scholarly journals Mitochondrial processing peptidase activity is controlled by the processing of α-MPP during development in Dictyostelium discoideum

Microbiology ◽  
2010 ◽  
Vol 156 (4) ◽  
pp. 978-989 ◽  
Author(s):  
Koki Nagayama ◽  
Tetsuo Ohmachi
Keyword(s):  
Life Cycle ◽  
Dictyostelium Discoideum ◽  
Early Development ◽  
Normal Development ◽  
Peptidase Activity ◽  
Fruiting Bodies ◽  
Wild Type ◽  
Formation Stage ◽  
Mitochondrial Processing Peptidase ◽  
Processing Peptidase

We investigated the expression of the α subunit of the Dictyostelium mitochondrial processing peptidase (Ddα-MPP) during development. Ddα-MPP mRNA is expressed at the highest levels in vegetatively growing cells and during early development, and is markedly downregulated after 10 h of development. The Ddα-MPP protein is expressed as two forms, designated α-MPPH and α-MPPL, throughout the Dictyostelium life cycle. The larger form, α-MPPH, is cleaved to produce the functional α-MPPL form. We were not able to isolate mutants in which the α-mpp gene had been disrupted. Instead, an antisense transformant, αA2, expressing α-MPP at a lower level than the wild-type AX-3 was isolated to examine the function of the α-MPP protein. Development of the αA2 strain was normal until the slug formation stage, but the slug stage was prolonged to ∼24 h. In this prolonged slug stage, only α-MPPH was present, and α-MPPL protein and MPP activity were not detected. After 28 h, α-MPPL and MPP activity reappeared, and normal fruiting bodies were formed after a delay of approximately 8 h compared with normal development. These results indicate that MPP activity is controlled by the processing of α-MPPH to α-MPPL during development in Dictyostelium.

scholarly journals A Putative Ariadne-Like Ubiquitin Ligase Is Required for Dictyostelium discoideum Development

2006 ◽  
Vol 5 (10) ◽  
pp. 1820-1825 ◽  
Author(s):  
Nathaniel Whitney ◽  
Lacey J. Pearson ◽  
Ryan Lunsford ◽  
Lisa McGill ◽  
Richard H. Gomer ◽  
...  
Keyword(s):  
Dictyostelium Discoideum ◽  
Ubiquitin Ligase ◽  
Fruiting Bodies ◽  
Wild Type ◽  
Cell Numbers

ABSTRACT The Dictyostelium rbrA gene encodes a putative Ariadne ubiquitin ligase. rbrA − cells form defective slugs that cannot phototax. Prestalk cell numbers are reduced in rbrA − slugs, and these prestalk cells do not localize to the tip of slugs. Chimeric slugs containing wild-type cells could phototax and form fruiting bodies.

Action of a slowly hydrolysable cyclic AMP analogue on developing cells of Dictyostelium discoideum

1979 ◽  
Vol 35 (1) ◽  
pp. 321-338
Author(s):  
C. Rossier ◽  
G. Gerisch ◽  
D. Malchow
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Type Strain ◽  
Wild Type Strain ◽  
Agar Plate ◽  
Cell Aggregation ◽  
Fruiting Bodies ◽  
Wild Type ◽  
Camp Analogue ◽  
Order Of Magnitude

Adenosine 3′,5′-cyclic phosphorothioate (cAMP-S) is a cyclic AMP (cAMP) analogue which is only slowly hydrolysed by phosphodiesterases of Dictyostelium discoideum. The affinity of cAMP-S to cAMP receptors at the cell surface is only one order of magnitude lower than that of cAMP. cAMP-S can replace cAMP as a stimulant with respect to all receptor-mediated responses tested, including chemotaxis and the induction of cAMP pulses. cAMP-S does not affect growth of D. discoideum but it blocks cell aggregation at a uniform concentration of 5 × 10(−7) M in agar plate cultures of strain NC-4 as well as its axenically growing derivative, Ax-2. Another wild-type strain of D. discoideum, v-12, is able to aggregate on agar plates supplemented with 1 mM cAMP-S. The development of Polysphondylium pallidum and P. violaceum is also highly cAMP-S resistant. In Ax-2 both differentiation from the growth phase to the aggregation-competent stage and chemotaxis are cAMP-S sensitive, whereas in v-12 only chemotaxis is inhibited. v-12 can still form streams of cohering cells and fruiting bodies when chemotaxis is inhibited by cAMP-S. Whereas cAMP induces differentiation into stalk cells at concentrations of 10(−3) or 10(−4) M, cAMP-S has the same effect in strain v-12 at the much lower concentration of 10(−6) M.

scholarly journals A Critical-like Collective State Leads to Long-range Cell Communication in Dictyostelium discoideum Aggregation

