- Volume 17, Issue 2, 1957
Volume 17, Issue 2, 1957
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The Nature and Distribution of Carotenoids in some Blue-Green Alǵae
More LessSUMMARY: Seven blue-green algae, Anabaena cylindrica, A. variabilis, Coccochloris elabens, Cylindrospermum sp., Mastigocladus laminosus, Microcoleus vaginatus and Nostoc sp., synthesize the same three major carotenoids: β -carotene, echinenone and myxoxanthophyll; zeaxanthin is present in small amounts. Lutein could not be detected. β-Carotene represents between 30 and 60% of the total carotenoids present. The carotenoid distribution in blue-green algae and other photosynthetic organisms is discussed.
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The Action of Chemical Disinfectants on Bacteria in Droplets Compared with that in Large Volumes
More LessSummary: Because of adsorption phenomena, copper sulphate solutions containing traces of protein are less toxic to bacteria in droplets than to similar bacteria in large volumes. With dilute phenol solutions the reverse was found. The quantitative results suggest that the non-flagellate organism studied moves with about 25 times the energy of Brownian motion.
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Protein Synthesis in a Species of Thermophilic Bacillus
More LessSummary: Washed suspensions of a newly isolated species of thermophilic bacillus were used to investigate the conditions necessary for protein synthesis, and the effect of temperature on the rate of such synthesis. The maximum rate of incorporation of radioactive glycine into the cell protein occurred in the presence of a complete amino acid mixture and an energy source; a mixture of purines and pyrimidines was markedly stimulatory. These conditions were optimal also for the synthesis of catalase and of the maltozymase enzyme-complex, and were effective in preventing the loss of β-galactosidase and catalase activities which occurred when the cells were suspended in buffer at 55°. The synthesis of these enzymes and the incorporation of glycine showed a temperature optimum approximating to that for growth.
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The Significance of Polyphenolic Metabolites of Apple and Pear in the Host Relations of Venturia inaequalis and Venturia pirina
More LessSummary: Series of apple and pear shoots were inoculated with the scab pathogens Venturia inaequalis and V. pirina and injected with polyphenolic metabolites extracted from apple and pear leaves, and with urea. The translocation and persistence of arbutin in Cox leaves was demonstrated chromatographically. Injection of metabolites of the highly susceptible varieties Cox and Williams back into the same varieties, markedly inhibited the pathogens, which suggests that these potential resistance factors do not occur only in varieties which are scab resistant. Inhibition of infection was most marked on leaves already developing a mature resistance and the injection treatments were most effective when applied near the time of inoculation. Injection of urea increased susceptibility to V. inaequalis, and further results indicated the importance of optimal balance mechanisms between polyphenolic and nitrogenous metabolites. Chlorogenic acid and isochlorogenic acid strongly inhibited both pathogens and there was some indication of synergism between them as resistance factors.
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An Agar-Diffusion Method for Titrating Bacillus anthracis Immunizing Antigen and its Application to a Study of Antigen Production
More LessSummary: An agar-diffusion method is described for the titration of Bacillus anthracis immunizing antigen and antibody. It is a sensitive and simple method that can be used for determining antigen concentrations in culture filtrates and for titrating antisera from animals and humans which have been immunized with the antigen. Marked improvements in yields of antigen in a defined medium and a hydrolysed casein - amino acids (Casamino) medium have been achieved with the aid of this assay method.
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Dose-response Curves of Toxic and Infective Actions of Adenovirus in HeLa Cell Cultures
More LessSUMMARY: Study of the dose-response curves in titrations of adenovirus type 5 in cultures of HeLa cells suggests two different mechanisms of cytopathic effect. A late effect, caused by relatively small virus doses, is considered to be a manifestation of virus infectivity and is in good agreement with the hypothesis of independent action of virus units in the initiation of infection. The early effect, on the other hand, requires large virus doses and is considered to be of a toxic nature. Infective and toxic properties of adenovirus type 5 are distinguished by the greater sensitivity of the latter to inactivation by ultraviolet light.
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Cell-Wall Lytic Enzymes at Sporulation and Spore Germination in Bacillus Species
More LessSUMMARY: When washed sporulating cells of Bacillus cereus were incubated in buffer at 37° in the presence of toluene, a partial autolysis occurred resulting in the freeing of mature and immature spores. The autolysate contained lytic enzymes which attacked vegetative cells and cell-wall preparations, releasing hexosamine- containing peptides of characteristic constitution. The most active enzyme preparations were obtained from sporulating cells incubated for 1–2 hr. in buffer at pH 5·0–6·0. Two water-soluble lytic systems, enzyme V and enzyme S with pH optima near 4·5 and 8·0 respectively, were separated from the autolysate. Enzyme S is probably identical with the lytic system present in spores of B. cereus and other Bacillus species and further observations on this system are described. When non-sporulating cells of B. cereus were incubated under similar conditions no obvious lysis or sporulation occurred and no cell-wall lytic activity could be demonstrated. In growing cultures of Bacillus cereus, considerable amounts of hexosamine-containing peptides were released into the medium during the period between the appearance of intracellular spores and free spores. It is suggested that enzyme V may be mainly concerned with the release of free spores from sporangia and enzyme S with the lytic processes which accompany spore germination.
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