Chitin, a unique structural polysaccharide found in fungi and arthropods, is not produced by vertebrates. Thus, the potential applications of a specific and sensitive assay for chitin are numerous, including the evaluation of the extent of fungal keratitis. Chitin is a homopolymer of beta (1, 4) linked D-N-acetylglucosamine. We have developed a simple and reproducible assay for chitin and applied it to Candida albicans cultures. The assay involves homogenization of the culture and treatment with 21.1 M KOH to remove soluble materials, including proteins. This base treatment also deacetylates the chitin to the glucosamine polymer, chitosan. Chitosan is hydrolyzed by 0.5 M H2SO4 to glucosamine monomers which are then deaminated by the addition of NaNO2 to the acid solution. The resulting 2,5-anhydromannose is reduced by NaB[3H]4 to 1-[3H] 2,5-anhydromannitol. This radiolabelled sugar is isolated by paper chromatography and quantified via liquid scintillation. The sensitivity of this assay is assessed by comparison of colony forming units (CFU's) with a glucosamine standard. A typical run of the assay detects 53.1 CFU/c.p.m., and 356,000 c.p.m. per nanomole of N-acetylglucosamine. The specificity of the assay is very high because of the unique nature of chitin. This method of chitin determination may be a useful alternative method for future investigations involving the study of fungal infections in mammalian tissues.
26Medieval manuscripts, carefully curated and conserved, represent not only an irreplaceable documentary 27 record but also a remarkable reservoir of biological information. Palaeographic and codicological 28 investigation can often locate and date these documents with remarkable precision. The York Gospels 29 (York Minster Ms. Add. 1) is one such codex, one of only a small collection of pre-conquest Gospel 30 books to have survived the Reformation. By extending the non-invasive triboelectric (eraser-based) 31 sampling technique eZooMS, to include the analysis of DNA we report a cost effective and simple-to-use 32 biomolecular sampling technique. We apply this combined methodology to document for the first time a 33 rich palimpsest of biological information contained within the York Gospels, which has accumulated over 34 the 1,000 year lifespan of this cherished object that remains an active participant in the life of York 35Minster. This biological data provides insights into the decisions made in the selection of materials, the 36 construction of the codex and the use history of the object.
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