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Proceedings of the National Academy of... Dec 1973A procedure for screening several thousand clones for alterations in a specific gene product was apapplied to mutagenized cultures of Dictyostelium discoideum. Six...
A procedure for screening several thousand clones for alterations in a specific gene product was apapplied to mutagenized cultures of Dictyostelium discoideum. Six strains were recovered which had less N-acetylglucosaminidase (EC 3.2.1.30) than the wild type. In addition, we isolated four strains in which the enzyme was temperature-sensitive. The enzyme from one of these strains had an altered substrate affinity.N-Acetylglucosaminidase is present at a low level in cells grown on bacteria and increases up to 10-fold during the aggregation stage of development. The enzyme appears to be essential to maintain migrating pseudoplasmodia of normal size, as shown by the fact that all of the mutant strains which accumulate very little N-acetyl-glucosaminidase formed only small migrating pseudoplasmodia containing less than 10% the number of cells found in the wild-type pseudoplasmodia. The small pseudoplasmodia migrated at less than a third the rate of wild-type pseudoplasmodia and ultimately formed diminutive fruiting bodies. N-Acetylglucosaminidase thus appears to be a developmental enzyme that functions during the migration stage.
Topics: Acetamides; Clone Cells; Genes; Hexosaminidases; Lysosomes; Mutation; Myxomycetes; Temperature
PubMed: 4519628
DOI: 10.1073/pnas.70.12.3356 -
Proceedings of the National Academy of... Sep 1967
Topics: Adenine Nucleotides; Chemotaxis; Escherichia coli; Myxomycetes; Spectrophotometry
PubMed: 4861307
DOI: 10.1073/pnas.58.3.1152 -
The FEBS Journal Jun 2006Trans-splicing group I ribozymes have been introduced in order to mediate RNA reprogramming (including RNA repair) of therapeutically relevant RNA transcripts. Efficient...
Trans-splicing group I ribozymes have been introduced in order to mediate RNA reprogramming (including RNA repair) of therapeutically relevant RNA transcripts. Efficient RNA reprogramming depends on the appropriate efficiency of the reaction, and several attempts, including optimization of target recognition and ribozyme catalysis, have been performed. In most studies, the Tetrahymena group IC1 ribozyme has been applied. Here we investigate the potential of group IC1 and group IE intron ribozymes, derived from the myxomycetes Didymium and Fuligo, in addition to the Tetrahymena ribozyme, for RNA reprogramming of a mutated alpha-mannosidase mRNA sequence. Randomized internal guide sequences were introduced for all four ribozymes and used to select accessible sites within isolated mutant alpha-mannosidase mRNA from mammalian COS-7 cells. Two accessible sites common to all the group I ribozymes were identified and further investigated in RNA reprogramming by trans-splicing analyses. All the myxomycete ribozymes performed the trans-splicing reaction with high fidelity, resulting in the conversion of mutated alpha-mannosidase RNA into wild-type sequence. RNA protection analysis revealed that the myxomycete ribozymes perform trans-splicing at approximately similar efficiencies as the Tetrahymena ribozyme. Interestingly, the relative efficiency among the ribozymes tested correlates with structural features of the P4-P6-folding domain, consistent with the fact that efficient folding is essential for group I intron trans-splicing.
Topics: Animals; Base Sequence; Binding Sites; COS Cells; Chlorocebus aethiops; In Vitro Techniques; Introns; Molecular Sequence Data; Myxomycetes; Nucleic Acid Conformation; RNA Splicing; RNA, Catalytic; RNA, Messenger; Tetrahymena; Trans-Splicing; alpha-Mannosidase
PubMed: 16817905
DOI: 10.1111/j.1742-4658.2006.05295.x -
Journal of Bacteriology Nov 1969A method has been developed for inducing spherule formation (spherulation) in the myxomycete Physarum polycephalum by transferring the culture to synthetic medium...
A method has been developed for inducing spherule formation (spherulation) in the myxomycete Physarum polycephalum by transferring the culture to synthetic medium containing 0.5 m mannitol or other polyols. This morphogenetic process occurred within 12 to 35 hr after the inducer was added. The mature spherules existed as distinct morphogenetic units, in contrast to the clusters of spherules formed during starvation. Ninety per cent of the spherules germinated by 24 hr in synthetic medium. The changes in the synthesis of ribonucleic acid (RNA), deoxyribonucleic acid (DNA), and protein during plasmodial growth, spherulation, and germination of spherules are described. When spherule formation was completed, RNA, protein, and DNA decreased, compared with the values at the beginning of the conversion. The incorporation of (3)H-uridine into trichloroacetic acid-insoluble material was different in each of these periods, and this incorporation was sensitive to actinomycin D. The amount of glycogen increased during growth, whereas it decreased during spherulation. (14)C-glucose could be taken up by the cells in the presence of the inducer, and mannitol could not replace glucose as a source of energy. The mode of action of mannitol and its mechanism of induction are discussed.
