- Volume 134, Issue 2, 1988
Volume 134, Issue 2, 1988
- Biochemistry
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The Interaction between Methanol Dehydrogenase and Cytochrome c in the Acidophilic Methylotroph Acetobacter methanolicus
More LessAcetobacter methanolicus contains only c- and b-type cytochromes. One of the b-type cytochromes is probably an o-type oxidase. During growth on methanol at pH 4 the soluble cytochromes c are induced fivefold compared with growth on glycerol. A. methanolicus contains a methanol dehydrogenase (MDH) that is more stable to low pH values than other quinoprotein MDHs but is similar in other respects. Its electron acceptor is an autoreducible cytochrome c L which differs from others in this class in being reduced at pH 4 by MDH in the presence of methanol and in being autoreduced at relatively low pH (pH 7·0). MDH-stimulated autoreduction occurs at the pH of the periplasm (pH 4·0) as predicted if the process of autoreduction is of physiological importance, and the rate is fast enough not to be rate-limiting in electron transport from methanol to the electron transport chain.
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Purification and Properties of Trimethylamine N-Oxide Reductase from Shewanella sp. NCMB 400
More LessTwo major trimethylamine-N-oxide reductases were detected in the periplasmic fraction of the marine bacterium Shewanella sp. NCMB 400 grown in the presence of trimethylamine N-oxide (TMAO). The high-M r enzyme was purified to homogeneity and consisted of a single polypeptide of M r 86000 as judged by SDS-PAGE. The second enzyme had an M r of 47000. On isoelectric focusing, multiple forms of the purified enzyme were revealed with isoelectric points of 5·1 and 5·2. The K m values for the N-oxides of trimethylamine, pyridine and γ-picoline were 0·02, 2·41 and 6·95 mm, respectively. The purified TMAO reductase is a molybdoenzyme containing 1·32 mol Mo (mol enzyme)−1.
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The Secreted Antigens of Mycobacterium tuberculosis and Their Relationship to Those Recognized by the Available Antibodies
Proteins secreted by strains of Mycobacterium tuberculosis during short-term, zinc-sufficient batch culture were identified in order to define antigens likely to be relevant to the pathogenesis of human disease. [35S]Methionine-labelled proteins in supernatants of 4-7 d cultures were separated by PAGE under both denaturing and non-denaturing conditions, and the position of labelled material was determined. Secreted protein patterns of M. tuberculosis were quite similar to those of Bacillus Calmette-Guérin (BCG) but differed by the absence of the 46 kDa dimeric protein specific to BCG and by the presence in large amounts of a 23 kDa protein which, when denatured, gave 13 kDa subunits. This 13 kDa subunit protein constituted up to 20% of secreted proteins in classical strains of M. tuberculosis of phage type B but was not detected in phage type I strains from South India. This may be relevant to the different pathogenicity of these strains. Western blot analysis showed that antigens defined in supernatants of short-term (3 d) cultures of M. tuberculosis constituted a small subset of those seen in supernatants of organisms cultured for longer periods. One of the secreted proteins has the interesting property of binding to fibronectin. The available monoclonal antibodies and antisera have been used to identify lines on immunoblots corresponding to the secreted/released antigens of M. tuberculosis. The present findings suggest that there are major secreted antigens to which antibodies do not yet appear to have been produced experimentally.
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- Genetics And Molecular Biology
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Genetic Regulation of the Quinic Acid Utilization (QUT) Gene Cluster in Aspergillus nidulans
More LessA large number of quinic acid non-utilizing qut mutants of Aspergillus nidulans deficient in the induction of all three quinic acid specific enzymes have been analysed. One class, the qutD mutants, are all recessive and are non-inducible at pH 6·5 due to inferred deficiency in a quinate ion permease. Two regulatory genes have been identified. The QUTA gene encodes an activator protein since most qutA mutants are recessive and non-inducible although a few fully dominant mutants have been found. The QUTR gene encodes a repressor protein since recessive mutations are constitutive for all three enzyme activities. Rare dominant non-inducible mutants which revert readily to yield a high proportion of constitutive strains are inferred to be qutR mutants defective in binding the inducer. The gene cluster has been mapped in the right arm of chromosome VIII in the order: centromere − >50 map units − ornB − 12 map units qutC (dehydratase) − 0·8 map units qutD (permease), qutB (dehydrogenase), qutE (dehydroquinase), qutA (activator) − 4·4 map units − qutR (repressor) − 20 map units galG. This organization differs from that of the qa gene cluster in Neurospora crassa, particularly in the displacement of qutC and qutR.
