- Volume 77, Issue 1, 1973
Volume 77, Issue 1, 1973
- Obituary
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- Biochemistry
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Purification and Properties of an Extracellular Polysaccharide Containing Amino Sugars Formed by Bacillus cereus
More LessSUMMARY: A water-soluble polysaccharide containing amino sugars was isolated from the culture fluid of Bacillus cereus by alcohol precipitation and purified by chromato-graphy on DEAE-cellulose followed by gel filtration. It was composed of N-acetylglucosamine, N-acetylgalactosamine and D-glucose, in the molar ratio 5:3:1. N-Acetylgalactosamine was found at the reducing end. The polymer gave a single peak in the analytical ultracentrifuge, corresponding to a mol. wt of 35000.
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An Esterase Zymogram of Escherichia coli
More LessSUMMARY: The intracellular esterases of 25 strains of Escherichia coli, growing exponentially on a minimal medium, were analysed by the acrylamide-agarose zymogram technique.
Five kinds of esterase bands were defined: three major bands (A, B and C) and two minor ones. The A and B esterase bands hydrolysed α-naphthyl, β-naphythl and indoxyl acetates; they were inhibited by di-iso-fluoropropyl phosphate (DFP). Esterase band B also hydrolysed the α- and β-naphthyl butyrates and was stable at 60°C. Esterase band C hydrolysed only β-naphthyl acetate and it resisted DFP. The A, B and C esterase bands showed variations in electrophoretic mobility which seemed to indicate an intraspecific differentiation of molecular structures of the esterase that could have arisen during microbial evolution.
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Urease and ATP: Urea Amidolyase Activity in Unicellular Algae
More LessSUMMARY: Urease or ATP: urea amidolyase activity was detected in extracts of unicellular algae (representing two phyla and five classes) grown with urea as sole source of nitrogen. All the algae examined that are unequivocally classified as Chloro-phyceae, contained ATP:urea amidolyase but no urease. All the other algae contained urease but no ATP: urea amidolyase.
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- Development And Structure
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The Nature of the Electron-transparent Zone that Surrounds Mycobacterium lepraemurium inside Host Cells
More LessSUMMARY: Liver and spleen tissue from mice infected 4 to 5 months previously with Mycobacterium lepraemurium has been examined in the electron microscope by negative staining, freeze-etching and ultrathin sectioning. Part or all of the electron-transparent zone seen around sectioned bacteria is composed of parallel fibrils wrapped longitudinally around the bacteria. It was isolated from homogenates of infected livers and spleens using urea density gradients and contained a mycoside of type C, a peptidoglycolipid known to occur in some other species of mycobacteria. The mycoside therefore forms a capsule around the bacterium to protect and insulate it from the host cell and its lysosomes.
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- Genetics And Molecular Biology
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An I Pilus-determining R Factor with Anomalous Compatibility Properties, Mobilizing a Gentamicin-resistance Plasmid
More LessSUMMARY: An R factor complex, JR66, consisted of JR66a, a self-transmissible plasmid conferring resistance to streptomycin and kanamycin and capable of mobilizing JR66b: JR66b was a non-self-transmissible plasmid conferring resistance to gentamicin, streptomycin, tetracycline, chloramphenicol, kanamycin and sulphonamides. It was a member of compatibility group FII. JR66a, which determined I pili, was incompatible with members of two distinct groups, I and B. Plasmids of both these groups were shown to determine I pili.
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Plasmids Determining I Pili Constitute a Compatibility Complex
More LessSUMMARY: Plasmids which determine I pili were subdivided by their compatibility properties. The original examples, R64, R144 and Col Ib-P9, together with others more recently isolated, constituted one group, termed Iα. Another group, Iβ, was compatible with Iα plasmids. The 1β group was represented by some newly observed trimethoprim-resistance factors. A group incompatible with both of these (possibly the ancestral form) was designated Iω. Yet another group, designated Iγ was compatible with all the above plasmids, and with members of all other known compatibility groups. Its exemplar repressed piliation by some, but not all, mutant Iα plasmids derepressed for pilus synthesis. Exclusion was not necessarily correlated with incompatibility.
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Changes in RNA Transcription during Morphogenesis of Arthrobacter crystallopoietes
More LessSUMMARY: Arthrobacter crystallopoietes is a bacterium whose life cycle involves sphere-rod-sphere morphogenesis. The molecular mechanism of such cellular differentiation is unknown. It is not clear whether this is regulated by simple metabolic controls such as feedback inhibition or whether expression of the genome is implicated. The present study involves a comparison of RNAs synthesized throughout the life cycle by using competitive RNA-DNA hybridization. The results show that there are differences in the RNAs synthesized at different times. The RNA appears to fall into two general categories, with some sequences always present and other sequences found only at certain times. Morphogenesis thus involves differential transcription of the genome.
