- Volume 133, Issue 4, 1987
Volume 133, Issue 4, 1987
- Biochemistry
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Occurrence of Intracellular Inclusions and Plasmids in Xenorhabdus spp
More LessSUMMARY: Entomopathogenic bacteria of the genus Xenorhabdus produce crystalline inclusion bodies during in vitro culture. When cultured in liquid media, inclusions were present in primary forms but not secondary forms of X. nematophilus. In contrast, both primary and secondary forms of X. luminescens produced inclusion bodies during liquid culture. Two morphologically distinct forms of inclusion bodies were found in X. nematophilus subsp. nematophilus strain All. They were proteinaceous, and one of the proteins (IP-1) was present in seven strains of X. nematophilus subsp. nematophilus, but not in strains of X. nematophilus subsp. poinari, X. nematophilus subsp. poinarii, X. nematophilus subsp. beddingii or X. luminescens. This protein may be useful as a taxonomic indicator. Plasmids were isolated from seven of ten strains of Xenorhabdus. They varied in size from 12 to 3·6 kb, and were present in both primary and secondary forms of X. nematophilus subsp. nematophilus and X. nematophilus subsp. bovienii.
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Alternative Pathways for the Biosynthesis of Alginate from Fructose and Glucose in Pseudomonas Mendocina and Azotobacter Vinelandii
More LessSUMMARY: The incorporation of specifically labelled sugars into alginate by mucoid strains of both Pseudomonas mendocina and Azotobacter vinelandii resulted in substantially different labelling patterns for fructose and glucose. Alginate was synthesized principally from degradation products of glucose, whereas the majority of the polymer produced from fructose was assembled from intact hexose units. A possible explanation for the limited synthesis of alginate from undegraded glucose molecules is that one of the necessary enzymes, glucose-phosphate isomerase, is subject to inhibition by 6-phosphogluconate, a metabolite involved in the catabolism of sugars via the Entner-Doudoroff pathway in both of the organisms.
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Cytochrome P-450 Accumulation and Loss as Controlled by Growth Phase of Saccharomyces Cerevisiae: Relationship to Oxygen, Glucose and Ethanol Concentrations
More LessEthanol induced small amounts of cytochrome P-450 in Saccharomyces cerevisiae NCYC 754 under conditions in which it is not normally detectable. Moreover, in non-growing yeast the existing cytochrome P-450 content was increased by 50 % at a limited range of glucose concentrations (8–12 % in 0·1 m-potassium phosphate buffer, pH 7·0), in which ethanol is produced by fermentation, possibly at an optimum concentration for induction of cytochrome P-450. Added alkanols, other than ethanol, caused rapid degradation of cytochrome P-450 in non-growing yeast; the rate of loss was directly related to the lipid solubility of the alkanol. Ethanol therefore favoured the accumulation of cytochrome P-450 in yeast; this may be related to an important putative role of one of the isoenzymes in ethanol-tolerance of the yeast, by the oxidative removal of ethanol from the endoplasmic reticulum of the cell. It is the accumulation of dissolved oxygen, rather than ethanol, that occurs on cessation of yeast growth that is likely to trigger the rapid disappearance of cytochrome P-450 observed at this time.
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- Biotechnology
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Effect of Carbon Source on Production of Thermostable α-Amylase, Pullulanase and α-Glucosidase by Clostridium Thermohydrosulfuricum
More LessThe anaerobic thermophile Clostridium thermohydrosulfuricum produced thermostable α-amylase, pullulanase and α-glucosidase activities during growth on starch, pullulan, dextrin or maltose. Synthesis of α-amylase and pullulanase was partially repressed by glucose, whereas α-glucosidase synthesis was not. Fructose completely repressed the synthesis of α-amylase and pullulanase but only partially that of α-glucosidase. α-Amylase and pullulanase activities were predominantly located extracellularly. However, during growth on low amounts of soluble starches (2%, w/v) virtually all activity was cell-associated. Under most conditions examined 75% or more of the α-glucosidase activity was cell-bound. The combined action of these activities produced glucose as the final end-product from amylose and pullulan digestions.
