- Volume 131, Issue 12, 1985
Volume 131, Issue 12, 1985
- Biochemistry
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Metabolism of 3-Butyn-1-ol by Pseudomonas BB1
More LessSummary: A degradation pathway for the acetylenic compound 3-butyn-1-ol by a bacterium showing strong resemblance to the physiologically well characterized Pseudomonas AM1 is presented. Enzyme studies revealed that the pathway of 3-butyn-1-ol metabolism involves an initial oxidation of the alcohol group by a phenazine methosulphate dependent alcohol dehydrogenase. Subsequently, the aldehyde is probably oxidized to yield 3-butynoic acid. The latter product is hydrated in the absence of cofactors to give acetoacetate which, in turn, is further degraded via acetoacetyl-CoA to acetyl-CoA. The inducible hydration reaction was catalysed by a nonspecific enzyme; hydration of propynoic acid resulted in the formation of malonic semialdehyde.
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Monomeric and Dimeric Quinoprotein Alcohol Dehydrogenase from Alcohol-grown Pseudomonas BB1
More LessSummary: Pseudomonas BB1, grown on alcohols, contained a quinoprotein alcohol dehydrogenase, whose substrate specificity was between those of typical methanol dehydrogenases and ethanol dehydrogenases, and which had a higher turnover number and a different amino acid composition. The enzyme occurred in a dimeric as well as in a monomeric form, and the ratio in which the two forms were found depended on the culture conditions. The mechanism of action and the substrate specificity and affinity of the two forms were identical, while the turnover number of the dimer was twice that of the monomer. This indicates that the catalytic activity of the monomer does not change on dimerization. On inactivating alcohol oxidation of whole cells with cyclopropanol, monomeric and dimeric enzyme became fully inactivated. It is tentatively concluded that both forms participate in alcohol oxidation in vivo.
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Glutamine Cycling in Neurospora crassa
More LessSummary: The accumulation of amino acids and the excretion of ammonium have been studied in various Neurospora crassa ammonium assimilation mutants, together with the labelling of glutamine in the presence of [U-14C]sucrose when N. crassa grows on glutamine as the nitrogen source. Ammonium coming from glutamine degradation by the ω-amidase pathway is assimilated by NADP-dependent glutamate dehydrogenase and glutamine synthetase. The operation of these enzymes results in a cycling of glutamine that seems to be essential for cell growth. In addition, glutamine is also converted to glutamate by glutamate synthase.
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Pyoverdine Production by Pseudomonas fluorescens in Synthetic Media with Various Sources of Nitrogen
More LessSummary: The influence of the nitrogen source on pyoverdine production by Pseudomonas fluorescens grown in chemostat culture in synthetic media at constant pH was studied. Pigment synthesis was highest in a medium with proline as the nitrogen source; other amino acids were less effective in promoting pigment synthesis. The pH and Fe3+ content of the media affected pyoverdine production. The ratio of pigment to growth was maximal at pH 8. When the Fe3+ concentration was increased from 10 to 200 μg 1−1 in media with the same nitrogen source, pyoverdine synthesis decreased. Since the Fe3+ contents of the synthetic media were different, the amount present was adjusted to a standard concentration to permit comparisons between the various nitrogen sources.
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Measurement of ATP Generation and Decay in Mycobacterium leprae in vitro
More LessSummary: The intracellular ATP content of Mycobacterium leprae isolated from armadillo tissue was approximately 1.5 x 10−16 g per bacillus. During in vitro incubation of bacilli at 4 °C, 33 °C or 37 °C there was an exponential decrease in ATP content, the rate depending on the medium and the temperature. M. leprae incorporated phosphate into ATP and into other nucleotide materials during in vitro incubation.
