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high diadenosine tetraphosphate (ap4a) level at initiation of s phase in the naturally synchronous mitotic cycle of physarum polycephalum.levels of the diadenosine tetraphosphate ap4a are high during exponential growth of physarum, decrease during encystment (spherulation) and increase again during excystment. consistently, a rapid 8-30-fold increase in ap4a level occurs at entry into s phase of the mitotic cycle and is maintained during the first half of genome replication. the elevated ap4a level depends significantly on ongoing dna replication and is completely sensitive to the protein synthesis inhibitor cycloheximide administ ...19846489457
phase-dependent polymerization and depolymerization of actin in physarum polycephalum nuclei.g- and f-actin contents in physarum polycephalum nuclei isolated during the progress of cell cycle were estimated and compared both by the inhibiting activity of deoxyribonuclease i (dnase i) and by the fractionation on deae-toyopearl column chromatography. the inhibition of dnase appeared maximal in late s phase or early g2 phase and decreased to a minimal value in late g2 phase or m phase, while total actin content in a nucleus, which was analyzed by sds-polyacrylamide gel electrophoresis as w ...19846498942
atp- and calcium-controlled contraction in a saponin model of physarum polycephalum.saponin models of the plasmodial strand of physarum polycephalum were constructed to study how ca2+ and atp regulate the generation of tension. atp-induced isometric tension in a saponin model increased with an increase in atp concentration until maximum tension (0.3-1.7 mg) was reached at about 1 mm. the sensitivity of the model to atp was heightened three to five times in a basic solution containing an atp-regenerating system, the maximum tension (0.3-0.6 mg) being reached at 0.2 to 0.3 mm atp ...19846498946
[study of the effect of different concentrations of a detergent on the chromatin structure of physarum polycephalum during the mitotic cycle].the influence of different concentrations of detergent joy on the chromatin structure of physarum polycephalum in the process of mitotic cycle was studied electronmicroscopically. the investigations showed that at joy concentrations less than 0,01% a small part of nuclei disrupt and, as a rule, chromatin is insufficiently dispersed; at concentrations more than 0,1% the detergent may influence the chromatin structure of physarum polycephalum. based on the data obtained we consider that the optima ...19846521732
a mathematically modelled cytogel cortex exhibits periodic ca++-modulated contraction cycles seen in physarum shuttle streaming.if each of many cells of an embryo (or different zones in a single cell) possess identical active cytogel machinery, having the 'right' mechanochemical response properties, then the collective interaction among those identical participants leads automatically to the globally coherent tissue deformations seen in embryogenesis, and to shuttle streaming in the plasmodial slime mould physarum polycephalum. biologically plausible, and experimentally verifiable hypotheses are proposed concerning how t ...19846533241
induction of polyploid nuclei in the plasmodium of physarum polycephalum by platinum antitumor compounds.the intranuclear mitosis of the plasmodial nuclei of myxomycetes permits the observation of defects in chromosomal repartition which would probably be lethal in other eukaryotic cells with open mitosis. we found that antitumoral platinum-amine compounds perturbed late mitotic events and induced the formation of giant nuclei which were polyploid in plasmodia of physarum polycephalum. using 26 platinum-amine complexes, we have shown that all antitumoral compounds induced the formation of polyploid ...19846537900
analysis of an inducer of the amoebal-plasmodial transition in the myxomycetes didymium iridis and physarum polycephalum.recent studies with amoebae of the myxomycetes didymium iridis and physarum polycephalum reveal that competence to undergo sexual fusion or to differentiate to plasmodia apogamically can be induced by a diffusible factor. suspension cultures of didymium amoebae have proven to be a good source of the inducer activity. cell-free culture supernatants accelerated mating of didymium and physarum amoebae and also apogamic differentiation of the physarum strain colonia . characterization and purificati ...19846539260
mechanics of cytogels i: oscillations in physarum.the contractility of actomyosin gels is the basis for a variety of cellular motility phenomena. we present here a mechanical analysis of contractile gels. by making certain hypotheses on the chemical regulation of cytogel contraction we formulate a model for the rhythmic contractions of plasmodia in the slime mold physarum polycephalum which is in accord with a number of experimental observations.19846542453
reactivation of nbd-phallacidin-labelled actomyosin fibrils in cryosections of physarum polycephalum: a new cell-free model.application of atp to cryosections of plasmodial strands from physarum polycephalum leads to an isotonic contraction of the cytoplasmic actomyosin fibrils: when the fibrils are labelled with nbd-phallacidin, their contraction can be observed in the fluorescence microscope. while performing contraction, the fibrils separate into many small units and the formerly continuous fibrils exhibit the appearance of beaded chains. the possibility of visualizing directly the contraction of cytoplasmic actom ...19846542827
cross-reactions of polysaccharides of fungi, molds, and yeasts in anti-pneumococcal and other antisera.cross-reactions of a number of glycans and polysaccharides isolated from fungi, molds, and yeasts in anti-pneumococcal and other antisera are tabulated and discussed insofar as possible with relation to the chemical structures of the cross-precipitating substances and the polysaccharidic antigens giving rise to the reactive antibodies. for example, the slime of physarum polycephalum precipitated antisera to pneumococcal type 4 and klebsiella type k1. the polysaccharides of type 4 and k1 contain ...19846591189
invariant temporal order of replication of the four actin gene loci during the naturally synchronous mitotic cycles of physarum polycephalum.the chronological sequence of replication for the four unlinked actin gene loci of physarum has been established. southern hybridization analysis of density-labeled, bromodeoxyuridine-substituted dna isolated from defined periods of s phase demonstrates that three actin loci (ardb, ardc, ardd) are duplicated early, corresponding to the first 10% of the genome. the fourth locus (arda) replicates later, between 80 and 100 min into s phase and after 75% of dna synthesis is completed. gene-dosage de ...19846593708