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- Development And Structure
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Induction of Autolysis in Streptococcus Faecium
More LessAutolysis of exponential-phase Streptococcus faecium cells was promoted by pretreating the bacteria (freezing-thawing; −70 °C) in Tris buffer, followed by incubation at 37 °C in the same buffer. The effect was dependent on Tris concentration. The pretreatment provoked ultrastructurally visible damage with extensive loss of K+ and leakage of UV-absorbing components. No autolysis was observed when the bacteria frozen-thawed in Tris were incubated in the presence of the autolysin inhibitor N-bromosuccinimide nor when they had been grown in the presence of chloramphenicol or tetracycline. Furthermore, two autolytic-defective mutants, EC31 and EC78, isolated from S. faecium, did not autolyse when frozen-thawed and incubated in Tris. Freezing-thawing in Tris, however, imparted extensive cell damage to the mutants and to the antibiotic-treated bacteria as well as considerable leakage of K+ and UV-absorbing materials. These observations indicate that the lysis of S. faecium reported above is due to the activity of the endogenous bacterial autolysin. Induction of autolysis of S. faecium by freezing-thawing was also observed, although to a lesser extent, when Tris was replaced by imidazole.
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- Ecology
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Competition between Specialist and Generalist Methylotrophic Bacteria for an Intermittent Supply of Methylamine
More LessA computer program, METHCOMP, to simulate the competition between an obligately methylotrophic bacterium, a facultatively methylotrophic bacterium, a bacterium able to use methylamine as nitrogen source only, and a non-methylamine-using bacterium for methylamine and glucose in continuous culture with a constant or alternating nutrient supply is described. Competitions between obligate methylotroph B6/2 and facultative methylotroph DT26 in continuous cultures supplied alternately with methylamine and glucose/ammonium were both simulated using experimentally determined growth parameters and investigated in laboratory mixed cultures. The results of the laboratory experiments were in excellent agreement with the simulations. The composition of the mixed population is predicted to vary with imposed dilution rate, with strain B6/2 excluded at dilution rates below 0·0625 h−1 and strain DT26 excluded at dilution rates above 0·20 h−1. At intermediate dilution rates both strains coexisted in stable proportions which depended upon the dilution rate. Hence, the use of an alternating nutrient supply may offer a practical approach to the control of the composition of defined, mixed microbial populations.
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- Genetics And Molecular Biology
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Cloning of Aminoglycoside-Resistance Determinants from Streptomyces Tenebrarius and Comparison with Related Genes from Other Actinomycetes
More LessAt least two aminoglycoside-resistance determinants from Streptomyces tenebrarius have been cloned separately in Streptomyces lividans. In each case, resistance (to kanamycin plus apramycin or to kanamycin plus gentamicin) was expressed at the level of the ribosome and involved specific methylation of 16S ribosomal RNA. Hybridization and restriction analysis revealed that related genes were present in other aminoglycoside-producing actinomycetes.
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Cloning and Characterization of the Gene Encoding Lipoamide Dehydrogenase in Saccharomyces Cerevisiae
More LessThe LPD1 gene of S. cerevisiae, which encodes lipoamide dehydrogenase (EC 1.8.1.4), has been cloned and characterized. The LPD1 gene is present as a single copy in the yeast genome and is transcribed to give a polyadenylated mRNA species of approximately 2·0 kb. The synthesis of lipoamide dehydrogenase in yeast is subject to carbon catabolite repression since both the level of the LPD1 transcript and the accumulation of the lipoamide dehydrogenase subunit polypeptide were greatly reduced in wild-type cells grown on glucose compared to those grown on a variety of non-fermentable carbon sources. Strains defective in LPD1 but transformed with the LPD1 gene on a high copy number vector exhibited elevated levels of the LPD1 transcript as well as increased lipoamide dehydrogenase activity when grown on glycerol. Immunoblotting experiments confirmed that such transformants over-expressed lipoamide dehydrogenase protein. Transcription from the LPD1 sequence on plasmid pGP1 still appeared to be subject to some catabolite repression despite the presence of multiple copies of the plasmid in the cell.
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Characterization of Glucosyltransferase Expressed from a Streptococcus Sobrinus Gene Cloned in Escherichia Coli
More LessThe gene encoding a glucosyltransferase which synthesized water-insoluble glucan, gtfI, previously cloned from Streptococcus sobrinus strain MFe28 (mutans serotype h) into a bacteriophage λ vector, was subcloned into the plasmid pBR322. The recombinant plasmid was stable in Escherichia coli and gtfI was efficiently expressed. The GTF-I expressed in E. coli was compared to the corresponding enzymes in S. sobrinus strains MFe28 (serotype h), B13 (serotype d) and 6715 (serotype g) and shown to resemble them closely in molecular mass and isoelectric point. The insoluble glucan produced by GTF-I from recombinant E. coli consisted of 1,3-α-d-glycosyl residues (~90%). An internal fragment of the gtfI gene was used as a probe in hybridization experiments to demonstrate the presence of homologous sequences in chromosomal DNA of other streptococci of the mutans group.
