The UNISIST reference manual for machine-readable bibliographic descriptions within the context of international exchange formats

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Structure of the cell walls of Bacillus megaterium KM I. Isolation of amidase and of a newly found enzyme of Streptomyces albus G, working on the cell walls of Bacillus megaterium KM and Micrococcus lysodeikticus

La préparation F2B obtenue par fractionnement sur Amberlite du filtrat de culture de Streptomyces albus G a été examinée par électrophorèse de zone en gradient de sucrose. Cinq enzymes ont été mis en évidence dont trois ont été isolés, les deux derniers restant associés. Trois enzymes distincts rendent la caséine non-précipitable par l'acide trichloracétique. Ils semblent dépourvus d'action sur les parois cellulaires de Bacillus megaterium KM et de Micrococcus lysodeikticus. Le quatrième enzyme est l'amidase, dont la présence dans F2B avait été précédemment démontrée. Cet enzyme hydrolyse les liaisons muraminyle-alanine présentes dans les parois cellulaires bactériennes. L'amidase isolée ne clarifie pas les suspensions des deux types de parois bactériennes étudiés mais exalte l'activité lytique du cinquième enzyme avec lequel elle est associée dans la préparation F2B. Ce cinquième enzyme semble agir comme le lysozyme et la N-ac e thylexosaminidase de Streptomyces au niveau des fragments polysaccharidiques du mucopeptide de base des parois bactériennes. Il s'en distingue par le fait que son action dissolvante sur les parois de Micrococcus lysodeikticus ne s'accompagne pas d'une libération d'oligosaccharides. Il est dénommé: Enzyme "32".The Streptomyces albus G enzymic complex of the F2B preparation has been fractionated by zone electrophoresis in sucrose gradient. Five enzymes have been shown to be present and three of them have been fully separated. Three distinct enzymes make the casein no further precipitable by the trichloroacetic acid. They are likely not to have any action on Bacillus megaterium KM and on Micrococcus lysodeikticus cell walls. A fourth enzyme is the amidase previously studied which splits the muraminyl-alanine linkages present in the bacterial walls. The amidase does not clarify by itself the wall suspensions so far examined but enhances the lytic activity of a fifth enzyme also present in the F2B preparation. As lysozyme and Streptomyces N-acetylhexosaminidase, this fifth enzyme seems to act at the level of the polysaccharide residues of the walls basal mucopeptide but, contrary to those enzymes, its hydrolyzing action does not induce the liberation of free oligosaccharides from Micrococcus lysodeikticus walls. This enzyme will be referred to as Enzyme “32”

Ancient DNA sequence quality is independent of fish bone weight

The field of ancient DNA (aDNA) typically uses between 50 and 200 mg of minimum input weight of bone material for the extraction of DNA from archaeological remains. While laboratory and analysis techniques have focused on improved efficiency of extracting useable sequence data from older and poorer quality remains, bone material input requirements have rarely been critically evaluated. Here, we present the aDNA analysis of 121 size-constrained Atlantic herring remains – weighing between <10 and 70 mg – that were individually sequenced to explore the capacity of successful aDNA retrieval from small archaeological remains. We statistically evaluate the relationship between bone weight and several response variables, including library success, endogenous DNA content, and library complexity, i.e., the number of unique molecules that are obtained. Remarkably, we find no relationship between bone weight and library success, levels of endogenous DNA, or library complexity. Our results imply that – at least in the case of fish bone – even minute bones can yield positive results and that the presumed minimum sample size required should be re-evaluated. Archaeological site, instead of bone size, is the primary driver of DNA sequence quality. Our work expands the number of specimens considered suitable for aDNA analyses, and therefore facilitates efforts to minimize the destructive impact of aDNA research and mediate some of the ethical concerns surrounding destructive analysis.publishedVersio