- Volume 125, Issue 2, 1981
Volume 125, Issue 2, 1981
- Biochemistry
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Isolation and Characterization of the DNA-dependent RNA Polymerase of Rhizobium leguminosarum 300
More LessThe DNA-dependent RNA polymerase isolated from Rhizobium leguminosarum 300 contains the following subunits: β′, β, polypeptide A and α (molecular weights 149000, 146000, 93000 and 42000, respectively). Polypeptide A is postulated to be the σ factor of the enzyme. The experimental conditions used for the in vitro assay of the enzyme activity, with plasmid pMB9 as template, included: 40 mm-Tris/HCl (pH 7.9), 150mm-NaCl, 5 mm MgCl2, at 34 °C. The isolated enzyme was shown by electron microscopy to bind specifically to the region of early promoters of DNA of the Escherichia coli bacteriophage T7. Therefore, Rhizobium-specific promoters may have base sequences in common with those of E. coli.
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Calcium Ions, Oxygen and Acetylene Reduction (Nitrogen Fixation) in the Unicellular Cyanobacterium Gloeocapsa sp. 1430/3
More LessCultures of Gloeocapsa sp. 1430/3 rapidly and irreversibly lost their ability to reduce acetylene when incubated with 1 mm-EDTA, either in the light or aerobically in the dark. However, EDTA did not inhibit acetylene reduction by cultures of Gloeocapsa incubated anaerobically in the dark. It is suggested that EDTA depletes the cyanobacterial cells of Ca2+ and thereby destroys a Ca2+-dependent process by which nitrogenase is protected from inactivation by oxygen.
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The Involvement of Nitric Oxide in the Inhibition of the Phosphoroclastic System in Clostridium sporogenes by Sodium Nitrite
More LessThe phosphoroclastic system was demonstrated in cell-free extracts of Clostridium sporogenes by the production of carbon dioxide, acetyl phosphate, ATP and reduced NAD in the presence of pyruvate. The kinetics of acetyl phosphate production and NAD reduction were investigated. The addition of sodium nitrite to a suspension of C. sporogenes in glucose medium resulted in a rapid decrease in intracellular ATP concentration which was accompanied by an accumulation of pyruvate in the medium. This accumulation of pyruvate was caused by inhibition of the phosphoroclastic system by nitrite. Nitrite inhibits this system by reaction of nitric oxide, formed from nitrite, with the non-haem iron of pyruvate: ferredoxin oxidoreductase.
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Effects of Nucleotides and Sugar Nucleotides on Mannosyltransferase Activity in Saccharomyces cerevisiae
More LessA survey was made of the effects of different nucleotides, sugar nucleotides and sugars on mannosyltransferase activity in Saccharomyces cerevisiae to assess their possible role in the regulation of mannan synthesis. Mannosyltransferase activity in spheroplast lysate and washed membrane preparations was not markedly affected by sugars, nucleoside monophosphates or by most of the sugar nucleotides tested. GDP and GTP both inhibited enzyme activity. ATP caused a significant stimulation, and analysis of the mannan formed suggested that this was due mainly to increased synthesis of the polysaccharide moiety. GDPglucose was a competitive inhibitor of total mannan synthesis and also inhibited the formation of mannolipids.
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Genetic and Biochemical Aspects of Yeast Sterol Regulation Involving 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase
More LessDeterminations of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) activity in haploid strains and diploid hybrids of wild-type Saccharomyces cerevisiae revealed that a genetic basis exists for control of this key regulatory enzyme in which low enzyme activity is phenotypically dominant to high enzyme activity. These observations suggested the existence of an inhibitor of reductase activity or a suppressor of enzyme synthesis. Feeding studies using an early sterol intermediate (mevalonolactone) and end-product sterol (ergosterol) indicated that a secondary regulatory site in this pathway operates to decrease the activity of HMG-CoA reductase. This diminution of activity was paralleled by increases in the accumulation of squalene, suggesting that this intermediate (or another isoprenoid derivative) may also play a significant role in the in vivo regulation of sterol biosynthesis. Lastly, feedback inhibition of HMG-CoA reductase by ergosterol was demonstrated in a yeast mutant which is permeable to this sterol. These studies showed that yeast can serve as a eukaryotic model system for a combined biochemical and genetic investigation into the factors which control the activity of HMG-CoA reductase.
