| the core histones from the slime mold physarum polycephalum. isolation and characterization. | the histones of physarum polycephalum have been isolated and fractionated using a combination of gel exclusion and ion-exchange chromatography or differential precipitation. the four core histones were unambiguously identified by gel electrophoresis, amino acid composition and n-terminal analysis. the molecular weight of physarum histones h3, h2b and h4 are very close or identical to the corresponding histones from chicken erythrocytes. physarum h2a is significantly larger than chicken erythrocy ... | 1982 | 7128589 |
| blue light influences gene expression and motility in starving microplasmodia of physarum polycephalum. | the differentiation of starving physarum polycephalum microplasmodia into resting structures (spherules) was studied. early events in this differentiation pathway include decreases in both plasmodial motility and protein synthesis. the starving plasmodia show a blue light avoidance response. blue light (lambda max 450 nm, irradiance 16 w/m2) acts antagonistically to the starvation stimulus so that spherule formation is inhibited [16]. light affects each of the above mentioned events of the diffe ... | 1982 | 7128614 |
| regulatory mechanism in smooth muscle: actin-linked regulation. | our view about the ca regulation of smooth muscle contraction can be summarized as follows: the regulatory system is actin-linked and consists of tropomyosin and leiotonin; the latter is a complex of two proteins, leiotonin a, the regulatory moiety, and leiotonin c, the ca-binding moiety. leiotonin resembles troponin in some respects, but is clearly different in that it has no affinity for tropomyosin and is effective at a leiotonin/actin molar ratio of less than 1:50. the methods of preparing l ... | 1982 | 7128833 |
| [comparison of endogenous nuclear rna-polymerase ii at different stages of mycoplasmodial growth]. | the nuclei of physarum polycephalum isolated from the 48- and 96-hour-old growing microplasmodium differ 7-8 fold by the rates of [3h]utp incorporation in vitro accompanied by a slight (approximately 1.6 fold) change in concentration of endogenous rna-polymerase ii. using mild fragmentation of chromatin nuclei by micrococcal nuclease and deae-sephadex chromatography the bound enzyme was shown to consist of two forms differing in the degree of their binding to the template and in functional signi ... | 1982 | 7138969 |
| [physico-chemical properties of cyclic nucleotide-independent protein kinase from the myxomycete physarum polycephalum]. | some physico-chemical properties of cyclic nucleotide-independent protein kinase from the myxomycete physarum polycephalum were studied. the enzyme is not activated by ca2+ and double-stranded rna of poly(a)-poly(y). the nature of the amino acid, target for phosphorylation, for the homogenous enzyme was established by two-dimensional electrophoresis, using casein as a protein substrate. the enzyme exclusively phosphorylates threonine residues in the casein molecule. | 1982 | 7138971 |
| induction of heat-shock proteins at permissive growth temperatures in the plasmodium of the myxomycete physarum polycephalum. | when synchronous plasmodia of the myxomycete physarum polycephalum were submitted to temperature shifts from 22 degrees c to 32 degrees c, the highest physiological temperature, protein synthesis was increased during at least 10 h. moreover during 2 h, four proteins (69, 74, 82 and 105 kda) showed a transient increase of their synthesis, independently of the period of the temperature shift during the cell cycle. the stability of these proteins and the susceptibility of their synthesis to actinom ... | 1982 | 7140759 |
| posttranslational control of ornithine decarboxylase by polyamine-dependent protein kinase. | in nuclei and nucleoli of the slime mold physarum polycephalum, ornithine decarboxylase (orndcase) (mr 70,000) is phosphorylated by a protein kinase reaction that is dependent on spermidine and spermine. putrescine antagonizes the phosphorylation. phosphorylation of orndcase inhibits its capacity to catalyze decarboxylation of ornithine. the protein kinase that catalyzes this phosphorylation has many properties similar to those of nuclear protein kinase ii, or type g, which has been studied by o ... | 1982 | 7141003 |
| dna replication in physarum polycephalum: electron microscopic analysis of patterns of dna replication in the presence of cycloheximide. | dna from synchronously replicating nuclei of physarum polycephalum was studied electron microscopically after 15, 30, 60, and 90 or 120 min of replication in the presence or absence of the protein synthesis inhibitor cycloheximide. the replication-loop size-distribution showed that replication fork progression is severely retarded in the presence of cycloheximide. analysis of replication-loop frequency showed a similar pattern in control and cyclo-heximide-treated samples, with an increase from ... | 1982 | 7142290 |
| amine-specificity of the inactivating ornithine decarboxylase modification in physarum polycephalum. | the enzyme catalysing the polyamine-stimulated modification of physarum ornithine decarboxylase in vivo was partially purified and its activity on purified ornithine decarboxylase was examined with respect to its specificity for various amines. spermidine, spermine and several polyamine analogues strongly promoted this reaction in vitro (apparent km in the 0.1--0.5 mm range), whereas putrescine (apparent km 5.33 mm) and several related diamines were not nearly as effective. in agreement with thi ... | 1982 | 7150232 |
| control of histone gene expression in physarum polycephalum. i. protein synthesis during the cell cycle. | synchronous cultures of physarum polycephalum were pulsed with [3h]lysine hydrochloride in s and g2 phases of the cell cycle. plasmodial extracts were separated into nuclear, ribosomal and acid-soluble post-ribosomal cytoplasmic fractions. core histones could be detected by staining in the nuclear fractions of both s and g2 phases, but were not detected by staining in the cytoplasmic fractions. newly synthesized histone was present in s-phase nuclei but not in s-phase cytoplasm. the specific act ... | 1982 | 7153256 |
| changes in intracellular ph accompanying chemoreception in the plasmodia of physarum polycephalum. | a new method for measuring intracellular ph, employing the intrinsic fluorescent pigments of the plasmodia of the myxomycete physarum polycephalum, was used to study the role of ph in chemotactic transduction in the plasmodia. the cell became acidified following stimulation with the attractants alanine, glucose, galactose and maltose when their concentrations exceeded the respective thresholds of chemoreception and taxis. the degree of cell acidification paralleled the relaxing tendency in tensi ... | 1982 | 7153759 |
