| assay of diadenosine tetraphosphate hydrolytic enzymes by boronate chromatography. | a new procedure was described for assay of diadenosine tetraphosphate (ap4a) hydrolases based on boronate chromatography. potential reaction products, amp, adp, and atp, of the hydrolysis of ap4a were separated from residual substrate by chromatography on a boronate-derivatized cation-exchange resin, bio-rex 70. separation was achieved by changing the concentrations of ethanol and ammonium acetate in the elution buffers. picomole masses of products were detectable, blank dpm values were less tha ... | 1985 | 2984957 |
| identification of ubiquitinated histones 2a and 2b in physarum polycephalum. disappearance of these proteins at metaphase and reappearance at anaphase. | ubiquitinated histones uh2a.1, uh2a.z, and uh2b have been identified in the basic nuclear proteins of the slime mold physarum polycephalum by three methods: peptide mapping, cross-reaction with anti-ubiquitin antibody, and uh2a and uh2b isopeptidase cleavage. in microplasmodia, uh2a amounts to 7% of h2a and uh2b amounts to 6% of h2b. detailed studies of mitosis in physarum polycephalum macroplasmodia show that in early prophase, which last 15 min, the uh2as and uh2b are both strongly present, wh ... | 1985 | 2985575 |
| structural organization of a hypermethylated nuclear dna component in physarum polycephalum. | digestion of physarum polycephalum nuclear dna using the restriction endonuclease hpaii generates two components, distinguishable on the basis of their molecular size. the high-molecular-weight, hpaii-resistant component, which accounts for 20% of the dna, contains a fivefold greater concentration of 5-methylcytosine residues than the low-molecular-weight hpaii-digested fraction. segments of hypermethylated (m+) dna are largely composed of a single, long, highly repeated sequence, and this major ... | 1985 | 2991423 |
| adp-ribosyltransferase in isolated nuclei during the cell cycle of physarum polycephalum. | adp-ribosyltransferase was measured in isolated nuclei of physarum polycephalum. activity was determined with and without exogenous dna and histones. during the synchronous cell cycle the activity measured with exogenous substrates exhibited a typical peak enzyme pattern with a maximum of activity in s-phase, whereas activity measured without exogenous substrates displayed a step enzyme pattern. both activities doubled in each cell cycle. | 1985 | 3002325 |
| transient expression of a chloramphenicol acetyltransferase gene following transfection of physarum polycephalum myxamoebae. | a plasmid was constructed containing a replication origin sequence from the physarum ribosomal dna molecule, and a bacterial chloramphenicol acetyltransferase (cat) gene linked to a putative promoter of the long terminal repeat (ltr) of the physarum "hpaii-repeat" element. the plasmid was transfected into physarum myxamoebae either by electroporation or cacl2 treatment. in both cases significant transient levels of cat gene expression were detected. results were compared with those obtained with ... | 1988 | 3162844 |
| a method for isolation of nuclei containing undegraded rna from rnaase-rich plasmodia of physarum polycephalum. | (1) in order to protect the nuclear rna of physarum polycephalum plasmodia during cell homogenisation and purification of the nuclei, the following conditions were used: low temperature (-11 degrees c), high ph (8.1-8.9), formaldehyde (2.8%) and spermine (2.3 mm). (2) the efficiency of these rnaase-inhibiting and inactivating conditions is demonstrated by the high molecular weight of the processing products of transcripts from ribosomal genes (11.9, 9.5 and 5.0 kilobases), which were recovered f ... | 1988 | 3167059 |
| regulation of mitosis onset and thymidine kinase activity during the cell cycle of physarum polycephalum plasmodia: effect of hydroxyurea. | the effects of hydroxyurea have been investigated on three events of the cell cycle, s-phase, mitosis, and the cyclic synthesis of thymidine kinase, in the synchronous plasmodium of the myxomycete physarum. dna synthesis was slowed down with limited action on other macromolecular syntheses and any increase of thymidine kinase that had already been triggered was indistinguishable from that of the control. when dna synthesis was inhibited, the onset of the following cyclic increase of thymidine ki ... | 1988 | 3169145 |
| selective gene expression during sporulation of physarum polycephalum. | the two-dimensional gel electrophoresis of polypeptides synthesized in vitro from poly(a)+ rna showed that mrna populations change during sporulation of physarum polycephalum. the differential hybridization of a cdna library prepared from poly(a)+ rna isolated from sporulating cells revealed that of 846 clones, 64 corresponded to sporulation-specific mrnas. further analysis demonstrated that these clones contained seven different sequences: three abundant sequences composing 3.2, 1.8, and 1.2% o ... | 1988 | 3170484 |
| structure and expression of an actin gene of physarum polycephalum. | physarum polycephalum (strain m3cviii) contains four unlinked actin gene loci, each with two alleles (arda1, arda2, ardb1, ardb2, ardc1, ardc2, ardd1 and ardd2). the 4800 base hindiii fragment of the ardc2 allele was previously isolated as a recombinant phage lambda. we now report the structure of the actin gene sequences (c-actin gene). the gene, which contains four intervening sequences, codes for the principal actin isotype of plasmodia and it is expressed in both the haploid myxamoebal and d ... | 1988 | 3172209 |
| phosphohistidine is found in basic nuclear proteins of physarum polycephalum. | nuclear extracts of the true slime mold, physarum polycephalum, show protein histidine kinase activity towards exogenous histones [(1985) j. biol. chem. 260, 16106-16113]. physarum microplasmodia were labeled with [32p]phosphate in vivo and two basic proteins containing alkali-stable phosphate were detected. the labeled proteins comigrated with physarum histones h1 (approximately) and h2a and phosphoamino acid analysis showed that each protein contained [32p]-phosphohistidine. the h2a-like prote ... | 1988 | 3181421 |
| nucleotide sequence of the physarum polycephalum small subunit ribosomal rna as inferred from the gene sequence: secondary structure and evolutionary implications. | the nucleotide sequence of the physarum polycephalum small subunit ribosomal rna (ssu rrna) gene has been determined. sequence data indicate that the mature 19s ssu rrna is 1,964 nucleotides long. a complete secondary structure model for p. polycephalum ssu rrna has been constructed on the basis of the escherichia coli 16s rrna model and data from comparative analyses of 28 different eukaryotic sequences. a "four-helix" model is presented for the central domain variable region. this model can be ... | 1988 | 3197135 |
| activation of a beta-tubulin gene during early development of the plasmodium in physarum polycephalum. | uninucleate amoebae of physarum polycephalum strain cl undergo apogamic development to form multinucleate plasmodia via an intermediate stage of large, uninucleate cells irreversibly committed to plasmodial development. this amoebal-plasmodial transition involves major changes in tubulin gene expression and the organization of microtubular structures. we analysed the expression of the betc locus, which encodes the plasmodial-specific beta 2-tubulin, during plasmodial development. a key question ... | 1988 | 3199099 |