polyamine-stimulated alteration of the ornithine decarboxylase molecule in physarum polycephalum.the molecular mechanism for polyamine-stimulated feedback modification of ornithine decarboxylase isolated from physarum polycephalum was investigated by using two-dimensional polyacrylamide-gel electrophoresis. partially purified a-form enzyme was converted into the b-form enzyme by isolated fractions of the physarum a-b-converting protein, and the substrates and products were subsequently labelled by covalent addition of alpha-difluoro[14c]methylornithine, an enzyme-activated irreversible inhi ...19836615477
rheological properties of living cytoplasm: endoplasm of physarum plasmodium.magnetic sphere viscoelastometry, video microscopy, and the kamiya double chamber method (kamiya, n., 1940, science [wash. dc], 92:462-463.) have been combined in an optical and rheological investigation of the living endoplasm of physarum polycephalum. the rheological properties examined were yield stress, viscosity (as a function of shear), and elasticity. these parameters were evaluated in directions perpendicular; (x) and parallel (y) to the plasmodial vein. known magnetic forces were used f ...19836619187
ornithine decarboxylase and the ornithine decarboxylase-modifying protein of physarum polycephalum. 19836621381
polyamine-dependent protein kinase from the slime mold physarum polycephalum. 19836621382
lack of correlation between histone h4 acetylation and transcription during the physarum cell cycle.the interaction between nucleosomal proteins and dna is expected to change during dna replication as well as during transcription. a possible way of achieving the necessary structural changes is the modification of histones and high mobility group (hmg) proteins. the acetylation of core histones has been studied in various systems (for a review see ref. 1) and a correlation between histone acetylation and transcriptional activity of chromatin has frequently been proposed. in particular, bradbury ...19836621695
acetylation and methylation sites in histone h4 from physarum polycephalum.histone h4 has been isolated and purified from plasmodia of physarum polycephalum. the four major fragments produced by hydrolysis of h4 by acetic acid were separated and the complete amino acid sequence of two of them was determined. by analogy with calf h4, these peptides are at the c-terminus and give the sequence from residue 68 to the c-terminus (residue 102). in this 35 residue sequence there are two minor differences from calf h4: (i) residue 77 is arginine in physarum h4 and lysine in ca ...19836628379
plasmodium formation in physarum polycephalum: cytological events and their timing relative to commitment.amoebae of "selfing" strains of physarum polycephalum transform into multinucleate plasmodia without change in ploidy. the transformation occurs when cultures of amoebae reach sufficiently high cell densities or when cultures of low densities are exposed through filters to dense "inducing" cultures of amoebae. we have induced selfing amoebae to transform individually and in populations in order to study cytological changes and their timing relative to the irreversible commitment of cells to plas ...19836640677
consequences of impeding in mitochondrial function in physarum polycephalum. ii. influence on "de novo" generation of contractile activities and responses to glucose and blue light.the "de novo" generation of longitudinal contractile activity in endoplasmic veins is inhibited by 5 mm kcn, whereas 10 mm alpha-ketoglutarate combined with 5 mm amp abolishes this inhibiting effect in spite of a continued presence of kcn. an analysis of the young's modulus and studies on the morphogenesis of endoplasmic veins reveal morphological effects of an impediment of cell respiration: (1) an increased fibrillogenesis and changes in the spatial distribution of cytoplasmic actomyosin fibri ...19836641734
correlation between torsion and streaming in physarum.experiments are described which show that the torsional oscillations arising in a strand of the slime mould, physarum polycephalum, under certain conditions remain closely correlated to oscillations in cytoplasmic streaming. when this is the case, the direction of rotation is related to the direction of streaming by a left-hand rule.19836641800
mitotic cell cycle control in physarum. unprecedented insights via flow-cytometry.high resolution flow-cytometric studies of isolated macroplasmodial nuclei of the myxomycete. physarum polycephalum provide definite evidence for the persistence of natural synchrony at mitosis throughout the entire cell cycle, i.e. completely synchronous dna replication and traverse of g2. even if nuclei within a given macroplasmodium belong to two distinct genome size classes (mixoploidy), they cycle and traverse mitosis in strict synchrony. this cannot be explained by current models of regula ...19836641801
variance of ploidy in mitochondrial nucleus during spherulation in physarum polycephalum.in physarum polycephalum, microplasmodia differentiated into spherules when cultures were aged for 8-10 days. respiration rates of the microplasmodia decreased rapidly with ageing to a 90% decrease in oxygen consumption over 9 days. we studied this phenomena by isolating and characterizing mitochondria from microplasmodia and spherules at different stages of spherulation. oxygen uptake by the isolated mitochondria decreased with spherulation. morphological and biochemical analyses showed that mi ...19836641807
unstable activator models for size control of the cell cycle.the unstable activator model of wheals & silverman (1982) is extended to account for the delay of nuclear division in the acellular slime mold, physarum polycephalum, that is caused by pulse treatments with inhibitors of protein synthesis. the model is solved exactly to predict the delay as a function of the half-life of the activator. the wheals-silverman model is found to give results comparable, but not superior, to other unstable activator models of the cell cycle.19836645566
polyamine-dependent protein kinase and phosphorylation of ornithine decarboxylase in physarum polycephalum. 19836645977
