- Volume 129, Issue 5, 1983
Volume 129, Issue 5, 1983
- Obituary
-
- Sgm Special Lecture
-
- Biochemistry
-
-
-
The Dehalogenases of a 2,2-Dichloropropionate-degrading Bacterium
More LessA bacterium capable of utilizing the selective herbicide 2,2-dichloropropionate (2,2DCP; Dalapon) as sole source of carbon and energy was shown to possess inducible dehalogenase activity. Enzyme activity was also induced by numerous other haloalkanoic acids. Chlorinated compounds were generally better inducers of dehalogenase than the corresponding brominated compounds. Cell extracts of 2,2DCP-grown bacteria liberated free halide ion from several C-2 substituted alkanoic acids; C-3 and C-4 monosubstituted acids and halogenated acetamides were not attacked. Brominated compounds were dehalogenated more readily than the corresponding chlorinated compounds. Gel electrophoresis of cell extracts indicated the presence of at least two dehalogenases in 2,2DCP-grown bacteria. These were separable by ion-exchange chromatography. Both partially purified dehalogenase activities had a fairly broad specificity, attacking several haloalkanoic acids in addition to 2,2DCP. Monohalogenated acetates were substrates for one of the dehalogenase activities but were potent inhibitors of the other. The two activities differed in their susceptibility to thiol-blocking reagents but had similar apparent molecular weights.
-
-
-
-
The 650 nm Chromophore in Escherichia coli is an ‘Oxy-’ or Oxygenated Compound, Not the Oxidized Form of Cytochrome Oxidase d: An Hypothesis
More LessThe form of cytochrome d in Escherichia coli and Azotobacter vinelandii that shows an absorption maximum at 648 to 652 nm (cytochrome d 650) is generally regarded as the oxidized form of this terminal oxidase. Membranes from E. coli grown under oxygen-limited conditions, when treated with ferricyanide, do not reveal cytochrome d 650, whereas a sharp symmetrical band at 652 nm results from the reaction of the reduced enzyme with O2 at either room temperature or after flash photolysis of the CO-liganded form at 130 C. Electron paramagnetic resonance spectroscopy of cytochrome d 650 trapped at 130 C shows that its spectrum is indistinguishable from the CO-liganded form and does not reveal resonances of high spin ferric haem previously attributed to cytochrome d. An hypothesis is proposed in which cytochrome d 650 is an early intermediate in the reaction of reduced cytochrome d with oxygen and is not the fully-oxidized (ferric) species. An analogy between cytochrome d 650 and oxyhaemoglobin is presented and the hypothesis discussed in relation to earlier work, in which the indirect interconversions of reduced cytochrome d and d 650 have been explained by proposing the existence of an invisible form. It is suggested that this form could be the oxidized enzyme.
-
-
-
The Reaction with Oxygen of Cytochrome Oxidase (Cytochrome d) in Escherichia coli K12: Optical Studies of Intermediate Species and Cytochrome b Oxidation at sub-zero Temperatures
More LessOptical changes in d- and b-type cytochromes, following initiation of the reaction of cytochrome oxidase d with O2, have been studied in cells and derived membrane particles from oxygen-limited cultures of Escherichia coli K12. At successively higher temperatures between − 132 and − 88 °C, the first scan after photolysis of the CO-liganded, reduced oxidase in the presence of O2 shows a diminution of cytochrome d 650 (believed to be an early intermediate in the O2 reaction) and a slow increase in absorbance at 675 to 680 nm due to an unidentified chromophore. A similar sequence occurs when a single sample is scanned repetitively at − 91 °C. At higher temperatures, oxidation of at least two spectrally distinct cytochromes b occurs. Selective photolysis of the cytochrome d-CO complex with a He-Ne laser shows that neither of these cytochromes is the CO-binding cytochrome o 436. In all oxidation states examined, no absorbance in the 720 to 860 nm region was observed; it is concluded that both cytochromes d and o 436 lack redox-active copper that has an environment similar to the copper(s) in mitochondrial cytochrome c oxidase.
The amount of cytochrome d 650 (but not the amount of reduced cytochrome o 436) formed after photolysis is directly proportional to the oxygen concentration in the sample at the time of freeze trapping. The results are discussed in relation to the composition and mechanism of action of cytochrome d.