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Purification and Properties of a Cellulase from Alkalophilic Bacillus sp. No. 1139
More LessSummary: An alkalophilic Bacillus sp., no. 1139, was isolated from soil and this bacterium produced a carboxymethyl cellulase (CMCase). The production of enzyme was strongly inhibited by the addition of glucose. The CMCase was purified on a DEAE-Toyopearl 650 ion-exchange column followed by Toyopearl HW-55F gel filtration and passage through a DEAE-Toyopearl 650 ion-exchange column. The purified enzyme gave a single band of protein on PAGE. The enzyme hydrolysed carboxymethylcellulose with an optimum at pH 9.0 and a K m of 0.48 mg ml−1; no activity was observed at pH 6.0. The enzyme had a molecular weight (SDS-PAGE) of 92000 and an isoelectric point of 3.1. The maximum degree of hydrolysis of carboxymethylcellulose was about 30% and trans-glucosidase activity was also observed.
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Purification and Properties of Extracellular Glucosyltransferase Synthesizing 1,6-, 1,3-α-D-Glucan from Streptococcus mutans Serotype a
More LessSummary: An extracellular glucosyltransferase (sucrose: 1,6-, 1,3-α-D-glucan 3-α- and 6-α-D-glucosyltransferase, EC 2.4.1.-) of Streptococcus mutans HS6 (serotype a) was purified from culture supernatant by DEAE-Sepharose chromatography and preparative isoelectric focusing. The molecular weight measured by SDS-PAGE was 159000 and the isoelectric point was pH 4.9. The specific activity was 89.7 i.u. (mg protein)−1 and the optimum pH was 6.0. The K m value for sucrose was 4.9 mM and the enzyme activity was not stimulated by exogenous dextran T10. Glucan was synthesized de novo from sucrose by the purified enzyme and consisted of 49.1 mol% 1,6-α-linked glucose and 33.9 mol% 1,3-α-linked glucose, with 13.6 mol% terminal glucose and 3.3 mol% 1,3,6-α-branched glucose.
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- Biotechnology
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Investigation of the Instability of Plasmids Directing the Expression of Met-Prochymosin in Escherichia coli
More LessSummary: The causes of the instability of a multicopy plasmid, pCT70, which directs the expression of calf prochymosin in Escherichia coli, were investigated. Plasmid pAT153 and its derivative, pCT54, were stable for more than 90 generations in continuous culture with glucose limitation. The multicopy plasmid pCT66, which expressed very low levels of prochymosin due to poor translational efficiency, and low copy number plasmids which efficiently expressed the prochymosin gene, were also stable. These results indicated that high level translation of the recombinant gene was the cause of the instability of pCT70. The maximum specific growth rate of E. coli(pCT70) was reduced by 30% compared with E. coli(pCT66).
To fulfil the requirements of a production system, a dual origin plasmid with controllable copy number was developed. Both this plasmid (pMG165) and a derivative which contained the prochymosin gene (pMG168) were stable when maintained at low copy number. When the copy number of plasmid pMG168 was increased by putting replication under the control of the λPR promoter and the cI857 temperature sensitive repressor, expression of prochymosin was achieved. This strategy enables large-scale production of prochymosin without the need for antibiotic selection or other methods of preventing plasmid loss.
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- Development And Structure
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Regulation of Cyclic AMP Metabolism by the Incompatibility Factors in Coprinus cinereus
More LessSummary: Adenylate cyclase and phosphodiesterase activities were assayed during the course of sexual reproduction in Coprinus cinereus. High levels of adenylate cyclase activity and low levels of phosphodiesterase activity were found in all dikaryons, in Amut Bmut strains, and in the monokaryotic fruiter Fisc. Corresponding to this, a high level of cAMP was found in these strains. On the other hand, low levels of cAMP were found in semi-compatible heterokaryons (common-A and common-B), and in Amut and Bmut strains, where the events leading to sexual morphogenesis had been switched on only partially. cAMP-binding and cAMP-dependent protein kinase activities were detected in the dikaryons, and in Amut Bmut and Fisc strains, but were negligible in the sexually sterile strains. The results indicated that both A and B factors are involved in the coordinate regulation of adenylate cyclase, phosphodiesterase, and cAMP-dependent protein kinase during fruit body formation.
