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Author: Weiss, Ingrid M. × End date: 2009 × Start date: 2000 × DDC: 570 × Has files: Yes × Type: Text ×

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    Fast and sensitive screening of transparent composite materials using polarized light image processing
    (Saarbrücken : Leibniz-Institut für Neue Materialien, 2009) Weiss, Ingrid M.; Heiland, Birgit
    Composite materials of natural origin have remarkable material properties. In order to mimic the various functions of such materials for technical applications, it is necessary to understand the structure and the mechanisms of their formation, a scientific field which is called structural biology. A milestone in the era of structural biology was the application of the polarized light microscope for investigating biological specimens by W. J. Schmidt in 1924. A recent development in polarization technology is the LC-PolScope (Abrio IM™ Imaging System) that has been developed by R. Oldenbourg and his colleagues during the past 20 years. Like conventional polarization microscopy, it probes the local anisotropy of the specimen’s optical properties, such as birefringence or dichroism. Since there is a close relationship between such properties and molecular order in bulk materials, polarization microscopy can be regarded as a submicroscopic technique. The LC-PolScope is especially suitable for investigating biological materials without the need for using contrasting agents such as fluorescent markers. We demonstrated the applicability of this technique for the fast and sensitive screening of biological composite materials. Implications for the characterization of biomineralization phenomena in a quantitative manner are discussed.
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    The structure of mollusc larval shells formed in the presence of the chitin synthase inhibitor Nikkomycin Z
    (London : BioMed Central, 2007) Weiss, Ingrid M.; Schönitzer, Veronika
    Background Chitin self-assembly provides a dynamic extracellular biomineralization interface. The insoluble matrix of larval shells of the marine bivalve mollusc Mytilus galloprovincialis consists of chitinous material that is distributed and structured in relation to characteristic shell features. Mollusc shell chitin is synthesized via a complex transmembrane chitin synthase with an intracellular myosin motor domain. Results Enzymatic mollusc chitin synthesis was investigated in vivo by using the small-molecule drug NikkomycinZ, a structural analogue to the sugar donor substrate UDP-N-acetyl-D-glucosamine (UDP-GlcNAc). The impact on mollusc shell formation was analyzed by binocular microscopy, polarized light video microscopy in vivo, and scanning electron microscopy data obtained from shell material formed in the presence of NikkomycinZ. The partial inhibition of chitin synthesis in vivo during larval development by NikkomycinZ (5 μM – 10 μM) dramatically alters the structure and thus the functionality of the larval shell at various growth fronts, such as the bivalve hinge and the shell's edges. Conclusion Provided that NikkomycinZ mainly affects chitin synthesis in molluscs, the presented data suggest that the mollusc chitin synthase fulfils an important enzymatic role in the coordinated formation of larval bivalve shells. It can be speculated that chitin synthesis bears the potential to contribute via signal transduction pathways to the implementation of hierarchical patterns into chitin mineral-composites such as prismatic, nacre, and crossed-lamellar shell types.