PHOTOBEHAVIOR OF EUGLENA GRACILIS: ACTION SPECTRUM FOR THE STEP-DOWN PHOTOPHOBIC RESPONSE OF INDIVIDUAL CELLS |
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| Authors: | Corrado Barghigiani Giuliano Colombetti Barbara Franchini Francesco Lenci |
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| Institution: | C.N.R., Laboratorio Studio ProprietáFisiche Biomolecole e Cellule, Via F. Buonarroti, 9, 56100 Pisa. Italy |
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| Abstract: | Abstract—Light-induced behavioral responses of Euglena gracilis have been investigated in single cells by means of a video system coupled to an optical microscope. Light intensity-effect curves at different wavelengths in the near UV and visible range have been determined. From these curves the action spectrum for the step-down photophobic response of Euglena has been calculated. From a comparison with the results obtained using a population method by means of a phototaxigraph, it is concluded that a single photomotile reaction is responsible for cell accumulation, brought about by trapping in the light spot and possibly by phototaxis towards scattered light from organisms already in the light field. |
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