scholarly journals Regulation of development in Dictyostelium discoideum. IV. Effects of ions on the rate of differentiation and cellular response to cyclic AMP.

1980 ◽  
Vol 87 (3) ◽  
pp. 823-827 ◽  
Author(s):  
F T Marin ◽  
F G Rothman
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Early Development ◽  
Maximum Rate ◽  
Cellular Response ◽  
Developmental Regulation ◽  
Intrinsic Rate ◽  
Rate Of Development ◽  
High Concentrations ◽  
Early Developmental

The effects of ionic environment on both the intrinsic rate of differentiation and the response to exogenous cyclic AMP in Dictyostelium discoideum have been examined. K+ specifically inhibits the rate of early development when present at concentrations > 15 mM. Na+ does not inhibit at concentrations up to 25 mM, and can partially overcome K+ inhibition. The maximum rate of development also depends upon the presence of adequate levels of extracellular Ca++. The effect of exogenous cyclic AMP on the rate of development is inhibited by the absence of Ca++, and/or the presence of high concentrations of K+. Under optimal ionic conditions, the only effect of exogenous cyclic AMP on early developments of K+. Under optimal ionic conditions, the only effect of exogenous cyclic AMP on early development is a specific inhibition. The implications of these results for current models of early developmental regulation are discussed.

scholarly journals Properties and developmental regulation of an α-d-galactosidase from Dictyostelium discoideum

1976 ◽  
Vol 158 (2) ◽  
pp. 409-417 ◽  
Author(s):  
D C Kilpatrick ◽  
J L Stirling
Keyword(s):  
Protein Synthesis ◽  
Dictyostelium Discoideum ◽  
Early Development ◽  
Subcellular Distribution ◽  
De Novo ◽  
Specific Activity ◽  
Soluble Fraction ◽  
Developmental Regulation ◽  
Cellular Slime Mould ◽  
Cellular Slime

An alpha-D-galactosidase was detected in cells of the cellular slime mould, Dictyostelium discoideum, at all stages of development. Its specific activity was highest during early development (interphase), and this accumulation of enzyme appears to require protein synthesis de novo. Its subcellular distribution differs from that of other D. discoideum glycosidases, since most activity was recovered in the soluble fraction. No evidence was obtained for more than one isoenzymic form after subjection of extracts to electrophoresis and various chromatographic procedures. It is excreted from the cell during development, but no evidence was found for an extracellular function for the enzyme.

Oscillations and cell development in Dictyostelium discoideum stimulated by folic acid pulses

1977 ◽  
Vol 27 (1) ◽  
pp. 105-114
Author(s):  
B. Wurster ◽  
K. Schubiger
Keyword(s):  
Folic Acid ◽  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Cell Development ◽  
Biochemical Oscillations ◽  
High Concentrations ◽  
Periodic Changes

Folic acid is known to be a chemoattractant of pre-aggregation cells of Dictyostelium discoideum. When supplied in pulses, folic acid induces biochemical oscillations and stimulates the development of pre-aggregation to aggregation-competent amoebae. The continuous supply of folic acid has no stimulatory effect. Folic-acid-induced oscillations are accompanied by periodic changes in the cyclic AMP concentration. Pulses of folic acid applied with rhythms between 7 and 11 min efficiently induce oscillations. In contrast, a rhythm of 2 min neither induces oscillations nor suppresses them. Cells start to oscillate with a rhythm of about 8 min. This inherent rhythm is independent of the inducing rhythm. Oscillating cells are less sensitive to folic acid than pre-oscillating ones. They respond only to high concentrations of folic acid which also interact with the oscillating system.

