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The gravitactic ciliates Paramecium and Loxodes were cultivated for 15 days in space during the IML-2 spacelab mission. At dedicated times their behavioral responses to different accelerations between 10(-3) x g and 1.5 x g were investigated by using a slow rotating centrifuge microscope (NIZEMI). The threshold for gravitaxis of Paramecium was found to be(More)
  • W Briegleb
  • 1992
In 1958 the geneticist H.J. Muller proposed an extension of the principle of the (slow) plant clinostat which --to a certain extent--abolishes g effects on plant growth (geotropism). Muller predicted that a feeling of weightlessness would be experienced by a human being attached to a clinostat platform, the rotation speed of which is enhanced compared to(More)
The acellular slime mold Physarum polycephalum was used to investigate a postulated general gravisensitivity of cells. Physarum was subjected i) to a rotation on the fast-rotating clinostat, which enables the simulation of weightlessness (0 g), and ii) to single horizontal turns of 180 degrees. On the fast-rotating clinostat the response consists of a(More)
Cellular signal processing in multi-, as well as in unicellular organisms, has to rely on fundamentally similar mechanisms. Free-living single cells often use the gravity vector for their spatial orientation (gravitaxis) and show distinct gravisensitivities. In this investigation the gravisensitive giant ameboid cell Physarum polycephalum (Myxomycetes,(More)
A cell culture of Paramecium with a precise negative gravitaxis was exposed to 4 x l0(-6) g during a parabolic flight of a sounding rocket for 6 min. Computer image analysis revealed that without gravity stimulus the individual swimming paths remained straight. In addition, three reactions could be distinguished. For about 30 s, paramecia maintained the(More)
During the 6 min-lasting "free-fall conditions" (4 x 10(-6) g) of the parabolic flight of a sounding rocket Paramecium aurelia cells showed an increase of 7.5 % in their mean swimming velocity. A detailed analysis revealed that the kinetic response was transient: after 3 min the velocity decreased to the speed of the former horizontal swimming at 1 g.(More)
Epidermal growth factor (EGF) induces rapid rounding of A431 human epidermoid carcinoma cells. This process is dependent upon temperature and EGF concentration. To investigate the possible influence of gravity variations on EGF-induced cell rounding of A431 cells, experiments were performed using a fast-rotating clinostat and centrifuge, thereby simulating(More)
Theoretical investigations of the membrane-solution interface predict different effects of gravity on vertically and horizontally oriented planar membranes. Single channel events of gramicidin incorporated into phosphatidylserine planar bilayer membranes were measured in 0.1 M KCl solution, pH 7, at room temperature. The potential difference across the(More)
Cultures of human lymphocytes were exposed to the mitogen concanavalin A in a low-G environment generated by a fast rotating clinostat. DNA-synthesis was determined by incorporation of 3H-thymidine as the parameter for activation, cell ultrastructure was analyzed by electron microscopy, and cell movements were recorded by a cinecamera. The results were(More)