Geniom technology--the benchtop array facility.

Febit AG develops an integrated benchtop instrument for in situ microarrays preparation, hybridization, readout and data analysis.

Physiological characterization of gravitaxis in Euglena gracilis and Astasia longa studied on sounding rocket flights.

Euglena gracilis is a photosynthetic, unicellular flagellate found in eutrophic freshwater habitats. The organisms control their vertical position in the water column using gravi- and phototaxis. Recent experiments demonstrated that negative gravitaxis cannot be explained by passive buoyancy but by an active physiological mechanism. During space experiments, the threshold of gravitaxis was determined to be between 0.08 and 0.12 x g. A strong correlation between the applied acceleration and the intracellular cAMP and Ca2+ was observed. The results support the hypothesis, that the cell body of Euglena, which is denser than the surrounding medium exerts a pressure onto the lower membrane and activates mechanosensitive Ca2+ channels. Changes in the membrane potential and the cAMP concentration are most likely subsequent elements in a signal transduction chain, which results in reorientation strokes of the flagellum.

Automated biomonitoring using real time movement analysis of Euglena gracilis.

An automated biomonitoring system for early warning of pollutants in aquatic environments is described and characterized. The system uses sublethal changes in the movement behavior of the flagellate Euglena gracilis as biological endpoints. The movement is determined by real time image analysis. All parameters describing motility, velocity, orientation, and form of the cells are calculated during measurement, and changes of these parameters are interpreted as effect. By automatic dilution of the water sample, dose-effect relationships can be recorded automatically. A total measurement procedure, including control and sample measurement and filling and rinsing of the system, typically requires 8 min. Measurements with different organic and inorganic toxic compounds were performed and the calculated EC(50) values compared with literature data for the bioluminescence test with Vibrio fischeri. Also, measurements with waste water samples from different industrial plants were performed. The fast response time, the small size, the reliable image analysis system, the calculation of several endpoints, and the automatic measuring procedure are major advantages compared to other biological test systems.

Calcium is involved in the gravitactic orientation in colorless flagellates.

The colorless flagellate Astasia longa shows a pronounced negative gravitaxis. The calcium fluorescence indicator Calcium Crimson was used to detect changes of the intracellular calcium concentration during gravitactical orientation. Astasia shows an increase of the fluorescence after a lag phase of about 10 s, a maximum after about 30 s and a decrease to the basic level within 60 s during gravitactic reorientation. The observed change in fluorescence corresponds to an almost doubling of the initial free calcium concentration. The influence of inhibitors, known to impair gravitaxis, on the calcium concentration of Astasia longa was tested. Addition of caffeine, an inhibitor of phosphodiesterase, increases, while addition of gadolinium, an inhibitor of mechanosensitive ion channels decreases the fluorescence signal. While gravitactic stimulation of caffeine-treated cells resulted in a kinetics of fluorescence intensity changes comparable to control cells the addition of gadolinium inhibited any calcium concentration change. Dynamic fluorescence imaging was used during a sounding rocket experiment (MAXUS 3 campaign). Different accelerations interrupted by microgravity intervals were applied to Astasia cells. The cells show an increase in the calcium signal upon acceleration and a decrease during the microgravity state. The results strongly reemphasize the working model of gravitaxis which is based on the activation of mechano-sensitive ion channels as one of the primary events in signal perception.