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Aspects of the Regulation of Adenylate Cyclase Synthesis in Escherichia coli K12
A. Roy, P. Glaser and A. DanchinIn Escherichia coli K12 expression of the adenylate cyclase gene is subject to multiple controls. In order to gain understanding of the regulation of adenylate cyclase synthesis, operon and protein fusions were constructed by in vitro recombination either into bacteriophage λ or low-copy-number plasmids, or directly on the chromosome at the cya locus. The fusions were used in physiological experiments as probes to study transcriptional and translational controls of cya expression. It was found that adenylate cyclase synthesis was insensitive to glucose effects. As already described by other workers, the CAP-cAMP complex had a moderate negative control on cya expression. In addition it was observed that concomitant with a severe slackening of growth rate, specific to the growth of cya strains in rich medium, cya expression was considerably enhanced. This increase of adenylate cyclase synthesis did not appear to be directly dependent on the presence of a functional cAMP receptor (CAP), and seemed to be controlled at the level of transcription. Finally, translation of the cya message was very weak when compared to cya transcription (the mRNA level was the same in protein and operon fusions).
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Genetic Analysis in Streptomyces ambofaciens
More LessA chromosomal linkage map of ten markers was established for Streptomyces ambofaciens by the four-factor cross method and allele-gradient analysis. Mutants were obtained by nitrous acid treatment as well as by UV mutagenesis. The fertility of crosses was enhanced over 100-fold by pSAM2, a plasmid present in some strains of S. ambofaciens, and over 1000-fold by the conjugative plasmid pIJ303.
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A Transposon Insertion in the Escherichia coli uvrC Gene; UvrC Protein is Absolutely Required for the Incision Step in Excision Repair
More LessThe formation of single-stranded breaks in DNA following UV irradiation is assessed in uvrC34 mutants. By altering the SOS DNA-repair system, either by additional mutations or by using drugs affecting transcription or translation, it is shown that such single-stranded breaks require one or more DNA-damage-inducible functions. A UV-sensitive strain is characterized as carrying a Tn10 insertion into the uvrC gene. The absence of post-irradiation incision in this strain demonstrates that uvrC function is absolutely required in vivo for the incision stage of excision repair, and suggests that other uvrC mutants are ‘leaky’.
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Transfer of the Ti Plasmid from Agrobacterium tumefaciens into Escherichia coli Cells
More LessWe have screened strains of Agrobacterium tumefaciens for spontaneous mutants showing constitutive transfer of the nopaline Ti plasmid pTiC58 during conjugation. The Ti plasmid derivatives obtained could be transferred not only to A. tumefaciens but also to E. coli cells. The Ti plasmid cannot survive as a freely replicating plasmid in E. coli, but it can occasionally integrate into the E. coli chromosome. However, insertion in tandem of plasmids carrying fd replication origins (pfd plasmids) into the T-DNA provides an indicator for all transfer events into E. coli cells, providing fd gene 2 protein is present in these cells. This viral protein causes the excision of one copy of the pfd plasmid and allows its propagation in the host cell. By using this specially designed Ti plasmid, which was also made constitutive in transfer functions, we found plasmid exchange among A. tumefaciens strains and between A. tumefaciens and E. coli cells to be equally efficient. A Ti plasmid with repressed transfer functions was transferred to E. coli with a rate similar to the low frequency at which it was transferred to A. tumefaciens. The expression of transfer functions of plasmid RP4 either in A. tumefaciens or in E. coli did not increase the transfer of the Ti plasmid into E. coli cells, nor did the addition of acetosyringone, an inducer of T-DNA transfer to plant cells. The results show that A. tumefaciens can transfer the Ti plasmid to E. coli with the same efficiency as within its own species. Conjugational transmission of extrachromosomal DNA like the narrow-host-range Ti plasmid may often not only occur among partners allowing propagation of the plasmid, but also on a ‘try-all’ basis including hosts which do not replicate the transferred DNA.
