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Gravitation and light dependent swimming behaviour in
Ophryoglena flava. A direction dependent photokinesis?
Jan Bechert, Richard Bräucker
DLR School Lab Köln-Porz
Ciliates show a distinct coupling between membrane potential and
ciliary movement. Hence, it is possible to determine the state of
excitation of the cell by analyzing the swimming behaviour.
Ophryoglena flava, a holotrich sarcophagous ciliate, shows an active
reaction to the gravity vector, compensating about 55% of the cell’s
sedimentation rate.
A kinesis is commonly defined as a change in locomotion velocity
dependent on the value of the stimulus and not on stimulus direction.
Gravikinesis, as exception, depends as well on the value as on the
direction of acceleration. This has been demonstrated by means of
centrifugal experiments and in parabolic flights.
Besides from graviresponse, Ophryoglena flava also shows a reaction
to unidirectional light, which may be caused by the organelle of
Lieberkühn. We present new data of wavelength and light direction
dependent photoreactions in Ophryoglena. The data imply that
photoreaction in this species is composed of photoorientation and a
light direction dependent kinesis.
jan.bechert@dlr.de
richard.braeucker@dlr.de
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