-
-
-
Substrate Phosphorylation in Chlorobium vibrioforme f. sp. thiosulfatophilum
More LessChlorobium vibrioforme f. sp. thiosulfatophilum was shown to oxidize sulphate via substrate phosphorylation involving adenylylsulphate (APS) reductase, ADP-sulphurylase and adenylate kinase. APS reductase was purified 200-fold and shown to be a flavoprotein of molecular weight 1·8 × 105, containing 1 mol flavin adenine dinucleotide (FAD), 4–6 mol non-haem iron and 6–8 mol labile sulphide (mol enzyme)−1. Substrate inhibition of the enzyme was observed when the AMP concentration was above 2 mm. ADP-sulphurylase purified free of adenylate kinase had an apparent K m value for APS of 0·25 mm, which increased with decreasing concentrations of phosphate.
-
-
-
Glycerol Catabolic Enzymes and Their Regulation in Wild-type and Mutant Strains of Streptomyces coelicolor A3(2)
More LessAssay procedures were developed for a soluble glycerol kinase [apparent K m (glycerol) 9 μm] and a probably membrane-associated, NAD-independent l-glycerol-3-phosphate dehydrogenase [apparent K m (l-glycerol 3-phosphate) 7 mM] present in Streptomyces coelicolor A3(2). Both enzymes were cold sensitive. They were co-ordinately induced (about 35-fold) by addition of glycerol to cultures growing on arabinose as sole carbon source. Induction was rifampicin sensitive. The dehydrogenase was absent from glycerol-sensitive mutants, and both kinase and dehydrogenase were absent from glycerol non-utilizing (but glycerol-resistant) mutants, demonstrating that the two enzymes are part of the major pathway of glycerol catabolism in S. coelicolor. Circumstantial evidence suggested that their inducer is glycerol 3-phosphate rather than glycerol. The enzymes were subject to co-ordinate repression by various carbon sources, of which glucose exerted the strongest effect (a fivefold repression). Previously described mutants resistant to 2-deoxyglucose, shown here to have very low glucose kinase activity, were defective in glucose repression of the glycerol enzymes.
-
-
-
Catabolic Pathways for Glucose, Glycerol and 6-Phosphogluconate in Mycobacterium leprae grown in Armadillo Tissues
More LessWith radioisotopes, it was shown that suspensions of Mycobacterium leprae oxidized glycerol, 6-phosphogluconate, glucose, glucose 6-phosphate, and, at a low rate, gluconate, to CO2. The incubation period in these experiments was usually 20 h, but after 140 h up to five times more glucose and gluconate had been converted to CO2. Studies with differentially labelled glucose indicated that glycolysis and the hexose monophosphate pathway were used for glucose dissimilation.
Key enzymes of glycolysis, the hexose monophosphate pathway and glycerol catabolism were detected in cell-free extracts from purified M. leprae, but phosphoketolase, Entner-Doudoroff pathway activity and gluconate kinase were absent. All these enzymes were present also in host-tissue, but biochemical evidence is presented which indicates that all enzymes detected in extracts from M. leprae were authentic bacterial enzymes. Additionally, they could all be detected in extracts of M. leprae prepared by treatment with NaOH in which host enzymes adsorbed to M. leprae are inactivated.
-
-
-
Comparative Biochemistry of the Cell Envelopes of Photobacterium leiognathi and Escherichia coli
More LessPhotobacterium leiognathi closely resembles Escherichia coli with respect to cell lysis by lysozyme, and the fractionation of outer and cytoplasmic membranes. The two organisms differ in their phospholipid contents and, more significantly, in outer membrane protein compositions.
-
- Development And Structure
-
-
-
A Comparison of the Macrocyst and Fruiting Body Developmental Pathways in Dictyostelium discoideum
More LessSeveral differences and similarities between the macrocyst and fruiting body pathways of development are described. First, as has been long assumed, starvation initiates the development of amoebae for both pathways. Second, amoebae make the decision to produce macrocysts or fruiting bodies before a critical time point approximately 12 h after the onset of starvation. After this time, amoebae are committed to fruiting body development. Substances that can push amoebae into one or the other pathway often do so by altering the timing of development. Finally, cell division may be required in order for amoebae to become competent to produce macrocysts; there is no such requirement for fruiting body development.
-
-
- Ecology
-
-
-
Thiobacilli of the Corroded Concrete Walls of the Hamburg Sewer System
More LessThiobacilli were estimated in samples taken from the Hamburg sewer system at six sites showing different degrees of concrete corrosion. There was a marked enrichment of thiobacilli on the sewer pipe surface above the sewage level in comparison to the liquid phase. The highest number [108 thiobacilli (mg protein)−1] was found at the site of the greatest corrosion. Ten isolates of the genus Thiobacillus were characterized and identified as Thiobacillus neapolitanus, T. thiooxidans, T. intermedius and T. novellus. Facultative chemolithotrophic bacteria predominated at sites of early corrosion, whereas T. thiooxidans was most abundant in severely corroded areas. The cell number of T. thiooxidans could be greatly decreased by aerating the sewage with pure oxygen.