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Over-production and Characterization of the nifA Gene Product of Klebsiella pneumoniae — the Transcriptional Activator of nif Gene Expression
R. Tuli and M. J. MerrickThe nifA gene of Klebsiella pneumoniae, which encodes the transcriptional activator of nif gene expression, was cloned into a number of plasmid vectors to obtain high-level synthesis of nifA product (NifA). When over-produced, NifA was very insoluble and it precipitated with the cell debris after cell lysis. Localization of β-galactosidase activity from a nifA-lacZ translational fusion confirmed the insoluble nature of NifA. Analysis of two translational fusions in which the last six C-terminal amino acids of NifA were deleted suggests that these residues are required for activity.
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Chromosomal Mapping and Cloning of the Lipase Gene of Pseudomonas aeruginosa
More LessVarious mutants (lip) of Pseudomonas aeruginosa PAO 2302 that lacked extracellular lipase activity were isolated. They were selected on a calcium-triolein agar. The phenotypic characteristics of two of these mutants suggested that they were defective in the gene coding for lipase: both lip mutants produced no lipase in liquid- and on solid medium. They were non-pleiotropic with regard to various other exoproducts. None of the mutants released any putatively cell-bound lipase after treatment of cells with Triton X-100 or alginate. The electrophoretic protein- and LPS-profiles of outer membranes derived from lip mutants and the parental strain were identical. The lip locus was mapped on the chromosome of P. aeruginosa PAO 1 by FP5- and R68.45-mediated crossings and by transduction with phage G101. The lip locus was cotransduced with pyrF only (60%) indicating a map position at about 57 min. The lipase gene was cloned on a 3.1 kb Sal I fragment using vector pKT248. The newly constructed plasmid was able to complement the lipase deficiency of the two lip mutants of P. aeruginosa.
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Mutations Affecting the Synthesis of NADP-dependent Glutamate Dehydrogenase in Pseudomonas aeruginosa
More LessNADP-dependent glutamate dehydrogenase (NADP-GDH) was purified to homogeneity from Pseudomonas aeruginosa strain 8602 (PAC 1). The M r determined by Sephadex gel filtration was 280000; the subunit M r determined by SDS-PAGE was 45000. Mutant strains lacking NADP-GDH and glutamate synthase (Gdh−Glt−) required glutamate for growth. Transductants that lacked only NADP-GDH were indistinguishable from the wild-type strain in growth properties. It was concluded that NADP-GDH is not essential for growth of the wild-type organism and that glutamate formation via NAD-dependent glutamate dehydrogenase does not occur to a significant extent. A mutant strain, 39, producing high NADP-GDH activity, synthesized normal NADP-GDH and had the same intracellular glutamate concentrations as its parent. The mutation responsible for the synthesis of high levels of NADP-GDH was shown, by transduction, to be closely linked to the NADP-GDH structural gene (gdhA).
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Functional Analysis of the Adsorption Protein of Two Filamentous Phages with Different Host Specificities
More LessThe gene 3 coding for one minor coat protein (adsorption protein) of phage IKe was cloned into an expression plasmid and overproduced. The presence of a promoter for this gene could be demonstrated as well as the incorporation of the IKe gene 3 protein (g3p) into the cytoplasmic membrane of host cells. When 110 carboxy-terminal amino acids were deleted, the truncated protein was translocated across the cytoplasmic membrane into the periplasm. Thus the deleted amino acids bear a membrane anchor domain. In contrast to the partly homologous g3p of the Ff phages, IKe g3p did not alter the membrane properties of its host. IKe g3p was not incorporated into Ff phage particles in amounts detectable by our assays although the presence of IKe g3p may affect the efficiency of Ff phage production. The existence of a structural feature necessary for the specific recognition of the respective g3p during phage assembly is deduced.
