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Volume 18,
Issue 1,
1958
Volume 18, Issue 1, 1958
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New Proteolytic Enzymes from Clostridium histolyticum Filtrates
More LessSUMMARY: Oakley & Warrack (1950) established the presence of two serologically distinct proteolytic enzymes in Clostridium histolyticum filtrates, a β-toxin digesting native collagen and a cysteine-activated γ-toxin attacking azocoll and other protein substrates.
In the present paper we give evidence of another proteolytic enzyme, not activated by cysteine and serologically different from those previously described. This we designate as δ-toxin. We also indicate the possibility of the presence of a fourth enzyme more stable than the others and active against various synthetic substrates in conjunction with cysteine. This enzyme could not be inhibited by antisera. Furthermore peptidases have been detected and will be described in detail elsewhere.
Some of the differences between these enzyme systems are discussed.
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The Cysteine-Inactivated Proteinase (δ-antigen) of Clostridium histolyticum
More LessSUMMARY: Evidence is provided in support of the view of MacLennan, Mandl & Howes (1958) that some strains of Clostridium histolyticum produce a cysteine- inactivated proteinase—the δ-antigen.
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Seroloǵical Evidence for a Specific Clostridium histolyticum Gelatinase
More LessSUMMARY: Evidence is presented that a specific gelatinolytic enzyme besides collagenase is present in purified Clostridium histolyticum collagenase preparations. This means that collagenase itself need not be able to digest gelatin but it does not exclude the possibility.
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Acytostelium leptosomum: A Unique Cellular Slime Mould with an Acellular Stalk
More LessSUMMARY: A new genus and species of the Acrasieae is described, and for this the binomial Acytostelium leptosomum is applied in recognition of its acellular soro-phores and the diminutive proportions of its sorocarps. This slime mould has been isolated upon four occasions from soil and forest litter collected from deciduous forests within the United States. The vegetative stage of A. leptosomum, as that of the other cellular slime moulds of this Class, consists of the independent growth of myxamoebae which feed upon bacterial cells. The fruiting stage likewise duplicates that of other members of the Acrasieae in its early manifestations; but it differs markedly from these in its terminal phase, i.e. the construction of the mature fructification, or sorocarp. A. leptosomum is at present unique among these slime moulds in its capacity to produce a sorocarp with a non-cellular stalk. The morphogenetic process whereby this is accomplished is not thoroughly understood; nevertheless, a possible explanation of how the stalk may be formed without the expenditure of any cells is offered.
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A Survey of the Production of Pectic Enzymes by Plant Pathoǵenic and other Bacteria
More LessSUMMARY: Sixty-seven cultures of plant pathogenic bacteria, of the genera Agrobacterium, Corynebacterium, Envinia, Pseudomonas and Xanthomonas, and 56 cultures of non-pathogenic bacteria were tested for production of pectic enzymes in culture. γ-Pectinglycosidase was produced by 22 strains of pathogenic bacteria and by 15 non-pathogens. Pectin methyl esterase was produced by a few pathogens: the soft-rot erwinias, X. campestris and one of three strains of X. vasculorum.
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Chromatoǵraphic Examination of the Products of Diǵestion of Pectic Materials by Culture Solutions of Plant Pathoǵenic and other Bacteria
More LessSUMMARY: Solutions containing pectic materials were digested by solutions from cultures of 25 bacteria and examined chromatographically for breakdown products. Galacturonic acid and oligo-uronides were found with soft-rot Erwinia spp., Xan- thomonas campestris, Pseudomonas marginalis, Bacillus polymyxa and Klebsiella aerogenes (galacturonic acid only).
