| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2015: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2014: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2013: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
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| Outline of Final Research Achievements |
Unlike bacteria such as Escherichia coli, freshwater cyanobacteria are known to contain multiple chromosomal copies per cell, at all stages of their cell cycle. Our studies have revealed that DNA replication of multi-copy chromosome is not tightly coupled to cell division in the cyanobacterium Synechococcus elongatus PCC 7942 (hereafter S. 7942). Here, we report the growth phase-dependent regulation of chromosomal copy number: it was significantly higher during the lag phase than during the following phases. To address the factors involved in the copy number regulation, we analysed the transcriptome and metabolome at each growth phase. The results of these analyses suggest that the phosphate-starvation response occurred at the late-linear phase. Correspondingly, the phosphate ion was almost lost in the late-linear phase culture. Phosphate is a primary substrate for DNA synthesis, thus we concluded that the chromosome copy number depends on the phosphate amount in the culture.
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