- Volume 135, Issue 1, 1989
Volume 135, Issue 1, 1989
- Biochemistry
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Respiration in the Cysts and Trophozoites of Giardia muris
More LessCysts and trophozoites of the parasitic protozoon Giardia muris both showed respiratory activity but respiration in cysts was only 10 to 20% that of trophozoites. The O2 dependence of respiration in cysts and trophozoites showed O2 maxima above which respiration decreased. The O2 concentration at which the respiration rate was greatest was higher for cysts than trophozoites. The effects of various inhibitors on cyst and trophozoite respiration suggested that flavoproteins and quinones play some role in respiration. The substrate specificities and the effects of inhibitors on G. muris trophozoites were similar to those observed for Giardia lamblia. Metronidazole, the drug most commonly used in the treatment of giardiasis completely inhibited respiration and motility in trophozoites; however, it had no effect on either respiration or viability in cysts. Menadione, a redox cycling naphthoquinone, stimulated then completely inhibited respiration in cysts and trophozoites; a complete loss of cyst viability or trophozoite motility was also observed. The effects of menadione on G. muris may indicate that redox cycling compounds have potential as chemotherapeutic agents for the treatment of giardiasis.
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Purification and Characterization of the 2-Oxoglutarate Dehydrogenase Complex from Dictyostelium discoideum
The 2-oxoglutarate dehydrogenase complex was isolated from the cellular slime mould, Dictyostelium discoideum, and purified 113-fold. The enzyme exhibited Michaelis-Menten kinetics and the K m values for 2-oxoglutarate, CoA, and NAD were 10 mm, 0002 mm, and 007 mm, respectively. The K i value for succinyl-CoA was determined to be 0004 mm and the K i for NADH was 0018 mm. AMP had positive effects whereas ATP had negative effects on the enzyme activity. The kinetic constants determined in this study and the reaction mechanism suggested can now be incorporated into a transition model of the tricarboxylic acid cycle during differentiation of D. discoideum.
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Composition of Lipopolysaccharides from Alteromonas putrefaciens (Shewanella putrefaciens)
More LessLipopolysaccharides from eight strains of Alteromonas putrefaciens (Shewanella putrefaciens) representing four groups defined by DNA-DNA homology studies have been compared. All products were of the R-type, lacking a polymeric side chain. In each case lipid A was based on glucosamine and contained a complex range of fatty acids. In general, the major non-hydroxy acids were 11-methyldodecanoic acid and tridecanoic acid, and the major hydroxy acids were 3-hydroxyundecanoic acid, 3-hydroxydodecanoic acid, 3-hydroxy-11-methyldodecanoic acid, 3-hydroxytridecanoic acid and 3-hydroxytetradecanoic acid. All lipopolysaccharides contained a 3-deoxy-2-octulosonic acid, only detectable after dephosphorylation. All core oligosaccharides contained d-galactose and d-glycero-d-manno-heptose, and all except those of group I strains also contained d-galactosamine. Group I strains (including NCIB 10471, the type strain) were distinguished from others by the presence in the core of 3-amino-3,6-dideoxyglucose, d-glucose, and acid-stable phosphate residues. Quinovosamine and d-fructose were found only in group IV strains. Core oligosaccharides from the group II and group III strains, as isolated, were deficient in heptose and seemed to have the same structure. During mild acid hydrolysis of the lipopolysaccharides, various monosaccharides and phosphates were released. The monosaccharides were d-galactose (group I), d-fructose (group IV), and d-galacturonic acid (mainly groups II and III). Phosphates identified were ethanolamine pyrophosphate, ethanolamine phosphate, pyrophosphate, and orthophosphate. The chemotaxonomic implications of the results are discussed.
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- Biotechnology
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Translational Fusions with Fragments of the trpE Gene Improve the Expression of a Poorly Expressed Heterologous Gene in Escherichia coli
More LessA series of plasmids expressing fusions between the trpE gene product, anthranilate synthase component I and the major immunogen (VP1) of foot and mouth disease virus were constructed such that increasing amounts of the 3′ end of trpE were deleted. Deletions removing up to 70% of trpE had little effect on the quantity of fusion protein expressed, while the number of molecules appeared to increase. Larger deletions led to a steady decrease in both the quantity of fusion protein produced and in the number of molecules. This is consistent with trpE being responsible for the high levels of expression of VP1 by its gene product stabilizing VP1 against proteolytic degradation. Some out-of-frame deletion mutants were also produced. All deletion mutants in one wrong reading frame expressed low levels of two VP1-containing polypeptides. This observation is interpreted as being due to re-initiation of translation at a site inside the VP1 sequence which is activated by local termination of translation.
