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| 2. |
- Ekelund, Nils, 1956-
(författare)
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Effects of calcium channel blockers and DCMU on motility and the photophobic response of Gyrodinium dorsum
- 1989
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Ingår i: Archives of Microbiology. - 0302-8933 .- 1432-072X. ; 151, s. 187-190
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Tidskriftsartikel (refereegranskat)abstract
- The effects of the calcium channel blockers, verapamil, diltiazem and lanthanum ions and the Ca2+ dependency on motility as well as the photophobic response (stop-response) of Gyrodinium dorsum were studied. At Ca2+ concentrations below 10-3 M, motility was inhibited. La3+ inhibits the stop-response, in contrast to verapamil and diltiazem. The only calcium channel blocker that increased the amount of non-motile cells was verapamil. The results indicate that motility are Ca2+ dependent and that the stop-responses of G. dorsum could be affected by extracellular Ca2+. Effects of the photosythesis inhibitor (DCMU) on the stop-response was also determined. With background light of different wavelength (614, 658 and 686 nm) the stop-response increased. DCMU inhibited this effect of background light. Negative results with the monoclonal antibody Pea-25 directed to phytochrome and the results with DCMU, indicate that the stop-response of G. dorsum is coupled to photosynthesis rather than to a phytochrome-like pigment. Oxygen evolution, but not cell movement, was completely inhibited by 10-6 M DCMU.
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| 3. |
- Ekelund, Nils, 1956-
(författare)
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Ljusrörelser hos mikroorganismer
- 1988
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Ingår i: Svensk Botanisk Tidskrift. - 0039-646X. ; 82, s. 333-336
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 4. |
- Ekelund, Nils, 1956-, et al.
(författare)
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Photomovement and photobleaching in two Gyrodinium species
- 1988
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Ingår i: Plant and Cell Physiology. - : Oxford University Press (OUP). - 0032-0781 .- 1471-9053. ; 29, s. 1109-1114
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Tidskriftsartikel (refereegranskat)abstract
- The phototactic orientation in Gyrodinium dorsum and G. aureolum has been analyzed. Both species show only positive phototaxis with an optimum at about 300 W-m–2. The mechanism of photoorientation does not seem to be based on a dichroic orientation of the photoreceptor pigments as in the flagellate Euglena gracilis. Photobleaching experiments have shown a far higher resistance toward continuous irradiation at even high fluence rates than in other flagellates which is in good agreement with the exclusive behavior of positive phototaxis.
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| 5. |
- Ekelund, Nils, 1956-, et al.
(författare)
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Phototactic responses of Chlamydomonas reinhardtii in electric fields
- 1988
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 73, s. 265-270
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Tidskriftsartikel (refereegranskat)abstract
- Chlamydomonas reinhardtii Dangeard strain Göttingen 11 – 32(+) responds both phototactically and galvanotactically. If electric fields and a light stimulus of 496 nm were applied simultaneously, phototaxis persisted but the response was modified. Field lines perpendicular to the phototactic direction of movement inhibited phototaxis. If the field lines were parallel to the light direction, the effect depended on the position of the poles. When the cathode faced the light, an increase of the phototactic reaction values was observed. In this case electric fields enhanced positive phototaxis with increasing voltages from 3 V up to 12 V. If the cathode was on the opposite side, positive phototactic movement was inhibited. The maximum inhibition was found at 12 V. At this voltage positive phototaxis was measured neither at low nor at high fluence rates, and positive phototaxis was shown only between 0.1 and 1.5 W m−1.
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| 6. |
- Ekelund, Nils, 1956-
(författare)
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Öresund
- 1989
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Rapport (populärvet., debatt m.m.)
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