| assembly, disassembly, and movements of the microfilament-rich ridge during the amoeboflagellate transformation in physarum polycephalum. | the amoeboflagellate transformation in physarum polycephalum involves a series of dramatic changes in cell shape and motile behavior. this report describes the morphological and behavioral changes through which a synchronously transforming population of cells passes, stressing that, although there are a series of distinguishable stages, cells at all stages display striking plasticity. our previous studies showed that amoeboflagellates transiently display a flattened motile extension--the ridge-- ... | 1988 | 3219731 |
| methylation is co-ordinated on the putative replication origins of physarum ribosomal dna. | in physarum polycephalum, the ribosomal dna is found as 60,000 base-pair palindromes. each rdna has four symmetrically arranged replication origins flanked by ribosomal rna genes. a particular sequence, the putative replication origin, is repeated at the approximate position of each origin and nowhere else in the molecule. on a typical rdna molecule, only one origin is active per replication cycle. we show that both the level and co-ordination of methylation result in asymmetrically methylated r ... | 1988 | 3221398 |
| nucleotide sequence of the central non-transcribed spacer region of physarum polycephalum rdna. | in physarum polycephalum the rrna genes are present on linear extrachromosomal molecules, each containing two transcription units arranged as a giant palindrome. in the center of the molecule, between the two transcription units, is the 23-kb central spacer, previously shown to contain the replication origins and several regions of direct and inverted repeats. segments of all the repeats in the spacer have been sequenced and their overall organization determined. the entire spacer consists of re ... | 1985 | 3005112 |
| processing in the external transcribed spacer of ribosomal rna from physarum polycephalum. | the rdna of the myxomycete physarum polycephalum is transcribed to give a 13.3 kb precursor of ribosomal rna. at 1.7 kb downstream of the primary initiation site there is a processing site or a second initiation site. this site was studied by s1-mapping, dna sequencing and electron microscopy. none of these methods could conclusively distinguish between the two formal possibilities. however, capping experiments indicate that rapid processing is taking place at this site rather than reinitiation. ... | 1986 | 3010228 |
| two-dimensional gel analysis of repetitive nuclear dna sequences in the genome of physarum polycephalum. developmental regulation of the ribosomal gene number. | the composition of repetitive sequences in restriction patterns of nuclear dna of physarum polycephalum was determined by high-resolution gel analysis. three types of repeated dna fragments in the size range of (0.2-2) x 10(3) base pairs could be identified as discrete spots on the gels and distinguished by their abundance and above-average base composition of either guanine and cytosine (g + c) or adenine and thymidine (a + t). on comparing the dna composition from exponentially growing plasmod ... | 1986 | 3013633 |
| three diadenosine 5',5''-p1,p4-tetraphosphate hydrolytic enzymes from physarum polycephalum with differential effects by calcium: a specific dinucleoside polyphosphate pyrophosphohydrolase, a nucleotide pyrophosphatase, and a phosphodiesterase. | two new enzymes that hydrolyze diadenosine tetraphosphate (ap4a) have been isolated from the acellular slime mold physarum polycephalum. both enzymes are different from the physarum ap4a symmetrical pyrophosphohydrolase previously described on the basis of their substrate specificities, reaction products, molecular weights, and divalent cation requirements. one enzyme is a nucleotide pyrophosphatase that asymmetrically hydrolyzes ap4a to amp and atp. this enzyme hydrolyzes several mono- and dinu ... | 1986 | 3017212 |
| differential gene expression during the amoebal-plasmodial transition in physarum. | we have prepared cdna libraries for amoebae and plasmodia of the acellular slime mould, physarum polycephalum. differential screening was used to isolate cell-type-specific cdna clones (in bacteriophage m13) and both libraries yielded approximately 5% of such sequences. the amoebal- and plasmodial-specific clones were used to assay changes in transcription during the amoebal-plasmodial transition. the results obtained substantiate the view that the switch from amoebal to plasmodial characteristi ... | 1987 | 3029710 |
| microtubule cytoskeleton and morphogenesis in the amoebae of the myxomycete physarum polycephalum. | the amoebae of the myxomycete physarum polycephalum are of interest in order to analyze the morphogenesis of the microtubule and microfilament cytoskeleton during cell cycle and flagellation. the amoebal interphase microtubule cytoskeleton consists of 2 distinct levels of organization, which correspond to different physiological roles. the first level is composed of the 2 kinetosomes or centrioles and their associated structures. the anterior kinetosomes forming the anterior and posterior flagel ... | 1988 | 3060203 |
| in situ preparation of the nuclear matrix of physarum polycephalum: ultrastructural and biochemical analysis of different matrix isolation procedures. | a novel method for in situ preparation of nuclear matrix from whole plasmodia of physarum polycephalum without isolation of nuclei is presented. plasmodia are encapsulated in agarose beads and after solubilization of the cytoplasm the nuclear matrix is prepared. with this quick and easy technique nuclear matrix can be reproducibly prepared with perfect recovery. we compared the ultrastructural and biochemical properties of the matrix after three different matrix isolation procedures: preparation ... | 1988 | 3075619 |
| effects of low temperature and calcium on microfilament structure in flagellates of physarum polycephalum. | microfilament structures of the ridge and the backbone in physarum flagellates disintegrated selectively within a few minutes upon cooling by ice-water. the elongated cells concurrently rounded up to spherical or irregular and amoeboid shape. when such rounded cells were warmed to 25 degrees c, the microfilament structures were reconstructed within 1 min and cells subsequently returned to an elongated shape. disruption of microfilaments by cytochalasin a also caused the rounding up of cells, ind ... | 1986 | 3087763 |
| nuclear matrix proteins of physarum polycephalum. | the proteins of nuclear matrix preparations from physarum polycephalum were compared with analogous mammalian fractions by gel electrophoresis, dna-binding studies and immunological tests. polypeptides of 28 and 36 k dalton, which dominate in physarum preparations, differed from calf thymus matrix proteins in that they were basic and showed low affinity to dna. these polypeptides were present at about 1.2 mg per mg of nuclear dna. polypeptides of higher molecular weight occurred in the preparati ... | 1986 | 3100943 |
| histone synthesis during the cell cycle of physarum polycephalum. synthesis of different histone species is not under a common regulatory control. | the synthesis of histones and nonhistone nuclear proteins was studied during the naturally synchronous cell cycle of physarum polycephalum. contrary to the commonly accepted idea of a tight coupling of histone biosynthesis and dna replication during the somatic cell cycle we found that 40% of total histone synthesis takes place in the g2 period in the complete absence of dna synthesis. the core histones exhibit a maximum of synthesis during s-phase. the synthesis of histones h2a and h2b continue ... | 1987 | 3112137 |