2016 ◽  
Author(s):  
Giovanna De Palo ◽  
Darvin Yi ◽  
Robert G. Endres
Keyword(s):  
Single Cell ◽  
Dictyostelium Discoideum ◽  
Long Range ◽  
Early Development ◽  
Cell Communication ◽  
Multiscale Model ◽  
Wild Type ◽  
Social Amoeba ◽  
Range Cell ◽  
Cell Cell

AbstractThe transition from single-cell to multicellular behavior is important in early development but rarely studied. The starvation-induced aggregation of the social amoeba Dictyostelium discoideum into a multicellular slug is known to result from single-cell chemotaxis towards emitted pulses of cyclic adenosine monophosphate (cAMP). However, how exactly do transient short-range chemical gradients lead to coherent collective movement at a macroscopic scale? Here, we developed a multiscale model verified by quantitative microscopy to describe wide-ranging behaviors from chemotaxis and excitability of individual cells to aggregation of thousands of cells. To better understand the mechanism of long-range cell-cell communication and hence aggregation, we analyzed cell-cell correlations, showing evidence of self-organization at the onset of aggregation (as opposed to following a leader cell). Surprisingly, cell collectives, despite their finite size, show features of criticality known from phase transitions in physical systems. By comparing wild-type and mutant cells with impaired aggregation, we found the longest cellcell communication distance in wild-type cells, suggesting that criticality provides an adaptive advantage and optimally sized aggregates for the dispersal of spores.Author SummaryCells are often coupled to each other in cell collectives, such as aggregates during early development, tissues in the developed organism, and tumors in disease. How do cells communicate over macroscopic distances much larger than the typical cell-cell distance to decide how they should behave? Here, we developed a multiscale model of social amoeba, spanning behavior from individuals to thousands of cells. We show that local cell-cell coupling via secreted chemicals may be tuned to a critical value, resulting in emergent long-range communication and heightened sensitivity. Hence, these aggregates are remarkably similar to bacterial biofilms and neuronal networks, all communicating in a pulse-like fashion. Similar organizing principles may also aid our understanding of the remarkable robustness in cancer development.

scholarly journals Characterization and Submitochondrial Localization of the α Subunit of the Mitochondrial Processing Peptidase from the Aquatic Fungus Blastocladiella emersonii

1999 ◽  
Vol 181 (14) ◽  
pp. 4257-4265 ◽  
Author(s):  
Cíntia Renata Costa Rocha ◽  
Suely Lopes Gomes
Keyword(s):  
Life Cycle ◽  
Molecular Mechanisms ◽  
Nucleotide Sequence Analysis ◽  
Aquatic Fungus ◽  
Western Blots ◽  
Α Subunit ◽  
Calculated Molecular Mass ◽  
Mitochondrial Processing Peptidase ◽  
Processing Peptidase ◽  
Blastocladiella Emersonii

ABSTRACT In an effort to investigate the molecular mechanisms responsible for the drastic morphological changes the mitochondria go through during the life cycle of the aquatic fungus Blastocladiella emersonii, the gene encoding the α subunit of the mitochondrial processing peptidase (α-MPP) was isolated. Nucleotide sequence analysis revealed that the predicted α-MPP polypeptide comprises 474 amino acids with a calculated molecular mass of 51,900 Da, presenting a characteristic mitochondrial signal sequence. Northern blot analysis indicated a single 1.4-kb transcript encoding the B. emersonii α-MPP, whose levels decrease during sporulation, becoming very low in the zoospore, and increase again during germination. Despite these variations in mRNA concentration, B. emersonii α-MPP protein levels do not change significantly during the life cycle of the fungus, as observed in Western blots. Experiments to investigate the submitochondrial localization ofB. emersonii α-MPP and β-MPP were also carried out, and the results indicated that both subunits are associated with the mitochondrial inner membrane, possibly as part of the bc1complex, as described for plants.

Cell sorting out during the differentiation of mixtures of metabolically distinct populations of Dictyostelium discoideum

Development ◽  
1973 ◽  
Vol 29 (3) ◽  
pp. 647-661
Author(s):  
C. K. Leach ◽  
J. M. Ashworth ◽  
D. R. Garrod
Keyword(s):  
Life Cycle ◽  
Dictyostelium Discoideum ◽  
Cell Sorting ◽  
Relative Number ◽  
Exponential Phase ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Axenic Medium ◽  
Spore Population ◽  
The Relationship

