200.1 0.0 100% ...

  1. NCBI nr-aa BLAST: CBRC-DDIS-01-0111 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-01-0111 ref|XP_636760.1| alkaline dihydroceramidase [Dictyostelium discoi...deum AX4] gb|AAQ98884.1| alkaline dihydroceramidase [Dictyostelium discoideum] gb|EAL63276.1| alkaline dihydroceramidase [Dictyostelium discoideum AX4] XP_636760.1 7e-59 45% ...

  2. NCBI nr-aa BLAST: CBRC-DDIS-01-0000 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-01-0000 ref|XP_636822.1| MAP kinase phosphatase [Dictyostelium discoideum... AX4] dbj|BAB12429.1| mkpA [Dictyostelium discoideum] gb|EAL63306.1| MAP kinase phosphatase [Dictyostelium discoideum AX4] XP_636822.1 7e-05 28% ...

  3. NCBI nr-aa BLAST: CBRC-DRER-16-0071 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DRER-16-0071 ref|XP_636822.1| MAP kinase phosphatase [Dictyostelium discoideum... AX4] dbj|BAB12429.1| mkpA [Dictyostelium discoideum] gb|EAL63306.1| MAP kinase phosphatase [Dictyostelium discoideum AX4] XP_636822.1 1e-38 47% ...

  4. NCBI nr-aa BLAST: CBRC-DDIS-02-0264 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-02-0264 ref|XP_636822.1| MAP kinase phosphatase [Dictyostelium discoideum... AX4] dbj|BAB12429.1| mkpA [Dictyostelium discoideum] gb|EAL63306.1| MAP kinase phosphatase [Dictyostelium discoideum AX4] XP_636822.1 3e-57 28% ...

  5. NCBI nr-aa BLAST: CBRC-DDIS-01-0161 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-01-0161 ref|XP_636822.1| MAP kinase phosphatase [Dictyostelium discoideum... AX4] dbj|BAB12429.1| mkpA [Dictyostelium discoideum] gb|EAL63306.1| MAP kinase phosphatase [Dictyostelium discoideum AX4] XP_636822.1 6e-64 29% ...

  6. NCBI nr-aa BLAST: CBRC-DDIS-02-0113 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-02-0113 ref|XP_636822.1| MAP kinase phosphatase [Dictyostelium discoideum... AX4] dbj|BAB12429.1| mkpA [Dictyostelium discoideum] gb|EAL63306.1| MAP kinase phosphatase [Dictyostelium discoideum AX4] XP_636822.1 4e-45 33% ...

  7. NCBI nr-aa BLAST: CBRC-DDIS-04-0090 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-04-0090 ref|XP_636822.1| MAP kinase phosphatase [Dictyostelium discoideum... AX4] dbj|BAB12429.1| mkpA [Dictyostelium discoideum] gb|EAL63306.1| MAP kinase phosphatase [Dictyostelium discoideum AX4] XP_636822.1 7e-50 41% ...

  8. NCBI nr-aa BLAST: CBRC-DDIS-01-0013 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-01-0013 ref|XP_636822.1| MAP kinase phosphatase [Dictyostelium discoideum... AX4] dbj|BAB12429.1| mkpA [Dictyostelium discoideum] gb|EAL63306.1| MAP kinase phosphatase [Dictyostelium discoideum AX4] XP_636822.1 9e-64 35% ...

  9. NCBI nr-aa BLAST: CBRC-DDIS-02-0214 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-02-0214 ref|XP_636822.1| MAP kinase phosphatase [Dictyostelium discoideum... AX4] dbj|BAB12429.1| mkpA [Dictyostelium discoideum] gb|EAL63306.1| MAP kinase phosphatase [Dictyostelium discoideum AX4] XP_636822.1 8e-48 29% ...

  10. NCBI nr-aa BLAST: CBRC-DDIS-05-0037 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-05-0037 ref|XP_636822.1| MAP kinase phosphatase [Dictyostelium discoideum... AX4] dbj|BAB12429.1| mkpA [Dictyostelium discoideum] gb|EAL63306.1| MAP kinase phosphatase [Dictyostelium discoideum AX4] XP_636822.1 0.0 89% ...

  11. NCBI nr-aa BLAST: CBRC-DDIS-04-0054 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-04-0054 ref|XP_636822.1| MAP kinase phosphatase [Dictyostelium discoideum... AX4] dbj|BAB12429.1| mkpA [Dictyostelium discoideum] gb|EAL63306.1| MAP kinase phosphatase [Dictyostelium discoideum AX4] XP_636822.1 6e-46 31% ...

  12. Dicty_cDB: VHG483 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 0.0 1 ( BJ442780 ) Dictyostelium discoideum cDNA clone:ddv50o20, 3' ... 1247 0.0 1 ( BJ442687 ) Dictyosteliu...m discoideum cDNA clone:ddv50m18, 3' ... 1247 0.0 1 ( BJ442548 ) Dictyostelium discoideum cDNA clone:ddv50a1

  13. Dicty_cDB: VHO666 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 465 0.0 1 ( BJ442773 ) Dictyostelium discoideum cDNA clone:ddv50m24, 3' ... 1465 0.0 1 ( BJ442764 ) Dictyost...elium discoideum cDNA clone:ddv50l21, 3' ... 1465 0.0 1 ( BJ442731 ) Dictyostelium discoideum cDNA clone:ddv50

  14. Dicty_cDB: VHJ763 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 76 ) Dictyostelium discoideum cDNA clone:ddv50n15, 5' ... 1160 0.0 1 ( BJ442706 ) Dictyostelium discoideum cDNA clone:ddv50...a22, 3' ... 686 0.0 3 ( BJ442690 ) Dictyostelium discoideum cDNA clone:ddv50n15, 3' ... 686 0

  15. Dicty_cDB: VHJ622 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Sequences producing significant alignments: (bits) Value N ( BJ442522 ) Dictyostelium discoideum cDNA clone:ddv50...764 ) Dictyostelium discoideum cDNA clone:ddv50l21, 3' ... 1465 0.0 1 ( BJ442731 ) Dictyostelium discoideum cDNA clone:ddv50

  16. Dicty_cDB: VHJ680 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Dictyostelium discoideum cDNA clone:ddv50o20, 3' ... 1443 0.0 1 ( BJ442687 ) Dict...yostelium discoideum cDNA clone:ddv50m18, 3' ... 1443 0.0 1 ( BJ442548 ) Dictyostelium discoideum cDNA clone:ddv50

  17. Dicty_cDB: VFN866 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 0 2 ( BJ423858 ) Dictyostelium discoideum cDNA clone:ddv50k13, 5' ... 430 0.0 2 ( BJ435821 ) Dictyostelium d...iscoideum cDNA clone:ddv28d18, 3' ... 402 e-108 1 ( BJ442673 ) Dictyostelium discoideum cDNA clone:ddv50k13,

  18. Dicty_cDB: VHJ695 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 5, 3' ... 1473 0.0 1 ( BJ442773 ) Dictyostelium discoideum cDNA clone:ddv50m24, 3' ... 1473 0.0 1 ( BJ442764... ) Dictyostelium discoideum cDNA clone:ddv50l21, 3' ... 1473 0.0 1 ( BJ442731 ) Dictyostelium discoideum cDNA clone:ddv50

  19. Dicty_cDB: VHO781 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Dictyostelium discoideum cDNA clone:ddv50m24, 3' ... 1465 0.0 1 ( BJ442764 ) Dictyostelium discoideum cDNA clone:ddv50...l21, 3' ... 1465 0.0 1 ( BJ442731 ) Dictyostelium discoideum cDNA clone:ddv50

  20. Dicty_cDB: VHH687 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 42780 ) Dictyostelium discoideum cDNA clone:ddv50o20, 3' ... 1443 0.0 1 ( BJ44268...7 ) Dictyostelium discoideum cDNA clone:ddv50m18, 3' ... 1443 0.0 1 ( BJ442548 ) Dictyostelium discoideum cDNA clone:ddv50

  1. Dicty_cDB: VHF217 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Dictyostelium discoideum cDNA clone:ddv50j21, 5' ... 100 3e-17 1 ( BJ423810 ) Di...ctyostelium discoideum cDNA clone:ddv50a16, 5' ... 100 3e-17 1 ( BJ423633 ) Dictyostelium discoideum cDNA cl

  2. Dicty_cDB: VHJ756 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available s producing significant alignments: (bits) Value N ( BJ423885 ) Dictyostelium discoideum cDNA clone:ddv50p13...) Dictyostelium discoideum cDNA clone:ddv34h10, 5' ... 674 0.0 2 ( BJ423936 ) Dictyostelium discoideum cDNA clone:ddv50

  3. Dicty_cDB: VHP461 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 1 ( BJ442773 ) Dictyostelium discoideum cDNA clone:ddv50m24, 3' ... 1465 0.0 1 ( BJ442764 ) Dictyostelium d...iscoideum cDNA clone:ddv50l21, 3' ... 1465 0.0 1 ( BJ442731 ) Dictyostelium discoideum cDNA clone:ddv50e24,

  4. Dicty_cDB: VHJ660 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available nificant alignments: (bits) Value N ( BJ442657 ) Dictyostelium discoideum cDNA clone:ddv50...( BJ423840 ) Dictyostelium discoideum cDNA clone:ddv50g16, 5' ... 127 8e-37 2 ( BJ423768 ) Dictyostelium discoideum cDNA clone:ddv50

  5. Dicty_cDB: AFM205 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available electin gene, complet... 1074 0.0 1 ( AC115684 ) Dictyostelium discoideum chromosom...(bits) Value N ( BJ346803 ) Dictyostelium discoideum cDNA clone:dda25i02, 3' ... 1090 0.0 1 ( AY392439 ) Dictyostelium discoideum P-s

  6. NCBI nr-aa BLAST: CBRC-DDIS-01-0132 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-01-0132 ref|XP_646256.1| cellulose synthase [Dictyostelium discoideum AX4...] gb|AAF00200.1|AF163835_1 cellulose synthase [Dictyostelium discoideum] gb|EAL71912.1| cellulose synthase [Dictyostelium discoideum AX4] XP_646256.1 0.0 99% ...

  7. Comparison of the Dictyostelium rasD and ecmA genes reveals two distinct mechanisms whereby an mRNA may become enriched in prestalk cells.

    Science.gov (United States)

    Jermyn, K; Wiliams, J

    1995-04-01

    The Dictyostelium ras gene, rasD, encodes an mRNA that is more abundant in prestalk than prespore cells in the migratory slug. Its expression is inducible by extracellular cAMP but is not inducible by the prestalk and stalk cell morphogen differentiation inducing factor (DIF). We show that a rasD-lacZ fusion gene is first expressed in approximately one half of the cells in the aggregate, including some cells that also express a prespore-specific marker. The amount of rasD-lacZ fusion protein in prespore cells then diminishes as the slug is formed. Analysis of a rasD-lacZ fusion protein with an N terminal substitution that reduces protein stability within the cell provides strong confirmatory evidence that the ras gene product becomes enriched in prestalk cells by selective repression of gene expression in prespore cells. In contrast, the DIF-inducible ecmA gene is expressed only in those cells that will become prestalk cells in the migratory slug. These results show that there are two different ways in which an mRNA may become enriched in prestalk cells and support the view that DIF is the inducer of prestalk cell differentiation.

  8. Germination of Dictyotelium discoideum spores. A sup 31 P NMR analysis

    Energy Technology Data Exchange (ETDEWEB)

    Klein, G.; Martin, J.B.; Bof, M.; Satre, M. (Centre d' Etudes Nucleaires, Grenoble (France)); Cotter, D.A. (Univ. of Windsor, Ontario (Canada))

    1988-10-18

    Perchloric acid extracts of Dictyostelium spores have been investigated by {sup 31}P nuclear magnetic resonance (NMR) spectroscopy. This analysis has allowed the assignment of all the {sup 31}P resonances observed in vivo to specific compounds. Dormant spores have been found to contain as prominent phosphorylated metabolites two phosphomonoesters, phosphoethanolamine and inositol hexakis(phosphate), two phosphodiesters, glycerophosphocholine and glycerophosphoethanolamine, as well as nucleoside triphosphates and polyphosphates. The very large amounts of glycerophosphocholine, glycerophosphoethanolamine, and phosphoethanolamine in spores were the most remarkable differences from Dictyostelium amoebae. In vivo {sup 31}P NMR has shown that the peak of nucleoside triphosphates in dormant spores was maintained metabolically since it disappeared completely upon anaerobiosis. The pH-sensitive {sup 31}P NMR signal of phosphoethanolamine was used to determine internal pH, and a value of pH 6.5 was found in aerobic Dictyostelium dormant spores. Spore germination, induced by activation with heat shock treatment, was monitored noninvasively by {sup 31}P NMR. No change in phosphorylated components was observed to have occurred during the activation step. The major modifications in phosphorylated metabolites observed upon germination of the activated spores were the progressive disappearance of the two phosphodiesters glycerophosphocholine and glycerophosphoethanolamine.

  9. c-di-GMP induction of Dictyostelium cell death requires the polyketide DIF-1.

    Science.gov (United States)

    Song, Yu; Luciani, Marie-Françoise; Giusti, Corinne; Golstein, Pierre

    2015-02-15

    Cell death in the model organism Dictyostelium, as studied in monolayers in vitro, can be induced by the polyketide DIF-1 or by the cyclical dinucleotide c-di-GMP. c-di-GMP, a universal bacterial second messenger, can trigger innate immunity in bacterially infected animal cells and is involved in developmental cell death in Dictyostelium. We show here that c-di-GMP was not sufficient to induce cell death in Dictyostelium cell monolayers. Unexpectedly, it also required the DIF-1 polyketide. The latter could be exogenous, as revealed by a telling synergy between c-di-GMP and DIF-1. The required DIF-1 polyketide could also be endogenous, as shown by the inability of c-di-GMP to induce cell death in Dictyostelium HMX44A cells and DH1 cells upon pharmacological or genetic inhibition of DIF-1 biosynthesis. In these cases, c-di-GMP-induced cell death was rescued by complementation with exogenous DIF-1. Taken together, these results demonstrated that c-di-GMP could trigger cell death in Dictyostelium only in the presence of the DIF-1 polyketide or its metabolites. This identified another element of control to this cell death and perhaps also to c-di-GMP effects in other situations and organisms.