| dna synthesis in isolated nuclei from synchronized plasmodia of physarum polycephalum. | nuclei were isolated from synchronized plasmodia of a true slime mold, physarum polycephalum, in s-phase, and dna synthesis in the nuclei was studied in vitro. the nuclei catalyzed dna synthesis at the rate of 0.7 ng dna/1.0 x 10(6) nuclei/30 min at 25 degrees c, which was 5 times higher than that catalyzed in g2-phase nuclei. the dna synthesis required mg2+, four kinds of deoxyribonucleoside 5'-triphosphates and atp, suggesting that the mode of synthesis is a replicative-type, but not a repair- ... | 1987 | 3113747 |
| immunoquantitation and size determination of intrinsic poly(adp-ribose) polymerase from acid precipitates. an analysis of the in vivo status in mammalian species and in lower eukaryotes. | antibodies against pig thymus poly(adp-ribose) polymerase were obtained with enzyme-hemocyanin conjugates and used for immunoquantitation. the quick-blot procedure used allowed the determination of amounts as low as 1 ng of enzyme from whole cell trichloracetic acid precipitates. when applied to analysis of various human, rodent, and bovine cell types, surprisingly similar amounts of polymerase were found (1-5 ng of pig thymus polymerase equivalents/micrograms of dna, 2 x 10(5) polymerase molecu ... | 1988 | 3130376 |
| adp-ribosylation in isolated nuclei of physarum polycephalum. | adp-ribosylation of histones and non-histone nuclear proteins was studied in isolated nuclei during the naturally synchronous cell cycle of physarum polycephalum. aside from adp-ribosyltransferase (adprt) itself, histones and high mobility group-like proteins are the main acceptors for adp-ribose. the majority of these adp-ribose residues is nh2oh-labile. adp-ribosylation of the nuclear proteins is periodic during the cell cycle with maximum incorporation in early to mid g2-phase. in activity ge ... | 1988 | 3140789 |
| the nucleolar protein, b-36, contains a glycine and dimethylarginine-rich sequence conserved in several other nuclear rna-binding proteins. | the amino terminal sequence of the 34 kd nucleolar protein b-36 isolated from the slime mold physarum polycephalum has been determined. this portion of b-36 is rich in glycine, phenylalanine and the modified amino acid asymmetrical dimethylarginine (dma) and is 65% identical to that for fibrillarin, a similar and potentially homologous 34 kd nucleolar protein from rat. the terminus of b-36 contains an interesting nine amino acid sequence, gly-dma-gly-gly-phe-gly-gly-dma-gly, which is precisely r ... | 1988 | 3140806 |
| amphibian oocyte maturation induced by extracts of physarum polycephalum in mitosis. | the orderly progression of eukaryotic cells from interphase to mitosis requires the close coordination of various nuclear and cytoplasmic events. studies from our laboratory and others on animal cells indicate that two activities, one present mainly in mitotic cells and the other exclusively in g1-phase cells, play a pivotal role in the regulation of initiation and completion of mitosis, respectively. the purpose of this study was to investigate whether these activities are expressed in the slim ... | 1988 | 3286658 |
| biosynthesis and activity of dna polymerase throughout the mitotic cycle of physarum polycephalum. | measurements of dna polymerase protein levels and polymerase activity through the naturally synchronous mitotic cycle of physarum polycephalum show that active dna polymerase-alpha is synthesized throughout the g2 phase, in step with the profile of general protein biosynthesis. three main components of p. poly-cephalum dna polymerase of 200, 112 and 70 kda were found to be immunologically related. | 1987 | 3305076 |
| amino acid sequence of the calcium-binding light chain of myosin from the lower eukaryote, physarum polycephalum. | we have established a new method for preparing physarum myosin whose actin-activated atpase activity is inhibited by micromolar levels of ca2+. this ca2+-inhibition is mediated by the ca2+ binding to the myosin rather than by the ca2+-dependent modification of the phosphorylated state of the myosin (kohama, k., and kendrick-jones, j. (1986) j. biochem. (tokyo) 99, 1433-1446). ca2+-binding light chain (calc) has been suggested to be primary importance in this ca2+ inhibition (kohama, k., takano-o ... | 1988 | 3335500 |
| superoxide dismutase induces differentiation in microplasmodia of the slime mold physarum polycephalum. | evidence is presented that supports a role for the enzyme superoxide dismutase (sod) in the differentiation of the slime mold, physarum polycephalum. sod activity increases 46-fold during differentiation. a strain of physarum that does not differentiate exhibits no change in sod activity. addition of sod, via liposomes, to the nondifferentiating strain induces differentiation; this effect is enhanced by an inhibitor of glutathione synthesis. other antioxidants selected for study failed to induce ... | 1988 | 3341774 |
| low frequency electric and magnetic fields have different effects on the cell surface. | there is a considerable controversy over the nature of weak electromagnetic-field effects in living organisms. part of the controversy can be traced to a lack of understanding of whether electric or magnetic fields are involved in producing bioeffects. we find that both 60 hz electric and magnetic fields alter the cell surface of physarum polycephalum. exposure to electric fields increases the negative charge on the cell surface while magnetic-field exposure decreases the hydrophobic character o ... | 1988 | 3350147 |
| correlation between tubulin mrna stability and poly(a) length over the cell cycle of physarum polycephalum. | during the cell cycle of the physarum polycephalum plasmodium, levels of alpha-tubulin mrna rise exponentially in g2 phase, reach a peak at metaphase 40-fold above basal levels, and then fall exponentially to basal levels after mitosis. we show that post-mitotic alpha-tubulin mrna carries poly(a) tracts of less than 30 residues. by contrast, when levels of alpha-tubulin mrna rise during g2 phase, the mrna has a poly(a) tract of approximately 80 bases. the length of the poly(a) tract of any mrna ... | 1988 | 3373532 |
| histone h4 mrna is stored as a small cytoplasmic rnp during the g2 phase in physarum polycephalum. | in physarum polycephalum the triggering of histone h4 gene transcription occurs in g2 phase. the rate of synthesis of histone h4 mrna was measured by in vivo pulse-labeling experiments. we show that it begins to increase in mid-g2. during the second part of g2 it increases approximately 20 fold over its minimum value and reaches a maximum at the end of g2. after entry of the cells in s, histone h4 gene transcription rate begins to decrease and reaches a minimum value in early g2. the histone h4 ... | 1988 | 3377784 |
| histone phosphorylation during repression of proliferation in a lower eucaryote physarum polycephalum. | nutrient depletion causes a rapid drop in transcription and completely inhibits dna replication in plasmodia of a slime mold physarum polycephalum. these events are accompanied by progressive dephosphorylation of histone h3 and no change in the state of phosphorylation of the bulk of histone h1. this shows that the compaction of chromatin associated with transcriptional inactivation does not require phosphorylation of h3 and suggests that the level of basal phosphorylation of h1 is not correlate ... | 1988 | 3382385 |