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Intracerebral Infection of Mice with Haemophilus pertussis and Passive Protection by Hyperimmune Rabbit Sera
More LessSUMMARY: The intracerebral invasion in mice by two Haemophilus (Bordetella) pertussis strains, a virulent strain and the strain 18–323 which is very virulent on intracerebral injection, was studied. The LD50 of these strains differed by about a thousand times and the average slopes of the regression lines from which these were calculated differed significantly, (P = 0·04 and P = 0·01). It was found that the number of organisms/mouse brain in infected animals reached a maximum count which was slightly higher for the more virulent strain. The day on which the maximum count was reached depended both on the dose of organisms and the strain used, but occurred always before the seventh day after injection. Further, a slightly lower maximum count was reached as the dose of organisms was decreased. The passive protection by rabbit sera, described as antibacterial and antitoxic sera, against both these strains of pertussis organisms, was studied. It was shown that the protection of neither type of serum was due only to the presence of agglutinin antibodies.
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The Heat Inactivation of Vaccinia Virus
More LessSUMMARY: Heat inactivation curves of vaccinia virus between 50° and 60° indicate that the virus is heterogeneous in its heat sensitivity. The proportion of heat-resistant particles varies inversely with the temperature of exposure. The inactivation of heat-sensitive virus is temperature dependent and seems to be a first-order reaction, while the heat-resistant fraction is inactivated at a constant slow rate unrelated to temperature over the range 50°-60°.
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Activation and Thermostability of Neurospora crassa Tyrosinase
More LessSUMMARY: Tyrosinase in crude cell-free preparations from two strains of Neurospora crassa is markedly activated by gentle heating or by exposure to sodium ion, urea, or certain organic nitrogenous bases. The tyrosinase activity of non-activated extracts increases during assay, whereas activated enzyme displays the ‘reaction inactivation’ kinetics characteristic of many copper oxidases. Activation by Na+ is antagonized by K+ and is readily reversible. Urea activation is also reversible, but the activation due to heating appears to be irreversible. The thermostability of tyrosinase derived from strain TS is increased greatly by Na+ (and less effectively by K+) and the half-life of thermal inactivation at 59° varies between wide limits, depending on the ionic environment. The relatively heat-labile tyrosinase of strain TL shows qualitatively similar behaviour but is quantitatively different with regard to stabilization by Na+ and K+.
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Some Unusual Chrysophyceae Studied in the Electron Microscope
More LessSUMMARY: Three members of the Chrysophyceae are described, the general morphology being studied with the light microscope, but the details of the scale and bristle structure with the electron microscope. Mallomonas ouradion sp.nov. is at present unique in having several movable bristles on each scale. Chrysosphaerella brevispina Korshikov is shown to include C. rodhei Skuja. The peculiar bristle base is elucidated. This is the first record for the genus in Britain. Synura sphagnicola is shown to differ in several respects from other species of Synura. In all three genera, the chromatophore, which has been described as double, is shown to be single but strongly lobed. Replicas of the intact armour of S. echinulata are shown.
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The Bacterial Flora of the Skin of North Sea Cod
More LessSUMMARY: Monthly bacterial counts over a 2-year period provided evidence of a seasonal variation in the numbers of bacteria on the skin of North Sea cod. The variations appeared to be connected with plankton outbursts. The temperature of the sea did not have any great effect, except that the proportion of the population capable of growth at 0° was highest when the sea temperature was at its lowest. The composition of the bacterial flora, determined by isolation of colonies from count plates after incubation at 20°, was: Pseudomonas 44%, Achromobacter 32%, Corynebac- terium 9 %, Flavobacterium 6%, Vibrio 6 %, Micrococcus 1 %, miscellaneous 2 %. When isolations were made after incubation at 0°, strains of the last four genera were less frequently encountered. Some evidence was also obtained of a seasonal variation in the qualitative composition of the flora, Achromobacter and luminous strains appearing more frequently in the winter while Pseudomonas strains increased in the summer. The flora of cod is similar to those of other species of North Sea fish examined by earlier workers; the species of the fish does not appear to play an important role in determining the composition of the skin flora.
