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Composite Microstructure of Spider (Nephila Clavipes) Dragline

Published online by Cambridge University Press:  15 February 2011

Brad Thiel ,
Dennis Kunkel ,
Keith Guess  and
Christopher Viney
Brad Thiel
Affiliation:
Department of Materials Science and Engineering FB-10
Dennis Kunkel
Affiliation:
Department of Neurological Surgery RI-20
Keith Guess
Affiliation:
Molecular Bioengineering Program, Center for Bioengineering WD-12, University of Washington, Seattle, WA 98195, USA
Christopher Viney
Affiliation:
Molecular Bioengineering Program, Center for Bioengineering WD-12, University of Washington, Seattle, WA 98195, USA
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Abstract

Dragline fibers collected at a controlled silking rate from Nephila clavipes spiders were studied by analytical transmission electron microscopy (TEM). The physical microstructure consists of irregularly-shaped ß-sheet crystallites (approx. 70–100 nm in diameter, and comprising approx. 50 volume per cent) in an amorphous matrix. Electron diffraction from single crystallites indicates an orthogonal unit cell with space group P21; the lattice parameters are a = 13.31 Å (inter-sheet repeat), b = 9.44 Å (inter-chain repeat within ß-sheets) and c = 20.88 Å (intra-chain repeat). The crystallites are not truly periodic structures having long range positional order, but are better described as non-periodic layered structures, similar to the ordered structures formed when liquid crystalline random copolymers solidify. Electron energy loss spectroscopy (EELS) reveals chemical microstructure in the fibers. The matrix contains bands (approx. 200 nm wide) of alternately higher and lower nitrogen content. This variation cannot be explained in terms of known protein domains alone, and may reflect the presence of retained small-molecule species from secretory granules. Calcium is localized uniquely to the crystallites (at a concentration of approx. one calcium atom per 120 amino acid residues, as measured by inductively coupled plasma spectroscopy). Varying the calcium content may be one mechanism by which the spider can tailor the evolution of the microstructure, and hence the physical properties of the silk fiber.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 330: Symposium S – Biomolecular Materials by Design , 1993 , 21
Copyright
Copyright © Materials Research Society 1994

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References

REFERENCES

1. Kaplan, D.L., Lombardi, S.J., Muller, W.S. and Fossey, S.A., in Biomaterials: Novel Materials from Biological Sources, edited by Byrom, D. (Stockton Press, New York, 1991) p. 3.Google Scholar
2. Kaplan, D.L., Fossey, S., Viney, C. and Muller, W., in Hierarchically Structured Materials, edited by Aksay, I.A., Baer, E., Sarikaya, M. and Tirrell, D.A. (Materials Research Society, Pittsburgh, 1992) p. 19.Google Scholar
3. Kaplan, D.L., Adams, W.W., Farmer, B.L. and Viney, C. (editors), Silk Polymers: Materials Science and Biotechnology (American Chemical Society, Washington, DC, 1994).Google Scholar
4. Xu, M. and Lewis, R.V., Proceedings of the National Academy of Sciences, USA 87, 7120 (1990).Google Scholar
5. Hinman, M.B. and Lewis, R.V., Journal of Biological Chemistry 267, 19320 (1992).Google Scholar
6. Kerkam, K., Viney, C., Kaplan, D.L. and Lombardi, S.J., Nature 349, 596 (1991).Google Scholar
7. Viney, C., Huber, A.E., Dunaway, D.L., Kerkam, K. and Case, S.T., in Silk Polymers: Materials Science and Biotechnology, edited by Kaplan, D.L., Adams, W.W., Farmer, B.L. and Viney, C. (American Chemical Society, Washington, DC, 1994) p. 120.Google Scholar
8. Warwicker, J.O., Journal of Molecular Biology 2, 350 (1960).Google Scholar
9. Gillespie, D.B., Viney, C. and Yager, P., in Silk Polymers: Materials Science and Biotechnology, edited by Kaplan, D.L., Adams, W.W., Farmer, B.L. and Viney, C. (American Chemical Society, Washington, DC, 1994) p. 155.Google Scholar
10. Gosline, J.M., DeMont, M.E. and Denny, M.W., Endeavour 10, 37 (1986).Google Scholar
11. Gosline, J.M., Shadwick, R.E., Demont, M.E. and Denny, M.W., in Biological and Synthetic Polymer Networks, edited by Kramer, O. (Elsevier, London, 1988) p. 57.CrossRefGoogle Scholar
12. Marsh, R.E., Corey, R.B. and Pauling, L., Biochimica et Biophysica Acta 16, 1 (1955).Google Scholar
13. Work, R.W. and Emerson, P.D., Journal of Arachnology 10, 1 (1982).Google Scholar
14. Luft, J.H., The Journal of Biophysical and Biochemical Cytology 9, 409 (1961).CrossRefGoogle Scholar
15. Egerton, R.F., Electron Energy-Loss Spectroscopy in the Electron Microscope (Plenum, New York, 1986).Google Scholar
16. Malis, T., Cheng, S.C. and Egerton, R.F., Journal of Electron Microscopy Technique 8, 193 (1988).Google Scholar
17. Hanna, S. and Windle, A.H., Polymer 29, 207 (1988).Google Scholar
18. Nye, J.F., Physical Properties of Crystals (Oxford University Press, Oxford, 1985).Google Scholar