RP9 Terrestrial Ecotoxicology
Thursday, 17 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(WIL-1117-821122) Development of an extraction method and in vitro bioassay for the putative AVM toxin.

Wiley, F^{1, 2}, Twiner, M², Van Dolah, F², Bowerman, W¹, Wilde, S³, Leighfield, T², ¹ Clemson University, Pendleton, SC, USA² NOAA-National Ocean Service, Charleston, SC, USA³ South Carolina Department of Natural Resources, Charleston, SC, USA

ABSTRACT- Avian vacuolar myelinopathy (AVM), a neurological disease of unknown origin, has been linked to ingestion of nuisance aquatic vegetation. The pathology and nature of AVM epornitics suggest a toxin as the causative agent, and the working hypothesis is that a species of epiphytic cyanobacteria associated with the vegetation is the source of this putative toxin. The purpose of this project is to develop a method for putative toxin extraction, as well as develop a rapid and sensitive in vitro assay capable of toxin detection, which can then be used to guide toxin fractionation and isolation studies. Samples of aquatic vegetation (Hydrilla verticillata and associated epiphytes) were collected and confirmed as either positive or negative for the putative AVM toxin by mallard (Anas platyrhynchos) bioassay. Equivalent amounts of positive and negative (control) vegetation are now being processed using a solvent extraction series of increasing polarity (hexane, acetone, methanol, water). Each resulting fraction will be tested for the presence of AVM toxin by mallard bioassay, as well as screened for cytotoxicity using several cell lines. Preliminary cell line results reveal cytotoxicity associated with the non-polar hexane fraction of the AVM-positive vegetation, as well as the acetone and methanol fractions of both AVM-positive and AVM-negative vegetation. The extracts require confirmation by mallard bioassay before hypothesizing a link between cytotoxicity and a putative AVM toxin.

Key words: avian, avm, cyanobacteria, wildlife