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A Specific DNA Probe for the Identification of Campylobacter jejuni
More LessA 6·1 kb DNA probe for the human enteric pathogen Campylobacter jejuni has been isolated from a genomic library constructed in the plasmid vector pBR322 in Escherichia coli. The DNA sequence used as a probe was identified from recombinant plasmids following immunological screening of transformants using polyclonal antisera to whole cells and to membrane antigens of C. jejuni. Restriction endonuclease fragment mapping of C. jejuni DNA inserts from three of the recombinant plasmids showed an overlapping DNA fragment. One of these recombinant plasmids, when used as a DNA probe in Southern hybridization, specifically hybridized with chromosomal DNA from all of the C. jejuni strains tested. Hybridization was not detected at high stringency between the DNA probe and chromosomal DNA from any other Campylobacter species tested except weakly with the chromosomal DNA of strains of Campylobacter coli. Hybridization was also not detected with chromosomal DNA from a range of other enteric bacteria likely to be encountered in faecal material. The intensity of hybridization with C. coli could be increased by reducing the stringency of hybridization.
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- Immunology
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Immunological Reaction of Guinea-pigs Following Intranasal Mycoplasma pneumoniae Infection and Immunization with the 168 kDa Adherence Protein
More LessHumoral responses to Mycoplasma pneumoniae proteins, especially the 168 kDa protein, were demonstrated by Western blotting in sera and bronchial washings of all groups of infected or immunized guinea-pigs. However, infection was not prevented by these local and systemic antibodies. Hilar lymphocytes of infected and immunized guinea-pigs were stimulated in vitro by sonicated M. pneumoniae antigen and by the 168 kDa protein. Stimulation was significantly lower in animals which had been infected twice or had been preimmunized and challenged by infection. Histologically the most severe lesions were seen in the twice-infected group followed by the preimmunized group which was subsequently infected.
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- Pathogenicity And Medical Microbiology
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Inactivation of Human α-1-Antitrypsin by a Tissue-destructive Protease of Legionella pneumophila
More LessThree extracellular proteases produced by Legionella pneumophila during growth in liquid medium were examined for their effects on human α-1-antitrypsin (α-1-AT). One of these proteases, tissue-destructive protease (TDP) destroyed completely the trypsin-inhibitory capacity of α-1-AT at protease: inhibitor molar ratios down to 0.002:1. After inactivation by TDP, the M r of α-1-AT was reduced by 5000 in SDS-PAGE. This suggested that inactivation entailed only limited cleavage.
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A Phospholipase C from the Dallas 1E Strain of Legionella pneumophila Serogroup 5: Purification and Characterization of Conditions for Optimal Activity with an Artificial Substrate
More LessPhospholipase C from the Dallas 1E strain of Legionella pneumophila serogroup 5 was purified from buffered yeast extract culture supernate by ion-exchange chromatography followed by fractionation by manganous chloride and ammonium sulphate precipitation steps. Enzyme activity was assayed by hydrolysis of p-nitrophenylphosphorylcholine and confirmed by release of radioactivity from tritiated L-α-dipalmitoylphosphatidylcholine labelled in the methyl groups of choline. After SDS-PAGE, the purified preparation yielded a single band upon Coomassie-blue staining. This protein migrated with an apparent M r of 50000–54000. Phospholipase C activity was maximal at pH ≥ 8.4 and was enhanced in the presence of sorbitol and of several nonionic detergents but was eliminated by SDS. EDTA, Cu2+, Fe2+ and Zn2+ inhibited enzyme activity, whereas Ba2+, Ca2+, Co2+, Mg2+ and Mn2+ restored activity to EDTA-treated material. No haemolytic activity was demonstrated with the purified enzyme.
