| Budget Amount *help |
¥3,560,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2011: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2010: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
gamma-Hexachlorocyclohexane (gamma-HCH)is a completely man-made chlorinated pesticide that has caused serious environmental problems due to its toxicity and long persistence in upland soils. In our previous study, the complete genome sequence of an archetypal gamma-HCH-degrading strain, Sphingobium japonicum UT26, was determined. The ‘specific' lin genes (linA to linE)for the conversion of gamma-HCH to maleylacetate are dispersed on chromosome 1 (linA, linB, and linC)and a plasmid pCHQ1 (linD and linE)in the UT26 genome. IS6100 is often found in close proximity to the ‘specific' lin genes not only in UT26 but also in other gamma-HCH-degrading strains. To get more insights into the appearance and evolution of gamma-HCH-degrading bacteria, the draft genome sequences of three other such strains, Sphingomonas sp. MM-1, Sphingobium sp. TKS, and Sphingobium sp. MI1205 (5), which were isolated at geographically different area with one another, were determined and compared with the complete ge
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nome sequences of UT26 and other closely related but non-gamma-HCH-degrading sphingomonad strains. All the former three gamma-HCH-degrading strains also have the ‘specific' lin genes, but the location of such genes on their genomes are different from that on UT26, and for example, MM-1 carries such genes on three plasmids. Furthermore, genome contents and organizations of the four gamma-HCH-degraders are different with one another. These results suggested that these degraders had been created independently by lateral gene transfer of the ‘specific' lin genes. Analysis of flanking regions of 13 copies of IS6100 in UT26 suggested the DNA exchanges between chromosome and plasmids via the IS6100 transposition. Our use of sacB-based IS entrapment technique indeed revealed the transposability of endogenous IS6100 in UT26. These results strongly suggested that IS6100 plays important roles in the dissemination of the ‘specific' lin genes among gamma-HCH-degrading bacteria as well as in their genome rearrangements Less
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