sequence organisation in nuclear dna from physarum polycephalum. genomic organisation of dna segments containing foldback sequences.dna clones containing foldback sequences, derived from physarum polycephalum nuclear dna, can be classified according to their pattern of hybridisation to southern blots of genomic dna. one group of dna clones map to unique dna loci when used as a probe to restriction digests of physarum nuclear dna. these cloned segments appear to contain dispersed repetitive sequence elements located at many hundreds of sites in the genome. similar patterns of hybridisation are generated when these cloned dna ...19836652089
sequence organisation in nuclear dna from physarum polycephalum. arrangement of highly-repeated sequences.recombinant plasmids containing highly repetitive physarum dna segments were identified by colony hybridisation using a radioactively-labelled total physarum dna probe. a large number of these clones also hybridised to a foldback dna probe purified from physarum nuclear dna. the foldback dna probe was characterised by reassociation kinetic analysis. about one-half of this component was shown to consist of highly repeated sequences with a kinetic complexity of 1100 bp and an average repetition fr ...19836652090
an extraction resistant tensile protein in the protoplasmic matrix of physarum.a thorough extraction of plasmodia of physarum polycephalum by sequential treatment with 1% triton x-100, 0.6 m ki, 4% sds plus 7 m urea leaves behind an elastic cell ghost, which represents a cytoplasmic matrix protein arranged as a continuous network in all cell regions. the protein is present in the ectoplasm as well as in the endoplasm. the extraction-resistant ghosts reveal filaments 2-3 nm in diameter, perform a conspicuous volume condensation upon the addition of mm-concentrations of di- ...19836652691
change in phosphorylation of nucleolar proteins of physarum polycephalum during the cell cycle in vivo and in vitro.we compared the phosphorylation of nucleolar proteins during the cell cycle of physarum polycephalum labeled by pulse and continuous labeling methods in vivo with that obtained by in vitro labeling of isolated nucleoli. both the phosphorylating activity of nucleoli and total incorporation of radioactive phosphate into nucleolar proteins increased and reached a maximum about 1.5-2.0 h before mitosis, confirming our previous observation. analyses of labeled nucleolar proteins by sds-polyacrylamide ...19836654873
isolation and purification of transcriptionally active ribosomal chromatin from the slime mould, physarum polycephalum.in the acellular slime mold physarum polycephalum the ribosomal genes are all located on linear, extrachromosomal dna molecules which are clustered in the nucleolus. this report describes the isolation and purification of these ribosomal genes as functionally active chromatin particles. nucleolar lysates are fractionated by gel filtration to remove ribosomal precursors and other soluble material. the ribosomal chromatin is subsequently separated from contaminating nuclear chromatin by a sucrose ...19846696913
identification of tubulin isoforms in the plasmodium of physarum polycephalum by in vitro microtubule assembly.the tubulins of the plasmodium of physarum polycephalum have been identified by in vitro microtubule assembly from partially purified extracts of asynchronous microplasmodia and late g2 macroplasmodia. the plasmodial tubulin group comprised of 2 alpha tubulins (app. m.w. 51000 daltons) and 2 beta tubulins (app. m.w. 58000 daltons and 55000 daltons) and appeared to be identical with a group of polypeptides which are synthesized periodically in late g2. two of the plasmodial tubulin subunits (one ...19846698041
mitotic delays and macromolecular synthesis in g2 phase-irradiated plasmodia of physarum polycephalum.mitotically synchronous surface plasmodia of physarum polycephalum were irradiated at different times of g2 phase with doses of uv ranging from 350 to 2800 jm-2. the uv sensitivity, measured in terms of delay in progression towards mitosis, gradually declined through g2 phase to almost zero in early prophase, when irradiated with 350 jm-2 of uv. however, with higher doses, 700 and 1400 jm-2, late g2 was found to be even more susceptible than early g2. the delay in these cases rises for the last ...19846698113
purification and properties of ornithine decarboxylase from physarum polycephalum.ornithine decarboxylase (ec 4.1.1.17) has been purified 3,500-fold from the plasmodia of physarum polycephalum. the purified material exhibited a km for ornithine of 0.6 mm and vmax of 20 mumol of co2 formed per min/mg at 30 degrees c (62 mumol/min/mg at 37 degrees c). it migrated as a single protein and activity species on high pressure liquid chromatography (tsk-3000) in 0.15 m nacl (mr = 80,000) and in native gels containing 5, 6.5, 8, and 9.5% acrylamide. a single protein band (mr = 43,000) ...19846706929
isolation and characterization of a high molecular weight actin-binding protein from physarum polycephalum plasmodia.a high molecular weight actin-binding protein was isolated from the physarum polycephalum plasmodia. the protein ( hmwp ) shares many properties with other high molecular weight actin-binding proteins such as spectrin, actin-binding protein from macrophages, and filamin. it has a potent activity to cross-link f-actin into a gel-like structure. its cross-linking activity does not depend on calcium concentrations. hydrodynamic studies have revealed that the protein is in the monomeric state of a p ...19846725393
separation of histones from physarum polycephalum by ion-paired, reverse-phase high-performance liquid chromatography.the histones of physarum polycephalum were efficiently separated using a mubondapak c-18 column with 50 mm triethylamine-phosphoric acid, ph 2.2, as the aqueous phase and a gradient of increasing concentration of acetonitrile. the effects of buffer concentration and changes in gradient rate and flow rate on retention times were investigated to optimize separation. the recovery of total histones (70%) was independent of loading up to at least 0.5 mg. loading had little effect on retention times. ...19846731840
the isolation of nuclei containing mitotic spindles from the plasmodium of the slime mould physarum polycephalum.we have developed a protocol which facilitates the isolation of nuclei containing mitotic spindles from the plasmodium of physarum polycephalum. the nuclei are isolated in a spindle stabilization buffer (ssb) consisting of -4 m glycerol, 5 mm egta, 10 mm mgcl2, 10 mm pipes and 0.1% (v/v) triton x-100 at ph 6.5. isolation at 20 degrees c, chelation of ca2+ and the inclusion of the 4 m glycerol were found to be essential for stabilization of the spindle microtubules. the method allows the isolatio ...19846734631
