Wild
            Dictyostelium discoideum
            social amoebae show plastic responses to the presence of nonrelatives during multicellular development

While the role of myosin II in muscle contraction has been well characterized, less is known about the role of myosin II in non-muscle cells. Recent molecular genetic experiments on Dictyostelium discoideum show that myosin II is necessary for cytokinesis and multicellular development. Here we use immunofluorescence microscopy with monoclonal and polyclonal antimyosin antibodies to visualize myosin II in cells of the multicellular D. discoideum slug. A subpopulation of peripheral and anterior cells label brightly with antimyosin II antibodies, and many of these cells display a polarized intracellular distribution of myosin II. Other cells in the slug label less brightly and their cytoplasm displays a more homogeneous distribution of myosin II. These results provide insight into cell motility within a three-dimensional tissue and they are discussed in relation to the possible roles of myosin II in multicellular development.

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CbfA, the C-Module DNA-Binding Factor, Plays an Essential Role in the Initiation of Dictyostelium discoideum Development

Eukaryotic Cell ◽

10.1128/ec.3.5.1349-1358.2004 ◽

2004 ◽

Vol 3 (5) ◽

pp. 1349-1358 ◽

Cited By ~ 11

Author(s):

Thomas Winckler ◽

Negin Iranfar ◽

Peter Beck ◽

Ingo Jennes ◽

Oliver Siol ◽

...

Keyword(s):

Dna Binding ◽

Cell Density ◽

Dictyostelium Discoideum ◽

Ectopic Expression ◽

Development Program ◽

Cell Physiology ◽

Dependent Manner ◽

Wild Type ◽

Gene Encoding ◽

Multicellular Development

ABSTRACT We recently isolated from Dictyostelium discoideum cells a DNA-binding protein, CbfA, that interacts in vitro with a regulatory element in retrotransposon TRE5-A. We have generated a mutant strain that expresses CbfA at <5% of the wild-type level to characterize the consequences for D. discoideum cell physiology. We found that the multicellular development program leading to fruiting body formation is highly compromised in the mutant. The cells cannot aggregate and stay as a monolayer almost indefinitely. The cells respond properly to prestarvation conditions by expressing discoidin in a cell density-dependent manner. A genomewide microarray-assisted expression analysis combined with Northern blot analyses revealed a failure of CbfA-depleted cells to induce the gene encoding aggregation-specific adenylyl cyclase ACA and other genes required for cyclic AMP (cAMP) signal relay, which is necessary for aggregation and subsequent multicellular development. However, the cbfA mutant aggregated efficiently when mixed with as few as 5% wild-type cells. Moreover, pulsing cbfA mutant cells developing in suspension with nanomolar levels of cAMP resulted in induction of acaA and other early developmental genes. Although the response was less efficient and slower than in wild-type cells, it showed that cells depleted of CbfA are able to initiate development if given exogenous cAMP signals. Ectopic expression of the gene encoding the catalytic subunit of protein kinase A restored multicellular development of the mutant. We conclude that sensing of cell density and starvation are independent of CbfA, whereas CbfA is essential for the pattern of gene expression which establishes the genetic network leading to aggregation and multicellular development of D. discoideum.

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Various dictyostelids from the environment can produce multilamellar bodies

Canadian Journal of Microbiology ◽

10.1139/cjm-2020-0187 ◽

2020 ◽

Vol 66 (12) ◽

pp. 679-688

Author(s):

Alicia F. Durocher ◽

Cynthia Gagné-Thivierge ◽

Steve J. Charette

Keyword(s):

