| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2005: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2004: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Research Abstract |
1.Through disrupting the sqdB gene for synthesis of an acidic lipid sulfoquinovosyl diacylglycerol (SQDG), a mutant deficient in SQDG was produced from a cyanobacterium Synechococcus sp.PCC7002 for its physiological characterization. The mutant showed normal photosynthetic ability and growth, indicating that SQDG is dispensable for this species, as is similar to Synechococcus sp.PCC7942, but is distinct from Synechocystis sp.PCC6803 that requires SQDG for photosynthesis and growth. Molecular phylogenic tree of the primary structure of SqdB indicated that the type of PCC7002 belongs to that of PCC7942, but not of PCC6803. These results were consistent with our notion that SqdB evolved in harmony with acquisition of SQDG-requirement for photosynthesis during evolution of cyanobacteria.
2.A green alga Chlamydomonas reinhardtii, when exposed to deprivation of external sulfate, showed mobilization of sulfur of SQDG to other compounds, concomitantly with maintenance of capacity to synthesize SQDG probably through enhancement of mRNA level of SQD1 gene for UDP-sulfoquinovose synthase. The results implied that, under the sulfur-stress condition, SQDG not only is utilized as the internal sulfur-source, but also is crucial for regulation of some cellular function.
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