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Characterization of the Anomalous Infection and Nodulation of Subterranean Clover Roots by Rhizobium leguminosarum 1020
More LessSummary: Anomalous nodulation of Trifolium subterraneum (subterranean clover) roots by Rhizobium leguminosarum 1020 was examined as a model of modified host-specificity in a Rhizobium-legume symbiosis. Consistent with previous reports, these nodules (i) appeared most often at sites of secondary root emergence, (ii) were ineffective in nitrogen fixation and (iii) were as numerous as nodules formed by an effective Rhizobium trifolii strain. R. leguminosarum 1020, grown on agar plates or in the clover root environment, did not bind the white clover lectin, trifoliin A. This strain did not attach in high numbers, and did not induce shepherd's crooks or infection threads, in subterranean clover root hairs. However, R. leguminosarum 1020 did cause branching, moderate curling and other deformations of root hairs. The bacteria probably entered the clover root through breaks in the epidermis at sites of lateral root emergence. The anomalous nodulation was inhibited by nitrate. Only trace amounts of leghaemoglobin were detected in the nodules by Western blot analysis. The nodules were of the meristematic type and initially contained well-developed infection, bacteroid and senescent zones. Infection threads were readily found in the infection zone of the nodule. However, the bacteroid-containing tissue senesced more rapidly than in the effective symbiosis between subterranean clover and R. trifolii 0403. This anomalous nodulation of subterranean clover by R. leguminosarum 1020 suggests a naturally-occurring alternative route of infection that allows Rhizobium to enlarge its host range.
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Formation and Regeneration of Protoplasts from Conidiobolus lamprauges
More LessSummary: Protoplasts were formed from aged germlings and mycelia of Conidiobolus lamprauges, using a combination of chitinase and β-glucanase. Methanol, ethanol and propanol stimulated protoplast formation, apparently by a mechanism different from that of mercaptoethanol. Regeneration of protoplasts in soft agar was detectable by light microscopy 2 h after incubation and colonies were observable by the naked eye within 40 h; the regeneration rate was 65%.
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- Genetics And Molecular Biology
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Transfection of Corynebacterium lilium Protoplasts
More LessSummary: A protoplast transfection system has been developed for a lysine-producing bacterium, Corynebacterium lilium, using the DNA of phage CL31. Phage CL31 is lytic and specific to C. lilium and has a genome of approximately 48 kb. The transfection procedure involves a polyethylene-glycol-mediated introduction of the DNA into lysozyme-treated cells and has a maximum efficiency of 3 x 104 transfectants per μg DNA.
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Quantification of DNA Uptake by Dictyostelium discoideum Amoebae and the Stability of the DNA during Growth and Development
More LessSummary: We have developed a simple and accurate method to determine the amount of intact plasmid DNA taken up and retained by Dictyostelium discoideum amoebae during various transformation protocols. We have used this method to compare the efficiency of three different methods for introducing foreign DNA into D. discoideum amoebae. Both a calcium phosphate and a spheroplast fusion procedure gave good uptake, but no intracellular plasmid DNA was detectable after calcium chloride treatment. The exogenous DNA was rapidly lost after transformation but was 20-fold more stable during starvation rather than growth conditions, suggesting a possible approach to improving transformation efficiency. No transient expression of neomycin phosphotransferase activity of any of the heterologous animal or plant promoters used could be detected using a sensitive gel assay procedure.
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Discrimination by Heat and Proteinase Treatments between Flocculent Phenotypes Conferred on Saccharomyces cerevisiae by the Genes FLO1 and FLO5
More LessSummary: The effects of elevated temperature and of digestion with a variety of proteinases on the floc-forming ability of flocculent strains of Saccharomyces cerevisiae, both genetically defined (FLO1 and FLO5) laboratory and genetically undefined brewing strains, have been determined. This has permitted classification of the flocculent phenotypes of these strains according to criteria other than quantitative grading of flocculence. The flocculent phenotypes conferred by both the FLO1 and the FLO5 gene were irreversibly lost upon treatment with pronase, proteinase K, trypsin or 2-mercaptoethanol treatments. However, the floc-forming ability of cells of the FLO1 strain ABXL-1D was destroyed by chymotrypsin digestion and was stable to incubation at 70°C, whereas the floc-forming ability of cells of the FLO5 strain ABXR-11A was resistant to the action of chymotrypsin and was heat labile. Tetrad analysis of a cross of these FLO1 and FLO5 strains indicated that the chymotrypsin and heat sensitivity phenotypes were FLO-gene determined. It appears that expression of the FLO1 and FLO5 genes leads to the production of different and characteristic cell-wall proteins underlying their respective flocculent phenotypes.