-
-
- Genetics And Molecular Biology
-
-
-
The Size and Structure of the DNA Genome of Symbiont Xenosome Particles in the Ciliate Parauronema acutum
More LessThe size and structure of the DNA genome of xenosomes, bacterial endosymbionts of the marine hymenostome ciliate, Parauronema acutum 110–3, were investigated. Renaturation kinetic measurements, determined optically and by hydroxyapatite chromatography, suggested a genome size of 0·34 × 109 daltons. Sedimentation rate measurements of DNA gently released from the symbionts yielded molecules of comparable size. The analytical complexity, determined chemically, was 3·03 × 109 daltons. Consistent with these and other data is a model for the structure of the symbiont genome in which the DNA exists in the form of nine circularly permuted, double-stranded DNA molecules of unique sequence, each of molecular weight 0·34 × 109. It is suggested that xenosomes and certain symbionts found in ciliated protozoa may be extant forms of once free-living bacteria that have adapted to the intracellular environment.
-
-
-
-
Genetic Interactions in Streptomyces rimosus Mediated by Conjugation and by Protoplast Fusion
More LessThe development of a protoplast fusion technique for oxytetracycline-producing Streptomyces rimosus strains, and its evaluation for the application for a breeding programme, has been described. Treatment of S. rimosus protoplasts with 40% (w/v) PEG 1550 for 30 min gave optimal numbers of recombinants ranging from 1 to 10% of the total progeny. Therefore, by comparison with conjugation, protoplast fusion increased the frequency of recombination by two to three orders of magnitude. The proportion of multiple crossover classes amongst recombinants was higher, by a factor of ten, after protoplast fusion (13·3%) than after conjugation (1·5%). Participation of less frequent complementary genotype doubled from 9·0% in conjugation to 17·9% in protoplast fusion. Overall, this suggested that the opportunities for crossing over in a fusion of S. rimosus protoplasts were spatially and/or temporally extended leading to a loosening of linkage with a near-random assortment of genotypes in a cross. However, by minimizing the multiple crossover classes and calculating allele frequency gradients, it was shown that the protoplast fusion technique allows arrangement of genetic markers on the S. rimosus chromosome. These are ideal characteristics for the recombination of divergent lines in a strain improvement programme.
-
-
-
The Mechanism of Insertion of a Segment of Heterologous DNA into the Chromosome of Bacillus subtilis
More LessAn Escherichia coli plasmid, p1949, that is derived from pMB9 and pC194, and unable to replicate in Bacillus subtilis, can give rise to stable CmR transformants of the latter species if it is inserted into the bacterial chromosome. A purified segment of the B. subtilis chromosome, with transforming activity against pheA1 and nic-38 recipients, was used to direct the insertion of p1949 into the B. subtilis chromosome. Insertion of the ligated DNA segments occurred in the region of the chromosome from which the purified phe-nic segment was derived. Many of the properties of the resulting CmR transformants of B. subtilis are consistent with the occurrence of a Campbell recombination mechanism leading to integration. However, certain of these properties are more easily explained if it is proposed that integration occurs by a reciprocal recombination event involving a linear ligation product. Evidence is presented suggesting that the inserted sequences may be tandemly duplicated. This may effectively vitiate the use of p1949 as a convenient means for complementation analysis of recessive mutations in B. subtilis.
-
-
-
A Cryptic Plasmid from Shigella sonnei
More LesspNZ500 is a 1.5 kb cryptic plasmid from a Shigella sonnei isolate. It was introduced into Escherichia coli by cotransformation, where it is maintained at about 30 copies per chromosome equivalent. Hybridization studies show that pNZ500 exhibits a high level of sequence similarity to other 1.5 kb plasmids found in different S. sonnei isolates but shares no homology with larger S. sonnei plasmids. pNZ500 shares a small degree of sequence homology with pBR322 and with pAC184. The homology with pBR322 is restricted to sequences close to the ori-bom region of this plasmid. Nevertheless, pNZ500 maintenance in E. coli is not dependent on DNA polymerase I activity, and does depend on continuing protein synthesis. pNZ500 encodes two polypeptide gene products whose monomer molecular weights are 24500 and 18000. The examination of host cells for the expression of possible plasmid phenotypes revealed no differences between cells bearing pNZ500 and plasmidless cells.