induction of polyploid nuclei in physarum polycephalum by cycloheximide treatment in prophase.macroplasmodia of the acellular slime mold physarum polycephalum were treated with pulses of cycloheximide (10 micrograms/ml medium, for 3 h), initiated 10-20 min before metaphase in the synchronous nuclear division cycle. this treatment interfered with normal division of the nuclei, but permitted dna synthesis in the next s phase. this interpretation is supported by measurements of the dna content per nucleus in cycloheximide-treated cultures as compared to control cultures, which show that som ...19846734762
thymidine kinase. a novel affinity chromatography of the enzyme and its regulation by phosphorylation in physarum polycephalum.dthd bound to epoxy-activated sepharose results in a high specific affinity adsorbent, which was used to purify physarum dthd kinase 8000-fold. with this purified enzyme, it was proved that dthd kinase exists in five enzyme variants in physarum polycephalum, the acidic forms being phosphorylated. this protein modification is discussed under the aspect of the regulation of this enzyme.19846736030
patterns of histone acetylation in physarum polycephalum. h2a and h2b acetylation is functionally distinct from h3 and h4 acetylation.histone acetylation has previously been correlated with both chromosome replication and transcription. we present evidence that (a) confirms both correlations in the true slime mold, physarum polycephalum and (b) shows that quite a different pattern of acetate turnover is associated with replication compared with transcription. the pattern associated with replication involves turnover of acetate on all four core histones on species containing one or two acetates per molecule. this pattern was re ...19846745279
unusual polyamines in slime molds physarum polycephalum and dictyostelium discoideum.we analyzed the cellular contents of not only major polyamines but also minor polyamines in slime molds physarum polycephalum and dictyostelium discoideum. the presence of putrescine and spermidine in either plasmodia or myxamoebae of these molds as major polyamines was confirmed. in addition to these polyamines, appreciable amounts of 1,3-diaminopropane were detected in p. polycephalum and d. discoideum. cadaverine and sym-homospermidine were detected in p. polycephalum even when the slime mold ...19846746590
immunocytochemistry of the acellular slime mold physarum polycephalum. ii. spatial organization of cytoplasmic actin. 19826751827
transfer rna and ribosomal rna are synthesized from the same pyrimidine nucleotide pool.we have tested the hypothesis [wiegers, kramer, klapproth & hilz (1976) eur. j. biochem. 64. 535-540] that the synthesis of rrna in the nucleolus may have a partially independent supply of nucleoside triphosphates that is not completely suppressed when cells are supplied with exogenous nucleosides. for the slime mould, physarum polycephalum, and chinese hamster ovary cells in culture, the specific activities (3h/32p) of ump and cmp in trna, which is synthesised in the nucleoplasm, and rrna were ...19826760857
stage-specific antigens of physarum polycephalum. 19806769687
an improved method for the isolation of polysomes from synchronous macroplasmodia of physarum polycephalum. 19806770713
conversion of positive to negative chemotaxis by ca2+ ionophore treatment in plasmodium of physarum polycephalum.the plasmodium of physarum polycephalum was treated with ca2+ ionophores a23187 or x-537a, and the effects on the chemotactic and contractile activities were studied by applying a double-chamber method and an optical method. (1) at low ca2+ concentration, attractants (glucose, l-alanine) kh2po4) remained as attractants and induced a relaxation in the plasmodial strand. increase in the external ca2+ level caused a contraction of plasmodium with the same stimuli, and hence converted the attractant ...19806783083
modulation of the epsilon-(gamma-glutamic)lysine cross-link in cellular proteins. i. in vivo and in vitro studies.the epsilon-(gamma-glutamic)lysine cross-link content of intracellular proteins in a variety of cell types can be modulated in vivo by temperature changes and in vitro by treatment with mg2+/-atp and mg2+/-atp plus ca2+. virtually all the cross-links are found in the cytoskeletal and membrane components which are not solubilized by glycerol extraction. in the slime mold, physarum polycephalum, enzyme activities persist which bring about a decrease in cross-link content upon addition of mg2+/-atp ...19816786352
a comparison of the proteins of the amoebal and plasmodial phases of the slime mould, physarum polycephalum.1. the proteins of amoebae and plasmodia of strain cl of physarum polycephalum have been compared by two-dimensional gel electrophoresis. both forms of the organism were labelled by growth on formalin-killed bacteria labelled with [35s]sulphate, [3h]lysine or [14c]lysine. plasmodia were also labelled from radioactive lysine in the medium. 2. of 306 relatively abundant proteins examined, 26% were phase-specific, that is they were found only in amoebae or in plasmodia. about a quarter of these app ...19816786886
distribution studies on polytene chromosomes using antibodies directed against hnrnp.the distribution of nuclear ribonucleoprotein (hnrnp) particles in drosophila polytene chromosomes has been investigated using anti-b-36 serum as a probe. the use of polytene chromosomes allows resolution at the level of the chromomere, and provides the opportunity to look for both positive and negative correlations with transcriptional activity. the antiserum was obtained using the nuclear protein b-36 from physarum polycephalum as the immunogen. it has been shown to precipitate hnrnp particles ...19816788780
regulation of mitosis onset and thymidine kinase synthesis during the cell cycle of physarum polycephalum: action of aphidicolin.in physarum polycephalum (myxomycetes) aphidicolin has been found to delay metaphase onset when applied to synchronous plasmodia 3 h before control metaphase. in contrast to the action of temperature shifts, aphidicolin treatment did not delay the initiation of the increase of thymidine kinase synthesis (ec 2.7.1.21, atp-thymidine 5' phosphotransferase) and the decrease of the synthesis of thymidine kinase occurred normally after completion of mitosis in presence of aphidicolin. the amount of th ...19816793370