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Recombinant Derivatives of Bacillus Subtilis Phage Z Containing the DNA Methyltransferase Genes of Related Methylation-proficient Phages
More LessThe DNA methyltransferase (Mtase) genes of temperate Bacillus subtilis phages SPR, ø3T, SPβ and ρ11 can be transferred by transfection and recombination to the genome of the related nonmodifying phage Z. Integration of the Mtase genes occurs in phage Z DNA at a unique location which is homologous with the flanking regions of the Mtase genes of the related phages. In lysogenic cells carrying recombinant phages, expression of the Mtase genes is repressed, irrespective of whether the Mtase genes were derived from phage donors which were homo- or heteroimmune to phage Z.
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Phage tf-1: A Filamentous Bacteriophage Specific for Bacteria Harbouring the IncT Plasmid pIN25
More LessPhage tf-1 is a filamentous phage which is about 800 nm in length, 10 nm in width and has slightly tapered ends. The phage was isolated from sewage and formed plaques or propagated only on Escherichia coli, Salmonella typhimurium and Klebsiella oxytoca strains harbouring the IncT plasmid pIN25 at 30 ° It adsorbed in large numbers to pIN25-encoded long thick flexible conjugative pili formed at 30° and also to the short form of these pili synthesized at 37 ° The reason for the failure to form plaques at 37 ° is not known. The adsorption site is a short length of the pilus shaft extending 100–200 nm back from the distal tip. Efficient phage tf-1 adsorption to the same site was found for pili determined by other IncT plasmids in spite of the fact that phage tf-1 did not plate or propagate on strains harbouring them. However, areas of specific partial clearing on lawns of these plasmid-containing bacteria were produced by phage in high concentrations. Lack of plaque-formation could be due to inefficient intracellular assembly coupled to avid adsorption of any liberated phage to pili. The phage differs from all but one other filamentous phage by being sensitive to diethyl ether.
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DNA Repair Systems in the Phototrophic Bacterium Rhodobacter Capsulatus
More LessUV irradiation and mitomycin C exposure trigger a protease-activity-dependent inhibition of cell division in Rhodobacter capsulatus, which begins about 2 h after the treatment is applied. UV irradiation also induces a dose-dependent mutagenesis with a maximal rate between 5 and 10 J m−2, with increased synthesis of a protein of Mr approximately 30000 between 2 and 3 h after UV irradiation. In addition, R. capsulatus has an efficient photoreactivation system that reverses the lethal effects of UV irradiation in the presence of intense visible light.
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Molecular Cloning and Nucleotide Sequence of the 3-Isopropylmalate Dehydrogenase Gene of Candida Utilis
A 3-isopropylmalate dehydrogenase (3-IMDH, EC 1.1.1.85) gene was cloned from a gene library of Candida utilis. One of the plasmids, pYKL30, could complement Escherichia coli leuB and Saccharomyces cerevisiae leu2 auxotrophs; a 2·2 kb HindIII fragment subcloned in pBR322 could still complement the leuB mutation. Southern hybridization confirmed that this fragment was derived from C. utilis. An open reading frame of 1089 bp that corresponded to a polypeptide of 363 amino acids, one residue shorter than the 3-IMDH of S. cerevisiae, was found in the cloned fragment. The homology between the 3-IMDHs of C. utilis and S. cerevisiae was 76·2 % in nucleotides and 85·4 % in amino acids. In contrast, the homology between the 3-IMDHs of C. utilis and Thermus thermophilus was much smaller and was restricted to some regions of the gene.
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Gluconeogenic Mutations in Pseudomonas Aeruginosa: Genetic Linkage between Fructose-bisphosphate Aldolase and Phosphoglycerate Kinase
More LessMutants of mucoid Pseudomonas aeruginosa defective in fructose-bisphosphate aldolase (FBA), NADP-linked glyceraldehyde-3-phosphate dehydrogenase (GAP) or 3-phosphoglycerate kinase (PGK) were unable to grow on gluconeogenic precursors like glutamate, succinate or lactate. The gap and pgk mutants could grow on glucose, gluconate or glycerol, but fba mutants could not. This suggests that the metabolism of glucose or gluconate does not require either PGK or NADP-linked GAP but does require the operation of the aldolase-catalysed step. For gluconeogenesis, however, all three steps are essential. Recombinant plasmids carrying genes for FBA, PGK, GAP or phospho-2-keto-3-deoxygluconate aldolase (EDA) activities were constructed from a genomic library of mucoid P. aeruginosa selecting for complementation of deficiency mutations. Analysis of their complementation profile indicated that one group of plasmids carried fba and pgk genes, while another group carried eda, 6-phosphogluconate dehydratase (edd) and glucose-6-phosphate dehydrogenase (zwf) genes. The gap gene was not linked to any of these markers. Partial restoration of FBA activity in spontaneous revertants of Fba− mutants was accompanied by a concomitant loss of PGK activity. These experiments indicate a linkage between the fba and pgk genes on the P. aeruginosa chromosome.
