title: Interfibrillar stiffening of echinoderm mutable collagenous tissue demonstrated at the nanoscale.
abstract: The mutable collagenous tissue (MCT) of echinoderms (e.g., sea cucumbers and starfish) is a remarkable example of a biological material that has the unique attribute, among collagenous tissues, of being able to rapidly change its stiffness and extensibility under neural control. However, the mechanisms of MCT have not been characterized at the nanoscale. Using synchrotron small-angle X-ray diffraction to probe time-dependent changes in fibrillar structure during in situ tensile testing of sea cucumber dermis, we investigate the ultrastructural mechanics of MCT by measuring fibril strain at different chemically induced mechanical states. By measuring a variable interfibrillar stiffness (EIF), the mechanism of mutability at the nanoscale can be demonstrated directly. A model of stiffness modulation via enhanced fibrillar recruitment is developed to explain the biophysical mechanisms of MCT. Understanding the mechanisms of MCT quantitatively may have applications in development of new types of mechanically tunable biomaterials.
authors.affiliation: School of Engineering and Material Science, Queen Mary University of London, London, E1 4NS, United Kingdom.
authors.forename: Jingyi
authors.initials: J
authors.lastname: Mo
authors.affiliation: Beamline ID02, European Synchrotron Radiation Facility, Grenoble 38000, France.
authors.forename: Sylvain F
authors.identifier: 0000-0002-6008-1987
authors.initials: SF
authors.lastname: Prévost
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, United Kingdom.
authors.forename: Liisa M
authors.initials: LM
authors.lastname: Blowes
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, United Kingdom.
authors.forename: Michaela
authors.initials: M
authors.lastname: Egertová
authors.affiliation: Beamline I22, Diamond Light Source, Harwell Science and Innovation Campus, Harwell, OX11 0DE, United Kingdom.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Terrill
authors.affiliation: School of Engineering and Material Science, Queen Mary University of London, London, E1 4NS, United Kingdom; Institute of Bioengineering, Queen Mary University of London, London, E1 4NS, United Kingdom.
authors.forename: Wen
authors.initials: W
authors.lastname: Wang
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, United Kingdom; h.gupta@qmul.ac.uk M.R.Elphick@qmul.ac.uk.
authors.forename: Maurice R
authors.initials: MR
authors.lastname: Elphick
authors.affiliation: School of Engineering and Material Science, Queen Mary University of London, London, E1 4NS, United Kingdom; Institute of Bioengineering, Queen Mary University of London, London, E1 4NS, United Kingdom h.gupta@qmul.ac.uk M.R.Elphick@qmul.ac.uk.
authors.forename: Himadri S
authors.initials: HS
authors.lastname: Gupta
mesh_terms: D000465:Algorithms; D000818:Animals; D001696:Biomechanical Phenomena; D003094:Collagen / Q000737:chemistry; D004447:Echinodermata; D005109:Extracellular Matrix / Q000737:chemistry*; D008962:Models, Theoretical; D012616:Sea Cucumbers; D013215:Starfish; D014961:X-Ray Diffraction
chemical_list: D003094:Collagen
keywords: fibrillar deformation; mutable collagenous tissue; nanoscale mechanics; sea cucumbers; synchrotron small-angle X-ray diffraction