High-density induction of a quiescent cell state in Physarum polycephalum

1977 ◽  
Vol 25 (1) ◽  
pp. 179-190
Author(s):  
L.E. McAlister ◽  
V.F. Allison ◽  
J.R. Jeter ◽  
C. Nations
Keyword(s):  
Physarum Polycephalum ◽  
Rna Synthesis ◽  
High Density ◽  
Mitochondrial Morphology ◽  
Nuclear Actin ◽  
Active Growth ◽  
Cell State ◽  
Cytoplasmic Organization ◽  
Protein Complement ◽  
Proliferative Cell

The non-histone protein complement of Physarum polycephalum changes rapidly when microplasmodia are subjected to conditions of high density. The changes in these proteins induced by high density are similar to the changes observed during starvation-induced encystment. A 50% decrease in DNA synthesis, observed after 7 h of starvation, is observed after only 1 h of high density. High density also results in a decrease in RNA synthesis comparable to decreases induced by prolonged starvation. Total heterochromatin increases in response to either high density or starvation. Increased heterochromatization is preceded by an increase in nuclear actin. Mitochondrial morphology and cytoplasmic organization are also similarly altered by starvation and high density. These observations suggest the possibility of a generalized mechanism for cellular transition from active growth to a non-proliferative cell state.

Effects of cordycepin on RNA synthesis in Physarum polycephalum

1975 ◽  
Vol 168 (1) ◽  
pp. 273-280 ◽  
Author(s):  
H. Fouquet ◽  
R. Wick ◽  
R. Böhme ◽  
H.W. Sauer ◽  
K. Scheller
Keyword(s):  
Physarum Polycephalum ◽  
Rna Synthesis

In vitro transcription of RNA in nuclei, nucleoli and chromatin from physarum polycephalum

1977 ◽  
Vol 26 (1) ◽  
pp. 267-279
Author(s):  
K.E. Davies ◽  
I.O. Walker
Keyword(s):  
Rna Polymerase ◽  
Physarum Polycephalum ◽  
Rna Synthesis ◽  
In Vitro Transcription ◽  
Polymerase Activity ◽  
Controlled Conditions ◽  
Rna Polymerase Activity ◽  
Alpha Amanitin

Methods for isolating nuclei, nucleoli and chromatin from Physarum polycephalum which retain high levels of endogenous RNA polymerase activity are described. Under carefully controlled conditions with respect to mono- and divalent cation concentrations RNA synthesis in nuclei displayed linear kinetics for at least 30 min and the RNA products had a similar size distribution to nuclear RNA synthesis observed in vivo. Chromatin showed 60% of the nuclear transcriptional activity but no conditions were found where faithful transcription of the template occurred. Isolated nucleoli were 5-fold more active than nuclei and the endogenous RNA polymerase activity was insensitive to alpha-amanitin. Under carefully controlled conditions, the nucleoli appeared to support the accurate transcription, re-initiation and processing of rRNA chains in vitro.

Some evidence for replication-transcription coupling in Physarum polycephalum

1975 ◽  
Vol 18 (1) ◽  
pp. 27-39
Author(s):  
H. Fouquet ◽  
R. Bohme ◽  
R. Wick ◽  
H.W. Sauer ◽  
K. Scheller
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Dna Sequences ◽  
Physarum Polycephalum ◽  
Rna Synthesis ◽  
Selective Inhibition ◽  
S Phase ◽  
Dna Molecules ◽  
Uridine Incorporation ◽  
G2 Phase

Hydroxyurea, at concentrations of 40–60 mM, selectively and effectively blocked incorporation of thymidine into DNA. Inhibition occurred within 5–10 min of application of the agent when DNA synthesis was in progress, while the onset of replication at the beginning of S-phase and DNA synthesis in G2 phase were not affected. Uridine incorporation into TCA-precipitable material, in the presence of hydroxyurea, was significantly (up to 70%) inhibited in early S-phase of the cell cycle. Selective inhibition of RNA synthesis was confirmed for RNA separated into rRNA-rich and poly(A)-rich RNA fractions and analysed by the 2 kinds of DNA-RNA hybridization reactions. Uridine incorporation into poly (A) RNA was also inhibited under conditions where cycloheximide prevented maturation of nascent DNA molecules in early S-phase. We assume that chromatin which is replicating early DNA sequences may be a more competent template for transcription.

scholarly journals ON ELECTRICAL CORRELATES OF PHYSARUM POLYCEPHALUM SPATIAL ACTIVITY: CAN WE SEE PHYSARUM MACHINE IN THE DARK?

