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Glycogen synthetase and the control of glycogen synthesis in the cellular slime mould Dictyostelium discoideum during cell differentiation.

ABSTRACT: 1. The variation in cellular glycogen content of differentiating cells derived from myxamoebae that initially contained a wide range of glycogen contents (0.047-5.56mg of glycogen/10(8) myxamoebae) has been studied. 2. Myxamoebae that initially contained 0.047-3.62mg of glycogen/10(8) myxamoebae all gave rise to fruiting bodies that contained similar amounts of glycogen (0.06-0.11mg of glycogen/10(8) cells) but myxamoebae that initially contained 5.56mg of glycogen formed fruiting bodies containing 0.5mg of glycogen/10(8) cells. 3. Despite the high net rate of glycogen disappearance (during cell differentiation) from cells that contained more than 2mg of glycogen/10(8) cells initially, there were still significant variations in the rate of glycogen synthesis. The rate of glycogen synthesis reached a peak at the aggregation stage. 4. Evidence is presented showing that the rate of this synthesis of glycogen is controlled by factors other than the intracellular concentration of glycogen synthetase. 5. Our results are discussed in the context of the theory that the rates of glycogen synthesis and degradation act as a control mechanism for cell differentiation. 6. Criteria are discussed for deciding whether a biochemical event is causally or secondarily related to morphogenesis.

SUBMITTER: Hames BD

PROVIDER: S-EPMC1178420 | biostudies-other | 1972 Feb

REPOSITORIES: biostudies-other

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

Project description: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.

| S-EPMC1178419 | biostudies-other

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

Project description: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 beta-N-acetylglucosaminidase, acid phosphatase, alpha-mannosidase, beta-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, beta-glucosidase) or is both qualitatively and quantitatively affected by changes in the myxamoebae (alpha-mannosidase, beta-N-acetylglucosaminidase). 5. The implications of these results for the concept of a ;developmental programme' are discussed.

| S-EPMC1178418 | biostudies-other

Putrescine uptake by the cellular slime mould dictyostelium discoideum.

Project description:1. Rapid labelling occurs when myxamoebae of Dictyostelium discoideum strain AX2 are incubated with [1,4-14C]putrescine. Labelling is energy-dependent. 2. The label enters a pool from which rapid exchange with extracellular putrescine does not occur, and labelling is believed to represent uptake into the cells. 3. The concentration-dependence of putrescine uptake indicates that a number of systems are involved, at least one of which is saturable, with a Km of 9.1 micro M-putrescine. At high putrescine concentrations the overall uptake process is non-saturable. 4. Significant metabolism of putrescine and loss of intracellular putrescine to the medium only occurred when cells were incubated with millimolar concentrations of extracellular putrescine. 5. Putrescine uptake was inhibited by diamines, polyamines, bivalent metal ions and omega-aminocarboxylic acids. 6. The ability to take up putrescine at low concentrations decreased during starvation of myxamoebae. 7. The results are interpreted in terms of a model for putrescine uptake involving adsorptive pinocytosis at low concentrations and fluid-phase pinocytosis at high concentrations.

| S-EPMC1161026 | biostudies-other

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

Project description:1. Methods of obtaining myxamoebae of Dictyostelium discoideum strain Ax-2 (ATCC 24397) with glycogen contents in the range 0.05-5mg of glycogen/10(8) cells are described. The changes in cellular glycogen, protein and RNA content during the differentiation of such myxamoebae were determined. 2. Myxamoebal glycogen is not conserved during differentiation and gluconeogenesis may occur even in cells that contain a large amount of glycogen initially. 3. There is a marked net loss of cellular protein and RNA during differentiation and associated with this there are also marked decreases in the sizes of the intracellular pools of amino acids, acid-soluble proteins and pentose-containing materials. 4. During the early stages of development some protein and pentose(s) are excreted, but this cannot account for the decreased cellular content of protein and RNA. 5. There is a linear rate of production of NH(3) during development, and oxidation appears to be the fate of the major portion of the degraded protein and RNA. 6. However, provision of an alternative metabolizable energy source (glycogen) has little effect on the rate or extent of protein or RNA breakdown or on the changes in the sizes of the intracellular pools of amino acids, acid-soluble proteins and pentose-containing materials. 7. It is concluded that during development there is a requirement for the destruction of specific RNA and protein molecules for reasons other than the provision of oxidizable substrates. 8. The kinetic model of Wright et al. (1968) is discussed in relation to these changes in macromolecular content.

| S-EPMC1168281 | biostudies-other

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

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

Project description: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.

| S-EPMC1178417 | biostudies-other

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

Project description: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.

| S-EPMC1179339 | biostudies-other

Differentiation-inducing factor from the slime mould Dictyostelium discoideum and its analogues. Synthesis, structure and biological activity.

Project description:Previous work has led to the identification of a novel class of effector molecules [DIFs (differentiation-inducing factors) 1-3] released from the slime mould Dictyostelium discoideum. These substances induce stalk-cell differentiation in Dictyostelium discoideum and are thought to act as morphogens in the generation of the prestalk/prespore pattern during development. The DIFs are phenylalkan-1-ones, with chloro, hydroxy and methoxy substitution on the benzene ring. DIFs 1-3 and a number of their analogues have been synthesized by using a simple two-step procedure, and each analogue has been characterized by m.s., u.v. and n.m.r. spectroscopy. The crystal structure of synthetic DIF-1 [1-(3,5-dichloro-2,6-dihydroxy-4-methoxyphenyl)hexan-1-one, was investigated. The specific biological activity of each analogue was determined in a bioassay, where isolated Dictyostelium amoebae are induced to differentiate into stalk cells. The major biologically active substance, DIF-1, caused 50% stalk-cell differentiation at 1.8 x 10(-10) M; the C4 alkyl homologue (DIF-2) and C6 homologue possessed 40 and 16% of the activity of DIF-1 respectively. Further increase or decrease in the alkyl chain length resulted in a marked decrease in specific activity. The pattern of substitution on the benzene ring is a major determinant of bioactivity, since the specific activities of the 2,4-dihydroxy-6-methoxy and trihydroxy analogues were less than 1% of that of DIF-1. Substitution of bromine in DIF-1 had little effect on bioactivity; in contrast the activity of monochloro-DIF-1 (DIF-3) was diminished. There was no evidence for antagonism or synergy between DIF-1 and any of its analogues. This series of analogues will facilitate further studies in the biological effects and mode of action of DIF-1.

| S-EPMC1135362 | 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

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