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Volume 77,
Issue 2,
1973
Volume 77, Issue 2, 1973
- Biochemistry
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Production of Exo-β-N-acetylglucosaminidase by Bacillus subtilis b
More LessSUMMARY: Bacillus subtilis b produces β-N-acetylglucosaminidase both in simple and complex medium during late logarithmic growth. The enzyme is partly associated with the bacteria but does not accumulate within the organism before release. Addition of β-N-acetylglucosaminides causes an increased differential rate of enzyme synthesis and endogenous inducer may be formed by autolysis. Synthesis of β-N-acetylglucosaminidase seems to be regulated by a balance of inductive and repressive effects.
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Hydroxylation of Progesterone by Extracts of Rhizopus nigricans nrrl1477
More LessSUMMARY: Growing cultures of Rhizopus nigricans nrrl1477 hydroxylate progesterone at the 11α-, 17α- and 6β-positions. Hydroxylation at the 11α-position seems to be predominant. At pH 7.5, extracts of this organism catalysed the hydroxylation of progesterone to 11α-hydroxyprogesterone and 11α-hydroxyallopregnane-3,20-dione. Ethylenediamine tetracetate inhibited and 2-mercaptoethanol stimulated this hydroxylation. While hydroxylation of progesterone at the 11α-position was optimal at pH 7.5, hydroxylation at the 17α-position was optimal at pH 6.5. The effect of some compounds and metal salts was studied.
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The Neutral and Alkaline Proteases of Aspergillus nidulans
More LessSUMMARY: When grown on glucose salts medium containing protein as sole nitrogen source, Aspergillus nidulans strain biA1 synthesizes three neutral or alkaline extracellular proteases (α, γ, e) and one protease (β) that is strictly intracellular. The four proteases are individually distinguishable by electrophoresis, inhibitor-sensitivity, substrate-preference and pH optimum tests. When ammonium ion (50 mM) is added to the medium, protease β is synthesized as two precursors (β1 and β2) and synthesis of α, γ and e is repressed. The precursors β1 and β2 can be separated by electrophoresis; they are weakly active at 50 °C and have no detectable activity in a protease assay. Conversion of β1 and β2 to β takes place during storage of mycelial extracts at 4 °C; it is accompanied by the appearance of detectable activity in the protease assay. The intracellular enzyme γ also occurs as an (active) precursor, δ. Conversion of δ to γ takes place both in vivo and in stored mycelial extracts, but does not occur in stored culture filtrates.
A recessive, single-gene mutation (xprC1), results in simultaneous loss of all extracellular proteases but xprC1 strains grow and differentiate normally on medium containing non-protein nitrogen. Since the extracellular proteases are absent, both in xprC1, and in biA1 when grown in the presence of ammonium, it is concluded that they are not required for normal growth and differentiation. Also as xprC1 does not utilize protein as sole nitrogen or carbon source, protease β is not used in vivo to hydrolyse exogenous protein.
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- Development And Structure
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Ultrastructure of the Intermediate Stages in the Reverting L-phase Organisms of Staphylococcus aureus and Streptococcus faecalis
More LessSUMMARY: The structure of several developmental stages of the reverting L-phase organisms of Staphylococcus aureus and Streptococcus faecalis are shown. Electron-dense spherules were observed inside the reverting organisms. These spherules could separate from the main organism and develop into walled cocci.
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The Fine Structure of Fusiformis nodosus with Special Reference to the Location of Antigens Associated with Immunogenicity
More LessSUMMARY: In an attempt to locate the antigens associated with protection against foot-rot the fine structure of Fusiformis nodosus and the interaction between the organism and specific antiserum obtained from vaccinated animals were studied.
The high titres of circulating agglutinin associated with immunity were shown to be due to the interaction between antibodies and pili. These observations are discussed in relation to the structure and pathogenicity of other Gram-negative organisms.
