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

1982 ◽  
Vol 92 (3) ◽  
pp. 807-821 ◽  
Author(s):  
R P Futrelle ◽  
J Traut ◽  
W G McKee
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
System Analysis ◽  
Natural Populations ◽  
Time Lapse ◽  
Cell Behavior ◽  
Motion Data ◽  
Oriented Movement ◽  
Scattering Response ◽  
Cell Motion

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.

The evolution of excitable behaviour in Dictyostelium

1979 ◽  
Vol 36 (1) ◽  
pp. 311-321
Author(s):  
A.J. Lax
Keyword(s):  
Gene Expression ◽  
Wave Propagation ◽  
Light Scattering ◽  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Cyclic Nucleotides ◽  
Camp Phosphodiesterase ◽  
Low Concentration ◽  
Scattering Response

Aggregation of Dictyostelium discoideum amoebae is effected by relayed cyclic AMP (cAMP) signals. The period of this wave propagation drops abruptly at the transition from aggregative to post-aggregative development. In this paper I demonstrate that the light-scattering response induced by a low concentration pulse of cAMP evolves from one lasting 5 min to one lasting 2 min.The definitive establishment of the 2-min response coincides with the beginning of post-aggregative gene expression. Amoebae at the aggregative stage are unable to respond to a second cAMP pulse delivered less than 4 min after the first, whereas at the post-aggregative stage they can respond to 2 pulses separated by 1 min or longer. Addition of cAMP phosphodiesterase to amoebae at the aggregative stage can in part mimic the change in excitable behaviour: the response is shortened and the amoebae can respond more frequently. However, the shortened response is not post-aggregative in shape and the prolonged presence of cyclic nucleotides induces different responses at the aggregative and post-aggregative stage. Both these results suggest that the rate of destruction of the relayed signal is not solely responsible for the change in excitability.

The cellular basis of movement of the migrating grex of the slime mould Dictyostelium discoideum: chemotactic and reaggregation behaviour of grex cells

Development ◽  
1974 ◽  
Vol 32 (1) ◽  
pp. 57-68
Author(s):  
D. R. Garrod
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Small Groups ◽  
Short Distance ◽  
Time Lapse ◽  
Adhesive Property ◽  
Intercellular Contacts ◽  
Stage Process ◽  
Chemotactic Behaviour ◽  
Time Lapse Photography

The chemotactic behaviour of cells of the migrating grex of D. discoideum has been studied by observing the responses of small groups of cells placed near to aggregation streams, agar blocks containing cyclic AMP or migrating grexes. Grex cells placed near aggregation streams were not attracted to the streams initially; after about 1 h, however, some cells were attracted to the streams. Similarly, grex cells placed near agar blocks containing cyclic AMP were not initially attracted towards the blocks, but some attraction was observed after about 1 h; the most effective cyclic AMP concentration was 10–4m. Grex cells which were placed in heaps against the sides of aggregation streams, instead of a short distance away, were often incorporated into the streams within ½ h. Grex cells were not attracted towards migrating grexes. Because of these results it is suggested that (1) migrating grex cells are not chemotactically sensitive to cyclic AMP, but they acquire chemotactic sensitivity after separation from the grex for about 1 h; (2) chemotaxis is probably not involved in the movement of the migrating grex; (3) grex cells retain the adhesive property found in aggregating cells, which is involved in the formation of end-to-end contacts necessary for the behaviour known as contact following. Reaggregation of dispersed grex cells was studied by time-lapse photography. Reaggregation was found to be a two-stage process: first, an adhesive phase dependent on the development of intercellular contacts at the expense of adhesions with the substratum; secondly, a chemotactic phase which begins about 1 h after dispersal of the grex cells. It is suggested that the first phase may be accounted for by assuming that the cells are more cohesive than adhesive.

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.

scholarly journals A cytosolic cyclic AMP-dependent protein kinase in Dictyostelium discoideum. I. Properties.

