Abstract
Coenocytic alga, Vaucheria (Stramenopile) exhibits phototropism to blue-light (BL). The alga also shows a photocytomorphogenetic response: a growth point is induced at the center of BL-irradiated region of the cell. For this response not only chloroplast- and nuclear accumulation, but also gene expression by the irradiated nuclei is indispensable. We have isolated cDNAs encoding two novel LOV-proteins from V. frigida by means of RT-PCR and 3'- and 5' RACE. To date it is still obscure whether Vauchria lacks phototropin. The two LOV-proteins, made of ca. 350 aa., resemble each other. At least one of them may serve as a BL-receptor, because its LOV domain, heterologously expressed in E. coli, bound with FMN. The both fusion proteins with GFP expressed in onion epidermis were located in nuclei. RNAi is used to elucidate what BL response is mediated by these photoreceptors.