| cell cycle-fluctuations in concentration of various elements in cytoplasm and in nucleus/chromatin of physarum polycephalum. | the concentrations of na, mg, p, cl, s, k, and ca (m mol/kg dry wt) were measured during the cell cycle of p. polycephalum using electron-probe x-ray microanalysis. significant cell cycle-associated fluctuations in the concentrations of all of these elements occurs in both the cytoplasm and the nucleus. in most cases the levels of each element were elevated during mitosis but greatly reduced during the s phase. phosphorus and sulphur were concentrated in the nucleus/chromatin at metaphase. ultra ... | 1982 | 7160223 |
| the motive force of the migrating pseudoplasmodium of dictyostelium discoideum under dark and light conditions. | as a contribution to the understanding of the mechanism of the collective motion of the cell mass in the migrating pseudoplasmodium its motive force has been determined. the measurements in the present paper were made by an original method using centrifugal force. the maximum value of the motive force of a migrating pseudoplasmodium in the dark was estimated as 0.6-1.6 dyn. this value is comparable to the motive force of protoplasmic streaming in physarum polycephalum. in addition, the motive fo ... | 1982 | 7166560 |
| control of mitotic synchrony in physarum polycephalum. phase shifting by fusion of heterophasic plasmodia contradicts a limit cycle oscillator model. | fusion of two multinuclear plasmodia of physarum polycephalum representing different stages of the mitotic cycle causes a rapid mitotic synchronization of "young" (a) and "old" (b) nuclei [2, 14, 19]. this communication reveals that even at large phase differences synchronization always occurs by advancing "young" and retarding "old" nuclei. this strongly contradicts a limit cycle oscillator model [8] which would permit synchronization on the shorter arc of the phase circle (advancing b and reta ... | 1982 | 7173216 |
| cell-cycle-dependent effects of sodium-n-butyrate in physarum polycephalum. | sodium-n-butyrate affects the length of the mitotic cycle of physarum polycephalum. application during s- or early g2-period results in a delay of the subsequent mitosis, whereas application later in the cycle has no delaying effect. interestingly, the second mitotic cycle after application is considerably shortened when butyrate has been administered during s- or early g2-period of the preceding cycle. in comparison, other homologous short-chain fatty acids were tested; the retarding effect on ... | 1982 | 7183689 |
| studies on microplasmodia of physarum polycephalum. i. classification and locomotion behavior. | depending on the conditions of the axenic shuttle culture, microplasmodia of the acellular slime mold physarum polycephalum can be subdivided into three classes regarding fine structural organization and protoplasmic streaming activity: (1) spherical and rod-shaped types, (b) ameboid types, and (c) symmetrical types. in ameboid microplasmodia, the motive force for the irregular protoplasmic streaming activity is generated by alternative contraction and relaxation of a membrane-associated layer, ... | 1980 | 7191783 |
| effect of microtubule-disrupting drugs on protein and rna synthesis in physarum polycephalum amoebae. | the effects of the microtubule-disrupting drugs, colchicine, vinblastine, podophyllotoxin, griseofulvin, and lumicolchicine (10(-5) m), on protein and rna synthesis were studied in physarum polycephalum amoebae in culture. all, except lumicolchicine, were found to simultaneously reduce the rate of protein synthesis and stimulate rna synthesis. these results parallel the effects seen in cells exposed to heat shock. treatment of cells with a microfilament-disrupting drug, cytochalasin b (10 microg ... | 1980 | 7192968 |
| the influence of an actin-modulating protein (am-protein) from physarum polycephalum on the cell motility of amoeba proteus. | an actin-modulating protein (am-protein) isolated from the acellular slime mold physarum polycephalum and microinjected into living amoeba proteus causes characteristic changes in cell shape, locomotory behaviour, and organization of the microfilament system of the amebae. the peptide chain weight of the am-protein, which binds to one actin molecule with high affinity thus forming a heterodimer, is 43 000. the heterodimer is a powerful inhibitor of actin polymerization, when added to g-actin. a ... | 1980 | 7193137 |
| cytoplasmic actomyosin fibrils after preservation with high pressure freezing. | the fine structure of the actomyosin system of physarum polycephalum was investigated in vitrified specimens after applying a pressure of greater than 2.1 kbar and freezing rates of 500 to 5,000 degrees c/s. the frozen specimens were either freeze-substituted or freeze-fractured and compared with material processed according to conventional methods of freeze-etching preparation. artifactual alterations, as seen in the form of destroyed areas of the cytoplasm after chemical fixation, were not obs ... | 1981 | 7195774 |
| cell fusion competence and its induction in physarum polycephalum and didymium iridis. | | 1982 | 7199495 |
| endoplasmic veins from plasmodia of physarum polycephalum: a new strand model defined age, structure, and behavior. | pure endoplasm from plasmodia of physarum polycephalum taken up into glass pipettes and subsequently extruded into water forms a long protoplasmic cylinder uniform in diameter, which is designated as an "endoplasmic vein". this new experimentally obtained model has proven advantageous for tensiometric investigation of contraction activity. during the process of aging, this model undergoes processes of 1. actin transformations, 2. cytoplasmic actomyosin fibrillogenesis and 3. development of a new ... | 1982 | 7200885 |
| cycloheximide resistance of physarum polycephalum. | in the presence of cycloheximide, wild-type plasmodia of physarum polycephalum exhibit an immediate decrease in deoxyribonucleic acid synthesis, a reduction in the incorporation of [3h]thymidine into thymidine triphosphate, and an increase in the level of thymidine triphosphate, as well as a decrease in protein synthesis. in this study, we have utilized a cycloheximide-resistant (cycr) amoebic strain selected from a population of cells mutagenized with nitrosoguanidine. segregation data indicate ... | 1980 | 7204337 |
