scholarly journals Adenosine 3′:5′-cyclic monophosphate-binding protein from the cellular slime mould Dictyostelium discoideum (Short Communication)

1973 ◽  
Vol 133 (3) ◽  
pp. 601-603 ◽  
Author(s):  
Al M. Malkinson ◽  
Janet Kwasniak ◽  
John M. Ashworth
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Short Communication ◽  
Specific Activity ◽  
Binding Protein ◽  
Protein S ◽  
Fold Increase ◽  
Axenic Medium ◽  
Cellular Slime Mould ◽  
Cellular Slime

During the differentiation of myxamoebae of Dictyostelium discoideum strain Ax-2 grown in axenic medium there is a seven- to ten-fold increase in the specific activity of cyclic AMP-binding protein(s). Evidence is presented for the belief that cyclic AMP phosphodiesterase and cyclic AMP-binding protein are distinct molecular species.

scholarly journals Growth of myxamoebae of the cellular slime mould Dictyostelium discoideum in axenic culture

1970 ◽  
Vol 119 (2) ◽  
pp. 171-174 ◽  
Author(s):  
D. J. Watts ◽  
J. M. Ashworth
Keyword(s):  
Cell Differentiation ◽  
Dictyostelium Discoideum ◽  
Axenic Culture ◽  
Axenic Medium ◽  
Cellular Slime Mould ◽  
Slime Mould ◽  
Solid Media ◽  
Cellular Slime

1. A simple axenic medium suitable for the growth of the myxamoebae of a strain of the cellular slime mould Dictyostelium discoideum is described. 2. Procedures suitable for the growth of this strain in liquid and on solid media are described. 3. Conditions suitable for initiating the cell differentiation of myxamoebae grown axenically are described.

scholarly journals Adenosine 3′:5′-cyclic monophosphate concentrations and phosphodiesterase activities during axenic growth and differentiation of cells of the cellular slime mould Dictyostelium discoideum

1973 ◽  
Vol 134 (1) ◽  
pp. 311-319 ◽  
Author(s):  
A. M. Malkinson ◽  
J. M. Ashworth
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Exponential Phase ◽  
Axenic Medium ◽  
Fruiting Body Formation ◽  
Solid Media ◽  
Cellular Slime ◽  
Second Peak ◽  
Axenic Growth ◽  
Approximate Doubling

During growth of myxamoebae of Dictyostelium discoideum (strain Ax-2) in axenic medium, the myxamoebae secrete cyclic AMP. As the cells leave the exponential phase of growth and enter the stationary phase, there is an approximate doubling of the intracellular cyclic AMP content, but the amount of extracellular cyclic AMP remains proportional, at all times, to the number of myxamoebae present. During development of axenically grown myxamoebae, there is first a rise in the intracellular concentration of cyclic AMP, followed by a rise in the amount of extracellular cyclic AMP, which reaches a peak at the time of aggregation and then declines. There is a second peak in the amount of extracellular cyclic AMP found at the time of fruiting-body formation, but this second peak is not associated with a rise in the intracellular cyclic AMP concentration. Controls thus exist over the synthesis and secretion of cyclic AMP. Evidence is presented for the belief that the activity of the adenylate cyclase enzyme controls the amount of cyclic AMP synthesized rather than the activity or amount of cyclic AMP phosphodiesterase present. Similar changes occur in extracellular cyclic AMP and phosphodiesterase concentrations during incubation of myxamoebae in buffered suspensions to those occuring during the first few hours of development of such cells on solid media, but the timing of these changes is different.