-
-
-
Identification of Tn2401, a Transposon Encoding Multiresistance to Aminoglycosides
More LessA transposable element, Tn2401, was found in a clinical isolate of Pseudomonas aeruginosa. Tn2401 had a size of 7190 nucleotides and encoded aminoglycoside 3′-phosphotransferase and aminoglycoside 6′-N-acetyltransferase. The sequence encoding the former enzyme was homologous with that of Tn903. Pseudomonas aeruginosa strains harbouring this transposon were resistant to kanamycin, neomycin, lividomycin, ribostamycin, paromomycin, netilmycin, tobramycin, dibekacin, gentamicin, sisomicin, and butirosin.
-
- Pathogenicity And Medical Microbiology
-
-
-
Effects of pH on Biomass, Maximum Specific Growth Rate and Extracellular Enzyme Production by Three Species of Cutaneous Propionibacteria Grown in Continuous Culture
More LessThree cutaneous propionibacteria, Propionibacterium acnes, Propionibacterium avidum and Propionibacterium granulosum, were grown in chemostats using semi-synthetic medium at various pH values. Growth occurred between pH 4·5 and 7·5 for P. acnes and pH 5·0 and 8·0 for P. avidum and P. granulosum. The highest μ max was at pH 6·0 for the three species. Maximum biomass production was obtained at pH 6·0 for P. acnes and P. avidum and at pH 7·5 for P. granulosum. Extracellular enzyme production occurred over the entire pH growth range when denaturation of the enzymes was taken into account. However, detectable activity of the enzymes was found in a narrower range of pH due to the denaturation of the enzymes at low or high pH values. The highest production of enzymes occurred at pH values between 5·0 and 6·0, apart from the production of hyaluronate lyase of P. granulosum (pH 6·0 to 7·0) and the proteinase of P. acnes and P. avidum (pH 5·0 to 7·5). Propionibacterium acnes produced a lipase, hyaluronate lyase, phosphatase and proteinase activity. Propionibacterium avidum produced a lipase and proteinase activity. Propionibacterium granulosum produced a lipase and hyaluronate lyase.
-
-
-
-
Kinetics of Adherence of Actinomyces viscosus to Saliva-coated Silica and Hydroxyapatite Beads
More LessAdherence of 14C-labelled strains of Actinomyces viscosus to uncoated and saliva-coated silica and hydroxyapatite beads had both loose and firm components, probably reflecting different subpopulations of bacteria within a single culture. Adherence was characterized by the proportion of bacteria available for each type of adherence and a constant (K b) for each combination of bacterial strain and bead surface. Loose adherence, which was greater with silica than with hydroxyapatite beads, always involved many more bacteria than firm adherence. Firm adherence was greater with A. viscosus WVU627 than A. viscosus TF11. The association rate constants (K a) for loose and firm adherence were similar, indicating simultaneous processes, but the dissociation rate constant (K d) was lower for loose adherence than for firm adherence. Removal of loosely adhering bacteria by washing may only reflect their distance from the bead surface. Silica beads were convenient for studying bacterial adherence and formed an acceptable coating of salivary glycoprotein.
-
-
-
Altered Colonizing Ability for Mouse Large Intestine of a Surface Mutant of a Human Faecal Isolate of Escherichia coli
More LessEscherichia coli F-17 Sr a human faecal isolate, is resistant to the T-series of bacteriophages (i.e. T2 to T7). A T2-sensitive mutant of E. coli F-17 Sr was isolated following acriflavin treatment. This mutant, E. coli F-17 Sr Ts was found to be sensitive to the entire T-series of phages. E. coli F-17 Sr and E. coli F-17 Sr Ts did not differ quantitatively in total LPS content. However, analysis of LPS revealed that a large fraction of E. coli F-17 Sr Ts was devoid of O-side-chains. This accounted for the sensitivity of this strain to bacteriophages T3, T4, and T7. In addition, E. coli F-17 Sr Ts contained only about half the amount of capsular material contained by E. coli F-17 Sr accounting for the sensitivity of the mutant to bacteriophages T2, T5, and T6. Although the two strains colonized equally well when fed individually to streptomycin-treated mice, when fed simultaneously to streptomycin-treated mice, E. coli F-17 Sr Ts colonized at a level of about 1 × 108 cells (g faeces)−1, whereas E. coli F-17 Sr colonized at only 1 × 104 cells (g faeces)−1. These studies suggest that bacterial cell surface components modulate the large intestine colonizing ability of E. coli F-17 Sr in the mouse large intestine.
-
-
-
Surface Antigens of Gonococci: Correlation with Virulence and Serum Resistance
More LessEncapsulated and non-encapsulated variants of one strain of gonococcus were compared for their capacity to produce infection in chambers implanted subcutaneously in mice, for their reactions with specific antibody and for their precipitation with wheat germ agglutinin. Only the encapsulated variant could infect implanted chambers. Specific rabbit antiserum raised against the non-encapsulated variant killed only that variant, whereas antibody raised against the encapsulated variant killed both variants.