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- Pathogenicity And Medical Microbiology
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Localization of Antibody-Binding Sites by Sequence Analysis of Cloned Pilin Genes from Neisseria Gonorrhoeae
More LessSUMMARY: Immunological analysis of gonococcal pilin (the protein structural subunit of pili) has demonstrated the existence of cross-reacting and type-specific epitopes. The role in adhesion of the domains represented by these epitopes remains unclear. DNA sequencing of a series of pilinexpressing (pilE) genes from a number of otherwise isogenic pilus antigenic variants combined with previous immunological analysis of the corresponding encoded pilins has allowed us to correlate certain predicted amino acid sequences with monoclonal antibody reactivities. The putative epitopes for type-specific antibodies lie predominantly in hydrophilic domains that also contain β turns. The epitopes for type-specific monoclonal antibodies were shown to depend on amino acid changes either in three separated blocks of amino acid sequence in the semi-variable (SV) region of pilin, or in discrete regions that lie in the disulphide loop in the hypervariable (HV) region of the polypeptide. In contrast, antibody SMI, which reacts with all gonococcal pili, recognizes a poorly immunogenic region of moderate hydrophilicity but low turn potential lying in a conserved portion of the pilin molecule. Our results confirm that antibodies directed against epitopes in both the SV and HV regions are able to inhibit adhesion.
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Incidence of the Aerobactin Iron Uptake System Among Escherichia coli Isolates From Infections of Farm Animals
More LessSUMMARY: To assess the importance of aerobactin-mediated iron uptake as a bacterial virulence determinant in animal infections, a total of 576 strains of Escherichia coli isolated from cattle, chickens, sheep and pigs were screened by colony hybridization to determine the presence of the aerobactin genetic determinants, and by a bioassay to detect aerobactin secretion in iron-limited conditions. Results obtained by the two complementary methods correlated well. The incidence of the aerobactin system was very high among septicaemia isolates, particularly those from cattle and chickens, an observation that strongly suggests an important role for this mechanism of iron assimilation in pathogenesis. On the other hand, the incidence of the aerobactin system among mastitis strains was not significantly higher than among faecal isolates from healthy animals. No classical enterotoxigenic E. coli strains tested carried the aerobactin genetic determinants. Although most strains that produced aerobactin were also able to make colicin V, the fact that the two characteristics existed separately in a significant minority of isolates suggested that colicin testing alone could not be reliably used to determine the presence of the aerobactin system.
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Interaction of Lactoferrin and Transferrins with the Outer Membrane of Bordetella Pertussis
More LessBordetella pertussis was able to grow in vitro under conditions where the only iron present was bound to the iron-binding proteins ovotransferrin, transferrin or lactoferrin. Under these conditions the bacteria produced neither hydroxamate nor phenolate-catecholate siderophores to assist in the procurement of iron. Examination of B. pertussis outer-membrane preparations by SDS-PAGE and immunoblotting showed that the iron-binding protein ovotransferrin was bound directly to the bacterial surface. Assays of the binding of radiolabelled transferrin by the bacteria showed that the association was a specific process and that there was turnover of the bound proteins. Competitive binding assays indicated that lactoferrin could be bound in the same way. It is suggested that B. pertussis obtains iron directly from host iron-binding proteins during infection.
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Chlamydia Trachomatis (L2 Serovar) Can Be Bound, Ingested and Destroyed by Differentiated but Not by Undifferentiated Human Promyelocyte Cell Line HL-60
More LessAs a model system for analysing interactions between chlamydiae and myeloid cells and their precursors, we have studied binding, ingestion and destruction of Chlamydia trachomatis (L2 serovar) by the human promyelocytic cell line HL-60. HL-60 cells were induced by phorbol myristate acetate (PMA) and dimethyl sulphoxide (DMSO) to differentiate along either the macrophage or the granulocyte pathway, respectively. Using an immunofluorescence assay and electron microscopy, we have shown that induced (differentiated) HL-60 cells, but not uninduced (undifferentiated) HL-60 or other cell lines treated with PMA or DMSO, exhibit increased binding, ingestion and elimination of C. trachomatis; these activities are associated with specific histochemical and antigenic markers of myeloid differentiation. These results suggest that myeloid cells acquire the ability to interact with and kill chlamydiae during cell development.
