| Project/Area Number |
11837010
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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 Institution | Osaka University |
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Principal Investigator |
KIKOCHI Macoto Graduate School of Science, Osaka University Professor, サイバーメディアセンター, 教授 (50195210)
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| Co-Investigator(Kenkyū-buntansha) |
CHAWANYA Tsuyoshi Graduate School of Science, Osaka University Lecturer, 大学院・理学研究科, 講師 (80294148)
TOKITA Kei Graduate School of Science, Osaka University Research Associate, サイバーメディアセンター, 助教授 (00263195)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥4,100,000 (Direct Cost: ¥4,100,000)
Fiscal Year 2000: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1999: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Keywords | ecosystem / protein / evolution / dynamical system / extinction / diversity / folding / レプリケーター方程式 / 計算機シミュレーション / フォールディング / 生体系 |
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| Research Abstract |
1. Extinction and Speciation Dynamics of Large-scale Ecosystem
Introducing the effect of extinction into the so-called replicator equations, we constructed a general model where the diversity of species is a dynamical variable. The system shows very different behavior from the original equation and leads to mass extinction when the system initially has high diversity. We further introduced the effects of invasion and mutation into the system and obtained the following conclusions : (1) interspecies interactions become more symbiotic under the pressure of natural selection ; (2) a complex ecosystem can emerge when temporally neutral mutants are introduced ; (3) such ecosystem possesses strong resistance to invasion ; (4) a typical process of fixation of mutants is realized through the rapid growth of a group of symbiotic mutants with higher fitness than majority species ; (5) a hierarchical taxonomic structure (like family-genus-species) emerges ; and (6) the relative abundance of specie
… More
s exhibits a typical pattern widely observed in nature.
2. Dynamical Structure of Large-scale Ecosystem
We investigated the dynamical structure related to spontaneous interchange of major species and found that this structure is relevant to several other systems. We proposed a new mechanism for maintaining diversity in systems dominated by competing interactions.
3. Role of Non-native Interaction in the Evolution of Protein
β-lactoglobulin is known to exhibit an anomalous folding process in which an accumulation of non-native α-helices is observed in the folding intermediate while the native state is β-sheet dominated. Our principal question here is why the non-native intermediate state has not been eliminated in the course of the Darwinian evolution. Based on lattice model simulations, we found that the free-energy landscape bears a highly "non-funnel" nature and the intermediate state is "on-pathway". The result indicate that the folding intermediate have some active role in the folding process, and has thus been conserved through the evolution. Less
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