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Enzyme synthesis in myxamoebae of the cellular slime mould Dictyostelium discoideum during growth in axenic culture.

ABSTRACT: 1. The specific activities of beta-N-acetylglucosaminidase, acid phosphatase, alpha-mannosidase, beta-glucosidase, UDP-glucose pyrophosphorylase and alkaline phosphatase have been determined in myxamoebae of the cellular slime mould Dictyostelium discoideum Ax-2 grown on different media and in different phases of the growth cycle. 2. Variations in enzymic composition occur with changes in growth medium and phase of the growth cycle. 3. The intracellular location of the enzymes studied has been determined. 4. Two enzymes, beta-N-acetylglucosaminidase and alpha-mannosidase, are not only synthesized preferentially as the myxamoebae enter the stationary phase of growth but they are also excreted. The excretion process appears to be specific, because other enzymes that occur in the same intracellular fraction are not excreted.

SUBMITTER: Ashworth JM

PROVIDER: S-EPMC1178417 | biostudies-other | 1972 Feb

REPOSITORIES: biostudies-other

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Metabolism of the cellular slime mould Dictyostelium discoideum grown in axenic culture.

Project description:1. The DNA, RNA, protein and carbohydrate contents of myxamoebae of Dictyostelium discoideum strain Ax-2 were measured after growth on bacteria or in various axenic media. 2. Myxamoebae grown in the different axenic media have similar DNA, RNA and protein contents, but there are marked differences in the contents of glycogen and free sugars. The DNA and protein contents of myxamoebae grown on bacteria are different from those in myxamoebae grown axenically. 3. Approximately half the DNA found in myxamoebae grown on bacteria is of bacterial rather than of slime-mould origin. 4. The specific activities of some enzymes (including UDP-glucose pyrophosphorylase) are higher in myxamoebae grown axenically than in myxamoebae grown on bacteria. Nevertheless the characteristic increase in the specific activity of UDP-glucose pyrophosphorylase occurring during differentiation of cells of the wild-type strain NC-4 is also found in cells grown axenically. 5. The rate of amino acid oxidation during axenic growth of the myxamoebae is decreased when the cells are supplied with glucose.

| S-EPMC1179340 | biostudies-other

Growth of myxameobae of the cellular slime mould Dictyostelium discoideum in axenic culture.

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| S-EPMC1179339 | biostudies-other

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

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| S-EPMC1178418 | biostudies-other

The isolation and characterization of lysosomal particles from myxamoebae of the cellular slime mould Dictyostelium discoideum.

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Putrescine uptake by the cellular slime mould dictyostelium discoideum.

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The metabolism of macromolecules during the differentiation of Myxamoebae of the cellular slime mould Dictyostelium discoideum containing different amounts of glycogen.

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| S-EPMC1168281 | biostudies-other

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

Project description: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.

| S-EPMC1177810 | biostudies-other

Adenosine 3':5'-cyclic monophosphate-binding protein from the cellular slime mould Dictyostelium discoideum.

Project description: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.

| S-EPMC1177739 | biostudies-other

The purification and properties of extracellular glycosidases of the cellular slime mould Dictyostelium discoideum.

Project description:The purification of beta-N-acetylhexosaminidase, alpha-glucosidase, alpha-mannosidase and beta-glucosidase from the spent growth medium of Dictyostelium discoideum strain Ax-2 myxamoebae is described. beta-N-Acetylhexosaminidase and alpha-glucosidase were obtained in high yield and as homogeneous preparations whereas the alpha-mannosidase preparation consisted of two electrophoretically distinct isoenzymes. The physical, chemical and kinetic properties of these enzymes are described.

| S-EPMC1177668 | biostudies-other

The isolation and subfractionation of plasma membrane from the cellular slime mould Dictyostelium discoideum.

Project description:A procedure for the isolation and separation of three different subfractions of plasma membrane from the cellular slime mould Dictyostelium discoideum is described. The cells were disrupted by freeze-thawing in liquid N(2) and plasma membranes were purified by equilibrium centrifugation in a sucrose gradient. The cell surface was labelled with radioactive iodide by using the lactoperoxidase iodination method. Alkaline phosphatase was identified as a plasma-membrane marker by its co-distribution with [(125)I]iodide. 5'-Nucleotidase, which has been widely described as a plasma-membrane marker enzyme in mammalian tissues, was not localized to any marked extent in D. discoideum plasma membrane. The isolated plasma membranes showed a 24-fold enrichment of alkaline phosphatase specific activity relative to the homogenate and a yield of 50% of the total plasma membranes. Determination of succinate dehydrogenase and NADPH-cytochrome c reductase activities indicated that the preparation contained 2% of the total mitochondria and 3% of the endoplasmic reticulum. When the plasma-membrane preparation was further disrupted in a tight-fitting homogenizer, three plasma-membrane subfractions of different densities were obtained by isopycnic centrifugation. The enrichment of alkaline phosphatase was greatest in the subfraction with the lowest density. This fraction was enriched 36-fold relative to the homogenate and contained 19% of the total alkaline phosphatase activity but only 0.08% of the succinate dehydrogenase activity and 0.34% of the NADPH-cytochrome c reductase activity. Electron microscopy of this fraction showed it to consist of smooth membrane vesicles with no recognizable contaminants.

| S-EPMC1168002 | biostudies-other

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