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Mapping the Chromosome of Yersinia pseudotuberculosis by Interrupted Mating
More LessSUMMARY: By interrupting matings at different times, the sequential transfer of selected and unselected markers to recipient bacteria was followed in Yersinia pseudotuberculosis. Under the best mating conditions employed, the earliest marker was transferred within 13 min and the latest within 98 min of impinging mating mixtures on membranes. All tested donor markers appeared in recombinants. A genetic map based on the entry times of markers indicated a single linkage group showing much similarity to that of Escherichia coli. The high frequency donor transferred markers in a clockwise direction, its origin corresponding to a point near 60 min on the E. coli map.
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Transductional Analysis of Non-motile Mutants in Proteus mirabilis
More LessSUMMARY: Twenty-six non-flagellate and two paralysed mutants of Proteus mirabilis strain 13 were investigated by transduction with phage 34.13. Abortive transduction divided fla mutants into eight complementation groups (flaA, B, C, D, E, H, J, K) while the mot mutants formed one group. Intracistronic and non-reciprocal complementation was found in certain complementation groups. With the exception of flaH, which could not be mapped, all fla genes were linked to each other and to the mot gene. A genetic map of fla and mot mutations was constructed. Representatives of the eight fla mutant groups did not elicit flagellar antibodies in rabbits and are probably unable to synthesize flagellin.
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Repair of DNA Damage Produced by Gamma-radiation in Escherichia coli k-12 and a Radiation-sensitive exrA Derivative during Inhibition of Protein Synthesis and Normal DNA Replication by Chloramphenicol
More LessSUMMARY: Exponentially growing Escherichia coli PAM5717 exrA is radiation-sensitive, does not carry out ‘slow’ repair of single-strand DNA breaks and shows substantial DNA degradation after gamma-irradiation. When chloramphenicol is present for 90 min before and after gamma-irradiation, survival is enhanced, DNA degradation is minimal and single-strand DNA breaks are repaired both in PAM5717 exrA and the radiation-resistant parental strain AB1157. Thus, both radiation-resistant and exrA bacteria can repair single-strand breaks in the absence of normal DNA replication. Similar repair was observed in a polA strain suggesting that DNA polymerase I is not involved. Both radiation-resistant and exrA bacteria also show a small amount of gamma-ray stimulated DNA synthesis under these conditions. It is suggested that neither the exrA + gene nor protein synthesis are required for repair of single-strand DNA breaks in the absence of an active DNA replication fork.
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Genetical Studies on the Lipopolysaccharide Structure of Escherichia coli k12
More LessSUMMARY: Escherichia coli K12 strain 2578 was crossed with an E. coli O8 donor. Most of the recombinants selected for the donor his allele were agglutinable by anti-O8 serum. This indicated that the recombinants can synthesize O8-specific units and attach them to the K12 lipopolysaccharide (LPS) core in consequence of the transfer of the his-linked donor rfb cluster determining O8-chain synthesis. In serological tests and phage sensitivity tests most O8-reactive recombinants behaved like typical smooth E. coli O8 strains. This implies that E. coli K12 strain 2578 synthesizes a complete core structure, which is a prerequisite for the formation of smooth recombinants.
Some O8-reactive recombinants displayed a partly rough phenotype. In addition, the typical smooth recombinants segregated partly rough forms. Thus the smooth recombinants appear to be partial diploids for some donor gene(s) involved in LPS synthesis.
Serological tests and phage typing showed that the Escherichia coli K12 core is different from other known core types of Salmonella (Ra) and E. coli (R1–-R3).
The genes (rfa) for the K12 core type were mapped by conjugation at approximately 72 min on the Escherichia coli linkage map.
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The Circular Linkage Map of Streptomyces rimosus
More LessSUMMARY: A circular map of two strains of Streptomyces rimosus was constructed by the analysis of several hundred heteroclones. Segregants from four-point and five-point heteroclones were scored and the markers arranged by the criterion of minimizing the number of quadruple crossovers. Distances between genes were estimated from the analysis of the segregation of pairs of loci, whenever the ratio between the frequency of parental segregants approached the ratio between those of recombinant segregants. The nutritional markers appear to be asymmetrically distributed around the map, the upper arc containing a larger proportion of genes. The arrangement of genes in the upper arc recalls that of S. coelicolor A3(2), with which S. rimosus forms fertile crosses. The ‘empty’ regions known in the S. coelicolor map may be absent in S. rimosus.