Challenge with high concentrations of cyclic AMP induces transient changes in the cytosolic free calcium concentration in Dictyostelium discoideum

1994 ◽  
Vol 107 (8) ◽  
pp. 2107-2115 ◽  
Author(s):  
C. Schlatterer ◽  
F. Gollnick ◽  
E. Schmidt ◽  
R. Meyer ◽  
G. Knoll
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Free Calcium ◽  
Vegetative Cells ◽  
Phosphoinositide Signaling ◽  
Competent Cells ◽  
Dependent Protein ◽  
Free Calcium Concentration ◽  
High Concentrations ◽  
Camp Receptor

Dictyostelium discoideum cells use cyclic AMP (cAMP) for chemotactic signaling as well as for differentiation. The precise regulation of the cytosolic Ca2+ concentration ([Ca2+]i) seems to play a key role for both processes. We performed single cell measurements of [Ca2+]i in amoebae that were starved in suspension for various times and scrape-loaded with the Ca2+ indicator fura-2. Stimulation of cells with cAMP at the concentration required to induce gene expression (> or = 100 microM) elicited a global transient increase in [Ca2+]i that depended on the presence of external Ca2+. Both vegetative and aggregation-competent cells displayed a rise in [Ca2+]i, with aggregation-competent cells responding more often than vegetative cells. Basal [Ca2+]i in the presence of Ca2+ was high in vegetative cells and declined during development; the cAMP-induced rise in [Ca2+]i was higher and lasted longer in vegetative cells than in aggregative cells. The addition of 2′-deoxy-cAMP, which binds to the cAMP receptor, induced an increase in [Ca2+]i, whereas the membrane-permeant analogue 8-bromo-cAMP that has a low affinity for the receptor but activates cAMP-dependent protein kinase had no effect. This indicates that the change in [Ca2+]i is mediated by the cell surface cAMP receptor. Since HC85 mutant cells, which lack the G alpha 2 subunit of the G-protein that couples the receptor to phospholipase C, also responded to stimulation with cAMP, the Ca2+ influx does not seem to be triggered by the phosphoinositide signaling cascade.(ABSTRACT TRUNCATED AT 250 WORDS)

Clathrin heavy chain is required for spore cell but not stalk cell differentiation in Dictyostelium discoideum

Development ◽  
1997 ◽  
Vol 124 (2) ◽  
pp. 443-451
Author(s):  
M.L. Niswonger ◽  
T.J. O'Halloran
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Early Development ◽  
Heavy Chain ◽  
Mature Spore ◽  
Stalk Cell ◽  
Dictyostelium Cell ◽  
Wild Type ◽  
Lysosomal Hydrolases ◽  
Clathrin Heavy Chain

Previous studies of a clathrin-minus Dictyostelium cell line revealed important roles for clathrin heavy chain (clathrin) in endocytosis, secretion of lysosomal hydrolases and osmoregulation. In this paper, we examine the contribution of clathrin-mediated membrane traffic to development in Dictyostelium discoideum. Clathrin-minus cells were delayed in early development. When exposed to starvation conditions, clathrin-minus cells streamed and aggregated more slowly than wild-type cells. Although clathrin-minus cells displayed only 40% the level of extracellular cyclic AMP binding normally found in wild-type cells, they responded chemotactically to extracellular cyclic AMP. Clathrin-minus cells down-regulated cyclic AMP receptors, but only to half the extent of wild-type cells. We found that the extent of development of clathrin-minus cells was variable and influenced by environmental conditions. Although the mutant cells always progressed beyond the tipped mound stage, the final structure varied from a finger-like projection to a short, irregular fruiting body. Microscopic examination of these terminal structures revealed the presence of intact stalks but a complete absence of spores. Clathrin-minus cells expressed prestalk (ecmA and ecmB) and prespore (psA and cotB) genes normally, but were blocked in expression of the sporulation gene spiA. Using clathrin-minus cells that had been transformed with various promoter-lacZ reporter constructs, we saw only partial sorting of clathrin-minus prestalk and prespore cells. Even when mixed with wild-type cells, clathrin-minus cells failed to sort correctly and never constructed functional spores. These results suggest three roles for clathrin during Dictyostelium development. First, clathrin increases the efficiency of early development. Second, clathrin enables proper and efficient patterning of prestalk and prespore cells during culmination. Third, clathrin is essential for differentiation of mature spore cells.

