test system stability and natural variability of a lemna gibba l. bioassay测试系统稳定性和自然变化的浮萍属gibba l .生物测定.pdfVIP

Test System Stability and Natural Variability of a Lemna Gibba L. Bioassay 1,2 3 ¨ 1 2,4 Claudia Scherr *, Meinhard Simon , Jorg Spranger , Stephan Baumgartner 1 Research Institute of Organic Agriculture, Frick, Switzerland, 2 Society for Cancer Research, Institute Hiscia, Arlesheim, Switzerland, 3 Institute for Chemistry and Biology of the Marine Environment ICBM, University of Oldenburg, Oldenburg, Germany, 4 Institute of Complementary Medicine KIKOM, University of Bern, Bern, Switzerland Abstract Background: In ecotoxicological and environmental studies Lemna spp. are used as test organisms due to their small size, rapid predominantly vegetative reproduction, easy handling and high sensitivity to various chemicals. However, there is not much information available concerning spatial and temporal stability of experimental set-ups used for Lemna bioassays, though this is essential for interpretation and reliability of results. We therefore investigated stability and natural variability of a Lemna gibba bioassay assessing area-related and frond number-related growth rates under controlled laboratory conditions over about one year. Methology/Principal Findings: Lemna gibba L. was grown in beakers with Steinberg medium for one week. Area-related and frond number-related growth rates (r(area) and r(num)) were determined with a non-destructive image processing system. To assess inter-experimental stability, 35 independent experiments were performed with 10 beakers each in the course of one year. We observed changes in growth rates by a factor of two over time. These did not correlate well with temperature or relative humidity in the growth chamber. In order to assess intra-experimental stability, we anal