Saline extracts and lipopolysaccharide preparations of the encapsulated variant differed from those of the non-encapsulated one in their reactions with wheat germ agglutinin and antibody in diffusion and electrophoresis tests. Preparations from infective encapsulated gonococci reacted with wheat germ agglutinin while those from the non-encapsulated variant did not. Immunodiffusion tests showed that lipopolysaccharides from both variants share a common antigenic determinant, but saline extracts and lipopolysaccharides from encapsulated gonococci possess an additional determinant. The significance of these findings is discussed.
-
- Physiology And Growth
-
-
-
Regulation of Enzyme Synthesis and Variation of Residual Methanol Concentration during Carbon-limited Growth of Kloeckera sp. 2201 on Mixtures of Methanol and Glucose
More LessThe methylotrophic yeast Kloeckera sp. 2201 was grown in double carbon (glucose/methanol) limitation in a chemostat at a constant dilution rate and the regulation of the synthesis of enzymes involved in the assimilation of methanol and the breakdown of glucose was studied as a function of the composition of the glucose/methanol mixture in the inflowing medium. Enhanced synthesis of most of the enzymes taking part in the assimilation of C1 units took place despite the presence of glucose in the medium. Depending on the enzyme, 40 to 60% (w/w of total substrate) methanol in the mixture was enough to cause maximal induction and no further enhancement of their specific activities was observed during growth on mixtures containing higher methanol/glucose ratios. The only two enzymes involved in the assimilation of methanol not showing these characteristic patterns were classical transketolase and transaldolase. substrate fluxes through the individual steps of glucose and methanol metabolism have been calculated and compared with the experimentally determined specific activities of the enzymes concerned. The three enzymes whose specific activities were least in excess of the substrate flux calculated to be catalysed by them were transketolase, transaldolase and (possibly) dihydroxyacetone synthase.
The residual concentration of methanol was measured in the culture as a function of the composition of the supplied glucose/methanol mixture. During growth with mixtures the concentration of methanol was always lower than during growth with this substrate as the only carbon source. Possible ecological advantages accruing to a facultative methylotroph as a consequence of this behaviour are discussed.
-
-
-
-
Fermenter Growth of Streptococcus agalactiae and Large-scale Production of CAMP Factor
More LessStreptococcus agalactiae (group B) was grown in Todd-Hewitt broth (36·4 g 1−1, pH 7·8) in a Braun Fermenter (type B20) to investigate the conditions of optimal bacterial growth and maximal production of CAMP factor. The influence of different gas atmospheres (air, N2, CO2, and gas mixtures) on growth, CAMP production and chain length of S. agalactiae was studied. The organisms grew best in the presence of 2% (w/v) glucose, at pH 6·2, with a constant flow of CO2. The number of diplococci and monococci under these conditions reached almost 80% of the total population.
-
-
-
Sporulation and Spore Properties of Bacillus brevis and its Gramicidin S-negative Mutant
More LessThe function(s) of the peptide antibiotic, gramicidin S, in its producer, Bacillus brevis Nagano, was investigated. Particular attention was paid to the possible role of gramicidin S in sporulation and spore properties. Sporulation was similar in both the gramicidin S-producing parental strain and a gramicidin S-negative mutant of this strain. Mature parental and mutant spores were equally resistant to UV irradiation, solvents (reported previously) and heat. Thus, the lack of gramicidin S synthesis impairs none of these properties. Contrary to results reported by others, we also found no difference in heat resistance between spores of B. brevis ATCC 8185 and its linear gramicidin-negative mutant, Ml.
-
-
-
The SHAM-sensitive Alternative Oxidase in Tetrahymena pyriformis: Activity as a Function of Growth State and Chloramphenicol Treatment
More LessThe SHAM-sensitive alternative oxidase has been studied in Tetrahymena pyriformis strain ST as a function both of growth state and of chloramphenicol treatment. In low density cultures the total alternative oxidase activity, as revealed by SHAM titration in the presence of CN−, is equivalent to 17% of total respiration and is slightly utilized at all times. Stationary phase cells have somewhat less of the oxidase and it is not utilized even in CCCP-uncoupled cells. Respiration in chloramphenicol-treated cells is 100% CN−-resistant. Alternative oxidase activity is equivalent to 30-40% of this total and one third of it is active. The remaining 60% residual respiration is due to unknown oxidases. Following CCCP-uncoupling, a CN−-sensitive pathway is demonstrable and the alternative oxidase is fully utilized. The higher proportion of alternative oxidase in chloramphenicol-treated cells is brought about by its conservation at a time when the cytochrome chain is becoming non-functional. There is no large scale induction of the alternative oxidase.