isolation and characterization of histones and other acid-soluble chromosomal proteins from physarum polycephalum.chromosomal basic proteins were isolated from amoebal and plasmodial stages of the acellular slime mold physarum polycephalum. polyacrylamide electrophoresis on high resolution acid-urea gels separated the five histone fractions in the sequence h1, h2a, h2b, h3, and h4. under these electrophoretic conditions physarum histones migrated more like plant (rye) than animal (calf) histones. furthermore, physarum histones h1, h2a, and h2b have higher molecular weights on sodium dodecyl sulfate (sds) ge ...19826805926
simultaneous oscillations of ca2+ efflux and tension generation in the permealized plasmodial strand of physarum.calcium is now generally thought to play a key role in regulating a variety of cellular movements. when the plasmodium of physarum polycephalum was treated with the calcium-ionophore a23187 or the quasi-ionophore amphotericin b, ca2+ leaked out. ca2+ efflux into the ambient solution from the plasmodial strand segment was measured by the luminescence of a photoprotein aequorin, and the tensile force production was recorded simultaneously. ca2+ efflux oscillated with the same period as the cycle o ...19816819083
structure of three-dimensionally rod-shaped mitochondrial nucleoids isolated from the slime mould physarum polycephalum.mitochondrial nucleoids were isolated from microplasmodia of the true slime mould physarum polycephalum using a discontinuous sucrose gradient following treatment of the mitochondria with nonidet p-40. studies of the isolated mitochondrial nucleoids by fluorescence and electron microscopy showed that the isolated structure was morphologically intact when compared with the structure in the mitochondria. scanning and negative staining electron micrographs of the isolated mitochondrial nucleoids in ...19826820795
organization of dna replication in physarum polycephalum. attachment of origins of replicons and replication forks to the nuclear matrix.we have investigated the attachment of the dna to the nuclear matrix during the division cycle of the plasmodial slime mold physarum polycephalum. the dna of plasmodia was pulse labelled at different times during the s phase and the label distribution was studied by graded dnase digestion of the matrix-dna complexes prepared from nuclei isolated by extraction with 2 m nacl. pulse labelled dna was preferentially recovered from the matrix bound residual dna at any time of the s phase. label incorp ...19836828380
isolation, identification, and characterization of histones from plasmodia of the true slime mold physarum polycephalum using extraction with guanidine hydrochloride.histones from plasmodia of the true slime mold physarum polycephalum have been prepared free of slime by an approach to histone isolation that uses extraction of nuclei with 40% guanidine hydrochloride and chromatography of the extract on bio-rex 70. this procedure followed by chromatography or electrophoresis has been used to obtain pure fractions of histones from physarum microplasmodia. physarum microplasmodia have five major histone fractions, and we show by amino acid analysis, apparent mol ...19836830762
patterns of histone acetylation in the cell cycle of physarum polycephalum.labeling of histones in the naturally synchronous cell cycle of physarum polycephalum with short pulses of tritiated acetate in vivo clearly showed three distinct patterns of histone acetate turnover. in g2 phase, turnover of acetate was observed only in histones h3 and h4, predominantly on the multiple acetylated forms. no acetate turnover was found in histones h2a and h2b compared with histones h3 and h4. in s phase, intense labeling was seen in all four core histones, in histones h3 and h4 pr ...19836838864
identification and changes in activity of five thymidine kinase forms during the cell cycle of physarum polycephalum.five forms of thymidine kinase have been identified on isoelectric focusing gels of physarum polycephalum supernatants. their isoelectric points are 5.9, 6.4, 6.7, 6.9 and 7.1. all are inhibited by deoxythymidine 5'-triphosphate (dttp). the activity of the pi 7.1 form does not change significantly during the cell cycle. the other four forms change in activity. about 1 h before metaphase the activity of the four more acidic forms is first detected. their activity peaks during telophase, and by 1 ...19836840201
response of the dtmp-synthesizing enzymes to differentiation processes in physarum polycephalum.synthesis of deoxythymidylate (dtmp) is a rate-limiting step in dna synthesis; there are two main enzymes which are responsible for dtmp production, thymidylate synthetase (ts) and thymidine kinase (tk). both enzymes were studied during several differentiation processes of the myxomycete physarum polycephalum. in all stages of proliferation (microplasmodia, macroplasmodia, germinating microsclerotia and germinating spores) tk is the dominant enzyme in terms of activity, whereas ts is the predomi ...19836840218
characterization of the thymidine kinase of physarum polycephalum.thymidine kinase [atp: thymidine 5'-phosphotransferase, ec 2.7.1.21] has been purified more than 3,500 fold from microplasmodia of physarum polycephalum. properties of the enzyme were determined on preparations purified 1,400 fold. thymidine was transformed to dtmp while a stoichiometric quantity of atp was transformed to adp. 5-iododeoxyuridine, 5-bromodeoxyuridine, and 5-fluorodeoxyuridine acted as competitive inhibitors for the thymidine substrate while 5-bromodeoxyuridine could be used as a ...19836841340
inheritance of extrachromosomal rdna in physarum polycephalum.in the acellular slime mold physarum polycephalum, the several hundred genes coding for rrna are located on linear extrachromosomal dna molecules of a discrete size, 60 kilobases. each molecule contains two genes that are arranged in a palindromic fashion and separated by a central spacer region. we investigated how rdna is inherited after meiosis. two physarum amoebal strains, each with an rdna recognizable by its restriction endonuclease cleavage pattern, were mated, the resulting diploid plas ...19836855770
