scholarly journals Rates of accumulation of glycosidase activities during growth and differentiation of Dictyostelium discoideum

1975 ◽  
Vol 148 (2) ◽  
pp. 161-167 ◽  
Author(s):  
D Every ◽  
J M Ashworth
Keyword(s):  
Life Cycle ◽  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Growth Medium ◽  
Specific Activity ◽  
Growth Conditions ◽  
Cellular Protein ◽  
Total Cellular Protein ◽  
Early Differentiation ◽  
Rate Of Accumulation

1. The rates of accumulation (enzyme units/h per 10(8) cells) of a number of glycosidase activities were studied in Dictyostelium discoideum cells during the growth and differentiation phases of this organism's life cycle. 2. The rates of accumulation of the enzymes β-N-acetylglucosaminidase, α-glucosidase and β-galactosidase remain unchanged during the growth and early differentiation phases. 3. The considerable changes in specific activity of the enzymes which occur in the early differentiation phase are due to the massive loss of total cellular protein which occurs at this time. 4. Significant alterations can occur in the rates of accumulation of α-mannosidase during both the growth and differentiation phases, and since, on the onset of differentiation, β-glucosidase activity is excreted and degraded, the rate of accumulation of this enzyme differs in the growth and differentiation phases. 5. The characteristic rates of accumulation of all these glycosidases change markedly with changes in the growth conditions of the myxamoebae, and thus these rates of synthesis must be regulated independently; however, addition of cyclic AMP to the growth medium has no effect on them.

scholarly journals Developmentally regulated enzymes and cyclic AMP-binding sites in Dictyostelium discoideum cells blocked during development by α-chymotrypsin

1982 ◽  
Vol 206 (2) ◽  
pp. 185-193
Author(s):  
J A Schmidt ◽  
J L Stirling
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Binding Sites ◽  
Glycogen Phosphorylase ◽  
Specific Activity ◽  
Tyrosine Aminotransferase ◽  
Carbohydrate Binding ◽  
Threonine Deaminase ◽  
Developmentally Regulated ◽  
Beta Glucosidase

When cells of the slime mould Dictyostelium discoideum are allowed to starve in the presence of alpha-chymotrypsin, they are blocked in development at the stage where tight aggregates form tips. Analysis of developmentally regulated enzymes has shown that alpha-mannosidase, beta-N-acetylglucosaminidase, threonine deaminase, tyrosine aminotransferase, beta-glucosidase and the carbohydrate-binding protein discoidin are unaffected, but enzymes that show an increase in specific activity during post-aggregative development, namely glycogen phosphorylase, UDP-glucose pyrophosphorylase, UDP-galactose 4-epimerase, UDP-galactose polysaccharide transferase and alkaline phosphatase, did not show the characteristic increase when development was blocked by alpha-chymotrypsin. Recovery of cells from the effects of alpha-chymotrypsin was accompanied by the formation of fruiting bodies and a concomitant increase in the specific activity of UDP-glucose pyrophosphorylase. Uptake or efflux of 45Ca2+ was not altered in the presence of alpha-chymotrypsin. Cells allowed to develop in alpha-chymotrypsin, or treated with the enzyme for 15 min, had a markedly reduced ability to bind cyclic AMP with low affinity; high-affinity binding was unaffected. Pronase had a similar effect on cyclic AMP binding, but trypsin, which does not alter developmental processes, has no effect on cyclic AMP binding to D. discoideum cells.

scholarly journals Rates of degradation and synthesis of glycosidases de novo during growth and differentiation of Dictyostelium discoideum

1975 ◽  
Vol 148 (2) ◽  
pp. 169-177 ◽  
Author(s):  
D Every ◽  
J M Ashworth
Keyword(s):  
Amino Acids ◽  
Enzyme Activity ◽  
Life Cycle ◽  
Dictyostelium Discoideum ◽  
Growth Medium ◽  
Growth Phase ◽  
Enzyme Activities ◽  
De Novo ◽  
Antibody Preparation ◽  
Differentiated Cells

1. Injection of a purified preparation of β-N-acetylglucosaminidase from the spent growth medium of myxamoebae of Dictyostelium discoideum into rabbits gave rise to an antibody preparation containing both anti-α-glucosidase and anti-β-acetylglucosaminidase activities. 2. These two activities were shown to reside in different immunoglobulin molecules and it was concluded that the β-N-acetylglucosaminidase preparation contained trace amounts of highly antigenic α-glucosidase. 3. A single precipitin band having β-N-acetylglucosaminidase activity was formed in Ouchterlony plates when this antibody preparation was tested against extracts obtained from differentiated cells or from myxamoebae grown either axenically or on bacteria. 4. The antibody preparation was used to show that both β-N-acetylglucosaminidase and α-glucosidase molecules are synthesized de novo from isotopically labelled amino acids during both the growth and differentiation phases of the life cycle and to show that neither of these proteins is significantly degraded during the growth phase or during the first 9h of differentiation. 5. The rates of accumulation of these assayable enzyme activities are thus equal to their rates of synthesis during growth and early differentiation. 6. The factors regulating cellular enzyme activity during the life cycle of D. discoideum are discussed.