-
-
-
Solute Uptake by Dictyostelium discoideum and its Inhibition
More LessA study has been made of the uptake of radioactively-labelled solutes by starved myxamoebae of the cellular slime mould Dictyostelium discoideum. Inulin uptake was energy-dependent, inhibited by cycloheximide, and the rate was proportional to extracellular inulin concentration. The ability of the cells to take up inulin did not change during starvation. Uptake of four other solutes, β-alanine, glucose, protein hydrolysate and uracil occurred at a similar rate to inulin uptake when expressed as an endocytic index (μl medium taken up h−1 per 106 cells). All the results were consistent with uptake occurring by fluid-phase pinocytosis. Pinocytic activity thus occurred in starving cells and was found to be affected by some agents that act as developmental inhibitors. Uptake of inulin and putrescine (previously shown to be taken up by adsorptive pinocytosis) was inhibited by chloroquine, KCl and NH4Cl, although ammonium ions also blocked developmental changes in the ability of myxamoebae to take up putrescine. Sodium ions were less inhibitory. ε-Aminocaproic acid inhibited solute uptake in a temperature-dependent, reversible manner.
-
-
-
Isolation and Partial Characterization of α Hormones Produced by Phytophthora parasitica
More LessMillipore filters placed underneath agar block cultures of Phytophthora parasitica were able to adsorb hormones α1 and α2 produced by A1 and A2 mating types of the fungus, respectively. Both hormones were released from moistened Millipore filters by extraction with ether, which on evaporation resulted in aqueous hormone extracts. Isolated hormones α1 and α2 stimulated oospore formation by A2 and A1 mating types of P. parasitica, respectively, when they were adsorbed on small pieces of Millipore filter, but not when they were added directly to agar cultures. Hormones α1 and α2 were removed from aqueous solutions by both cation and anion exchange resins, and could be eluted from the resins by ether. Both hormones α1 and α2 were able to pass through membranes with a molecular weight cut-off of 1000 and 500, but not 100 and 50.
-
-
-
31P Nuclear Magnetic Resonance Study of Growth and Dimorphic Transition in Candida albicans
More LessA 31P NMR study of the fungal pathogen Candida albicans was carried out. Yeast-form cells at different phases of growth, as well as germ tubes and hyphae were examined. In all cases, the NMR spectra showed well separated resonance peaks arising from phosphorus-containing metabolites, the most prominent being attributable to inorganic phosphate (Pi) polyphosphates, sugar phosphates and mononucleotides, NAD, ADP and ATP. Relevant signals were also detected in the phosphodiester region. The intensity of most signals, as measured relative to that of Pi, was clearly modulated both at the different phases of growth and during yeast-to-mycelium conversion, suggesting significant changes in the intracellular concentration of the corresponding metabolites. In particular, the intensity of the polyphosphate signal was high in exponentially growing, yeast-form cells, then progressively declined in the stationary phase, was very low in germ tubes and, finally, undetectable in hyphae.
NMR spectral analysis of the Pi region showed that from early-stationary phase, Pi was present in two different cellular compartments, probably corresponding to the cytoplasm and the vacuole. From the chemical shift of Pi, the pH values of these two compartments could be evaluated. The cytoplasmic pH was generally slightly lower than neutrality (6·7–6·8), whereas the vacuolar pH was always markedly more acidic.
-
-
-
Calcofluor White Alters the Assembly of Chitin Fibrils in Saccharomyces cerevisiae and Candida albicans Cells
More LessIn the presence of calcofluor white, budding scars and dividing cross-walls of Saccharomyces cerevisiae exhibited fluorescence, indicating that the brightener was a specific marker of fungal chitin. In addition, incubation of cells in the presence of the brightener did not stop protein and wall-polymer formation, but abnormal deposition of chitin occurred. Chitin synthesis was normal in regenerating protoplasts of Candida albicans in the presence of calcofluor, but formation of the crystalline lattice was blocked. These results suggest that crystallization of nascent subunits may occur by a self-assembly mechanism that was blocked by the stain.
-
- Short Communication
-
-
-
α-Factor Enhancement of Hybrid Formation by Protoplast Fusion in the Yeast Saccharomyces cerevisiae
More LessTwo a strains of Saccharomyces cerevisiae, carrying complementary genetic markers, were arrested for 3 h with α-factor. These were then protoplasted, prior to fusion using polyethylene glycol. The number of viable fusion products was enhanced by a factor of 20 as compared with unarrested controls.
