title: Liquid Crystalline Granules Align in a Hierarchical Structure To Produce Spider Dragline Microfibrils.
abstract: The spider silk spinning process converts spidroins from an aqueous form to a tough fiber. This spinning process has been investigated by numerous researchers, and micelles or liquid crystals of spidroins have been reported to form silk fibers, which are bundles of silk microfibrils. However, the formation process of silk microfibrils has not been clarified previously. Here, we report that silk microfibrils are generated through the formation, homogenization, and linkage of liquid crystalline granules without micelle-like structures. Heterogeneous granules on the submicron to micron scale were observed in the storage sac, whereas homogeneous granules with diameters of approximately 100 nm were aligned along the tapering duct. In the spun fibers, the homogeneous granules were connected along the fiber axis. This is the first clear description of the formation of granule-based microfibrils in the spinning process, which is the key conversion process leading to the unique hierarchical structure of spider dragline.
authors.affiliation: Enzyme Research Team, RIKEN Center for Sustainable Resource Science , 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Ting-Yu
authors.initials: TY
authors.lastname: Lin
authors.affiliation: Japan Synchrotron Radiation Research Institute , 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Masunaga
authors.affiliation: Enzyme Research Team, RIKEN Center for Sustainable Resource Science , 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Sato
authors.affiliation: Enzyme Research Team, RIKEN Center for Sustainable Resource Science , 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Ali D
authors.initials: AD
authors.lastname: Malay
authors.affiliation: Mass Spectrometry and Microscopy Unit, Technology Platform Division, RIKEN Center for Sustainable Resource Science , 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045 Japan.
authors.forename: Kiminori
authors.initials: K
authors.lastname: Toyooka
authors.affiliation: RIKEN SPring-8 Center , 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Hikima
authors.affiliation: Enzyme Research Team, RIKEN Center for Sustainable Resource Science , 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Keiji
authors.identifier: 0000-0003-2199-7420
authors.initials: K
authors.lastname: Numata
mesh_terms: D000818:Animals; D005260:Female; D005349:Fibroins / Q000737:chemistry* / Q000648:ultrastructure; D050866:Liquid Crystals / Q000737:chemistry* / Q000648:ultrastructure; D020894:Microfibrils / Q000737:chemistry* / Q000648:ultrastructure; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D013112:Spiders / Q000033:anatomy & histology
chemical_list: D005349:Fibroins