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Optimization of a Method for the Isolation of Chloroplasts from Fresh Plant Material for the Development of a Bioassay Test for the Determination of Pesticides in Water

Bio-assays are increasingly used in supplement to classical analyses to determine the effect of contamination of waters with herbicides, some of which have been shown to be able to determine herbicides within the limits in compliance with EC-ordonance for drinking water. Preliminary work carried out at the University of Bonn has demonstrated that contamination of different water systems can be identified using inhibition of the light dependent production of oxygen by chloroplasts. Further experiments at IRMM have shown a potential to transfer membrane systems of chloroplasts into stable powder that can be used to carry out such bio-assays. Results: A method has been developed tor the isolation and breakage ot chloroplasts that allow freeze drying of the thylakoid membranes. The photosynthetic activity of the lyophilized material was maintained to 86 - 95 per cent. This powder can be stored for over five month without loss of activity.

Optimierung und Validierung von Biotests fuer Herbizide

Im Vorgaengerprojekt wurden Biotests entwickelt, mit denen phytotoxische (herbizidale) Wirkungen angezeigt und quantifiziert werden koennen. Dazu dienen aquatische Mikroalgen (iW Scenedesmus acutus) und zellfreie Systeme. Die Tests sollen weiter optimiert werden, insbesondere was Wirkungen von mehreren in der Probe vorhandenen Substanzen betrifft (antagonistische und/oder synergistische Wirkungen von Herbiziden mit verschiedenen Wirkorten). In der zweiten Antragsphase sollen sodann die geeignetsten Testsysteme validiert werden mit Freiwasserproben aus belasteten Zufluessen des Bodensees.

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