-
-
-
-
Structural Variations in Pili Expressed during Gonococcal Infection
More LessGonococci were cultured from the urethra of male patients and from the cervix and urethra of their female partners. SDS-PAGE of cell lysates from within each group of consorts showed that outer membrane protein I remained constant but considerable variations were seen in the apparent molecular weight of protein II. Pili were purified from the isolates of some groups of consorts. In each case the pili expressed by the isolates from the female cervix and urethra differed in subunit molecular weight and were usually also distinct from the pili expressed by the isolate from the male partner.
-
- Taxonomy
-
-
-
Taxonomic Studies on Some Group D Streptococci
More LessBiochemical, menaquinone, fatty acid and DNA analyses were conducted on a number of streptococci of serological group D. The results indicate that S. faecalis, S. faecium, S. casseliflavus and taxa previously designated ‘S. avium’, ‘S. durans’ and ‘S. faecalis var. malodoratus’ are distinct species. Strains previously labelled ‘S. faecium var. mobilis’ were shown to be identical with S. casseliflavus. The results also indicate that some group D streptococci recently isolated from chickens constitute a new species.
-
-
-
-
Identification Key for Coryneform Bacteria Derived by Numerical Taxonomic Studies
More LessSix main groups were formed from a complete linkage dendrogram on 557 bacteria tested for 53 physiological features. The organisms were obtained from culture collections and included representatives of the following genera: Arthrobacter, Brevibacterium, Caseobacter, Cellulomonas, Corynebacterium, Curtobacterium, Micrococcus, Microbacterium, Mycobacterium, Nocardia, Oerskovia and Rhodococcus. The six groups were individually subjected to a numerical taxonomic analysis based on linkage maps, which resulted in a total of 33 subclusters. An identification key to determine the affiliation of the bacteria to the six main clusters and five group-specific schemes is presented. Reference strains are proposed for the 33 subclusters.
-
-
-
Taxonomic Relationships among Clostridium novyi Types A and B, Clostridium haemolyticum and Clostridium botulinum Type C
More LessThe present study was undertaken to examine the genetic relationships among the closely related species, Clostridium novyi types A and B, C. haemolyticum and C. botulinum type C. These species were tested for DNA-DNA homology and thermostability of DNA duplexes and sorted into three genetically related groups: I, C. novyi type A; II, C. novyi type B, C. haemolyticum and one C. botulinum type C strain (Stockholm); III, the remaining C. botulinum type C strains. A few biochemical criteria corresponding to the genetic differences were recommended to differentiate each group. These studies imply that C. haemolyticum might be considered as C. novyi type D and that there are two genetically different groups in C. botulinum type C.
-
-
-
Characterization of an Effective Salt-tolerant, Fast-growing Strain of Rhizobium japonicum
More LessRhizobium japonicum USDA191 is a member of a new group of Rhizobium japonicum strains found in China. This strain is one of several strains shown to be salt-tolerant and fast-growing; it is unique in being the only strain of this group that effectively nodulates American soybean cultivars. For these reasons strain USDA191 was chosen for further study and comparison to the common American Rhizobium japonicum isolate USDA110. Strain USDA191 has a doubling time of 3.2 h in complex medium and grows in concentrations of up to 0·4 m-NaCl, while strain USDA110, which has a doubling time of 12 h, is severely inhibited in media containing 0·1 m-NaCl. Under salt stress conditions, intracellular levels of K+ and glutamate were shown to increase. A comparison based on carbohydrate metabolism, DNA homology and protein patterns on polyacrylamide gels reveals that strain USDA191 is more closely related to the fast-growing rhizobia than to Rhizobium japonicum. However, the strain retains capacity to nodulate American soybean and cowpea cultivars effectively.
