PHOTOPOLARIZATION OF THE FUCUS SP ZYGOTE BY BLUE-LIGHT INVOLVES A PLASMA-MEMBRANE REDOX CHAIN

Zygotes of fucoid algae are photopoiarized by unidirectional blue ligh t (BL). Polar axes are formed, fixed, and expressed by germination of a rhizoid. Hexacyanoferrate(III) ions (HCF) specifically inhibit trans duction of the BL signal. HCF reduction by Fucus sp. zygotes occurs on the outer surface of the plasma membrane at higher rates in BL than i n dark. These observations suggest that BL signal transduction involve s a redox chain in the plasma membrane. Low doses of HCF (<50 pmol cel l(-1)) inhibit photopolarization but not germination, hence uncoupling both processes. Exposure during the photosensitive period to higher d oses of HCF together with BL significantly inhibits germination. Furth er results suggest that BL transduction is dependent on photosynthetic products that could also interact with redox processes.