  10. Isolation of furocoumarins from bergamot fruits as HL-60 differentiation-inducing compounds.

    Science.gov (United States)

    Kawaii, S; Tomono, Y; Katase, E; Ogawa, K; Yano, M

    1999-10-01

    The HL-60 differentiation-inducing compounds in bergamot fruits were isolated with column chromatography and identified as bergamottin, bergapten, and citropten by (1)H and (13)C NMR. Their HL-60 differentiation-inducing activity was measured by examining nitro blue tetrazolium (NBT) reducing, nonspecific acid esterase (NSE), specific esterase (SE), and phagocytic activities, and bergamottin showed the strongest activity among the coumarins isolated from bergamot fruits. The structure-activity relationship obtained from HL-60 differentiation assay suggests that hydrophobicity of furocoumarins is correlated with their activity.

  11. SodC modulates ras and PKB signaling in Dictyostelium.

    Science.gov (United States)

    Castillo, Boris; Kim, Seon-Hee; Sharief, Mujataba; Sun, Tong; Kim, Lou W

    2017-01-01

    We have previously reported that the basal RasG activity is aberrantly high in cells lacking Superoxide dismutase C (SodC). Here we report that other Ras proteins such as RasC and RasD activities are not affected in sodC(-) cells and mutagenesis studies showed that the presence of the Cys(118) in the Ras proteins is essential for the superoxide-mediated activation of Ras proteins in Dictyostelium. In addition to the loss of SodC, lack of extracellular magnesium ions increased the level of intracellular superoxide and active RasG proteins. Aberrantly active Ras proteins in sodC(-) cells persistently localized at the plasma membrane, but those in wild type cells under magnesium deficient medium exhibited intracellular vesicular localization. Interestingly, the aberrantly activated Ras proteins in wild type cells were largely insulated from their normal downstream events such as Phosphatidylinositol-3,4,5-P3 (PIP3) accumulation, Protein Kinase B (PKB) activation, and PKBs substrates phosphorylation. Intriguingly, however, aberrantly activated Ras proteins in sodC(-) cells were still engaged in signaling to their downstream targets, and thus excessive PKBs substrates phosphorylation persisted. In summary, we suggest that SodC and RasG proteins are essential part of a novel inhibitory mechanism that discourages oxidatively stressed cells from chemotaxis and thus inhibits the delivery of potentially damaged genome to the next generation.

  12. Traction force and its regulation during cytokinesis in Dictyostelium cells.

    Science.gov (United States)

    Jahan, Md Golam Sarowar; Yumura, Shigehiko

    2017-09-01

    Cytokinesis is the final stage of cell division. Dictyostelium cells have multiple modes of cytokinesis, including cytokinesis A, B and C. Cytokinesis A is a conventional mode, which depends on myosin II in the contractile ring. Myosin II null cells divide depending on substratum-attachment (cytokinesis B) or in a multi-polar fashion independent of the cell cycle (cytokinesis C). We investigated the traction stress exerted by dividing cells in the three different modes using traction force microscopy. In all cases, the traction forces were directed inward from both poles. Interestingly, the traction stress of cytokinesis A was the smallest of the three modes. Latrunculin B, an inhibitor of actin polymerization, completely diminished the traction stress of dividing cells, but blebbistatin, an inhibitor of myosin II ATPase, increased the traction stress. Myosin II is proposed to contribute to the detachment of cell body from the substratum. When the cell-substratum attachment was artificially strengthened by a poly-lysine coating, wild type cells increased their traction stress in contrast to myosin II null and other cytokinesis-deficient mutant cells, which suggests that wild type cells may increase their own power to conduct their cytokinesis. The cytokinesis-deficient mutants frequently divided unequally, whereas wild type cells divided equally. A traction stress imbalance between two daughter halves was correlated with cytokinesis failure. We discuss the regulation of cell shape changes during cell division through mechanosensing. Copyright © 2017 Elsevier GmbH. All rights reserved.

  13. Dicty_cDB: [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ents: (bits) Value N L36204 |L36204.1 Dictyostelium discoideum cysteine proteinas...e (CP4) mRNA, complete cds. 922 0.0 7 U72746 |U72746.1 Dictyostelium discoideum cysteine proteinase (cprG) m...RNA, complete cds. 145 e-145 9 L36205 |L36205.1 Dictyostelium discoideum cysteine proteinase CP5 mRNA, compl...ete cds. 121 e-139 10 AC117072 |AC117072.2 Dictyostelium discoideum chromosome 2 map 3323568-3470138 strain ...AX4, complete sequence. 121 e-119 13 U72745 |U72745.1 Dictyostelium discoideum cy

  14. Dicty_cDB: [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ant alignments: (bits) Value N AC116957 |AC116957.2 Dictyostelium discoideum chro...mosome 2 map 1685067-2090751 strain AX4, complete sequence. 967 0.0 3 X03281 |X03281.1 Dictyostelium discoid...eum gene for actin A8. 844 0.0 2 AC116986 |AC116986.2 Dictyostelium discoideum chromosome 2 map 2234041-2567...0.0 3 AC115579 |AC115579.2 Dictyostelium discoideum chromosome 2 map 4915084-5005...461 strain AX4, complete sequence. 791 0.0 4 AC115577 |AC115577.2 Dictyostelium discoideum chromosome 2 map

  15. Dicty_cDB: [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available alignments: (bits) Value N AC116956 |AC116956.2 Dictyostelium discoideum chromosome 2 map 1418423-1684967 st...rain AX4, complete sequence. 963 0.0 6 X03282 |X03282.1 dictyostelium discoideum gene for actin A12. 926 0.0... strain AX4, complete sequence. 765 0.0 7 AC116305 |AC116305.2 Dictyostelium discoideum chromosome 2 map 100...cds. 724 0.0 4 AC115577 |AC115577.2 Dictyostelium discoideum chromosome 2 map 465...7875-4914984 strain AX4, complete sequence. 724 0.0 12 AC115579 |AC115579.2 Dictyostelium discoideum chromos

  16. Dicty_cDB: VHJ514 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available E Sequences producing significant alignments: (bits) Value N ( BJ442519 ) Dictyostelium discoideum cDNA clone:ddv50...NA clone:ddv51l05, 3' ... 1338 0.0 1 ( BJ442780 ) Dictyostelium discoideum cDNA clone:ddv50o20, 3' ... 1338 ...0.0 1 ( BJ442687 ) Dictyostelium discoideum cDNA clone:ddv50m18, 3' ... 1338 0.0 1 ( BJ442548 ) Dictyosteliu...m discoideum cDNA clone:ddv50a11, 3' ... 1338 0.0 1 ( BJ441725 ) Dictyostelium discoideum cDNA clone:ddv47k1

  17. Dicty_cDB: VHJ867 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ( BJ442653 ) Dictyostelium discoideum cDNA clone:ddv50f18, 3' ... 1499 0.0 1 ( B...J442525 ) Dictyostelium discoideum cDNA clone:ddv50l04, 3' ... 1294 0.0 3 ( BJ445359 ) Dictyostelium discoid...eum cDNA clone:ddv59a09, 3' ... 1225 0.0 3 ( BJ442499 ) Dictyostelium discoideum cDNA clone:ddv50g01, 3' ......a02, 3' ... 1166 0.0 2 ( BJ423836 ) Dictyostelium discoideum cDNA clone:ddv50f18, 5' ... 1136 0.0 1 ( BJ4446

  18. Dicty_cDB: Contig-U13701-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available lium discoideum cDNA clone:ddv50m14, 3' ... 105 4e-19 1 ( BJ445395 ) Dictyostelium discoideum cDNA clone:ddv...86 ) Dictyostelium discoideum cDNA clone:ddv51e17, 3' ... 92 6e-15 1 ( BJ442677 ) Dictyostelium discoideum cDNA clone:ddv50...' ... 80 2e-11 1 ( BJ442683 ) Dictyostelium discoideum cDNA clone:ddv50m13, 3' .....ctyostelium discoideum cDNA clone:ddv50m14, 3' end, single read. Length = 140 Score = 105 bits (53), Expect

  19. Ras proteins have multiple functions in vegetative cells of Dictyostelium.

    Science.gov (United States)

    Bolourani, Parvin; Spiegelman, George; Weeks, Gerald

    2010-11-01

    During the aggregation of Dictyostelium cells, signaling through RasG is more important in regulating cyclic AMP (cAMP) chemotaxis, whereas signaling through RasC is more important in regulating the cAMP relay. However, RasC is capable of substituting for RasG for chemotaxis, since rasG⁻ cells are only partially deficient in chemotaxis, whereas rasC⁻/rasG⁻ cells are totally incapable of chemotaxis. In this study we have examined the possible functional overlap between RasG and RasC in vegetative cells by comparing the vegetative cell properties of rasG⁻, rasC⁻, and rasC⁻/rasG⁻ cells. In addition, since RasD, a protein not normally found in vegetative cells, is expressed in vegetative rasG⁻ and rasC⁻/rasG⁻ cells and appears to partially compensate for the absence of RasG, we have also examined the possible functional overlap between RasG and RasD by comparing the properties of rasG⁻ and rasC⁻/rasG⁻ cells with those of the mutant cells expressing higher levels of RasD. The results of these two lines of investigation show that RasD is capable of totally substituting for RasG for cytokinesis and growth in suspension, whereas RasC is without effect. In contrast, for chemotaxis to folate, RasC is capable of partially substituting for RasG, but RasD is totally without effect. Finally, neither RasC nor RasD is able to substitute for the role that RasG plays in regulating actin distribution and random motility. These specificity studies therefore delineate three distinct and none-overlapping functions for RasG in vegetative cells.

  20. The Cyclic Nucleotide Specificity of Three cAMP Receptors in Dictyostelium

    NARCIS (Netherlands)

    Johnson, Ronald L.; Haastert, Peter J.M. van; Kimmel, Alan R.; Saxe III, Charles L.; Jastorff, Bernd; Devreotes, Peter N.

    1992-01-01

    cAMP receptors mediate signal transduction pathways during development in Dictyostelium. A cAMP receptor (cAR1) has been cloned and sequenced (Klein, P., Sun, T. J., Saxe, C. L., Kimmel, A. R., Johnson, R. L., and Devreotes, P. N. (1988) Science 241, 1467-1472) and recently several other cAR genes h

  1. A novel Myb homolog initiates Dictyostelium development by induction of adenylyl cyclase expression

    NARCIS (Netherlands)

    Otsuka, Hideshi; Haastert, Peter J.M. van

    1998-01-01

    Dictyostelium development is induced by starvation. The adenylyl cyclase gene ACA is one of the first genes expressed upon starvation. ACA produces extracellular cAMP that induces chemotaxis, aggregation, and differentiation in neighboring cells. Using insertional mutagenesis we have isolated a muta

  2. Sensitization of Dictyostelium chemotaxis by phosphoinositide-3-kinase-mediated self-organizing signalling patches

    NARCIS (Netherlands)

    Postma, M.; Roelofs, J.; Goedhart, J.; Loovers, H.M.; Visser, A.J.W.G.; Haastert, van P.J.M.

    2004-01-01

    The leading edge of Dictyostelium cells in chemoattractant gradients can be visualized using green fluorescent protein (GFP) tagged to the pleckstrin-homology (PH) domain of cytosolic regulator of adenylyl cyclase (CRAC), which presumable binds phosphatidylinositol-(3,4,5)triphosphate [PtdIns(3,4,5)

  3. Sensitization of Dictyostelium chemotaxis by phosphoinositide-3-kinase-mediated self-organizing signalling patches.

    NARCIS (Netherlands)

    Postma, M.; Roelofs, J.; Goedhart, J.; Loovers, H.M.; Visser, A.J.; van Haastert, P.J.

    2004-01-01

    The leading edge of Dictyostelium cells in chemoattractant gradients can be visualized using green fluorescent protein (GFP) tagged to the pleckstrin-homology (PH) domain of cytosolic regulator of adenylyl cyclase (CRAC), which presumable binds phosphatidylinositol-(3,4,5)triphosphate [PtdIns(3,4,5)

  4. PP2A/B56 and GSK3/Ras suppress PKB activity during Dictyostelium chemotaxis.

    Science.gov (United States)

    Rodriguez Pino, Marbelys; Castillo, Boris; Kim, Bohye; Kim, Lou W

    2015-12-01

    We have previously shown that the Dictyostelium protein phosphatase 2A regulatory subunit B56, encoded by psrA, modulates Dictyostelium cell differentiation through negatively affecting glycogen synthase kinase 3 (GSK3) function. Our follow-up research uncovered that B56 preferentially associated with GDP forms of RasC and RasD, but not with RasG in vitro, and psrA(-) cells displayed inefficient activation of multiple Ras species, decreased random motility, and inefficient chemotaxis toward cAMP and folic acid gradient. Surprisingly, psrA(-) cells displayed aberrantly high basal and poststimulus phosphorylation of Dictyostelium protein kinase B (PKB) kinase family member PKBR1 and PKB substrates. Expression of constitutively active Ras mutants or inhibition of GSK3 in psrA(-) cells increased activities of both PKBR1 and PKBA, but only the PKBR1 activity was increased in wild-type cells under the equivalent conditions, indicating that either B56- or GSK3-mediated suppressive mechanism is sufficient to maintain low PKBA activity, but both mechanisms are necessary for suppressing PKBR1. Finally, cells lacking RasD or RasC displayed normal PKBR1 regulation under GSK3-inhibiting conditions, indicating that RasC or RasD proteins are essential for GSK3-mediated PKBR1 inhibition. In summary, B56 constitutes inhibitory circuits for PKBA and PKBR1 and thus heavily affects Dictyostelium chemotaxis.

  5. Characterization of a 1,4-{beta}-D-glucan synthase from Dictyostelium. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Blanton, R.L.