Pattern formation in Dictyostelium discoideum

Development ◽  
1977 ◽  
Vol 40 (1) ◽  
pp. 215-228
Author(s):  
D. Forman ◽  
D. R. Garrod
Keyword(s):  
Life Cycle ◽  
Pattern Formation ◽  
Dictyostelium Discoideum ◽  
Cell Population ◽  
Growth Conditions ◽  
Total Cell ◽  
Immunofluorescent Staining ◽  
Fruiting Bodies ◽  
Fluorescent Intensity ◽  
Total Cell Population

Immunofluorescent staining of the prespore cells of the cellular slime mould Dictyostelium discoideum was carried out using a heterologous spore antibody. The highly specific staining of the prespore vesicles (PSVs) within the prespore cells enabled quantitative determinations to be made of the rate and extent of development of these cells throughout the life cycle. The results showed that PSVs first appeared in a large proportion of the cells shortly after the cells had chemotactically aggregated into multicellular masses. During the later phases of the life cycle, the proportion of cells containing PSV increased, as did the fluorescent intensity of their PSVs, until the early culmination stage of development when 85–90 % of the total cell population contained PSVs. Lowering the temperature of development delayed the onset of vesicle formation and decreased the proportion of prespore cells in the total cell population. Changing the growth conditions of the cells prior to multicellular development also had a significant effect on the proportions of prespore cells, as did the use of a mutant known to give rise to fruiting bodies with a reduced number of spores. The comparability between these estimates of prespore cell proportions at culmination and previously reported spore:stalk ratios within fruiting bodies confirms the view that PSVs are reliable indicators of prespore cells. The finding that temperature and growth conditions and the use of mutants all of which are known to affect spore:stalk ratios, also all affected prespore proportions in the expected direction, adds further weight to this argument. The fact that prespore cells are beginning to differentiate early in the multicellular phase of the life cycle and the related finding that such differentiation always precedes formation of the grex tip are results of considerable importance to the development of a model for pattern formation in D. discoideum.

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 Structural and biochemical aspects of cell motility in amebas of Dictyostelium discoideum.

1977 ◽  
Vol 72 (2) ◽  
pp. 339-350 ◽  
Author(s):  
B S Eckert ◽  
R H Warren ◽  
R W Rubin
Keyword(s):  
Life Cycle ◽  
Cyclic Amp ◽  
Cell Motility ◽  
Dictyostelium Discoideum ◽  
Cell Shape ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Saltatory Movement ◽  
Filament Network ◽  
Motility Rate

Amebas of Dictyostelium discoideum contain both microfilaments and microtubules. Microfilaments, found primarily in a cortical filament network, aggregate into bundles when glycerinated cells contract in response to Mg-ATP. These cortical filaments bind heavy meromyosin. Microtubules are sparse in amebas before aggregation. Colchicine, griseofulvin, or cold treatments do not affect cell motility or cell shape. Saltatory movement of cytoplasmic particles is inhibited by these treatments and the particles subsequently accumulate in the posterior of the cell. Cell motility rate changes as Dicytostelium amebas go through different stages of the life cycle. Quantitation of cellular actin by sodium dodecyl sulfate-polyacrylamide gel electrophoresis shows that the quantity of cellular actin changes during the life cycle. These changes in actin are directly correlated with changes in motility rate. Addition of cyclic AMP to Dictyostelium cultures at the end of the feeding stage prevents a decline in motility rate during the preaggregation stage. Cyclic AMP also modifies the change in actin content of the cells during preaggregation.

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

scholarly journals Isolation of a gene required for programmed initiation of development by Aspergillus nidulans.

1992 ◽  
Vol 12 (9) ◽  
pp. 3827-3833 ◽  
Author(s):  
T H Adams ◽  
W A Hide ◽  
L N Yager ◽  
B N Lee
Keyword(s):  
Life Cycle ◽  
Aspergillus Nidulans ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Nutrient Deprivation ◽  
Deletion Mutants ◽  
Wild Type ◽  
Microbial Development ◽  
Type Strains ◽  
Posttranscriptional Level

In contrast to many other cases in microbial development, Aspergillus nidulans conidiophore production initiates primarily as a programmed part of the life cycle rather than as a response to nutrient deprivation. Mutations in the acoD locus result in "fluffy" colonies that appear to grow faster than the wild type and proliferate as undifferentiated masses of vegetative cells. We show that unlike wild-type strains, acoD deletion mutants are unable to make conidiophores under optimal growth conditions but can be induced to conidiate when growth is nutritionally limited. The requirement for acoD in conidiophore development occurs prior to activation of brlA, a primary regulator of development. The acoD transcript is present both in vegetative hyphae prior to developmental induction and in developing cultures. However, the effects of acoD mutations are detectable only after developmental induction. We propose that acoD activity is primarily controlled at the posttranscriptional level and that it is required to direct developmentally specific changes that bring about growth inhibition and activation of brlA expression to result in conidiophore development.

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