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Is the adhesive material secreted by sea urchin tube feet species-specific?

Authors

  • Romana Santos,

    Corresponding author
    1. Université de Mons—UMONS, Académie Universitaire Wallonie Bruxelles, Laboratoire de Biologie Marine, Mons 7000, Belgium
    2. Unidade de Investigação em Ciências Orais e Biomédicas, Faculdade de Medicina Dentária, Universidade de Lisboa, Cidade Universitária, Lisboa 1649-003, Portugal
    • Unidade de Investigação em Ciências Orais e Biomédicas, Faculdade de Medicina Dentária, Universidade de Lisboa, Cidade Universitária, Lisboa 1649-003, Portugal
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  • Patrick Flammang

    Corresponding author
    1. Université de Mons—UMONS, Académie Universitaire Wallonie Bruxelles, Laboratoire de Biologie Marine, Mons 7000, Belgium
    • Université de Mons—UMONS, Académie Universitaire Wallonie Bruxelles, Laboratoire de Biologie Marine, 20 Place du Parc, Mons 7000, Belgium
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Abstract

Sea urchin adoral tube feet are highly specialized organs that have evolved to provide efficient attachment to the substratum. They consist of a disk and a stem that together form a functional unit. Tube foot disk tenacity (adhesive force per unit area) and stem mechanical properties (e.g., stiffness) vary between species but are apparently not correlated with sea urchin taxa or habitats. Moreover, ultrastructural studies of sea urchin disk epidermis pointed out differences in the internal organization of the adhesive secretory granules among species. This prompted us to look for interspecific variability in the composition of echinoid adhesive secretions, which could explain the observed variability in adhesive granule ultrastructure and disk tenacity. Antisera raised against the footprint material of Sphaerechinus granularis (S. granularis) were first used to locate the origin of adhesive footprint constituents in tube feet by taking advantage of the polyclonal character of the generated antibodies. Immunohistochemical assays showed that the antibodies specifically labeled the adhesive secretory cells of the disk epidermis in the tube feet of S. granularis. The antibodies were then used on tube foot histological sections from seven other sea urchin species to shed some light on the variability of their adhesive substances by looking for antibody cross-reactivity. Surprisingly, no labeling was observed in any of the species tested. These results indicate that unlike the adhesive secretions of asteroids, those of echinoids do not share common epitopes on their constituents and thus would be “species-specific.” In sea urchins, variations in the composition of adhesive secretions could therefore explain interspecific differences in disk tenacity and in adhesive granule ultrastructure. J. Morphol., 2011. © 2011 Wiley Periodicals, Inc.

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