Protein Synthesis Initiated by Cell Fusion in <i>Dictyostelium discoideum</i>

Moriyama, Ryoichi; Yanagisawa, Keiji

doi:10.1111/j.1440-169x.1988.00169.x

Cited by 3 publications

(2 citation statements)

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“…autoinhibitor, CFIF) to regulate other events of macrocyst formation. In an effort to identify proteins involved in ZGC differentiation, protein synthesis was assessed in zygotes produced both by mixed‐mating cultures and the synchronous (delayed‐mixed‐mating) development system (Moriyama & Yanagisawa, 1987; Saga & Yanagisawa, 1982). [ 35 S]‐methionine pulse‐labelled protein profiles were then resolved by two‐dimensional gel electrophoresis.…”

Section: Heterothallic Sexual Development Of Dictyostelium Discoimentioning

confidence: 99%

Signalling and sex in the social amoebozoans

O’Day

Keszei

2011

Biological Reviews

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The social amoebozoans have a life tricycle consisting of asexual multicellular development leading to fruiting bodies, sexual multicellular development resulting in macrocysts, and unicellular development generating microcysts. This review covers the events of sexual development in the best-studied heterothallic (Dictyostelium discoideum) and homothallic (D. mucoroides) mating systems. Sexual development begins with pheromonal interactions that produce fusion-competent cells (gametes) which undergo cell and pronuclear fusion. Calcium- and calmodulin-mediated signalling mediates these early events. As they initiate chemotactic signalling, each zygote increases in size becoming a zygote giant cell. Using cyclic AMP (cAMP), the zygote chemotactically lures in amoebae and engulfs them in an act of cannibalistic phagocytosis. Chemotaxis proceeds more quickly than endocytosis because the breakdown products of cAMP (5-AMP, adenosine) bind to a presumptive adenosine receptor to inhibit sexual phagocytosis. This slowing of phagocytosis allows amoebae to accumulate around the zygote to form a precyst aggregate. Zygote giant cells also produce several other signalling molecules that feed back to regulate early events. The amoebae surrounding the zygote seal their fate as zygotic foodstuff by secreting a primary cellulose wall, the extracellular sheath, around the zygote and aggregated amoebae, which prevents their escape. Phagocytosis within this precyst continues until all peripheral amoebae are internalized as endocytes and the final macrocyst wall is formed. Endocyte digestion results in a mature macrocyst with a uniform cytoplasm containing a diploid nucleus. After detailing the morphological events of heterothallic and homothallic mating, we review the various intercellular signalling events and other mechanisms involved in each stage. This complete and comprehensive review sets the stage for future research on the unique events that characterize sex in the social amoebozoans.

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Section: Heterothallic Sexual Development Of Dictyostelium Discoimentioning

confidence: 99%

Signalling and sex in the social amoebozoans

O’Day

Keszei

2011

Biological Reviews

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“…In the unicellular organism, Chlamydomonas reinhardtii, expression of a zygote specific gene is reported but its product is used to attack chloroplast DNA of one parent (Armbrust et al 1993 ATAATAATAATAATAATAATAATAATAATAATAATAACAATAATAATAGTAATAATAATAATAATAATAATAACAGT~T~T~T~TA 720 141N N N N N N N N N N N N N N N N S N N N N N N N N S N N N N AT~T~TTAACAAT~T~T~T~T~T~T~T~A~T~T~T~T~A~T~T~TTTTASI0 171 N N N I N N N N N N N N N N N N N N N I N N 95 accumulation of mRNAs, cellular maturation to the sexually competent state may include transcription of genes necessary for the post-fusion development. In our previous studies, notable alterations of the protein profiles after cell fusion were observed (Moriyama and Yanagisawa 1987). Detection of fewer alterations in the mRNA profiles revealed in this study may suggest that the translational control of gene expression governs early sexual development in D.…”

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Expression of starvation-induced genes in zygotes ofDictyostelium discoideum

