- Volume 128, Issue 5, 1982
Volume 128, Issue 5, 1982
- Biochemistry
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Glucose Metabolism in Xanthomonas campestris
More LessThe pathways of glucose metabolism in Xanthomonas campestris closely resemble those described for Pseudomonas aeruginosa, in which two discrete systems exist for the uptake of glucose, one periplasmic and oxidative requiring glucose dehydrogenase activity, the second intracellular and phosphorylative. These systems lead to the production of 6-phosphogluconate, which may be metabolized via the Entner-Doudoroff pathway and the pentose phosphate pathway. Terminal oxidation is mediated by the tricarboxylic acid cycle. A mucoid strain of X. campestris lacked glucose dehydrogenase activity and thus the oxidative pathway was not functional; the pentose phosphate pathway was also inoperative in this strain, as evidenced by the absence of 6-phosphogluconate dehydrogenase activity. Nonmucoid mutants appeared identical to the parent strain; however, a second group of mutants (crenated mutants) were derepressed for both glucose dehydrogenase and 6-phosphogluconate dehydrogenase. Gluconate kinase was not detected in any of the X. campestris strains studied when grown on glucose; however, growth of the parent strain on gluconate resulted in the induction of this enzyme.
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Naphthalene Metabolism by Diatoms Isolated from the Kachemak Bay Region of Alaska
More LessThree pure cultures of diatoms - a Navicula sp., a Nitzschia sp. and a Synedra sp. - grown in the presence of naphthalene at 6 or 12 °C oxidized the naphthalene to ethyl acetate-soluble and water-soluble metabolites. The major ethyl acetate-soluble metabolite was identified as 1-naphthol by gas chromatographic and mass spectral analysis. Experiments with [14C]naphthalene indicated that the extent of naphthalene metabolism ranged from 0·7 to 1·4 %.
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More Than One Amine Oxidase is Involved in the Metabolism by Yeasts of Primary Amines Supplied as Nitrogen Source
More LessTwenty-seven yeast species were tested for growth on methylamine and n-butylamine as sole nitrogen sources. Five species (including Saccharomyces cerevisiae) failed to grow on either amine, and a further five grew only on n-butylamine. The remainder grew on both amines. Amine oxidase activity was detected in extracts of all the strains which could grow on amines, but was generally absent from cells grown on ammonia or nitrate. From measurements in cell-free extracts of oxidase activity for a number of different amines, it is concluded that most such strains have at least two amine oxidases of different substrate specificity, and that the substrate specificity also varies between different yeast species. Based on these observations, four different groups of yeasts could be distinguished. Formaldehyde dehydrogenase activity was elevated in cells grown on amines or nitrate compared with those grown on ammonia, and activity was generally higher in cells grown on methylamine than in those grown on n-butylamine or nitrate.
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Oxygen Affinities of the Hydrogenosome-containing Protozoa Tritrichomonas foetus and Dasytricha ruminantium, and Two Aerobic Protozoa, Determined by Bacterial Bioluminescence
More LessOxygen-dependent bioluminescence of Photobacterium (Vibrio) fischeri was used to measure oxygen affinities of four protozoa. The aerobic organisms Acanthamoeba castellanii and Tetrahymena pyriformis showed apparent K m values for O2 of 0·42 and 2·43 μm respectively. The aerotolerant anaerobe Tritrichomonas foetus, and the more strictly anaerobic rumen ciliate Dasytricha ruminantium, both of which have hydrogenosomes, respired with apparent K m values of 1·08 and 1·70 μm-O2. We conclude that mitochondrial respiration is not the only process conferring on organisms a high affinity for O2.
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Role of Glutathione in the Regulation of Inorganic Pyrophosphatase Activity in Streptococcus faecalis
More LessWhen the thiol-oxidizing agent diamide was added to a batch culture of Streptococcus faecalis during exponential growth, the specific activity of inorganic pyrophosphatase (EC 3·6·1·1) decreased to the level observed in the stationary phase. The effect of diamide was completely reversed by reduced glutathione. Furthermore, the ratio of reduced to oxidized glutathione and the specific activity of inorganic pyrophosphatase changed in a very similar fashion during batch culture. These findings, together with our earlier results, suggest that the activity of inorganic pyrophosphatase in S. faecalis is regulated by glutathione via the ratio of reduced to oxidized glutathione.