| association of newly replicated dna with the nuclear matrix of physarum polycephalum. | we have studied the role of the nuclear matrix in dna replication in a naturally synchronized eucaryote, physarum polycephalum. when p. polycephalum. when p. polycephalum macroplasmodia were pulse labeled with 3h-thymidine, the dna remaining tightly associated with the matrix was highly enriched in newly synthesized dna. this enrichment was found both in nuclei that had just initiated dna replication as well as in nuclei isolated later during s phase. pulse chase experiments showed that the asso ... | 1981 | 7208354 |
| [radiosensitivity of synchronous and asynchronous cultures of the myxomycete, physarum polycephalum in gamma irradiation]. | | 1980 | 7208831 |
| protein factor which induces conversion between physarum ornithine decarboxylase forms in vitro. | the rapid activity modulation of ornithine decarboxylase (l-ornithine carboxy-lyase, ec 4.1.1.17) in physarum polycephalum is closely correlated with a reversible post-translational modification of this enzyme. a factor has now been isolated from homogenates of exponentially-grown microplasmodia which catalyzes the conversion of the active enzyme form, a, into its less active, b state. partial purification of this a-b converting factor has been achieved using deae-sephacel chromatography and ult ... | 1981 | 7213746 |
| protoplasmic streaming during the cell cycle of physarum polycephalum. | | 1981 | 7215460 |
| thymidine-dependent growth of physarum polycephalum amoebae treated with methotrexate in axenic culture. | | 1981 | 7215461 |
| cell cycle dependent change in the endogenous phosphorylation of nucleolar proteins of physarum polycephalum. | | 1981 | 7215555 |
| hexosamine metabolism during spherule formation in physarum polycephalum. | hexosamine metabolism in relation to the spherule-wall synthesis in physarum polycephalum was studied by the incorporation of labeled sugar into the wall and intermediary compounds in the biosynthesis of wall polysaccharide. the incorporation of [14c]galactosamine into the wall material occurred after a lag period of about 10 h in an induction medium. nucleotides and sugar phosphates in the acid-soluble fraction of spherulating plasmodia were analyzed by column chromatography on dowex 1-x8 (form ... | 1981 | 7225417 |
| the pathway of photosensory transduction in physarum polycephalum. | irradiation of the plasmodia of physarum with blue and white light results in a transient change of theie oscillatory contraction frequency. this reaction to light decreases with increasing distance from the illuminated area (block and wohlfarth-bottermann, 1981). the first local appearance of light response in non-illuminated parts of the plasmodia was used to analyse the sensory pathway of the light stimulus modulating the contractile apparatus. different experimental assays revealed that the ... | 1981 | 7226251 |
| ionic currents traverse the slime mould physarum. | self generated electric currents were studied in protoplasmic drops and small plasmodia of physarum polycephalum with the aid of an extracellularly measuring vibrating electrode. ionic currents up to 15 microamperemetercm-2 density were found to traverse the objects. in protoplasmic drops current always enters the numerous protrusions and leaves areas with a smooth surface. in monopodial plasmodia current enters the strand and leaves both the advancing front and the retracting end. this result p ... | 1981 | 7226252 |
| new polypeptide chains associated with highly purified rna polymerase ii or b from physarum polycephalum. | | 1981 | 7227535 |
| polyamine-activated protein kinase reaction from nuclei and nucleoli of physarum polycephalum which phosphorylates a unique mr 70 000 nonhistone protein. | methods are described for the detection and purification of a protein kinase from nuclei and nucleoli of physarum polycephalum which catalyzed transfer of phosphate from [gamma-32p]atp to a unique nonhistone protein of mr 70 000 in a reaction that was polyamine dependent. enzymatic phosphorylation of the nonhistone protein by the purified protein kinase was stimulated greatly, at times more than 60-fold, by the polyamines spermidine and spermine. this unique polyamine-dependent reaction was loca ... | 1981 | 7236618 |
| [dependence of rna synthesis in the cell of physarum polycephalum on concentration and activity of rna-polymerase ii]. | the rna synthesis detected by incorporation of [h3]uridine chase label proceeds in macroplasmodium and in isolated nuclei throughout the cell cycle of a synchronous myxomycetes culture of physarum polycephalum, producing two well-shaped peaks at the postmitotic and premitotic steps. such rna synthesis is due to the activity of alpha-amanitin-sensitive rna-polymerase ii. concentrations of rna-polymerase ii at various steps of the cell cycle were determined by alpha-amanitin titration; the specifi ... | 1981 | 7248387 |
| analysis of development and growth in a mutant of physarum polycephalum with defective cytokinesis. | | 1981 | 7250516 |
| post-fusion incompatibility in physarum polycephalum. the involvement of dna. | the lethal reaction following fusion of plasmodia of a sensitive and a killer strain of physarum polycephalum could be prevented by the incorporation of 5-bromo-2'-deoxyuridine in both strains. this result suggests the involvement of transcription in the lethal reaction. although under appropriate conditions fusion of the strains is not followed by a lethal reaction the fused plasmodium will behave as the killer strain after subculturing. at different times after fusion, dna was isolated from a ... | 1981 | 7259407 |
| the structure of chromatin synthesized in the presence of cycloheximide in physarum polycephalum. | the effect of cycloheximide on protein and dna synthesis and on the structure of chromatin was studied. changes in the rate and extent of dna synthesis in response to cycloheximide were highly variable in contrast to the extremely rapid and reproducible inhibition of protein synthesis. no differences in the rate of the release of acid-soluble products by nucleases and in the nature of the nucleoprotein particles were found in chromatin from plasmodia treated and non-treated with cycloheximide. i ... | 1980 | 7269969 |
| some unusual features of physarum polycephalum chromatin are due to the presence of slime. | chromatin of lower eukaryote physarum polycephalum, while showing typical nucleosomal organization, reveals upon digestion with micrococcal nuclease certain features not found in chromatins of higher eukaryotes, the most pronounced of which is the unusual pattern of degradation of core-size dna, without accumulation of subcore fragments. it has been shown that these peculiarities are not due to intrinsic features of physarum nucleohistone complex but to the presence of a specific polysaccharide, ... | 1980 | 7269980 |