Topics: Alcohols; Carbohydrates; Carbon Isotopes; Culture Media; DNA; Dactinomycin; Glucose; Glycogen; Mannitol; Myxomycetes; Protein Biosynthesis; RNA; Tritium; Uridine
PubMed: 5389734
DOI: 10.1128/jb.100.2.673-678.1969 -
Yakugaku Zasshi : Journal of the... Sep 2007The Myxomycetes (true slime molds) are an unusual group of primitive organisms that may be assigned to one of the lowest classes of eukaryotes. As their fruit bodies are... (Review)
Review
The Myxomycetes (true slime molds) are an unusual group of primitive organisms that may be assigned to one of the lowest classes of eukaryotes. As their fruit bodies are very small and it is very difficult to collect much quantity, few studies have been made on the chemistry of myxomycetes. We studied spore germination experiments of hundreds of field-collected myxomycetes collected in Japan, and succeeded in laboratory culture of plasmodia of several myxomycetes in a practical scale for natural products chemistry studies. Pyrroloiminoquinones, polyene yellow pigments, and a peptide lactone were isolated from cultured plasmodia of myxomycetes, while new naphthoquinone pigments, cycloanthranilylprolines, tyrosine-kinase inhibitory bisindoles, a cytotoxic triterpenoid aldehyde lactone, a dibenzofuran glycoside, and sterols possessing an unprecedented 2,6-dioxabicyclo[2.2.2] octan-3-one ring system, were also isolated from field-collected fruit bodies of myxomycetes.
Topics: Animals; Benzofurans; Drug Design; Glycosides; Lactones; Myxomycetes; Naphthoquinones; Polyenes; Proline; Pyrroloiminoquinones; Sterols
PubMed: 17827919
DOI: 10.1248/yakushi.127.1369 -
PLoS Computational Biology Dec 2014How social groups and organisms decide between alternative feeding sites or shelters has been extensively studied both experimentally and theoretically. One key result...
How social groups and organisms decide between alternative feeding sites or shelters has been extensively studied both experimentally and theoretically. One key result is the existence of a symmetry-breaking bifurcation at a critical system size, where there is a switch from evenly distributed exploitation of all options to a focussed exploitation of just one. Here we present a decision-making model in which symmetry-breaking is followed by a symmetry restoring bifurcation, whereby very large systems return to an even distribution of exploitation amongst options. The model assumes local positive feedback, coupled with a negative feedback regulating the flow toward the feeding sites. We show that the model is consistent with three different strains of the slime mold Physarum polycephalum, choosing between two feeding sites. We argue that this combination of feedbacks could allow collective foraging organisms to react flexibly in a dynamic environment.
Topics: Decision Making; Feedback, Physiological; Models, Biological; Physarum polycephalum
PubMed: 25521109
DOI: 10.1371/journal.pcbi.1003960 -
The Journal of Cell Biology Feb 1975Myxamebas of Polysphondylium violaceum were grown in liquid medium and processed for electron microscopy. Mitosis is characterized by a persistent nuclear envelope,...
Myxamebas of Polysphondylium violaceum were grown in liquid medium and processed for electron microscopy. Mitosis is characterized by a persistent nuclear envelope, ring-shaped extranuclear spindle pole bodies (SPBs), a central spindle spatially separated from the chromosomal microtubules, well-differentiated kinetochores, and dispersion of the nucleoli. SPBs originate from the division, during prophase, of an electron-opaque body associated with the interphase nucleus. The nuclear nevelope becomes fenestrated in their vicinity, allowing the build-up of the intranuclear, central spindle and chromosomal microtubules as the SPBs migrate to opposite poles. At metaphase the chromosomes are in amphitelic orientation, each sister chromatid being directly connected to the corresponding SPB by a single microtubule. During ana- and telophase the central spindle elongates, the daughter chromosomes approach the SPBs, and the nucleus constricts in the equatorial region. The cytoplasm cleaves by furrowing in late telophase, which is in other respects characterized by a re-establishment of the interphase condition. Spindle elongation and poleward movement of chromosomes are discussed in relation to hypotheses of the mechanism of mitosis.
Topics: Cell Nucleus; Chromosomes; Cytoplasm; Escherichia coli; Microscopy, Electron; Microtubules; Mitosis; Models, Biological; Myxomycetes; Organoids
PubMed: 1090631
DOI: 10.1083/jcb.64.2.480 -
PloS One 2013Myxomycetes, or plasmodial slime-moulds, are one of the largest groups in phylum Amoebozoa. Nonetheless, only ∼10% are in the database for the small subunit (SSU)...