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The Light-reversible Binding of Carbon Monoxide to Cytochrome a 1 in Escherichia coli K12
More LessDifference spectra at 77 K of intact Escherichia coli K12 grown under oxygen-limited conditions revealed the presence of cytochrome a 1. In the presence of CO, the band of the reduced form, observed in both the α and λ regions of the spectrum, was decreased. Dualwavelength scanning spectrophotometry at sub-zero temperatures revealed a flash-dissociable CO-binding pigment with a broad band around 595 nm, identified as cytochrome a 1 Photolysis in the presence of O2 revealed no such band in difference spectra where the reference spectrum was that of the CO-liganded form, a result consistent with the binding of O2 to cytochrome a 1. Repeated cycles of photolysis and recombination of the cytochrome with CO were demonstrated at −46 °C. The apparent energy of activation for the reaction with CO was 10·9 kcal mol−1 (45·6 kJ mol−1). The results are discussed in relation to previous assumptions and results regarding ligand binding to cytochrome a 1 and the function of this cytochrome in bacterial respiration.
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The Effect of Salts on Enzymes of the Respiratory Chain of Marine Bacterium Strain 1055-1
More LessThe effect of salts on components of the respiratory chain of marine bacterium 1055–1 has been studied. Sodium ions activated the NADH oxidase system. This was not due to activation of NADH dehydrogenase but resulted from the activation of some other components that were membrane-bound. One of these activated components was involved in the 2-heptyl-4-hydroxyquinoline N-oxide (HOQNO)-sensitive reduction of ubiquinone. In contrast, succinate oxidase was inhibited by high concentrations of salts and it was concluded that the inhibited component was succinate dehydrogenase.
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- Development And Structure
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Ultrastructural Studies of the Free Zoospore of the Rumen Phycomycete Neocallimastix frontalis
More LessThe structure of the free zoospores of Neocallimastix frontalis has been examined by electron microscopy of thin-sectioned and negatively stained preparations. There are up to 15 flagella arranged in two rows. The free end of each flagellum is narrow and its tip does not contain microtubules. The flagella and the cell body are coated with distinct surface layers composed of regular arrays of particles and fibrils, respectively. The cell body contains a variety of inclusions. Near to the flagellar pole there are numerous membrane-bound electron-dense globules about 0·2 to 0·7 μm in diameter, between which are microtubules, particles and small vesicles. In the region of the centrally placed nucleus are arrays of helices of ribosome-like particles. These particles also occur in the form of globular aggregates, each partially enclosed within a membrane. The remainder of the cytoplasm is filled with material resembling glycogen. The zoospores stain positively for glycogen and contain ribonucleasesensitive particulate material which is stained by toluidine blue.
Scanning electron microscopy shows that the zoospores attach to the substrate by the flagellar pole.
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Deficiency of Autolytic Activity in Bacillus subtilis and Streptococcus pneumoniae is Associated with a Decreased Permeability of the Wall
More LessAutolytic-deficient mutants of Bacillus subtilis which grow as chains of non-separated bacilli have been isolated by a procedure involving filtration of mutagenized cultures through glass-sinter filters. The mutants obtained were some 80–90% deficient in both autolysins, N-acetylmuramoyl-l-alanine amidase and endo-β-N-acetylglucosaminidase. Treatment of one of these mutants with 5 m-LiCl extracted only about 20% of the protein obtained from an equivalent amount of the autolysin-containing bacilli. Similarly, a reduction of 40–60% in LiCl-extractable protein was obtained with autolytic-deficient Streptococcus pneumoniae whether these organisms lacked the autolytic enzyme or were phenotypically deficient by growth in ethanolamine-containing medium. Chromatography on Sephadex G-100 of the protein extracted from B. subtilis and S. pneumoniae revealed that the major difference between autolytic-deficient and parent organisms was a decrease in proteins of high molecular weight. Smaller differences were observed in a second fraction which contained low molecular weight material and proteins such as the autolysins, whose elution from the column was retarded by interaction with the Sephadex. Further examination of the fractionated protein from B. subtilis by sodium dodecyl sulphate-polyacrylamide gel electrophoresis confirmed that the major difference between the extracts was in the amount of protein present and did not result from marked changes in the size of the extracted proteins. These observations suggest that autolysin deficiency in B. subtilis and S. pneumoniae results in a change in the porosity (permeability) of the bacterial wall.