    1996-02-01

    The study of cellulose biosynthesis has a long history of frustrations, false leads, and setbacks. The authors have been able to proceed further than others who have studied eukaryotic cellulose synthesis because of the high level of enzyme activity in crude membrane preparations from developing Dictyostelium cells. This has made possible experiments to study factors that influence the activity, to determine cellular localization, and to study the development regulation of the enzyme activity. In higher plants, the challenge is still to obtain highly active membrane preparations. However, they have not been able to move beyond the level of crude membranes. The high starting activity of Dictyostelium membranes gave hope that cellulose synthase activity could be purified, allowing the identification of the polypeptides involved in cellulose synthesis. The first step in the purification of a membrane-associated activity is the solubilization of the activity; this they have not yet been able to do. They have applied some of their methods developed in the study of the Dictyostelium glucan synthase to preparation of plant membranes to see if they can obtain any in vitro activity. For instance, the disruption medium, disruption methods, and assay conditions used in Dictyostelium were used to prepare plant membranes, but without obtaining significant levels of enzyme activity.

  6. Identification and characterization of DdPDE3, a cGMP-selective phosphodiesterase from Dictyostelium

    NARCIS (Netherlands)

    Kuwayama, H; Snippe, H; Derks, M; Roelofs, J; van Haastert, PJM

    2001-01-01

    In Dictyostelium cAMP and cGMP have important functions as first and second messengers in chemotaxis and development. Two cyclic-nucleotide phosphodiesterases (DdPDE 1 and 2) have been identified previously, an extracellular dual-specificity enzyme and an intracellular cAMP-specific enzyme (encoded

  7. cAMP pulses coordinate morphogenetic movement during fruiting body formation of Dictyostelium minutum

    NARCIS (Netherlands)

    Schaap, Pauline; Konijn, Theo M.; Haastert, Peter J.M. van

    1984-01-01

    Aggregation in the primitive cellular slime mold Dictyostelium minutum proceeds by means of chemotaxis toward a continuously secreted folic acid analog. The onset of culmination is marked by the appearance of concentric waves of cell movement on the aggregate surface. Culmination proceeds by the

  8. The G Protein β Subunit Is Essential for Multiple Responses to Chemoattractants in Dictyostelium

    NARCIS (Netherlands)

    Wu, Lijun; Valkema, Romi; Haastert, Peter J.M. van; Devreotes, Peter N.

    1995-01-01

    Increasing evidence suggests that the beta gamma-subunit dimers of heterotrimeric G proteins play a pivotal role in transducing extracellular signals. The recent construction of G beta null mutants (g beta(-)) in Dictyostelium provides a unique opportunity to study the role of beta gamma dimers in s

  9. GxcC connects Rap and Rac signaling during Dictyostelium development

    NARCIS (Netherlands)

    Plak, Katarzyna; Veltman, Douwe; Fusetti, Fabrizia; Beeksma, Jetze; Rivero, Francisco; Van Haastert, Peter J. M.; Kortholt, Arjan

    2013-01-01

    Background: Rap proteins belong to the Ras family of small G-proteins. Dictyostelium RapA is essential and implicated in processes throughout the life cycle. In early development and chemotaxis competent cells RapA induces pseudopod formation by activating PI3K and it regulates substrate attachment

  10. A novel Myb homolog initiates Dictyostelium development by induction of adenylyl cyclase expression

    NARCIS (Netherlands)

    Otsuka, Hideshi; Haastert, Peter J.M. van

    1998-01-01

    Dictyostelium development is induced by starvation. The adenylyl cyclase gene ACA is one of the first genes expressed upon starvation. ACA produces extracellular cAMP that induces chemotaxis, aggregation, and differentiation in neighboring cells. Using insertional mutagenesis we have isolated a muta

  11. Dicty_cDB: VHO672 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ictyostelium discoideum cDNA clone:ddv51k15, 3' ... 1465 0.0 1 ( BJ442773 ) Dictyostelium discoideum cDNA clone:ddv50...m24, 3' ... 1465 0.0 1 ( BJ442764 ) Dictyostelium discoideum cDNA clone:ddv50l21, 3' ... 1465 0.0 1... ( BJ442731 ) Dictyostelium discoideum cDNA clone:ddv50e24, 3' ... 1465 0.0 1 ( B

  12. Dicty_cDB: VHP414 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ostelium discoideum cDNA clone:ddv50g15, 3' ... 1635 0.0 3 ( BJ437910 ) Dictyostelium discoideum cDNA clone:...J442583 ) Dictyostelium discoideum cDNA clone:ddv50g12, 3' ... 1614 0.0 2 ( BJ430...cDNA clone:ddv38n15, 3' ... 1608 0.0 3 ( BJ442531 ) Dictyostelium discoideum cDNA clone:ddv50m05, 3' ... 159

  13. Dicty_cDB: VHP357 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ctyostelium discoideum cDNA clone:ddv51k15, 3' ... 1467 0.0 1 ( BJ442773 ) Dictyostelium discoideum cDNA clone:ddv50...m24, 3' ... 1467 0.0 1 ( BJ442764 ) Dictyostelium discoideum cDNA clone:ddv50...l21, 3' ... 1467 0.0 1 ( BJ442731 ) Dictyostelium discoideum cDNA clone:ddv50e24, 3' ... 1467 0.0 1 ( BJ

  14. Dictyostelium RasD is required for normal phototaxis, but not differentiation.

    Science.gov (United States)

    Wilkins, A; Khosla, M; Fraser, D J; Spiegelman, G B; Fisher, P R; Weeks, G; Insall, R H

    2000-06-01

    RasD, a Dictyostelium homolog of mammalian Ras, is maximally expressed during the multicellular stage of development. Normal Dictyostelium aggregates are phototactic and thermotactic, moving towards sources of light and heat with great sensitivity. We show that disruption of the gene for rasD causes a near-total loss of phototaxis and thermotaxis in mutant aggregates, without obvious effects on undirected movement. Previous experiments had suggested important roles for RasD in development and cell-type determination. Surprisingly, rasD(-) cells show no obvious changes in these processes. These cells represent a novel class of phototaxis mutant, and indicate a role for a Ras pathway in the connections between stimuli and coordinated cell movement.

  15. A measure of endosomal pH by flow cytometry in Dictyostelium

    Directory of Open Access Journals (Sweden)

    Cosson Pierre

    2009-01-01

    Full Text Available Abstract Background Dictyostelium amoebae are frequently used to study the organization and function of the endocytic pathway, and specific protocols are essential to measure the dynamics of endocytic compartments and their internal pH. Findings We have revisited these classical protocols to measure more accurately endosomal pH, making use of a fluorescent probe (Oregon green more adequate for very acidic pH values. This pH-sensitive probe was combined with a pH-insensitive marker, in order to visualize simultaneously endosome dynamics and pH changes. Finally, a flow cytometer was used to measure endosomal pH in individual cells. Conclusion Using these simple protocols the endosomal pH of endocytic compartments can be assessed accurately, revealing the extreme acidity of Dictyostelium lysosomes (pH

  16. Dicty_cDB: [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available alignments: (bits) Value N ( U61990 ) Dictyostelium discoideum ThyB (thyB) mRNA, complete... 954 0.0 2 ( AF510846 ) Dictyostelium di...scoideum calmodulin-binding prote... 954 0.0 2 ( AU062155 ) Dictyostelium di...scoideum slug cDNA, clone SLH838. 841 0.0 3 ( BJ432335 ) Dictyostelium discoideum cDNA cl...one:ddv18l07, 3' ... 969 0.0 1 ( AY192984 ) Dictyostelium discoideum thymidine kinase 1 (TK1)... 954 0.0 1 ( AU270331 ) Di...ctyostelium discoideum vegetative cDNA clone:VS... 954 0.0 1 ( BJ446521 ) Dictyostelium di

  17. Dicty_cDB: [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available . 4 Homology vs DNA Score E Sequences producing significant alignments: (bits) Value N X03281 |X03281.1 Dictyostelium di...scoideum gene for actin A8. 1895 0.0 3 AC116957 |AC116957.2 Dictyostelium discoideum chromosome ...scoideum actin 15 gene, complete cds. 1752 0.0 3 AC115579 |AC115579.2 Dictyostelium discoideum chromosom...e 2 map 4915084-5005461 strain AX4, complete sequence. 1752 0.0 3 AC116986 |AC116986.2 Dictyostelium discoid...1443 0.0 14 AC116956 |AC116956.2 Dictyostelium discoideum chromosome 2 map 1418423-1684967 strain AX4, compl

  18. Dicty_cDB: [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available lue N AC116922 |AC116922.1 Dictyostelium discoideum chromosome 2 map 4969700-4990...227 strain AX4, *** SEQUENCING IN PROGRESS ***. 920 0.0 10 AC115608 |AC115608.2 Dictyostelium discoideum chr...omosome 2 map 6061442-6097630 strain AX4, complete sequence. 920 0.0 10 AC115681 |AC115681.2 Dictyostelium di... 14 AC115683 |AC115683.2 Dictyostelium discoideum chromosome 2 map complement(6135149-6105997) strain AX4, c...omplete sequence. 291 0.0 13 AC116985 |AC116985.2 Dictyostelium discoideum chromosome 2 map 6135249-6143598

  19. Dicty_cDB: [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ogy vs DNA Score E Sequences producing significant alignments: (bits) Value N AC116984 |AC116984.2 Dictyostelium di...RNA, complete cds. 167 e-100 8 AC117076 |AC117076.2 Dictyostelium discoideum chromosome 2 map 5862124-604577...2 strain AX4, complete sequence. 167 1e-82 11 X00601 |X00601.1 Dictyostelium disc...oideum ribosomal RNA gene. 311 1e-80 1 AY171066 |AY171066.1 Dictyostelium discoideum extrachromosomal palind...romic ribosomal RNA gene sequence, central segment. 311 1e-80 1 V00192 |V00192.1 Dictyostelium discoideum 5.

  20. Dicty_cDB: VHJ671 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Dictyostelium discoideum cDNA clone:ddv52o18, 3' ... 1457 0.0 1 ( BJ442687 ) Dictyostelium discoideum cDNA clone:ddv50...e:ddv47k18, 3' ... 1457 0.0 1 ( BJ442596 ) Dictyostelium discoideum cDNA clone:ddv50k07, 3' ... 1451 0.0 1 (... BJ442548 ) Dictyostelium discoideum cDNA clone:ddv50a11, 3' ... 1451 0.0 1 ( BJ438342 ) Dictyostelium disco

  1. GxcC connects Rap and Rac signaling during Dictyostelium development.

    Science.gov (United States)

    Plak, Katarzyna; Veltman, Douwe; Fusetti, Fabrizia; Beeksma, Jetze; Rivero, Francisco; Van Haastert, Peter J M; Kortholt, Arjan

    2013-01-30

    Rap proteins belong to the Ras family of small G-proteins. Dictyostelium RapA is essential and implicated in processes throughout the life cycle. In early development and chemotaxis competent cells RapA induces pseudopod formation by activating PI3K and it regulates substrate attachment and myosin disassembly via the serine/threonine kinase Phg2. RapA is also important in late development, however so far little is known about the downstream effectors of RapA that play a role in this process. Here we show that cells expressing constitutively active RapA exhibit a high level of Rac activation. With a pull-down screen coupled to mass spectrometry, we identified the Rac specific guanine nucleotide exchange factor, GxcC, as Rap binding partner. GxcC binds directly and specifically to active RapA and binds to a subset of Dictyostelium Rac proteins. Deletion studies revealed that this pathway is involved in regulating Dictyostelium development. GxcC provides a novel link between Rap and Rac signalling and is one of the Rap effectors regulating the progression of multicellular development.

  2. Dicty_cDB: VFO694 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available yostelium discoideum cDNA clone:ddv62o12, 3' ... 1255 0.0 1 ( U48706 ) Dictyostelium discoideum small aggr...egate formation ... 1189 0.0 4 ( BJ436350 ) Dictyostelium discoideum cDNA clone:ddv

  3. Dicty_cDB: VSI331 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ictyostelium discoideum cDNA clone:ddv50k10, 5' ... 688 0.0 3 ( AU265613 ) Dictyostelium discoideum vegetati...ve cDNA clone:VS... 716 0.0 3 ( BJ442597 ) Dictyostelium discoideum cDNA clone:ddv50k10, 3' ... 634 0.0 4 (

  4. Dicty_cDB: VHF536 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ium discoideum cDNA clone:ddv51j06, 3' ... 1237 0.0 1 ( BJ442633 ) Dictyostelium discoideum cDNA clone:ddv50...b17, 3' ... 1237 0.0 1 ( BJ442555 ) Dictyostelium discoideum cDNA clone:ddv50b12, 3' ... 1237 0.0 1 ( BJ4416

  5. Dicty_cDB: VHP556 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available discoideum cDNA clone:ddv51l13, 5' ... 133 2e-27 1 ( BJ423702 ) Dictyostelium discoideum cDNA clone:ddv50j0...3, 5' ... 133 2e-27 1 ( BJ423663 ) Dictyostelium discoideum cDNA clone:ddv50a04, 5' ... 133 2e-27 1 ( BJ4235

  6. Dicty_cDB: Contig-U14834-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ostelium discoideum chromosome 2 map 3879572... 127 8e-26 1 ( BJ442734 ) Dictyostelium discoideum cDNA clone:ddv50...f22, 3' ... 127 8e-26 1 ( BJ423915 ) Dictyostelium discoideum cDNA clone:ddv50f22, 5' ... 98 7e-17 1 (

  7. Dicty_cDB: VHM389 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available stelium discoideum cDNA clone:ddv50o18, 3' ... 1138 0.0 1 ( BJ441974 ) Dictyostelium discoideum cDNA clone:d...lone:ddv48n08, 5' ... 42 2e-11 3 ( BJ423884 ) Dictyostelium discoideum cDNA clone:ddv50o18, 5' ... 42 2e-11

  8. Dicty_cDB: VHJ801 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available telium discoideum cDNA clone:ddv50b02, 3' ... 888 0.0 1 ( BJ437026 ) Dictyosteliu... ) Dictyostelium discoideum cDNA clone:ddv50n22, 3' ... 567 e-157 1 ( BJ446199 ) Dictyostelium discoideum cD

  9. Dicty_cDB: VHF690 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ium discoideum cDNA clone:ddv52a15, 3' ... 622 e-174 1 ( BJ442547 ) Dictyostelium discoideum cDNA clone:ddv50...a10, 3' ... 622 e-174 1 ( BJ442480 ) Dictyostelium discoideum cDNA clone:ddv50b06, 3' ... 622 e-174 1 ( BJ4