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Transfer of a Plasmid between Streptomyces Species
More LessSUMMARY: It has been shown previously that IF strains of Streptomyces coelicolor harbour a plasmid, SCP 1, lacking in UF strains, and that IF strains inhibit aerial mycelium production of UF strains. In the present study, IF strains of S. coelicolor, but not UF strains, were found to inhibit 19 out of 32 wild-type streptomycetes belonging to various species. Some of these presumptive UF wild-types were grown in mixed culture with IF strains of A3(2) and it was found, by a simple visual procedure, that SCP 1 was transferred to one of them, converting it to an IF strain. The rates of loss of SCP 1 from this strain, both spontaneously and after u.v. irradiation, were found to be similar to those from IF strains of A3(2). The plasmid had no detectable effect on recombination within the new strain.
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Non-complementation and Recessiveness as Properties of Missense Suppressor Genes in the Fungus Coprinus
More LessSUMMARY: Mutations in the acu-1 gene which lead to inability to use acetate as sole carbon source have been used to select recessive su+ gene mutations. Of five acu-1 alleles tested, two, designated acu-1–2 and acu-1–4, were suppressible. At least three different su + genes suppressed the acu-1–2 mutation and two su + genes suppressed the acu-1–4 mutation. All five su + mutations are completely allele specific and will only suppress the acu-1 mutation for which they were selected. On a glucose medium, where su + activity is not required for growth, presence of a su + gene depresses the growth rate. These two facts suggest that the su + genes act by causing translation errors. Although individually each su + gene is recessive in a su +/su - heterozygote, any two su + genes in a double heterozygote do not complement. Recessiveness and non-complementation are considered as properties of missense su + genes involving modified tRNA species and interpreted in terms of su + tRNA concentrations.
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- Physiology And Growth
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Solubilization of Molecular Forms of Lysosomal Acid Phosphatase of Solanum tuberosum L. Leaves during Infection by Phytophthora infestans (Mont.) de Bary
More LessSUMMARY: Density-gradient ultracentrifugation of potato-leaf extracts on a Ficoll gradient resolved a fraction containing membrane-bounded particles equilibrating at a density of 1-095 gcm-3. The fraction was heterogeneous by electron microscopy and contained several particle types, some of which had single and double membranes, with diameters between 0.05 μm and 1.0 μm, along with amorphous cytoplasmic material and ER-derived elements. A peak of acid phosphatase activity was associated with the fraction, from which varying amounts of enzyme were released by freezing and thawing, osmotic shock and treatments with Triton X-100, snake venom and phospholipase A. Infection of leaves by Phytophthora infestans resulted in a massive transfer to the supernatant-fluid fraction of one molecular form of acid phosphatase which was particle-bound in the uninfected leaves.
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Nitrate Dependent Anaerobic Acetylene-reduction and Nitrogen-fixation by Soybean Bacteroids
More LessSUMMARY: Bacteroids isolated from nodules produced by one strain of Rhizobium japonicum (CC705) had strong nitrate-reducing activity and reduced C2H2 to C2H4 and N2 to NH3 anaerobically with nitrate. Bacteroids of another strain (CB1809) were much less active nitrate reducers and reduced little C2H2 anaerobically. Nitrite, which accumulated in the medium in anaerobic assays, was an inhibitor of C2H2 reduction in both aerobic and anaerobic conditions. Succinate, at about 25 mM, stimulated both nitrate reduction and C2H2 reduction under aerobic conditions. Glucose stimulated C2H2 reduction up to 120 mM but nitrate reduction was inhibited in the presence of glucose. In terms of electrons transferred, the aerobic pathway appeared to be about 2.5 times more efficient than the anaerobic pathway in supporting nitrogenase activity of CC705 bacteroids.
