In vitro DNA fragmentation of mitochondrial DNA caused by single-stranded breakage related to macroplasmodial senescence of the true slime mold, Physarum polycephalum

2000 ◽  
Vol 37 (2) ◽  
pp. 125-135 ◽  
Author(s):  
Takashi Abe ◽  
Hiroyoshi Takano ◽  
Narie Sasaki ◽  
Kimie Mori ◽  
Shigeyuki Kawano
Keyword(s):  
Mitochondrial Dna ◽  
Dna Fragmentation ◽  
Physarum Polycephalum ◽  
Slime Mold

scholarly journals Non-DNA-Templated Addition of Nucleotides to the 3′ End of RNAs by the Mitochondrial RNA Polymerase of Physarum polycephalum

2008 ◽  
Vol 28 (18) ◽  
pp. 5795-5802 ◽  
Author(s):  
Mara L. Miller ◽  
Dennis L. Miller
Keyword(s):  
Mitochondrial Dna ◽  
Rna Polymerase ◽  
Rna Editing ◽  
Physarum Polycephalum ◽  
Mitochondrial Gene ◽  
In Vitro Transcription ◽  
Open Reading Frames ◽  
Mitochondrial Rna ◽  
Mitochondrial Rna Polymerase

ABSTRACT Mitochondrial gene expression is necessary for proper mitochondrial biogenesis. Genes on the mitochondrial DNA are transcribed by a dedicated mitochondrial RNA polymerase (mtRNAP) that is encoded in the nucleus and imported into mitochondria. In the myxomycete Physarum polycephalum, nucleotides that are not specified by the mitochondrial DNA templates are inserted into some RNAs, a process called RNA editing. This is an essential step in the expression of these RNAs, as the insertion of the nontemplated nucleotides creates open reading frames for the production of proteins from mRNAs or produces required secondary structure in rRNAs and tRNAs. The nontemplated nucleotide is added to the 3′ end of the RNA as the RNA is being synthesized during mitochondrial transcription. Because RNA editing is cotranscriptional, the mtRNAP is implicated in RNA editing as well as transcription. We have cloned the cDNA for the mtRNAP of Physarum and have expressed the mtRNAP in Escherichia coli. We have used in vitro transcription assays based on the Physarum mtRNAP to identify a novel activity associated with the mtRNAP in which non-DNA-templated nucleotides are added to the 3′ end of RNAs. Any of the four ribonucleoside triphosphates (rNTPs) can act as precursors for this process, and this novel activity is observed when only one rNTP is supplied, a condition under which transcription does not occur. The implications of this activity for the mechanism of RNA editing are discussed.

scholarly journals Emission and biosynthesis of volatile terpenoids from the plasmodial slime mold Physarum polycephalum

2019 ◽  
Vol 15 ◽  
pp. 2872-2880
Author(s):  
Xinlu Chen ◽  
Tobias G Köllner ◽  
Wangdan Xiong ◽  
Guo Wei ◽  
Feng Chen
Keyword(s):  
Physarum Polycephalum ◽  
Slime Mold ◽  
Terpene Biosynthesis ◽  
Terpene Synthases ◽  
Slime Molds ◽  
Geranyl Diphosphate ◽  
Monoterpene Synthase ◽  
Cellular Slime ◽  
Volatile Terpenoids

Terpene synthases (TPSs) are pivotal enzymes for the production of diverse terpenes, including monoterpenes, sesquiterpenes, and diterpenes. In our recent studies, dictyostelid social amoebae, also known as cellular slime molds, were found to contain TPS genes for making volatile terpenes. For comparison, here we investigated Physarum polycephalum, a plasmodial slime mold also known as acellular amoeba. Plasmodia of P. polycephalum grown on agar plates were found to release a mixture of volatile terpenoids consisting of four major sesquiterpenes (α-muurolene, (E)-β-caryophyllene, two unidentified sesquiterpenoids) and the monoterpene linalool. There were no qualitative differences in terpenoid composition at two stages of young plasmodia. To understand terpene biosynthesis, we analyzed the transcriptome and genome sequences of P. polycephalum and identified four TPS genes designated PpolyTPS1–PpolyTPS4. They share 28–73% of sequence identities. Full-length cDNAs for the four TPS genes were cloned and expressed in Escherichia coli to produce recombinant proteins, which were tested for sesquiterpene synthase and monoterpene synthase activities. While neither PpolyTPS2 nor PpolyTPS3 was active, PpolyTPS1 and PpolyTPS4 were able to produce sesquiterpenes and monoterpenes from the respective substrates farnesyl diphosphate and geranyl diphosphate. By comparing the volatile profile of P. polycephalum plasmodia and the in vitro products of PpolyTPS1 and PpolyTPS4, it was concluded that most sesquiterpenoids emitted from P. polycephalum were attributed to PpolyTPS4. Phylogenetic analysis placed the four PpolyTPSs genes into two groups: PpolyTPS1 and PpolyTPS4 being one group that was clustered with the TPSs from the dictyostelid social amoeba and PpolyTPS2 and PpolyTPS3 being the other group that showed closer relatedness to bacterial TPSs. The biological role of the volatile terpenoids produced by the plasmodia of P. polycephalum is discussed.