| cloning and expression of a beta tubulin gene of physarum polycephalum. | a beta tubulin gene of physarum polycephalum has been isolated from a genomic library in the phage embl4. southern-blot hybridization to genomic dna indicates that the cloned dna is derived from the betb1 locus of the beta tubulin gene family. a tubulin-specific subfragment of the phage dna was used as a hybridization probe to construct a restriction map of the betb1 locus. the probe consisted of the almost complete coding region of the 5' half of the tubulin gene, interrupted by one intron. the ... | 1988 | 3391166 |
| the purification of ribosomal rna gene chromatin from physarum polycephalum. | we have undertaken the purification of ribosomal rna gene (rdna) chromatin from the slime mold physarum polycephalum, in order to study its chromatin structure. in this organism rdna exists in nucleoli as highly repeated minichromosomes, and one can obtain crude chromatin fractions highly enriched in rdna from isolated nucleoli. we first developed a nucleolar isolation method utilizing polyamines as stabilization agents that results in a chromatin fraction containing far more protein than is obt ... | 1988 | 3392038 |
| identification of ecorv fragments spanning the n alpha-tubulin gene of physarum. | the n alpha-tubulin gene of physarum polycephalum has an ecorv site at codons 252/253. ecorv digestion of physarum dna generated two ecorv fragments per gene copy comprising both coding and flanking sequences. hybridisation probes which included coding sequences upstream from the central ecorv site cross-hybridised with another alpha-tubulin gene. probes derived from either 5'- or 3'-flanking regions were gene-specific. these probes identified two ecorv fragments in the haploid strain cldaxe viz ... | 1988 | 3264251 |
| the characterization of ribosomal rna gene chromatin from physarum polycephalum. | we have isolated ribosomal rna gene (rdna) chromatin from physarum polycephalum using a nucleolar isolation procedure that minimizes protein loss from chromatin and, subsequently, either agarose gel electrophoresis or metrizamide gradient centrifugation to purify this chromatin fraction (amero, s. a., ogle, r. c., keating, j. l., montoya, v. l., murdoch, w. l., and grainger, r. m. (1988) j. biol. chem. 263, 10725-10733). metrizamide-purified rdna chromatin obtained from nucleoli isolated accordi ... | 1988 | 3392039 |
| the secondary structure of large-subunit rrna divergent domains, a marker for protist evolution. | the secondary structure of the large-subunit ribosomal rna (24-26s rrna) has been studied with emphasis on comparative analysis of the folding patterns of the divergent domains in the available protist sequences, that is prorocentrum micans (dinoflagellate), saccharomyces carlsbergensis (yeast), tetrahymena thermophila (ciliate), physarum polycephalum and dictyostelium discoideum (slime moulds), crithidia fasciculata and giardia lamblia (parasitic flagellates). the folding for the d3, d7a and d1 ... | 1988 | 3395681 |
| expression of the three unlinked isocoding actin genes of physarum polycephalum. | the actin gene family in physarum polycephalum contains four unlinked loci: arda, ardb, ardc, and ardd. the arda locus is complex and probably contains two genes which we designated arda2-7 and arda2-17. cdna clones corresponding to the ardb and ardc loci were isolated. nucleic acid sequencing showed that these two cdnas coded for the only abundant form of physarum actin, which is 96% homologous to human gamma-cytoplasmic actin. the arda2-17 gene also codes for this same actin protein (nader et ... | 1988 | 3402310 |
| phalloidin-gold complexes: a new tool for ultrastructural localization of f-actin. | we used a phalloidin-gold complex to study the distribution of f-actin in the myxamoebae and macroplasmodia of the slime mold physarum polycephalum. after incubation of lowicryl- or quetol-embedded specimens with this complex, significantly different labeling intensities were found over the various cytoplasmic and nuclear regions of the cells. the nucleoplasm was the most heavily labeled cell compartment, followed in decreasing order of labeling intensity by the cytoplasm, the nucleolus, and the ... | 1988 | 3403970 |
| isolation and sequencing of alpha-tubulin peptides from myxamoebae of the slime mould physarum polycephalum. | starting from only 5.9 mg of alpha-tubulin from myxamoebae of the slime mould physarum polycephalum, we have isolated and sequenced peptides that account for 96% of the complete sequence. the peptides were generated by digestion of alpha-tubulin with trypsin, staphylococcus aureus protease and cyanogen bromide. they were then separated according to size on a tsk g2000 sw column using a 10 mm ammonium acetate buffer at ph 6.8. in addition to good peptide separations, a time-consuming desalting st ... | 1987 | 3555622 |
| a method for separation of pigments from plasmodia of the true slime molds, physarum polycephalum and physarum nudum. | plasmodia of the true slime molds physarum polycephalum and physarum nudum were grown on agar semidefined medium (j. w. daniel and h. baldwin (1964) in methods in cell physiology (precsott, d. m., ed.), vol. 1, pp. 9-44, academic press, new york.) and pigments were extracted from 8-day-old plasmodia with the same solvent mixture that was used later as a mobile phase in the hplc analysis. the separation was carried out on a strong anion exchanger column in a methanol/borate buffer solution. under ... | 1987 | 3565750 |
| cell-cycle-regulated translation of histone mrna in physarum plasmodia. | in physarum polycephalum, histone mrna begins to accumulate 3 h before the s phase. we show that histone synthesis was limited to the s phase and that the mrna that accumulated in the g2-phase cytoplasm could be translated in vitro. thus, recruitment of stored mature histone mrna did not occur until the s phase began. | 1987 | 3571168 |
| translational control and the cytoskeleton in physarum polycephalum. | translationally active plasmodia of the syncytial slime mold physarum polycephalum develop into translationally dormant sclerotia during starvation. although functional mrna and ribosomes exist in sclerotia, protein synthesis is suppressed at the level of initiation. to test the possibility that alterations in the cytoskeleton may limit protein synthesis, we have examined the distribution of polysomes and actin mrna in the cytoskeletal (csk) and soluble (sol) fractions of triton x-100-extracted ... | 1987 | 3581185 |
| altered nucleosomes of active nucleolar chromatin contain accessible histone h3 in its hyperacetylated forms. | chromatin of the organism physarum polycephalum contains a class of conformationally altered nucleosomes previously localized to the transcribing regions of ribosomal genes in nucleoli. when nuclei are treated with 2-iodo[2-tritium]acetate, the histone h3 sulfhydryl group of the altered nucleosomes is derivatized while that of folded nucleosomes is not, and the labeled histones can then be identified by autoradiography of gels that separate h3 isoforms. the h3 derivatized is predominantly of tri ... | 1987 | 3584101 |
| amino acid sequence data of alpha-tubulin from myxamoebae of physarum polycephalum. | about 96% of the amino acid sequence of an alpha-tubulin from the slime mould physarum polycephalum has been determined. of 430 sequenced amino acids, 30 differ from the deduced amino acid sequence of a recently published alpha-tubulin complementary dna from the plasmodial form of p. polycephalum. the myxamoebal alpha-tubulin differs from all other known alpha-tubulins in one of the last three c-terminal amino acids that are gly-glu-tyr instead of the usual glu-glu-tyr. these last three amino ac ... | 1986 | 3586014 |