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A Study of the Antigenic Specificity of Staphylococcal Coagulase in Relation to Bacteriophage Group
Mary Barber and P. WildySUMMARY: Rabbit antisera were prepared separately against coagulase from staphylococci of each of the three main bacteriophage groups. Neutralization tests showed that each of the three antisera caused considerable delay in the clotting of plasma by coagulase from the autogenous staphylococcus and other strains of the same phage group, but little or no delay in the action of coagulase from strains of other groups. Staphylococci of certain phage types yielded coagulase which was not neutralized by any of the three antisera. Amongst these were types 3 A and 42 E which are usually included in groups II and III, respectively, as well as unclassified types (e.g. 187). Antisera prepared against coagulase from types 3 A and 42 E caused significant neutralization of coagulase of the same type only.
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On the Heterotrophic Growth of Chlorella pyrenoidosa
H. Samejima and J. MyersSUMMARY: Of a large number of possible carbon sources only glucose, galactose, and acetate supported continued growth of Chlorella pyrenoidosa in darkness. Cell synthesis in darkness with nitrate as the nitrogen source proceeded with a carbon assimilation of 45 % for glucose, 37 % for galactose, and 26 % for acetate. The energy efficiency (Rubner coefficient) of cell synthesis from glucose was affected by the nitrogen source and has a maximum value of 58 % with ammonia.
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The Smooth and Rough Somatic Antigens of Pasteurella pseudotuberculosis
More LessSUMMARY: From strains of Pasteurella pseudotuberculosis representing each of the five serological groups and some ‘Rough’ forms, lipopolysaceharides were isolated after disintegration of acetone-dried saline extracted organisms with phenol. The materials appear to carry the specificities on which the serological classification of the species is based; they are relatively poor antigens when isolated but antigenicity can be enhanced by combining with lipoprotein. Analyses show some unusual features, an aldoheptose sugar being present in all of the materials and some of the ‘Smooth’ cell products contain dideoxy sugars; rhamnose is absent. The ‘Rough’ cell products are somewhat similar in composition to the ‘Rough’ somatic polysaccharide of Pasteurella pestis, to which they are also related serologically.
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The Serological Specificities of Pasteurella pseudotuberculosis Somatic Antigens
More LessSUMMARY: The serological specificities of lipopolysaccharides obtained from representatives of each of the five serological groups of Pasteurella pseudotuberculosis have been examined by haemagglutination methods. At concentrations of 500 μg./ml. solutions of the lipopolysaccharides failed to give full sensitization of erythrocytes, but after treatment with alkali full sensitization was obtained at concentrations in the range of 50 to 3 μg./ml. By using antisera prepared in rats by immunization with living P. pseudotuberculosis, the capacity of each ‘Smooth’ lipopolysaccharide to inhibit the agglutination of sensitized erythrocytes by each group antiserum was determined. Absolute group specificity was found by this method. It is considered that the lipopolysaccharides bear the specificity of the somatic antigens on which the serological grouping of the species is based. ‘Smooth’ P. pseudotuberculosis lipopoly-saccharides failed to inhibit the agglutination by P. pestis antisera of erythrocytes sensitized with P. pestis lipopolysaccharide, but inhibition of this system was obtained with lipopolysaccharides of ‘Rough’ P. pseudotuberculosis strains derived from various serological groups. These ‘Rough’ lipopolysaccharides were closely related serologically to one another and to the P. pestis product but were not identical in specificity. It is considered that in Smooth P. pseudotuberculosis strains the ‘Smooth’ somatic antigen does not overlie a ‘Rough’ somatic antigen.
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Nutritional Studies of Cysteineless Mutants of Salmonella typhimurium
More LessSUMMARY: Forty-three separately isolated cyst(e)ineless mutants of Salmonella typhimurium were investigated biochemically. Six main phenotypes were identified, accommodating thirty-nine of the mutants; the remaining four mutants were of intermediate phenotype. The phenotypes are suggested to result from a series of five metabolic blocks in a pathway of cyst(e)ine synthesis in which sulphate can be reduced by two alternative routes, in both of which most of the intermediates are inorganic.
