Sigrun Machemer-Röhnisch

Learn More
The locomotion of Loxodes as controlled by the natural gravity vector was investigated employing a mass-cell approach. Samples of cells were incubated for 4 hours in a 1.6 mm deep well (41 × 85 mm) filled with defined experimental solution. Their gliding locomotion on surfaces inclined between 0° and 90° was recorded by videocamera. Steady gliding rates(More)
1. We have investigated a physiological component of the gravitaxis of Paramecium using established mechanisms of ciliate mechanosensitivity. The horizontal, up and down swimming rates of cells, and the sedimentation of immobilized specimens were determined. Weak DC voltage gradients were applied to predetermine the Paramecium swimming direction. 2. An(More)
The kinetics of gravitaxis and gravikinesis in Paramecium caudatum were investigated by employing (1) step transitions from normal gravity (1 g) to weightlessness (microgravity) and (2) turns of the experimental chambers from the horizontal to the vertical position at 1 g. The transition to microgravity left existing cell orientations unchanged. Relaxation(More)
Equilibrated Paramecium caudatum cells exposed to a constant DC gradient reorient with their depolarized anterior ends toward the cathode (galvanotaxis). Voltage gradients were applied to cells swimming either horizontally or vertically. Their velocity and orientation were recorded and compared to unstimulated cells. The DC field increased the horizontal(More)
We investigated the autotrophic flagellate Euglena gracilis for gravity-induced modulation of the speed of swimming as previously documented for larger protozoan cells. Methods of video-tracking of swimming and sedimenting cells under 1 g and hypergravity up to 2 g, and computer-assisted data processing were applied. The vertical and horizontal swimming(More)
In the statocystoid-bearing, flat ciliate Loxodes, the peculiar steady locomotion on submersed substrates (called “gliding”) was investigated between 1 g and 5.4 g under controlled environmental conditions in a centrifuge microscope. Videorecordings of the movements of large cell populations were processed with an automated analysis procedure. At 1 g,(More)
Effects of the density of the external medium on gravireception in Loxodes striatus were investigated using Percoll solutions. With increasing density, the swimming rates changed from prevailing in the downward direction to prevailing in the upward direction. A cellular density of 1.036 g cm−3 was determined measuring direction and speed of sedimenting(More)
  • 1