| primary structure of an alpha-tubulin gene of physarum polycephalum. | an alpha-tubulin gene of physarum was isolated as a phage-lambda nm1149 recombinant (designated phage-lambda n alpha tu). phage-lambda n alpha tu contained a 4700 base-pair hindiii nuclear dna fragment of an allele of the altb locus of physarum (one of four unlinked alpha-tubulin gene loci). subfragments of the 4700 base-pair insert of phage-lambda n alpha tu were cloned into phage m13 and the nucleotide sequence was determined by the dideoxy chain termination method. the start point of transcri ... | 1987 | 3586027 |
| periodic fluctuations of nuclear high mobility group like proteins during the cell cycle of physarum polycephalum. | high mobility group like (hmg-like) nuclear proteins were isolated from plasmodia of the lower eucaryote physarum polycephalum and characterized by different types of polyacrylamide gel electrophoresis. the synthesis of these proteins was measured during the naturally synchronous cell cycle of physarum. the four hmg-like proteins (as1-4) exhibit a pronounced cell cycle dependent pattern of synthesis: as1 and as4 have a clear maximum of synthesis in mid s phase with a basal synthesis during the e ... | 1988 | 3415977 |
| purification and characterization of dna polymerase alpha from plasmodia of physarum polycephalum. | dna polymerase alpha from physarum polycephalum has been purified from freshly harvested microplasmodia. an inhibitory activity was removed by precipitation with poly(ethyleneimine) and interfering type-beta-like dna polymerase by chromatography on phosphocellulose. the preparation was free of endonucleases and exonucleases. the dna-polymerizing polypeptide had a molecular mass of 140 kda by polyacrylamide gel electrophoresis under denaturing conditions. it was contained in purified samples and ... | 1988 | 3416868 |
| identification of an autonomously replicating sequence near a histone gene of physarum polycephalum. | fragments of dna which function as autonomous replication sequences in yeast were cloned from physarum polycephalum. the ars activity is located in a 1.2 kbp fragment extending 1.5 kbp to 2.7 kbp upstream of the 5' end of a histone h4 gene. our recent finding that a replication origin is located at a distance less than 3 kbp of this histone gene suggests that the ars element identified coincides with a specialized replication origin and can be used to direct chromosome replication in physarum po ... | 1986 | 3442825 |
| tubulin isotypes: generation of diversity in cells and microtubular organelles. | diversity of tubulin isotypes is illustrated by consideration of the beta-tubulin isotypes of higher plants and the eukaryotic microbe, physarum polycephalum, and by the alpha-tubulin isotypes of the protozoan, trypanosoma brucei. the carrot plant expresses six, well-defined beta-tubulin isotypes that possess characteristic two-dimensional gel coordinates. these six beta-tubulin isotypes are differentially expressed during development of the flowering plant. in a similar manner, physarum express ... | 1986 | 3477554 |
| analysis of the internal nuclear matrix. oligomers of a 38 kd nucleolar polypeptide stabilized by disulfide bonds. | when rat liver nuclei are treated with the sulfhydryl cross-linking reagent sodium tetrathionate (natt) prior to nuclease treatment and extraction with 1.6 m nacl, residual nucleoli and an extensive non-chromatin intranuclear network remain associated with the nuclear envelope. subsequent treatment of this structure with 1 m nacl containing 20 mm dithiothreitol (dtt) solubilizes the intranuclear material, while the nuclear envelope remains structurally intact. we have isolated and partially char ... | 1986 | 3514251 |
| amino-acid sequence data of beta-tubulin from physarum polycephalum myxamoebae. | starting with 7.7 mg of a beta-tubulin isolated from myxamoebae of the slime mould physarum polycephalum, 90% of the sequence has been determined by the edman degradation of peptides generated by cyanogen bromide, trypsin and staphylococcus aureus protease. differences to other beta-tubulins are mainly conservative and spread evenly throughout the chain except for a high concentration at the c-terminus. the physarum beta-tubulin shows most homology to chlamydomonas beta-tubulin (90.5%) and least ... | 1986 | 3539596 |
| acetylated alpha-tubulin in physarum: immunological characterization of the isotype and its usage in particular microtubular organelles. | we have used monoclonal antibodies specific for acetylated and unacetylated alpha-tubulin to characterize the acetylated alpha-tubulin isotype of physarum polycephalum, its expression in the life cycle, and its localization in particular microtubular organelles. we have used the monoclonal antibody 6-11b-1 (piperno, g., and m. t. fuller, 1985, j. cell biol., 101:2085-2094) as the probe for acetylated alpha-tubulin and have provided a biochemical characterization of the monoclonal antibody kmp-1 ... | 1987 | 3539947 |
| effects of sinusoidal 60-hz electric and magnetic fields on atp and oxygen levels in the slime mold, physarum polycephalum. | we have previously reported that exposing the vegetative plasmodia stage of physarum polycephalum to either individual or simultaneously applied electric and magnetic fields (45-75 hz, 0.14-2.0 g, and 0.035-0.7 v/m) lengthens their mitotic cycle, depresses their rate of reversible shuttle streaming, and lowers their respiration rate. in this article we report the effects of simultaneously applied electromagnetic fields (60 hz, 1.0 g, 1.0 v/m), electric fields only (60 hz, 1.0 v/m), magnetic fiel ... | 1986 | 3753533 |
| widespread occurrence of anti-troponin t crossreactive components in non-muscle cells. | using a monoclonal antibody generated against striated muscle troponin t, we previously noted the presence of crossreactive components in smooth muscle and non-muscle cells. since the presence of troponin t in tissues other than striated muscle is controversial, we sought to establish the nature of the crossreaction and to determine the extent of its occurrence. for this study, indirect immunofluorescence microscopy and immunoblot analyses were performed. crossreactive material was found in dive ... | 1986 | 3539951 |
| distribution of acetylated alpha-tubulin in physarum polycephalum. | the expression and cytological distribution of acetylated alpha-tubulin was investigated in physarum polycephalum. a monoclonal antibody specific for acetylated alpha-tubulin, 6-11b-1 (piperno, g., and m. t. fuller, 1985, j. cell biol., 101:2085-2094), was used to screen for this protein during three different stages of the physarum life cycle--the amoeba, the flagellate, and the plasmodium. western blots of two-dimensional gels of amoebal and flagellate proteins reveal that this antibody recogn ... | 1987 | 3543025 |
| myosin switching during amoebo-plasmodial differentiation of slime mold, physarum polycephalum. | we reported previously that myosins from amoebal and plasmodial stages in the life cycle of physarum polycephalum differ in the primary structure of heavy chains and phosphorylatable 18,000 mr light chains, while ca-binding 14,000 mr light chains are common to both myosins (kohama & takano-ohmuro, proc jpn acad 60b (1984) 431; kohama et al., j biol chem 260 (1986) 8022). we have carried out immunofluorescence microscopical studies upon differentiating cultures of amoebic colonies, which show apo ... | 1987 | 3545862 |