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- Development And Structure
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Detection of Surface-exposed Epitopes on Chlamydia trachomatis by Immune Electron Microscopy
More LessThe cell surfaces of two Chlamydia trachomatis serovars were explored by immune electron microscopy with monoclonal antibodies that recognize a number of chlamydial outer-membrane components. Species, subspecies and serovar-reactive epitopes on the major outer-membrane protein (MOMP) of a lymphogranuloma venereum biovar strain, L2/434/Bu, and a trachoma biovar strain, F/UW-6/Cx, were exposed on the surfaces of both elementary bodies (EBs) and reticulate bodies (RBs). Three epitopes on MOMP were inaccessible on EBs and RBs of both strains. These included a genus-reactive, species-reactive, and a subspecies-reactive epitope. In contrast, genus-specific epitopes on lipopolysaccharide (LPS) were not detected on the EB surface, but were clearly expressed on RBs of both L2/434/Bu and F/UW-6/Cx chlamydiae. Antibodies specific for the 60 kDa and 12 kDa cysteine-rich outer-membrane proteins did not react with surface epitopes on either EBs or RBs. These data provide evidence that MOMP is a major surface antigen of both morphological forms, whereas some portions of the LPS molecule are exposed on the RB surface but become inaccessible to antibody after conversion to the infectious EB form.
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- Ecology
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Determination of the Substrates for Sulphate-reducing Bacteria within Marine and Esturaine Sediments with Different Rates of Sulphate Reduction
More LessThe substrates used by sulphate-reducing bacteria in sediment slurries from Loch Eil, Loch Etive and the Tay estuary were determined by selectively inhibiting sulphate reduction with 20 mm-molybdate and measuring the resultant substrate accumulation. Substrate accumulation was linear after molybdate addition, and the rate of accumulation closely matched sulphate reduction rates, indicating that metabolic pathways other than those specifically involving sulphate reduction were not affected by the inhibitor. In sediments from all three sites acetate was a major substrate, although the percentage of sulphate reduced due to acetate oxidation varied considerably among the sites (Tay estuary, 35%; Loch Eil, 64%; Loch Etive, 100%). In addition to acctate, 17 individual substrates were shown to be involved in sulphate reduction to varying extents in the Tay estuary and Loch Eil sediments; these included lactate, H2, propionate, iso- and n-butyrate, iso- and n-valerate, 2-methylbutyrate and amino acids. At both sites propionate accounted for between 6 and 12% of sulphate reduction. Butyrate (n- and iso-), iso-valerate and 2-methylbutyrate were of approximately equal importance at each site and together accounted for 13 and 11%, respectively, of the sulphate reduction in the Tay estuary and Loch Eil sediments. Lactate was only importnat in the Tay estuary sediments, where it accounted for 43% of sulphate reduction. The rate of accumulation of amino acids was greatest in the Tay estuary sediments, but the contribution of amino acids to sulphate reduction was higher in the Loch Eil (9%) than in the Tay estuary sediments (2%). Of the 21 individual amino acids that were measured there was a linear increase in nine; the most important of these were serine, glutamate and arginine. In general, when sulphate reduction rates were high the substrates for this process were more varied than when rates were low. Combining the results of two experiments and assuming complete degradation of the individual substrates, almost all the sulphate reduction could be accounted for at each site (Tay estuary, 101%; Loch Eil, 98%; Loch Etive, > 100%).
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- Genetics And Molecular Biology
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Physical and Biochemical Characterization of the qacA Gene Encoding Antiseptic and Disinfectant Resistance in Staphylococcus aureus
More LessWe have previously cloned a 3·5 kb fragment from the Staphylococcus aureus multiresistance plasmid pSK1 which carries the qacA determinant responsible for linked resistance to acriflavine (Acr), ethidium bromide (Ebr), quaternary ammonium compounds (Qar), propamidinc isethionate (Pir), and diamidinodiphenylamine dihydrochloride (Ddr). This report presents a biochemical and physical analysis of qacA and shows the widespread carriage of this gene on S. aureus resistance plasmids. Tn5 insertion mutagenesis defined the extent of qacA to within 2·40 kb of pSK1 DNA. Examination of the expression of insertion and deletion mutants of the cloned qacA sequences in both maxicells and minicells led to the association of a 50 kDa protein, designated QacA, with the Acr Ebr Qar Pir Ddr phenotype. Based on fluorimetric and isotopic assays used to determine the extent of accumulation of ethidium bromide by S. aureus strains harbouring pSK1, we propose that the basis of Acr Ebr Qar Pir Ddr in S. aureus is a qacA-mediated efflux system.