  10. Dicty_cDB: VHI831 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available discoideum cDNA clone:ddv25i24, 3' ... 1370 0.0 1 ( BJ442698 ) Dictyostelium discoideum cDNA clone:ddv50o18...e:ddv48n08, 5' ... 101 1e-22 2 ( BJ423884 ) Dictyostelium discoideum cDNA clone:ddv50o18, 5' ... 88 1e-18 2

  11. Dicty_cDB: VHJ605 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ts: (bits) Value N ( BJ423697 ) Dictyostelium discoideum cDNA clone:ddv50i02, 5' ...elium discoideum slug cDNA, clone SSD494. 438 e-120 2 ( BJ442509 ) Dictyostelium discoideum cDNA clone:ddv50

  12. Dicty_cDB: VHN330 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available discoideum cDNA clone:ddv50n17, 3' ... 1122 0.0 1 ( BJ442634 ) Dictyostelium discoideum cDNA clone:ddv50...b18, 3' ... 1122 0.0 1 ( BJ442595 ) Dictyostelium discoideum cDNA clone:ddv50j10, 3'

  13. Dicty_cDB: Contig-U16317-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available BJ325910 ) Dictyostelium discoideum cDNA clone:dda2o23, 5' e... 531 0.0 6 ( BJ325...( BJ340600 ) Dictyostelium discoideum cDNA clone:dda2o23, 3' e... 476 0.0 4 ( BJ327722 ) Dictyostelium disco

  14. Dicty_cDB: Contig-U13827-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available m05, 3' ... 1261 0.0 1 ( BJ340598 ) Dictyostelium discoideum cDNA clone:dda2o21, 3' e... 1261 0.0 1 ( BJ4310... 3 ( BJ325909 ) Dictyostelium discoideum cDNA clone:dda2o21, 5' e... 1043 0.0 1 ( BJ361743 ) Dictyostelium d

  15. Dicty_cDB: VHN855 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available clone:ddv51k15, 3' ... 1409 0.0 1 ( BJ442773 ) Dictyostelium discoideum cDNA clone:ddv50m24, 3' ... 1409 0.0... 1 ( BJ442764 ) Dictyostelium discoideum cDNA clone:ddv50l21, 3' ... 1409 0.0 1 ( BJ442731 ) Dictyostelium d

  16. Dicty_cDB: VHJ571 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available equences producing significant alignments: (bits) Value N ( BJ423872 ) Dictyostelium discoideum cDNA clone:ddv50...2686 ) Dictyostelium discoideum cDNA clone:ddv50m17, 3' ... 280 5e-71 1 ( BJ442120 ) Dictyostelium discoideu

  17. Dicty_cDB: VSI120 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 0.0 2 ( BJ423789 ) Dictyostelium discoideum cDNA clone:ddv50m11, 5' ... 973 0.0 2 ( C23686 ) Dictyostelium d... 973 0.0 2 ( BJ442607 ) Dictyostelium discoideum cDNA clone:ddv50m11, 3' ... 973 0.0 2 ( AU265127 ) Dictyost

  18. Dicty_cDB: VHJ648 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ts: (bits) Value N ( BJ442618 ) Dictyostelium discoideum cDNA clone:ddv50o12, 3' ... 1289 0.0 1 ( AC116925 )...42702 ) Dictyostelium discoideum cDNA clone:ddv50p18, 3' ... 1263 0.0 1 ( BJ441854 ) Dictyostelium discoideu

  19. Dicty_cDB: SLA853 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 1 ( BJ442525 ) Dictyostelium discoideum cDNA clone:ddv50l04, 3' ... 710 0.0 1 ( C25574 ) Dictyostelium disco...ium discoideum cDNA clone:ddv50g01, 3' ... 668 0.0 2 ( BJ438430 ) Dictyostelium d

  20. Dicty_cDB: SFF823 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available gy vs DNA Score E Sequences producing significant alignments: (bits) Value N AF305060 |AF305060.1 Dictyostelium discoideum Wiscott...id:none) Dictyostelium discoideum Wiscott-A... 83 3e-15 AC117076_18( AC117076 |pid:none) Dictyostelium disco

  1. Differentiation-inducing and anti-proliferative activities of lupeol on canine melanoma cells.

    Science.gov (United States)

    Ogihara, Kikumi; Naya, Yuko; Okamoto, Yoshiharu; Hata, Keishi

    2014-01-01

    Canine melanoma is the most common oral malignant tumor reported in the field of veterinary medicine. We found that lupeol, a lupine triterpene, inhibited mouse melanoma cell growth in vitro and in vivo by inducing cell differentiation. In the present study, we examined the differentiation-inducing activities of lupeol on 4 canine melanoma cells in vitro and in vivo. The induction of canine melanoma cell differentiation by lupeol was confirmed by evaluating some differentiation markers such as tyrosinase with real-time RT-PCR. Furthermore, we transplanted canine melanoma cells into a severe combined immunodeficiency mouse, and studied the anti-progressive effects of lupeol on tumor tissue. The gene expression of microphthalmia-associated transcription factor, tyrosinase, and tyrosinase-related protein-2, which are markers of pigment cell differentiation, was induced in 4 canine oral malignant melanoma cells by lupeol, and the agent markedly inhibited tumor progression in canine melanoma-bearing mice.

  2. Dicty_cDB: Contig-U16169-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Sequences producing significant alignments: (bits) Value N ( C22770 ) Dictyosteliu...m discoideum gamete cDNA, clone FCL-AB23. 1703 0.0 1 ( BJ410380 ) Dictyostelium discoideum cDNA clone:ddv1...2f12, 5' ... 1231 0.0 1 ( BJ410550 ) Dictyostelium discoideum cDNA clone:ddv12p22, 5' ... 1221 0.0 1 ( BJ415926 ) Dictyosteliu...m discoideum cDNA clone:ddv24o02, 5' ... 1219 0.0 1 ( BJ410329 ) Dictyosteliu...m discoideum cDNA clone:ddv12i06, 5' ... 1203 0.0 1 ( BJ410184 ) Dictyostelium discoideum cDNA

  3. Myosin-II-Mediated Directional Migration of Dictyostelium Cells in Response to Cyclic Stretching of Substratum

    Science.gov (United States)

    Iwadate, Yoshiaki; Okimura, Chika; Sato, Katsuya; Nakashima, Yuta; Tsujioka, Masatsune; Minami, Kazuyuki

    2013-01-01

    Living cells are constantly subjected to various mechanical stimulations, such as shear flow, osmotic pressure, and hardness of substratum. They must sense the mechanical aspects of their environment and respond appropriately for proper cell function. Cells adhering to substrata must receive and respond to mechanical stimuli from the substrata to decide their shape and/or migrating direction. In response to cyclic stretching of the elastic substratum, intracellular stress fibers in fibroblasts and endothelial, osteosarcoma, and smooth muscle cells are rearranged perpendicular to the stretching direction, and the shape of those cells becomes extended in this new direction. In the case of migrating Dictyostelium cells, cyclic stretching regulates the direction of migration, and not the shape, of the cell. The cells migrate in a direction perpendicular to that of the stretching. However, the molecular mechanisms that induce the directional migration remain unknown. Here, using a microstretching device, we recorded green fluorescent protein (GFP)-myosin-II dynamics in Dictyostelium cells on an elastic substratum under cyclic stretching. Repeated stretching induced myosin II localization equally on both stretching sides in the cells. Although myosin-II-null cells migrated randomly, myosin-II-null cells expressing a variant of myosin II that cannot hydrolyze ATP migrated perpendicular to the stretching. These results indicate that Dictyostelium cells accumulate myosin II at the portion of the cell where a large strain is received and migrate in a direction other than that of the portion where myosin II accumulated. This polarity generation for migration does not require the contraction of actomyosin. PMID:23442953

  4. Gdt2 regulates the transition of Dictyostelium cells from growth to differentiation

    Directory of Open Access Journals (Sweden)

    Anjard Christophe

    2004-07-01

    Full Text Available Abstract Background Dictyostelium life cycle consists of two distinct phases – growth and development. The control of growth-differentiation transition in Dictyostelium is not completely understood, and only few genes involved in this process are known. Results We have isolated a REMI (restriction enzyme-mediated integration mutant, which prematurely initiates multicellular development. When grown on a bacterial lawn, these cells aggregate before the bacteria are completely cleared. In bacterial suspension, mutant cells express the developmental marker discoidin Iγ even at low cell densities and high concentrations of bacteria. In the absence of nutrients, mutant cells aggregate more rapidly than wild type, but the rest of development is unaffected and normal fruiting bodies are formed. The disrupted gene shows substantial homology to the recently described gdt1 gene, and therefore was named gdt2. While GDT1 and GDT2 are similar in many ways, there are intriguing differences. GDT2 contains a well conserved protein kinase domain, unlike GDT1, whose kinase domain is probably non-functional. The gdt2 and gdt1 mRNAs are regulated differently, with gdt2 but not gdt1 expressed throughout development. The phenotypes of gdt2- and gdt1- mutants are related but not identical. While both initiate development early, gdt2- cells grow at a normal rate, unlike gdt1- mutants. Protein kinase A levels and activity are essentially normal in growing gdt2- mutants, implying that GDT2 regulates a pathway that acts separately from PKA. Gdt1 and gdt2 are the first identified members of a family containing at least eight closely related genes. Conclusions We have isolated and characterised a new gene, gdt2, which acts to restrain development until conditions are appropriate. We also described a family of related genes in the Dictyostelium genome. We hypothesise that different family members might control similar cellular processes, but respond to different

  5. Ras Proteins Have Multiple Functions in Vegetative Cells of Dictyostelium

    OpenAIRE

    Bolourani, Parvin; Spiegelman, George; Weeks, Gerald

    2010-01-01

    During the aggregation of Dictyostelium cells, signaling through RasG is more important in regulating cyclic AMP (cAMP) chemotaxis, whereas signaling through RasC is more important in regulating the cAMP relay. However, RasC is capable of substituting for RasG for chemotaxis, since rasG− cells are only partially deficient in chemotaxis, whereas rasC−/rasG− cells are totally incapable of chemotaxis. In this study we have examined the possible functional overlap between RasG and RasC in vegetat...

  6. Dicty_cDB: SSH163 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ---lykilvvgdigtw*tsiikrfvhnifsmhykstigvdfalkvinwdpknrs*itimg ycrsrkiwindksll*rsswsndyi*cy*neyi*ssc*mesry*f*...RNA, complete cds. 46 3e-10 4 AC117075 |AC117075.2 Dictyostelium discoideum chromosome 2 map 5201047-5455781... strain AX4, complete sequence. 46 8e-07 9 AC116920 |AC116920.2 Dictyostelium discoideum chromosome 2 map 38...quence. 42 1e-05 3 AC117080 |AC117080.2 Dictyostelium discoideum chromosome 2 map complement(821514-735598)

  7. Dicty_cDB: VHI341 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available iscoideum cDNA clone:ddv51k15, 3' ... 1447 0.0 1 ( BJ442773 ) Dictyostelium discoideum cDNA clone:ddv50...m24, 3' ... 1447 0.0 1 ( BJ442764 ) Dictyostelium discoideum cDNA clone:ddv50l21, 3' ...... 1447 0.0 1 ( BJ442731 ) Dictyostelium discoideum cDNA clone:ddv50e24, 3' ... 1447 0.0 1 ( BJ442218 ) Dict

  8. Dicty_cDB: VHK894 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available iscoideum cDNA clone:ddv51k15, 3' ... 1467 0.0 1 ( BJ442773 ) Dictyostelium discoideum cDNA clone:ddv50m24, ...3' ... 1467 0.0 1 ( BJ442764 ) Dictyostelium discoideum cDNA clone:ddv50l21, 3' ... 1467 0.0 1 ( BJ442731 ) ...Dictyostelium discoideum cDNA clone:ddv50e24, 3' ... 1467 0.0 1 ( BJ442218 ) Dict

  9. Dicty_cDB: VHH260 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ideum cDNA clone:ddv54o16, 5' ... 1090 0.0 1 ( BJ423883 ) Dictyostelium discoideum cDNA clone:ddv50...o17, 5' ... 1090 0.0 1 ( BJ423839 ) Dictyostelium discoideum cDNA clone:ddv50g15, 5' ... 1...090 0.0 1 ( BJ423765 ) Dictyostelium discoideum cDNA clone:ddv50g12, 5' ... 1090 0.0 1 ( BJ423178 ) Dictyost

  10. Dicty_cDB: VHO133 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available deum cDNA clone:ddv59a09, 3' ... 1411 0.0 1 ( BJ442525 ) Dictyostelium discoideum cDNA clone:ddv50...l04, 3' ... 1292 0.0 2 ( BJ442499 ) Dictyostelium discoideum cDNA clone:ddv50g01, 3' ... 12..., 3' ... 1233 0.0 2 ( BJ442653 ) Dictyostelium discoideum cDNA clone:ddv50f18, 3' ... 1225 0.0 3 ( C25574 )

  11. Dicty_cDB: VFD730 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available omology vs DNA Score E Sequences producing significant alignments: (bits) Value N AF305060 |AF305060.1 Dictyostelium discoideum Wisco...otein Score E Sequences producing significant alignments: (bits) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wisco...tt-Aldrich syndrome protein (wasA) gene, complete cds. 4...tt-A... 83 3e-15 AC117076_18( AC117076 |pid:none) Dictyostelium discoideum chromoso

  12. Dicty_cDB: VHG547 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available C: tatnykw*ctkscein*fnythfkiiwciwtfw*****ytiidisnysskw*kytnak** wysfikcrwindysrfirftifkqftictiircfkystlysyt...lium discoideum cDNA clone:dda53e21, 5' ... 1191 0.0 1 ( AC116984 ) Dictyostelium discoideum chromosome 2 ma

  13. Dicty_cDB: VSH237 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available elium discoideum small aggregate formation ... 54 0.007 1 ( M19469 ) Dictyostelium discoideum 109 gene 3, co...tyostelium citrinum mitochondrion, complete ge... 115 2e-40 3 ( U48706 ) Dictyost

  14. Parasexual genetics of Dictyostelium gene disruptions: identification of a ras pathway using diploids

    Directory of Open Access Journals (Sweden)

    Insall Robert H

    2003-07-01

    Full Text Available Abstract Background The relative ease of targeted gene disruption in the social amoeba Dictyostelium has stimulated its widespread use as an experimental organism for cell and developmental biology. However, the field has been hamstrung by the lack of techniques to recombine disrupted genes. Results We describe new techniques for parasexual fusion of strains in liquid medium, selection and maintenance of the resulting stable diploid strains, and segregation to make recombined haploids. We have used these techniques to isolate rasS/gefB double nulls. The phenotypes of these mutants are no more severe than either parent, with movement, phagocytosis and fluid-phase endocytosis affected to the same degree as in rasS or gefB single nulls. In addition, we have produced diploids from one AX2- and one AX3-derived parent, providing an axenic strain with fewer secondary phenotypes than has been previously available. Conclusions The phenotype of the rasS/gefB double mutant suggests that the RasS and GefB proteins lie on the same linear pathway. In addition, axenic diploids and the techniques to generate, maintain and segregate them will be productive tools for future work on Dictyostelium. They will particularly facilitate generation of multiple mutants and manuipulation of essential genes.

