Helmut Breitwieser

An automated and high-throughput Photomotor Response platform for chemical screens.

The zebrafish (Danio rerio) is a well-established vertebrate model organism. Its embryos are used extensively in biology and medicine to perform chemical screens to identify drug candidates or to evaluate teratogenicity and embryotoxicity of substances. Behavioral readouts are increasingly used to assess the effects of compounds on the nervous system. Early stage zebrafish show characteristic behavioral features at stages between 30 and 42 hours post fertilization (hpf) when exposed to a short and bright light flash. This so-called Photomotor Response (PMR) is a reaction of the nervous system of the fish and can be used as a marker in screenings for neuroactive chemicals. To probe a broad and diverse chemical space, many different substances have to be tested and repeated observations are necessary to warrant statistical significance of the results. Although PMR-based chemical screens must use a large number of specimens, there is no sophisticated, automated high-throughput platform available which ensures minimal human intervention. Here we report a PMR platform that was developed by combining an improved automatic sample handling with a remotely controllable microscope setup and an image analysis pipeline. Using infrared illumination during automatic sample preparation, we were able to eliminate excess amounts of visible light that could potentially alter the response results. A remotely controlled microscope setup allows us to screen entire 96-well microtiter plates without human presence that could disturb the embryos. The development of custom video analysis software, including single egg detection, enables us to detect variance among treated specimens and extract easy to interpret numerical values representing the PMR motion. By testing several neuroactive compounds we validated the workflow that can be used to analyze more than one thousand zebrafish eggs on a single 96-well plate.

Fluidically Driven Robots with Biologically Inspired Actuators

In this paper different robot applications are presented that are driven by flexible fluidic actuators. These pneumatically driven actuators are biologically inspired. The first robot presented is an eight legged walking machine with 48 compliant joints. Then an auto propulsive flexible endoscope will be presented, followed by a serpent and an elephant trunk.

Fully Automated Pipetting Sorting System for Different Morphological Phenotypes of Zebrafish Embryos

Systems biology methods, such as transcriptomics and metabolomics, require large numbers of small model organisms, such as zebrafish embryos. Manual separation of mutant embryos from wild-type embryos is a tedious and time-consuming task that is prone to errors, especially if there are variable phenotypes of a mutant. Here we describe a zebrafish embryo sorting system with two cameras and image processing based on template-matching algorithms. In order to evaluate the system, zebrafish rx3 mutants that lack eyes due to a patterning defect in brain development were separated from their wild-type siblings. These mutants show glucocorticoid deficiency due to pituitary defects and serve as a model for human secondary adrenal insufficiencies. We show that the variable phenotypes of the mutant embryos can be safely distinguished from phenotypic wild-type zebrafish embryos and sorted from one petri dish into another petri dish or into a 96-well microtiter plate. On average, classification of a zebrafish embryo takes approximately 1 s, with a sensitivity and specificity of 87% to 95%, respectively. Other morphological phenotypes may be classified and sorted using similar techniques.

Beispiele für den Einsatz von Automatisierungstechnik bei der Analyse biologischer Modellorganismen

Zusammenfassung Biologische Modellorganismen wie z. B. die Eier des Zebrafischs müssen für Experimente in der Regel zunächst in Mikrotiterplatten einsortiert werden, damit sie mikroskopiert werden können. Die Auswertung des dabei gewonnenen Bildmaterials erfolgt anschließend, wie die anderen Prozessschritte auch, meist manuell. Aus diesem Grund wurden Systeme zur Automatisierung der verschiedenen Prozessschritte am Institut für Angewandte Informatik entwickelt. Die ausgewählten Beispiele beinhalten das automatische Sortieren von Zebrafischeiern durch einen Roboter ohne die Einwirkung von sichtbarem Licht, die daran anschließende automatisierte Detektion von motorischen Reaktionen der Fischeier auf optische Reize und ein System zur automatisierten Verhaltensbeobachtung adulter Fische.