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- Ecology
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Acanthamoeba castellanii, a Predator of Cyanobacteria
More LessAcanthamoeba castellanii was isolated from soil and water as a predator of cyanobacteria. Several strains of A. castellanii consumed cyanobacteria but there were differences in predatory activity between strains. The unicellular Gloeocapsa alpicola and filamentous Anabaena flos-aquae were particularly susceptible to predation. Under optimal conditions the amoebae fed voraciously but they encysted when the cyanobacterial food supply was exhausted. Predation was initiated by engulfment of whole cyanobacteria and, in the case of Anabaena flos-aquae, severance of filaments. This was followed by digestion in vacuoles.
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- Genetics And Molecular Biology
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Initiation of Aggregation by Dictyostelium discoideum in Mutant Populations Lacking Pulsatile Signalling
More LessThe proportion of a wild-type population capable of initiating aggregation centres in starving fields of Dictyostelium discoideum was investigated using mixed populations of a few wild-type amoebae and a large excess of a mutant incapable of initiating aggregation signals but fully capable of responding to them. For this purpose an aggregation-deficient mutant (designated NP160) was isolated that showed high sensitivity to wild-type strains in synergy tests. This mutant formed normal cell-surface cyclic AMP receptors and phosphodiesterases and was fully capable of chemotaxis to cyclic AMP. Although it had an active adenylate cyclase and formed cyclic AMP, it was deficient in the pulsatile regulation of this enzyme and did not initiate or relay pulsatile cyclic AMP signals and did not form cell adhesive contact sites A unless given artificial cyclic AMP pulses. When synergistic mixtures of this mutant and the wild-type were made, the mutant formed fruiting bodies at frequencies indicating that up to 1 in 5 of the wild-type cells could initiate aggregation centres when present at a ratio of between 1 in 500 and 1 in 10000 of the mixed amoebal population.
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Transfer, Maintenance and Expression of P Plasmids in Strains of Cowpea Rhizobia
More LessSeven slow-growing strains of cowpea rhizobia (Rhizobium sp.) were tested for ability to receive the P plasmids pRD1 and R68.45 from Escherichia coli. The frequency of transfer was 2 × 10−4 −2 × 10−6 for five strains including CB756, but no transfer was detected for the other two. The his-nif segment of pRD1 was lost at high frequency in CB756 transconjugants whilst pRD1 and R68.45 tra and antibiotic resistance genes were stable through 50–100 generations in non-selective media even though growth rates of CB756 were almost halved in transconjugant clones. Furthermore, plasmids were maintained in three strains tested during passage through root nodules, although there were some differences in symbiotic expression between transconjugants and their wild-type parents. A colour change was effected by CB756 in the presence of 6-cyanopurine and therefore could possibly be used as an indicator of nif expression in addition to acetylene reduction in culture.
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Linkage Map and Properties of a Bacillus subtilis Strain Carrying a Non-tandem Duplication of the purB-tre Region of the Chromosome
More LessTransfer of the ‘trpE26 mutation’ of Bacillus subtilis into 168-type strains does not always lead to simultaneous induction of both chromosomal aberrations (translocation and inversion) of the strains carrying it. A strain was isolated (GSY1835) which possessed new rearrangements. It has some characteristics of the donor parent-a mutation in the trpE locus (trpE30) which does not revert, a similar effect on tryptophan biosynthesis and loss of linkage between the markers flanking the trp operon. Unlike the ‘trpE26 strains’, GSY1835 yielded haploid Trp+ transformants and transductants. Merodiploid Trp+ clones were also produced, but in a fairly low proportion (about 10%). The genetic structure of GSY1835 was found to differ considerably from that of a ‘trpE26 strain’. The strain carries a non-tandem duplication of part of segment I of the chromosome (segment Ib: purB-tre), with the two copies in inverted position. This duplication is very stable. Recombination may occur betweeen the two copies. The results fit two configurations for the genetic map of the strain and its derivatives. Map 1 differs from that of strain 168 by the insertion of the second copy of Ib inside the trpE locus. In map 2, introduction of this second copy at the same site is accompanied by an inversion of the lower part of the chromosome (segments C-D-II). The haploid Trp+ clones have the genetic map of strain 168. Models are proposed to interpret the formation of strain GSY1835 (trpE30) and the production of the haploid Trp+ transformants and transductants.
