The beating pattern of the flagellum of Euglena gracilis under altered gravity during parabolic flights

• Published in: Journal of plant physiology Vol. 167; no. 1; pp. 41 - 46
• Main Authors: Strauch, S.M., Richter, P., Schuster, M., Häder, D.-P.
• Format: Journal Article
• Language: English
• Published: Munich Elsevier GmbH 2010; Elsevier
• Subjects: Aircraft; Biological and medical sciences; Cell motion; Cell physiology; Euglena gracilis; Euglena gracilis - cytology; Euglena gracilis - physiology; Flagella - physiology; Flagellum; Freshwater; Fundamental and applied biological sciences. Psychology; Gravitaxis; Gravity, Altered; Hypergravity; Microscopy; Movement - physiology; Plant physiology and development; Weightlessness; Microscopy; Euglena gracilis; Flagellum; Gravitaxis; Weightlessness; cAMP; μ g; Euglenophyta; Plant physiology; Algae; Taxis; Gravity
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1016/j.jplph.2009.07.009

The unicellular freshwater flagellate
Euglena gracilis shows negative gravitactic behavior. Previous experiments have revealed that the orientation is most likely an active physiological process in which the beating pattern of the flagellum is controlled by gravity and mediated by a change in the calcium concentration inside the cell. In a signal transduction chain, the calcium signal activates a calmodulin, which in turn raises the concentration of cAMP. This alters the beating pattern of the flagellum; reorientation is therefore not a passive process driven by buoyancy. In a recent parabolic flight experiment (ESA 45th parabolic flight campaign), we observed the beating of the flagellum with a high-resolution light microscope. Transition from hyper
g to μ
g as well as from μ
g to hyper
g caused a change of the beating pattern of the flagellum, which confirmed the physiological nature of the process. In μ
g cells stopped moving the flagellum or tried to reorient, while in hyper
g, the cells realigned consecutively. The reaction times for the flagellar responses in previous experiments are confirmed.