Endosymbiotic interactions are frequently found in nature, especially in the group of protists. Even though many endosymbioses have been studied in detail, little is known about the mechanistic origins and physiological prerequisites of endosymbiont establishment. A logical step towards the development of endocytobiotic associations is evading digestion and escaping from the host's food vacuoles. Surface properties of bacteria are probably involved in these processes. Therefore, we chemically modified the surface of a transformant strain of Escherichia coli prior to feeding to Tetrahymena pyriformis. N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide allows any substance carrying amino- or carboxyl groups to be bound covalently to the bacterial surface by forming a peptide bond, thus, altering its properties biochemically and biophysically in a predictable manner. The effect of different traits on digestion of T. pyriformis was examined by fluorescence and transmission electron microscopy. The efficiency of digestion differs considerably depending on the coupled substances. Alkaline substances inhibit digestion partially, resulting in incomplete digestion and slightly enhanced escape rates. Increasing hydrophobicity leads to much higher escape frequencies. Both results point to possible mechanisms employed by pathogenic bacteria or potential endosymbionts in evading digestion and transmission to the host's cytoplasm.
Sie sind Studieneinsteiger und suchen nach einem leichten Einstieg in die Laborarbeit? Oder Sie sind Dozent und müssen ein Praktikum vorbereiten?
Dieser Titel bietet Studierenden einen praxisorientierten Einstieg in das praktisch-forschende Arbeiten im Labor. Lehrende finden einen kompakten und praxiserprobten Ratgeber für die perfekte Planung, Organisation und Durchführung ihrer Lehrveranstaltung. So sind beide Seiten bestens vorbereitet für das Grundpraktikum Mikrobiologie. Von der Hochschule für die Hochschule entwickelt und erprobt: Kompaktes Grundlagenwissen zur Mikrobiologie, das den Einstieg spielend leicht macht. So verschwinden Berührungsängste im Grundpraktikum, die Arbeit im Labor macht Spaß und der Prüfung können Sie sorglos entgegensehen.
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