An extract of Hydrilla verticillata and associated epiphytes induces avian vacuolar myelinopathy in laboratory mallards.
Avian vacuolar myelinopathy (AVM) is a neurological disease affecting bald eagles (Haliaeetus leucocephalus), American coots (Fulica americana), waterfowl, and other birds in the southeastern United States. The cause of the disease is unknown, but is thought to be a naturally produced toxin. AVM is associated with aquatic macrophytes, most frequently hydrilla (Hydrilla verticillata), and researchers have linked the disease to an epiphytic cyanobacterial species associated with the macrophytes. The goal of this study was to develop an extraction protocol for separating the putative toxin from a hydrilla-cyanobacterial matrix. Hydrilla samples were collected from an AVM-affected reservoir (J. Strom Thurmond Lake, SC) and confirmed to contain the etiologic agent by mallard (Anas platyrhynchos) bioassay. These samples were then extracted using a solvent series of increasing polarity: hexanes, acetone, and methanol. Control hydrilla samples from a reference reservoir with no history of AVM (Lake Marion, SC) were extracted in parallel. Resulting extracts were administered to mallards by oral gavage. Our findings indicate that the methanol extracts of hydrilla collected from the AVM-affected site induced the disease in laboratory mallards. This study provides the first data documenting for an "extractable" AVM-inducing agent.
Wiley
Faith E
FE
Department of Forestry and Natural Resources, Clemson University, South Carolina 29634, USA. fwiley@aug.edu
Twiner
Michael J
MJ
Leighfield
Tod A
TA
Wilde
Susan B
SB
Van Dolah
Frances M
FM
Fischer
John R
JR
Bowerman
William W
WW
D000818:Animals; D001715:Bird Diseases / Q000139:chemically induced* / Q000473:pathology; D004372:Ducks; D004784:Environmental Monitoring; D031321:Hydrocharitaceae / Q000633:toxicity*; D009186:Myelin Sheath / Q000473:pathology; D020258:Neurotoxicity Syndromes / Q000209:etiology / Q000473:pathology / Q000662:veterinary*; D009498:Neurotoxins / Q000302:isolation & purification* / Q000633:toxicity; D009899:Optic Lobe, Nonmammalian / Q000473:pathology; D010936:Plant Extracts / Q000633:toxicity; D052616:Solid Phase Extraction / Q000379:methods*; D012997:Solvents; D018675:Toxicity Tests; D014617:Vacuoles / Q000187:drug effects
D009498:Neurotoxins; D010936:Plant Extracts; D012997:Solvents