  15. Adenylyl cyclase localization to the uropod of aggregating Dictyostelium cells requires RacC

    Science.gov (United States)

    Wang, C.; Jung, D.; Cao, Z.; Chung, C. Y.

    2015-01-01

    The localization of adenylyl cyclase A (ACA) to uropod of cells is required for the stream formation during Dictyostelium development. RacC is a Dictyostelium orthologue of Cdc42. We identified a streaming defect of racC− cells as they are clearly less polarized and form smaller and fragmented streams. ACA-YFP is mainly associated with intracellular vesicular structures, but not with the plasma membrane in racC− cells. racC− cells have a slightly higher number of vesicles than Ax3 cells, suggesting that the defect of ACA trafficking is not simply due to the lack of vesicle formation. While the ACA-YFP vesicles traveled with an average velocity of 9.1 µm/min in Ax3 cells, a slow and diffusional movement without direction with an average velocity of 4 µm/min was maintained in racC− cells. Images acquired by using total internal reflection fluorescence (TIRF) microscopy and fluorescence recovery after photobleaching (FRAP) analysis revealed that a significantly decreased number of ACA-YFP vesicles appeared near the cell membrane, indicating a defect in ACA-YFP vesicle trafficking. These results suggest an important role of RacC in the rapid and directional movements of ACA vesicles on microtubules to the plasma membrane, especially to the back of polarized cell. PMID:26315268

  16. Dictyostelium myosin bipolar thick filament formation: importance of charge and specific domains of the myosin rod.

    Directory of Open Access Journals (Sweden)

    Daniel Hostetter

    2004-11-01

    Full Text Available Myosin-II thick filament formation in Dictyostelium is an excellent system for investigating the phenomenon of self-assembly, as the myosin molecule itself contains all the information required to form a structure of defined size. Phosphorylation of only three threonine residues can dramatically change the assembly state of myosin-II. We show here that the C-terminal 68 kDa of the myosin-II tail (termed AD-Cterm assembles in a regulated manner similar to full-length myosin-II and forms bipolar thick filament (BTF structures when a green fluorescent protein (GFP "head" is added to the N terminus. The localization of this GFP-AD-Cterm to the cleavage furrow of dividing Dictyostelium cells depends on assembly state, similar to full-length myosin-II. This tail fragment therefore represents a good model system for the regulated formation and localization of BTFs. By reducing regulated BTF assembly to a more manageable model system, we were able to explore determinants of myosin-II self-assembly. Our data support a model in which a globular head limits the size of a BTF, and the large-scale charge character of the AD-Cterm region is important for BTF formation. Truncation analysis of AD-Cterm tail fragments shows that assembly is delicately balanced, resulting in assembled myosin-II molecules that are poised to disassemble due to the phosphorylation of only three threonines.

  17. Differentiation induced by physiological and pharmacological stimuli leads to increased antigenicity of human neuroblastoma cells

    Institute of Scientific and Technical Information of China (English)

    Lena-Maria Carlson; Sven P(a)hlman; Anna De Geer; Per Kogner; Jelena Levitskaya

    2008-01-01

    Sympathetic neuronal differentiation is associated with favorable prognosis of neuroblastoma (NB), the most common extra-cranial solid tumor of early childhood. Differentiation agents have proved useful in clinical protocols of NB treatment, but using them as a sole treatment is not sufficient to induce tumor elimination in patients. Therefore, complementary approaches, such as immunotherapy, are warranted. Here we demonstrate that differentiation of NB cell lines and ex vivo isolated tumor cells in response to physiological or pharmacological stimuli is associated with acquisition of increased antigenicity. This manifests as increased expression of surface major histocompatibility class I complexes and ICAM-1 molecules and translates into increased sensitivity of NB cells to lysis by cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. The latter is paralleled by enhanced ability of differentiated cells to form immune conjugates and bind increased amounts of granzyme B to the cell surface. We demonstrate, for the first time, that, regardless of the stimulus applied, the differentiation state in NBs is associated with increased tumor antigenicity that enables more efficient elimination of tumor cells by cytotoxic lymphocytes and paves the way for combined application of differentiation-inducing agents and immunotherapy as an auxiliary approach in NB patients.

  18. Relationship between Adaptation of the Folic Acid and the cAMP Mediated cGMP Response in Dictyostelium

    NARCIS (Netherlands)

    Haastert, Peter J.M. van

    1983-01-01

    Chemotactic stimulation of post-vegetative Dictyostelium cells with folic acid or aggregative cells with cAMP results in a fast transient cGMP response which peaks at 10 s; basal levels are recovered in about 30-40 s. Stimulation with folic acid or cAMP rapidly desensitizes the cells for equal or lo

  19. A Novel, Phospholipase C-independent Pathway of Inositol 1,4,5-Trisphosphate Formation in Dictyostelium and Rat Liver

    NARCIS (Netherlands)

    Dijken, Peter van; Haas, Jan-Roelof de; Craxton, Andrew; Erneux, Christophe; Shears, Stephen B.; Haastert, Peter J.M. van

    1995-01-01

    In an earlier study a mutant Dictyostelium cell-line (plc(-)) was constructed in which all phospholipase C activity was disrupted and nonfunctional, yet these cells had nearly normal Ins(1,4,5)P-3 levels (Drayer, A. L., Van Der Kaay, J., Mayr, G. W, Van Haastert, P. J. M. (1990) EMBO J. 13, 1601-160

  20. Nucleus-associated phosphorylation of Ins(1,4,5)P3 to InsP6 in Dictyostelium

    NARCIS (Netherlands)

    Kaay, Jeroen van der; Wesseling, Jelle; Haastert, Peter J.M. van

    1995-01-01

    Although many cells contain large amounts of InsP(6), its metabolism and function is still largely unknown. In Dictyostelium lysates, the formation of InsP(6) by sequential phosphorylation of inositol via Ins(3,4,6)P-3 has been described [Stevens and Irvine (1990) Nature (London) 346, 580-583]; the

  1. The role of cGMP and the rear of the cell in Dictyostelium chemotaxis and cell streaming

    NARCIS (Netherlands)

    Veltman, Douwe M.; van Haastert, Peter J. M.

    2008-01-01

    During chemotaxis, pseudopod extensions lead the cell towards the source of attractant. The role of actin-filled pseudopodia at the front of the cell is well recognized, whereas the function of the rear of the cell in chemotaxis and cell-cell interactions is less well known. Dictyostelium cell

  2. Dicty_cDB: Contig-U15415-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 14 2 ( AC116957 ) Dictyostelium discoideum chromosome 2 map 1685067... 36 0.016 15 ( EE674606 ) EST1343 Mycelia Grown in Nitrogen Lim...ited Media C... 48 0.027 2 ( BJ426778 ) Dictyostelium di

  3. Dicty_cDB: SSC219 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available gy vs DNA Score E Sequences producing significant alignments: (bits) Value N AC116984 |AC116984.2 Dictyostelium discoideum chromo....2 Dictyostelium discoideum chromosome 2 map 1004546-1005075 strain AX4, complete... sequence. 42 0.051 2 AC116955 |AC116955.2 Dictyostelium discoideum chromosome 2 map 5455881-5481449 strain ...AX4, complete sequence. 46 0.054 3 AC114261 |AC114261.2 Dictyostelium discoideum chromosome 2 map 126059-159...710 strain AX4, complete sequence. 46 0.37 1 AC006278 |AC006278.8 Plasmodium falciparum chromosome 12 clone

  4. Dicty_cDB: CHG664 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available q*i knqv*vwh**imkiiilvghlq--- ---inskcfnifi*yyk*kwindtnfsrd*il*k*kkn*icrsrnynetiin*iynly*s isifnkiesitinyish...oducing significant alignments: (bits) Value N AC116957 |AC116957.2 Dictyostelium discoideum chromosome 2 ma...p 1685067-2090751 strain AX4, complete sequence. 38 7e-16 29 AC116963 |AC116963.2 Dictyostelium discoideum chromo...2 Dictyostelium discoideum chromosome 2 map 3622643-3879522 strain AX4, complete sequence. 40 6e-15 26 AL844...506 |AL844506.1 Plasmodium falciparum chromosome 7. 36 1e-14 33 AC117075 |AC117075.2 Dictyostelium discoideum chromo

  5. Dicty_cDB: VHJ572 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available nts: (bits) Value N ( BJ442697 ) Dictyostelium discoideum cDNA clone:ddv50o17, 3' ... 1703 0.0 1 ( BJ438083 ...) Dictyostelium discoideum cDNA clone:ddv36f08, 3' ... 1641 0.0 2 ( BJ442531 ) Dictyostelium discoideum cDNA clone:ddv50...1578 0.0 3 ( BJ442656 ) Dictyostelium discoideum cDNA clone:ddv50g15, 3' ... 1574 0.0 3 dna update 2008.11.1

  6. Dicty_cDB: VHN532 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 0 1 ( BJ445359 ) Dictyostelium discoideum cDNA clone:ddv59a09, 3' ... 950 0.0 1 ( BJ442525 ) Dictyostelium d...iscoideum cDNA clone:ddv50l04, 3' ... 950 0.0 1 ( BJ442499 ) Dictyostelium discoideum cDNA clone:ddv50g01, 3... 3' ... 932 0.0 1 ( BJ442653 ) Dictyostelium discoideum cDNA clone:ddv50f18, 3' ... 904 0.0 2 dna update 200

  7. Varicella-Zoster Virus glycoprotein expression differentially induces the unfolded protein response in infected cells.

    Directory of Open Access Journals (Sweden)

    John Earl Carpenter

    2014-07-01

    Full Text Available Varicella-zoster virus (VZV is a human herpesvirus that spreads to children as varicella or chicken pox. The virus then establishes latency in the nervous system and re-emerges, typically decades later, as zoster or shingles. We have reported previously that VZV induces autophagy in infected cells as well as exhibiting evidence of the Unfolded Protein Response (UPR: XBP1 splicing, a greatly expanded Endoplasmic Reticulum (ER and CHOP expression. Herein we report the results of a UPR specific PCR array that measures the levels of mRNA of 84 different components of the UPR in VZV infected cells as compared to tunicamycin treated cells as a positive control and uninfected, untreated cells as a negative control. Tunicamycin is a mixture of chemicals that inhibits N-linked glycosylation in the ER with resultant protein misfolding and the UPR. We found that VZV differentially induces the UPR when compared to tunicamycin treatment. For example, tunicamycin treatment moderately increased (8 fold roughly half of the array elements while downregulating only three (one ERAD and two FOLD components. VZV infection on the other hand upregulated 33 components including a little described stress sensor CREB-H (64 fold as well as ER membrane components INSIG and gp78, which modulate cholesterol synthesis while downregulating over 20 components mostly associated with ERAD and FOLD. We hypothesize that this expression pattern is associated with an expanding ER with downregulation of active degradation by ERAD and apoptosis as the cell attempts to handle abundant viral glycoprotein synthesis.

  8. Interleukin-17A Differentially Induces Inflammatory and Metabolic Gene Expression in the Adipose Tissues of Lean and Obese Mice.

    Science.gov (United States)

    Qu, Yine; Zhang, Qiuyang; Ma, Siqi; Liu, Sen; Chen, Zhiquan; Mo, Zhongfu; You, Zongbing

    2016-04-07

    The functions of interleukin-17A (IL-17A) in adipose tissues and adipocytes have not been well understood. In the present study, male mice were fed with a regular diet (n = 6, lean mice) or a high-fat diet (n = 6, obese mice) for 30 weeks. Subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) were analyzed for IL-17A levels. SAT and VAT were treated with IL-17A and analyzed for inflammatory and metabolic gene expression. Mouse 3T3-L1 pre-adipocytes were differentiated into adipocytes, followed with IL-17A treatment and analysis for inflammatory and metabolic gene expression. We found that IL-17A levels were higher in obese SAT than lean SAT; the basal expression of inflammatory and metabolic genes was different between SAT and VAT and between lean and obese adipose tissues. IL-17A differentially induced expression of inflammatory and metabolic genes, such as tumor necrosis factor α, Il-6, Il-1β, leptin, and glucose transporter 4, in adipose tissues of lean and obese mice. IL-17A also differentially induced expression of inflammatory and metabolic genes in pre-adipocytes and adipocytes, and IL-17A selectively activated signaling pathways in adipose tissues and adipocytes. These findings suggest that IL-17A differentially induces inflammatory and metabolic gene expression in the adipose tissues of lean and obese mice.

  9. Interleukin-17A Differentially Induces Inflammatory and Metabolic Gene Expression in the Adipose Tissues of Lean and Obese Mice

    Directory of Open Access Journals (Sweden)

    Yine Qu

    2016-04-01

    Full Text Available The functions of interleukin-17A (IL-17A in adipose tissues and adipocytes have not been well understood. In the present study, male mice were fed with a regular diet (n = 6, lean mice or a high-fat diet (n = 6, obese mice for 30 weeks. Subcutaneous adipose tissue (SAT and visceral adipose tissue (VAT were analyzed for IL-17A levels. SAT and VAT were treated with IL-17A and analyzed for inflammatory and metabolic gene expression. Mouse 3T3-L1 pre-adipocytes were differentiated into adipocytes, followed with IL-17A treatment and analysis for inflammatory and metabolic gene expression. We found that IL-17A levels were higher in obese SAT than lean SAT; the basal expression of inflammatory and metabolic genes was different between SAT and VAT and between lean and obese adipose tissues. IL-17A differentially induced expression of inflammatory and metabolic genes, such as tumor necrosis factor α, Il-6, Il-1β, leptin, and glucose transporter 4, in adipose tissues of lean and obese mice. IL-17A also differentially induced expression of inflammatory and metabolic genes in pre-adipocytes and adipocytes, and IL-17A selectively activated signaling pathways in adipose tissues and adipocytes. These findings suggest that IL-17A differentially induces inflammatory and metabolic gene expression in the adipose tissues of lean and obese mice.