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Utilization of Tetrathionate and 35S-labelled Thiosulphate by Washed Cells of Chlorobium vibrioforme f. sp. thiosulfatophilum
More LessThe utilization of S4O2- 6 by washed cells of Chlorobium vibrioforme f. sp. thiosulfatophilum was light-dependent. The stoichiometry for S4O2- 6 oxidation and 14CO2 assimilation was 1:3·5. Both processes were inhibited by O2, but this effect was partially reversed by flushing the reaction mixture with argon. A variety of inhibitors of thiol groups and electron transport, as well as uncouplers and ionophores, restricted these activities. During the oxidation of 35S-labelled S2O2- 3 by washed cells, the sulphone S atom (from S35SO2- 3) was rapidly oxidized to SO2- 4 via SO2- 3, whereas the first identifiable product of the oxidation of the sulphane S atom (from 35SSO2- 3) was S2- and then elemental sulphur, which was extruded into the medium and then reutilized and oxidized to SO2- 4. A number of inhibitors of thiol groups and respiratory carriers, as well as ionophores, also restricted the oxidation of S2O2- 3.
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Ergosterol and Lanosterol from Aspergillus nidulans
More LessErgosterol was identified as the major free sterol of Aspergillus nidulans by thin-layer chromatography, alumina column chromatography, gas-liquid chromatography, highperformance liquid chromatography, UV spectroscopy, proton magnetic resonance spectroscopy and mass spectral analysis. Lanosterol, the initial cyclized precursor of ergosterol, was identified as a minor component of the free sterols. In the steryl ester material, however, lanosterol was usually more abundant than ergosterol, suggesting that the esters serve as storage compounds for the membrane sterol precursors.
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Na+-Dependent Active Transport Systems for Organic Solutes in an Alkalophilic Bacillus
More LessTransport of nutrients (glutamate, glucose and acetate) into membrane vesicles of Bacillus sp. A-007 was specifically dependent on the Na+ gradient (outside high). The nutrients were co-transported with Na+, the process being stimulated by alkaline pH. In addition to the transport process, binding of glutamate to membrane vesicles was also pH- and Na+-dependent.
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N-Acetyl-β-glucosaminidase, β-Glucuronidase and Acid Phosphatase in Mycobacterium leprae
More LessN-Acetyl-β-glucosaminidase, β-glucuronidase and acid phosphatase activities were detected in cell-free extracts of Mycobacterium leprae (from armadillo liver). Extracts of bacteria which had been treated with 7-diazonaphthalene-1,3-disulphonic acid to inactivate surface enzymes retained 30–45% of the activity of the glycosidases and 15% of the activity of the acid phosphatase. When intact bacteria were treated with 1 m-NaOH, the corresponding activity in the extracts was 4–9% for the glycosidases and 7% for the acid phosphatase. Inhibition studies with lactones and the use of concanavalin A-agarose showed differences between the glycosidases in extracts of M. leprae and those of armadillo liver. Inhibition studies with vanadate using extracts from NaOH-treated bacteria and extracts of armadillo liver showed differences between the acid phosphatases. Enzymes removed from the surface of M. leprae could have been adsorbed to the surface from host tissue (i.e. lysosomal enzymes) or they could have been extracellular enzymes or associated with the bacterial membrane.
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Activities and Regulation of the Enzymes of Lysine Biosynthesis in a Lysine-excreting Strain of Bacillus megaterium
More LessLysine was excreted by Bacillus megaterium CII19 after growth in chemically defined media containing low concentrations of sulphate. Addition of more sulphate, or cysteine or methionine stopped lysine formation; instead ornithine was excreted. All the enzymes of the pathway leading from aspartate to lysine were assayed in extracts prepared from organisms grown in batch and continuous cultures (sulphur-or carbon-limited). The rate of the slowest step (tetrahydrodipicolinate acetylase) limited the rate of lysine synthesis to about 10 nmol min−1 (mg protein)−1, though none of the other enzymes was very much more active. Aspartokinase, aspartic β-semialdehyde dehydrogenase, dihydrodipicolinate synthase and N-acetyl-aminoketopimelate:glutamate aminotransferase were partly repressed by methionine; aspartokinase was also partly repressed by threonine. The aspartokinase repressed by methionine was inhibited by methionine plus lysine (though not by either amino acid singly), and the aspartokinase repressed by threonine was inhibited by threonine. None of the other repressible enzymes was inhibited by these amino acids. The activities of enzymes of glutamate and ornithine biosynthesis were very little altered by growth with limited or excess sulphate.