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Detection of Leptospira Interrogans in Clinical Specimens by in situ Hybridization Using Biotin-Labelled DNA Probes
More LessIn situ DNA hybridization using biotin-labelled leptospiral DNA was performed on clinical specimens to investigate its usefulness as a technique for the identification of Leptospira interrogans. The applicability of this test in blood, urine and liver smears was demonstrated. In situ DNA hybridization can be completed in only 4 h and it combines the advantage of visualization of the leptospiral morphology with the specificity of the hybridization reaction. No cross-hybridization was observed with other bacteria. This study shows that hybridization in situ can be simple to perform and may contribute to a rapid diagnosis.
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Chemical Composition and Immunobiological Activities of Sodium Dodecyl Sulphate Extracts from the Cell Envelopes of Actinobacillus Actinomycetemcomitans, Bacteroides Gingivalis and Fusobacterium Nucleatum
SUMMARY: The chemical composition and immunobiological activities in vivo and in vitro of sodium dodecyl sulphate extracts (SDS-SE) derived from periodontopathic bacteria (three strains of Actinobacillus actinomycetemcomitans, two strains of Bacteroides gingivalis, and one strain of Fusobacterium nucleatum) were investigated. The main components of SDS-SE were protein and lipid, with negligible amounts of peptidoglycan and lipopolysaccharide. Immunopotentiating activity was detected in both delayed-type hypersensitivity and antibody formation against the elicitation of a protein antigen with the SDS-SE preparations of A. actinomycetemcomitans ATCC 29524 and B. gingivalis 381 and 1021. On the other hand the SDS-SE of A. actinomycetemcomitans ATCC 29522 enhanced only the induction of a delayed-type hypersensitivity response. All the SDS-SE preparations had mitogenic activity to splenocytes from BALB/c nu/nu, C3H/HeN and C3H/HeJ mice. Migration-stimulating activity for human peripheral blood monocytes was detected especially in the SDS-SE preparations of A. actinomycetemcomitans ATCC 29524 and Y4. All of the SDS-SE samples inhibited [3H]thymidine uptake in human gingival fibroblasts and caused degradation of the cells. The results suggest that the cell membrane components extractable with sodium dodecyl sulphate from periodontopathic bacteria are involved in the pathogenesis of periodontal disease.
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- Physiology And Growth
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Changes in 45Ca and 109Cd Uptake, Membrane Potential and Cell pH in Saccharomyces cerevisiae Provoked by Cd2+
More LessSUMMARY: The effect of Cd2+ poisoning of Saccharomyces cerevisiae on 45Ca, 109Cd and [14C]tetraphenyl phosphonium (TPP) uptake and cell pH was examined. At Cd2+ concentrations that produced substantial K+ efflux the rates of uptake of 45Ca, 109Cd and [14C]TPP increased progressively during incubation of the cells with Cd2+, and the cell pH was lowered concomitantly. The initial rates of uptake of the divalent cations and of TPP were increased in cells pre-loaded with Cd2+, which shows that stimulation of the ion fluxes was exerted by the Cd2+ that accumulated in the cells. The distribution ratio of TPP between cells and medium, however, was decreased by Cd2+. Although hyperpolarization of the cell membrane by Cd2+ cannot be excluded, it is argued that Cd2+ primarily stimulated divalent cation uptake by increasing the cation permeability of the cell membrane allowing the cations to enter the cells more easily.
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Transport, Nutritional and Metabolic Studies of Taurine in Staphylococci
More LessSUMMARY: A specific, Na+-dependent, energy-requiring transport system for taurine has been reported recently in the Staphylococcus aureus M strain. Taurine was taken up vigorously by all S. aureus strains tested. The system was Na+-dependent, and Na+-decreased the Km but had no effect on the V max of the transport system. Among coagulase-negative staphylococci, the Staphylococcus epidermidis group (a taxonomically related group of species associated with humans or other primates) and the free-living, wide-ranging species Staphylococcus sciuri showed vigorous taurine uptake. Somewhat lower rates were found in the Staphylococcus saprophyticus group. Low or barely detectable uptake rates were noted in other staphylococcal species that were primarily of animal origin. No taurine uptake was detected in a variety of other bacterial species tested. Taurine uptake, which was not Na+-dependent, occurred in a Pseudomonas aeruginosa strain grown on taurine as sole energy, carbon, nitrogen, and sulphur source, but not when it was grown in a gluconate/salts medium. In nutritional studies we were unable to demonstrate a role for taurine as a sulphur source for S. aureus. [1,2-14C]- and [35S]taurine were taken up during overnight growth of cells, and radioactivity was distributed similarly among cellular fractions, indicating that the carbon and sulphur atoms of taurine were not cleaved and had the same fate. We were unable to demonstrate any catabolism of taurine in radiorespirometric experiments to detect evolution of 14CO2 by cells incubated with [1,2-14C]taurine. Thus, we found no evidence for a role of taurine in the energy, carbon and sulphur metabolism of S. aureus.
