Repression of rRNA synthesis induced by disaggregation in Dictyostelium discoideum

Uchiyama, Saburo; Okamoto, Koji; Takeuchi, Ikuo

doi:10.1016/0005-2787(79)90130-8

Cited by 14 publications

(10 citation statements)

References 22 publications

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“…We have previously shown that disaggregation of Dictyostelium discoideum slugs induces repression of rRNA synthesis [18]. In the present study, it was found that the addition of 1 mM cAMP to disaggregated cells had no suppressive effect on the repression of rRNA synthesis, despite the fact that cAMP is known to suppress many disaggregation-induced metabolic changes in this organism.…”

Section: Discussioncontrasting

confidence: 51%

“…discoideum strain NC-4 was used. Procedures for cell growth, slug disaggregation, and RNA extraction are described in [18]. Labeling of cells was conducted in a liquid culture containing 5 p, Ci/ml [5-3H]uracil (30.1 Ci/mmol NEN) in the presence or absence of 1 mM cAMP (Sigma).…”

Section: Methodsmentioning

confidence: 99%

“…Our previous work showed that disaggregation of slugs induces the repression of rRNA synthesis, whether or not disaggregated cells are allowed to reaggregate afterwards [18]. Although rRNA constitutes the major part of total cellular RNA in general, the mechanism of its regulation in eukaryotic cells is almost totally unknown.…”

Section: Introductionmentioning

confidence: 99%

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Cyclic AMP fails to suppress disaggregation-induced repression of rRNA synthesis in Dictyostelium discoideum

Uchiyama

1987

FEMS Microbiology Letters

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Section: Discussioncontrasting

confidence: 51%

Section: Methodsmentioning

confidence: 99%

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Cyclic AMP fails to suppress disaggregation-induced repression of rRNA synthesis in Dictyostelium discoideum

Uchiyama

1987

FEMS Microbiology Letters

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“…The cells were grown in a liquid medium that contained the following per liter: 10 g bacto-peptone (Difco, Detroit, U.S.A.), 10g glucose, 0.96g Na2HPO4-12H2O, and 1.45 g KH2PO4 (22). Escherichia coli strain B/r was the food source for the myxoamoebae.…”

Section: Methodsmentioning

confidence: 99%

Fluorescence in the Migrating Pseudoplasmodium of the Cellular Slime Mold Dictyostelium mucoroides.

Uchiyama

Nagai

Maruyama

1994

Cell Struct. Funct.

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ABSTRACT. Fluorescence was observed under light microscope in living cells and cell mass of Dictyostelium mucoroides. The fluorescence was localized in the vacuoles of live vegetative cells. While the cell mass of D. discoideum does not have a stalk during migration period, the cell mass of D. mucoroides has a stalk that forms at the beginning of the migration period. Wewere able to observe a preferential loss of the fluorescent vacuoles from the cells of the stalk and from the stalk-forming cells at the tip region of the slug. Although the fluorescence was also present in the mature spore mass of Z>. mucoroides, the fluorescence was not observed in the spores, but rather in the spaces between the spores within the spore mass. The fluorescent vacuoles in the cells of vegetative stage and of migrating slug stage may be related to the interspore fluorescence in the spore mass. Possible roles of the fluorescent substance(s) in amoebae, slugs and spore masses were discussed.Amoebaeof the cellular slime mold Dictyostelium mucoroides proliferate by binary fission, using bacteria as a food source. After deprivation of bacteria, the homogeneouspopulation of slime mold cells aggregates to form a slug-shaped mass of cells (pseudoplasmodium) on a solid substratum. The cell mass ofD. mucoroides has a stalk that forms at the beginning of the migration period, during which time the cell mass crawls over the surface of the substratum. Eventually the mass of cells generates a fruiting body, which consists of a mass of spores and a supporting cellular stalk. The cells grown in liquid nutrient mediumremain stable for an extended period of time prior to cell lysis (18). This period is referred to as the stationary phase.

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“…Cells of the cellular slime mold, Dictyostelium discoideum strains NC4 and Ax2, and Dictyostelium mucoroides, were grown for 48 h at 22 qC with Escherichia coli B/r as the source of food for the myxamoebae in a suspension culture that contained bacto-peptone, glucose, Na 2 HPO 4 and KH 2 PO 4 (UCHIYAMA et al 1979). Cells were harvested by centrifugation and washed three times to free them from bacteria with BONNER's salt solution that contained NaCl, KCl and CaCl 2 (BONNER 1947).…”

Section: Preparation Of Cells and The Cell-free Crude Extractmentioning

confidence: 99%

Intracellular ribonuclease isozyme activity of the cellular slime mold cells,Dictyostelium discoideum Ax2 andDictyostelium mucoroides

Uchiyama

Nagai

Inokuchi

et al. 1999

J. Basic Microbiol.

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The isozymes of ribonuclease were analyzed in cell‐free, crude extracts of cells by reversed activity staining of polyacrylamide gradient gels after electrophoresis. We previously reported three isozymes of the intracellular ribonuclease in Dictyostelium discoideum NC4, which were found in vegetative cells. In the present study, we examined the ribonucleolytic activity of an axenic strain of D. discoideum Ax2 cells which can grow with or without bacteria. The mobility of these isozymes (Dd I, II and III) was the same regardless of the difference in the feeding condition. We also found the three isozymes of D. mucoroides cells, Dm I, II and III. Dm I was different from Dd I in D. discoideum cells, while Dm II and Dm III were the same as Dd II and Dd III in terms of the mobility in polyacrylamide gradient gels during electrophoresis.

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Repression of rRNA synthesis induced by disaggregation in Dictyostelium discoideum

Cited by 14 publications

References 22 publications

Cyclic AMP fails to suppress disaggregation-induced repression of rRNA synthesis in Dictyostelium discoideum

Cyclic AMP fails to suppress disaggregation-induced repression of rRNA synthesis in Dictyostelium discoideum

Fluorescence in the Migrating Pseudoplasmodium of the Cellular Slime Mold Dictyostelium mucoroides.

Intracellular ribonuclease isozyme activity of the cellular slime mold cells,Dictyostelium discoideum Ax2 andDictyostelium mucoroides

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