scholarly journals Ras protein of the slime mold Physarum polycephalum is farnesylated in vitro.

1999 ◽  
Vol 46 (3) ◽  
pp. 771-775
Author(s):  
E Talarczyk ◽  
V S Hung ◽  
P Kozlowski ◽  
J Trzcinska-Danielewicz ◽  
E Swiezewska
Keyword(s):  
Physarum Polycephalum ◽  
Slime Mold ◽  
Terminal Sequence ◽  
Ras Protein

Physarum Ppras1 protein was efficiently prenylated by prenyltransferases of spinach. Surprisingly in spite of the C-terminal sequence (CLLL) specific for geranylgeranylation the protein was preferentially farnesylated. Consequences of this observation are discussed.

Ca-Histochemistry in slime mold plasmodia

1978 ◽  
Vol 36 (2) ◽  
pp. 130-131
Author(s):  
Ulrich Dierkes
Keyword(s):  
Physarum Polycephalum ◽  
Carbon Coating ◽  
Freeze Drying ◽  
Freeze Fracture ◽  
Freeze Substitution ◽  
Uranyl Acetate ◽  
Slime Mold ◽  
Staining Procedure ◽  
Protoplasmic Streaming ◽  
Intracellular Ca

Calcium is supposed to play an important role in the control of protoplasmic streaming in slime mold plasmodia. The motive force for protoplasmic streaming is generated by the interaction of actin and myosin. This contraction is supposed to be controlled by intracellular Ca-fluxes similar to the triggering system in skeleton muscle. The histochemical localisation of calcium however is problematic because of the possible diffusion artifacts especially in aquous media.To evaluate this problem calcium localisation was studied in small pieces of shock frozen (liquid propane at -189°C) plasmodial strands of Physarum polycephalum, which were further processed with 3 different methods: 1) freeze substitution in ethanol at -75°C, staining in 100% ethanol with 1% uranyl acetate, and embedding in styrene-methacrylate. For comparison the staining procedure was omitted in some preparations. 2)Freeze drying at about -95°C, followed by immersion with 100% ethanol containing 1% uranyl acetate, and embedding. 3) Freeze fracture, carbon coating and SEM investigation at temperatures below -100° C.

Characterization of a Motile Cellular Domain Arising During the Amoebo-Flagellate Transformation of Physarum Polycephalum

1980 ◽  
Vol 38 ◽  
pp. 552-553
Author(s):  
K.I. Pagh ◽  
M.R. Adelman
Keyword(s):  
Cell Shape ◽  
Physarum Polycephalum ◽  
Slime Mold ◽  
Live Cells ◽  
Cellular Domain

Unicellular amoebae of the slime mold Physarum polycephalum undergo marked changes in cell shape and motility during their conversion into flagellate swimming cells (l). To understand the processes underlying motile activities expressed during the amoebo-flagellate transformation, we have undertaken detailed investigations of the organization, formation and functions of subcellular structures or domains of the cell which are hypothesized to play a role in movement. One focus of our studies is on a structure, termed the “ridge” which appears as a flattened extension of the periphery along the length of transforming cells (Fig. 1). Observations of live cells using Nomarski optics reveal two types of movement in this region:propagation of undulations along the length of the ridge and formation and retraction of filopodial projections from its edge. The differing activities appear to be associated with two characteristic morphologies, illustrated in Fig. 1.

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