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Ultrastructural Changes in the Wall during Germ-tube Formation from Blastospores of Candida albicans
More LessSUMMARY: The wall of a blastospore of Candida albicans is organized in a multilayer structure with amorphous, granular and fibrous components of various electron densities. Striking modifications in this structural pattern occurred when a blastospore was induced to form a germ tube, as shown by fluorescence microscopy of primulin-treated organisms and electron microscopy of thin sections. The essential ‘building’ change was the formation from inside the blastospore wall of an electron-transparent layer in which materials of various shape and dimensions were embedded. This layer grew out through a definite zone of the blastospore wall, thus forming an early germ-tube. Germ-tube emergence from the blastospore was made possible by degradative changes of wall structures overlaying the electron-transparent layer, caused probably by combined mechanical and lytic (enzymatic) actions. However, each component of these structures was resynthe-sized at various moments of germ-tube elongation. Therefore the wall of the germ tube had a stratification comparable to that of a blastospore wall; only quantitative differences in the thickness of the constitutive layers existed between them. Some data suggested that the electron-transparent layer that developed during germ-tube formation was rich in chitin.
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Morphological Variability in Teliospores of Puccinia penniseti
More LessSUMMARY: Pure-line isolates of Puccinia penniseti Zimm. collected from various localities were induced to develop telia by growing infected plants of Pennisetum typhoides Stapf and Hubb. Telia developed not only normal two-celled teliospores but also occasionally one- and three-celled and rarely four- and five-celled teliospores. The shape and size of teliospores varied considerably in one-, two- and three-celled teliospores. Three morphological forms of Puccinia penniseti have been distinguished on the basis of this variability.
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- Ecology
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Characterization of the Substances Causing Deformation of Root Hairs of Trifolium repens when Inoculated with Rhizobium trifolii
B. Solheim and J. RaaSUMMARY: Culture filtrate of Rhizobium trifolii and root media of Trifolium repens inoculated with this bacterium contain at least two factors able to cause deformation of root hairs of T. repens. One has properties of a nucleic acid, the other of either protein or polysaccharide. The deforming substances in culture filtrate are heat-labile whereas those in inoculated root medium are stable.
A heat-stable, root hair-deforming component is formed when culture filtrate is mixed with non-inoculated root medium. The deforming substances in the culture filtrate can be adsorbed to clover roots, and eluted with dilute acetic acid or urea. The role of the substances in the binding of rhizobia to clover roots and in the infection process is discussed.
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Attachment of Bacteria to Sulphur in Extreme Environments
More LessSUMMARY: Sulfolobus attaches to sulphur deposited in acid hot springs by means of pili characterized as follows: (i) generally irregular shape with slight curves and bends; (ii) adhesiveness that enables bacteria to attach to sulphur; (iii) acid-stable, resistant to pH values as low as 2; (iv) heat-stable, resistant to temperatures as high as 75 °C. Sulfolobus attached to sulphur in nature and in culture eroded the sulphur crystal where the bacteria were attached. Sulfolobus undergoes the following two forms of attachment: (i) to sulphur by pili which separate the bacterium from the sulphur crystal and permit lateral movement of bacteria; (ii) to glass slides by firm adhesion of the wall to the surface of the slide. Attachment to sulphur in flowing springs enables Sulfolobus to colonize these low pH (2 to 3) high temperature (70 to 75 °C) habitats.
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- Genetics And Molecular Biology
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R Factors from Proteus morganii
More LessSUMMARY: Twenty-eight R factors transmissible to Escherichia coli K12 were derived from 178 naturally occurring strains of Proteus morganii and evidence was found of non-transmissible resistance plasmids in some strains. Nine plasmids were assigned to group N; one P. morganii strain carried two N plasmids which were incompatible in reference strains of E. coli or P. morganii. Six fi + R factors of group FII were found. One was unique among F-like plasmids in conferring hspII restriction. Entry exclusion by these R factors had a specificity distinct from that of FII plasmids previously described. Three R factors of compatibility group FI were the first recognized plasmids of this group with repressed pilus synthesis. Two fi + R factors incompatible with R6K (and with this plasmid constituting group X) were identified, as were one plasmid of group P and an R factor compatible with plasmids of all groups so far described and therefore assigned to a new group (M). Similarities and differences between the R factor sets of P. morganii and P. rettgeri are discussed.
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The Prophage Behaviour in Crosses between Lysogenic and Non-lysogenic derivatives of Streptomyces coelicolor A3(2)
More LessSUMMARY: The prophage ϕC31 was shown to be a genetic determinant of lysogeny in Streptomyces coelicolor A3(2). In mapping experiments with strains cured and relysogenized with mutant phages the prophage was located on the Streptomyces chromosome.
Allele ratios of non-selected markers for crosses between lysogenic and non-lysogenic derivatives of A3(2) differ strikingly from those of crosses between non-lysogenic parents. It is suggested that these differences are due to the loss of certain recombinant classes containing the complete chromosome of the non-lysogenic parent and a fragment from the lysogenic one, as a result of zygotic induction.