et al. 1998

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Two cDNA fragments induced in developing zygotes of Dictyostelium discoideum were isolated by mRNA differential display. The relevant genes were also found to be expressed during asexual development, suggesting that sexual and asexual development share common molecular mechanisms in D. discoideum. Key wordr Developmental genes~ Dictyostelium disco/deum~mRNA differential display~Zygote developmentDictyostelium discoideum proliferates as a unicellular ameba, but upon starvation the cells gather and form multicellular structures known as fruiting bodies. Alternatively, they sexually fuse to form zygotic giant cells, which engulf surrounding cells and eventually develop into macrocysts (Nickerson and Raper 1973, O'Day 1979). Simplicity of the sexual development, fidelity of molecular biological techniques, and establishment of synchronous cell fusion system show that it may serve as a useful experimental system for cell recognition, membrane fusion, and zygote development.Molecular analyses of sexual cell fusion in D. discoideum have been performed to a limited extent (Urushihara 1997), but that for zygote development it is very scarce. In the present study we analyzed the pattern of gene expression during zygote development using the mRNA differential display method, and found that two novel genes are induced shortly after cell fusion.Complementary heterothallic strains of D. discoideum, NC4 and HM1, were used. Zygote giant cells were obtained by co-incubating sexually mature cells of NC4 and HM1 on a rotary shaker at 120 rpm for 30 min at 22 C as described previously (Saga eta/. 1983). Where necessary, giant cells thus obtained (crude GCs) were freed of unfused cells by differential centrifugation to yield purified GCs. Both crude and purified GCs developed into macrocysts after a 48 hr incubation on nitrocellulose membrane filters layered on wet support pads.The necessity of de novo mRNA synthesis for macrocyst formation was determined using actinomycin D, an inhibitor Present address: Doi Bioassymmetry Project, ERATO, JST, Tsukuba Research Consortium, Tsukuba, Ibaraki, 300-26 Japan of RNA polymerasell. The presence of 125/zg/ml of actinomycin D for 3 hr of the initial development suppressed macrocyst development (data not shown), suggesting that the expression of new genes occurs during this period induced by cell fusion.Messenger RNA differential display (mRNAdd) was performed by a standard protocol (Liang et a/. 1993) using RNA map kit (GeneHunter; Brooklyn, MA. USA) for total RNA prepared from the cells at 0, 3, and 6 hr of sexual development.From roughly 3,000 cDNA fragments amplified by combinations of 3 anchored oligo (dT) and 20 arbitrary primers, two fragments, designated as G9b and A5, were reproducibly found to be present in the samples of 3 and 6 hr of development but absent in that of 0 hr (Fig. la). These fragments were then extracted from the electrophoresis gel, radiolabeled, and used as probes for northern hybridization to detect expression of the relevant genes (G9b and A5, respectively). They we...

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A Maltose-binding-protein-like Peptide Accumulates after Mixing Two Types of Sexually Competent Cells of a Cellular Slime Mold, Dictyostelium discoideum.

et al. 1995

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A cellular slime mold, Dictyostelium discoideum is an ideal model organism for examining sexual differentiation and mating. Cells on agar plates can obtain sexual competence syn chronously by culturing in liquid medium including food bacteria with shaking. After removing the bacteria, mixing opposite mating type cells of D. discoideum results in beginning of mating. They fuse with each other, forming multinucleate cells. After giant cells are formed, they attract and engulf smaller cells. Giant cells develop into macrocysts. Macrocysts undergo meiosis and at the end of dormancy, their progeny amoebae are released. Though formation of multinuclear cells is unique, serial sexual events such as plasmogany, karyogamy, formation of thick wall, and meiosis are universal in the mating of isogamous organisms. Involvement of Ca2+, cAMP with mating is also the case in fertilizing green algae (Goodenough and Thoner 1983). Analysis of mating mechanism using Dictyostelium cell will reveal common mechanism among various organisms.Dictyostelium discoideum is one of the organisms that glycoproteins at mating are precisely studied as well as sea urchin (Gilbert 1988) 1987 , Ishikawa et al. 1991. These results suggest that sugars play important roles in the gamete differentiation and fusion of mating cells. But there have been a few immunological researches on sugar binding proteins of D. dis coideum, while many papers reported precisely roles of carbohydrates on cell membrane. In bacteria, maltose translocator upon cell membrane is a recognition target for infecting phage lambda (Randall-Hazelbauer and Schwartz 1973), and in human macrophages, mannose receptor mediates phagocytosis of saccharide-coated particles (Warr 1980).We have tried to detect maltose-binding protein in the cell of D. discoideum after beginning of mating using antibody to bacterial maltose-binding protein (MBP).This paper reports accumulation of two MBP-like peptides 24hr after mixing two types of sexually competent cells for the first time. We show morphology of mating cells in DAPI-fluorescence microscopy. We discuss about the nature of isoforms of MBP-like protein, and speculate their potential roles in

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Protein Synthesis Initiated by Cell Fusion in Dictyostelium discoideum

Cited by 3 publications

References 24 publications

Signalling and sex in the social amoebozoans

Signalling and sex in the social amoebozoans

Expression of starvation-induced genes in zygotes ofDictyostelium discoideum

A Maltose-binding-protein-like Peptide Accumulates after Mixing Two Types of Sexually Competent Cells of a Cellular Slime Mold, Dictyostelium discoideum.

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