| flow cytofluorometric analysis of the nuclear division cycle of physarum polycephalum plasmodia. | the nuclear cycle kinetics of physarum polycephalum plasmodia were examined using flow cytofluorometry. the dyes hoechst 33342 and propidium iodide were used to stain the dna of isolated nuclei. in asynchronously growing microplasmodia. s phase consists of 13--15% of the nuclear division cycle time. nuclei isolated from individual macroplasmodia, which have previously been demonstrated to divide in synchrony, were shown to be less synchronized during late s phase than during mitosis. the results ... | 1981 | 7273974 |
| isolation by preparative electrophoresis and characterization of histone p3 from the slime mold physarum polycephalum. | | 1981 | 7274533 |
| ultrastructure of the nuclear matrix from physarum polycephalum during the mitotic cycle. | | 1981 | 7277571 |
| cell-cycle-dependent dissociation of histone h1 from chromatin in nuclei of p. polycephalum. | the dissociation curves of histone h1 from chromatin in interphase and metaphase nuclei from physarum polycephalum have been determined using cacl2 as dissociating agent. h1 is less strongly bound to metaphase chromosomes than to interphase chromatin. however, no differences could be detected in the binding of hl to early s, late s or g2 phase chromatin. the number of cacl2 molecules involved in binding one h1 molecule to chromatin was reduced from 5 in interphase to 4 in metaphase. the non-elec ... | 1981 | 7279675 |
| the effect of longitudinal tension on the amplitude of the contraction rhythm of plasmodial strands of physarum polycephalum. | plasmodial strands of physarum polycephalum exhibit a characteristic contraction rhythm. the amplitude of the isotonic tension increased linearly with the cube root of relative stress. the period of the isometric tension increased linearly with the amplitude of the oscillation, but stayed constant above a critical value. the above empirical formulae were found applicable for all temperatures employed, 9 to 28 degrees c, but different temperature coefficients were observed below and above 15 to 1 ... | 1981 | 7285954 |
| protein tightly bound near the termini of the physarum extrachromosomal rdna palindrome. | the genes coding for ribosomal rna in plasmodia of physarum polycephalum are arranged palindromically on extrachromosomal rdna molecules of 61 kb (kilobasepairs). incubation of mildly extracted rdna with the 125i bolton-hunter reagent results in incorporation of label not removed by sds, cscl, or various organic solvents. labeled protein is preferentially associated with terminal rdna restriction fragments, as detected after gel electrophoresis of the dna. antibody reaction with dinitrophenylate ... | 1981 | 7298725 |
| preferential synthesis of low-molecular-weight rna in uv-irradiated plasmodia of physarum polycephalum. | | 1981 | 7302130 |
| effects of 163-nm vacuum uv radiation on the initiation of mitosis in physarum polycephalum. | | 1981 | 7302134 |
| [structural study of the chromatin of the myxomycete physarum polycephalum in the mitotic cycle]. | the chromatin structure of physarum polycephalum was studied with electron microscope at different phases of its mitotic cycle. at the s-phase and during mitosis, the chromatin has a nucleosomal structure. at the early g2-phase the chromatin structure changes, long regions of non-beaded structure being found in the chromatin fibers. at the late g2-phase, the major part of chromatin loses its globular organization, with chromatin fibres without a pronounced subunit structure prevailing in the pre ... | 1981 | 7303157 |
| turnover rates of phosphoryl groups in ribosomal proteins of physarum polycephalum. evidence for two different mechanisms. | the rate of phosphate exchange in individual ribosomal proteins of physarum polycephalum was determined in vivo. it was observed that the phosphoryl groups of s3, the major phosphoprotein, had a turnover rate of 1.5% per minute. the phosphoryl groups of proteins l1, l20 and l24 were stable. these results show that the phosphorylation of ribosomal proteins is regulated by at least two different mechanisms. the rapid turnover of phosphoryl groups of the major phosphoprotein is in agreement with th ... | 1981 | 7308210 |
| nuclear pores during the cell cycle in a slime mold, physarum polycephalum. | freeze-fracture and thin sectioning techniques were used to follow in large synchronous plasmodia of physarum polycephalum the changes in number and distribution of nuclear pores during the cell cycle. using freeze-fracture, we determined that average pore frequency rises gradually from 14/micrometers(2) of nuclear envelope surface at early s to a value of about 22 just before prophase. nuclear diameter averaged 3.3 micrometers at early s and increased to 4.3 micrometers at late g2. calculating ... | 1981 | 7314078 |
| different chromatin structures in physarum polycephalum: a special form of transcriptionally active chromatin devoid of nucleosomal particles. | nonnucleolar chromatin from interphase nuclei of physarum polycephalum plasmodia occurs in two different structural configurations as seen in electron microscopic spread preparations. while the majority of the chromatin is devoid of nascent ribonucleoprotein (rnp) fibrils and compacted into nucleosomal particles, a minor proportion (10-20%) is organized differently and reveals a smooth contour. it is this form of smooth chromatin which is rich in transcription units (mean length: 1.36 +/- 0.21 m ... | 1981 | 7327047 |
| regulation of protein synthesis in the plasmodial phase of physarum polycephalum. | 1. the rate of protein synthesis changes very little during the first 2-3 h (s phase) of the nuclear division cycle in plasmodia of physarum polycephalum and then increases continuously during g2 phase, so that by the end of the cycle the rate has doubled relative to that in s phase. protein synthesis appears to continue during mitosis. 2. fractionation of extracts of plasmodia, labeled with [3h]lysine for 1 h, by two-dimensional electrophoresis indicated that most if not all proteins are synthe ... | 1981 | 7333278 |
| the nucleotide sequence of 5s ribosomal rna from slime mold physarum polycephalum. | the nucleotide sequence of 5s ribosomal rna from plasmodia of the slime mold physarum polycephalum was determined as pppggaugcggc cauacuaagg 20 agaaagcacc 30 ucaucccguc 40 cgaucugaga 50 aguuaagcuc 60 cuucaggcgu 70 gguuaguacu 80 gggguggggg 90 accaccuggg 100 aaucccacgu 110 gcugcauucu 120 uoh by chemical and enzymatic gel sequencing technics using 3' and 5' end-labeled rna. this rna is very different from 5s rrna of the cellular slime mold dictyostelium discoideum (36 nucleotides are different), an ... | 1981 | 7333996 |