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Relationship between DNA Content and Spore Volume in Sixteen Isolates of Verticillium lecanii and Two New Diploids of V. dahliae (= V. dahliae var. longisporum Stark)
More LessSummary: Sixteen wild-type isolates of Verticillium lecanii from different insects and non-insect hosts, soils and locations exhibited a wide range in spore volumes, from 2.18 μm3 to 18.25 μm3, as recorded by Coulter counter analysis. A cold hydrolysis technique for Feulgen DNA microdensitometry indicated that all the isolates were haploid. Two wild-type strains of V. dahliae, from rape and sugarbeet from Sweden, were shown to be stable diploids by the criteria of conidial volume and relative DNA content. After treatment with p-fluorophenylalanine, both V. dahliae strains produced haploid segregants with half the conidial volume and relative DNA content of the original parents. Both diploid strains are regarded as new records for V. dahliae var. longisporum (Stark).
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Complementation of Deletion and Insertion Mutants of TOL Plasmid pWW0: Regulatory Implications and Location of xylC Gene
More LessSummary: Two spontaneous mutant plasmids of TOL plasmid pWW0 are described. pWW0-660 contains an 18 kbp deletion of the entire xylCAB operon and pWW0-673 has a 3.4 kbp insert in the operator-promoter (OP1) region of xylCAB. In Pseudomonas putida hosts containing either plasmid, m-xylene was unable to act as a growth substrate or as an inducer of enzymes of the xylCAB or of the xylDLEGF operons. Complementation of these strains with a recombinant plasmid pWW0-3006 carrying the HindIII region D (HD) of pWW0 restored the Mxy+ phenotype and the ability of m-xylene to induce the xylDLEGF operon. The cloned HD region had no regulatory function but carried the OP1 region, the entire xylC structural gene and sufficient of xylA to support growth on m-xylene. XylC was more precisely located on a 1.9 kbp Sa/I subclone of the HD region. Comparison of the roles of m-xylene and m-methylbenzyl alcohol as inducers shows they are not equivalent and that whereas m-xylene can induce only xylCAB, m-methylbenzyl alcohol can induce both xylCAB and xylDLEGF. The restoration of the induction of xylDLEGF by m-xylene is due to the presence of xylA on the recombinant pWW0-3006, converting m-xylene to m-methylbenzyl alcohol.
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Nucleotide Sequence of the β-Lactamase Gene of Alkalophilic Bacillus sp. Strain 170
More LessSummary: A gene for the β-lactamase from alkalophilic Bacillus sp. strain 170 was cloned in a functional state on a 1-0 kb DNA fragment and its nucleotide sequence was determined. The coding sequence showed an open reading frame of 257 amino acids, which represents the β-lactamase precursor protein. It is considered that the signal peptide consisted of 30 amino acids including 12 hydrophobic amino acids.
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Damage to Chromosomal and Plasmid DNA by Toxic Oxygen Species
More LessSummary: Bacterial DNA was incubated with xanthine plus xanthine oxidase plus excess iron as an oxygen-species-generating system, and DNA injury was measured by agarose gel electrophoresis and by the ability of the DNA to transform competent bacteria. After 5 to 10 min incubation, the covalently closed circular form of plasmid DNA was converted into the open circular form, and after 30 min, to some extent into the linear form. Biological activity, measured as the number of transformed bacteria, decreased rapidly after 10 min incubation. Incubation of chromosomal DNA with the enzymic oxygen-species-generating system resulted in the degradation of DNA to small fragments within about 1 h. Excess iron was essential for the damaging effect of xanthine plus xanthine oxidase. Damage to DNA could be prevented by oxygen scavengers such as superoxide dismutase, catalase, mannitol and thiourea. Our results suggest that hydroxyl radical is the injurious oxidant for bacterial DNA, and that it can mediate physicochemical as well as biological alterations in DNA.