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Penicillin-Binding Proteins in the Soluble Fraction of Caulobacter crescentus
More LessFour penicillin-binding proteins (PBPs) were observed in the soluble fraction of Caulobacter crescentus CB13, and designated PBP S1 (mol. wt 60000), PBP S2 (55000), PBP S3 (45000) and PBP S4 (40000). Caulobacter crescentus CB15, an independent isolate, possessed similar soluble PBPs, but not PBP S2. These soluble PBPs could be observed even when a cell suspension was directly reacted with [14C]penicillin G. Two of the soluble PBPs, S1 and S2, released half their bound [14C]penicillin G during a 10 min incubation, indicating that these PBPs have penicillinase-like activity. PBP S2 was very thermolabile and lost its penicillin-binding activity after incubation at 40 °C for 10 min. Mecillinam did not show selective binding to any of the Caulobacter soluble PBPs or to PBPs in the cell envelope.
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Hydroxylation of Alkanes and Fatty Acids in Saccharomycopsis lipolytica. Evidence for the Involvement of Cytochrome P-450
More LessGrowth of the yeast Saccharomycopsis lipolytica on n-alkanes induced a hydroxylation system which, in the presence of NADPH and O2, converted lauric acid into ω-hydroxylauric acid. The specific hydroxylation activity was lower with the physiological substrate n-hexadecane than with lauric acid. This system was particulate and did not act on N-and O-dealkylated compounds. It was strongly inhibited by CO and its enzymic activity was unstable. Because of the presence of cytochrome oxidase in the preparations, spectral demonstration of the presence of cytochrome P-450 was difficult but could be achieved with the techniques developed.
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- Development And Structure
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Temperature-sensitive Mutant of Neurospora crassa that Affects Mycelial Growth and Morphology
More LessA temperature-sensitive mutant was isolated that conditionally affected the vegetative growth phase of the asexual developmental cycle of Neurospora crassa. The formation of aerial hyphae, conidiation and the initial steps of conidial germination were not temperature-sensitive in this strain. However, germ tube elongation was blocked at the restrictive temperature. The growth rate of the vegetative hyphae was greatly reduced and their morphology was altered when the hyphae grew on the surface of agar medium at 34 °C. These properties were not temperature-sensitive when the hyphae grew within the agar medium. In liquid medium, vegetative growth was temperature-sensitive when low concentrations of conidia (less than 104 ml−1) were used to inoculate the cultures. After a prolonged incubation at 34 °C, the cells died. The requirement for high cell densities for survival and growth in liquid medium at 34 °C could be overcome by adding histidine to the medium, but on agar medium containing histidine, the mutant strain still grew colonially at 34 °C. In addition to these temperature-sensitive properties, the mutant strain expressed a very strong circadian conidiation rhythm when grown on agar medium at 22 °C. The temperature-sensitive growth properties of the mutant strain and its ability to conidiate rhythmically reverted simultaneously to the wild-type phenotype. In forced heterokaryons, the mutant allele was recessive to the wild-type allele. The mutant allele was mapped on the right arm of linkage group IV.
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- Genetics And Molecular Biology
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Genetic Analysis by Mitotic Recombination in Dictyostelium discoideum of Growth and Developmental Loci on Linkage Group VII
More LessA genetic study was made of two developmental loci, stmA (mutations of which give ‘streamer’mutants with large aggregation territories) and fgdB (mutations of which give a class of ‘aggregateless’ mutant unable to respond to exogenous cyclic AMP signals), and three growth-related loci, couA, tsgK and bsgB (sensitivity to growth with coumarin, temperature sensitivity for growth and inability to grow on Bacillus subtilis, respectively). These loci, which have previously been located on linkage group VII, were found by mitotic recombination studies to lie proximal to the recombinant selector cobAl (resistance to cobaltous chloride) with the order: centromere-couA-tsgK-(stmA-bsgB)fgdB-cobA. Analysis of haploid segregants derived from 374 recombinant diploids allowed relative map distances to be calculated and revealed that tsgK, stmA, bsgB and fgdB lay as a loosely clustered group close to cobA. Two independently isolated mutations at another streamer locus, stmF, were found to be associated with a diploid instability phenomenon such that heterozygous (stmF/+) diploids which became homozygous at the cobA locus on linkage group VII by mitotic recombination reverted very rapidly to the haploid state. Reversion studies with the tsgK21 marker revealed that partial revertants (or suppressors) at this locus frequently introduced secondary developmental or growth-related mutations by an unexplained mechanism.