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Effect of Inhibitors on Zeaxanthin Synthesis in a Flavobacterium
More LessSUMMARY: Several substances have been tested for inhibitory effects on carotenoid biosynthesis in Flavobacterium R1519, an organism which normally produces zeaxanthin (β,β-carotene-3,3ʹ-diol) as essentially its only carotenoid. Diphenylamine, several mixed-function oxidase inhibitors (SKF 525A, SKF 3301A, SKF 7997A3, metopirone base, diphenylpropylacetic acid, piperonyl butoxide), several alkaloids (atropine, brucine, hyoscyamine, pilocarpine, quinidine, quinine, scopolamine, strychnine), some substitued pyridines (pyridine, 3-picoline, 3-ethylpyridine, 5-ethyl-2-methylpyridine) and morpholine showed no specific inhibitory effects. In cultures grown in the presence of CaCl2, β-carotene (10%) and β-cryptoxanthin (10%) partly replaced zeaxanthin. Nicotine specifically inhibited zeaxanthin synthesis. Lycopene (in 5 mM-nicotine) and rubixanthin (in 1 mM-nicotine) accumulated as the new main pigments; [2-14C]mevalonic acid was efficiently incorporated into both. Nicotine thus inhibited the cyclization reaction in carotenoid biosynthesis in Flavobacterium R1519 as in other organisms; in zeaxanthin biosynthesis cyclization appeared to precede hydroxylation. Similar inhibitory effects were produced by (+) and (-) nicotine and by nor-nicotine, but not by the closely related anabasine, myosmine, β-nicotyrine and nor-nicotyrine.
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Respiratory Oscillations and Heat Evolution in Synchronously Dividing Cultures of the Fission Yeast Schizosaccharomyces pombe 972h-
More LessSUMMARY: Large-scale synchronous cultures of the fission yeast Schizosaccharomyces pombe 972h- were prepared by a sedimentation—velocity selection method in a zonal rotor. Oxygen uptake was measured polarographically on samples withdrawn at frequent intervals from the culture vessel. Rates of oxygen uptake, expressed per ml culture, increased exponentially, doubling over each cell cycle, but rose to maxima twice per cycle, once during cell division and once at approximately one-half of the cycle. Oxygen uptake at the maxima was stimulated by carbonyl-cyanide m-chlorophenyl hydrazone; that at the troughs was insensitive to this compound. Oxygen uptake was inhibited at all points in the cycle by antimycin A and cyanide at low concentrations; inhibition by these compounds did not alter the periodicity of the oscillations. Heat evolution increased at a constant rate during two cycles of synchronous growth, but in the presence of carbonyl-cyanide m-chlorophenyl hydrazone, peaks of heat evolution in phase with peaks of oxygen uptake were observed. The discontinuous respiratory activity of mitochondria through the cell cycle is discussed with reference to previous contrasting data, and possible control mechanisms are suggested.
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- Short Communications
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- Taxonomy
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Two New Species of Lactobacillus Isolated from the Bovine Rumen, Lactobacillus ruminis sp.nov. and Lactobacillus vitulinus sp.nov
More LessSUMMARY: Two new anaerobic species of Lactobacillus from the bovine rumen are described. They belong to the subgenus Thermobacterium and contain meso diamino-pimelic acid in the wall peptidoglycan. The species differ from each other in being motile and non-motile, in the type of lactic acid produced and in % base composition of their DNA. They have been named Lactobacillus ruminis and L. vitulinus.
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Sterigmatomyces acheniorum species nova, a Yeast from Strawberries
More LessSUMMARY: A new species of yeast, Sterigmatomyces acheniorum, is described. The strains, isolated from fresh strawberries, differed from other species of Sterigmatomyces in the test substrates they utilized. The strains grew slowly on certain organic substrates on three of which they formed mainly small colonies with a minority of large ones. When subcultured on the same substrates, large colonies gave rise to further large colonies, and small colonies produced mainly small colonies with a minority of large ones.
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Computer Identification of Yeasts of the Genus Saccharomyces
More LessSUMMARY: A punched-card system of identification by computer is described, whereby matching at over 85% with the description of a recognized Saccharomyces species constitutes identification. The system is based on a set of 39 invariable descriptions of species, so defined that no species is related at higher than 85% matching coefficient to any other species.
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Taxonomically Significant Colour Changes in Brevibacterium linens Probably Associated with a Carotenoid-like Pigment
More LessSUMMARY: Ninety-three coryneform bacteria were tested with various acids and bases and on the basis of these tests, five of the strains were identified as Brevibacterium linens. This identification correlated with that made by other methods, thus confirming the suggestion of Grecz & Dack (1961) that B. linens could be identified by certain colour reactions. Further studies indicated that these reactions are probably associated with the presence of a specific carotenoid-like substance located in the bacterial membrane.
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- Corrigendum
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Volumes and issues
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Volume 170 (2024)
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Volume 169 (2023)
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Volume 168 (2022)
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Volume 167 (2021)
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Volume 166 (2020)
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Volume 165 (2019)
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Volume 164 (2018)
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Volume 163 (2017)
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Volume 162 (2016)
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Volume 161 (2015)
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