morphological aspects of thiophosphorylated and dephosphorylated myosin molecules from the plasmodium of physarum polycephalum.electron microscopically, the myosin molecule from the plasmodium of physarum polycephalum has a long tail of 173 nm, having a flexible region over the range of 80 to 120 nm from the head-tail junction. in 0.6 m ammonium acetate, this region of the dephosphorylated myosin molecules is more flexible than that of the thiophosphorylated ones. in 50 mm ammonium acetate, the dephosphorylated myosin molecules exist in monomeric and oligomeric forms, independently of atp and mg2+, whereas the thiophosp ...19836863238
a cell-cycle-dependent protein of physarum polycephalum revealed by two-dimensional gel electrophoresis.silver-stained two-dimensional polyacrylamide gels of physarum polycephalum extracts have revealed no major changes in protein accumulation during the synchronous nuclear division cycle. however, one protein, or apparent mr 32 000 and isoelectric point 4.9, shows a reproducible ten-fold increase in total amount between early g2 phase and metaphase. this protein represents about 0.005% of total plasmodial protein.19836870852
energy metabolic regulation of oscillatory contraction activity in physarum polycephalum.the influence of inhibitors of respiration (kcn), glycolysis (2-deoxy-d-glucose alone or in combination with monoiodo-acetate) and anaerobic conditions (n2 or 95% n2 + 5% co2), as well as the effect of application of appropriate substrates (d-glucose, sodium acetate, alpha-ketoglutarate and pyruvate) on contraction behavior (of plasmodia) of physarum polycephalum was investigated under low intensity red-light illumination. application of inhibitors of respiration or glycolysis leads to significa ...19836871978
close relationship between certain nuclear and mitochondrial introns. implications for the mechanism of rna splicing.we present the first indication of a direct relationship between a nuclear and a mitochondrial splicing system. the intron in the precursor of the large, nuclearly coded ribosomal rna of two species of tetrahymena possesses all the features of a class of fungal mitochondrial introns. sequences conserved in mitochondrial introns of different fungal species are also found in the same order in these tetrahymena nuclear introns, and the intron rna can be folded to form a secondary structure similar ...19836876158
ca2+-dependent actin-binding phosphoprotein in physarum polycephalum. i. ca2+/actin-dependent inhibition of its phosphorylation.when crude extracts of the slime mold physarum polycephalum were incubated with atp and mg2+ at 35 degrees c, a peptide of approximately 42,000 da was predominantly phosphorylated. the kinase, separated from the phosphorylatable peptide, phosphorylated neither actin nor fragmin, both proteins of 42,000 da, the latter known to cap and shorten actin filaments in a ca2+-dependent manner. the phosphorylatable peptide was phosphorylated only at threonine residue(s), and its phosphorylation was almost ...19836885757
ca2+-dependent actin-binding phosphoprotein in physarum polycephalum. ii. ca2+-dependent f-actin-capping activity of subunit a and its regulation by phosphorylation of subunit b.cap 42 (a + b), a ca2+-dependent, actin-binding and phosphorylatable protein consisting of two distinct subunits a and b of 42,000 da in physarum polycephalum, has been identified as a new f-actin-capping protein. it capped or bound to the fast growing ends of actin filaments and blocked actin polymerization at this end. the capping activity residing in subunit a and its ca2+-dependency were regulated by phosphorylation of subunit b; subunit a required ca2+ for its capping activity when subunit ...19836885758
the influence of mechanical stimuli on the oscillatory contraction activity of physarum polycephalum. 19826890879
an actin-modulating protein from physarum polycephalum. i. isolation and purification.high-speed centrifugation supernatants from slime mould plasmodia show considerable activities to inhibit the polymerization of actin as revealed by viscosity measurements. by following increasing inhibitory activities an actin modulating protein (am-protein) has been isolated and purified which affects the polymer state of actin. am-protein has a peptide chain weight of 42 000 and is thus indistinguishable from actin by sds-electrophoresis, but can be clearly distinguished by isoelectric focuss ...19816894120
a correlation between in vivo and in vitro effects of the microtubule inhibitors colchicine, parbendazole and nocodazole on myxamoebae of physarum polycephalum.the effects of the microtubule inhibitors colchicine, parbendazole and nocodazole on the growth of myxamoebae of physarum polycephalum were closely paralleled by the effects of these drugs on the assembly in vitro of purified amoebal microtubule protein. colchicine at 100 microm did not inhibit amoebal growth and did not inhibit formation, or depolymerization, of amoebal microtubules. the benzimidazole carbamate derivatives nocodazole and parbendazole were very effective in both inhibiting growt ...19816895648
analysis of foldback sequences and repetitive sequences in cloned segments of nuclear dna from physarum polycephalum.the properties of dna segments containing foldback elements were studied after their selection from a "random" recombinant library of physarum polycephalum nuclear dna sequences, cloned using the plasmid vector pbr322. hybridisation of in vitro labelled recombinant plasmids to southern blots of genomic restriction fragments demonstrated that each cloned segment contained repetitive elements located at several hundred sites in the genome. two of the dna clones generated hybridisation patterns whi ...19826896288
blue-light receptor in a white mutant of physarum polycephalum mediates inhibition of spherulation and regulation of glucose metabolism.blue light induces sporulation of physarum polycephalum macroplasmodia and reversibly inhibits spherulation (sclerotization) of microplasmodia. illuminated microplasmodia have an abnormal appearance. the photobiological responses of the plasmodia appear to be unaffected by the absence of yellow pigment in the white mutant strain used. illumination of microplasmodial suspensions with blue light (lambda max approximately 465 nm) results also in an early effect on glucose metabolism: glucose consum ...19816940119
cytoplasmic polyadenylate processing events accompany the transfer of mrna from the free mrnp particles to the polysomes in physarum.the relationship between the mrna in the polysomes and the free cytoplasmic messenger ribonucleoprotein of physarum polycephalum was studied by microinjection techniques. labeled free cytoplasmic ribonucleoprotein, prepared from donor plasmodia, was microinjected into unlabeled host plasmodia, and its fat was followed in the host ribonucleoprotein particles. approximately one-half of the poly(a)-containing rna [poly(a)+rna] that originated from the microinjected particles was incorporated into t ...19816941265
