title: Instantaneous adhesion of Cuvierian tubules in the sea cucumber Holothuria forskali.
abstract: The peculiar Cuvierian tubules of sea cucumbers function as a defense mechanism. They thwart attacks by creating a sticky network composed of elongated tubules within which the potential predator is entangled in a matter of seconds and thus immobilized. Cuvierian tubules are typical instantaneous adhesive organs in which tissue integrity is destroyed during the release of the adhesive secretion. However, very little information is available about this adhesion process. The adhesive epithelium-the mesothelium-and the sticky material it produces were studied in the species Holothuria forskali using different microscopy techniques (light microscopy, transmission electron microscopy, scanning electron microscopy, and atomic force microscopy). The mesothelium consists of two cell types-peritoneocytes and granular cells-organized in superimposed layers. In tubules before expulsion, peritoneocytes form an outer protective cell layer preventing adhesion when not needed. After expulsion, the elongation process removes this protective layer and allows granular cells to unfold and to become exposed at the tubule surface. At this stage, Cuvierian tubules are still not sticky. Upon contact with a surface, however, granular cells release their granule contents. Once released, this material changes in aspect, swells, and spreads readily on any type of substrate where it forms a thin homogeneous layer. After tubule peeling, this layer remains on the surface but is often contaminated with collagen fibers. Atomic force microscopy demonstrated the adhesive layer to be made up of globular nanostructures measuring about 70 nm in diameter and to be more adhesive than the collagen fibers left on it. The morphological organization of Cuvierian tubules therefore allows contact-dependent deposition of an adhesive material presenting a high affinity for various surfaces. It is certainly an adaptive advantage for a defense organ to be able to entangle different types of predators.
authors.affiliation: Research Institute for Biosciences, Biology of Marine Organisms and Biomimetics, University of Mons-UMONS, Mons 7000, Belgium.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Demeuldre
authors.affiliation: Laboratory for Chemistry of Novel Materials, Research Institute for Materials Science and Engineering, Center of Innovation and Research in Materials and Polymers (CIRMAP), University of Mons-UMONS, Mons 7000, Belgium.
authors.forename: Thi
authors.initials: T
authors.lastname: Chinh Ngo
authors.affiliation: Research Institute for Biosciences, Biology of Marine Organisms and Biomimetics, University of Mons-UMONS, Mons 7000, Belgium.
authors.forename: Elise
authors.initials: E
authors.lastname: Hennebert
authors.affiliation: Laboratory of Proteomics and Microbiology, Research Institute for Biosciences, University of Mons-UMONS, Mons 7000, Belgium.
authors.forename: Ruddy
authors.initials: R
authors.lastname: Wattiez
authors.affiliation: Laboratory for Chemistry of Novel Materials, Research Institute for Materials Science and Engineering, Center of Innovation and Research in Materials and Polymers (CIRMAP), University of Mons-UMONS, Mons 7000, Belgium.
authors.forename: Philippe
authors.initials: P
authors.lastname: Leclère
authors.affiliation: Research Institute for Biosciences, Biology of Marine Organisms and Biomimetics, University of Mons-UMONS, Mons 7000, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Flammang
mesh_terms: D000268:Adhesiveness; D000269:Adhesives / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D012634:Bodily Secretions; D004848:Epithelium / Q000378:metabolism / Q000648:ultrastructure; D047332:Holothuria / Q000378:metabolism*; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures / Q000737:chemistry; D010316:Particle Size; D012137:Respiratory System / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D000269:Adhesives