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.

scholarly journals Enzyme synthesis in the cellular slime mould Dictyostelium discoideum during the differentiation of myxamoebae grown axenically

1972 ◽  
Vol 126 (3) ◽  
pp. 609-615 ◽  
Author(s):  
J. Quance ◽  
J. M. Ashworth
Keyword(s):  
Alkaline Phosphatase ◽  
Acid Phosphatase ◽  
Cell Differentiation ◽  
Dictyostelium Discoideum ◽  
Specific Activity ◽  
Enzyme Synthesis ◽  
Cellular Slime Mould ◽  
Slime Mould ◽  
Cellular Slime ◽  
Developmental Programme

1. Myxamoebae of the cellular slime mould Dictyostelium discoideum Ax-2 were grown on different media, and were harvested either in the stationary or exponential phases of the growth cycle to yield samples of myxamoebae differing in enzymic composition. 2. Morphogenesis and cell differentiation phenomena in D. discoideum appear to be similar in myxamoebae grown and harvested under different conditions. 3. The specific activity of the enzymes β-N-acetylglucosaminidase, acid phosphatase, α-mannosidase, β-glucosidase and alkaline phosphatase have been determined during cell differentiation of myxamoebae grown and harvested under different conditions. 4. The pattern of synthesis of these enzymes, all of which have been claimed to be part of the ‘developmental programme’, either remains unaffected despite the origin of the myxamoebae (alkaline phosphatase) or is qualitatively similar but quantitatively affected (acid phosphatase, β-glucosidase) or is both qualitatively and quantitatively affected by changes in the myxamoebae (α-mannosidase, β-N-acetylglucosaminidase). 5. The implications of these results for the concept of a ‘developmental programme‘ are discussed.

Inositol 1,4,5-trisphosphate and calcium stimulate actin polymerization in Dictyostelium discoideum

1986 ◽  
Vol 82 (1) ◽  
pp. 41-51
Author(s):  
G.N. Europe-Finner ◽  
P.C. Newell
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Actin Polymerization ◽  
Cell Surface Receptor ◽  
Receptor Stimulation ◽  
Normal Cells ◽  
Cellular Slime Mould ◽  
Inositol 1,4,5 Trisphosphate ◽  
Surface Receptor ◽  
Cellular Slime

The effect of chemoattractants such as cyclic AMP and folate on amoebae of the cellular slime mould Dictyostelium discoideum is to cause a series of rapid intracellular responses. One of the most rapid of these responses is the polymerization of actin associated with the cytoskeleton, an event correlated with pseudopodium formation, which occurs within 3–5 s of chemotactic receptor stimulation. We report that this response can be mimicked by addition of 5 microM-inositol 1,4,5-triphosphate (IP3) or by addition of 100 microM-Ca2+ to saponin-permeabilized amoebae. The data suggest that cytoskeletal actin polymerization occurs in normal cells as a result of IP3 formation in response to cell surface receptor stimulation and the consequent release of Ca2+ from internal stores.

scholarly journals 6-Phosphogluconate dehydrogenase and the assay of uridine diphosphate glucose pyrophosphorylase in the cellular slime mould Dictyostelium discoideum

1972 ◽  
Vol 126 (3) ◽  
pp. 593-600 ◽  
Author(s):  
T. D. Edmundson ◽  
J. M. Ashworth
Keyword(s):  
Cell Differentiation ◽  
Dehydrogenase Activity ◽  
Dictyostelium Discoideum ◽  
Specific Activity ◽  
Uridine Diphosphate ◽  
Cellular Slime Mould ◽  
Slime Mould ◽  
Phosphogluconate Dehydrogenase ◽  
Cellular Slime ◽  
Diphosphate Glucose

1. 6-Phosphogluconate dehydrogenase activity is present in all morphogenetic stages during cell differentiation in the cellular slime mould. 2. The different ratios of 6-phosphogluconate dehydrogenase/UDP-glucose pyrophosphorylase observed during this process can render spectrophotometric assays of UDP-glucose pyrophosphorylase inaccurate. 3. The disputed occurrence of increases in specific activity of UDP-glucose pyrophosphorylase during cell differentiation in the cellular slime mould is discussed in the light of these observations.

