Abstract
In the past decades, bioassays and whole-organism bioassay have become important tools not only in compliance testing of industrial chemicals and plant protection products, but also in the monitoring of environmental quality. With few exceptions, such test systems are discontinuous. They require exposure of the biological test material in small units, such as multiwell plates, during prolonged incubation periods, and do not allow online read-outs. It is mostly due to these shortcomings that applications in continuous monitoring of, e.g., drinking or surface water quality are largely missing. We propose the use of pipetting robots that can be used to automatically exchange samples in multiwell plates with fresh samples in a semi-static manner, as a potential solution to overcome these limitations. In this study, we developed a simple and low-cost, versatile pipetting robot constructed partly using open-source hardware that has a small footprint and can be used for online monitoring of water quality by means of an automated whole-organism bioassay. We tested its precision in automated 2-fold dilution series and used it for exposure of zebrafish embryos (Danio rerio)-a common model species in ecotoxicology-to cadmium chloride and permethrin. We found that, compared to conventional static or semi-static exposure scenarios, effects of the two chemicals in zebrafish embryos generally occurred at lower concentrations, and analytically verified that the increased frequency of media exchange resulted in a greater availability of the chemical. In combination with advanced detection systems this custom-made pipetting robot has the potential to become a valuable tool in future monitoring strategies for drinking and surface water.
MeSH terms
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Animals
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Automation, Laboratory* / instrumentation
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Automation, Laboratory* / methods
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Biological Assay* / instrumentation
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Biological Assay* / methods
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Ecotoxicology* / instrumentation
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Ecotoxicology* / methods
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Robotics* / instrumentation
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Robotics* / methods
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Zebrafish / embryology
Grants and funding
The present study was conducted as part of the project W3-Hydro “Water Quality Event Detection for Urban Water Security and Urban Water Management Based on Hydrotoxicological Investigations” within the Joint GermanIsraeli Water Technology Research Program that received funds from the German Federal Ministry of Education and Research (BMBF) and the Ministry of Science, Technology and Space (MOST), Israel. It was supported through the SOLUTIONS project which received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no. 603437. The authors acknowledge the German National Academic Foundation (‘Studienstiftung des deutschen Volkes’) for a personal scholarship granted to MB, who is currently a Banting Fellow of the Natural Sciences and Engineering Research Council of Canada (NSERC) at the University of Saskatchewan. The funder OptiWater provided support in the form of salaries for ES, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section. The authors would like to kindly thank Nikon Instruments Germany and Tecan Deutschland GmbH for their contribution to this study as a partner of the Students Lab "Fascinating Environment" at Aachen Biology and Biotechnology (ABBt). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.