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Effect of Ethanol on Activity of the Plasma-membrane ATPase in, and Accumulation of Glycine by, Saccharomyces Cerevisiae
More LessSUMMARY: The pH optimum of the ATPase activity in plasma membranes from Saccharomyces cerevisiae NCYC 431 from 8 h cultures was around 65 and that in membranes from organisms from 16 h cultures near 6·0. The K m[ATP] of the enzyme was virtually unaffected by the age of the culture from which organisms were harvested, although the V max of the enzyme in membranes from organisms from 8 h cultures was higher than that for organisms from 16 h cultures. Ethanol noncompetitively inhibited ATPase activity in membranes, although the inhibition constant for the enzyme from organisms from 8 h cultures was lower than that from organisms from 16 h cultures. Glycine accumulation by the general amino acid permease was non-competitively inhibited by ethanol. Inhibition constants were virtually the same for glycine uptake by deenergized organisms from 8 h and 16 h cultures, but under energized conditions the value was greater for organisms from 16 h rather than 8 h cultures. The data indicate that inhibition of plasma-membrane ATPase activity by ethanol could account, at least in part, for inhibition of glycine accumulation by ethanol.
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PQQ-Dependent Production of Gluconic Acid by Acinetobacter, Agrobacterium and Rhizobium Species
More LessSUMMARY: Acinetobacter Iwoffi, Azotobacter vinelandii, Agrobacterium and Rhizobium species contain quinoprotein glucose dehydrogenase apoenzyme (EC 1.1.99.17). Addition to whole cells of pyrrolo-quinoline quinone (PQQ), the prosthetic group of this enzyme, resulted in the production of gluconic acid from glucose. The in vivo reconstitution of apo-glucose dehydrogenase with PQQ was dependent on the presence of Ca2+ or Mg2+. Optimal conditions for reconstitution allowed maximal glucose dehydrogenase activity in the presence of 1–10 nmol PQQ 1−1. Synthesis of the apoenzyme of glucose dehydrogenase was not dependent on glucose in the growth media. The physiological significance of the synthesis of apo-glucose dehydrogenase, as found in a variety of bacteria, is discussed.
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Effects of CO2 on Budding and Fission Yeasts
More LessSUMMARY: The budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe were grown under CO2 pressure. Cell division was inhibited in both yeasts; RNA and protein content per cell declined but DNA continued to be synthesized and, in the case of Sacch. cerevisiae, reached twice the normal level within 24 h. Changes in mean cell volume occurred in both yeasts within 1 h; an increase occurred in the budding yeast while a decrease was observed in the fission yeast. The results suggest that CO2 may exert its influence on cell characteristics through a change in cell volume.
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The Effect of Nocodazole on Cell Cycle Events in the Plasmodial Slime Mould Physarum Polycephalum
More LessThe action of nocodazole on nuclear morphology, DNA replication and thymidine (TdR) kinase activity has been examined in growing and starving plasmodia of the CL strain of Physarum polycephalum. In the growing plasmodium, nocodazole treatment more than 2 h before mitosis began prevented both mitosis and DNA replication from occurring at the normal time and also prevented the increase in TdR kinase specific activity normally associated with the onset of mitosis. Nocodazole treatment less than 2 h before mitosis began allowed the process to begin at the normal time, but it was not completed. A normal increase in TdR kinase specific activity accompanied the abortive mitosis, but only limited DNA replication was detected. A similar effect of nocodazole on the occurrence of DNA synthesis in starving plasmodia was found. Nocodazole treatment of a starved plasmodium re-fed with growth medium indicated that the plasmodium was in the G2 phase of the cell cycle when it became competent to sporulate.
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Relationship Between Cellulolytic Activity and Adhesion to Cellulose in Ruminococcus Albus
More LessSUMMARY: Bacterial adhesion to cellulose was measured for 13 cellulolytic and 10 non-cellulolytic, xylan-utilizing strains of the ruminal bacterium Ruminococcus albus. Radiolabelled bacteria adhering to Whatman CF11 cellulose powder were determined. Adhesion of the cellulolytic strains ranged from 0 to 49% of the added bacteria. Of the non-cellulolytic strains, 9 showed < 1% adhesion, while one strain gave 5% adhesion. For the cellulolytic strains filter paper solubilization ranged from 24 to 100%, while solubilization of CF11 cellulose varied from 0 to 20%. Both cellulolytic and non-cellulolytic strains produced carboxymethylcellulase (CMCase) activity. SDS-PAGE of cell extracts followed by incubation with a gel overlay containing CMC or xylan produced a zymogram of hydrolytic enzyme activity. The cellulolytic strains showed a number of bands of CMCase and xylanase activity. Non-cellulolytic strains possessed fewer bands of activity towards both CMC and xylan. Certain of the enzymes appeared to possess both CMCase and xylanase activity. Bacterial cell surface hydrophobicity was also measured, but no correlation was found between hydrophobicity and adhesion to cellulose.