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Products of Defective Lysogeny in Serratia marcescens SMG 38 and Their Activity against Escherichia coli and Other Enterobacteria
More LessFrom a series of Serratia marcescens clinical isolates analysed with respect to bacteriocin production, one strain (SMG 38) was exceptional in that it produced two distinct phage-tail-like bacteriocins differing in morphology, sedimentation, heat sensitivity, and host range. The more active component (bc25) was effective against Serratia, while the other component (McG) inhibited growth of Escherichia coli, Salmonella typhimurium and Shigella sonnei, but not Serratia. Plaque formation on tested strains was negative except in the single case of the lysate of a subclone of SMG 38 which caused the production of a virulent phage, ϕε, in E. coli K12 RH 5108. This seems to be a rare event. Like the bacteriocin McG, phage ϕε used the same receptor protein, coded at about 30 min (locus fig) on the E. coli chromosome, as does the temperate and serologically unrelated phage ϕγ. Both McG and UV-irradiated ϕε killed sensitive bacteria. The survival rate depended on the input multiplicity and also on the indicator strain, and was increased by the presence of prophage ϕ80 in the cell. When survivors were allowed to resume their growth under normal conditions, they showed cell elongation whatever their RecA phenotype. No difference was observed between the two agents with respect to these observations, except that McG, unlike irradiated ϕε, was inactive against Klebsiella pneumoniae UNF 5023, which possessed the Fig receptor.
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Cloning and Nucleotide Sequence of the Isoamylase Gene from a Strain of Pseudomonas sp
More LessA strain of PseudomonasY sp., SMP1, isolated from a soil sample collected in the Monterotondo area (Rome), secreted isoamylase activity into the culture medium. The enzyme was purified and optimal reaction and stability conditions were determined by varying pH and temperature. The chemico-physical properties of the enzyme were similar to those of the isoamylase purified in Japan more than 20 years ago from ‘Pseudomonas amyloderamosa’ strain SB15. A genomic library of SMP1 was prepared in Escherichia coli using pUC12 as vector. Two isoamylase-producing colonies were identified out of 6300 screened. The hybrid plasmids isolated from the two clones showed common restriction patterns. The chromosomal portion of one of these plasmids (pSM257) was completely sequenced. Comparison between the deduced amino acid sequence of the isoamylase and the published sequences of other amylolytic enzymes showed the presence of conserved domains.
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Symbiotic Plasmid Rearrangement in a Hyper-recombinant Mutant of Rhizobium leguminosarum biovar phaseoli
More LessThe symbiotic plasmid of Rhizobium leguminosarum biovar phaseoli strain CFN23 has been previously shown to undergo a series of genetic rearrangements that modify the bacterial symbiotic phenotype. A hyper-recombinant derivative of strain CFN23 was isolated. This derivative (strain CFN2300) has a similar phenotype to that reported for Escherichia coli mutants defective in DNA metabolism. The frequency of CFN23 symbiotic plasmid deletion is increased in the CFN2300 background, suggesting that homologous genetic recombination is involved in the generation of this genetic rearrangement.
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Cloning and Characterization of Overlapping DNA Fragments of the Toxin A Gene of Clostridium difficile
More LessClostridium difficile, a human pathogen, produces two very large protein toxins, A and B (250–600 kDa), which resist dissociation into subunits. To clone the toxin A gene, a genomic library of 3–8 kb chromosomal DNA fragments of C. difficile strain VPI 10463 established in pUC12 was screened with a rabbit polyclonal toxin A antiserum. Thirty-five clones were isolated which carried 2·5–7·0 kb inserts representing a 10 kb region of the C. difficile genome. All the inserts were oriented in the same direction, suggesting that toxin A gene expression was under control of the lac promoter of the pUC12 vector. Western blot experiments revealed the presence of low amounts of fusion proteins of variable size (30–170 kDa) in Escherichia coli strains harbouring recombinant plasmids. As deduced from subcloning experiments, the DNA sequences encoding toxin A comprised about 4 kb, corresponding to about 140 kDa of the 300–600 kDa protein. This was either due to incomplete cloning of the gene or it might indicate a subunit composition of toxin A. No additional gene(s) with homology to the cloned toxin A gene was detected.