The behaviour, during the multicellular phase of the life-cycle, of amoebae of Dictyostelium discoideum grown in different media is described. Amoebal populations were marked by growth-temperature-sensitive genetic lesions which do not interfere with developmental phenomena. The fate of cell populations was determined by measuring the relative number of mutant and wild-type cells at various stages in the life-cycle. Cells sort out during development in such a way that they may be ordered in a sequence in which those given early in the following list preferentially appear in the spore population when mixed with those given later in the list: cells grown in axenic medium + 86 mm glucose and harvested when in the exponential phase of growth; cells grown in axenic medium and harvested when in the exponential phase of growth; cells grown on bacteria and harvested when in the exponential phase of growth; cells grown in axenic medium + 86 mM glucose and harvested when in the stationary phase of growth. Chemotactic aggregation and grex migration are not essential for sorting-out to occur but, in the normal life-cycle, the cells of a grex formed from amoebae grown in different media have sorted out anteroposteriorly. The relationship between this sorting out behaviour and the mechanism of pattern formation in fruiting-body morphogenesis is discussed. Differences in density of the amoebae cannot account for the sorting out predispositions we observe.

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 Inheritance of extrachromosomal ribosomal DNA during the asexual life cycle of Dictyostelium discoideum: examination by use of DNA polymorphisms.

1985 ◽  
Vol 5 (2) ◽  
pp. 273-280 ◽  
Author(s):  
D L Welker ◽  
K P Hirth ◽  
K L Williams
Keyword(s):  
Life Cycle ◽  
Dictyostelium Discoideum ◽  
Ribosomal Dna ◽  
Dna Polymorphisms ◽  
Haploid Cell ◽  
Wild Type ◽  
Parasexual Cycle ◽  
Restriction Fragments ◽  
Type Isolate ◽  
Ca 50

Wild-type isolates of Dictyostelium discoideum exhibited differences in the size of restriction fragments of the extrachromosomal 88-kilobase ribosomal DNA (rDNA) palindrome. Polymorphisms in rDNA also were found among strains derived solely from the NC4 wild-type isolate. These variations involved EcoRI fragments II, III, and V; they included loss of the EcoRI site separating fragments II and V and deletion and insertion of DNA. More than one rDNA form can coexist in the same diploid or haploid cell. However, one or another parental rDNA tended to predominate in diploids constructed, using the parasexual cycle, between haploid NC4-derived strains and haploid wild-type isolates. In some cases, most if not all of the rDNA of such diploids were of one form after ca. 50 generations of growth. Segregant haploids, derived from diploids that possessed predominantly a single rDNA allele, possessed the same allele as the diploid and did not recover the other form. This evidence implies that replication does not proceed from a single chromosomal or extrachromosomal copy of the rDNA during the asexual life cycle of D. discoideum.

The effect of chymotrypsin on the development of Dictyostelium discoideum

Development ◽  
1980 ◽  
Vol 57 (1) ◽  
pp. 189-201
Author(s):  
David C. Kilpatrick ◽  
Jerzy A. Schmidt ◽  
John L. Stirling ◽  
John Pacy ◽  
Gareth E. Jones
Keyword(s):  
Electron Microscopy ◽  
Dictyostelium Discoideum ◽  
Normal Development ◽  
Fruiting Bodies ◽  
Con A ◽  
Cellular Slime Mould ◽  
Slime Mould ◽  
Spore Walls ◽  
Cellular Slime ◽  
Vacuolated Cells

Development of the cellular slime mould Dictyostelium discoideum strain NC4, in the presence of α-chymotrypsin (3 mg/ml) is reversibly arrested at the tight aggregate stage (10/12 h). Pronase has a similar effect, but trypsin only retards normal development by about five hours. Normally developing cells are susceptible to α-chymotrypsin if they are transferred into its presence at any time up to the tight aggregate stage (10–12 h). Transfer after this stage does not affect the appearance of fruiting body structures in the normal time (24 h). Electron microscopy showed the ultrastructure of α-chymotrypsin-blocked aggregates after starvation for 24 h to be consistent with a block at 10–12 h of normal development. Poorly developed prespore vacuoles, having thin incomplete walls and a paucity of electrondense material, are present in some cells. No angular vacuolated cells characteristic of stalk cells are visible. Fruiting bodies formed in the presence of a α-chymotrypsin, either as minority structures when the enzyme is added before 10–12 h of normal development, or as the majority structures on later enzyme addition, were found to be abnormal. Normal stalks were formed but the spores were immature. Prespore vacuoles were present, though disrupted, and the cells were not encapsulated by spore walls. The electronegativity of intact slime mould amoebae was significantly reduced, and material containing L-[6-3H]-fucose and [l-14C]leucine was removed from the cell surface on α-chymotrypsin treatment. Few plasma membrane proteins were affected, however, and staining of polyacrylamide gels for glycopeptides using Con A-peroxide binding also showed little change.

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.

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