Amphibian diversity has suffered substantial loss over the last several decades. Much of this loss in diversity can be attributed to chytrid fungal pathogens in the genus Batrachochytrium, the causal agents of a deadly, cutaneous disease known as chytridiomycosis. Chemists have more recently collaborated with disease ecologists to examine bacterial secondary metabolites, identifying antifungal compounds endemic to amphibian skin, including violacein and indole-3-carboxyaldehyde. Another metabolite of recent interest has been the highly neurotoxic Na+ pump inhibitor, tetrodotoxin (TTX). Isolated from newt skin, TTX has previously been determined to deter vertebrate predators and is mysteriously negatively correlated with likelihood of infection with the fungal skin pathogen Batrachochytrium dendrobatidis and with parasite richness overall. Aside from its defensive role, little is known about the biosynthetic origin of TTX in newts, and it is unclear whether it is endogenously or exogenously produced, and if its production is correlated with or triggered by a cascade of stress hormones including cortisol and corticosterone. Determining a correlation between TTX, stress hormones, and parasitic or microbial colonizers could provide clues about TTX’s enigmatic origin. To address this, we developed a rapid normal phase LC-MS/MS method to identify TTX from biological samples and a complementary reverse phase LC-MS/MS method to validate quantification of cortisol and corticosterone; field sample testing is also being pursued.

Tetrodotoxin production and stress response in newts as analyzed by LC-MS

2019 Spring National Meeting

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