| Project/Area Number |
14598005
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
ポストゲノムのナノサイエンス
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| Research Institution | College of Nagoya Bunri University |
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Principal Investigator |
YOSHIKAWA Yuko Nagoya Bunri College, Department of Food and Nutrition, Professor, 食物栄養学科, 教授 (80291871)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2004: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2003: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2002: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | fluorescence microscopy / single-molecule observation / long duplex DNA / higher order structure / double-strand break / reconstituted chromatin / ascorbic acid / daunomycin / 折り畳み構造 / 抗酸化作用 / DNA損傷 / 単分子観察 / アスコルビン酸 / 原子間力顕微鏡 / 高次構造 / 自己組織化ナノ構造 / パーリング構造 / DNAの折りたたみ構造 / 蛍光顕微鏡観察 / リポソーム |
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| Research Abstract |
Recently, the methods of single-molecule observation have been utilized to study molecular mechanisms of biological reactions in vitro. With fluorescence microscopy, I have made direct observations of single giant DNA molecules in solution and have found that giant DNA molecules change their conformation depending on environmental conditions.
The main results in the present study are summarized as follows.
(1) I studied the effect of daunomycin, a cancer chemotherapeutic agent, on a model cellular system in which folded compact DNA was encapsulated inside a cell-sized phospholipid liposome. Following the exposure to daunomycin, the compact DNA inside a liposome was gradually elongated and then cut into a pair of fragments. It has become clear that daunomycin can penetrate the bilayer lipid membrane and has the potential effect to loosen the packing of DNA together with the activity to cut the double stranded DNA. Our results imply that cell-sized liposomes are useful as a simple model of living cells.
(2) I examined the effect of ascorbic acid on the higher order structure of DNA through single molecular observation with fluorescence microscopy, and found that ascorbic acid generates a pearling structure in giant DNA molecules, where elongated and compact parts coexist along a molecular chain. The results of observations with atomic force microscopy indicate that the compact parts assume a loosely packed conformation. It has been reported that human circulating immune cells, such as neutrophils, monocytes and lymphocytes, accumulate ascorbic acid in millimolar concentrations. Therefore, it is expected that the ascorbic acid concentration that induces the large conformational change on DNA may be of physiological significance.
(3) I investigated the effect of ascorbic acid on preventing DNA double-strand breaks in reconstituted chromatin in relation to the highly compacted polynucleosomal structure.
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