| origin of the membrane potential in plasmodial droplets of physarum polycephalum. evidence for an electrogenic pump. | spherical droplets, derived from physarum plasmodia by incubation in 10 mm caffeine, seemed to be an excellent system for electrophysiological studies because they were large (less than or equal to 300 micrometer in diameter) and because they tolerated intracellular electrodes filled with 3 m kcl and 10 mm edta for a few hours. intact plasmodia, by contrast, gave valid records for only a few minutes. under standard conditions ([k+]o = 1 mm, [na+]o = 5 mm, [ca++]0 = 0.5 mm, [mg++]o = 2 mm, and [c ... | 1981 | 7334328 |
| regulation of thymidine kinase synthesis during the cell cycle of physarum polycephalum: the effects of two microtubule inhibitors. | methyl benzimidazole carbamate and griseofulvin are two microtubule inhibitors which perturb plasmodial mitosis in physarum polycephalum. these two compounds perturb not only the mitotic process leading to abortive mitosis but delay the onset of mitosis. both drugs delayed the onset of thymidine kinase synthesis (ec 2.7.1.21, atp: thymidine 5'phosphotransferase) which occurred concomitantly with mitosis. thus, thymidine kinase synthesis, a cell cycle event which is not thought to have any relati ... | 1981 | 7338074 |
| a flow cytometry study of the cell cycle and of ploidy levels in physarum polycephalum myxamoebae and plasmodia. | the cell cycle of physarum polycephalum myxamoebae, as well as haploid and diploid and plasmodia, was analysed using laser microfluorometry. the data obtained indicate that the cell cycle of all strains examined are similar. the dna profiles also indicate that a haploid ploidy level is still uncertain and show conclusively that spontaneous chromosome loss is a parameter of concern in research involving these organisms. | 1981 | 7339444 |
| dna replication in physarum polycephalum. analysis of replicating nuclear dna using the electron microscope. | dna has been isolated from physarum polycephalum nuclei obtained from macroplasmodia at different stages in the mitotic cycle, and examined using the electron microscope. putative replicating structures were identified, the majority of which contained clusters of 2--37 'microbubbles', each microbubble corresponding to a segment of dna 100--5000 nucleotides long. the microbubble-containing structures are unstable in the formamide hyperphase used to prepare specimens for electron microscopy, possi ... | 1980 | 7341224 |
| thymidine kinase enzyme variants in the life cycle of physarum polycephalum. | | 1980 | 7358085 |
| sequence organisation in nuclear dna from physarum polycephalum. interspersion of repetitive and single-copy sequences. | nuclear dna from physarum polycephalum is shown to contain three sequence components by reassociation kinetic analysis; a foldback component consisting of 6% of the dna, a component with the properties of repetitive sequences comprising 31% of the dna, and a majority component containing 63% of the dna which reassociates with the kinetics characteristic of single-copy sequences. the complement of repetitive sequences is comprised of about 80 families of repeated elements, each containing approxi ... | 1980 | 7363891 |
| more evidence for replication-transcription-coupling in physarum polycephalum. | endogenous rna polymerase activity of isolated nuclei from physarum polycephalum was determined at high (400 mm kcl) and low (5--100 mm kcl) ionic strength. the activity of rna polymerase b (alpha-amanitin-sensitive ump incorporation) and of rna polymerase a (plus c) (alpha-amanitin-resistant ump incorporation) was compared in accurately sized nuclear samples derived from macroplasmodia at distinct points of the mitotic cycle. minimum total rna polymerase activity was detected in metaphase nucle ... | 1980 | 7364877 |
| tension generation by actomyosin thread from a non-muscle system. | a suitable motility model reconstituted from non-muscle contractile proteins should offer a powerful tool for analysing the molecular events in cell motility. actomyosin thread has been thought to be such a model. as far as non-muscle motile systems are concerned, however, only a very limited number of experiments have been done in this direction. no direct measurement of the tension produced by non-muscular actomyosin thread has been reported in spite of its importance for quantitative studies. ... | 1980 | 7374767 |
| cell cycle changes in physarum polycephalum histone h1 phosphate: relationship to deoxyribonucleic acid binding and chromosome condensation. | we have examined the relationship of phosphate content in histone h1 of physarum polycephalum to mitotic chromosome condensation and affinity for deoxyribonucleic acid (dna). h1 undergoes a series of posttranslational phosphorylations which increase its apparent molecular weight on nadodso4-polyacrylamide gels. our studies confirm the observation by bradbury and co-workers [bradbury, e. m., inglis, r. j., matthews, h. r., & sarner, n (1973) eur. j. biochem. 33, 131-139; bradbury, e. m., inglis, ... | 1980 | 7378358 |
| the poly(adenylic acid)-protein complex is restricted to the nonpolysomal messenger ribonucleoprotein of physarum polycephalum. | the distribution of poly(adenylic acid) [poly(a)]-protein complexes in the polysomal and nonpolysomal messenger ribonucleoprotein (mrnp) fractions of physarum polycephalum was examined in the present study. poly-(a)-containing components released from the nonpolysomal mrnp by ribonuclease (rnase) digestion were quantitatively adsorbed to nitrocellulose filters at low ionic strength, were highly resistant to micrococcal nuclease under conditions in which free poly(a) was completely degraded, and ... | 1980 | 7378386 |
| arginine synthesis and nitrogen excretion in the myxomycete physarum polycephalum. | the nitrogen excretory metabolism of the myxomycete physarum polycephalum was studied. when cultured in partially defined broth medium or on agar, the principal excretory product was ammonia nitrogen. a small, variable quantity of urea was excreted in liquid culture. no uric acid or other purines were detected in the cultures. when microplasmodia were incubated with sodium [14c]bicarbonate, radioisotope was incorporated into citrulline, arginine, and urea. incubation with l-[carbamoyl-14c]citrul ... | 1980 | 7378943 |
