| Budget Amount *help |
¥12,800,000 (Direct Cost: ¥12,800,000)
Fiscal Year 2002: ¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 2001: ¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 2000: ¥6,400,000 (Direct Cost: ¥6,400,000)
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| Research Abstract |
Euglena gracilis, a unicellular flagellate, shows abrupt changes in its swimming direction in response to a sudden increase or decrease in incident light intensity (i.e.step-up or step-down photophobic responses), rsulting in photoavoidance or photoaccumlation, respectively.In addition, it shows positive and negative phototaxis (movement toward or away from the light source, respectively).In 2002, Iseki et al (Nature 415, 1047-1051) identified a flavoprotein in the photosensory organelle of Euglena as a photoreceptor for the step-up photophobic response.The flavoprotein, named photoactivated adenylyl cyclase (PAC), shows an apparent molecular mass of 400 kDa and seems to be a heterotetramer of α-and β-subunits.The subunits are similar to each other and contain two FAD-binding domains (BLUF domain) each followed by an adenylyl cyclase catalytic domain.PAC exhibits adenylyl cyclase activity, which is drastically elevated by blue-light irradiation. Recently, we found that suppression of gene expression of PAC by RNAi impaired not only the step-up photophobic response but also positive and negative phototaxis, which implies that PAC or its similar molecules are involved in phototactic orientation of Euglena (Ntefidou, et al. Plant Physiol. 133, 1517-21).
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