title: Isomorphic coalescence of aster cores formed in vitro from microtubules and kinesin motors.
abstract: We report fluorescence microscopy studies of the formation of aster-like structures emerging from a cellular element-based active system and a novel analysis of the aster condensation. The system consists of rhodamine labeled microtubules which are dynamically coupled by functionalized kinesin motor proteins cross-linked via streptavidin-coated quantum dots (QDs). The aster-shaped objects contain core structures. The cores are aggregates of the QD-motor protein complexes, and result from the dynamic condensation of sub-clusters that are connected to each other randomly. The structural specificity of the aster core reflects a configuration of the initial connectivity between sub-clusters. Detailed image analysis allows us to extract a novel correlation between the condensation speed and the sub-cluster separation. The size of the core is scaled down during the condensation process, following a power law dependence on the distance between sub-clusters. The exponent of the power law is close to two, as expected from a geometric model. This single exponent common to all the contractile lines implies that there exists a time regime during which an isomorphic contraction of the aster core continues during the condensation process. We analyze the observed contraction by using a model system with potential applicability in a wide range of emergent phenomena in randomly coupled active networks, which are prevalent in the cellular environment.
authors.affiliation: WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kim
authors.forename: A
authors.initials: A
authors.lastname: Sikora
authors.forename: H
authors.initials: H
authors.lastname: Nakazawa
authors.forename: M
authors.initials: M
authors.lastname: Umetsu
authors.forename: W
authors.initials: W
authors.lastname: Hwang
authors.forename: W
authors.initials: W
authors.lastname: Teizer
mesh_terms: D000818:Animals; D004331:Drosophila melanogaster / Q000166:cytology*; D004926:Escherichia coli / Q000235:genetics; D005656:Fungal Proteins / Q000378:metabolism*; D019476:Insect Proteins / Q000378:metabolism*; D016547:Kinesins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism*; D009492:Neurospora crassa / Q000166:cytology*; D030781:Organisms, Genetically Modified
chemical_list: D005656:Fungal Proteins; D019476:Insect Proteins; D016547:Kinesins