| protein-bound mono(adp-ribose) residues in differentiating cells of dictyostelium discoideum. | changes in protein-bound mono(adp-ribose) residues during development of dictyostelium discoideum were determined. nad(h) levels and the amounts of the nh2oh resistant and sensitive subfractions of mono(adpr) were found not to be different between exponentially growing and aggregation-competent cells in which mitosis had ceased. divergent changes occurred at the differentiation stages following aggregation as indicated by an increase in the ratio of these subfractions from approx. 1 during the g ... | 1980 | 7379135 |
| selective suppression of positive chemotaxis in physarum polycephalum by treatment with rotenone or under anaerobic condition. | the chemotactic motive force of plasmodia of physarum polycephalum was measured by the double-chamber method. the treatment of plasmodia with 0.1 mm rotenone did not affect the motility of the palsmodia but led to suppression of the chemotaxis toward all the attractants examined (glucose, galactose, c-amp, kh2po4). rotenone treatment did not affect the chemotaxis against repellents (fructose, nacl). similar results were obtained when the chemotactic motive force was measured under an anaerobic c ... | 1980 | 7379798 |
| thymidine kinase-deficient mutants of physarum polycephalum; relationships between enzyme activity levels and ploidy. | thymidine (tk) and deoxycytidine (dck) kinase levels, chromosome counts and whole culture protein:dna ratios have been determined in the tk- plasmodial strains of p. polycephalum--tu84 and tu63--and on several wild type (wt) plasmodial and amoebal strains from wis 1 and colonia backgrounds. it was found that (a) dck levels and protein:dna ratios were similar in all plasmodia, regardless of ploidy or genetic background; (b) tu84 and 63 were haploid; (c) tk specific activity was similar in all wt ... | 1980 | 7388966 |
| culture methods and sporulation of physarum polycephalum. | | 1980 | 7402211 |
| sequence organization in nuclear deoxyribonucleic acid from physarum polycephalum. physical properties of foldback sequences. | an investigation was performed with the use of physical techniques, to determine the nature and organization of inverted repeat sequences in nuclear dna fragments from physarum polycephalum. from the average size of foldback duplexes (550 nucleotide pairs), and the foldback duplex yield as determined by treatment of dna with s1 deoxyribonuclease followed by hydroxyapatite chromatography, it is estimated that there are at least 25000 foldback sequences in the physarum genome. foldback dna molecul ... | 1980 | 7406856 |
| acetylation of histone h4 and its role in chromatin structure and function. | histone h4 is a highly conserved structural component of the nucleosome subunit of chromatin. the activation of chromatin is accompanied by changes in structure which may be caused by histone modification or by interactions of specific non-histone proteins, or both. histone h4 can be modified by acetylation and this modification has been correlated with chromosome assembly and with transcription. we have now tested these correlations by studying h4 acetate content as a function of the cell cycle ... | 1980 | 7412879 |
| isolation of newly-initiated dna from the early s phase of the synchronous eukaryote, physarum polycephalum. | | 1980 | 7428812 |
| isolation and susceptibility to nucleases of transcriptionally active and inactive chromatin fractions from physarum polycephalum. | transcriptionally active and inactive chromatin fractions were isolated from physarum polycephalum after depolymerization of chromatin with dnaase ii or micrococcal nuclease, followed by fractionation in 5 mm-mgcl2. the active fraction of chromatin comprised up to 21% of nuclear dna and was enriched 22-fold in the labelled nascent rna. both chromatin fractions were shown to have the nucleosomal structure. dna of the active fraction of chromatin was degraded much faster with dnaase i and micrococ ... | 1980 | 7435080 |
| muliple sites of action of cycloheximide in addition to inhibition of protein synthesis in physarum polycephalum. | the specificity action of cycloheximide was tested using a cycloheximide resistant mutant of physarum polycephalum. this resistance has previously been shown to reside with the ribosomes, making cytoplasmic protein synthesis refractile to the action of the drug. we show here that cycloheximide in the mutant strain causes specific alterations in metabolism without influencing the growth rate. these are: 1. lowered specific activity of glutamate dehydrogenase during starvation, 2. alteration of th ... | 1980 | 7436663 |
| calcium accumulation in vacuoles of physarum polycephalum following starvation. | the plasmodium of physarum polycephalum contained 15.3 mmol ca/kg fresh weight of sample, 11.8 mmol mg/kg, 24.5 mmol k/kg and 1.4 mmol na/kg. when the plasmodium was starved of food, the ca content increased gradually up to 71.9 mmol/kg during 5 days of starvation. the concentration of other elements changed only slightly. the endoplasm contained 23.0 mmol ca/kg, 12.6 mmol mg/kg, 26.6 mmol k/kg and 1.7 mmol na/kg, but these contents changed only slightly during starvation. the ca, mg, k and na c ... | 1980 | 7440659 |
| influence of different freeze-fracture pretreatments on the fine structure of physarum polycephalum. a freeze-fracture and freeze-substitution study. | the influence of different fixatives (glutaraldehyde, osmium, osmium/glutaraldehyde, and osmium/mercuric chloride) and freeze-protecting agents (glycerol and sucrose) on the fine-structural preservation of micro- and macroplasmodia of the acellular slime mold physarum polycephalum was investigated in both freeze-substituted and freeze-fractured material. glutaraldehyde fixation and subsequent infiltration with glycerol or sucrose caused severe destruction in the morphology of plasmodial strands ... | 1980 | 7449775 |
| in vitro assembly of microtubule proteins from myxamoebae of physarum polycephalum. | | 1980 | 7449843 |
| identification and characterization of microtubule proteins from myxamoebae of physarum polycephalum. | cell extracts of myxamoebae of physarum polycephalum have been prepared in such a way that they do not inhibit assembly of brain microtubule protein in vitro even at high extract-protein concentration. co-polymers of these extracts and brain tubulin have been purified to constant stoichiometry and amoebal components identified by radiolabelling. amoebal tubulin has been identified as having an alpha-subunit, mol.wt. 54 000, which co-migrates with brain alpha-tubulin and a beta-subunit, mol.wt. 5 ... | 1980 | 7458914 |