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β-Glactosidase Activity and Lactose Utilization in Aspergillus nidulans
More LessSUMMARY: When mycelia of Aspergillus nidulans are grown with lactose or galactose as the carbon source, β-galactosidase activity is induced at least 30-fold. The effect of growth conditions on the formation of the activity was investigated.
The enzyme has been partially characterized: two proteins with molecular weights near 120000 and 450000 have β-galactosidase activity; present evidence suggests that these are different aggregates of the same polypeptide.
A mutant, lac150, is described which grows poorly on lactose and lacks β-galactosidase activity. These two characters are determined by two unlinked genes and independently expressed. This demonstrates the existence of an alternative (and unknown) mode of lactose utilization. Although β-galactosidase activity is not required for mycelial growth on lactose, it is essential for germination of conidia with lactose as the sole carbon source.
Mutants unable to form β-galactosidase activity fall into three genetic groups designated bgaA, B and C. All these mutants grow normally with lactose as sole carbon source. One mutant at the bgaA locus forms a heat-labile β-galactosidase and is presumably a structural gene lesion.
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Plasmid-determined H2S Character in Escherichia coli and its Relation to Plasmid-carried Raffinose Fermentation and Tetracycline Resistance Characters
IDA Ørskov and F. ØrskovSUMMARY: The transmission of the ability to produce hydrogen sulphide was demonstrated in 11 out of 32 H2S-positive Escherichia coli strains collected during the years 1950 to 1971 at the International Escherichia Centre (WHO) in Copenhagen. The ability to ferment raffinose was co-transferred in some cases but not in others. Those of the 11 strains which were resistant to tetracycline also transmitted that determinant.
Three strains carrying the H2S, raffinose and tetracycline resistance characters were examined especially as regards characterization of the transfer factors. It was suggested that one strain contained two compatible fi - transfer factors, one carrying the H2S and raffinose markers, and the other the resistance determinant. In the second strain, an fi - factor transferred the resistance to tetracycline and an fi + F-like factor was responsible for transfer of the H2S-raffinose markers. The third strain harboured two compatible fi + F-like factors, one transferring the H2S and raffinose markers and the other the tetracycline resistance. In one case, only the raffinose character was transferred, and the factor responsible for that transfer was incompatible with the factor carrying the resistance determinant. It was thus inferred that in this case the raffinose character had been substituted for the resistance determinant on the factor that normally transfers this latter character.
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Transformation in a Nutritionally Deficient Mutant of Candida pseudotropicalis
More LessSUMMARY: Data from two experiments indicated that transformation occurred in Candida pseudotropicalis in the conversion of lactose-negative to lactose-positive cells. When the DNA from prototrophic cells was mixed in media with auxotrophic cells approximately 0.1% of the recipient cells were transformed to prototrophs.
Transformation activity of the donor DNA was found to diminish with heat, DNase or 2-deoxyglucose. The frequencies of transformation obtained in this study compare with those observed in other fungi and some bacteria.
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- Physiology And Growth
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The Effect of Iron Deficiency on Respiration and Energy-coupling in Escherichia coli
More LessSUMMARY: Growth and respiration were affected when iron became limiting in batch cultures of Escherichia coli growing in succinate medium. Decrease occurred in the efficiency with which succinate was converted to bacterial mass, in the respiratory-control ratio, in the extent of stimulation of respiration by silver ions, and in the levels of non-haem iron, cytochrome b 1, and NADH and succinate oxidase activities. On addition of ferric citrate to the iron-limited cultures the above components returned at different rates to the levels found in iron-sufficient bacteria. The efficiency of conversion of succinate to bacterial mass, the respiratory-control ratio, and the concentration of non-haem iron recovered more rapidly than did the level of cytochrome b 1 and the oxidase activities. It is postulated that non-haem iron is involved in respiratory chain-linked energy production.