  10. Dicty_cDB: VHK896 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available oideum cDNA clone:ddv52p24, 3' ... 1677 0.0 1 ( BJ442531 ) Dictyostelium discoideum cDNA clone:ddv50m05, 3' ...telium discoideum cDNA clone:ddv60e18, 3' ... 1610 0.0 2 ( BJ442697 ) Dictyostelium discoideum cDNA clone:ddv50...o17, 3' ... 1610 0.0 1 ( BJ442656 ) Dictyostelium discoideum cDNA clone:ddv50g15, 3' ... 1610 0.0 2 ( BJ4...2 ) Dictyostelium discoideum cDNA clone:ddv31b11, 3' ... 1584 0.0 2 ( BJ442583 ) Dictyostelium discoideum cDNA clone:ddv50

  11. Postaggregative differentiation induction by cyclic AMP in Dictyostelium: intracellular transduction pathway and requirement for additional stimuli.

    Science.gov (United States)

    Schaap, P; Van Lookeren Campagne, M M; Van Driel, R; Spek, W; Van Haastert, P J; Pinas, J

    1986-11-01

    Cyclic AMP induces postaggregative differentiation in aggregation competent cells of Dictyostelium by interacting with cell surface cAMP receptors. We investigated the transduction pathway of this response and additional requirements for the induction of postaggregative differentiation. Optimal induction of postaggregative gene expression requires that vegetative cells are first exposed to 2-4 hr of nanomolar cAMP pulses, and subsequently for 4-6 hr to steady-state cAMP concentrations in the micromolar range. Cyclic AMP pulses, which are endogenously produced before and during aggregation, induce full responsiveness to cAMP as a morphogen. The transduction pathway from the cell surface cAMP receptor to postaggregative gene expression may involve Ca2+ ions as intracellular messengers. A cAMP-induced increase in intracellular cAMP or cGMP levels is not involved in the transduction pathway.

  12. Expression of activated Ras during Dictyostelium development alters cell localization and changes cell fate.

    Science.gov (United States)

    Jaffer, Z M; Khosla, M; Spiegelman, G B; Weeks, G

    2001-03-01

    There is now a body of evidence to indicate that Ras proteins play important roles in development. Dictyostelium expresses several ras genes and each appears to perform a distinct function. Previous data had indicated that the overexpression of an activated form of the major developmentally regulated gene, rasD, caused a major aberration in morphogenesis and cell type determination. We now show that the developmental expression of an activated rasG gene under the control of the rasD promoter causes a similar defect. Our results indicate that the expression of activated rasG in prespore cells results in their transdifferentiation into prestalk cells, whereas activated rasG expression in prestalk causes gross mislocalization of the prestalk cell populations.

  13. Dicty_cDB: [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Value N U66367 |U66367.1 Dictyostelium discoideum SapA (sapA) mRNA, partial cds. 1195 0.0 1 AC115599 |AC115599.2 Dictyostelium di... 60 4e-05 1 AC115684 |AC115684.2 Dictyostelium discoideum chromosome 2 map 3108975-3191114 strain AX4, compl...ete sequence. 60 4e-05 1 AC114261 |AC114261.2 Dictyostelium discoideum chromosome... 2 map 126059-159710 strain AX4, complete sequence. 60 4e-05 1 AC116551 |AC116551.2 Dictyostelium discoideum...lue U66367_1( U66367 |pid:none) Dictyostelium discoideum SapA (sapA) m... 385 e-105 AF196308_1( AF196308 |pi

  14. Dicty_cDB: [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ctyostelium discoideum cysteine proteinase (cprG) mRNA, complete cds. 650 0.0 5 U72745 |U72745.1 Dictyostelium di...scoideum cysteine proteinase (cprF) mRNA, complete cds. 484 0.0 8 L36205 |L36205.1 Dictyostelium di...scoideum cysteine proteinase CP5 mRNA, complete cds. 145 2e-74 5 AC117072 |AC117072.2 Dictyostelium di...4e-68 9 L36204 |L36204.1 Dictyostelium discoideum cysteine proteinase (CP4) mRNA, complete cds. 117 1e-67 5 X03344 |X03344.1 Di...ctyostelium discoideum mRNA for cysteine proteinase 2. 82 1e-11 1 M16039 |M16039.1 Dictyostelium di

  15. Genome-wide transcriptional changes induced by phagocytosis or growth on bacteria in Dictyostelium

    Directory of Open Access Journals (Sweden)

    Peracino Barbara

    2008-06-01

    Full Text Available Abstract Background Phagocytosis plays a major role in the defense of higher organisms against microbial infection and provides also the basis for antigen processing in the immune response. Cells of the model organism Dictyostelium are professional phagocytes that exploit phagocytosis of bacteria as the preferred way to ingest food, besides killing pathogens. We have investigated Dictyostelium differential gene expression during phagocytosis of non-pathogenic bacteria, using DNA microarrays, in order to identify molecular functions and novel genes involved in phagocytosis. Results The gene expression profiles of cells incubated for a brief time with bacteria were compared with cells either incubated in axenic medium or growing on bacteria. Transcriptional changes during exponential growth in axenic medium or on bacteria were also compared. We recognized 443 and 59 genes that are differentially regulated by phagocytosis or by the different growth conditions (growth on bacteria vs. axenic medium, respectively, and 102 genes regulated by both processes. Roughly one third of the genes are up-regulated compared to macropinocytosis and axenic growth. Functional annotation of differentially regulated genes with different tools revealed that phagocytosis induces profound changes in carbohydrate, aminoacid and lipid metabolism, and in cytoskeletal components. Genes regulating translation and mitochondrial biogenesis are mostly up-regulated. Genes involved in sterol biosynthesis are selectively up-regulated, suggesting a shift in membrane lipid composition linked to phagocytosis. Very few changes were detected in genes required for vesicle fission/fusion, indicating that the intracellular traffic machinery is mostly in common between phagocytosis and macropinocytosis. A few putative receptors, including GPCR family 3 proteins, scaffolding and adhesion proteins, components of signal transduction and transcription factors have been identified, which could

  16. The Cyclase-associated Protein CAP as Regulator of Cell Polarity and cAMP Signaling in Dictyostelium

    OpenAIRE

    Noegel, Angelika A; Blau-Wasser, Rosemarie; Sultana, Hameeda; Müller, Rolf; Israel, Lars; Schleicher, Michael; Patel, Hitesh; Weijer, Cornelis J

    2004-01-01

    Cyclase-associated protein (CAP) is an evolutionarily conserved regulator of the G-actin/F-actin ratio and, in yeast, is involved in regulating the adenylyl cyclase activity. We show that cell polarization, F-actin organization, and phototaxis are altered in a Dictyostelium CAP knockout mutant. Furthermore, in complementation assays we determined the roles of the individual domains in signaling and regulation of the actin cytoskeleton. We studied in detail the adenylyl cyclase activity and fo...

  17. The cyclase-associated protein CAP as regulator of cell polarity and cAMP signaling in Dictyostelium.

    Science.gov (United States)

    Noegel, Angelika A; Blau-Wasser, Rosemarie; Sultana, Hameeda; Müller, Rolf; Israel, Lars; Schleicher, Michael; Patel, Hitesh; Weijer, Cornelis J

    2004-02-01

    Cyclase-associated protein (CAP) is an evolutionarily conserved regulator of the G-actin/F-actin ratio and, in yeast, is involved in regulating the adenylyl cyclase activity. We show that cell polarization, F-actin organization, and phototaxis are altered in a Dictyostelium CAP knockout mutant. Furthermore, in complementation assays we determined the roles of the individual domains in signaling and regulation of the actin cytoskeleton. We studied in detail the adenylyl cyclase activity and found that the mutant cells have normal levels of the aggregation phase-specific adenylyl cyclase and that receptor-mediated activation is intact. However, cAMP relay that is responsible for the generation of propagating cAMP waves that control the chemotactic aggregation of starving Dictyostelium cells was altered, and the cAMP-induced cGMP production was significantly reduced. The data suggest an interaction of CAP with adenylyl cyclase in Dictyostelium and an influence on signaling pathways directly as well as through its function as a regulatory component of the cytoskeleton.

  18. Src1 is a Protein of the Inner Nuclear Membrane Interacting with the Dictyostelium Lamin NE81

    Directory of Open Access Journals (Sweden)

    Petros Batsios

    2016-03-01

    Full Text Available The nuclear envelope (NE consists of the outer and inner nuclear membrane (INM, whereby the latter is bound to the nuclear lamina. Src1 is a Dictyostelium homologue of the helix-extension-helix family of proteins, which also includes the human lamin-binding protein MAN1. Both endogenous Src1 and GFP-Src1 are localized to the NE during the entire cell cycle. Immuno-electron microscopy and light microscopy after differential detergent treatment indicated that Src1 resides in the INM. FRAP experiments with GFP-Src1 cells suggested that at least a fraction of the protein could be stably engaged in forming the nuclear lamina together with the Dictyostelium lamin NE81. Both a BioID proximity assay and mis-localization of soluble, truncated mRFP-Src1 at cytosolic clusters consisting of an intentionally mis-localized mutant of GFP-NE81 confirmed an interaction of Src1 and NE81. Expression GFP-Src11–646, a fragment C-terminally truncated after the first transmembrane domain, disrupted interaction of nuclear membranes with the nuclear lamina, as cells formed protrusions of the NE that were dependent on cytoskeletal pulling forces. Protrusions were dependent on intact microtubules but not actin filaments. Our results indicate that Src1 is required for integrity of the NE and highlight Dictyostelium as a promising model for the evolution of nuclear architecture.

  19. NCBI nr-aa BLAST: CBRC-DDIS-01-0111 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-01-0111 ref|XP_646081.1| alkaline dihydroceramidase [Dictyostelium discoi...deum AX4] gb|EAL72137.1| alkaline dihydroceramidase [Dictyostelium discoideum AX4] XP_646081.1 1e-164 100% ...

  20. Dicty_cDB: SSI861 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available cs*yilyal*inhwcrfciksd*lgsknrs*itimgycrsr kiwindksll*rsswsndyi*cy*neyi*ssc*mesry*f*snlwcr*ktnsssfiskqm *fr*r...075 |AC117075.2 Dictyostelium discoideum chromosome 2 map 5201047-5455781 strain AX4, complete sequence. 46 ...6e-07 9 AC116920 |AC116920.2 Dictyostelium discoideum chromosome 2 map 3879572-4071762 strain AX4, complete

  1. Dicty_cDB: VFL110 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available PTE MVENATSKLDEMIMEYHNTSPTSSPTNTRKSITPVQQQQ--- ---ttnsttnsttnsttnsttttttnstn*sssknd***n**nwinddirtkhiitklds ...... 56 0.003 1 ( AC116979 ) Dictyostelium discoideum chromosome 2 map 6445720... 32 0.010 15 ( AC117070 ) Di...ctyostelium discoideum chromosome 2 map 2097701... 36 0.012 10 ( CZ964675 ) 16308

  2. NCBI nr-aa BLAST: CBRC-DDIS-05-0159 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-05-0159 ref|XP_635241.1| putative cationic amino acid transporter [Dictyo...stelium discoideum AX4] gb|EAL61597.1| putative cationic amino acid transporter [Dictyostelium discoideum AX4] XP_635241.1 1e-122 83% ...

  3. Dicty_cDB: SFK250 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Value U57081_2( U57081 |pid:none) Dictyostelium discoideum Tdd-4 transpo... 225 3e-58 U57081_1( U57081 |pid...:none) Dictyostelium discoideum Tdd-4 transpo... 225 3e-58 AJ893357_41( AJ893357

  4. Dicty_cDB: SLI455 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available gnments: (bits) Value U57081_2( U57081 |pid:none) Dictyostelium discoideum Tdd-4 transpo... 35 0.73 U57081_1...( U57081 |pid:none) Dictyostelium discoideum Tdd-4 transpo... 35 0.73 AE010299_2794( AE010299 |pid:none) Met

  5. Dicty_cDB: SSD460 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available cing significant alignments: (bits) Value N ( BJ325867 ) Dictyostelium discoideum cDNA clone:dda2o13, 5' e....... 583 0.0 3 ( BJ340556 ) Dictyostelium discoideum cDNA clone:dda2o13, 3' e... 583 0.0 3 dna update 2009. 7.

  6. Dicty_cDB: Contig-U12991-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ( AF272150 ) Dictyostelium discoideum deliriumA (dlrA) gene, c... 2022 0.0 3 ( BJ...39594 ) TT1EP48TV Tetrahymena thermophila SB210 cDNA libr... 38 10.0 2 >( AF272150 ) Dictyostelium discoideum delirium

  7. NCBI nr-aa BLAST: CBRC-DDIS-03-0190 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-03-0190 ref|XP_646956.1| ARID/BRIGHT DNA binding domain-containing protei...n [Dictyostelium discoideum AX4] gb|EAL72978.1| ARID/BRIGHT DNA binding domain-containing protein [Dictyostelium discoideum AX4] XP_646956.1 1e-06 23% ...

  8. NCBI nr-aa BLAST: CBRC-DDIS-02-0179 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-02-0179 ref|XP_643823.1| cell differentiation family, Rcd1-like protein [...Dictyostelium discoideum AX4] gb|EAL69925.1| cell differentiation family, Rcd1-like protein [Dictyostelium discoideum AX4] XP_643823.1 0.0 98% ...

  9. NCBI nr-aa BLAST: CBRC-DDIS-04-0102 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-04-0102 ref|XP_643823.1| cell differentiation family, Rcd1-like protein [...Dictyostelium discoideum AX4] gb|EAL69925.1| cell differentiation family, Rcd1-like protein [Dictyostelium discoideum AX4] XP_643823.1 3e-59 30% ...

