scholarly journals Stalk cell formation in monolayers from isolated prestalk and prespore cells of Dictyostelium discoideum: evidence for two populations of prestalk cells

Development ◽  
1988 ◽  
Vol 104 (1) ◽  
pp. 121-127 ◽  
Author(s):  
L. Kwong ◽  
A. Sobolewski ◽  
L. Atkinson ◽  
G. Weeks
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Cell Population ◽  
Cell Formation ◽  
Cell Types ◽  
Stalk Cell ◽  
Cell Populations ◽  
Anterior Portion ◽  
Percoll Gradients ◽  
Two Populations

Cells from the pseudoplasmodial stage of Dictyostelium discoideum differentiation were dispersed and separated on Percoll gradients into prestalk and prespore cells. The requirements for stalk cell formation in low-density monolayers from the two cell types were determined. The isolated prespore cells required both the Differentiation Inducing Factor (DIF) and cyclic AMP for stalk cell formation. In contrast, only part of the isolated prestalk cell population required both cyclic AMP and DIF, the remainder requiring DIF alone, suggesting the possibility that there were two populations of prestalk cells, one independent of cyclic AMP and one dependent on cyclic AMP for stalk cell formation. The finding that part of the prestalk cell population required only a brief incubation in the presence of DIF to induce stalk cell formation, whilst the remainder required a considerably longer incubation in the presence of both DIF and cyclic AMP was consistent with this idea. In addition, stalk cell formation from cyclic-AMP-dependent prestalk cells was relatively more sensitive to caffeine inhibition than stalk cell formation from cyclic-AMP-independent prestalk cells. The latter cells were enriched in the most anterior portion of the migrating pseudoplasmodium, indicating that there is spatial segregation of the two prestalk cell populations. The conversion of prespore cells to stalk cells took longer and was more sensitive to caffeine when compared to stalk cell formation from cyclic-AMP-dependent prestalk cells.

Stalk cell differentiation by cells from migrating slugs of Dictyostelium discoideum: special properties of tip cells

Development ◽  
1977 ◽  
Vol 42 (1) ◽  
pp. 105-113
Author(s):  
C. D. Town ◽  
E. Stanford
Keyword(s):  
Cell Differentiation ◽  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Active Substance ◽  
High Efficiency ◽  
Stalk Cell ◽  
Cell Populations ◽  
Distinct Cell ◽  
Tip Cells

When fragments of migrating slugs of D. discoideum are disaggregated and spread on agar containing 1 MM cyclic AMP, cells from all parts of the slug form stalk cells with high efficiency. When cyclic AMP is not added to the agar, normal fruiting of dissociated slug cells can be prevented by overlaying them with cellophane. Under these conditions only cells from the anterior 10% of the slug (the ‘tip’) give rise to appreciable numbers of stalk cells, all other cells remaining amoeboid. By separating distinct cell populations with cellophane we have shown that tip cells can induce cells from other parts of the slug to differentiate into stalk cells. The ability of tips to induce stalk cells is independent of tip age, but the proportion of cells induced depends both on the age of the slug and the part of the slug from which they are derived. The proportion induced is greater in older slugs than in newly formed ones, and in the older slugs is greater in the cells from fronts than from backs. The active substance released by the tip cells may be cyclic AMP.

Ammonia depletion and DIF trigger stalk cell intact Dictyostelium discoideum slugs

Development ◽  
1989 ◽  
Vol 105 (3) ◽  
pp. 569-574 ◽  
Author(s):  
M. Wang ◽  
P. Schaap
Keyword(s):  
Cell Differentiation ◽  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Stalk Cell

The differentiation-inducing factor, DIF, was induce stalk cell differentiation in Dictyostelium incubated as submerged monolayers. We investigated the regulates the differentiation of stalk cells in the was found that in migrating or submerged slugs DIF cell differentiation, which is most likely due to the antagonist. Cyclic AMP and ammonia were earlier antagonists in vitro. We show here that ammonia, but an antagonist for DIF-induced stalk cell can induce stalk cell differentiation when ammonia are enzymically depleted. However, depletion of cAMP increase the efficacy of DIF. We propose that the cell differentiation during early culmination may be drop in ammonia levels inside the organism.