| histone acetyltransferase activity during the cell cycle. | histone acetyltransferase activity was measured in isolated nuclei during the synchronous cell cycle of the myxomycete physarum polycephalum. nuclei were incubated with [14c]acetyl-coenzyme a and an excess of exogenous calf thymus histones. the activity is periodic during the cell cycle; it rises during the s-phase to reach a maximum in the early g2-period with a decline in mid and late g2. comparison of the pattern of enzyme activity with the in vivo acetylation of histones during the cell cycl ... | 1987 | 3653410 |
| superoxide dismutase activity and glutathione concentration during the calcium-induced differentiation of physarum polycephalum microplasmodia. | microplasmodia of physarum polycephalum differentiate into spherules when the cacl2 concentration of their nutrient medium is increased to 54mm (high-calcium). the salts starvation medium routinely used to induce differentiation contains 8mm cacl2. this medium will not induce spherulation in the absence of a calcium salt; no other metal is essential. high-calcium also induces the spherulation of a strain of physarum that had not been previously observed to spherulate. the striking increase in su ... | 1987 | 3667705 |
| fatty acid acylation of proteins in physarum polycephalum. | we have investigated the occurrence of protein-fatty acid acylation by metabolic incorporation of [3h]myristic and [3h]palmitic acids in physarum polycephalum. we show that this organism contains fatty acylated proteins with mainly myristic acid covalently attached in alkali-stable linkages, probably amides. we find no evidence for ester-linked fatty acids, in contrast to the situation in vertebrate cells. | 1987 | 3677177 |
| patterns of tubulin isotype synthesis and usage during mitotic spindle morphogenesis in physarum. | tubulin synthesis in the naturally synchronous plasmodium of physarum polycephalum is a markedly periodic event restricted to the late g2 period of the cell cycle. mitosis in the plasmodium is intranuclear, and there are no cytoplasmic microtubules at any stage of the cell cycle. we have combined a biochemical investigation of the synthesis of the plasmodial tubulin isotypes and their participation in the mitotic spindle with a microscopic study (immunofluorescence) of the development of spindle ... | 1987 | 3594580 |
| negative control of periodic tubulin gene expression in the mitotic cycle of physarum polycephalum. | naturally synchronous syncytial plasmodia of physarum polycephalum provide an ideal model for studying the eukaryotic cell cycle. the tubulin genes of physarum provide a striking example of cell cycle-regulated gene expression: synthesis of both tubulin mrna and the tubulin proteins is limited to the last three hours of g2 phase. fusion of late g2-phase plasmodia, in which the tubulin genes are actively expressed, and mid-s phase plasmodia, in which the tubulin genes are not expressed, is used t ... | 1987 | 3595631 |
| distinct replication-independent and -dependent phases of histone gene expression during the physarum cell cycle. | during the s phase of the cell cycle, histone gene expression and dna replication are tightly coupled. in mitotically synchronous plasmodia of the myxomycete physarum polycephalum, which has no g1 phase, histone mrna synthesis begins in mid-g2 phase. although histone gene transcription is activated in the absence of significant dna synthesis, our data demonstrate that histone gene expression became tightly coupled to dna replication once the s phase began. there was a transition from the replica ... | 1987 | 3600651 |
| both histone h4 genes of physarum polycephalum are interrupted by an intervening sequence. | | 1987 | 3601677 |
| selective inhibition of dna polymerase alpha by a polysaccharide purified from slime of physarum polycephalum. | a polysaccharide was purified from the slime of a myxomycete, physarum polycephalum, and its inhibitory effect on eukaryotic dna polymerases was examined. almost all the calf thymus dna polymerase alpha activity was inhibited with higher than 0.2 mg/ml of the polysaccharide, when the assay was carried out with activated dna as a template. the inhibitory effect occurred regardless of the amounts of the enzyme and deoxyribonucleotides, however, kinetic analysis revealed that the inhibition occurs ... | 1987 | 3606625 |
| dynamic aspects of the contractile system in physarum plasmodium. iii. cyclic contraction-relaxation of the plasmodial fragment in accordance with the generation-degeneration of cytoplasmic actomyosin fibrils. | plasmodial fragments of physarum polycephalum, excised from anterior regions of a thin-spread plasmodium, contracted-relaxed cyclicly with a period of 3-5 min. the area of the fragments decreased approximately 10% during contraction. in most cases, there was little endoplasmic streaming which indicates that contractions were synchronized throughout the fragment. by both polarized light and fluorescence microscopy, the organization and distribution of the cytoplasmic actomyosin fibrils in the fra ... | 1987 | 3611192 |
| calcium sensitivity of cytoplasmic actomyosin from physarum polycephalum following different purification procedures. | cytoplasmic actomyosins purified from the acellular slime mold physarum polycephalum by application of two different procedures (hatano and tazawa, 1968; kohama and kendrick-jones, 1986) were compared by sds-page and contraction experiments. in contrast to the 'hatano actomyosin', 'kohama actomyosin' contracts in a calcium sensitive manner, i.e., contraction occurs from zero calcium up to pca4, and is inhibited at greater than or equal to pca 3. distinct differences in sds gels are discussed. | 1987 | 3652215 |
| studies on microplasmodia of physarum polycephalum. vii. adhesion-dependent changes in the organization of the fibrillar actin system. | axenically-grown microplasmodia of the acellular slime mold physarum polycephalum were used to study adhesion-dependent changes in the spatial organization of the cytoplasmic microfilament system. results obtained by light- and electron microscopical techniques demonstrate the presence of a membrane-bound filament cortex in all microplasmodia, and the expression of additional cytoplasmic fibrils in specimens with tight contact to a substratum. the fibrils partly terminate in focal adhesion-sites ... | 1987 | 3652217 |
| [differences in the dna nucleotide sequences of the nuclear matrix of the myxomycete physarum polycephalum in the g2- and s-phases of the cell cycle]. | the extent of homology of the nuclear matrix dna isolated from the macroplasmodium of physarum polycephalum at g2- and s-phases of the cell cycle was studied using the molecular reassociation method. the results obtained point to the incomplete homology of dna samples prepared at g2- phases as compared to those obtained at s-phase. bearing this in mind it seems reasonable to suppose that the dna template may transfer through the nuclear matrix-attached replicative complex under the replication. | 1986 | 3775858 |
| flow cytometry of the differentiation of physarum polycephalum myxamoebae to cysts. | myxamoebae of physarum polycephalum, strain cld, were grown on agar lawns on live bacteria. myxamoebae were harvested, fixed and stained with propidium iodide. flow cytometry showed that, as in the case of physarum plasmodia, there is no g1 phase during rapid exponential growth. however, an apparent g1 phase was observed at the end of exponential growth when the culture arrested with the g1 dna content for about a day between growth and differentiation. most myxamoebae differentiated into cysts, ... | 1987 | 3780871 |