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Protein Changes Associated with Induced Resistance of Neisseria gonorrhoeae to Killing by Human Serum Are Relatively Minor
More LessSerum-susceptible (SS) Neisseria gonorrhoeae were induced to resistance (SR) to complement-mediated killing by fresh human serum (FHS) by a small-M r factor(s) from guinea-pig blood in 3 h at 37 °C, but not in the presence of bacteriostatic concentrations of chloramphenicol or neomycin, indicating that proteins mediated the acquisition of resistance. SDS-PAGE protein profiles of lysates of equal numbers of gonococci showed only two qualitative differences between SR and SS organisms, both in minor components (a protein A of about 205 kDa in the former and not the latter and vice versa for a protein B of about 16 kDa). Many proteins, however, including the three principal outer-membrane proteins, were present in larger amounts in SR gonococci. The lack of major changes in proteins when resistance is acquired was confirmed by immunoblotting the two protein profiles with the IgG of hyper-immune rabbit anti-SR and anti-SS sera, of rabbit anti-SR serum after absorption by SS organisms and of FHS used alone and after absorption with SS organisms. The IgM of FHS, which is responsible for most of the bactericidal activity, showed only faint reactions with a few proteins common to both SS and SR gonococci and no reactions when the FHS was absorbed with SS gonococci. This is in contrast to the strong and different reactions given with lipopolysaccharide (LPS) components of SS and SR organisms, which, prepared from the former organisms, neutralize the bactericidal activity of FHS. Hence, the relatively small protein changes accompanying induction are less likely to be directly responsible for serum resistance than the more profound LPS changes.
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Rapid Damage to Membranes of Neisseria gonorrhoeae Caused by Human Neutrophil Granule Extracts
More LessNeisseria gonorrhoeae were exposed to extracts of human neutrophil granules and effects on gonococcal growth and membranes were determined. Enumeration of gonococci by phase-contrast microscopy at 0 and 60 min revealed that they underwent very limited cell division after exposure to granule extract. At 60 min, treated gonococci tended to clump, and some lost their refractivity under phase-contrast optics, indicating membrane damage. Treated and untreated gonococci utilized oxygen at similar rates at time 0; treated gonococci utilized oxygen at a relatively constant rate for 60 min, even though colony-forming ability (i.e. viability) decreased by 90%, whereas untreated gonococci showed a steadily increasing rate of oxygen consumption over the same period, which essentially paralleled increase in colony-forming ability. Membrane ultrastructure of untreated and treated gonococci was compared in thin section by transmission electron microscopy. Extract treatment resulted in a time-related increase in disruption of the bacterial outer membrane, which became apparent almost immediately after treatment. This was accompanied by increasingly aberrant septum structure. Extract treatment also increased the resolution of peptidoglycan by electron microscopy, as early as 10 min after treatment. These data suggest that extract treatment of gonococci caused a rapid loss of the ability to form colonies on agar concomitant with alteration of gonococcal peptidoglycan and outer-membrane structure, but with little alteration of inner-membrane function.
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- Physiology And Growth
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Temperate Phages and Bacteriocins of the Gliding Bacterium Cytophaga johnsonae
More LessA collection of 30 independently isolated strains of Cytophaga johnsonae was screened for the presence of temperate bacteriophages. Two strains were found to harbour phages. The newly isolated phages differ in several respects from the 43 previously isolated phages for C. johnsonae. Both phages are polyhedral, approximately 60 nm in diameter, and have no apparent tail structure. They are chloroform sensitive, and plaque formation is inhibited by agar. Both are capable of establishing a stable association with host cells. Twenty-nine of the 30 strains produced diffusible substances that specifically inhibited the growth of other C. johnsonae strains or closely related species and that could not be propagated. These substances appear to be bacteriocins, some of which, like bacteriophages, are active only against motile cells, while others inhibit nonmotile as well as motile cells. One of each of these two types of bacteriocins was partially characterized and both were found to be proteinaceous in nature and bactericidal in effect.