| a family of inverted repeat sequences and specific single-strand gaps at the termini of the physarum rdna palindrome. | ribosomal genes of physarum polycephalum are located on multiple copies of an extrachromosomal, 61 kb rdna palindrome. each terminus of the palindrome consists of a nontranscribed spacer, averaging 5.4 kb in length, which includes a region of multiple inverted repeat sequences. electron microscopy of denatured and reannealed termini reveals foldback segments that are multiples of a unit length of 50 bp, a length confirmed by sizing of restriction fragments from labeled termini. the total length ... | 1980 | 7460016 |
| contraction rhythm in the plasmodium of physarum polycephalum: dependence of the period on the amplitude, temperature and chemical environment. | the plasmodium of physarum polycephalum exhibits a characteristic protoplasmic shuttle streaming and generates periodical tension. we determined the factors which govern the period of the contraction rhythm by measuring isometric tension of the plasmodial strand and the motive force of the protoplasmic streaming under a variety of conditions by changing the size of plasmodia, chemical composition of environment and surrounding temperatures. the results are: (1) the period of contraction rhythm, ... | 1980 | 7460967 |
| two groups of deoxyribonucleic acid polymerases from physarum polycephalum classified by differential sensitivity to n-ethylmaleimide, heparin, cytosine arabinoside triphosphate and ethidium bromide: evidence for a beta-like activity. | | 1980 | 7461124 |
| nucleic acids and related enzymes. secretion of four alkaline dnases by plasmodia of physarum polycephalum. | in plasmodia of physarum polycephalum, dnase activity with a preference for native dna was found in a pattern of three or four isoenzymes. during growth a constant specific activity of approx. 0.3 unit of dnase activity per mg protein was found in the plasmodia, with a broad maximum during the g2-phase in the naturally synchronous flat cultures. under conditions of starvation or sclerotization, dnase activity was secreted by the plasmodia in amounts which were up to ten times higher than the int ... | 1980 | 7462201 |
| multiple effects of 5 mm sodium butyrate on physarum polycephalum macroplasmodia. | in a physarum polycephalum macroplasmodium, nuclei naturally divide synchronously. thus, it offers an opportunity to study growth and mitosis within a true organism. the effects of 5 mm sodium-butyrate on these processes have been examined. when this material is added to the culture medium during mitosis, the butyrate acts like a fixative on condensed chromosomes. during interphase, this short fatty acid stops growth and immediately inhibits dna synthesis. furthermore, it prevents differentiatio ... | 1981 | 7471173 |
| physarum polycephalum haemagglutinins: effect of nutrition on synthesis, and their possible role in nature. | the activity of haemagglutinins in plasmodia of physarum polycephalum was measured under different culture conditions. the activity was markedly increased when the plasmodia were incubated in a non-nutrient salt medium. during starvation, significant amounts of haemagglutinins were found in the slime layer on the surface of the plasmodia. an increase in activity was not observed in the presence of actinomycin d or cycloheximide. under starvation conditions, plasmodia are known to differentiate i ... | 1995 | 7496543 |
| pteridine biosynthesis and nitric oxide synthase in physarum polycephalum. | physarum polycephalum, an acellular slime mould, serves as a model system to study cell-cycle-dependent events since nuclear division is naturally synchronous. this organism was shown to release isoxanthopterin which is structurally related to tetrahydrobiopterin, a cofactor of aromatic amino acid hydroxylases and of nitric oxide synthases (noss) (ec 1.14.13.39). here, we studied physarum pteridine biosynthesis in more detail and found that high amounts of tetrahydrobiopterin are produced and no ... | 1994 | 7528004 |
| genetic organization of a linear mitochondrial plasmid (mf) that promotes mitochondrial fusion in physarum polycephalum. | the mf plasmid which promotes mitochondrial fusion in physarum polycephalum is a linear molecule with complex terminal inverted repeats (tirs). its nucleotide sequence was determined. the mf plasmid is 14,503 bp in size, and contains ten open reading frames (orfs). all of the orfs except one are encoded on the same dna strand (coding strand). the number of amino-acid residues in the putative proteins derived from the nine orfs on the coding strand are 231, 163, 640, 235, 118, 1130, 366, 309, and ... | 1994 | 7533058 |
| electroporation of physarum polycephalum. | | 1995 | 7550748 |
| microfilament dynamics: regulation of actin polymerization by actin-fragmin kinase and phosphatases. | based on the phosphorylation of the purified actin-fragmin complex, an 80 kda monomeric kinase (afk) has been isolated from physarum polycephalum. protein chemical analysis and studies involving kinase inhibitors and effectors establish that the afk is a unique kinase that cannot be classified so far in one of the conventional kinase families. the actin-fragmin kinase behaves as an "independent" kinase since its activity towards the actin-fragmin complex is apparently not regulated by the bindin ... | 1995 | 7572344 |
| large complexes of beta-poly(l-malate) with dna polymerase alpha, histones, and other proteins in nuclei of growing plasmodia of physarum polycephalum. | of the various cell types in the life cycle of physarum polycephalum, only the growing plasmodium contains the unusual polyester beta-poly(l-malate). the nuclei exhibit large complexes of this polymer with nuclear proteins, among them dna polymerase alpha, histones, and hmg-like proteins. the complexes are indicated by the results of size exclusion chromatography and chemical cross-linking with 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide hydrochloride (edc). after hydroxylaminolysis of the c ... | 1995 | 7578082 |
| plasmodium development in the myxomycete physarum polycephalum: genetic control and cellular events. | | 1995 | 7581996 |
| enhanced self-splicing of physarum polycephalum intron 3 by a second group i intron. | the third group i intron of physarum polycephalum is found at the same site in the large subunit rrna as the well-characterized intron from tetrahymena thermophila. formation of alternative structures in the rrna can inhibit self-splicing of the tetrahymena intron. we report that splicing of physarum intron 3 is also influenced by adjacent sequences. in this case, however, splicing is stimulated by the presence of a second group i intron 24 nucleotides downstream. in vitro, intron 3 self-splices ... | 1995 | 7585248 |