| in vivo levels of diadenosine tetraphosphate and adenosine tetraphospho-guanosine in physarum polycephalum during the cell cycle and oxidative stress. | cellular levels of diadenosine tetraphosphate (ap4a) and adenosine tetraphospho-guanosine (ap4g) were specifically measured during the cell cycle of physarum polycephalum by a high-pressure liquid chromatographic method. ap4a was also measured indirectly by a coupled phosphodiesterase-luciferase assay. no cell cycle-specific changes in either ap4a or ap4g were detected in experiments involving different methods of assay, different strains of p. polycephalum, or different methods of fixation of m ... | 1986 | 3785160 |
| effect of mycolase and amphotericin b on candida albicans and candida pseudotropicalis in vitro and in vivo. | a mixture of enzymes (mycolase) capable of lysing yeast cell walls was prepared from culture filtrates of physarum polycephalum. the enzymes present in mycolase included chitinase, beta-1,3-glucanases and exo-glycosidases. the ph optima of these enzymes were in the range 3.5-5.0 and they had low activities at ph 7.0. mycolase produced spheroplasts from candida pseudotropicalis and, unlike commercial enzyme preparations such as l1, chitinase, beta, 1,3-glucanase and beta-glucosidase, had some can ... | 1985 | 3895468 |
| expression of poriferasterol monoglucoside associated with differentiation of physarum polycephalum. | a glycolipid which was expressed during a differentiation from haploid myxoamoebae to diploid plasmodia of a true slime mold, physarum polycephalum, has been examined. in the amoeboid stage, cells did not contain this glycolipid, but after conjugation of the haploid cells, this substance appeared and increased in its amount. from structural studies of the purified glycolipid, it has been identified as poriferasterol monoglucoside. | 1987 | 3680272 |
| structure of the extrachromosomal ribosomal rna chromatin of physarum polycephalum. | isolated nucleoli from exponentially growing microplasmodia of physarum polycephalum were digested with micrococcal nuclease or dnaase i, or were photoreacted with trimethyl psoralen. in the coding region for the precursor of the ribosomal rna, micrococcal nuclease and dnaase i digestions show predominantly a smear, and treatment with psoralen leads to a fairly continuous crosslinking of the dna. all three assays are compatible with the absence of a typical nucleosomal array in most of the gene ... | 1987 | 3681980 |
| identification of the telomeric sequence of the acellular slime molds didymium iridis and physarum polycephalum. | we have determined the telomeric dna sequence of the acellular slime molds didymium iridis and physarum polycephalum. in both organisms the telomeres consist of tandem repeats of the hexamer 5'(ttaggg)3'. this sequence was determined by cloning and sequencing the telomeric fragment of the linear extrachromosomal ribosomal dna from didymium, as well as direct end labeling and sequencing the rdna from both organisms. interestingly, this sequence is identical to the telomeric dna sequence of the fl ... | 1987 | 3684591 |
| chemically induced changes in the morphology, dynamic activity and cytoskeletal organization of physarum cell fragments. | spherical cell fragments derived from physarum polycephalum by caffeine-treatment were used as an experimental system to investigate the influence of 15 externally applied substances on the general morphology, motile behavior and cytoskeletal organization of the acellular slime mold. in comparison to controls, the most obvious changes observed after chemical stimulation proved to be cytokinetic activities, ameboid-like movement phenomena, intense cell surface dynamics and formation of cytoplasmi ... | 1987 | 3690681 |
| the tubulin and histone genes of physarum polycephalum: models for cell cycle-regulated gene expression. | | 1986 | 3790134 |
| histone acetylation in replication and transcription: turnover at specific acetylation sites in histone h4 from physarum polycephalum. | histone h4 from growing cells is partially acetylated at lysines 5, 8, 12, and 16. the turnover rate at each of these sites was investigated by pulse-labeling plasmodia of physarum polycephalum with [3h]acetate for 55 min in either s phase or g2 phase of the cell cycle. labeled histone h4 was purified and digested with a protease which cleaves on the carboxyl side of arginine residues. the peptide containing the acetylation sites was purified by high-performance liquid chromatography. subfractio ... | 1986 | 3800393 |
| pulsed magnetic fields alter the cell surface. | pulsed magnetic fields (pmfs) are routinely used in the medical community to facilitate bone repair in clinical cases of non-union or pseudarthoses [(1984) orth. clin. no. am. 15, 61-87]. although this therapeutic regimen appears to be reasonably effective, the mechanism of action between specific pmfs and the target tissue remains unknown. adding urgency to the need to understand the mechanism are a wide number of reports that have appeared which demonstrate that pmfs similar to those in clinic ... | 1986 | 3699154 |
| transcription of alpha-tubulin and histone h4 genes begins at the same point in the physarum cell cycle. | in naturally synchronous plasmodia of physarum polycephalum, both tubulin and histone gene transcription define periodic cell cycle-regulated events. using a slot-blot hybridization assay and northern blot analysis, we have demonstrated that a major peak of accumulation of both alpha-tubulin and histone h4 transcripts occurs in late g2 phase. nuclear transcription assays indicate that both genes are transcriptionally activated at the same point in the cell cycle: mid g2 phase. while the rate of ... | 1986 | 3700471 |
| reactivation of cell-free models of endoplasmic drops from physarum polycephalum after glycerol extraction at low ionic strength. | the effect of calcium ions on the reactivation of cytoplasmic actomyosin contraction in cell-free models of endoplasmic drops from physarum polycephalum after glycerol extraction at low ionic strength depends on the duration of the extraction procedure: ca++ prevents contraction in 20-h extracted specimens, whereas after several days of extraction this ca++-sensitivity is lost. these results indicate an inhibitory effect of ca++ on cytoplasmic actomyosin contraction. | 1986 | 3709543 |
| reactivation of a cell-free model from physarum polycephalum: studies on cryosections indicate an inhibitory effect of ca++ on cytoplasmic actomyosin contraction. | cell-free models should offer "in situ conditions" to study the physiology of cytoplasmic actomyosin in its natural environment, while, if possible, still associated with its regulatory control proteins and other cytoplasmic components. detergents and glycerol as the usual media to permeabilize the plasmalemma and to extract a portion of the cytoplasmic components, are accompanied by several disadvantages. we investigated a cell-free model consisting of cryosections of plasmodial strands that we ... | 1986 | 3709544 |
| differences in the surface properties of the mating types of physarum polycephalum. | in the slime mold physarum polycephalum, formation of a diploid plasmodium occurs when compatible haploid amoebae fuse. to study cell surface changes associated with the fusion process, a non-destructive method known as aqueous, two-phase partitioning was employed. using a two-phase system of dextran and polyethylene glycol, we observed that the two mating types (rsd4 and ma185) have different partition coefficients and hence different surface properties. based on their partitioning behavior, ma ... | 1986 | 3709549 |