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Thermotactic Behaviour of Dictyostelium discoideum Slug Phototaxis Mutants
More LessBy isolating phototactic mutants also impaired in thermotaxis we have confirmed that the photosensory and thermosensory transduction pathways converge in Dictyostelium discoideum slugs. Novel features of behaviour of the mutant slugs, normally obscured in ‘wild type’ strains, are the extreme bimodal distribution of directions travelled during phototaxis, and the presence of a second transition from positive to negative thermotaxis at high temperature during migration in thermal gradients. The novel behaviours result from quantitative changes in the transition temperatures during thermotaxis and the preferred angles of deviation (±α) from the direction of the light source during phototaxis. The mutant slugs orient with reduced accuracy in both phototaxis and thermotaxis. These behaviour patterns are consistent with the outcome of mutations impairing signal processing after convergence of photosensory and thermosensory transduction pathways but before adaptation processes operate to set both the preferred directions in bidirectional phototaxis and the transition temperatures in thermotaxis.
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Mode of Action of Colicin S8
More LessThe mode of action of colicin S8 has been studied and compared with that of other colicins. Two minutes after the addition of colicin S8 to bacteria a considerable proportion of the colicin is inaccessible to trypsin. Treatment of bacteria with colicin S8 renders them more sensitive to lysis by sodium dodecyl sulphate and also inhibits motility. Like colicins K and E1, colicin S8 provokes lysis of bacteria superinfected with bacteriophage T4. Colicin S8, unlike colicin E2, prevents replication of bacteriophage T4. The incorporation of isoleucine or uracil into bacteria is inhibited by colicin S8 but, unlike colicins K and E1, the effect is multiplicity-dependent. A rapid method of titration of colicin S8 is described. The results are discussed with emphasis on the possible rearrangements at the bacterial surface and the possibility that there is more than one type of specific receptor for colicin S8.
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A Possible Regulatory Gene for the Molybdenum-Containing Cofactor in Aspergillus nidulans
More LessAspergillus nidulans has three molybdoenzvmes, nitrate reductase nitrate reductase, purine hydroxylase I and purine hydroxylase II. These three enzymes share a molybdenum-containing cofactor whose synthesis requires the inteegrity of five loci, designated cnxABC, cnxE, cnxG and cnxH. Here we report the existence of a sixth locus, designated cnxj which might be involved in the regular of cofactor levels. When grown in the presence, but not in the absence, of tungstate or methylammonium, stains carrying cnxJ1 or cnxJ2 have reduced molybdoenzyme levels as judged both from growth properties and enzyme determinations. A new cryosensitive cnxC − allele is also reported. Its phenotype at 37 °C (but not 25 °C) shows some silmiarities to that of the two cnxJ − alleles. A structural role for the cnxC (or cnxABC) product in the coafctor is tentatilvey suggested.
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Expression of Streptococcus mutans Aspartate-Semialdehyde Dehydrogenase Gene Cloned into Plasmid pBR322
More LessStreptococcus mutans chromosomal DNA cloned into the vector plasmid pBR322 in Escherichia coli is able to complement the metabolic defect of an aspartate-semialdehyde dehydrogenase (EC 1.2.1.11) gene (asd) deletion in the host strain. We constructed two Asd+ recombinant plasmids, pYA570 and pYA571, containing 4·7 and 4·5 kilobases, respectively, of S. mutans chromosomal DNA inserted into the HindIII restriction endonuclease site of pBR322 in the same orientation. The S. mutans UAB62 Asd+ DNA did not hybridize with E. coli DNA which contained an intact asd gene, but did hybridize with S. mutans UAB62 chromosomal DNA. Derivative Asd+ plasmids were then constructed from pYA570. One, pYA574, had a 4·5 kilobase S. mutans insert DNA in the opposite direction from pYA570. In another, pYA575, the S. mutans insert DNA was reduced in size to 1·3 kilobases. It was seen that the orientation of the S. mutans DNA fragment inserted into the promoter region of the pBR322 tetracycline resistance (Tcr) gene affected expression of Tcr. Orientation of the S. mutans insert also affected the stability of the plasmid in certain E. coli strains. Restriction maps for pYA570, pYA571, pYA574 and pYA575 using the endonucleases EcoRI, BamHI, HindIII, PstI and SalI were determined. Asd+ plasmid-directed protein synthesis was studied in E. coli minicells. The plasmids pYA570, pYA574 and pYA575 each produced large amounts of a protein, with a monomeric molecular weight of about 45000, that was distinct from both pBR322 and E. coli specified protein; this protein is the S. mutans asd gene product. Smaller derivatives of recombinant plasmid pYA575 that were Asd− allowed the location of the S. mutans asd gene promoter and the direction of transcription to be determined.
