Evidence for the formation of cell aggregates by chemotaxis in the development of the slime mold Dictyostelium discoideum

Bonner, John Tyler; Savage, Linda

doi:10.1002/jez.1401060102

Cited by 812 publications

(321 citation statements)

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“…Isolated prespore cells were washed twice and resuspended in Ca2+-free Bonner's salt solution (10 mM NaCl and 10 mM KCI) (1). Slugs were disaggregated by repeated centrifugations (2 or 3 times) at 2000 rpm for 2 min in ice-cold 5 mM MES (pH 7.0) containing 20mM EDTA.…”

Section: Lsolation Of Prespore Cellsmentioning

confidence: 99%

Efficient Induction of Sporulation of Dictyostelium Prespore Cells by 8‐Bromocyclic AMP under Both Submerged‐ and Shaken‐Culture Conditions and Involvement of Protein Kinase(s) in Its Action

Maeda

1992

Dev Growth Differ

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It is important to establish an experimental system in which sporulation of Dictyostelium can be induced at high cell densities to obtain sufficient amounts of materials for analysis of the molecular events leading to sporulation. 8-Bromo cAMP (Br-CAMP) was found to be effective for inducing sporulation by prespore cells of Dictyostelium discoideum NC4 at high cell densities under both submerged-and shaken-culture conditions. Ultrastructural studies revealed that the morphological changes associated with this sporulation proceeded normally in vitro. The effect of Br-CAMP was inhibited by two protein kinase inhibitors, K252a and staurosporine. Protein-phosphorylation experiments showed that Er-CAMP induced increased phosphorylations of a 96 kDa spore coat protein (SP96) and a protein with a mobility corresponding to a molecular weight of 50 kDa (p50-4). The protein kinase inhibitor K252a blocked the phosphorylations of both proteins. These proteins may be targets of particular protein kinase(s) that is activated by Br-CAMP. These findings indicate that the present experimental system should be useful for elucidating the molecular events involved in normal sporulation and the mechanism by which Br-CAMP induces sporulation in vitro.

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Section: Lsolation Of Prespore Cellsmentioning

confidence: 99%

Efficient Induction of Sporulation of Dictyostelium Prespore Cells by 8‐Bromocyclic AMP under Both Submerged‐ and Shaken‐Culture Conditions and Involvement of Protein Kinase(s) in Its Action

Maeda

1992

Dev Growth Differ

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“…and (3) How sensitive is the organism to this signal? In 1947 Bonner (6) proposed the hypothesis that the cells move towards an aggregate by measuring a spatial gradient of concentration over its total length. In the present work, evidence in favor of such a hypothesis is given by comparison of the mathematical parameters of a gradient formed by diffusion to the characteristics of the threshold amoeba response.…”

mentioning

confidence: 99%

Signal input for a chemotactic response in the cellular slime mold Dictyostelium discoideum.

Mato¹,

Losada²,

Nanjundiah³

et al. 1975

Proc. Natl. Acad. Sci. U.S.A.

114

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ABSRACT Drops with different concentrations of 3':5'-cyclic AMP were deposited at various distances from small populations of Dictyostelium discoideum amoebae, and the distances over which 50% of the amoebae drops reacted positively were determined. The linear regression analysis of a double logarithmic plot of distance against concentration gives a straight line with a slope of 1/4.25, which value suggests that the amoebae respond to a spatial gradient of cyclic AMP concentration. The threshold value for the signal is 3.6 X 10-9 M/mm, with a sensitivity of measurement of about 1%. These findings are discussed in relation to our present knowledge of cyclic AMP receptors. Triggered by starvation, single amoebae of the cellular slime molds aggregate and develop a differentiated multicellular organism (1). In the larger species of Dictyostelium cell aggregation is mediated by 3':5'-cyclic AMP (2); amoebae move towards the aggregation center periodically (3), probably due to a periodic release of cyclic AMP from the center. Cyclic AMP signals are recognized by a cell-membranebound cyclic AMP receptor (4, 5), only present in those species that use cyclic AMP as the chemotactic molecule (5).Some of the most interesting questions about how cyclic AMP signals can be translated into directed movement are: (1) What precisely is the macroscopic signal input? (2) How is the signal measured by an individual cell? and (3) How sensitive is the organism to this signal? In 1947 Bonner (6) proposed the hypothesis that the cells move towards an aggregate by measuring a spatial gradient of concentration over its total length. In the present work, evidence in favor of such a hypothesis is given by comparison of the mathematical parameters of a gradient formed by diffusion to the characteristics of the threshold amoeba response. Also a threshold value for this gradient has been obtained and the sensitivity of amoebae to cyclic AMP has been measured. METHODS AND TECHNIQUESAmeebe of D. discoideum, NC-4, were grown in associatWon wb£ rkcha coli on a solid medium, harvested in the ptive stage, freed of bacteria, and adjusted to 5 X 10' cells per ml with a 1% saline solution (7). Small drop (0.1 p1) of ths cell suspension were placed on hydrophobic aSr, giving a final radius of 0.3 mm. The chemotactic acSthiy of cyclic AMP (concentration ranging from 10-7 to 104 M) was tested when the amoebae were close to aggregation (8). Cyclic AMP drops (0.1 ,.) were placed at different distances from the amoebae populations (40 per given distance). The distance-measured between the centers of both drops-at which 50% of the amoebae populations react positively for a given cyclic AMP concentration was taken as the threshold distance for chemotaxis. The chemotactic response was called positive when more than twice as many cells pressed against the margin closest to the attracting drop as against the opposite side. The chemotactic response was observed at different time intervals after the deposition of the cyclic AMP drop (from 15 to 30 min) to get the...

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“…Starvation of the cells induces periodic secretion of cyclic AMP (cAMP). cAMP mediates the aggregation of the single cells into a multicellular structure by acting as chemoattractant [1,2], The chemotactie stimulation of D. discoideum cells leads to a diversity of transient intracellular responses [3,4]. Among these responses there are fluxes of different ions: H +, K + and Ca z÷ [5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Chemoattractant‐induced membrane hyperpolarization in Dictyostelium discoideum A possible role for cyclic GMP

Duijn

Wang

1990

FEBS Letters

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Membrane potentials of the cellular slime mold Dictyostelium discoideum were monitored after chemotactic stimulation by measuring the distribution of the lipophilic cation tetraphenylphosphonium. Stimulation with the chemoattractant cAMP induces a transient membrane hyperpolarization which reaches its most negative value between 1 3 min after stimulation. This hyperpolarization is consistent with the opening of potassium channels. Measurements in streamer F mutant cells reveal that cGMP likely plays a role in the regulation of the cAMP‐induced hyperpolarization.

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Evidence for the formation of cell aggregates by chemotaxis in the development of the slime mold Dictyostelium discoideum

Cited by 812 publications

References 11 publications

Efficient Induction of Sporulation of Dictyostelium Prespore Cells by 8‐Bromocyclic AMP under Both Submerged‐ and Shaken‐Culture Conditions and Involvement of Protein Kinase(s) in Its Action

Efficient Induction of Sporulation of Dictyostelium Prespore Cells by 8‐Bromocyclic AMP under Both Submerged‐ and Shaken‐Culture Conditions and Involvement of Protein Kinase(s) in Its Action

Signal input for a chemotactic response in the cellular slime mold Dictyostelium discoideum.

Chemoattractant‐induced membrane hyperpolarization in Dictyostelium discoideum A possible role for cyclic GMP

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