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Determination of Growth Parameters of Methylamine-using Bacteria
More LessGrowth parameters on methylamine and glucose were determined for obligately methylotrophic bacterium B6/2, facultatively methylotrophic bacterium DT26 and Pseudomonas NB4, which is able to use methylamine as sole nitrogen source but not as sole carbon and energy source. substrate saturation constants were determined by a respirometric method. Values obtained for maximum specific growth rates (h−1), substrate saturation constants (μmol 1−1), yield coefficient as 50 % maximum growth rate [(g dry biomass) mol−1] and maintenance coefficient [mmol (g dry biomass)−1 h−1], respectively, were 0·33, 36, 21·2 and 3·2 for B6/2 with methylamine as sole carbon, energy and nitrogen source, 0·09, 5·1, 15·6 and 1·8 for DT26 with methylamine as sole carbon, energy and nitrogen source, 0·20, 2·5, 94 and 0·70 for DT26 with glucose as sole carbon and energy source and NH+ 4 as sole nitrogen source, and 0·58, 6·1, 67 and 0·63 for NB4 with glucose as sole carbon and energy source and NH+ 4 as sole nitrogen source. Pseudomonas NB4 grew with a maximum specific growth rate of 0·35 with glucose as sole carbon and energy source and methylamine as sole nitrogen source.
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Control of the Mating Competence Rhythm in Chlamydomonas eugametos
More LessGametes of Chlamydomonas eugametos lose their mating competence during the light periods of a 24 h light/dark (LD) cycle, and reacquire it in the dark periods. A diurnal rhythm in sexual agglutinability of the flagella underlies these fluctuations. Under constant environmental conditions the oscillation persists as an endogenous circadian rhythm. Under natural environmental conditions the rhythm is cooperatively driven by endogenous and exogenous signals. Exogenous control includes a decline in agglutinability upon illumination, which can be countered by Diuron, and a rise in agglutinability upon lowering of the temperature. In LD, pronounced fluctuations of the external pH are found that can be blocked by Diuron. The pH rhythm does not interfere with the agglutinability rhythm. The control of other rhythms in Chlamydomonas is discussed. As sexual agglutinability is due to well-characterized agglutinins located on the flagellar membrane, this biological rhythm lends itself to further exploration at the molecular level.
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- Systematics
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Investigation of Variation in Phenotype and DNA Content between Single-conidium Isolates of Single Penicillium Strains
More LessSUMMARY: Variation in phenotypic properties was examined in three strains of closely related fasciculate species of Penicillium using 114 morphological, physiological, and biochemical characters. Thirty-six of these characters showed variation within single-conidium isolates of the same strain. Conidial sizes and nuclear DNA contents were compared using flow microfluorimetry; these results suggested that significant differences in conidial DNA content are associated with phenotypic variation. The taxonomic significance of the results is discussed.
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Differentiation of Shigella by Esterase Electrophoretic Polymorphism
Ph. Goullet and B. PicardSUMMARY: The electrophoretic mobilities of four esterases (A, B, C and I) of 182 strains of Shigella dysenteriae, S. flexneri, S. boydii and S. sonnei were compared to those of 636 strains of Escherichia coli from various origins, including the Alkalescens Dispar group and entero-invasive strains. Discriminant analysis of the distribution of esterases among the strains revealed that Shigella could be distinguished from E. coli by differences in the distribution of allozymes of esterases C and I. Principal components analysis distinguished four major clusters of Shigella strains corresponding to the following: S. dysenteriae serotype 1; S. flexneri serotypes 1 to 5; S. flexneri serotype 6 and S. boydii serotypes 2 and 4; and S. sonnei. The last three were characterized by distinct electrophoretic variants of carboxylesterase B, as judged by the two-dimensional electrophoretic profile and titration curves. The distinct esterase pattern obtained for the strains of S. boydii serotype 13 substantiates the view that this serotype may constitute a new species.