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Monoclonal Antibodies against a Protein Missing from Nonmotile Mutants of the Gliding Bacterium Cytophaga johnsonae
More LessTo identify components of the gliding bacterium Cytophaga johnsonae that are involved in gliding motility, we generated hybridomas that produced monoclonal antibodies (MAbs) against membranes from wild-type cells and screened for MAbs that failed to bind to cells of nonmotile mutants. Of 22 hybridomas generated, three produced MAbs that were positive in ELISA with wild-type cells or their membranes and were negative in ELISAs with 57 of 63 mutants tested. Immunoblots of polyacrylamide gels of wild-type membrane proteins showed that all three of these motility-related MAbs recognized the same antigen: a 40 kDa major membrane protein of wild-type cells. Immunoblots of nonmotile mutant cells and membranes showed that those giving negative ELISA results with the three MAbs actually produced the protein, but in only trace amounts compared with the parental strain. These results show that synthesis of the 40 kDa protein is related somehow to the ability of the cells to move, but the nature of the relationship is still unknown. The protein may be required for motility, or regulation of its synthesis and assembly may be linked to motility although it has no direct role in motility. Results of other experiments on the distribution of an immunologically related protein among other gliding bacteria and on the effects of the three motility-related MAbs on gliding of C. johnsonae did not distinguish between these two possibilities.
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The Surface Layer of Mycoplasma mobile 163K and Its Possible Relevance to Cell Cohesion and Group Motility
More LessMycoplasma mobile strain 163K tends to move in multicellular configurations, either as pairs or small groups of three or more cells, or as chain-like aggregations or microcolonies. Such wandering groups arise by transient association of independently moving cells. This behaviour of M. mobile was microscopically investigated and documented by sequences of microcinematographic pictures, as well as by photomicrographically recorded motility tracks. The presence of an extracellular slime layer was demonstrated in thin sections, by negative staining and by scanning electron microscopy. The possible association of this layer with the cohesive properties of the mycoplasma cells, enabling the formation of wandering groups, is discussed and a calculation of the magnitude of the cohesive force is provided.
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Induction of a Stable Morphological Change in Propionibacterium freudenreichii
More LessWhen cells of Propionibacterium freudenreichii were incubated under fasting conditions and then plated in the presence of an inhibitor of protein synthesis, a variable but significant (>10−2) fraction of the population changed their morphology from rod to sphere, with a considerable thickening of the cell wall. This change was accompanied by metabolic and antibiotic-resistance modifications, including the synthesis of at least one new enzyme (α-glucosidase), and by the simultaneous appearance of several new species of DNA, presumably plasmids. The round cells grew faster than the parent strain and maintained their morphology indefinitely when propagated on complex medium containing glucose as the main carbon source. However, when glucose was omitted, cells returned to the rod form and regained their previous characteristics, including the absence of detectable plasmids.
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Cyanophycin Granule Size Variation in Aphanocapsa
More LessTechniques were developed for the rapid and simple electron microscopic visualization of isolated cyanophycin granules to allow analysis of their size from cells grown under different conditions. Granules were purified by differential and renografin density-gradient centrifugation from cells grown for various times in chloramphenicol-containing media, or in nitrogen-limited media to which nitrogen was then added back, or under light limitation. Granules were then observed by electron microscopy after staining with uranyl acetate, and random granule diameters were measured. Granule size increased significantly with time following chloramphenicol treatment and following light limitation. This suggests that much of the increase in amount of cyanophycin in cells treated with chloramphenicol or light limitation is caused by increase in granule size rather than in granule number. Insignificant changes in granule size were observed during nitrogen repletion, suggesting increase in granule number, not size.
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A Study of the Role of the Hexose Monophosphate Pathway with Respect to Fatty Acid Biosynthesis in Sporulation of Saccharomyces cerevisiae
More Less13C NMR was used to study the pattern of label incorporation from [2-13C]acetate into trehalose during sporulation in Saccharomyces cerevisiae. A wild-type strain and a strain homozygous for the zwf1 mutation (which affects glucose-6-phosphate dehydrogenase) were used. In the wild-type it was possible to deduce the cycling of glucose 6-phosphate around the hexose monophosphate pathway whilst in the mutant strain this did not occur. The requirement of the hexose monophosphate pathway for providing NADPH for fatty acid biosynthesis was examined using 13C NMR and GC/MS. The wild-type strain produced a typical profile of fatty acids with palmitoleic acid being the most abundant whereas the mutant contained only one-quarter the amount of total fatty acid. As zwf1 homozygous diploids are able to sporulate this indicates that the large amount of fatty acid biosynthesis observed in sporulation of wild-type strains is not essential to the process.