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Molecular Analysis of an Antibiotic Resistance Plasmid, pAV5, and Its Derivative Plasmids in Acinetobacter calcoaceticus
More LessSummary: The non-conjugative plasmid pAV5 specifies resistance to kanamycin/neomycin (KmR) and tetracycline (TcR). Physical evidence is presented to show that pAV5 gives rise to two plasmids, pAV51 (KmR) and pAV52 (TcR), which are formed by deletion of apparently non-overlapping segments of pAV5. Expression of TcR has been obtained in Escherichia coli and is associated with a 1.9 kb HindIII fragment found in pAV5 and in pAV52. Expression of KmR has been obtained in E. coli and is associated with a 1.3 kb PstI fragment found in pAV5 and pAV51. Evidence is presented that the KmR gene is flanked by inverted repeat sequences and is therefore tentatively identified as a transposon, designated Tn4411. The KmR gene specifies an aminoglycoside 3'-phosphotransferase-type I (APH(3')-I) enzyme.
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Bacteriophage D: an IncD Group Plasmid-specific Phage
More LessSummary: The existence of the plasmid incompatibility group D was reaffirmed as a result of compatibility experiments done on plasmids R687, R711b, R778b and R840 which were previously tentatively accepted as constituting the group. The group was further delineated by the isolation of a phage, phage D, which adsorbed specifically to IncD plasmid- encoded pili produced by Escherichia coli K12 strains and strains of Salmonella typhimurium, Proteus morganii and Klebsiella oxytoca harbouring one of these plasmids. Plaque formation, like that of phage pilHα, was temperature sensitive in that plaques formed at 26 °C but not at 37 °C. Plaques were fairly clear, regular in outline and varied from pinpoint to about 1.5 mm in diameter on E. coli hosts where plaques were detected, but on the other hosts the plaques were more turbid and often irregular in outline. The phage did not plate (or propagate) on IncD plasmid-carrying strains of Providencia alcalifaciens. Providencia stuartii or Serratia marcescens. The phage had an isometric hexagonal outline with a diameter of about 27 nm. It contained RNA and resembled two other RNA-containing phages, M and pilHα, by being sensitive to chloroform. It adsorbed to the sides of the very distal ends of the shafts of IncD plasmid-coded pili.
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- Pathogenicity And Medical Microbiology
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Influence of Cysteine Deprivation on Chlamydial Differentiation from Reproductive to Infective Life-cycle Forms
More LessSummary: The effects of omission of individual amino acids from growth medium on the differentiation of Chlamydia trachomatis DK-20 (serotype E) during infection of cycloheximide-treated McCoy cells are described. As judged by inclusion body staining with acridine orange, omission of cysteine from the medium severely retarded differentiation of reproductive reticulate body (RB) to infective elementary body (EB) forms. The effect appeared specific to cysteine in that omission of other amino acids had little or no effect on differentiation once RBs appeared. On restoration of cysteine, culture infectivity increased and inclusions contained organisms which, by cytochemical and morphological criteria, were differentiating to infective forms, indicating that cysteine deprivation did not irreversibly inhibit differentiation. Impairment of RB to EB differentiation in cysteine-less medium was also observed for three strains of Chlamydia psittaci and 10 other strains of C. trachomatis. It is suggested that the effect arises via the biosynthetic requirement for cysteine for provision of three cysteine-rich proteins, whose synthesis and insertion into the outer membrane have previously been shown to accompany RB to EB differentiation of C. psittaci 6BC and C. trachomatis 434 (serotype L2). Synthesis of cysteine-rich outer membrane proteins during differentiation may thus be common to all chlamydiae.