The effect of ammonia on stalk cell formation in submerged monolayers of Dictyostelium discoideum

1983 ◽  
Vol 13 (4) ◽  
pp. 301-307 ◽  
Author(s):  
Nancy Neave ◽  
André Sobolewski ◽  
Gerald Weeks
Keyword(s):  
Dictyostelium Discoideum ◽  
Cell Formation ◽  
Stalk Cell

Regulation of stalk and spore antigen expression in monolayer cultures of Dictyostelium discoideum by pH

Development ◽  
1986 ◽  
Vol 96 (1) ◽  
pp. 131-150
Author(s):  
Janice A. Dominov ◽  
Christopher D. Town
Keyword(s):  
Dictyostelium Discoideum ◽  
Phenotypic Expression ◽  
Cell Formation ◽  
Antigen Expression ◽  
Low Ph ◽  
Stalk Cell ◽  
Protein Antigens ◽  
High Ph ◽  
Monolayer Cultures ◽  
Effects Of Ph

The terminal differentiation of Dictyostelium discoideum cells plated as monolayers with cyclic AMP is dramatically affected by developmental buffer conditions. High pH and addition of weak bases induces spore differentiation while low pH and weak acids favour stalk cell formation. In order to analyse the timing and nature of this regulation we have raised and characterized an anti-stalk serum which we have used together with an anti-spore serum to monitor developmental progression in the monolayer system and to detect the phenotypic effects of pH at earlier stages of development. The stalk serum detects both polysaccharide and protein antigens expressed during the terminal stages of normal development. In monolayer culture, the stalk-specific protein antigen appears precociously, while the timing of prespore vacuole appearance is unaffected. Expression of stalk polysaccharide antigens in monolayer cultures occurs as early as 12 h and is localized in a single subset of cells or region of extracellular space within the small cell clumps that form. The effects of pH (and acid/base) on these phenotype-specific antigens can be detected early in development, shortly after their first appearance. In monolayers of wild-type V12 M2 cells, the low pH regimes appear to act more by suppressing the spore than enhancing the stalk pathway, while the high pH regimes both suppress stalk and enhance spore antigen expression. In monolayers of the sporogenous mutant HM29, low pH regimes both enhance stalk antigen and suppress spore antigen expression. These results show that extracellular pH regulates phenotypic expression during a large part of the differentiation process and is not simply restricted to terminal cytodifferentiation.

scholarly journals Characterization of the Roco Protein Family in Dictyostelium discoideum

2010 ◽  
Vol 9 (5) ◽  
pp. 751-761 ◽  
Author(s):  
Wouter N. van Egmond ◽  
Peter J. M. van Haastert
Keyword(s):  
Dictyostelium Discoideum ◽  
Cell Formation ◽  
Slime Mold ◽  
Stalk Cell ◽  
Cellular Slime Mold ◽  
Developmental Defects ◽  
Content Type ◽  
Ras Gtpases ◽  
Cellular Slime

ABSTRACT The Roco family consists of multidomain Ras-GTPases that include LRRK2, a protein mutated in familial Parkinson's disease. The genome of the cellular slime mold Dictyostelium discoideum encodes 11 Roco proteins. To study the functions of these proteins, we systematically knocked out the roco genes. Previously described functions for GbpC, Pats1, and QkgA (Roco1 to Roco3) were confirmed, while novel developmental defects were identified in roco4- and roco11-null cells. Cells lacking Roco11 form larger fruiting bodies than wild-type cells, while roco4-null cells show strong developmental defects during the transition from mound to fruiting body; prestalk cells produce reduced levels of cellulose, leading to unstable stalks that are unable to properly lift the spore head. Detailed phylogenetic analysis of four slime mold species reveals that QkgA and Roco11 evolved relatively late by duplication of an ancestor roco4 gene (later than ∼300 million years ago), contrary to the situation with other roco genes, which were already present before the split of the common ancestor of D. discoideum and Polysphondylium pallidum (before ∼600 million years ago). Together, our data show that the Dictyostelium Roco proteins serve a surprisingly diverse set of functions and highlight Roco4 as a key protein for proper stalk cell formation.

Dictyostelium amoebae can differentiate into spores without cell-to-cell contact

Development ◽  
1981 ◽  
Vol 62 (1) ◽  
pp. 369-378
Author(s):  
Robert R. Kay ◽  
David J. Trevan
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Time Lapse ◽  
Cell Types ◽  
Spore Formation ◽  
Cellular Interaction ◽  
Cell Contact ◽  
Direct Cell ◽  
Petri Dishes ◽  
Intermediate Density

Amoebae of sporogenous mutants of Dictyostelium discoideum can differentiate into stalk cells and spores in the absence of normal morphogenesis when spread on agar containing cyclic-AMP. The efficiency of differentiation is improved when the amoebae are incubated as submerged monolayers in plastic petri dishes. Under these conditions spore formation is density dependent and hence requires some form of cellular interaction. To determine whether this interaction involves direct cell—cell contact we have made time-lapse films of cells differentiating at intermediate density. These films show that amoebae can develop into spores without making contact with any other cells. In addition, although some cells do divide during incubation, division is not necessary for spore formation. At higher densities small aggregates form which give rise to mixtures of stalk cells and spores. There is no detectable patterning of the two cell types within such aggregates.

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