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Investigation of the Genetics of Cysteineless Mutants of Salmonella typhimurium by Transduction
More LessSUMMARY: The genetic investigation of forty-three phenotypically classified cysteineless mutants of Salmonella typhimurium by means of transduction suggests that in forty-one of the mutants, strains of similar phenotype result from mutations occurring at a series of sites which form a closely linked group, presumably situated within a single gene locus. Five such loci have been identified.
Only two of these five presumptive loci are linked, and within these linked loci an unusually high proportion of mutations to auxotrophy appear to result from a chromosomal deficiency. Another locus which is linked to an array of loci controlling tryptophan biosynthesis shows biochemical heterogeneity within the locus.
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Studies on the Cell-Wall Composition and Taxonomy of Actinomycetales and Related Groups
More LessSUMMARY: The cell-wall compositions of 51 strains of Actinomyces, Nocardia, Streptomyces, Micromonospora, Mycobacterium and Propionibacterium have been investigated, together with those of 7 strains of Eumycetes. The cell walls of the actinomycetes were made up of sugars, amino sugars and amino acids (the latter few in number). The general pattern of components was thus identical with that previously found for Gram-positive bacteria. In the fungi, however, the mycelial walls were composed entirely of carbohydrate. These results suggest that the actinomycetes are not related to the fungi but should be classified with the bacteria proper. On the basis of cell-wall composition a classification of the actinomycetes is proposed, to consist of 3 families: Mycobacteriaceae containing the genera Mycobacterium, Nocardia and Corynebacterium; Streptomycetaceae containing Streptomyces and Micromonospora; and Actinomycetaceae with a single genus Actinomyces. The propionibacteria are probably related to Streptomyces. It is also suggested that a separate order Actinomycetales is unnecessary and that the families proposed can more suitably be included in the Eubacteriales.
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Artificial Cultivation of a Red-Pigmented Marine Blue-Green Alga, Phormidium persicinum
More LessSUMMARY: Phormidium persicinum requires light intensities < 300 foot-candles and grows at 10°–33°. The medium developed for P. persicinum is representative of the early types of artificial media having a relatively high concentration of chelator and, necessarily, of trace metals. Other media, varying widely in trace metal: chelator ratios and concentrations allow growth of P. persicinum. Tris 2-amino-2- hydroxymethylpropane-1:3-diol is a suitable pH buffer; its antagonism of potassium utilization was demonstrated and was amply overcome by the addition of 200 mg. K/l. to the medium. Inorganic and organic phosphates were utilized and were required at relatively low concentrations. P. persicinum utilized NO3 − and NH4 + but not atmospheric nitrogen. NaNO3 was the most satisfactory inorganic nitrogen source but the cultures bleached after prolonged growth. Asparagine (0·2–0·8 g./l.) maintained the normal purple pigmentation over a longer period; it served as a non-toxic slowly-utilized reservoir of available N. Vitamin B12 is the only essential vitamin and is needed at a concentration (100 mμg./l.) which is higher than for most algae. All the cobalamins including factor B, but not methionine or deoxy- ribosides, can substitute for vitamin B12. The physiological and ecological resemblances of P. persicinum to red or violet blue-green algae growing in deep water are discussed.
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Lysogenicity and Immunity to Bacillus Phage W
More LessSUMMARY: Cultures of strain W of Bacillus cereus sometimes contained a phage, Wα, which could form plaques on strain W itself. Phage Wα was found to be a virulent mutant of a temperate phage, Wβ, with which strain W was lysogenic. Another non-lysogenizing mutant, Wγ, was also isolated which, unlike α did not form plaques on strain W. The genetic determinants of α, β and γ are probably allelic. Neither phage γ nor phage β formed plaques on bacterial strains lysogenic with β, but these strains were not completely immune, even to the temperate phage. This finding shows that lysogenicity does not invariably confer complete immunity to the carried phage. The colonial appearance of a strain was altered after lysogenization in a way suggesting that the alteration was due to its incomplete immunity to the temperate phage produced during growth.
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