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- Pathogenicity And Medical Microbiology
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Electrophoretic Karyotype of the Pathogenic Yeast Cryptococcus neoformans
More LessThe electrokaryotype of the pathogenic yeast Cryptococcus neoformans is described for the first time. Three different patterns were seen: (a) serotypes B and C (variety gattii) are similar and consist of nine chromosome mobility groups of >580 kb; (b) serotype A (variety neoformans) revealed eight chromosome-like groups > 700 kb; (c) serotype D (the second serotype of variety neoformans) not only differs from those described above, but each D isolate tested showed a different distribution of bands. The discrepancy, and the importance of electrokaryotyping as a taxonomic tool, are discussed.
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An Immunoprotective Monoclonal Antibody Directed against Leptospira interrogans serovar copenhageni
A monoclonal antibody (mAb) was prepared by hybridoma technology in BALB/c mice immunized to Leptospira interrogans serovar copenhageni. This mAb agglutinated serovars copenhageni and icterohaemorrhagiae to high titres and protected hamsters, dogs and monkeys against challenge with a virulent strain of serovar copenhageni. The mAb gave protection to hamsters at dilutions up to 1 in 1000; at a 1 in 10 dilution the protective effect lasted for at least two weeks. Biochemical analysis by SDS-PAGE and Western blotting indicated that this mAb reacred with an epitope of a carbohydrate nature.
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The Persistence of Chlamydia trachomatis Elementary Body Cell Walls in Human Polymorphonuclear Leucocytes and Induction of a Chemiluminescent Response
More LessHuman polymorphonuclear leucocytes (HPMN) were incubated with [35S]methionine-labelled Chlamydia trachomatis (serovar L2/434/Bu) elementary bodies (EB) and EB cell walls. No net loss in the TCA-precipitable radioactivity was observed over 24 h in the HPMN that had taken up EB cell walls. SDS-polyacrylamide gel electrophoresis of the labelled C. trachomatis EB and EB cell wall proteins extracted from the HPMN at 2 and 24 h after infection demonstrated the persistence of most of the chlamydial cell wall polypeptides. Analysis of extracts of the HPMN that had taken up either EB or EB cell walls on Urografin density gradients at 2 and 24 h after infection, and electron microscopic observations on fractions representing the peaks, demonstrated the persistence of the EB cell walls in the HPMN. Electron microscopic observations of HPMN that had taken up EB or EB cell walls demonstrated EB cell walls in the HPMN phagosomes at 24 h after infection. The HPMN exposed to EB and EB cell walls of C. trachomatis gave chemiluminescent (CL) responses with peaks respectively 12 and 7 times greater than the peak value of the control. The significance of the persistence of the EB cell wall polypeptides and cell walls in the HPMN and activation of the HPMN to produce oxygen radicals (i.e. a CL response), and its possible relation to rheumatic diseases, is discussed.
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Effect of Chlamydia trachomatis Infection on Ciliary Activity in Single Cells from Cultures of Human Nasal Polyps
More LessWe have tested the hypothesis that the ciliary activity of epithelial cells from human nasal polyps is altered after infection with Chlamydia trachomatis. Ciliated epithelial cells from human nasal polyps were cultured and infected with C. trachomatis. The measurement of ciliary beating was based on a technique which enables one to monitor a fraction of a single ciliated cell. A marked decrease of ciliary beating frequency versus time was observed 24 h after infection with C. trachomatis. About 50% of the cilia of infected cells were paralysed 48 h post-infection. The potential effect of C. trachomatis infection on the physiological functions dependent on cilia is discussed.