Myxomycetes, or plasmodial slime-moulds, are one of the largest groups in phylum Amoebozoa. Nonetheless, only ∼10% are in the database for the small subunit (SSU) ribosomal RNA gene, the most widely used gene for phylogenetics and barcoding. Most sequences belong to dark-spored Myxomycetes (order Fuscisporida); the 318 species of superorder Lucisporidia (bright-spored) are represented by only eleven genuine sequences. To compensate for this, we provide 66 new sequences, 37 SSU rRNA and 29 elongation factor 1-alpha (EF-1α), for 82% of the genera of Lucisporidia. Phylogenetic analyses of single- and two-gene alignments produce congruent topologies and reveal both morphological characters that have been overemphasised and those that have been overlooked in past classifications. Both classical orders, Liceida and Trichiida, and several families and genera are para/polyphyletic; some previously unrecognised clades emerge. We discuss possible evolutionary pathways. Our study fills a gap in the phylogeny of Amoebozoa and provides an extensive SSU rRNA sequence reference database for environmental sampling and barcoding. We report a new group I intron insertion site for Myxomycetes in one Licea.
Topics: Evolution, Molecular; Genes, Protozoan; Introns; Myxomycetes; Peptide Elongation Factor 1; Phylogeny; RNA, Ribosomal; Spliceosomes; Spores, Protozoan
PubMed: 23667494
DOI: 10.1371/journal.pone.0062586 -
Journal of Bacteriology Aug 1970The size distribution and synthesis of polypeptide chains and the polysome patterns were studied during sporulation of the slime mold Physarum polycephalum, and were...
The size distribution and synthesis of polypeptide chains and the polysome patterns were studied during sporulation of the slime mold Physarum polycephalum, and were compared with nonsporulating controls. The proteins were divided into a 27,000 x g supernatant (buffer-soluble proteins) and a pellet (buffer-insoluble proteins) while still native. The sodium dodecyl sulfate complexes of the denatured proteins were separated on polyacrylamide gels containing urea. The following differences were found between sporulating and nonsporulating cultures. (i) The distribution of the soluble proteins into bands from sporulating and control cultures was the same in stained patterns; however, there was a slight shift toward increased synthesis of larger polypeptide chains in the radioactivity patterns of the soluble proteins in sporulating cultures. (ii) The amount of histones in the sporulating cultures was less than 30% of the values in the controls. Also, histone synthesis was reduced to less than 10% of that in the nonsporulating controls. In addition, proteins in three defined regions, corresponding to molecular weights of 70,000 to 75,000 (I), 55,000 (II), and 41,000 (III), were synthesized in sporulating cultures at a rate at least twice that in controls. Polypeptides corresponding to peaks I and II could be extracted from purified walls of mature spores. (iii) The polysome pattern as revealed by sucrose density centrifugation showed a breakdown of heavy polysomes at 3 hr after illumination, with their reappearance 4 hr later. The latter pattern, however, differed from that of the nonsporulating control in that the amount of light polysomes was reduced. This might account for the reduction in histone synthesis.
Topics: Cell Wall; Electrophoresis, Disc; Histones; Leucine; Molecular Weight; Myxomycetes; Peptide Biosynthesis; Spores; Tritium
PubMed: 5464525
DOI: 10.1128/jb.103.2.356-363.1970 -
The Journal of Cell Biology May 1965Myxomycete plasmodia of four different types (not including Physarum polycephalum) were studied in thin sections viewed in the electron microscope. In the cytoplasm of...
Myxomycete plasmodia of four different types (not including Physarum polycephalum) were studied in thin sections viewed in the electron microscope. In the cytoplasm of the protoplasmodia of Clastoderma debaryanum and the phaneroplasmodia of Fuligo septica fixed in situ, fibrillar differentiations of three rather distinct kinds were observed. One of these is filamentous and closely resembles the filaments (or "microtubules") of the mitotic apparatus of other species. The larger phaneroplasmodia of two species belonging to the Physarales and the plasmodium of Hemitrichia vesparium showed fewer and less well defined fibrils, and no fibrils were seen in the aphanoplasmodium of Stemonitis fusca. Good stabilization of such fibrils in larger plasmodia may require fixation methods more rigidly controlled than those which succeed with microscopic protoplasmodia. The function of the observed fibrils cannot yet be determined. Their presence in cytoplasm fixed in situ, however, lends support to those theories of protoplasmic movement which are dependent on integral cross-bonding of one or a few molecular species.
Topics: Cell Differentiation; Cytoplasm; Cytoskeleton; Electrons; Microscopy; Microscopy, Electron; Microtubules; Myxomycetes; Plasmodium; Research
PubMed: 14287182
DOI: 10.1083/jcb.25.2.305