Circadian rhythm of gravitaxis in Euglena gracilis.

Lebert M, Porst M, Häder DP (1999)

Publication Type: Journal article

Publication year: 1999


Publisher: Elsevier

Book Volume: 155

Pages Range: 344 - 349

DOI: 10.1016/S0176-1617(99)80115-1


Euglena gracilis, a unicellular, photosynthetic flagellate is a model system for environmentally controlled behavioral reactions. One pronounced reaction is the orientation with respect to gravity. In synchronized cultures with no cell growth a distinct circadian rhythm of negative gravitactic orientation could be observed. The main maximum of sensitivity was detected 5 h after the beginning of the subjective day, the main minimum 5 h before the beginning of the subjective day. Transferring synchronized cultures to continuous light resulted in an almost instantaneous loss of rhythmicity. In contrast, after transfer to permanent darkness cells exhibited a circadian rhythm with a progressive shortening of the period for more than 5 days. These findings are in contrast to the circadian rhythm of phototaxis in Euglena, where a free-running period of 24 h was observed. Parallel measurements of negative gravitactic orientation, velocity, cell shape as well as cAMP concentration in synchronized cultures revealed a circadian rhythm of all reactions. The results are discussed with regard to the possible role of cell shape and cAMP in gravitactic orientation.

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Lebert, M., Porst, M., & Häder, D.-P. (1999). Circadian rhythm of gravitaxis in Euglena gracilis. Journal of Plant Physiology, 155, 344 - 349.


Lebert, Michael, Markus Porst, and Donat-Peter Häder. "Circadian rhythm of gravitaxis in Euglena gracilis." Journal of Plant Physiology 155 (1999): 344 - 349.

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