  10. NCBI nr-aa BLAST: CBRC-DDIS-03-0185 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-03-0185 ref|XP_643823.1| cell differentiation family, Rcd1-like protein [...Dictyostelium discoideum AX4] gb|EAL69925.1| cell differentiation family, Rcd1-like protein [Dictyostelium discoideum AX4] XP_643823.1 1e-67 33% ...

  11. Dicty_cDB: SLH619 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ation factor. 513 e-148 2 ( AU284246 ) Dictyostelium discoideum gamete cDNA clone:F...4 Homology vs DNA Score E Sequences producing significant alignments: (bits) Value N ( X15430 ) Dictyostelium discoideum mRNA for gel

  12. Dicty_cDB: VSI339 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ogy vs CSM-cDNA Score E Sequences producing significant alignments: (bits) Value VSI339 (VSI339Q) /CSM/VS/VS...nces producing significant alignments: (bits) Value N ( AC116330 ) Dictyostelium discoideum chromosome 2 map...ficant alignments: (bits) Value AC116330_20( AC116330 |pid:none) Dictyostelium discoideum chromoso... 48 1e-

  13. NCBI nr-aa BLAST: CBRC-DDIS-02-0191 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-02-0191 ref|XP_643409.1| natural resistance-associated macrophage protein... (NRAMP) [Dictyostelium discoideum AX4] gb|EAL69658.1| natural resistance-associated macrophage protein (NRAMP) [Dictyostelium discoideum AX4] XP_643409.1 0.0 100% ...

  14. NCBI nr-aa BLAST: CBRC-DMEL-08-0001 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DMEL-08-0001 ref|XP_640618.1| hypothetical protein DDBDRAFT_0204646 [Dictyoste...lium discoideum AX4] gb|EAL66636.1| hypothetical protein DDBDRAFT_0204646 [Dictyostelium discoideum AX4] XP_640618.1 2e-40 89% ...

  15. NCBI nr-aa BLAST: CBRC-DMEL-08-0035 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DMEL-08-0035 ref|XP_640618.1| hypothetical protein DDBDRAFT_0204646 [Dictyoste...lium discoideum AX4] gb|EAL66636.1| hypothetical protein DDBDRAFT_0204646 [Dictyostelium discoideum AX4] XP_640618.1 2e-40 89% ...

  16. NCBI nr-aa BLAST: CBRC-DMEL-08-0002 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DMEL-08-0002 ref|XP_640618.1| hypothetical protein DDBDRAFT_0204646 [Dictyoste...lium discoideum AX4] gb|EAL66636.1| hypothetical protein DDBDRAFT_0204646 [Dictyostelium discoideum AX4] XP_640618.1 2e-40 89% ...

  17. NCBI nr-aa BLAST: CBRC-TGUT-04-0054 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-TGUT-04-0054 ref|XP_640618.1| hypothetical protein DDBDRAFT_0204646 [Dictyoste...lium discoideum AX4] gb|EAL66636.1| hypothetical protein DDBDRAFT_0204646 [Dictyostelium discoideum AX4] XP_640618.1 1e-20 61% ...

  18. NCBI nr-aa BLAST: CBRC-DDIS-03-0191 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-03-0191 ref|XP_640618.1| hypothetical protein DDBDRAFT_0204646 [Dictyoste...lium discoideum AX4] gb|EAL66636.1| hypothetical protein DDBDRAFT_0204646 [Dictyostelium discoideum AX4] XP_640618.1 2e-89 100% ...

  19. Dicty_cDB: VHF669 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available one:ddv60e18, 3' ... 1370 0.0 1 ( BJ442583 ) Dictyostelium discoideum cDNA clone:ddv50g12, 3' ... 1370 0.0 2...coideum cDNA clone:ddv61l04, 3' ... 1368 0.0 2 ( BJ442531 ) Dictyostelium discoideum cDNA clone:ddv50m05, 3'

  20. Dicty_cDB: VHJ615 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available t alignments: (bits) Value N ( BJ423719 ) Dictyostelium discoideum cDNA clone:ddv50m04, 5' ... 989 0.0 2 ( B...NA clone:ddc53g01, 5' ... 678 0.0 3 ( BJ442530 ) Dictyostelium discoideum cDNA clone:ddv50m04, 3' ... 44 0.0

  1. Dicty_cDB: VSI532 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available mete cDNA, clone FC-AE21. 1150 0.0 1 ( BJ442607 ) Dictyostelium discoideum cDNA clone:ddv50m11, 3' ... 1150 ...0.0 1 ( BJ423789 ) Dictyostelium discoideum cDNA clone:ddv50m11, 5' ... 1150 0.0

  2. Dicty_cDB: SLC886 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 3' ... 1298 0.0 1 ( BJ442717 ) Dictyostelium discoideum cDNA clone:ddv50c22, 3' ...... 1298 0.0 1 ( BJ442693 ) Dictyostelium discoideum cDNA clone:ddv50n18, 3' ... 1298 0.0 1 dna update 2009.

  3. Dicty_cDB: VHJ554 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ducing significant alignments: (bits) Value N ( BJ423858 ) Dictyostelium discoideum cDNA clone:ddv50k13, 5' ...30 0.0 2 ( BJ442673 ) Dictyostelium discoideum cDNA clone:ddv50k13, 3' ... 541 e-149 1 ( BJ435821 ) Dictyost

  4. Dicty_cDB: VHJ777 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available es producing significant alignments: (bits) Value N ( BJ423929 ) Dictyostelium discoideum cDNA clone:ddv50...lone:ddv37e22, 5' ... 315 9e-82 1 ( BJ442752 ) Dictyostelium discoideum cDNA clone:ddv50j19, 3' ... 72 2e-08

  5. Dicty_cDB: VHJ883 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available omosome 2 map 3879572... 127 2e-25 1 ( BJ442734 ) Dictyostelium discoideum cDNA clone:ddv50f22, 3' ... 127 2...e-25 1 ( BJ423915 ) Dictyostelium discoideum cDNA clone:ddv50f22, 5' ... 98 2e-16 1 ( BP018838 ) Ciona intes

  6. Dicty_cDB: VHJ672 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available DNA Score E Sequences producing significant alignments: (bits) Value N ( BJ442698 ) Dictyostelium discoideum cDNA clone:ddv50...) Dictyostelium discoideum cDNA clone:ddv50o18, 5' ... 88 1e-18 2 ( BJ416343 ) Di

  7. Dicty_cDB: SLD531 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available . 636 e-178 1 ( BJ423874 ) Dictyostelium discoideum cDNA clone:ddv50n13, 5' ... 636 e-178 1 ( BJ423723 ) Dic...tyostelium discoideum cDNA clone:ddv50n04, 5' ... 636 e-178 1 ( BJ422764 ) Dictyo

  8. Dicty_cDB: VFM293 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 0 1 ( BJ442698 ) Dictyostelium discoideum cDNA clone:ddv50o18, 3' ... 1287 0.0 2 ..... 88 1e-18 2 ( BJ423884 ) Dictyostelium discoideum cDNA clone:ddv50o18, 5' ... 88 1e-18 2 ( BJ416343 ) Dict

  9. Dicty_cDB: Contig-U05350-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available N ( AY392439 ) Dictyostelium discoideum P-selectin gene, complet... 523 e-144 1 ( AC115684 ) Dictyostelium ...ictyostelium discoideum P-selectin gene, complete cds. Length = 5251 Score = 523 ...-01-1... 34 8.5 2 ( EJ313308 ) 1095403247408 Global-Ocean-Sampling_GS-27-01-01-1... 34 8.7 2 >( AY392439 ) D

  10. Dicty_cDB: SFJ736 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 060.1 Dictyostelium discoideum Wiscott-Aldrich syndrome protein (wasA) gene, complete cds. 470 e-129 2 BQ923...1( AF305060 |pid:none) Dictyostelium discoideum Wiscott-A... 81 1e-14 AC117076_18

  11. Dicty_cDB: CFG253 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Value N AF305060 |AF305060.1 Dictyostelium discoideum Wiscott-Aldrich syndrome protein (wasA) gene, complete...ences producing significant alignments: (bits) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott

  12. Dicty_cDB: VSC304 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 05060 |AF305060.1 Dictyostelium discoideum Wiscott-Aldrich syndrome protein (wasA) gene, complete cds. 622 0...bits) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott-A... 167 1e-44 AC117076_18( AC1

  13. Dicty_cDB: SSG705 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available NA Score E Sequences producing significant alignments: (bits) Value N AF305060 |AF305060.1 Dictyostelium discoideum Wiscott...quences producing significant alignments: (bits) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott

  14. Dicty_cDB: CFG349 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available its) Value N AF305060 |AF305060.1 Dictyostelium discoideum Wiscott-Aldrich syndrome protein (wasA) gene, com...060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott-A... 247 4e-64 DQ985464_1( DQ985464 |pid:none) S

  15. Dicty_cDB: SHE721 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available E Sequences producing significant alignments: (bits) Value N AF305060 |AF305060.1 Dictyostelium discoideum Wiscott...305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott-A... 83 8e-15 AC117076_18( AC117076 |pid:none

  16. Dicty_cDB: VSJ735 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available |AF305060.1 Dictyostelium discoideum Wiscott-Aldrich syndrome protein (wasA) gene, complete cds. 436 0.0 5 A... AF305060 |pid:none) Dictyostelium discoideum Wiscott-A... 214 2e-54 BC087802_1( BC087802 |pid:none) Xenopus

  17. Dicty_cDB: SFK712 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available deum cDNA clone:dda5o08, 3' e... 404 e-125 2 ( AF305060 ) Dictyostelium discoideum Wiscott-Aldrich syndrome....ore E Sequences producing significant alignments: (bits) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott

  18. Dicty_cDB: VFA863 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ore E Sequences producing significant alignments: (bits) Value N AF305060 |AF305060.1 Dictyostelium discoideum Wiscott...gnificant alignments: (bits) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott-A... 83

  19. Dicty_cDB: VFN644 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available A clone:ddv28g12, 3' ... 404 0.0 5 ( AF305060 ) Dictyostelium discoideum Wiscott-...ng significant alignments: (bits) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott-A..

  20. Dicty_cDB: SLH341 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 5 ( AF305060 ) Dictyostelium discoideum Wiscott-Aldrich syndrome... 404 0.0 5 ( B...ts) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott-A... 83 8e-15 AC117076_18( AC1170

  1. Dicty_cDB: SFG565 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 5060.1 Dictyostelium discoideum Wiscott-Aldrich syndrome protein (wasA) gene, complete cds. 626 0.0 8 AC1170...bits) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott-A... 254 4e-77 AC117076_18( AC1

  2. Dicty_cDB: SFC789 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ments: (bits) Value N AF305060 |AF305060.1 Dictyostelium discoideum Wiscott-Aldri...ne) Dictyostelium discoideum Wiscott-A... 34 0.031 protein update 2009. 1. 7 PSORT psg: 0.84 gvh: 0.42 alm:

  3. NCBI nr-aa BLAST: CBRC-DDIS-04-0145 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-04-0145 ref|XP_637730.1| structural maintenance of chromosome protein [Di...ctyostelium discoideum AX4] gb|EAL64226.1| structural maintenance of chromosome protein [Dictyostelium discoideum AX4] XP_637730.1 1e-165 96% ...

  4. NCBI nr-aa BLAST: CBRC-DDIS-01-0004 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DDIS-01-0004 ref|XP_647111.1| discoidin-inducing complex (DIC) protein [Dictyo...stelium discoideum AX4] gb|EAL73188.1| discoidin-inducing complex (DIC) protein [Dictyostelium discoideum AX4] XP_647111.1 0.0 100% ...

  5. Mechanism of cAMP-induced H+ -efflux of Dictyostelium cells: a role for fatty acids

    Indian Academy of Sciences (India)

    H Flaadt; R Schaloske; D Malchow

    2000-09-01

    Aggregating Dictyostelium cells release protons when stimulated with cAMP. To find out whether the protons are generated by acidic vesicles or in the cytosol, we permeabilized the cells and found that this did not alter the cAMP-response. Proton efflux in intact cells was inhibited by preincubation with the V-type H+ ATPase inhibitor concanamycin A and with the plasma membrane H+ ATPase blocker miconazole. Surprisingly, miconazole also inhibited efflux in permeabilized cells, indicating that this type of H+ ATPase is present on intracellular vesicles as well. Vesicular acidification was inhibited by miconazole and by concanamycin A, suggesting that the acidic vesicles contain both V-type and P-type H+ ATPases. Moreover, concanamycin A and miconazole acted in concert, both in intact cells and in vesicles. The mechanism of cAMP-induced Ca2+-fluxes involves phospholipase A2 activity. Fatty acids circumvent the plasma membrane and stimulate vesicular Ca2+-efflux. Here we show that arachidonic acid elicited H+-efflux not only from intact cells but also from acidic vesicles. The target of regulation by arachidonic acid seemed to be the vesicular Ca2+-relase channel.

  6. De novo actin polymerization is required for model Hirano body formation in Dictyostelium

    Directory of Open Access Journals (Sweden)

    Yun Dong

    2016-06-01

    Full Text Available Hirano bodies are eosinophilic, actin-rich inclusions found in autopsied brains in numerous neurodegenerative diseases. The mechanism of Hirano body formation is unknown. Mass spectrometry analysis was performed to identify proteins from partially purified model Hirano bodies from Dictyostelium. This analysis identified proteins primarily belonging to ribosomes, proteasomes, mitochondria and cytoskeleton. Profilin, Arp/2/3 and WASH identified by mass spectrometry were found to colocalise with model Hirano bodies. Due to their roles in actin regulation, we selected these proteins for further investigation. Inhibition of the Arp2/3 complex by CK666 prevented formation of model Hirano bodies. Since Arp2/3 activation occurs via the WASH or WAVE complex, we next investigated how these proteins affect Hirano body formation. Whereas model Hirano bodies could form in WASH-deficient cells, they failed to form in cells lacking HSPC300, a member of the WAVE complex. We identified other proteins required for Hirano body formation that include profilin and VASP, an actin nucleation factor. In the case of VASP, both its G- and F-actin binding domains were required for model Hirano body formation. Collectively, our results indicate that de novo actin polymerization is required to form model Hirano bodies.