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Expression and Detection of Different Biotype-associated Cell-bound Haemagglutinins of Vibrio cholerae O1
More LessThe expression of two cell-bound haemagglutinins, one sensitive to l-fucose (FSHA) and the other to d-mannose (MSHA), on Vibrio cholerae O1 strains of both the classical and the El Tor biotypes was studied by (i) agglutination of chicken and human group O erythrocytes in the presence of l-fucose or d-mannose, (ii) binding of the bacteria to l-fucose- and d-mannose-coated agarose beads, and (iii) agglutination of the bacteria by ‘biotype-specific’ antisera. All of the 12 classical strains studied that were isolated before 1979 gave FSHA of human O erythrocytes whereas only 6 of 17 classical strains isolated during recent epidemics expressed FSHA; a few of the classical strains expressed MSHA in addition to FSHA. All the El Tor strains gave MSHA of chicken erythrocytes and one strain also expressed FSHA. Both the cell-bound HAs were optimally expressed during the exponential phase of growth; FSHA markedly decreased during the late exponential phase while the MSHA usually persisted into the stationary phase. The expression of FSHA and MSHA correlated very well with the direct binding of vibrios to fucose- and mannose-coated agarose beads, respectively. Antiserum ‘specific’ for classical vibrios agglutinated classical strains expressing FSHA and also the El Tor strain exhibiting FSHA. Similarly, the anti-El Tor serum agglutinated all El Tor strains and also classical strains expressing MSHA, suggesting that the ‘biotype-specific’ sera were specific for the biotype-associated cell-bound HAs.
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- Physiology And Growth
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Effect of Zinc Deficiency on the Appearance of Two Immunodominant Protein Antigens (32 kDa and 65 kDa) in Culture Filtrates of Mycobacteria
More LessAfter growth of six strains of mycobacteria on Sauton medium in the absence of added Zn2+, cell yields were lowered, to between 22% and 67% of the yields obtained when Zn2+ (5 μM) was added. Two immunodominant proteins, named P64 and P32 (antigens of 62-65 kDa and 29-33 kDa, respectively) were abundant in culture filtrates after growth of mycobacteria. P64 was present at elevated concentrations (showing a 9- to 16-fold increase as a percentage of the total protein released) after Zn2+-deficient growth of five of the six strains studied; in Mycobacterium tuberculosis it represented 25% of all released proteins. However, little P64 was detected in culture filtrates of M. fortuitum and of M. phlei grown under Zn2+ deficiency, and in the latter there was no increase of P64 during Zn2+ deficiency.
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Simultaneous Assimilation and Denitrification of Nitrate by Bradyrhizobium japonicum
More LessBradyrhizobium japonicum strain CB 1809 assimilated and denitrified 15NO− 3 simultaneously to 15NH+ 4 and 15N2, respectively, when incubated under anaerobiosis. Washed cells from cultures grown in air in the presence of 5 mM-nitrate, assimilated 70% of the 15NO− 3 into cell-nitrogen but only after a lag of 10 h during which time NO− 2 accumulated. In washed cells grown at 2% (v/v) O2 with 5 mm-nitrate, 15NO− 3 was denitrified to 15N2 (95%) in 1–2 h. The low O2 tension in the culture medium resulted in increased activity of nitrate and nitrite reductases in the cells. When 10 mm-glutamate was included with 5 mm-nitrate at 2% (v/v) O2, washed cells from these cultures had less nitrate and nitrite reductase activities and when 15NO− 3 was supplied to these cells there was a transient accumulation of NO− 2 (1 h) prior to maximum denitrification. Washed cells prepared from cultures grown at 2% (v/v) O2 with glutamate alone utilized 15NO− 3, only after a lag period of 20-40 h, assimilation by (60%) and denitrification (40%).
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Regulation of Glucose Transport in Candida utilis
More LessThe transport systems for glucose present in Candida utilis cells, growing in batch and continuous cultures on several carbon sources, have been studied. Two different systems were found: a proton symport and a facilitated diffusion system. The high-affinity symport (K m for glucose about 15 m) transported one proton per mole of glucose and was partially constitutive, appearing in cells grown on gluconeogenic substrates such as lactate, ethanol and glycerol. It was also induced by glucose concentrations up to 07 mm and repressed by higher ones. The level of repression depended on the external glucose concentration at which cells had grown in a way similar to that shown by the maltose-uptake system, so both systems seem to be under a common glucose control. Initial uptake by facilitated diffusion, the only transport system present in cells growing at glucose concentrations higher than 10 mm, showed a complex kinetic dependence on the extracellular glucose concentration. This could be explained either by the presence of at least two different systems simultaneously active, one with a K m around 2 mm and the other with a K m of about 1 m, or by the allosteric or hysteretic behaviour of a single carrier whose apparent K m would oscillate between 2 and 70 mm.