periodic synthesis of microtubular proteins in the cell cycle of physarum.periodic polypeptide labeling over the naturally synchronous nuclear replication cycle of physarum polycephalum was analyzed by fluorography of two-dimensional electropherograms. two sets of polypeptides, denoted as p and q, showed strong periodicity; they were maximally labeled just prior to mitosis. this periodicity was shown to reflect synthesis rather than turnover or recovery. both p and q copolymerized with porcine microtubular proteins and displayed electrophoretic properties similar to t ...19816946448
phosphorylation of ornithine decarboxylase by a polyamine-dependent protein kinase.this paper presents evidence that a polyamine-dependent protein kinase (ec 2.7.1.37) purified from nuclei of the slime mold physarum polycephalum catalyzes phosphorylation of ornithine decarboxylase (orndcase; l-ornithine carboxy-lyase, ec 4.1.1.17). the protein kinase had properties similar to orndcase antizyme. phosphocellulose chromatography of nuclear preparations from p. polycephalum yielded the polyamine-dependent protein kinase of subunit mr 26,000 that was resolved from a second fraction ...19816946489
starvation phase of physarum polycephalum: characterization of transfer ribonucleic acid.we have begun a series of studies designed to characterize gene expression during differentiation in the slime mold physarum polycephalum. this work concerns the starvation phase of the sporulation sequence and describes some of the quantitative changes which occur in plasmodial constituents during the 3-day starvation period and also describes alterations in the transfer ribonucleic acid (trna) population. the results show that whereas the plasmodial trna content decreased by 75% during starvat ...19816965092
histone phosphorylation during radiation-induced mitotic delay in synchronous plasmodia of physarum polycephalum. 19806970737
locomotion of physarum polycephalum amoebae is guided by a short range interaction with e. coli. 19806986276
opposing kinetic effects of an acidic nucleolar phosphoprotein from physarum polycephalum on homologous and heterologous transcription systems. 19806993226
a comparison of tubulins from mammalian brain and physarum polycephalum using sds-polyacrylamide gel electrophorsis and peptide mapping. 19806995152
connectin, an elastic protein of muscle. a connectin-like protein from the plasmodium physarum polycephalum.a completely sodium dodecyl sulfate-insoluble protein was obtained from plasmodia of physarum polycephalum. the amino acid composition of this protein was very similar to that of connectin, an elastic protein of muscle. when the protein suspension was treated with 6 m guanidine-hcl in the presence of 0.1 m 2-mercaptoethanol, entanglements of very thin filaments, less than 5 nm in width, were observed under an electron microscope. since the network structure is almost the same as that of isolated ...19806998980
response of aspergillus nidulans and physarum polycephalum to microwave irradiation.the influence of microwaves on genetic processes in aspergillus nidulans and physarum polycephalum was investigated. suspensions of organisms were exposed in the far zone to 2450-mhz waves at 10 mw/cm2 for one hour in both cw and pulsed (1 microsecond, 600 pps) fields. spores of a. nidulans were irradiated before and during germination. no changes in survival rate or in frequency of morphological mutation were found. polycephalum under the influence of cw microwaves incorporated 3h-thymine into ...19807003154
isolation of cell cycle mutants of physarum polycephalum.asynchronous amoebal cultures of temperature-sensitive mutants of physarum polycephalum were examined cytologically, and two cell cycle mutants were identified. genetic analysis indicated that each mutant carried a single mutation that was expressed in both amoebal and plasmodial phases. thus it is possible to isolate cell cycle mutations expressed in plasmodia by initial isolation and analysis of amoebal mutants, a quicker procedure than the alternative of isolating plasmodial mutants directly. ...19807005625
the characterisation of a 5-s 'monosome' fraction from chromatin of physarum polycephalum.a so-called '5-s mononucleosome' fraction was isolated from nuclei of physarum polycephalum by digestion with micrococcal nuclease and subsequent fractionation by gel filtration. this fraction had electrophoretic and sedimentation properties which were similar to dna of approximately 140 base pairs in length. it is shown that lysis of the nuclei activates a protease which is resistant to phenyl-methyl sulphonyl fluoride, o-phenanthroline and parachloromercuri benzene sulphonate and which subsequ ...19817015286
structure around the 3' terminus of the 26s ribosomal rna gene of physarum polycephalum. 19817044892
aminoacyl-trnas from physarum polycephalum: patterns of codon recognition.isoacceptors of physarum polycephalum ala-, arg-, glu-, gln-, gly-, ile-, leu-, lys-, ser-, thr-, and val-trnas were resolved by reverse-phase chromatography and isolated, and their codon recognition properties were determined in a ribosomal binding assay. codon assignments were made to most isoacceptors, and they are summarized along with those determined in other studies from escherichia coli, yeasts, wheat germ, hymenoptera, xenopus, and mammals. the patterns of codon recognition by isoaccept ...19827047488
sulfhydryl groups of native myosin and of the myosin heavy chains from physarum polycephalum compared to vertebrate skeletal, smooth, and non-muscle myosins.although a previously reported analysis of physarum myosin detected no cysteine residues in the molecule, the myosin atpase activity was inhibited by p-chloromercuribenzoate. we have re-examined this apparently contradictory finding. we found highly purified plasmodial myosin to be very sensitive to n-ethylmaleimide inhibition of the k+, ca2+ -activated atpase. an estimate of the number of reactive sulfhydryls of the native myosin using ellman's reagent showed only 1.5 mol 11 min-reactive sulfhy ...19827055579
acceleration of mitosis induced by mitotic stimulators of physarum polycephalum. 19827056303
preparation of metaphase chromatin of physarum polycephalum without the loss of repressed rna synthesis. 19827073706