2011 ◽  
Vol 06 (01n02) ◽  
pp. 29-57 ◽  
Author(s):  
ANDREW ADAMATZKY ◽  
JEFF JONES
Keyword(s):  
Physarum Polycephalum ◽  
Local Population ◽  
Dynamical Behavior ◽  
Electrical Potential ◽  
Low Frequency ◽  
Electric Activity ◽  
Growth Zone ◽  
Oscillatory Behavior ◽  
Active Growth ◽  
A Site

Plasmodium of Physarum polycephalum is a single cell visible by unaided eye, which spans sources of nutrients with its protoplasmic network. In a very simple experimental setup we recorded electric potential of the propagating plasmodium. We discovered a complex interplay of short range oscillatory behavior combined with long range, low frequency oscillations which serve to communicate information between different parts of the plasmodium. The plasmodium's response to changing environmental conditions forms basis patterns of electric activity, which are unique indicators of the following events: plasmodium occupies a site, plasmodium functions normally, plasmodium becomes "agitated" due to drying substrate, plasmodium departs a site, and plasmodium forms sclerotium. Using a collective particle approximation of Physarum polycephalum we found matching correlates of electrical potential in computational simulations by measuring local population flux at the node positions, generating trains of high and low frequency oscillatory behavior. Motifs present in these measurements matched the response "grammar" of the plasmodium when encountering new nodes, simulated consumption of nutrients, exposure to simulated hazardous illumination and sclerotium formation. The distributed computation of the particle collective was able to calculate beneficial network structures and sclerotium position by shifting the active growth zone of the simulated plasmodium. The results show future promise for the non-invasive study of the complex dynamical behavior within — and health status of — living systems.

Polyphosphate in the life cycle of Physarum polycephalum and its relation to RNA synthesis

1969 ◽  
Vol 195 (2) ◽  
pp. 401-409 ◽  
Author(s):  
H.W. Sauer ◽  
E.M. Goodman ◽  
K.L. Babcock ◽  
H.P. Rusch
Keyword(s):  
Life Cycle ◽  
Physarum Polycephalum ◽  
Rna Synthesis

Cytochemical study of nucleolar structure and formation in physarum polycephalum

1978 ◽  
Vol 36 (2) ◽  
pp. 214-215
Author(s):  
J.G. Lafontaine ◽  
M. Cadrin
Keyword(s):  
Physarum Polycephalum ◽  
Rna Synthesis ◽  
Tritiated Thymidine ◽  
Culture Conditions ◽  
Mitotic Chromosomes ◽  
Cytochemical Study ◽  
Nucleolar Structure ◽  
Dna And Rna ◽  
Dna And Rna Synthesis ◽  
Perfect Synchrony

Under appropriate culture conditions the slime mold, Physarum polycephalum, can be grown in the form of multinucleated plasmodia. In view of the fact that these numerous nuclei divide in perfect synchrony, this organism offers unique advantages for studying different aspects of the cell cycle.As in other organisms studied so far, the interphase nucleolus consists of fibrillar regions surrounded by conspicuous granular zones. These fibrillar regions, however, are spherical in shape and are characterized by the presence of opaque particles. As the nucleolar mass disorganizes these spherical nucleolar portions persist in the form of bodies which migrate with the mitotic chromosomes to the nuclear poles. Prelabeling of G2 nuclei with tritiated thymidine permits to demonstrate that these nucleolar remnants contain DNA and that this DNA is still present within their mass as they become integrated within the early interphase daughter nuclei. Since the G1 period is lacking in this organism, both DNA and RNA synthesis are resumed soon after mitosis: the nucleus increases in size and the nucleolus is also reformed quite rap idly.

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