  7. Myosin II does not contribute to wound repair in Dictyostelium cells

    Directory of Open Access Journals (Sweden)

    Shigehiko Yumura

    2014-09-01

    Full Text Available Cells are always subjected to mechanical stresses, resulting in wounds of the cell membrane, but cells are able to repair and reseal their wounded membrane. Previous reports have shown that actin and myosin II accumulate around the wound and that the constriction of this purse-string closes the membrane pore. Here, we developed a microsurgical wound assay to assess wound repair in Dictyostelium cells. Fluorescent dye that had been incorporated into the cells leaked out for only 2–3 sec after wounding, and a GFP-derived, fluorescent Ca2+ sensor showed that intracellular Ca2+ transiently increased immediately after wounding. In the absence of external Ca2+, the cell failed to repair itself. During the repair process, actin accumulated at the wounded sites but myosin II did not. The wounds were repaired even in myosin II null cells to a comparable degree as the wild-type cells, suggesting that myosin II does not contribute to wound repair. Thus, the actomyosin purse-string constriction model is not a common mechanism for wound repair in eukaryotic cells, and this discrepancy may arise from the difference in cell size.

  8. PKC-Mediated ZYG1 Phosphorylation Induces Fusion of Myoblasts as well as of Dictyostelium Cells

    Directory of Open Access Journals (Sweden)

    Aiko Amagai

    2012-01-01

    Full Text Available We have previously demonstrated that a novel protein ZYG1 induces sexual cell fusion (zygote formation of Dictyostelium cells. In the process of cell fusion, involvements of signal transduction pathways via Ca2+ and PKC (protein kinase C have been suggested because zygote formation is greatly enhanced by PKC activators. In fact, there are several deduced sites phosphorylated by PKC in ZYG1 protein. Thereupon, we designed the present work to examine whether or not ZYG1 is actually phosphorylated by PKC and localized at the regions of cell-cell contacts where cell fusion occurs. These were ascertained, suggesting that ZYG1 might be the target protein for PKC. A humanized version of zyg1 cDNA (mzyg1 was introduced into myoblasts to know if ZYG1 is also effective in cell fusion of myoblasts. Quite interestingly, enforced expression of ZYG1 in myoblasts was found to induce markedly their cell fusion, thus strongly suggesting the existence of a common signaling pathway for cell fusion beyond the difference of species.

  9. Dicty_cDB: [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ts) Value N U49650 |U49650.1 Dictyostelium discoideum calcium-dependent cell adhe...sion molecule-1 DdCAD-1 (cadA) mRNA, complete cds. 624 0.0 2 U20997 |U20997.1 Dictyostelium discoideum putat...ive 25 kDa protein mRNA, partial cds. 565 0.0 3 AF340153 |AF340153.1 Dictyostelium discoideum calcium-depend... U20997_1( U20997 |pid:none) Dictyostelium discoideum putative 25 k... 199 3e-50 ...AC116551_17( AC116551 |pid:none) Dictyostelium discoideum chromoso... 86 3e-16 AJ575138_1( AJ575138 |pid:non

  10. Dicty_cDB: [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available bits) Value N X03281 |X03281.1 Dictyostelium discoideum gene for actin A8. 1166 0....0 2 AC116957 |AC116957.2 Dictyostelium discoideum chromosome 2 map 1685067-2090751 strain AX4, complete seq...uence. 1112 0.0 4 M14146 |M14146.1 D.discoideum actin 15 gene, complete cds. 1043 0.0 2 AC115579 |AC115579.2 Dictyostelium di...equence. 1043 0.0 4 AC116986 |AC116986.2 Dictyostelium discoideum chromosome 2 map 2234041-2567370 strain AX...4, complete sequence. 969 0.0 5 U25660 |U25660.1 Dictyostelium discoideum actin gene, partial cds. 910 0.0 2 AC115577 |AC115577.2 Di

  11. Dicty_cDB: [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available icant alignments: (bits) Value N AC116957 |AC116957.2 Dictyostelium discoideum ch...romosome 2 map 1685067-2090751 strain AX4, complete sequence. 753 0.0 5 X03281 |X03281.1 Dictyostelium disco...ideum gene for actin A8. 640 0.0 2 AC116986 |AC116986.2 Dictyostelium discoideum chromosome 2 map 2234041-25...n 15 gene, complete cds. 618 0.0 3 AC115579 |AC115579.2 Dictyostelium discoideum chromosome 2 map 4915084-50...05461 strain AX4, complete sequence. 618 0.0 7 AC115577 |AC115577.2 Dictyostelium discoideum chromosome 2 ma

  12. Dicty_cDB: [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 1239 0.0 5 X03281 |X03281.1 Dictyostelium discoideum gene for actin A8. 1005 0.0 ...ce. 946 0.0 7 M14146 |M14146.1 D.discoideum actin 15 gene, complete cds. 928 0.0 3 AC115579 |AC115579.2 Dictyostelium di...ce. 928 0.0 5 U25660 |U25660.1 Dictyostelium discoideum actin gene, partial cds. 833 0.0 2 AC115577 |AC115577.2 Dictyostelium di...ctyostelium discoideum gene for actin A12. 743 0.0 2 AC116956 |AC116956.2 Dictyostelium disco...VF (Link to library) VFC230 (Link to dictyBase) - - - Contig-U16382-1 VFC230P (Link

  13. Dicty_cDB: [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available leracea genomic clone BOHVF14, DNA sequence. 30 0.61 3 AC116957 |AC116957.2 Dictyostelium di...ctyostelium discoideum chromosom... 93 2e-17 AC115612_2( AC115612 |pid:none) Dictyostelium di...S2) RecName: Full=FNIP repeat-containing protein DDB_G02906... 84 8e-15 U66528_1( U66528 |pid:none) Dictyostelium di...scoideum CigB (cigB) m... 83 2e-14 AC115604_12( AC115604 |pid:none) Dictyostelium di...scoideum chromoso... 82 2e-14 AC115680_16( AC115680 |pid:none) Dictyostelium discoideum chromoso.

  14. Identification of a target for CudA, the transcription factor which directs formation of the Dictyostelium tip organiser

    OpenAIRE

    WANG, HONG-YU; Williams, Jeffrey G.

    2010-01-01

    The tip of the Dictyostelium slug functions much like an embryonic organiser; when grafted onto the flank of a recipient slug, it recruits a mass of prespore cells and leads them away as part of a secondary slug. CudA is a nuclear protein which is expressed in prespore cells where it acts as a specific transcription factor. CudA is also expressed in an anteriorly located group of cells, the tip-organiser, that is believed to constitute the functional tip. We identify an expansin-like gene, ex...

  15. Ras Proteins Have Multiple Functions in Vegetative Cells of Dictyostelium

    Science.gov (United States)

    Bolourani, Parvin; Spiegelman, George; Weeks, Gerald

    2010-01-01

    During the aggregation of Dictyostelium cells, signaling through RasG is more important in regulating cyclic AMP (cAMP) chemotaxis, whereas signaling through RasC is more important in regulating the cAMP relay. However, RasC is capable of substituting for RasG for chemotaxis, since rasG− cells are only partially deficient in chemotaxis, whereas rasC−/rasG− cells are totally incapable of chemotaxis. In this study we have examined the possible functional overlap between RasG and RasC in vegetative cells by comparing the vegetative cell properties of rasG−, rasC−, and rasC−/rasG− cells. In addition, since RasD, a protein not normally found in vegetative cells, is expressed in vegetative rasG− and rasC−/rasG− cells and appears to partially compensate for the absence of RasG, we have also examined the possible functional overlap between RasG and RasD by comparing the properties of rasG− and rasC−/rasG− cells with those of the mutant cells expressing higher levels of RasD. The results of these two lines of investigation show that RasD is capable of totally substituting for RasG for cytokinesis and growth in suspension, whereas RasC is without effect. In contrast, for chemotaxis to folate, RasC is capable of partially substituting for RasG, but RasD is totally without effect. Finally, neither RasC nor RasD is able to substitute for the role that RasG plays in regulating actin distribution and random motility. These specificity studies therefore delineate three distinct and none-overlapping functions for RasG in vegetative cells. PMID:20833893

  16. Expression of an activated rasD gene changes cell fate decisions during Dictyostelium development.

    Science.gov (United States)

    Louis, S A; Spiegelman, G B; Weeks, G

    1997-02-01

    It has been previously demonstrated that the expression of an activated rasD gene in wild-type Dictyostelium cells results in formation of aggregates with multitips, instead of the normal single tips, and a block in further development. In an attempt to better understand the role of activated RasD development, we examined cell-type-specific gene expression in a strain stably expressing high levels of RasD[G12T]. We found that the expression of prestalk cell-specific genes ecmA and tagB was markedly enhanced, whereas the expression of the prespore cell-specific gene cotC was reduced to very low levels. When the fate of cells in the multitipped aggregate was monitored with an ecmA/lacZ fusion, it appeared that most of the cells eventually adopted prestalk gene expression characteristics. When mixtures of the [G12T]rasD cells and Ax3 cells were induced to differentiate, chimeric pseudoplasmodia were not formed. Thus, although the [G12T]rasD transformant had a marked propensity to form prestalk cells, it could not supply the prestalk cell population when mixed with wild-type cells. Both stalk and spore cell formation occurred in low cell density monolayers of the [G12T]rasD strain, suggesting that at least part of the inhibition of stalk and spore formation during multicellular development involved inhibitory cell interactions within the cell mass. Models for the possible role of rasD in development are discussed.

  17. Characterisation of a DNA sequence element that directs Dictyostelium stalk cell-specific gene expression.

    Science.gov (United States)

    Ceccarelli, A; Zhukovskaya, N; Kawata, T; Bozzaro, S; Williams, J

    2000-12-01

    The ecmB gene of Dictyostelium is expressed at culmination both in the prestalk cells that enter the stalk tube and in ancillary stalk cell structures such as the basal disc. Stalk tube-specific expression is regulated by sequence elements within the cap-site proximal part of the promoter, the stalk tube (ST) promoter region. Dd-STATa, a member of the STAT transcription factor family, binds to elements present in the ST promoter-region and represses transcription prior to entry into the stalk tube. We have characterised an activatory DNA sequence element, that lies distal to the repressor elements and that is both necessary and sufficient for expression within the stalk tube. We have mapped this activator to a 28 nucleotide region (the 28-mer) within which we have identified a GA-containing sequence element that is required for efficient gene transcription. The Dd-STATa protein binds to the 28-mer in an in vitro binding assay, and binding is dependent upon the GA-containing sequence. However, the ecmB gene is expressed in a Dd-STATa null mutant, therefore Dd-STATa cannot be responsible for activating the 28-mer in vivo. Instead, we identified a distinct 28-mer binding activity in nuclear extracts from the Dd-STATa null mutant, the activity of this GA binding activity being largely masked in wild type extracts by the high affinity binding of the Dd-STATa protein. We suggest, that in addition to the long range repression exerted by binding to the two known repressor sites, Dd-STATa inhibits transcription by direct competition with this putative activator for binding to the GA sequence.

  18. GBF-dependent family genes morphologically suppress the partially active Dictyostelium STATa strain.

    Science.gov (United States)

    Shimada, Nao; Kanno-Tanabe, Naoko; Minemura, Kakeru; Kawata, Takefumi

    2008-02-01

    Transcription factor Dd-STATa, a functional Dictyostelium homologue of metazoan signal transducers and activators of transcription proteins, is necessary for culmination during development. We have isolated more than 18 putative multicopy suppressors of Dd-STATa using genetic screening. One was hssA gene, whose expression is known to be G-box-binding-factor-dependent and which was specific to prestalk A (pstA) cells, where Dd-STATa is activated. Also, hssA mRNA was expressed in pstA cells in the Dd-STATa-null mutant. At least 40 hssA-related genes are present in the genome and constitute a multigene family. The tagged HssA protein was translated; hssA encodes an unusually high-glycine-serine-rich small protein (8.37 kDa), which has strong homology to previously reported cyclic-adenosine-monophosphate-inducible 2C and 7E proteins. Overexpression of hssA mRNA as well as frame-shifted versions of hssA RNA suppressed the phenotype of the partially active Dd-STATa strain, suggesting that translation is not necessary for suppression. Although overexpression of prespore-specific genes among the family did not suppress the parental phenotype, prestalk-specific family members did. Although overexpression of the hssA did not revert the expression of Dd-STATa target genes, and although its suppression mechanism remains unknown, morphological reversion implies functional relationships between Dd-STATa and hssA.

  19. Dicty_cDB: [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ing significant alignments: (bits) Value N AC117176 |AC117176.2 Dictyostelium discoideum chromosome 2 map 50...18074-5200947 strain AX4, complete sequence. 34 6e-07 16 AC116977 |AC116977.2 Dictyostelium di...um perfringens DNA, complete genome, section 7/10. 36 0.002 11 AC115598 |AC115598.2 Dictyostelium di...hromosome 8, clone RP11-378J9, complete sequence. 36 0.009 6 AC116957 |AC116957.2 Dictyostelium discoideum c... (atpD) gene, partial cds. 34 0.016 4 AC116956 |AC116956.2 Dictyostelium discoide

  20. A retinoblastoma orthologue is a major regulator of S-phase, mitotic, and developmental gene expression in Dictyostelium.

    Directory of Open Access Journals (Sweden)

    Kimchi Strasser

    Full Text Available BACKGROUND: The retinoblastoma tumour suppressor, Rb, has two major functions. First, it represses genes whose products are required for S-phase entry and progression thus stabilizing cells in G1. Second, Rb interacts with factors that induce cell-cycle exit and terminal differentiation. Dictyostelium lacks a G1 phase in its cell cycle but it has a retinoblastoma orthologue, rblA. METHODOLOGY/PRINCIPAL FINDINGS: Using microarray analysis and mRNA-Seq transcriptional profiling, we show that RblA strongly represses genes whose products are involved in S phase and mitosis. Both S-phase and mitotic genes are upregulated at a single point in late G2 and again in mid-development, near the time when cell cycling is reactivated. RblA also activates a set of genes unique to slime moulds that function in terminal differentiation. CONCLUSIONS: Like its mammalian counterpart Dictyostelium, RblA plays a dual role, regulating cell-cycle progression and transcriptional events leading to terminal differentiation. In the absence of a G1 phase, however, RblA functions in late G2 controlling the expression of both S-phase and mitotic genes.