| biosynthesis and posttranslational acetylation of histones during spherulation of physarum polycephalum. | plasmodia of physarum polycephalum can be induced to differentiate into dormant spherules: dna-, rna- and protein-synthesis cease during this process. analysis of the histone h4 acetylation during spherulation revealed no significant changes of the relative acetate content and percentage of acetylated h4 subspecies. this result does not support a close correlation of histone acetylation and transcriptional activity. posttranslational incorporation of 3h-acetate into core histones decreased rapid ... | 1986 | 3714495 |
| molecular cloning of mrnas expressed specifically during spherulation of physarum polycephalum. | a cdna library was constructed using the poly(a)+ rna extracted from spherulating physarum polycephalum microplasmodia. this library (740 clones) was screened by differential hybridization with 32p-labeled poly(a)+ rna from growing plasmodia and developing spherules. the results showed that at least 30% of the clones corresponded to mrnas expressed specifically in spherulating plasmodia. the 35 spherulation-specific cdna clones giving the strongest hybridization signals were analysed. from this ... | 1986 | 3755618 |
| flow cytometry reveals a high degree of genomic size variation and mixoploidy in various strains of the acellular slime mold physarum polycephalum. | high-resolution flow cytometry, using avian erythrocytes as an internal standard, was employed to study constitutive genome size variation of g2-phase nuclei of physarum polycephalum strains during the macroplasmodial stage of their life cycle. our results document a previously unknown extent of genome size variation and mixoploidy in this organism. the unimodal diploid strain tu 291 displayed the largest genome of the strains tested; in contrast, the colonia strain displayed only half of the tu ... | 1986 | 3757696 |
| steady compensation of gravity effects in physarum polycephalum. | | 1986 | 3762714 |
| a morphogen for the sporulation of physarum polycephalum detected by cell fusion experiments. | the light stimulus, which under conditions of starvation induces the development of sporangia in the slime mold physarum polycephalum, can be transferred from the light-exposed part to the unexposed part of a plasmodium by means of plasma circulation. a small quantity of protoplasm from a sporulating donor plasmodium, which had passed through the premorphogenetic phase, was transferred by a short period fusion with a briefly starved, light-induction-incompetent acceptor plasmodium. this led to s ... | 1986 | 3770098 |
| an immunological approach to enrich a mitotic stimulator and to reveal g2-phase-specific proteins in physarum polycephalum. | purified antibodies from an antiserum against s-phase proteins of the myxomycete physarum polycephalum were attached to protein-a-sepharose cl-4b. a late g2-phase extract that contained a mitosis-stimulating protein was applied to this immunoadsorbent, and the mitosis-stimulating protein was enriched by a factor of ten. this protein, which is present in the cell in low amounts, is synthesized in late g2 phase and obviously degraded in a later stage of the cycle. immunoadsorption of a g2-phase ex ... | 1985 | 3889012 |
| the linear extrachromosomal dna of physarum polycephalum replicates and is maintained under non-selective conditions in two different lower eukaryotes. | the slime mould physarum polycephalum contains 100 to 200 molecules of extrachromosomal linear dna (pedna). two sets of the 19s and 26s ribosomal genes are located on each molecule of pedna. in the nonmitotic phase of the cell cycle pedna is localised in the nucleolus. the molecules are maintained throughout vegetative growth. in order to study the signals responsible for its maintenance, pedna was purified and introduced into the two distantly related yeasts saccharomyces cerevisiae and schizos ... | 1985 | 3889843 |
| fluctuations in s-adenosyl-l-methionine (adomet) during mitotic cycle of the myxomycete physarum polycephalum. | a sensitive radioisotope dilution method was used to measure the s-adenosyl-l-methionine (adomet) content in macroplasmodia of the slime mold physarum polycephalum during the mitotic cycle. the adomet pool had two maxima, one during mitosis, the other in the middle of g2 phase. | 1985 | 3896825 |
| [electron microscope study of changes in the chromatin structure in different functional states of nuclei of a ciliate bursaria truncatella and a myxomycete physarum polycephalum]. | chromatin structural organization was studied by means of electron microscopy in the macronuclei of ciliate bursaria truncatella at various stages of the life cycle (at different time intervals after cell division, in resting cysts and at excysting) and in the nuclei of myxomycete physarum polycephalum during the mitotic cycle. inactive chromatin was shown to be organized in compact clumps 100-300 nm in diameter linked with each other, their loop organization being convincingly demonstrated. upo ... | 1985 | 3920508 |
| phylogenetic relationships among eukaryotic kingdoms inferred from ribosomal rna sequences. | phylogenetic trees among eukaryotic kingdoms were inferred for large- and small-subunit rrnas by using a maximum-likelihood method developed by felsenstein. although felsenstein's method assumes equal evolutionary rates for transitions and transversions, this is apparently not the case for these data. therefore, only transversion-type substitutions were taken into account. the molecules used were large-subunit rrnas from xenopus laevis (animalia), rice (plantae), saccharomyces cerevisiae (fungi) ... | 1985 | 3932662 |
| identification of histone h1(0) in physarum polycephalum. its high level in the plasmodial stage increases in amount and phosphorylation in the sclerotial stage. | an antiserum specific for the globular domain of the bovine very lysine-rich histone subfraction h1(0) cross-reacted with a single protein band in the chromosomal proteins isolated from microplasmodia of the true slime mold physarum polycephalum. its amino acid composition was characteristic of a very lysine-rich histone which supported its identification as physarum h1(0). unlike physarum h1(0), which is 50% larger than mammalian h1, physarum h1(0) migrated very close to bovine h1(0) on sodium ... | 1986 | 3944138 |
| role of mrna 5'-terminal caps in translational dormancy of physarum polycephalum. | translational regulation of protein synthesis accompanies sclerotization in physarum polycephalum. plasmodial and sclerotial poly(a)+ rna were translated in a message-dependent wheat germ lysate in the presence of the cap analogue 7-methylguanosine-triphosphate to determine whether 5' structural alterations in mrna accompany translational repression. the translation of plasmodial and sclerotial poly(a)+ rna was reduced to identical levels suggesting that both rna populations are capped. the 5'-t ... | 1986 | 3947335 |
| actin-fragmin interactions as revealed by chemical cross-linking. | a one to one complex of actin and fragmin (a capping protein from physarum polycephalum plasmodia) was cross-linked with 1-ethyl-3-[3-(dimethylamino)propyl] carbodiimide. the cross-linking reaction generated two cross-linked products with slightly different molecular weights (88 000 and 90 000) as major species. they were cross-linked products of one actin and one fragmin. the cross-linking site of fragmin in the actin sequence was determined by peptide mappings [sutoh, k. (1982) biochemistry 21 ... | 1986 | 3955005 |