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- Pathogenicity And Medical Microbiology
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Effect of Anti-pilus Antisera on Virulence of Variants of Neisseria gonorrhoeae for Cultured Epithelial Cells
More LessVariants of Neisseria gonorrhoeae P9 possessing α, γ or δ pili were shown to vary in their toxicity and virulence for human epithelial cells. Studies with antisera raised against purified pili showed that attachment and virulence were reduced to a significant degree in the presence of antisera to homologous pili. Heterologous antisera, while capable of agglutinating whole organisms, were largely ineffective in reducing attachment and cytotoxicity. Using an enzyme-linked immunosorbent assay (ELISA) system, the cross-reactivity between pili and heterologous antisera was estimated to be no more than 10–20%.
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- Physiology And Growth
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Influence of Low Oxygen Concentration on Derepression of Nitrogenase in Klebsiella pneumoniae
More LessEffects of oxygen upon derepression of nitrogenase were studied in Klebsiella pneumoniae, using oxyleghaemoglobin to supply and monitor very low dissolved O2 concentrations in a steady-state system. Expression of the nifH gene was studied by using a nifH::lac fusion strain, which also carried the Nif+ plasmid pRD1 so that the production of active nitrogenase could also be monitored. When compared with anaerobic treatments, very low concentrations of dissolved O2 inhibited derepression of both nifH::lac and pRD1 nif. Fifty percent inhibition of derepression occurred at 0·1 μm-O2. The apparent K S of the dominant terminal oxidase was 0·08 m-O2. These results suggest that there is a close relationship between the terminal respiratory system of these bacteria and the repression of nitrogenase by O2.
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Induction and Differentiation of Heterocysts in the Filamentous Cyanobacterium Cylindrospermum licheniforme
More LessThe fragmentation of Cylindrospermum licheniforme filaments resulted in the induction of a synchronous round of heterocyst differentiation. Young heterocysts (proheterocysts) appeared 12 to 15 h after fragmentation, and 12 to 15% of the cells became heterocysts within 24 h. NH4Cl or NaNO3 prevented the formation of new heterocysts, while differentiation was stimulated twofold by the absence of atmospheric N2. The sequence of appearance of heterocyst-specific characteristics was observed following filament fragmentation. Nitrogenase activity increased rapidly between 13 and 26 h, paralleling the increase in heterocyst frequency. Glycolipids unique to the heterocyst envelope were also synthesized between 13 and 26 h, and activities of 6-phosphogluconate dehydrogenase and glucose-6-phosphate dehydrogenase increased after 10 h and 90 h respectively. Aged medium induced sporulation in intact filaments within 1 d. but sporulation could occur no earlier than 2 d after filament fragmentation, indicating that the induction of sporulation requires the presence of mature (but not necessarily functional) heterocysts.
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The Role of Surface Stress in the Morphology of Microbes
More LessThe shapes of many prokaryotes can be understood by the assumption that the cell wall expands in response to tension created by the osmotically derived hydrostatic pressure. Different organisms have different shapes because wall growth takes place in different regions. A previous paper ( Koch et al., 1981a ) considered the simplest case of prokaryotic growth, i.e. that of Streptococcus faecium. In the present paper, an elaboration of this theory is applied to two further cases - the more perfectly spherical cocci and the rod-shaped bacteria. These cases are more complex mathematically, because growth over a considerable fraction of the surface must be considered. Such diffuse growth cannot be treated analytically, but can be simulated on a computer or handled by geometric arguments.
