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Naturwissenschaften

, Volume 88, Issue 4, pp 179–182 | Cite as

Changes in element composition along the spinning duct in a Nephila spider

  • David P. Knight
  • Fritz Vollrath
Short Communication

Abstract.

The silk gland of the golden orb spider Nephila edulis connects to the exit spigot through a long S-shaped duct that assists in the formation of the thread. Previous evidence suggests that the epithelium of the distal (last) part of the duct is specialized for ion transport and that a proton pump is involved in this process. Here, we present evidence from SEM (scanning electron microscope)-EDAX (energy dispersive X-ray) microanalysis of rapidly frozen material maintained at approximately –150°C and from the use of pH indicators that the element composition and pH change progressively as the dragline silk dope (spinning solution) passes down the duct to form the thread. Na+ and Cl composition decreased while K+ and P and S increased. Indicators suggested that the pH dropped from 6.9±0.1 to 6.3±0.1. These novel findings suggest that the absorption of Na+ and secretion of the more chaotropic K+ may help the silk protein molecules to refold while the secretion of H+ may assist in this process and reduce the repulsive charges on them. This in turn may allow the molecules to approach one another more closely to crystallize. Thus precise control of the ionic environment within the spider's spinning duct may be important in forming a tough insoluble thread and when devising mimetic processes to spin silk proteins industrially.

Keywords

Proton Pump Protein Molecule Element Composition Precise Control Previous Evidence 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  • David P. Knight
    • 1
  • Fritz Vollrath
    • 1
  1. 1.Zoology Department, University of Oxford, South Parks Road, Oxford OX1 3PS, UK

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