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Ascospore Mutants and Genetic Map of Ascobolus immersus Stock 28
More LessThree hundred and seventy mutants of the ascomycete Ascobolus immersus stock 28 were isolated. They were assigned to at least 75 loci. Mutations in 33 loci affect ascospore morphology: 19 of these loci affect pigmentation, 5 affect pigment distribution and 9 affect shape. The reliability of various phenotypes and the role of multigenic control on ascospore morphogenesis are discussed. Other mutations affect the mycelial growth rate or morphology and sporulation. A total of 56 loci have been mapped in 13 linkage groups corresponding to at least nine chromosomes. Using an intermediary strain, successful crosses between two intersterile stocks of Ascobolus (28 and 50) demonstrated that 12 pairs of mutants isolated in each stock correspond to 12 homologous loci.
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- Medical Microbiology
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Attachment of Chlamydia psittaci to Formaldehyde-fixed and Unfixed L Cells
More LessThe attachment of Chlamydia psittaci, strain 6BC, to formaldehyde-fixed and unfixed L cells was studied. Cations were found to be required for attachment to both fixed and unfixed cells. The requirement for cations was largely eliminated when the net negative surface charge on fixed cells was reduced. A high concentration of sodium chloride (0·5 m) prevented binding and removed chlamydiae which were attached to fixed and unfixed cells, whereas non-ionic detergents had no effect on attachment of C. psittaci to fixed cells. The effect of various modifications of C. psittaci and L cell surfaces on attachment was also determined. Of the treatments tested, only trypsinization and periodate oxidation of L cells and acetic anhydride, heat and periodate treatments of C. psittaci reduced binding. Various lectins and high concentrations of neutral sugars had no effect on attachment, whereas amino sugars and several organic amines inhibited attachment. These results suggest that the initial phase of attachment requires electrostatic interactions between host and parasite surfaces, and that amino and carbohydrate groups on the surface of C. psittaci and glycoproteins on the surface of L cells may be directly or indirectly required for attachment.
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Porin from the Outer Membrane of Escherichia coli: Immunological Characterization of Native and Heat-dissociated Forms
More LessAntisera against porin oligomers isolated from the outer membrane of Escherichia coli O26 K60 and against porin monomers from the same bacterial strain were elicited in rabbits by intramuscular administration with Freund’s complete adjuvant. Antibodies against native porin oligomers reacted strongly with porin oligomers, as revealed by sodium dodecyl sulphate-polyacrylamide gel immunoperoxidase (SGIP) analysis, the enzyme-linked immunosorbent assay (ELISA) and immunodiffusion, but showed no significant reaction with denatured monomers. The antibodies were completely absorbed by the intact outer membrane-peptidoglycan complex, which suggests that they were directed against antigenic determinants expressed on the outside of the intact outer membrane. Antibodies directed against denatured porin monomers reacted strongly with monomers in all tests but reacted only very weakly with porin oligomers. They were not absorbed by the native porin situated in the intact outer membrane. This indicates that the major antigenic determinants of the denatured porin monomer are hardly related to those of the native trimer situated in the intact outer membrane. The antigenic determinants of the denatured monomer seem to become fully expressed only after dissociation and denaturation of the porin. It is concluded that the immunological relationship of denatured porin monomers derived from many strains of E. coli and other Enterobacteriaceae which was reported in previous studies may not indicate that native porin trimers of these strains are also related.