The spherical form of the cocci may result from either diffuse growth over their entire external surface, or from zonal growth in which the addition of new material only occurs in the immediate vicinity of the splitting septum. In the zonal model, it must be assumed that the least amount of previously laid down septal peptidoglycan consistent with wall growth is reworked in the formation of the new external wall. For Gram-positive rods, where the body of the rod is truly cylindrical, three kinds of growth zones are required: (1) the inward edge of the ingrowing septum, (2) the junction of septum and nascent pole, and (3) the cylindrical walls. Two modes for cylindrical elongation are possible: (a) new wall is added in one or a few narrow annular zones, or (b) new wall material is added continuously all over the innermost surface and the outer layer is degraded. It is shown that the latter case applies to Bacillus subtilis.
Also summarized in this paper are results, developed in more detail elsewhere, concerning the morphology of fusiform bacteria, Gram-negative rods and the hyphal tips of fungi.
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The Shape of the Hyphal Tips of Fungi
More LessA growing hyphal tip is analogous to a molten glass bubble blown under special conditions. These conditions are that the pressure is constant throughout the tip and that the surface tension is very low at the apex and increases towards infinity with distance from the tip. The biological correlate for low surface tension at the apex of the hypha is that enzymic activity and rate of fusion of vesicles are very high in the immediate vicinity of the apex. A formula is developed to allow the calculation of the rate of synthesis at a point on the tip from its distance from the axis and the slope of the tip at that point.
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Effects of Iodoamphenicol on Ribosome Assembly in Two Strains of Escherichia coli
More LessWhen the growth of Escherichia coli strain 15TP was inhibited by iodoamphenicol, three ‘iodoamphenicol particles’ accumulated with sedimentation coefficients of 25S, 33S and 45S. The 25S and 33S particles differ in sedimentation properties from equivalent ribosome precursor particles detected during pulse-labelling of exponentially growing cells. Inhibition of a mutant, strain 15–28 (defective in ribosome assembly), by iodoamphenicol resulted in the accumulation of 38S iodoamphenicol particles that are different from the particles made by the parent. The results support the contention that assembly of 50S ribosomal subunits by the mutant is altered at an early stage.
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Kinetics of Protein Turnover in Growing Cells of Bacillus megaterium
More LessThe course of protein degradation during growth of a [14C]leucine-labelled population of Bacillus megaterium with a surplus of the non-radioactive amino acid indicated the presence of a labile protein fraction decaying with a half-life of less than 1 h. The half-life of the remaining ‘stable’ fraction was much longer (40 h or more). A nutrient shift-down increased, and a shift-up decreased the relative size of the labile fraction and the rate of degradation of the ‘stable’ fraction. When bacteria were prelabelled in the presence of ethionine, both the size of the labile fraction and the rate of degradation of the ‘stable’ fraction were increased. A shift-up in temperature caused a large increase in the size of the labile fraction while the rate of degradation of ‘stable’ proteins increased only slightly. The rate of degradation of the labile fraction was not changed significantly by any treatment. The results suggest that the main target of regulation of protein turnover by environmental conditions is the relative size of the labile protein fraction.
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Growth of Streptococcus faecalis var. zymogenes on Glycerol: The Effect of Aerobic and Anaerobic Growth in the Presence and Absence of Haematin on Enzyme Synthesis
More LessStreptococcus faecalis var. zymogenes was grown aerobically and anaerobically in the presence and absence of haematin, with glycerol as the carbon and energy source. Aerobic growth was stimulated by the inclusion of haematin in the medium but fumarate had no effect on growth. The bacterium was unable to grow anaerobically on glycerol unless fumarate was present; haematin had no effect on growth. NADH oxidase activity, which catalysed the oxidation of NADH + H+ to form H2O rather than H2O2, was found in the soluble fraction and was induced by aerobic growth but partially repressed when haematin was present in the medium. In contrast, a particulate NADH oxidase, which was sensitive to inhibition by antimycin A and 2-heptyl-4-hydroxyquinoline N-oxide, was induced by aerobic growth in the presence of haematin. NADH peroxidase was massively induced by aerobic growth, whereas more lactate dehydrogenase activity was found in anaerobically grown bacteria. Catalase was formed only during aerobic growth in the presence of haematin.
