Chemoecology

, Volume 22, Issue 3, pp 199–206

Chemical investigations of defensive steroid sequestration by the Asian snake Rhabdophis tigrinus

  • Deborah A. Hutchinson
  • Alan H. Savitzky
  • Akira Mori
  • Gordon M. Burghardt
  • Jerrold Meinwald
  • Frank C. Schroeder
Research Paper

DOI: 10.1007/s00049-011-0078-2

Cite this article as:
Hutchinson, D.A., Savitzky, A.H., Mori, A. et al. Chemoecology (2012) 22: 199. doi:10.1007/s00049-011-0078-2

Abstract

Rhabdophis tigrinus is an Asian natricine snake that possesses unusual defensive glands on the dorsal surface of its neck. These nuchal glands typically contain cardiotonic steroidal toxins known as bufadienolides, which are also abundant in the skin of toads. Feeding experiments demonstrated that toads consumed as prey are the ultimate sources of the bufadienolides in nuchal glands of R. tigrinus. Indeed, snakes on a toad-free Japanese island (Kinkasan, Miyagi Prefecture) lack these compounds in their nuchal glands, confirming that these snakes are unable to synthesize defensive bufadienolides. However, when snakes from Kinkasan are fed toads in the laboratory, they accumulate bufadienolides in their nuchal glands, indicating that they have not lost the ability to sequester defensive compounds from prey. In contrast, R. tigrinus from a toad-rich island (Ishima, Tokushima Prefecture) possess large quantities of bufadienolides, reflecting the abundance of toads from which these compounds can be sequestered. Feeding experiments involving gravid R. tigrinus demonstrated that bufadienolides can be provisioned to offspring so that hatchlings are chemically defended before their first toad meal. Maternal provisioning of bufadienolides can take place through two routes: by deposition in yolk and by diffusion in utero, even late in gestation. We applied bufadienolides to the surface of eggs from Kinkasan and found that the embryos are able to take up these compounds into their nuchal glands, demonstrating the feasibility of uptake across the eggshell. Female R. tigrinus provision bufadienolides to their offspring in direct proportion to their own level of chemical defense. By feeding toad-derived bufotoxins to R. tigrinus hatchlings, we determined that the sequestration of these compounds involves at least three types of modification: hydrolytic cleavage of suberylarginine side chains, hydroxylation, and epimerization.

Keywords

Dietary toxins Toad Bufadienolides Nuchal glands Antipredator defense 

Copyright information

© Springer Basel AG 2011

Authors and Affiliations

  • Deborah A. Hutchinson
    • 1
  • Alan H. Savitzky
    • 2
  • Akira Mori
    • 3
  • Gordon M. Burghardt
    • 4
    • 5
  • Jerrold Meinwald
    • 6
  • Frank C. Schroeder
    • 6
    • 7
  1. 1.Department of BiologyCoastal Carolina UniversityConwayUSA
  2. 2.Department of Biological SciencesOld Dominion UniversityNorfolkUSA
  3. 3.Department of Zoology, Graduate School of ScienceKyoto UniversityKyotoJapan
  4. 4.Department of PsychologyUniversity of TennesseeKnoxvilleUSA
  5. 5.Department of Ecology and Evolutionary BiologyUniversity of TennesseeKnoxvilleUSA
  6. 6.Department of Chemistry and Chemical BiologyCornell UniversityIthacaUSA
  7. 7.Boyce Thompson Institute, Cornell UniversityIthacaUSA

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