The regulation of membrane fusion during sexual development in Dictyostelium discoideum

1989 ◽  
Vol 67 (7) ◽  
pp. 321-326 ◽  
Author(s):  
Danton H. O'Day ◽  
Michael A. Lydan
Keyword(s):  
Cyclic Amp ◽  
Membrane Fusion ◽  
Dictyostelium Discoideum ◽  
Cell Fusion ◽  
Sexual Development ◽  
Recent Literature ◽  
Developmental Regulation ◽  
Low Molecular Weight ◽  
Sexual Pheromone ◽  
Protein Cell

During the first 24 h of sexual development in Dictyostelium discoideum, three sequential events of membrane fusion occur: gamete fusion, pronuclear fusion, and phagocytosis. The early events of sexual development are regulated by a diverse group of endogenous molecules: (i) a volatile sexual pheromone, (ii) a protein cell fusion inducing factor (CFIF), (iii) a low molecular weight autoinhibitor, (iv) and cyclic AMP. CFIC enhances cell fusion while the autoinhibitor and cyclic AMP both inhibit the event. Both extracellular and intracellular calcium ions are essential for cell and pronuclear fusion. Pharmacological analyses show that the intracellular functions of the divalent cation in these processes are mediated by calmodulin. The autoinhibitor appears to function by inhibiting calmodulin activity. Glucose, mannose, and N-acetylglucosamine containing glycoproteins have been shown to function in both cell fusion and phagocytosis. The interplay between all of these diverse molecules is examined and a review of all of the recent literature is presented.Key words: biomembrane fusion, Dictyostelium, calmodulin, pheromones, cAMP, glycoproteins, developmental regulation, macrocyst, cell fusion, pronuclear fusion, calcium.

scholarly journals A cytosolic cyclic AMP-dependent protein kinase in Dictyostelium discoideum. II. Developmental regulation.

1984 ◽  
Vol 259 (1) ◽  
pp. 662-668
Author(s):  
B H Leichtling ◽  
I H Majerfeld ◽  
E Spitz ◽  
K L Schaller ◽  
C Woffendin ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Developmental Regulation ◽  
Dependent Protein Kinase ◽  
Dependent Protein

In Vitro Effects of Ethanol on Rabbit Platelet Aggregation, Secretion of Granule Contents, and Cyclic AMP Levels in the Presence of Prostacyclin

1989 ◽  
Vol 61 (02) ◽  
pp. 254-258 ◽  
Author(s):  
Margaret L Rand ◽  
Peter L Gross ◽  
Donna M Jakowec ◽  
Marian A Packham ◽  
J Fraser Mustard
Keyword(s):  
Cyclic Amp ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Inhibitory Effects ◽  
Low Concentrations ◽  
Rabbit Platelets ◽  
High Concentrations ◽  
In Vitro Effects ◽  
Aggregation Of Platelets

SummaryEthanol, at physiologically tolerable concentrations, inhibits platelet responses to low concentrations of collagen or thrombin, but does not inhibit responses of washed rabbit platelets stimulated with high concentrations of ADP, collagen, or thrombin. However, when platelet responses to high concentrations of collagen or thrombin had been partially inhibited by prostacyclin (PGI2), ethanol had additional inhibitory effects on aggregation and secretion. These effects were also observed with aspirin- treated platelets stimulated with thrombin. Ethanol had no further inhibitory effect on aggregation of platelets stimulated with ADP, or the combination of ADP and epinephrine. Thus, the inhibitory effects of ethanol on platelet responses in the presence of PGI2 were very similar to its inhibitory effects in the absence of PGI2, when platelets were stimulated with lower concentrations of collagen or thrombin. Ethanol did not appear to exert its inhibitory effects by increasing cyclic AMP above basal levels and the additional inhibitory effects of ethanol in the presence of PGI2 did not appear to be brought about by further increases in platelet cyclic AMP levels.

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
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