Cell Communication ◽

Laboratory Strain ◽

Food Storage ◽

Epifluorescence Microscopy ◽

Free Living ◽

Multicellular Development ◽

Multilamellar Bodies ◽

Transmission Electron ◽

Axenic Conditions ◽

Social Amoebae

Multilamellar bodies (MLBs), structures composed of concentric membrane layers, are known to be produced by different protozoa, including species of ciliates, free-living amoebae, and Dictyostelium discoideum social amoebae. Initially believed to be metabolic waste, potential roles like cell communication and food storage have been suggested for D. discoideum MLBs, which could be useful for the multicellular development of social amoebae and as a food source. However, among dictyostelids, this phenomenon has only been observed with D. discoideum, and mainly with laboratory strains grown in axenic conditions. It was thought that other social amoebae may also produce MLBs. Four environmental social amoeba isolates were characterized. All strains belong to the Dictyostelium genus, including some likely to be Dictyostelium giganteum. They have distinctive phenotypes comprising their growth rate on Klebsiella aerogenes lawns and the morphology of their fruiting bodies. They all produce MLBs like those produced by a D. discoideum laboratory strain when grown on K. aerogenes lawns, as revealed by analysis using the H36 antibody in epifluorescence microscopy as well as by transmission electron microscopy. Consequently, this study shows that MLBs are produced by various dictyostelid species, which further supports a role for MLBs in the lifestyle of amoebae.

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Comparative genomics of the social amoebae Dictyostelium discoideum and Dictyostelium purpureum

Genome Biology ◽

10.1186/gb-2011-12-2-r20 ◽

2011 ◽

Vol 12 (2) ◽

pp. R20 ◽

Cited By ~ 97

Author(s):

Richard Sucgang ◽

Alan Kuo ◽

Xiangjun Tian ◽

William Salerno ◽

Anup Parikh ◽

...

Keyword(s):

Comparative Genomics ◽

Dictyostelium Discoideum ◽

The Social ◽

Dictyostelium Purpureum ◽

Social Amoebae

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ForC, a novel type of formin family protein lacking an FH1 domain, is involved in multicellular development in Dictyostelium discoideum

Journal of Cell Science ◽

10.1242/jcs.00265 ◽

2003 ◽

Vol 116 (4) ◽

pp. 711-723 ◽

Cited By ~ 24

Author(s):

C. Kitayama

Keyword(s):

Dictyostelium Discoideum ◽

Multicellular Development ◽

Family Protein

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Exposure to dense bacteria lawns does not cause the social amoeba Dictyostelium discoideum to carry bacteria through the social stage

10.7287/peerj.preprints.2698v1 ◽

2017 ◽

Author(s):

Debra A Brock ◽

Alicia Canas ◽

Kai Jones ◽

David C Queller ◽

Joan E Strassmann

Keyword(s):

Dictyostelium Discoideum ◽

Associated Bacteria ◽

Social Amoeba ◽

Future Studies ◽

Bacterial Cultures ◽

Large Numbers ◽

The Social ◽

External Forces ◽

Social Amoebae ◽

Food Bacteria

Background. Interactions between eukaryotic amoebae and bacteria are understudied and important. Bacteria inside of amoebae are protected from external forces including antibiotics. An excellent model for bacteria-amoeba interactions is the social amoeba Dictyostelium discoideum and its associated bacteria. A third of wild-collected clones of the soil-dwelling amoeba Dictyostelium discoideum exhibit a suite of characteristics that make them simple farmers of bacteria. They carry bacteria internally through the social spore-making stage. They then release these bacteria to grow and subsequently eat them, prudently stopping before they are entirely consumed so some bacteria can be carried to the next generation. D. discoideum defend their food bacteria with other inedible bacteria that produce compounds toxic to non-farmers. Both carried bacteria and social amoeba hosts have demonstrated co-evolved characteristics. Most farmer clones discovered to date carry inedible Burkholderia in addition to food bacteria, but it is not clear whether or not a preponderance of naïve bacteria might induce the farming state by overwhelming the phagocytic actions of the host amoebae. In this study we address this question with D. discoideum clones that naturally carry bacteria and those that do not. Will naïve bacteria in large numbers succeed in colonizing the amoebae? Methods. We grew five non-farmer clones and five farmer clones of wild-collected Dictyostelium discoideum on three different concentrations of a highly palatable bacterial food source, Klebsiella pneumoniae. We then tested them to see if they carried bacteria through the social stage. Results. We found that bacterial density did not have a significant effect on whether or not the clones carried bacteria through the social stage. Even those grown in very dense bacterial cultures were able to shed them successfully unless they were also carrying Burkholderia. Discussion. Our results indicate that even a preponderance of food bacteria cannot overwhelm the ability of social amoebae to digest and not carry bacteria. Apparently, only the inedible Burkholderia have that effect. This points to the importance of understanding co-infection with multiple bacteria because those that cannot induce carriage can nevertheless become carried, foiling digestive processes, but only in the presence of another bacterium. Future studies of host bacteria interactions should consider using multiple bacteria simultaneously.

