Euglena gracilis photoreception interpreted by microspectroscopy

For over 100 years, Euglena gracilis has represented a major subject for photobiological studies. This unicellular flagellate is well suited for such investigations because of its special complement of organelles that may be considered an ancient, yet complete "visual" system. The actual photoreceptive roles of the cytoplasmic eyespot and the photoreceptor (old terminology: paraflagellar swelling) of E. gracilis are still under debate, because of the different experimental evidence produced by the different research groups still working on this organism. This paper presents the analysis of the spectroscopical measurements performed by our group, which forms the basis of a possible model for Euglena photoresponses