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- Physiology And Growth
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The Beneficial Effect of Hydrogenase in Azotobacter chroococcum Under Nitrogen-fixing, Carbon-limiting Conditions in Continuous and Batch Cultures
More LessSummary: The growth of three hydrogenase minus (Hup-) mutants of Azotobacter chroococcum was compared with that of the parent Hup+ strain in batch or continuous cultures. All three mutants gave similar yields to the parent under N2-fixing conditions at an optimum dilution rate (D) of 0.1 h−1 in sucrose-limited N2-fixing cultures. However, at higher D values the steady-state yields of sucrose-limited mutants were lower than those of the parent and washout occurred at lower D values. These observations were confirmed in carbon-limited mixed cultures where the parent strain outgrew the mutant at high D values. Such marked differences were not obtained in SO2- 4-or O2-limited continuous cultures. In batch culture at low sucrose levels the mutants displayed a long division lag compared with the parent, particularly with dilute inocula. Non-N2-fixing (NH+ 4-grown) conditions removed these differences. We suggest that one beneficial effect of hydrogenase is on the initiation of diazotrophic growth, particularly with restricted carbon/energy supply.
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Glycogen Accumulation and the Induction of Nitrogenase Activity in the Heterocyst-forming Cyanobacterium Anabaena variabilis
More LessSummary: Anabaena variabilis (ATCC 29413) grown in batch cultures for 2 d exhibited rapid glycogen synthesis upon dilution of the cell suspension. The cellular polysaccharide concentration attained a maximum after 9-12 h growth in fresh medium and decreased thereafter. The growth rate, the rate of glycogen accumulation and the maximum amount of glycogen increased when light intensity was increased. Accumulation occurred with both N2 and ammonia as N-sources. In cultures grown in the presence of ammonia, the increase in the cellular C-fraction upon dilution caused neither induction of nitrogenase nor heterocyst formation. However, ammonia depletion during subsequent growth gave rise to a second accumulation of glycogen followed by differentiation. Thus, in this phototroph, glycogen is synthesized without subsequent differentiation following an increase in average irradiation as long as the N-supply is maintained. Glycogen synthesis following N-depletion, however, is accompanied by induction of nitrogenase.
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Further Studies on the Subcellular Distribution of Cd2+ in Cd-sensitive and Cd-resistant Strains of Saccharomyces cerevisiae
More LessSummary: When a Cd-resistant strain (301 N) and a Cd-sensitive strain (101 N) of Saccharomyces cerevisiae were incubated in medium containing Cd2+, a large proportion of the cellular Cd2+ was found in the cytosol of strain 301 N, but not in that of strain 101 N. Approximately 65% of the cellular Cd2+ was released from strain 301 N after treatment with chitosan, which affects cell membrane permeability. About 80% of the cellular Cd2+ released from strain 301 N by chitosan treatment was detected in a 30000-10000 molecular weight fraction prepared by ultrafiltration. The distribution of Cd2+ into the cytosol in strain 301 N was inhibited in the presence of cycloheximide. The proportion of cellular Cu2+ or Zn2+ present in the cytosol after incubation with these ions was similar for the two strains (about 40%).