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Long-chain Fatty Acid Compositions of Some Asporogenous Yeasts and Their Respective Ascosporogenous States
More LessSUMMARY: Long-chain fatty acid compositions were determined for strains of seven species of Candida and their counterparts within the perfect genera: Candida shehatae and Pichia stipitis, Candida kefyr and Kluyveromyces marxianus, Candida lipolytica and Yarrowia lipolytica, Candida pelliculosa and Hansenula anomala, Candida pseudotropicalis and Kluyveromyces fragilis, Candida utilis and Hansenula jadinii, Candida parapsilosis and Lodderomyces elongisporus, Candida shehatae and Pichia stipitis. Close correlations were found between the fatty acid compositions of these pairs of strains, indicating that the analysis of long-chain fatty acids may be useful for studying the relationships between the perfect and imperfect states of the genus Candida.
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- Corrigendum
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Volumes and issues
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Volume 170 (2024)
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Volume 169 (2023)
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Volume 168 (2022)
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Volume 167 (2021)
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Volume 166 (2020)
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Volume 165 (2019)
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Volume 164 (2018)
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Volume 163 (2017)
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Volume 162 (2016)
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Volume 161 (2015)
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Volume 160 (2014)
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Volume 159 (2013)
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Volume 158 (2012)
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Volume 157 (2011)
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Volume 156 (2010)
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Volume 155 (2009)
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Volume 154 (2008)
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Volume 153 (2007)
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Volume 152 (2006)
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Volume 151 (2005)
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Volume 150 (2004)
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Volume 149 (2003)
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Volume 148 (2002)
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Volume 147 (2001)
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Volume 146 (2000)
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Volume 145 (1999)
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Volume 144 (1998)
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Volume 143 (1997)
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Volume 142 (1996)
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Volume 141 (1995)
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Volume 140 (1994)
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Volume 139 (1993)
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Volume 138 (1992)
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Volume 137 (1991)
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Volume 136 (1990)
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Volume 135 (1989)
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Volume 134 (1988)
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Volume 133 (1987)
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Volume 132 (1986)
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Volume 131 (1985)
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Volume 130 (1984)
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Volume 129 (1983)
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Volume 128 (1982)
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Volume 127 (1981)
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Volume 126 (1981)
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Volume 125 (1981)
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Volume 124 (1981)
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Volume 123 (1981)
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Volume 122 (1981)
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Volume 121 (1980)
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Volume 120 (1980)
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Volume 119 (1980)
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Volume 118 (1980)
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Volume 117 (1980)
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Volume 116 (1980)
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Volume 115 (1979)
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Volume 114 (1979)
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Volume 113 (1979)
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Volume 112 (1979)
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Volume 111 (1979)
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Volume 110 (1979)
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Volume 109 (1978)
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Volume 108 (1978)
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Volume 107 (1978)
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Volume 106 (1978)
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Volume 105 (1978)
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Volume 104 (1978)
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Volume 103 (1977)
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Volume 102 (1977)
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Volume 101 (1977)
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Volume 100 (1977)
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Volume 99 (1977)
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Volume 98 (1977)
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Volume 97 (1976)
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Volume 96 (1976)
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Volume 95 (1976)
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Volume 94 (1976)
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Volume 93 (1976)
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Volume 92 (1976)
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Volume 91 (1975)
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Volume 90 (1975)
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Volume 89 (1975)
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Volume 88 (1975)
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Volume 87 (1975)
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Volume 86 (1975)
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Volume 85 (1974)
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Volume 84 (1974)
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Volume 83 (1974)
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Volume 82 (1974)
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Volume 81 (1974)
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Volume 80 (1974)
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Volume 79 (1973)
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Volume 78 (1973)
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Volume 77 (1973)
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Volume 76 (1973)
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Volume 75 (1973)
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Volume 74 (1973)
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Volume 73 (1972)
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Volume 72 (1972)
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Volume 71 (1972)
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Volume 70 (1972)
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Volume 69 (1971)
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Volume 68 (1971)
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Volume 67 (1971)
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Volume 66 (1971)
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Volume 65 (1971)
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Volume 64 (1970)
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Volume 63 (1970)
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Volume 62 (1970)
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Volume 61 (1970)
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Volume 60 (1970)
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Volume 59 (1969)
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Volume 58 (1969)
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Volume 57 (1969)
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Volume 56 (1969)
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Volume 55 (1969)
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Volume 54 (1968)
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Volume 53 (1968)
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Volume 52 (1968)
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Volume 51 (1968)
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Volume 50 (1968)
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Volume 49 (1967)
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Volume 48 (1967)
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Volume 47 (1967)
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Volume 46 (1967)
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Volume 45 (1966)
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Volume 44 (1966)
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Volume 43 (1966)
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Volume 42 (1966)
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Volume 41 (1965)
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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)