-
- Corrigendum
-
Volumes and issues
-
Volume 170 (2024)
-
Volume 169 (2023)
-
Volume 168 (2022)
-
Volume 167 (2021)
-
Volume 166 (2020)
-
Volume 165 (2019)
-
Volume 164 (2018)
-
Volume 163 (2017)
-
Volume 162 (2016)
-
Volume 161 (2015)
-
Volume 160 (2014)
-
Volume 159 (2013)
-
Volume 158 (2012)
-
Volume 157 (2011)
-
Volume 156 (2010)
-
Volume 155 (2009)
-
Volume 154 (2008)
-
Volume 153 (2007)
-
Volume 152 (2006)
-
Volume 151 (2005)
-
Volume 150 (2004)
-
Volume 149 (2003)
-
Volume 148 (2002)
-
Volume 147 (2001)
-
Volume 146 (2000)
-
Volume 145 (1999)
-
Volume 144 (1998)
-
Volume 143 (1997)
-
Volume 142 (1996)
-
Volume 141 (1995)
-
Volume 140 (1994)
-
Volume 139 (1993)
-
Volume 138 (1992)
-
Volume 137 (1991)
-
Volume 136 (1990)
-
Volume 135 (1989)
-
Volume 134 (1988)
-
Volume 133 (1987)
-
Volume 132 (1986)
-
Volume 131 (1985)
-
Volume 130 (1984)
-
Volume 129 (1983)
-
Volume 128 (1982)
-
Volume 127 (1981)
-
Volume 126 (1981)
-
Volume 125 (1981)
-
Volume 124 (1981)
-
Volume 123 (1981)
-
Volume 122 (1981)
-
Volume 121 (1980)
-
Volume 120 (1980)
-
Volume 119 (1980)
-
Volume 118 (1980)
-
Volume 117 (1980)
-
Volume 116 (1980)
-
Volume 115 (1979)
-
Volume 114 (1979)
-
Volume 113 (1979)
-
Volume 112 (1979)
-
Volume 111 (1979)
-
Volume 110 (1979)
-
Volume 109 (1978)
-
Volume 108 (1978)
-
Volume 107 (1978)
-
Volume 106 (1978)
-
Volume 105 (1978)
-
Volume 104 (1978)
-
Volume 103 (1977)
-
Volume 102 (1977)
-
Volume 101 (1977)
-
Volume 100 (1977)
-
Volume 99 (1977)
-
Volume 98 (1977)
-
Volume 97 (1976)
-
Volume 96 (1976)
-
Volume 95 (1976)
-
Volume 94 (1976)
-
Volume 93 (1976)
-
Volume 92 (1976)
-
Volume 91 (1975)
-
Volume 90 (1975)
-
Volume 89 (1975)
-
Volume 88 (1975)
-
Volume 87 (1975)
-
Volume 86 (1975)
-
Volume 85 (1974)
-
Volume 84 (1974)
-
Volume 83 (1974)
-
Volume 82 (1974)
-
Volume 81 (1974)
-
Volume 80 (1974)
-
Volume 79 (1973)
-
Volume 78 (1973)
-
Volume 77 (1973)
-
Volume 76 (1973)
-
Volume 75 (1973)
-
Volume 74 (1973)
-
Volume 73 (1972)
-
Volume 72 (1972)
-
Volume 71 (1972)
-
Volume 70 (1972)
-
Volume 69 (1971)
-
Volume 68 (1971)
-
Volume 67 (1971)
-
Volume 66 (1971)
-
Volume 65 (1971)
-
Volume 64 (1970)
-
Volume 63 (1970)
-
Volume 62 (1970)
-
Volume 61 (1970)
-
Volume 60 (1970)
-
Volume 59 (1969)
-
Volume 58 (1969)
-
Volume 57 (1969)
-
Volume 56 (1969)
-
Volume 55 (1969)
-
Volume 54 (1968)
-
Volume 53 (1968)
-
Volume 52 (1968)
-
Volume 51 (1968)
-
Volume 50 (1968)
-
Volume 49 (1967)
-
Volume 48 (1967)
-
Volume 47 (1967)
-
Volume 46 (1967)
-
Volume 45 (1966)
-
Volume 44 (1966)
-
Volume 43 (1966)
-
Volume 42 (1966)
-
Volume 41 (1965)
-
Volume 40 (1965)
-
Volume 39 (1965)
-
Volume 38 (1965)
-
Volume 37 (1964)
-
Volume 36 (1964)
-
Volume 35 (1964)
-
Volume 34 (1964)
-
Volume 33 (1963)
-
Volume 32 (1963)
-
Volume 31 (1963)
-
Volume 30 (1963)
-
Volume 29 (1962)
-
Volume 28 (1962)
-
Volume 27 (1962)
-
Volume 26 (1961)
-
Volume 25 (1961)
-
Volume 24 (1961)
-
Volume 23 (1960)
-
Volume 22 (1960)
-
Volume 21 (1959)
-
Volume 20 (1959)
-
Volume 19 (1958)
-
Volume 18 (1958)
-
Volume 17 (1957)
-
Volume 16 (1957)
-
Volume 15 (1956)
-
Volume 14 (1956)
-
Volume 13 (1955)
-
Volume 12 (1955)
-
Volume 11 (1954)
-
Volume 10 (1954)
-
Volume 9 (1953)
-
Volume 8 (1953)
-
Volume 7 (1952)
-
Volume 6 (1952)
-
Volume 5 (1951)
-
Volume 4 (1950)
-
Volume 3 (1949)
-
Volume 2 (1948)
-
Volume 1 (1947)