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Isolation and Characterization of Mutants of Saccharomyces cerevisiae Able to Sporulate in the Presence of Glucose
More LessMutants of Saccharomyces cerevisiae able to sporulate in the presence of 1% (w/v) glucose have been isolated. A single mutation, srg1, is responsible for this phenotype. One of the srg1 mutants, A-20, was characterized biochemically. The mutants had generation times similar to that of the parental strain when growing with glucose or ethanol as carbon source, and on sporulation medium in the absence of glucose they behaved like the wild-type. In contrast, in the presence of glucose, mutant A-20 raised the pH of the medium and degraded glycogen after an initial period of accumulation. This behaviour was not observed in the wild-type. cAMP concentration increased in the mutant after addition of glucose, although to a lesser extent than in the parent. A marked difference between the mutant and the wild-type was the slow utilization of glucose by the mutant when placed in sporulation medium. In addition, in sporulation medium, the glucose uptake system was inactivated with different kinetics in the mutant compared with the wild-type. The srg1 mutation seems therefore to affect the glucose uptake system.
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Purification and Some Properties of Two Forms of Chitinase from Mycelial Cells of Mucor rouxii
More LessChitinase activity was measured in extracts of mycelial cells of Mucor rouxii as a function of the culture age. There was a peak of specific activity at the mid-exponential phase of growth (10 h), which paralleled chitin synthase activity. An additional peak of chitinase with higher specific activity was detected in 4 h cultures, which coincided with the onset of germination. Purification of chitinase activities from the cytoplasm revealed two enzymes, I and II, with different molecular mass and ionic charge. Antibodies induced with chitinase I did not cross-react with chitnase II. Both enzymes digested nascent chitin preferentially over preformed chitin, yielding diacetylchitobiose as the sole product of hydrolysis.
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- Systematics
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New Probability Matrices for Identification of Streptomyces
More LessThe character state data obtained for clusters defined in a previous phenetic classification were used to construct two probabilistic matrices for Streptomyces species. These superseded an original published identification matrix by exclusion of other genera and the inclusion of more Streptomyces species. Separate matrices were constructed for major and minor clusters. The minimum number of diagnostic characters for each matrix was selected by computer programs for determination of character separation indices (charsep) and a selection of group diagnostic properties (diachar). The resulting matrices consisted of 26 phena × 50 characters (major clusters) and 28 phena × 39 characters (minor clusters). Cluster overlap (overmat program) was small in both matrices. Identification scores were used to evaluate both matrices. The theoretically best scores for the most typical example of each cluster (mosttyp program) were all satisfactory. Input of test data for randomly selected cluster representatives resulted in correct identification with high scores. The major cluster matrix was shown to be practically sound by its application to 35 unknown soil isolates, 77% of which were clearly identified. The minor cluster matrix provides tentative probabilistic identifications as the small number of strains in each cluster reduces its ability to withstand test variation. A diagnostic table for single-membered clusters, constructed using the charsep and diachar programs, was also produced.
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Comparative Electrophoretic Polymorphism of Esterases and Other Enzymes in Escherichia coli
Ph Goullet and B. PicardThe electrophoretic polymorphism of esterases was compared with that of other enzymes in Escherichia coli populations by investigating allozyme distribution of four esterases (A, B, C and I) within both the subspecific groups I, II and III and the new groups A, B1, B2, C, D and E, which have been distinguished by electrophoretic analysis of 11 and 35 enzymes respectively in the 72 reference strains of the ECOR collection. Electrophoretic distribution of esterases was distinct for each of the three subspecific groups as indicated by distributions of allozymes and electrophoretic types (distinctive combination of allozyme for the four esterases). Esterase polymorphisms of the three subspecific groups appeared to have similar features to those of three previously studied natural populations of strains obtained from human and animal gastrointestinal tracts and extra-intestinal infections in humans. Multiple correspondence analyses using data obtained from the four esterases and the 11 other enzymes also distinguished the groups A, B1, B2, C, D and E. All strains of group B2 showed the B2 electrophoretic pattern of esterase B, which appeared to be a marker of a distinct cluster of strains frequently implicated in extra-intestinal infections.
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- Corrigendum
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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)