title: Protozoa as model systems for the study of cellular responses to altered gravity conditions.
abstract: The orientation behavior of Paramecium changed in a similar way after transition to conditions of free-fall in a sounding rocket and after transition to conditions of simulated weightlessness on a fast rotating clinostat.  After a period of residual orientation, Paramecium cells distributed themselves randomly 80 s (120 s) after onset of free-fall (simulated weightlessness).  Swimming velocity increased significantly; however, the increase was transient and subsided after 3 min in the rocket experiments, while the velocity remained enhanced even during 2 h of rotation on a fast clinostat.  Trichocysts were present and without morphological changes in Paramecium cells which had been exposed to a rocket flight, as well as to fast or slow rotation on a clinostat.  Regeneration of the oral apparatus of Stentor and morphogenesis of Eufolliculina proceeded normally on the clinostat.  The results demonstrate that the clinostat is a useful tool to simulate the conditions of weightlessness on earth and to detect gravisensitive cellular functions.
authors.affiliation: DLR, Institute for Aerospace Medicine, Köln, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Hemmersbach-Krause
authors.forename: W
authors.initials: W
authors.lastname: Briegleb
authors.lastname: Häder D-P
authors.forename: K
authors.initials: K
authors.lastname: Vogel
authors.forename: S
authors.initials: S
authors.lastname: Klein
authors.forename: M
authors.initials: M
authors.lastname: Mulisch
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000502:physiology; D056890:Eukaryota / Q000166:cytology / Q000502:physiology; D005089:Exocytosis / Q000502:physiology; D006112:Gravitation; D018466:Gravity Sensing / Q000502:physiology*; D018470:Gravity, Altered; D009024:Morphogenesis / Q000502:physiology; D009949:Orientation; D010247:Paramecium / Q000166:cytology* / Q000502:physiology*; D012399:Rotation; D013026:Space Flight; D013550:Swimming / Q000502:physiology; D014893:Weightlessness; D018474:Weightlessness Simulation