Genetics of Growth in Axenic Medium of the Cellular Slime Mould Dictyostelium discoideum

Nature ◽  
1974 ◽  
Vol 247 (5437) ◽  
pp. 142-143 ◽  
Author(s):  
KEITH LESLIE WILLIAMS ◽  
RICHARD H. KESSIN ◽  
PETER C. NEWELL
Keyword(s):  
Dictyostelium Discoideum ◽  
Axenic Medium ◽  
Cellular Slime Mould ◽  
Slime Mould ◽  
Cellular Slime

scholarly journals Glycogen synthetase and the control of glycogen synthesis in the cellular slime mould Dictyostelium discoideum during the growth (myxamoebal) phase

1972 ◽  
Vol 126 (3) ◽  
pp. 617-626 ◽  
Author(s):  
G. Weeks ◽  
J. M. Ashworth
Keyword(s):  
Stationary Phase ◽  
Dictyostelium Discoideum ◽  
Glycogen Content ◽  
Glycogen Synthesis ◽  
Axenic Medium ◽  
Glycogen Accumulation ◽  
Cellular Slime Mould ◽  
Slime Mould ◽  
Glycogen Synthetase ◽  
Cellular Slime

1. Myxamoebae of the cellular slime mould Dictyostelium discoideum Ax-2 that are grown in axenic medium containing 86mm-glucose have seven times the glycogen content of the same myxamoebae grown in the same medium but lacking added carbohydrate. 2. During the transition from the exponential to the stationary phase of growth in axenic medium containing glucose myxamoebae preferentially synthesize glycogen and can have as much as three times the glycogen content during the stationary phase as they have during the exponential phase of growth. 3. The rate of glycogen degradation by myxamoebae is, under all conditions of growth, small compared with the rate of glycogen accumulation and the changes in glycogen content thus reflect altered rates of glycogen synthesis. 4. There is no correlation between the rate of glycogen synthesis by myxamoebae and the glycogen synthetase content of the myxamoebae. 5. The activity of glycogen synthetase of D. discoideum is inhibited by a physiological concentration of ATP and this inhibition is overcome by glucose 6-phosphate. Both effects are especially marked at physiological concentrations of UDP-glucose. 6. The rate of glycogen accumulation by myxamoebae growing exponentially in axenic media can be satisfactorily accounted for in terms of the known intracellular concentrations of glucose 6-phosphate, UDP-glucose and glycogen synthetase. The rate-limiting factors controlling glycogen synthesis by the myxamoebae are apparently the substrate (UDP-glucose) and effector (glucose 6-phosphate and ATP) concentrations rather than the amount of the enzyme.

Plasma Components which Interfere with Ristocetin-induced Platelet Aggregation

1975 ◽  
Vol 33 (03) ◽  
pp. 540-546 ◽  
Author(s):  
Robert F Baugh ◽  
James E Brown ◽  
Cecil Hougie
Keyword(s):  
Platelet Aggregation ◽  
Human Plasma ◽  
Plasma Proteins ◽  
Binding Protein ◽  
Plasma Heating ◽  
Protein S ◽  
Fold Increase ◽  
Normal Human Plasma ◽  
Preliminary Examination ◽  
Normal Human

SummaryNormal human plasma contains a component or components which interfere with ristocetin-induced platelet aggregation. Preliminary examination suggests a protein (or proteins) which binds ristocetin and competes more effectively for ristocetin than do the proteins involved in ristocetin-induced platelet aggregation. The presence of this protein in normal human plasma also prevents ristocetin-induced precipitation of plasma proteins at levels of ristocetin necessary to produce platelet aggregation (0.5–2.0 mg/ml). Serum contains an apparent two-fold increase of this component when compared with plasma. Heating serum at 56° for one hour results in an additional 2 to 4 fold increase. The presence of a ristocetin-binding protein in normal human plasma requires that this protein be saturated with ristocetin before ristocetin-induced platelet aggregation will occur. Variations in the ristocetin-binding protein(s) will cause apparent discrepancies in ristocetin-induced platelet aggregation in normal human plasmas.

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