Mineralization of the metre-long biosilica structures of glass sponges is templated on hydroxylated collagen

Journal name:
Nature Chemistry
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The minerals involved in the formation of metazoan skeletons principally comprise glassy silica, calcium phosphate or carbonate. Because of their ancient heritage, glass sponges (Hexactinellida) may shed light on fundamental questions such as molecular evolution, the unique chemistry and formation of the first skeletal silica-based structures, and the origin of multicellular animals. We have studied anchoring spicules from the metre-long stalk of the glass rope sponge (Hyalonema sieboldi; Porifera, Class Hexactinellida), which are remarkable for their size, durability, flexibility and optical properties. Using slow-alkali etching of biosilica, we isolated the organic fraction, which was revealed to be dominated by a hydroxylated fibrillar collagen that contains an unusual [Gly3Hyp4Hyp] motif. We speculate that this motif is predisposed for silica precipitation, and provides a novel template for biosilicification in nature.

At a glance


  1. Marine glass sponge Hyalonema sieboldi, a typical member of the Hyalonematidae family.
    Figure 1: Marine glass sponge Hyalonema sieboldi, a typical member of the Hyalonematidae family.

    a, Image of marine glass sponge Hyalonema sieboldi. Anchoring spicules of these sponges (b) have a multilayered structure and are organized according to the principle of ‘cylinder in cylinder’ (c). d, Fibrillar protein of a collagenous nature was isolated from the spicules using gentle desilicification in alkaline solution.

  2. Analysis of the isolated spicular organic matrix.
    Figure 2: Analysis of the isolated spicular organic matrix.

    a, SEM image of the nanofibrils observed in alkali extracts obtained after gentle demineralization over 14 days at 37 °C. b, Extracted ion chromatogram for the N2-(5-fluoro-2,4-dinitrophenyl)-L-valine amide (FDVA) derivatives at m/z 412 (Hyp, Leu, Ile) and m/z 396 (Pro) from the hydrolysate of the organic matrix of demineralized H. sieboldi spiculae. cps, counts per second. c, Relative amounts of all three Hyp-isomers and the Pro/Hyp ratio based on the signal intensities shown in b. The table summarizes the data for the amino-acid analysis, which provides the amount of each amino acid (g or mol). As all amino acids represent isomers with identical mass, the percentage represents the content of each Hyp residue in collagen.

  3. HR-TEM images of silicification on H. sieboldii collagen.
    Figure 3: HR-TEM images of silicification on H. sieboldii collagen.

    Silicification is apparent as nanoparticles after exposure of nanofibrillar H. sieboldii spicular collagen (a) to a solution of sodium methasilicate solution for 30 min. b, However, after protection of 3- and 4-hydroxyproline residues by ketal groups (Supplementary Figs S11 and S13), there is no visible silica deposition. c, Cleavage of the ketal protecting groups from collagen leads to a functional recovery with respect to silicification. d, The layer of silica nanoparticles is formed around the nanofibril of native spicular collagen during the first 30 min of silicification, as seen in the native collagen fibre (Supplementary Fig. S16). e, The results are in good agreement with measurements of activity (Supplementary Fig. S10) for non-protected collagen (filled triangle), which is lost following protection (filled diamonds), and partially restored when this protection is removed (filled circles).


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Author information


  1. Institute of Bioanalytical Chemistry, Dresden University of Technology, D-01062 Dresden, Germany

    • Hermann Ehrlich,
    • Eike Brunner,
    • Denis Kurek,
    • Vasily V. Bazhenov &
    • Sebastian Hunoldt
  2. Institute for Biochemistry, Genetic and Microbiology, University of Regensburg, 93053 Regensburg, Germany

    • Rainer Deutzmann
  3. BioArCh, Department of Biology, University of York, Heslington, York, YO10 5YW, UK

    • Enrico Cappellini,
    • Hannah Koon,
    • Caroline Solazzo,
    • Yue Yang &
    • Matthew J. Collins
  4. Technology Facility, Department of Biology, University of York, Heslington, York YO10 5YW, UK

    • David Ashford
  5. Centre of Excellence in Mass Spectrometry, University of York, Heslington, York YO10 5DD, UK

    • David Ashford &
    • Jane Thomas-Oates
  6. Department of Chemistry, University of York, Heslington, York YO10 5DD, UK

    • Jane Thomas-Oates
  7. Bruker Daltonik GmbH, Fahrenheitstrasse 4, 28359 Bremen, Germany

    • Markus Lubeck &
    • Carsten Baessmann
  8. Institute of Bioanalytical Chemistry, Center for Biotechnology and Biomedicine (BBZ), Universität Leipzig, D-014103 Leipzig, Germany

    • Tobias Langrock &
    • Ralf Hoffmann
  9. Department für Geo- und Umweltwissenschaften & GeoBio-CenterLMU, Ludwig-Maximilians-Universität, D-80333 München, Germany

    • Gert Wörheide
  10. Department of Geobiology, University of Göttingen, D-37077 Göttingen, Germany

    • Joachim Reitner
  11. Max Planck Institute of Chemical Physics of Solids, D-01187, Dresden, Germany

    • Paul Simon
  12. Leibniz Institute of Polymer Research Dresden and Max Bergmann Center of Biomaterials, D-01005 Dresden, Germany

    • Mikhail Tsurkan
  13. Centre d'Oceanologie de Marseille, Station marine d'Endoume, Aix-Marseille Universite–CNRS UMR 6540-DIMAR, 13007 Marseille, France

    • Aleksander V. Ereskovsky
  14. St. Petersburg State University, 199034 St. Petersburg, Russia

    • Aleksander V. Ereskovsky
  15. Centre ‘Bioengineering’ Russian Academy of Sciences, 117312 Moscow, Russia

    • Denis Kurek
  16. Institute of Chemistry and Applied Ecology, Far Eastern National University, 690650 Vladivostok, Russia

    • Vasily V. Bazhenov
  17. Max-Bergmann Center of Biomaterials and Institute of Materials Science, Dresden University of Technology, D- 01069 Dresden, Germany

    • Michael Mertig &
    • Hartmut Worch
  18. Institute of Solid State Physics, Dresden University of Technology, D- 01069 Dresden, Germany

    • Denis V. Vyalikh,
    • Serguei L. Molodtsov &
    • Kurt Kummer
  19. European XFEL GmbH, 22761 Hamburg, Germany

    • Denis V. Vyalikh,
    • Serguei L. Molodtsov &
    • Kurt Kummer
  20. Alfred Wegener Institute for Polar and Marine Research, D-27570 Bremerhaven, Germany

    • Victor Smetacek


All authors contributed to the design or execution of experiments, or analysed data. H.E. supervised the experiments, carried out demineralization experiments, performed collagen isolation, and wrote the manuscript. P.S. performed SEM and HRTEM, and prepared figures. A.E. collected, prepared and identified sponge samples and contributed to writing the manuscript. M.M., D.V.V., K.K. and S.L.M. performed NEXAFS experiments and designed figures. M.T. and V.V.B. carried out collagen modification. S.H. performed FTIR and prepared figures. E.B. performed NMR. R.D. performed Edman degradation and R.H. and T.L. performed amino acid analysis and mass spectrometry. M.C., H.K., C.S., Y.Y., E.C., D.A., M.L., C.B. and J.T.-O. were involved in acquiring and interpreting the mass spectrometric data, and M.C., H.K., E.C., D.A. and J.T.-O contributed to the writing of the manuscript. H.W., M.C., H.E., G.W., J.R., V.S. and E.B. analysed the results with regard to evolutionary implications and mechanisms of biomineralization, designed concepts, and wrote the manuscript.

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