大岩 和弘

Active matter consists of self-propelled elements exhibits fascinating collective motions ranging from biological to artificial systems. Among wide varieties of active matter systems, reconstituted bio-filaments moving on molecular motor turf interacting purely by physical interactions provides the fundamental test ground for understanding biological motility. However, until now, multi-filament collisions,depletion agents or binding molecules has been required for the emergence of ordered patterns in motility assay. Thus, whether simple physical interactions during collisions such as steric effect without depletion nor binding agents are sufficient or not for producing ordered patterns in motility assays remains still elusive. In this article, we constructed a motility assay purely consists of kinesin motor and microtubule in which the frequency of binary collision can be controlled without using depletion nor binding agents. By controlling strength of steric interaction and density of microtubules, we found different states; disordered state, long-range orientationally ordered state, liquid-gas-like phase separated state, and transitions between them. We found that a balance between cross over and aligning events in collisions controls transition from disorder to global ordered state, while excessively strong steric effect leads to the phase separated clusters. Furthermore, macroscopic chiral symmetry breaking observed as a global rotation of nematic order observed in this experiment could be attributed to the chirality at molecular level. Numerical simulations in which we change strength of volume exclusion reproduce these experimental results. Moreover, it reveals the transition from long-range alignment to nematic bands then to aggregations. This study may provide new insights into dynamic ordering by self-propelled elements through a purely physical interaction.

An simulation analysis on the control of bionanonetworks of DNA nanomachines using solitons induced by the terahertz radiation is presented. It is expected that the soliton breather wave in DNA can promote the branch migration to lead the effective change of the network formation toward the successful missions. Our results show new possibilities of terahertz communication through the regulation of bio-nanonetworks that consist of artificial molecular machines.

モレウェア・コミュニケーションのための数学モデルを提案するし、計算機科学の方法によってキナーゼ・シグナリング・パスウェイと分子モーターにおける情報処理メカニズムを定式化される。A mathematical model for moleware communications is proposed in terms of theories of computer science to formulate the information processing mechanism of signaling pathways related to kinases and molecular motors.

生体内に存在するタンパク質分子は,熱揺動と同程度の小さな入力エネルギーを有効に利用して,相互作用しながら高度な機能を発現するナノマシンである.本研究では,この機能発現の原理を探るため,タンパク質分子間あるいは分子内に働く極微弱な力学的相互作用を,探針を用いて計測するシステムを構築した.このシステムでは,従来の微小力測定法では避けることのできない熱揺らぎや力発生に伴う探針の位置の不確定性を排除した.すなわち,光が物体に及ぼす力を利用したフィードバック制御技術の開発により,探針の位置をナノメートルの精度で制御しながらピコニュートンレベルの力を測定することができるようにした.更に,モータタンパク質分子が発生する力を実際に測定し,生体分子が機能を発現するために必須の条件である溶液中において,この測定システムが有効に機能することを示した.