FLAGELLUM AUTOFLUORESCENCE and PHOTOACCUMULATION IN HETEROKONT ALGAE

Zoids of various brown algae capable of positive or negative phototaxis show strong autofluorescence of their posterior fiagellum and flagellar swelling when excited with blue light of 450 nm. This effect is lacking in zoids without stigma and phototactic capability. Fluorescence studies on living cells point to a flavin as photoreceptor pigment. The spectral sensitivity curve of photoaccumul-ation suggests a carotenoid pigment (maximum 430–450 nm) being involved, with no effect below 380 nm and above 540 nm. The results obtained in this study indicate a flavin as photoreceptor pigment, which is periodically shaded by a carotenoid stigma.