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Bacteriocinogenic Activity in the Genus Cellvibrio
G. Halliwell and C. SweetSUMMARY: The production and characteristics of a new bacteriocin, cellvibriocin, are described. Of ten known strains of Cellvibrio examined six were cellvibriocino-genic. Cellvibriocin produced by Cellvibrio sp. 9916 appeared most specific on most media and was studied in detail. It was thermolabile, unaffected by deoxy-ribonuclease, ribonuclease, lysozyme and catalase but completely inactivated by proteases and protein denaturants such as chloroform, acetone and ethanol. Although not readily detectable nor inducible in liquid culture cellvibriocin was induced on solid (agar) media by ultraviolet light; it was not extractable from agar grown cultures by buffer solutions or by freeze-thawing, or from liquid grown cultures lysed with ethylene diaminotetraacetic acid and lysozyme or from cultures disintegrated by ultrasonication, in a Hughes's press, with butanol or with alumina.
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Osmotic Lysis of Sphaeroplasts from Saccharomyces cerevisiae Grown Anaerobically in Media Containing Different Unsaturated Fatty Acids
More LessSUMMARY: Saccharomyces cerevisiae NCYC 366 was grown anaerobically under conditions that induce a requirement for a sterol and an unsaturated fatty acid. In media containing ergosterol and either oleic acid, linoleic or γ-linolenic acid, organisms grew at about the same rate, although the duration of the lag phase of growth was extended as the degree of unsaturation in the exogenous fatty acid was increased. Organisms grown in each of the three media did not differ in their contents of total lipids or total phospholipids. Between 54 and 65% of the fatty-acid residues in lipids extracted from organisms were the same as the fatty acid supplied in the medium. Organisms grown in linoleic acid-containing medium were less susceptible to sphaeroplast formation, by digestion of the wall with a basidiomycete glucanase, than were organisms grown in the presence of oleic acid. Sphaeroplasts could be obtained from organisms grown in the presence of linolenic acid if spermine was included in the glucanase digest. Sphaeroplasts formed in the presence of spermine from organisms grown in oleic acid-containing medium were less susceptible to osmotic lysis than sphaeroplasts formed from these organisms in the absence of spermine. The effect of spermine was less pronounced with organisms grown in media containing linoleic acid. The inclusion of spermine in the hypotonic solutions of sorbitol did not affect the kinetics of lysis of sphaeroplasts from organisms grown in medium containing oleic acid or linoleic acid.
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Determination of Mean Cell Size of Tetrahymena in Growing Cultures
More LessSUMMARY: The changes in volume, measured by a Coulter particle counter (the ‘electronic volume‘), when suspensions of Tetrahymena are diluted with aqueous electrolyte have been examined kinetically. The diluting solution can have an optimal colligative concentration in which there is initially no change of the measurement; in suboptimal concentration there is initial increase followed by a decrease to a value somewhat less than that prevailing at the moment of dilution (95%), whereas in superoptimal concentrations there is initial decrease followed by an increase. If the initial decrease is severe the subsequent increase restores the value to only 80% of the original. The measurements of electronic volume, and of its changes, reflect the corresponding mean cell volume, and changes of it, estimated by photographic methods. The changes can be accounted for by changes of balance between the elasticity of the cell walls and the osmotic pressure across the walls.
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Factors Influencing the Germination of Basidiospores of Coprinus radiatus
More LessSUMMARY: Constitutional dormancy is demonstrated for basidiospores of Coprinus radiatus. Germination can be induced by heat and certain chemicals. Heating spores to 45 °C for 4 h results in 23% germination and treatment with a variety of chemicals yields about 3%. Germination in spores which are first heated and subsequently treated with chemicals is either similar to that in heated spores (23%) or slightly higher (33%), while spores which are heated in the presence of chemical show germination percentages up to 88%.
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Effect of Light on Carotenoid and Riboflavin Production by the Fungus Cephalosporium diospyri
More LessSUMMARY: Carotenoids were produced in the mycelial form of Cephalosporium diospyri only after exposure to light of wavelength < 500 nm, and production occurred in three stages. The initial photoinduction required light and was temperature-independent. Both subsequent dark stages, consisting of a lag period and of actual synthesis of carotenoids, were temperature-dependent. All steps had an absolute requirement for oxygen. Filtrates from dark-grown cultures contained ribo-flavin, while lumichrome was present in filtrates from light-grown cultures. Intracellular riboflavin levels were the same in both. Concentrations of diphenyl-amine which inhibited carotenogensis in light-grown cultures also inhibited extracellular production of riboflavin by dark-grown organisms. Several compounds with known photomimetic properties were tested on dark-grown mycelia, but pigmentation was induced only in plate cultures containing p-hydroxymercuri-benzoate. These pigments had the appearance of carotenoids, but have not been chemically characterized.
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