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Lipid Turnover in Oleaginous Yeasts
More LessWhen eight strains of the oleaginous yeasts Candida curvata, Lipomyces starkeyi, Rhodosporidium toruloides and Trichosporon cutaneum were starved of carbon after having accumulated lipid up to 34% of their biomass, the lipid was readily converted to new biomass in all cases except the two strains of L. starkeyi. When C. curvata D was grown in a two-stage chemostat with the second stage as a carbon-starvation vessel (but containing NH+ 4) biosynthesis of new biomass reached 1·9 ± 0·2 g per g lipid utilized. Experiments in a single-stage chemostat undergoing transition from lipid accumulation (nitrogen-limited medium) to carbon-starvation conditions showed that the lipid in C. curvata was rapidly mobilized. When the lipid was pre-labelled with 14C, a transitory pool of rapidly metabolizable non-lipid material appeared within 1.5 h of the initiation of starvation. Rates of lipid loss indicated that initiation of lipid degradation occurred immediately carbon was lost from the external medium.
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Arachidonic Acid from Fungi Utilizing Fatty Acids with Shorter Chains as Sole Sources of Carbon and Energy
More LessSeveral species of soil fungi, belonging to the genera Aspergillus, Penicillium, Fusarium, Paecilomyces, Trichoderma, Cladosporium and Stachybotrys could utilize caprylic, myristic, palmitic, stearic and oleic acids, as well as their sodium salts, as sole sources of carbon and energy. None of the fungal isolates showed any particular specificity to a given fatty acid. Only the caprylic acid utilizers grew poorly, otherwise the growth was fair to abundant. The optimal fatty acid concentration for fungal growth was 10 g l−1. Growth yields were comparable with those on glucose. The optimal pH values were in the region of neutrality and the isolates could tolerate high acidity. Lipids from fungi grown on fatty acids or their sodium salts contained free fatty acids as the predominant lipid class. Such lipids were much richer in arachidonic acid than those from the same fungi grown on glucose. Fungi that contained the highest levels of arachidonic acid were those grown on myristic and palmitic acids, namely Aspergillus versicolor and Aspergillus ustus, respectively.
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Aminochelin, a Catecholamine Siderophore Produced by Azotobacter vinelandii
More LessA catecholamine siderophore, named aminochelin, produced by iron-limited Azotobacter vinelandii was purified and tentatively identified as 2,3-dihydroxybenzoylputrescine. This compound was first observed as an ethyl-acetate-insoluble catechol that accounted for 30 to 50% of the total catechol in iron-limited culture supernatant fluids. The purified compound was unstable at neutral to alkaline pH, bound Fe3+, Fe2+ and molybdate, and promoted 55Fe-uptake into iron-limited A. vinelandii. Aminochelin was induced and repressed coordinately with the other catechol siderophore azotochelin. The catechol siderophores were, however, less sensitive to repression by soluble iron than the yellow-green fluorescent peptide siderophore azotobactin.
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- Systematics
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Rhodothermus marinus, gen. nov., sp. nov., a Thermophilic, Halophilic Bacterium from Submarine Hot Springs in Iceland
More LessThermophilic, reddish-coloured heterotrophic bacteria different from Thermus were isolated from submarine alkaline hot springs in Iceland. The bacteria were obligately aerobic, moderately halophilic, Gram-negative rods, about 0.5 m in diameter and 2-2.5 m long. Neither spores, flagella nor lipid granules were observed, but a slime capsule was formed on carbohydrate-rich medium. Optimum growth was at 65C, pH 7.0, and at about 2% (w/v) NaCl. The bacteria were oxidase negative, catalase positive and contained a carotenoid pigment with the main absorbance peak at 476 nm and shoulders at 456 and 502 nm. The GC content of the DNA was about 64 mol%. Electron micrographs clearly showed an outer membrane, about 9 nm thick, and the cytoplasmic membrane together with the peptidoglycan layer was about 14 nm in thickness. The isolates were nutritionally different from Thermus. They utilized several common sugars but glutamate and aspartate were the only amino acids that most strains used. These bacteria are considered to represent a new genus which we name Rhodothermus, with the type species Rhodothermus marinus.