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- Physiology And Growth
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Utilization of Aliphatic Amides and Formation of Two Different Amidases by Alcaligenes eutrophus
More LessThe utilization of aliphatic amides and their metabolism in the facultatively chemolithotrophic hydrogen bacterium Alcaligenes eutrophus has been investigated. This strain grew on fructose with formamide or acetamide as nitrogen sources, and these substrates induced formamidase. Ammonia repressed formamidase formation. Propionamide, butyramide and valeramide served as carbon and nitrogen sources and induced a different amidase, valeramidase. This enzyme was highly active with valeramide and less active with shorter acylamides but did not hydrolyse formamide. Valeramidase was subject to catabolite repression by fructose and succinate. Mutants altered in the regulation of amidase formation were isolated. A mutant able to grow with formamide and acetamide as carbon source formed formamidase constitutively, and this enzyme could not be repressed by ammonia in this mutant; its growth on formamide was autotrophic. A mutant able to grow with acetamide but not with formamide as carbon source was semi-constitutive for valeramidase; in this mutant the inducer specificity was altered and acetamide was the most potent inducer of valeramidase.
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Effect of Growth Rate and Nutrient Limitation on the Adenine Nucleotide Content, Energy Charge and Enzymes of Adenylate Metabolism in Azotobacter beijerinckii
More LessThe effects of dilution rate and glucose, nitrogen or oxygen limitation on the intracellular and extracellular concentrations of adenine nucleotides, on the adenylate energy charge and on the specific activities of four enzymes of adenylate metabolism, have been investigated with chemostat cultures of Azotobacter beijerinckii. Under glucose limitation both ATP and ADP contents and the total adenylate pool increased with an increase in dilution rate while the energy charge remained constant at 0·85; the concentrations of extracellular ADP and AMP rose. With nitrogen limitation all the intracellular adenylates decreased with an increase in dilution rate while the concentration of extracellular ADP and AMP decreased markedly; the energy charge rose from 0·72 to 0·79. Under oxygen limitation the ATP content and total adenylate pool increased at higher dilution rates and the energy charge increased from 0·71 at D = 0·1 h−1 to 0·81 at D = 0·15 h−1 and then remained fairly constant; the concentration of extracellular adenylates decreased.
The specific activity of adenylate kinase was relatively unaffected by dilution rate under nitrogen or oxygen limitation but was inversely related to it in organisms grown under glucose limitation. AMP nucleosidase activity was inversely related to dilution rate under glucose-, nitrogen- and oxygen-limited conditions, while adenosine deaminase was relatively unaffected by dilution rate except for a decrease in organisms from oxygen-limited cultures at lower growth rates. The specific activity of adenine deaminase was inversely related to dilution rate in organisms grown under glucose and nitrogen limitation but showed little change under oxygen limitation. The principal route of AMP degradation in A. beijerinckii is mediated by AMP nucleosidase and adenine deaminase.
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The Number of Hydrogenases in Cyanobacteria
G. Eisbrenner, P. Roos and H. BotheCyanobacteria consume H2 by two different pathways: the oxyhydrogen reaction and anaerobic, light-dependent H2 utilization. The two pathways are shown here to be induced differently by incubating cyanobacteria anaerobically under H2.Inthe unicellular Anacystis nidulans and in N2 − and NH+ 4-grown Anabaena cylindrica and Nostoc muscorum,such treatment greatly enhances the activity of the oxyhydrogen reaction in all cell types. In contrast, the light-dependent pathway, determined by the H2-dependent photoreduction of NADP+, is demonstrable with higher activity only in heterocysts.
Whereas the activity of the oxyhydrogen reaction isdirectly correlated to the structural integrity of membranes, there is an inverse correlation between membrane integrity and H2 formation catalysed by hydrogenase. These findings, together withphysiological considerations, suggest that a ‘reversible’ soluble hydrogenase does not exist in photoautotrophic cyanobacteria. No definite conclusions about the existence of two membrane-bound uptake hydrogenases are possible at present.
