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Volume 61,
Issue 3,
1970
Volume 61, Issue 3, 1970
- Articles
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Role of Chitinase and Other Lysosomal Enzymes of Coprinus lagopus in the Autolysis of Fruiting Bodies
More LessSurmmaryThe autolysis of mature fruiting bodies of Coprinus lagopus is caused by the degradation of cell walls. This process is accomplished by the action of chitinases which are newly formed shortly before spore release begins. Chitinase activity is localized intracellularly in vacuoles together with other hydrolytic enzymes. It is released into the wall upon cessation of metabolic activity in senescing gills.
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Profiles of Soluble Protein During Sporulation of Bacillus subtilis
More LessSummary: Electrophoresis in polyacrylamide gels of soluble proteins from Bacillus subtilis showed changing patterns of bands during sporulation. Somewhat different patterns were obtained from extracts of three asporogenous mutants exposed to a sporulation medium but the differences did not correlate well with the stages in sporulation at which the mutants were believed to be blocked.
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Lysogenic Conversion of Rhizobium trifolii
More LessSurmmaryRhizobium trifolii strain su297, when lysogenized with phage 7 or its clear-plaque mutant 7cr, underwent lysogenic conversion that resulted in loss of ability to adsorb phages 7 and 7cr and the related phage 8. The same conversion was reflected in changes in the surface of the bacterium by which a somatic antigen, characteristic of the parent strain, was modified and a new, noncrossreacting, antigen produced.
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Invertase and Disulphide Bridges in the Yeast Wall
D. K. Kidby and R. DaviesSurmmaryInvertase released from Saccharomyces fragilis (Jorgensen) by either breakage or thiol treatment exhibited identical electrophoretic characteristics. Evidence was obtained against an indirect chemical effect of breakage on the release of invertase from yeasts. Electron microscopy revealed no obvious differences between walls of S. fragilis and other yeasts. A model is proposed in which invertase is not bonded to the wall but is retained by structures requiring intact S—S linkings.
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Biochemical Studies on Walls Synthesized by Candida utilis Protoplasts
More LessSummary: Protoplasts of Candida utilis obtained by treatment with helicase built a new wall in a liquid medium. The spherical protoplast was converted to a tubular form which later changed to an ellipsoidal yeast. Walls isolated at different stages of regeneration were analysed. Glucan (42 to 48%), mannan (25 to 31%) and protein (8 to 9%) were the main constituents of walls of normal and completely regenerated ellipsoidal forms. Walls of the tubular forms differed markedly by having a high content of chitin (12 to 18%) and of protein (20%); mannose was present only as traces. The glucan content was similar in normal, tubular and ellipsoidal regenerating yeasts. These results demonstrate that some modifications occur in the structural polysaccharides of the yeast wall which can be correlated with morphological changes in the reversion process. The significance of glucose, mannose and acetylglucosamine polymers is discussed in relation to the biosynthesis of regenerated walls.
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The Production of Opacity in Serum by Group A Streptococci and Its Relationship with the Presence of M Antigen
More LessSurmmaryThe ability to produce opacity in horse serum is a characteristic of certain M types of group A streptococci. The types that produce the opacity factor (O factor) are generally those for which it is difficult to produce good anti-M sera. M-positive (M+) and true M-negative (M − ) variants of strains that belong to serotypes in which the serum opacity reaction (s.o.r.) is positive both possess the O factor, but there is a difference in binding of the factor to other cellular components in the two variants. The O factor is closely bound to the wall-membrane fraction of M − cells, whereas in M+ cells it is easily extracted by Lancefield’s method or 1 % sodium deoxycholate.
It is detectable in broth culture supernatants, in the cytoplasm and in the areas surrounding colonies in pour plates of M+ but not of M − cultures.
The O factor is poorly antigenic, but when it is possible to obtain a good antiserum the inhibitory action is type specific. The O factor produced by several M types appears to be inhibited by normal rabbit serum.
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The Fine Structure of a Nuclear Envelope Associated Endosymbiont of Paramecium
More LessSummaryParticles of a newly described endosymbiont of Paramecium, here referred to as epsilon, have a fine structure that is essentially identical to that of Gram-negative bacteria. The symbionts occur only within loculi formed by extension of the outer membrane of the nuclear envelopes.
