| Autor: |
Wolfgang Lueken, Thomas Krüppel, Nicola Ricci |
| Rok vydání: |
1996 |
| Předmět: |
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| Zdroj: |
European Journal of Protistology. 32:47-54 |
| ISSN: |
0932-4739 |
| DOI: |
10.1016/s0932-4739(96)80038-1 |
| Popis: |
Summary In the marine hypotrich Euplotes vannus, the coupling of behavioural elements to shifts in the freely fluctuating membrane potential was investigated by use of a computerized locomotion track evaluation system. Potential shifts were attributed to beating of cirri by single-image analysis of simultaneous video-tape-recordings. Walking speed rhythmically decreases for 150–200 ms, and increases for 550–670 ms with a frequency of ~ 1.3/s. This pattern is caused by repetitive, spontaneous depolarizations of ~ 200 ms duration from about − 25 mV to about − 15 mV with a similar frequency. The speed is decreased by the combined reduction of the stroke amplitude of the fronto-ventral cirri and anteriad bending of the transverse cirri. Both the depolarizations and the walking pattern persist in a solution with a reduced Ca2+ activity of 50 μmol/l. Arhythmic spontaneous long depolarizations of 600–1200 ms duration induce a deceleration until movements stop and a fast backward jerking upon reversal of the beat direction of all cirri. This “side-stepping” (“avoiding”) reaction requires a high extracellular calcium concentration. Presumably, the depolarization rhythm is based on a pacemaking sequence of conductance changes of potassium. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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