1984 ◽  
Vol 259 (1) ◽  
pp. 654-661 ◽  
Author(s):  
I H Majerfeld ◽  
B H Leichtling ◽  
J A Meligeni ◽  
E Spitz ◽  
H V Rickenberg
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Dependent Protein Kinase ◽  
Dependent Protein

Identification of nuclear substrates of the cyclic AMP-dependent protein kinase in Dictyostelium discoideum

1987 ◽  
Vol 20 (4) ◽  
pp. 217-230 ◽  
Author(s):  
Timothy C. Chambers ◽  
Joan Song-Nichols ◽  
David S. Campbell ◽  
Eva Spitz ◽  
Ben H. Leichtling ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Dependent Protein Kinase ◽  
Dependent Protein

scholarly journals Cyclic AMP and folic acid mediated cyclic GMP accumulation in Dictyostelium discoideum

FEBS Letters ◽  
1977 ◽  
Vol 79 (2) ◽  
pp. 331-336 ◽  
Author(s):  
José M. Mato ◽  
Peter J.M. Van Haastert ◽  
Frans A. Krens ◽  
Els H. Rhunsburger ◽  
Fred C.P.M. Dobbe ◽  
...  
Keyword(s):  
Folic Acid ◽  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Cyclic Gmp

Pharmacological characterization of cyclic AMP receptors mediating gene regulation in Dictyostelium discoideum

1986 ◽  
Vol 6 (7) ◽  
pp. 2402-2408
Author(s):  
B Haribabu ◽  
R P Dottin
Keyword(s):  
Gene Expression ◽  
Cyclic Amp ◽  
Cell Surface ◽  
Dictyostelium Discoideum ◽  
Cell Surface Receptor ◽  
Intracellular Camp ◽  
Response Curves ◽  
Pharmacological Characterization ◽  
Surface Receptor ◽  
Extracellular Molecules

Extracellular molecules regulate gene expression in eucaryotes. Exogenous cyclic AMP (cAMP) affects the expression of a large number of developmentally regulated genes in Dictyostelium discoideum. Here, we determine the specificity of the receptor(s) which mediates gene expression by using analogs of cAMP. The order of potency with which these analogs affect the expression of specific genes is consistent with the specificity of their binding to a cell surface receptor and is distinct from their affinity for intracellular cAMP-dependent protein kinase. Dose-response curves with cAMP and adenosine 3',5'-monophosphorothioate, a nonhydrolyzable analog, revealed that the requirement for high concentrations of exogenous cAMP for regulating gene expression is due to the rapid degradation of cAMP by phosphodiesterase. The addition of low concentrations of cAMP (100 nM) or analogs in pulses also regulates gene expression. Both the genes that are positively regulated by exogenous cAMP and the discoidin gene, which is negatively regulated, respond to cAMP analogs to the same degree. Genes expressed in prespore or prestalk cells are also similarly regulated. These data suggest that the effects are mediated through the same receptor. The specificity of this receptor is indistinguishable from that of the well-characterized cell surface cAMP receptor.

Spike-shaped oscillations in the absence of measurable changes in cyclic AMP concentration in a mutant of Dictyostelium discoideum

1987 ◽  
Vol 87 (5) ◽  
pp. 723-730
Author(s):  
B. Wurster ◽  
R. Mohn
Keyword(s):  
Light Scattering ◽  
Cyclic Amp ◽  
Cell Surface ◽  
Dictyostelium Discoideum ◽  
Cyclic Gmp ◽  
Parent Strain ◽  
Reaction System ◽  
Cell Suspensions ◽  
Deficient Mutant ◽  
Cyclic Amp Synthesis

Periodic activities of Dictyostelium discoideum cells involve two types of oscillations, spike-shaped and sinusoidal. Spike-shaped oscillations are accompanied by the periodic synthesis and release of cyclic AMP, and cyclic AMP-activated cyclic AMP synthesis is believed to control these oscillations. Experiments described here call into question the importance of cyclic AMP in spike-shaped oscillations. Cell suspensions of strain agip43, an aggregation-deficient mutant of D. discoideum, displayed spike-shaped oscillations in light scattering with period lengths about 1.5 times larger than those of the parent strain. These oscillations were not accompanied by measurable oscillations of cyclic AMP and cyclic GMP. Applied cyclic AMP pulses elicited increases of two- to threefold in the cyclic AMP level and increases of seven- to ninefold in the cyclic GMP concentration. Cyclic AMP additions caused phase shifts in the oscillations of agip43 cells, suggesting that cyclic AMP receptors at the cell surface communicate with the oscillator. We interpret these results in terms of an oscillator not based on cyclic AMP. This oscillator should be coupled to the reaction system involving cyclic AMP synthesis and release. The latter can operate in an oscillatory manner in the parent strain Ax2 but not in mutant agip43.

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