| accurate and efficient insertional rna editing in isolated physarum mitochondria. | rna editing is a process whereby nucleotide insertion, deletion, or base substitution results in the production of an rna whose sequence differs from that of its template. the mitochondrial rnas of physarum polycephalum are processed specifically at multiple sites by both mono- and dinucleotide insertions, as well as apparent cytidine (c) to uridine (u) changes. the precise mechanism and timing of these processing events are currently unknown. we describe here the development of an isolated mito ... | 1995 | 7585253 |
| phylogenetic conservation of modified nucleotides in the terminal loop 1 of the spliceosomal u5 snrna. | in order to study the phylogenetic conservation of modified nucleotides in the spliceosomal u5 snrna, we determined the nucleotide sequences of the u5 snrnas from the slime mold physarum polycephalum (embl data bank accession numbers: x74440 and x74441) and we identified the pseudouridine and 2'-o-methylated residues. from a comparison of all the u5 snrnas studied at the level of nucleotide modifications, we concluded that the modified nucleotides in u5 snrna can be divided into three classes ac ... | 1995 | 7599272 |
| purification of an atp-dependent actin-binding protein from a lower eukaryote, physarum polycephalum. | a novel protein with a molecular mass of 55 kda, as determined by sds-page, was purified from plasmodia of physarum polycephalum. the protein bound to actin filaments with a stoichiometry of 0.27 moles per mole of actin with an apparent dissociation constant of 4 x 10(-8) m. in the presence of atp, the protein dissociated from actin filaments. adenosine 5-(gamma-thio)triphosphate and adenyl-5'-yl imidodiphosphate also abolished the actin-binding activity of the protein, but gtp did not. because ... | 1995 | 7626047 |
| a photoreceptor with characteristics of phytochrome triggers sporulation in the true slime mould physarum polycephalum. | phytochrome is a ubiquitous photoreceptor in plants that controls a variety of responses to light, including gene expression, differential cell growth and intracellular movement of organelles. all phytochromes analysed so far are reversibly interconverted by light between an inactive and an active conformation, each of which has a different and characteristic absorbance spectrum. based on photophysiological measurements we provide evidence, that a photoreceptor with these unique properties of ph ... | 1995 | 7649293 |
| nuclear matrix of the lower eukaryote physarum polycephalum and the mammalian epithelial llc-pk1 cell line. a comprehensive investigation of different preparation procedures. | agarose-encapsulated nuclear matrix preparations of the lower eukaryote physarum polycephalum and the mammalian renal epithelial llc-pk1 cell line were analyzed after various experimental protocols with respect to the protein composition. the effect of the mode of deproteinization (2 m nacl, 0.25 m ammonium sulfate or 25 mm lithium diiodosalicylate), presence of 2-mercaptoethanol, ca2+, cu2+, chelating agents, the sequence of protein extraction and nuclease digestion, the use of rnase, the tempe ... | 1993 | 7680312 |
| biochemical and morphological characterization of the nuclear matrix during the synchronous cell cycle of physarum polycephalum. | we have investigated biochemical and ultrastructural aspects of the nuclear matrix during the naturally synchronous cell cycle of physarum polycephalum. the morphology of the in situ nuclear matrix exhibited significant cell cycle changes as revealed by electron microscopic examination, especially during the progression of nuclei through mitosis and s-phase. in mitosis the interchromatin matrix was found to be retracted to the nuclear periphery; during s-phase this interchromatin matrix graduall ... | 1993 | 7693736 |
| insertional editing in mitochondria of physarum. | rna produced from a number of genes on the mitochondrial (mt) dna of physarum polycephalum have nucleotides inserted at specific sites in their sequence. these insertions are spaced at approximately 25 nucleotide intervals and create open reading frames in mrna and functional structure in trnas and rrnas. although most of the insertions at a site are single cytidines; single uridines and certain dinucleotides containing adenosine and guanosine as well as cytidine and uridine are also occasionall ... | 1993 | 7694673 |
| homologous gene replacement in physarum. | the protist physarum polycephalum is useful for analysis of several aspects of cellular and developmental biology. to expand the opportunities for experimental analysis of this organism, we have developed a method for gene replacement. we transformed physarum amoebae with plasmid dna carrying a mutant allele, ardd delta 1, of the ardd actin gene; ardd delta 1 mutates the critical carboxy-terminal region of the gene product. because ardd is not expressed in the amoeba, replacement of ardd+ with a ... | 1995 | 7705620 |
| oligomerization state in solution of the cell cycle regulators p13suc1 from the fission yeast and p9cksphy from the myxomycete physarum, two members of the cks family. | the cks proteins (for cdc2 kinase subunit) are essential cell cycle regulators. they interact strongly with the mitotic cdc2 kinase, but the mechanism and the biological function of this association still await understanding. the oligomerization state in solution of two members of this ubiquitous protein family, the suc1 gene product from the fission yeast and the newly cloned cksphy gene product from the myxomycete physarum, was investigated by small-angle x-ray scattering (saxs) and biochemica ... | 1995 | 7729536 |
| rna editing of the coi mrna throughout the life cycle of physarum polycephalum. | editing of rna via the insertion, deletion or substitution of genetic information affects gene expression in a variety of systems. previous characterization of the physarum polycephalum cytochrome c oxidase subunit i (coi) mrna revealed that both nucleotide insertions and base substitutions occur during the maturation of this mitochondrial message. both types of editing are known to be developmentally regulated in other systems, including mammals and trypanosomatids. here we show that the coi mr ... | 1995 | 7770035 |
| characterization of npf mutants identifying developmental genes in physarum. | in physarum polycephalum, uninucleate haploid amoebae develop into macroscopic multinucleate plasmodia. wild-type, sexual development is triggered when two amoebae carrying different alleles of mata fuse to form a zygote which develops into a diploid plasmodium. mutations in the mata genetic region give rise to apogamic strains in which a single haploid amoeba can develop into a haploid plasmodium. an essential stage in both sexual and apogamic plasmodium formation is an extended cell cycle in u ... | 1995 | 7773386 |