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DNA:DNA Reassociation Analysis of Aeromonas salmonicida
More LessDNA from 26 Aeromonas salmonicida strains, namely 11 ‘typical’ and 15 so-called ‘atypical’ strains, was used to assess the taxonomic relatedness within the species. The genomes were characterized by determination of DNA base composition, DNA:DNA reassociation, calculation of sequence divergence following reassociation, and by genome size estimations. By comparison with DNA obtained from controls and the Aeromonas hydrophila group, A. salmonicida strains were determined to be correctly placed with respect to genus and species. A. salmonicida subspecies salmonicida (the ‘typical’ group) was an extremely homogeneous taxon. The ‘atypical’ strains were more diverse, but distinct biotypes were recognizable. The first biotype included several geographically diverse isolates from goldfish. The second recognizable biotype included strains isolated from European carp. Other ‘atypical’ isolates could not be grouped but showed enough internal homology to be retained within the species. The A. salmonicida subspecies achromogenes and masoucida were found to be closely related to the motile aeromonads. It is considered that the present classification of A. salmonicida is unsuitable and should be restructured to include A. salmonicida subspecies salmonicida, subspecies achromogenes (to include the present subspecies masoucida), and the reintroduced subspecies nova.
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Characterization of Yersinia enterocolitica, Y. intermedia, Y. aldovae, Y. frederiksenii, Y. kristensenii and Y. pseudotuberculosis by Electrophoretic Polymorphism of Acid Phosphatase, Esterases, and Glutamate and Malate Dehydrogenases
PH. Goullet and B. PicardAcid phosphatase, esterases, and glutamate and malate dehydrogenases of 192 strains of Yersinia enterocolitica, Y. intermedia, Y. aldovae, Y. frederiksenii, Y. kristensenii and Y. pseudotuberculosis were analysed by horizontal polyacrylamide agarose gel electrophoresis and by isoelectrofocusing in thin-layer polyacrylamide gels. The six species were clearly separated from each other by their distinct enzyme electrophoretic polymorphism. For Y. enterocolitica, the strains of biotype 5 were differentiated from the other biotypes by the mobility of glutamate dehydrogenase. For Y. frederiksenii, six zymotypes were delineated by pI and by the mobility of the enzymes. Variation in number or mobility of esterases within each species could represent a marker for epidemiological and ecological analyses. A linear relationship was obtained between the mean genetic diversity coefficient of enzymes and the mean percentage DNA-DNA relatedness of Y. intermedia, Y. aldovae, Y. enterocolitica and Y. frederiksenii.
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Characteristics of Glutamate Dehydrogenase, a New Diagnostic Marker for the Genus Fusobacterium
More LessEnzymes representative of carbohydrate and nitrogen metabolism were screened for their presence and activity amongst species of the genus Fusobacterium. Glutamate dehydrogenase (GDH) was reliably detected in all 25 strains studied. The pH profile of this enzyme and the DNA base composition of selected strains were also determined. DNA base composition of selected strains ranged between 28-32.9 mol% G + C. GDH was active between pH 7.5-11.5 but two pH profiles of activity, with optima at 9.5 and 10.5, were discernible among species. Apart from Fusobacterium nucleatum, which had a heterogeneous enzyme pattern, the GDH electrophoretic mobility was constant within a species but in a few cases the enzyme bands overlapped. A combination of the pH profile, the GDH electrophoretic pattern and the DNA base composition provided clear separation of the test organisms into discrete groups; however, a larger number of strains must be examined before the full potential of these tests can be evaluated.
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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)