[uv-light-tested protein--dna interactions in the nuclei during the cell cycle in physarum polycephalum].the release of dnas from nuclear preparations isolated at different steps of the cell cycle of the synchronous culture of physarum polycephalum and irradiated with uv-light for 5 min (lambda 253.7 a, i = 1.8 . 10(2) j . m-2 . min-1) into 1% na-ds - 1.5 m nacl solution was studied. the value obtained correlated well with the degree of binding of interacting proteins with dna in chromatin and was identical for all the preparations tested with the only exception of the nuclei isolated at the end of ...19827074176
cell cycle-related transfer of proteins between the nucleus and cytoplasm of physarum polycephalum. 19827075701
cell cycle-dependent change in the phosphorylation of the nucleolar proteins of physarum polycephalum in vivo. 19827075776
thymidylate synthetase during synchronous nuclear division cycle and differentiation of physarum polycephalum.thymidylate synthetase and thymidine kinase activities in wild type strain m3b and in thymidine kinase-deficient mutant tu63 of physarum polycephalum are studied. whenever nuclear division occurs in macroplasmodia of wild type, thymidine kinase and thymidylate synthetase activities sharply increase, although the increase of thymidylate synthetase activity is less pronounced than thymidine kinase activity. this is also true for other investigated nuclear divisions during the life cycle of p. poly ...19827082674
relation of cytoplasmic calcium to contractility in physarum polycephalum.in a dumbbell-shaped plasmodium of physarum polycephalum showing active shuttle streaming ca was precipitated with potassium pyroantimonate (k[sb(oh)6]), and the distribution of ca between the cytoplasm and cellular organelles, especially vacuoles, was examined by electron microscopy. the contracting half-mass, where many empty vacuoles were present, was rich in the small ca precipitates located in the cytoplasm. the relaxing half-mass, where many ca-containing vacuoles were present, was poor in ...19827085783
changes in protein and rna during asexual differentiation of physarum polycephalum.some of the events during the growth and asexual differentiation of physarum polycephalum amoebae are described. encysted amoebae contain low levels of protein and rna. when these cells are mixed with bacteria and inoculated onto agar plates, there is an increase in cellular rna content followed by an increase in protein content. the cellular rna and protein contents of all strains tested decrease during the subsequent cell divisions. in nondifferentiating cells (strain cl at 30 degrees c and st ...19827093821
[synthesis of specific rna at the early s-stage of the cell cycle of the myxomycete physarum polycephalum].incorporation of [3h]uridine into polyribosomes and polyribosomal rna at different stages of the cell cycle of myxomycete physarum polycephalum was investigated. it has been shown that at the early s-stage (during the first hour after mitosis) there is no rrna synthesis. about 10--12% of polyribosomal rna, synthesized during this period is poly(a)+rna. approximately 50% of poly(a)-rna sediments as 4--6s and 20--25% as 7--14s in sucrose density gradient. it has been found that labeled rna is asso ...19827099156
characterization of ribosomal proteins of physarum polycephalum: number and molecular weight. 19827104828
microtubule nucleation by the isolated microtubule-organizing centre of physarum polycephalum myxamoebae.the nucleus--centrosome complex from physarum polycephalum myxamoebae has been purified. the complex contained the centriole pair and pericentriolar material in association with the nucleus. apart from some unusually stable microtubules, which appeared to be involved in maintaining the nucleus-centrosome association, endogenous microtubule arrays had been stripped from the complex during isolation. when the nucleus--centrosome complex was incubated with purified brain or myxamoebal tubulins the ...19827107728
electrical properties of the plasma membrane of microplasmodia of physarum polycephalum.microplasmodia of physarum polycephalum have been investigated by conventional electrophysiological techniques. in standard medium (30 mm k+, 4 mm ca++, 3 mm mg++, 18 mm citrate buffer, ph 4.7, 22 degrees c), the transmembrane potential difference vm is around -100 mv and the membrane resistance about 0.25 omega m2. vm is insensitive to light and changes of the na+/k+ ratio in the medium. without bivalent cations in the medium and/or in presence of metabolic inhibitors (cccp, cn-, n3-), vm drops ...19827108943
magnetic field effects on mitotic cycle length in physarum.large plasmodia of physarum polycephalum were formed from mixtures of micro-plasmodia grown in shaker cultures exposed to 2.0 g (rms), 75 hz magnetic fields and non-exposed, control cultures. the exposed cultures had been grown continuously in the field and displayed a longer mitotic cycle than the controls. mixed cultures display synchronous mitosis and a cycle length intermediate to the cycle lengths of exposed and control cultures. the cycle length of mixed cultures varied with the proportion ...19827117262
sporulation competence in physarum polycephalum cl and the requirement for dna replication and mitosis.the optimum conditions for sporulation and the requirements for mitosis and dna replication during the onset of the process have been investigated in plasmodia of the cl strain of physarum polycephalum. a 72 h period of starvation was necessary before a plasmodium became competent to sporulate on exposure to light. the plasmodium became irreversibly committed to sporulation 4 to 5 h after illumination. the commitment point was related to the time of illumination rather than the duration of starv ...19827119741
sequence-specific cleavage of chromatin by staphylococcal nuclease can generate an atypical nucleosome pattern.we have investigated the nucleosomal organization of ribosomal genes in the acellular slime mold physarum polycephalum. when probed with staphylococcal nuclease, the ribosomal genes appear to be uniformly packed in nucleosomes, in an arrangement which is indistinguishable from the pattern obtained with bulk chromatin. during this study, an unusual pattern of digestion was obtained from a dna region immediately upstream of the initiation site of rrna transcription, in addition to the nucleosomal ...19827122237
distribution of intramembranous particles in the plasmalemma of physarum polycephalum during sclerotization, spore-formation and spore-germination. 19827127491
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