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Cyclic AMP and the Stimulation of Trehalase Activity in the Yeast Saccharomyces cerevisiae by Carbon Sources, Nitrogen Sources and Inhibitors of Protein Synthesis
More LessSummary: Addition of glucose to acetate-grown cells of Saccharomyces cerevisiae caused a rapid transient increase in the cAMP level followed by a 10-fold, transient increase in the activity of trehalase. Exhibition bromide and acridine analogues inhibited both glucose-induced responses in a similar way, confirming the role of the cAMP signal as the second messenger in the sugar-induced activation of trehalase. When nitrogen sources or protein synthesis inhibitors were added after the transient glucose-induced increase in the trehalase activity, a rapid reactivation of trehalase occurred. In this case, however, there was only a very small increase in the cAMP level, which appeared to be insignificant. When the nitrogen source or the protein synthesis inhibitor was added together with glucose, the trehalase activity remained high for a much longer time also without a significant effect on the cAMP level. When a membrane depolarizing agent was added together with the glucose, both the trehalase activity and the cAMP level remained high. Reversibility experiments in which trehalase was activated to different degrees also showed that for high sugar-induced trehalase activation a high cAMP level is needed, while nitrogen sources stimulate trehalase activity without affecting cAMP levels. In cell extracts, both cAMP and cGMP were able to activate trehalase, the latter however only at 10-fold higher concentrations. The cGMP level in vivo was about 10-fold lower than the cAMP level and was not significantly affected by nitrogen sources or protein synthesis inhibitors. Hence, neither cAMP nor cGMP seem to be involved as the second messenger in the stimulating effect of nitrogen sources and protein synthesis inhibitors on trehalase activity in yeast. Since all other evidence obtained here and before strongly points to regulation of trehalase by a ‘cAMP-dependent’ protein kinase, we suggest that the presence of a nitrogen source in the growth medium of yeast induces the rapid synthesis of an alternative second messenger able to activate this or another protein kinase.
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Inhibition of the Expression of Cell-associated Fructosyltransferase in Streptococcus salivarius by Octyl β-D-Glucopyranoside
More LessSummary: Octyl β-D-glucopyranoside prevented the expression of cell-associated fructosyltransferase activity in Streptococcus salivarius ATCC 25975 grown in batch culture or incubated in non-proliferating cell suspension medium. This effect was not due to the direct inhibition of enzyme activity nor due to the loss of active enzyme into the external medium. The prevention of enzyme expression did not appear to be due to the inhibition of a general translocation mechanism for protein secretion, since fructosyltransferase activity was not detected within the cytoplasm of lysed cells grown in the presence of octyl β-D-glucopyranoside; nor was there any observed inhibition of the secretion of the extracellular enzyme glucosyltransferase. These and other observations supported the view that fructosyltransferase was not secreted across the cytoplasmic membrane in an active form before becoming associated with the cell surface.
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Fosfomycin Causes Transient Lysis in Escherichia coli Strains Carrying Fosfomycin-resistance Plasmids
More LessSummary: Escherichia coli cells carrying fosfomycin-resistance plasmids show high levels of resistance towards this drug. However, the plasmid-carrying strains exhibited a transient lytic phase induced by fosfomycin when grown in rich liquid media. This lytic phase was not observed if the cells were grown in liquid minimal media. Fosfomycin-induced lysis depended on the accumulation of drug inside the bacteria, presumably as a result of the saturation of the fosfomycin modification system. Growth recovery after lysis was not due to drug inactivation in the culture medium and could be explained by selection of mutants showing impaired fosfomycin transport when high concentrations of fosfomycin were used. However, there was no selection of mutants with low drug concentrations.
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Influence of Amino Acids on Growth and Cell Wall Composition of Methanobacteriales
More LessSummary: Methanogenic bacteria with pseudomurein sacculi incubated with elevated concentrations of amino acids showed growth inhibition, changes in morphology and, under certain conditions, lysis. Methanobacterium thermoautotrophicum incorporated the amino acids glycine, threonine, ornithine and, in small amounts, aspartic acid into the sacculi, but not D-alanine, meso-diaminopimelic acid or the amino sugar galactosamine.