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Adaptation of Glucose-grown Saccharomyces cerevisiae to Gluconeogenic Growth and Sporulation
More LessWhen cells of Saccharomyces cerevisiae growing exponentially on d-glucose as sole carbon source were washed and transferred to buffered yeast nitrogen base containing 100 mm-acetate, they were unable to resume growth for several days whereas they adapted within a few hours to grow (slowly) on ethanol, and within 12 h to grow on pyruvate. After the cell transfer, oxygen consumption and ATP concentration decreased rapidly but recovered within a few hours on ethanol, more slowly on pyruvate, and only after 70 h on acetate. When the acetate culture had lost all detectable ATP, the viable cell titre slowly decreased until after 70 h enough cells had adapted to resume growth. At lower acetate concentrations (optimally 5 to 15 mm), ATP decreased less, and growth resumed within 1 d. After transfer from glucose medium to buffer plus a carbon source, cells sporulated equally well at ethanol concentrations from 20 to 150 mm and at pH 5·5 or 7·0; with dihydroxyacetone, another uncharged carbon source, sporulation was optimal at concentrations between 30 and 50 mm and about equal at pH 5·5 and 7·0. In contrast, after transfer from glucose medium to buffer plus acetate, cells sporulated at pH 5·5 optimally with 15 mm-acetate but not with 50 mm-acetate or more; at pH 7·0 sporulation showed a broader optimum of acetate concentration around 50 mm. The results indicated that in cells not adapted to gluconeogenesis, high concentrations of neutral acetic acid molecules caused complete consumption of intracellular ATP; consequently the cells could not adapt to gluconeogenesis for a long time.
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Changes in Metabolic Activity of Proteus mirabilis during Swarming
More LessProteus mirabilis in the long, swarming form had altered metabolic activity compared with bacteria in non-swarming phases on solid media. During swarming the rates of incorporation of precursors into DNA, RNA and protein, as measured in broth cultures immediately after harvesting from swarm plates, were lowered. The rates of uptake of these precursors into the bacteria were also lowered, and at the same time the rate of oxygen uptake was reduced to less than 20 % of the normal rate, although intracellular ATP concentrations remained constant. The return of macromolecular synthesis and oxygen uptake to preswarming rates corresponded to the end of the active swarm period. The results indicate that in the multiflagellate swarmers of P. mirabilis metabolic activity was lowered to a level necessary to maintain flagella activity but not bacterial growth.
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Reversible Change of Mating Type in Phytophthora parasitica
More LessIn addition to the original mating type, the opposite mating type appeared in the zoospore population of single isolates of Phytophthora parasitica after long-term storage or chloroneb treatment. Occasionally self-fertile zoospores were also detected, but their self-induction nature was transitory and unstable. Both hormone production and hormone reception were changed in the sexual variants. The results explain the apparent change from cross-induction (‘heterothallic’) to self-induction (‘homothallic’) in P. parasitica after long-term storage and chloroneb treatment, and suggest one possible evolutionary origin of sex in the lower fungi.
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- Short Communications
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Mutants of Bacillus subtilis Affected in the Morphogenesis of Outgrowing Spores
More LessMutants of Bacillus subtilis temperature sensitive in spore outgrowth and showing altered morphology were examined by ultrathin sectioning and electron microscopy. Cells from spores outgrowing at 47 °C were often spherical with incomplete cross-walls. Cells intersected irregularly by randomly distributed cross-walls were also seen. The presence of sublethal doses of the antibiotic Distamycin A restored the ability to grow as rods, but did not completely restore the capacity to synthesize cross-walls in the correct position.
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Oscillatory Accumulation of Catalase during the Cell Cycle of Acanthamoeba castellanii
More LessThe accumulation of catalase in synchronously dividing cultures of Acanthamoeba castellanii, prepared by size selection techniques involving minimal perturbation, was discontinuous. During the cell cycle of 8 h both catalase activity and immunologically determined catalase protein oscillated with a periodicity of about 1 h and a mean trough-to-peak amplitude of 21% of the minimal values. These patterns of enzyme accumulation were not observed in control asynchronous cultures after exposure to identical experimental conditions. The results are discussed suggesting that periodic biosynthesis and degradation occurs during growth and division of this organism.
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Quantitative Analysis of Macrocyst Formation in Dictyostelium discoideum
More LessQuantitative studies are reported on macrocyst formation, the sexual cycle in Dictyostelium discoideum, under conditions in which asexual fruiting body formation is prevented. Light inhibited amoebae of both mating types from participating in macrocyst formation, and amoebae of the mata mating type responded better to a mating stimulus than amoebae of the matA mating type. These results are interpreted in terms of a possible two-way induction system leading to macrocyst formation in D. discoideum.