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Mitochondrial regulation in Dictyostelium discoideum

10.7287/peerj.preprints.26930 ◽

2018 ◽

Author(s):

Mehak Rafiq

Keyword(s):

Dictyostelium Discoideum ◽

Serine Proteases ◽

Model Organism ◽

Complex Life Cycle ◽

Transcriptional Networks ◽

Multicellular Development ◽

Mitochondrial Regulation ◽

Rhomboid Proteases ◽

The Social ◽

Membrane Bound

Proteolysis is increasingly documented as a method of regulation of mitochondrial function. Our studies of rhomboidfamily proteins’ roles in organelles show that this is also the case in the social amoeba Dictyostelium discoideum, in which four of these membrane-bound, evolutionarily ubiquitous, serine proteases are found. Rhomboid proteases act on disparate substrates in different organisms so far studied, but their mode of action is conserved: their location in the membrane means that their membrane-tethered substrates can act in signalling upon release, or be activated, by rhomboid-mediated cleavage. Among eukaryotic rhomboids is the mitochondrial protease ‘PARL’, which ensures the maintenance of the structural and functional integrity of mitochondria and plastids, but we have found that other Dictyostelium rhomboids also affect the organelle. Studying the development and behaviour of Dictyostelium, a microbial model organism with a complex life cycle that includes uni- and multicellular stages, allowed investigation of the role of rhomboids in unicellular vegetative growth, multicellular development and sporulation, phagocytosis, and response to the environment. We found that two rhomboid-null mutants gave rise to changes in development, rhmA altering the response to chemoattractants and demonstrating decreased motility in general, whereas rhmB null cells had slower growth rates with decreased response to folic acid. RhmA, although located in the contractile vacuole, affects the ultrastructure of mitochondria, and RhmB-GFP fusions protein was localised to the mitochondrion. qPCR analysis revealed RhmA and RhmB transcript levels peaking during the multicellular growth phase and transcriptional networks suggest the Dictyostelium rhmA is regulated along with the orthologues of Saccharomyces cerevisiae mitochondrial rhomboid substrates.

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Terpene synthase genes in eukaryotes beyond plants and fungi: Occurrence in social amoebae

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1610379113 ◽

2016 ◽

Vol 113 (43) ◽

pp. 12132-12137 ◽

Cited By ~ 47

Author(s):

Xinlu Chen ◽

Tobias G. Köllner ◽

Qidong Jia ◽

Ayla Norris ◽

Balaji Santhanam ◽

...

Keyword(s):

Early Stage ◽

Terpene Synthase ◽

Functional Study ◽

Terpene Biosynthesis ◽

Terpene Synthases ◽

Multicellular Development ◽

Stage Of Development ◽

The Social ◽

Volatile Terpenes ◽

Social Amoebae

Terpenes are structurally diverse natural products involved in many ecological interactions. The pivotal enzymes for terpene biosynthesis, terpene synthases (TPSs), had been described only in plants and fungi in the eukaryotic domain. In this report, we systematically analyzed the genome sequences of a broad range of nonplant/nonfungus eukaryotes and identified putative TPS genes in six species of amoebae, five of which are multicellular social amoebae from the order of Dictyosteliida. A phylogenetic analysis revealed that amoebal TPSs are evolutionarily more closely related to fungal TPSs than to bacterial TPSs. The social amoeba Dictyostelium discoideum was selected for functional study of the identified TPSs. D. discoideum grows as a unicellular organism when food is abundant and switches from vegetative growth to multicellular development upon starvation. We found that expression of most D. discoideum TPS genes was induced during development. Upon heterologous expression, all nine TPSs from D. discoideum showed sesquiterpene synthase activities. Some also exhibited monoterpene and/or diterpene synthase activities. Direct measurement of volatile terpenes in cultures of D. discoideum revealed essentially no emission at an early stage of development. In contrast, a bouquet of terpenes, dominated by sesquiterpenes including β-barbatene and (E,E)-α-farnesene, was detected at the middle and late stages of development, suggesting a development-specific function of volatile terpenes in D. discoideum. The patchy distribution of TPS genes in the eukaryotic domain and the evidence for TPS function in D. discoideum indicate that the TPS genes mediate lineage-specific adaptations.

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