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Ethanol-induced Germ Tube Formation in Candida albicans
More LessSummary: Ethanol is the first reported compound which can induce germ tube formation in Candida albicans without the addition of any nitrogen-containing nutrients. Conditions controlling induction of germ tubes in C. albicans by ethanol were investigated. Ethanol (17.1 mM) in buffered salts solution containing sodium bicarbonate induced 70 to 80% of yeast phase cells of C. albicans to form germ tubes. Germ tubes could be induced by ethanol (0.08 to 340 mM) at temperatures ranging from 29 to 41 °C (optimum 37 °C) and at pH values ranging from 3.0 to 8.0 (optimum 5.75). The germ tubes averaged 11 μm in length after 6 h at 37 °C. The percentage of cells forming germ tubes decreased as the concentration of cells in the induction solution was increased above 4 x 105 cells ml−1. Germ tubes first appeared 45 to 60 min after continuous exposure to ethanol at 37 °C and all cells which formed germ tubes did so by 2 h. Germ tube length decreased as the pH was increased but was independent of the concentration of ethanol. Oxygen was required for germ tube formation. In addition to ethanol, 1-propanol, 2-propanol, 1-butanol and acetic acid could induce germ tube formation, whereas methanol could not. These results indicate that the cells must mobilize their endogenous nitrogen and probably carbohydrate reserves in order to initiate formation of germ tubes. The evidence is inconclusive as to whether ethanol itself must be metabolized for germ tube induction to occur, although it is not thought to act by a nonspecific interaction with the cell membrane.
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- Systematics
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Polar Lipids in Methanogen Taxonomy
More LessSummary: Polar lipid patterns of representative methanogens were recorded by two-dimensional thin-layer chromatography. Phenotypically similar Methanobacterium spp., Methanobrevibacter spp. and Methanomicrobium spp. could readily be distinguished from each other. Similarly, Methanogenium spp. and phenotypically similar Methanococcus spp. had different polar lipid patterns. Single examples from the monospecific genera Methanospirillum, Methanoplanus and Methanothermus had distinctive polar lipid patterns, but Methanolobus tindarius had a similar pattern to Methanosarcina spp. The isopranoid ether lipid cores from the polar lipids were identical for those species within any one genus. Novel core lipids were identified in examples from the genera Methanomicrobium, Methanosarcina and Methanolobus.
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Comparative Electrophoretic Profiles of Esterases, and of Glutamate, Lactate and Malate Dehydrogenases, from Aeromonas hydrophila, A. caviae and A. sobria
B. Picard and Ph. GoulletSummary: Esterases, and glutamate, lactate and malate dehydrogenases of 64 Aeromonas hydrophila, A. caviae and A. sobria strains, were analysed by polyacrylamide agarose gel electrophoresis and by thin layer isoelectrofocusing. On the basis of the isoelectric points of malate dehydrogenase from the three species and the mobility of lactate dehydrogenase from A. sobria, 8 species specific zymotypes were defined: three for A. hydrophila strains, three for A. caviae strains and two for A. sobria strains. These zymotypes correlated with previously established DNA hybridization groups. The other electrophoretic data were found to be less useful for distinction between A. hydrophila and A. sobria strains, but supported differentiation into zymotypes for A. caviae strains. The two-dimensional electrophoretic profile established by plotting isoelectric point against electrophoretic mobility of the major esterase illustrated the degree of enzyme polymorphism among the strains of the three species. Variation in electrophoretic patterns within A. hydrophila and A. caviae might provide useful epidemiological markers.
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- Short Communications
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A Rapid Method to Differentiate between Four Species of the Endomycetaceae
More LessSummary: The cellular long-chain fatty acids of seven strains representing four species of the Endomycetaceae were extracted from yeast cells by saponification and analysed as their methyl esters by GLC. Each of these species produced a distinctive mean fatty acid ‘fingerprint'. It was possible to distinguish between the four species within 4 h after they were obtained from 48 h cultures as compared with 7 to 10 d for more conventional methods.
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The Peptidoglycan of Neisseria gonorrhoeae, With or Without O-Acetyl Groups, Contains Anhydro-muramyl Residues
More LessSummary: Muramidase digests of alkali-treated SDS-insoluble peptidoglycan from two strains of Neisseria gonorrhoeae were examined. Both strains contained disaccharide peptide monomers that had intramolecular 1,6-anhydro-muramyl ends. In contrast to strain 1L260, in which 50% of the monomer fraction is O-acetylated, the monomer fraction from strain RD5 was completely devoid of O-acetyl groups, as shown by HPLC. Penicillin decreased the O-acetylation of peptidoglycan but did not affect the proportion of anhydro-muramyl residues.
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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)