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- Taxonomy
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Quantitative and Qualitative Studies of Aeromonas salmonicida Bacteriophage
More LessA comprehensive bacteriophage typing scheme for Aeromonas salmonicida, the causal agent of furunculosis in fish, is described. It distinguishes 27 bacterial groups based on sensitivity patterns to 18 bacteriophage isolates. In addition, the sensitivity patterns are shown to reflect the morphological characteristics of the host bacterium. The ‘rough’,‘smooth’ and ‘G-phase’ forms possess different quantities of lipopolysaccharide in the cell wall and this influences bacteriophage attachment. The problems related to these morphological variations are discussed.
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Reproducible Pyrolysis‒Gas Chromatography of Micro-organisms with Solid Stationary Phases and Isothermal Oven Temperatures
More LessEight solid stationary phases were examined for their suitability for pyrolysis-gas chromatography (Py-GC) of micro-organisms. With temperature programming these phases offered little advantage over the traditional liquid phase Carbowax 20M, but at an isothermal analysis temperature of 100 °C their use solved many technical problems. Pyrograms were produced containing small numbers of baseline-resolved peaks which eluted within 8 to 25 min. Four to six specimens per hour could be examined with two pyrolysers attached to one chromatograph oven. When a control organism was used to derive normalized results, pyrograms were reproducible with a second column and a second pyrolyser, suggesting that inter-laboratory reproducibility may be possible.
Five different bacterial genera were well discriminated and some differentiation was achieved between different isolates of Streptococcus mutans, but similarity between pyrograms was unrelated to orthodox taxonomic grouping. The best discrimination was achieved with Chromosorb 104, followed by Chromosorb 101 and Tenax-GC. With solid phases and isothermal oven temperatures Py-GC is a promising technique for microbial identification.
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A Phylogenetic Analysis of Staphylococci, Peptococcus saccharolyticus and Micrococcus mucilaginosus
More LessThe intra- and intergeneric relationships of the genus Staphylococcus, and the phylogenetic position of Peptococcus saccharolyticus and Micrococcus mucilaginosus (Staphylococcus salivarius), were investigated by comparative oligonucleotide cataloguing of 16S rRNA. All the staphylococci investigated form a phylogenetically coherent group at the genus level that, in addition, contains the anaerobic species Peptococcus saccharolyticus. The genus Staphylococcus belongs to the broad Bacillus-Lactobacillus-Streptococcus cluster that is defined by Gram-positive bacteria with a low DNA G+C content.
Micrococcus mucilaginosus is not a genuine member of the genus Micrococcus. The binary matching coefficients between the 16S rRNA of Micrococcus mucilaginosus and those of representatives of the Arthrobacter/Micrococcus group and related genera indicate that Micrococcus mucilaginosus should be regarded as a member of a new genus.
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Volume 40 (1965)
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Volume 39 (1965)
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Volume 38 (1965)
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Volume 37 (1964)
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Volume 36 (1964)
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Volume 35 (1964)
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Volume 34 (1964)
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Volume 33 (1963)
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Volume 32 (1963)
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Volume 31 (1963)
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Volume 30 (1963)
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Volume 29 (1962)
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Volume 28 (1962)
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Volume 27 (1962)
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Volume 26 (1961)
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Volume 25 (1961)
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Volume 24 (1961)
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Volume 23 (1960)
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Volume 22 (1960)
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Volume 21 (1959)
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Volume 20 (1959)
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Volume 19 (1958)
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Volume 18 (1958)
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Volume 17 (1957)
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Volume 16 (1957)
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Volume 15 (1956)
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Volume 14 (1956)
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Volume 13 (1955)
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Volume 12 (1955)
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Volume 11 (1954)
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Volume 10 (1954)
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Volume 9 (1953)
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Volume 8 (1953)
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Volume 7 (1952)
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Volume 6 (1952)
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Volume 5 (1951)
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Volume 4 (1950)
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Volume 3 (1949)
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Volume 2 (1948)
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Volume 1 (1947)