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Nature and Properties of a Cytolytic Agent Produced by Bacillus subtilis
More LessSurmmaryThe substance responsible for lysis of erythrocytes by cultures of Bacillus subtilis, designated subtilysin, was purified. It contained a peptide of leucine, aspartic acid, glutamic acid and valine and probably a lipid. Subtilysin was activated by Mg2+, Mn2+ and Ca2+. The rate of haemolysis was abruptly increased by chilling the reaction mixture. Haemolysis was inhibited by normal sera; the most inhibitory serum fractions contained α-and β-globulins. Haemolysis was inhibited by low concentrations of phosphatidylcholine, phosphatidylinositol, phosphatidic acid and sphingomyelin. Subtilysin possessed antibiotic properties and lysed protoplasts and spheroplasts derived from several bacterial species; subtilysin was identical with surfactin, a peptidelipid from B. subtilis cultures that inhibits fibrin clot formation. Kakinuma and co-workers found surfactin to be a heptapeptide having an n-terminal glutamic acid in amide linkage with the carboxyl group of 3-hydroxy-13-methyl-tetradecanoic acid. Surfactin (subtilysin) possesses some properties in common with two other cytolytic agents of bacterial origin, namely, staphylococcal η-toxin and streptolysin S.
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The Electron Transport System of Kappa Particles from Paramecium aurelia Stock 51
More LessSurmmaryNADH oxidase activity demonstrated spectrophotometrically in kappa of Paramecium aurelia stock 51, was inhibited by KCN, antimycin A and HOQNO. Using a split beam spectrophotometer we obtained low temperature reduced minus oxidized spectra of whole paramecia and of the mitochondrial fraction of paramecia. Two absorption maxima at 588 and 556 nm. were revealed in addition to the peaks of the known a and c cytochromes. From the reduced minus oxidized difference spectrum, the carbon monoxide difference spectrum and other studies, we concluded that kappa has a cytochrome system very different from that of its host but very much like that of bacteria in the families of Brucellaceae and Enterobacteriaceae. The slight contamination in the preparations could not be responsible for the spectra obtained. These findings strongly support the recent belief that kappas and other symbionts in P. aurelia are procaryotic in nature and origin.
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Methods for the Study of Nuclear and Cytoplasmic Variation in Respiratory Activity of Neurospora crassa, and the Discovery of Three New Genes
More LessSUMMARY
Three methods of detecting respiratory variation in Neurospora crassa have been investigated. They involved the addition of dyes (pontamine sky blue and eosin yellowish) tellurite or tetrazolium to a complete medium containing ethionine. The latter prevented conidiation and enabled the colours of the colonies to be seen clearly. These methods were used to distinguish nuclear and cytoplasmic cytochrome mutants (cyt-i, cyt-2, mi-i, mi-3, SG-3 and SG) from wild-type colonies on the basis of colour. Tetrazolium violet (2-5-diphenyl-3-(i-napthyl)-tetrazolium chloride) incorporated into modified Nagai medium with ethionine is recommended for distinguishing cytoplasmic mutants of Neurospora from wild-type. Certain other nuclear mutants were also distinguishable from wild-type in some of these tests. These were ac-i, ac-2, acr-3, ad-4, leu-5, nit-i, oxD-i. Thirty-two wild-type strains in reciprocal crosses were tested on these media to find whether these tests would distinguish any nuclear or cytoplasmic variation. No new cytoplasmic variants were found. Three new nuclear genes, Bm (mauve on dye media), Tet-R (ability to reduce tetrazolium) and sir (suppressor of mi-3) are described and have been mapped. All three loci were linked to the mating type locus on chromosome 1. Tet-R was found in only certain wild-type strains of mating type a (e.g. 74-or8-ia), and Tet-W (unable to reduce tetrazolium) was found in all wild-type strains of mating type A (e.g. 74-or23-i A) and certain wild-types of mating type a;f, a suppressor of mi-i, also suppressed SG-3 and SG, but not mi-3; su− suppressed mi-3, but none of the other cytoplasmic mutants.
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Mutants of Streptomyces coelicolor Defective in Sporulation
More LessSummary: Sporulation-defective mutants were isolated on the basis of altered colonial coloration. The mutants were classified into a number of morphological classes by means of phase-contrast and electron microscopy. Some mutants lacking sporulation septa, the special septa that lead to spore delimitation and separation in the wild-type, or differing from the wild-type in the spacing of such septa, were subjected to genetic analysis. This has so far revealed two, and possibly three, genes concerned with the formation and spacing of sporulation septa.
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Pisatin Production by Tissue Cultures of Pisum sativum L
More LessSurmmaryCallus tissues of Pisum sativum produced the phytoalexin pisatin when grown in axenic culture. Coconut milk, which was in the culture media, induced pisatin formation in pea leaf discs. Cultures which had been established for over 18 months showed a marked reduction in the ability to produce pisatin. Pisatin inhibited the growth of pea callus at low concentrations (5 to 10 μg./ml.), and may control callus tissue initiation and cellular necrosis during host-fungus interactions.
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