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Chemical Dissolution of Cellulose Membranes as a Prerequisite for Penetration from Appressoria of Colletotrichum lagenarium
More LessThe relationship between protein synthesis during appressorial formation and the ability of appressoria to form penetration hyphae in nitrocellulose membranes was investigated for the plant pathogenic fungus Colletotrichum lagenarium. Cycloheximide treatment before appressorial pigmentation inhibited the formation both of penetration hyphae and of haloes, the latter resulting from the partial degradation of cellulose membranes; but treatment after appressorial pigmentation did not inhibit halo formation. When spores were transferred to 32 °C before appressoria became pigmented, both pigmentation and penetration were prevented. In the presence of 1 mm-3,4-dihydroxyphenylalanine (DOPA) at 32 °C, pigmentation was restored, but the formation of haloes and penetration hyphae was still prevented. Penetration into cellulose membranes pretreated with cellulase was observed from 20–30 % of appressoria which had been formed in the presence of cycloheximide at 24 °C or in the presence of DOPA at 32 °C. The results suggest that there are two phases of protein synthesis following spore germination, only the first of which is involved in halo formation.
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Autolysis in vitro of the Stipe Cell Wall in Coprinus macrorhizus
More LessCell walls isolated from rapidly elongating stipes of Coprinus macrorhizus basidiocarps lost 55 % of their dry weight during 24 h incubation at 37 °C. Neutral sugars accounted for 73 % of the solubilized products, glucose being the major sugar component. In the carbohydrate fraction solubilized after relatively short periods of autolysis, polymeric (degree of polymerization > 10), dimeric and monomeric components were detected, and the larger components were converted to monosaccharide as the reaction proceeded. Three polysaccharide fractions of the cell wall were highly susceptible to autolytic enzymes, whereas another fraction was not. Chitin appeared to be relatively resistant. Analyses of the cell walls from various stages during stipe elongation revealed a positive relation between the rate of stipe elongation and the initial rate of autolysis, suggesting that the autolytic enzymes are involved in the mechanisms of stipe elongation.
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Some Properties of Glutathione Biosynthesis-deficient Mutants of Escherichia coli B
More LessMutants of Escherichia coli B that contain essentially no detectable glutathione were isolated. These mutants had a very low activity of γ-glutamylcysteine synthetase or glutathione synthetase. No significant differences in growth in minimal medium were observed between the mutants and the parental strain. The mutants lacking γ-glutamylcysteine synthetase activity were more susceptible to toxic compounds than either the parental strain or a glutathione synthetase-deficient strain. The mutants lacking γ-glutamylcysteine synthetase activity were also susceptible to oxygen.
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- Short Communication
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Haemophilus influenzae and Neisseria gonorrhoeae Recognize Different Specificity Determinants in the DNA Uptake Step of Genetic Transformation
More LessCross-transformation and quantitative competition experiments showed that Neisseria gonorrhoeae and Haemophilus influenzae do not interact with each other’s DNA in transformation. These organisms must interact with different recognition sequences during DNA uptake.
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- Taxonomy
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An Electrophoretic Study of Enzymes as a Tool in the Taxonomy of the Dermatophytes
More LessZymogram patterns from 84 strains of dermatophyte fungi were obtained using polyacrylamide gradient gel electrophoresis of total cell protein extracts. The enzymes investigated were α-naphthyl acetate esterase, acid phosphatase, lactate dehydrogenase, malate dehydrogenase, tetrazolium oxidase and catalase. These patterns were used to construct similarity matrices and dendrograms using computerized techniques. The results showed that zymograms allowed some species to be readily recognized despite morphological variation. This was also seen in the dendrograms where, in addition, groupings based on ecological or sexual criteria could be distinguished.
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The Bacillus firmus-Bacillus lentus Complex and pH 7·0 Variants of Some Alkalophilic Strains
More LessVariants capable of growth at pH 7·0 were obtained from 174 alkalophilic strains (optimum pH 9·7) of the genus Bacillus by successive transfer on media with decreasing pH values. Nearly half of the pH 7·0 variants were like strains of the B. firmus-B. lentus complex. The remaining pH 7·0 variants grew at 50 °C and were assigned to two groups closely related to B. lentus.
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- Corrigendum
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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)