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Chytridiomycosis, an infectious disease caused by the skin fungus, Batrachochytrium dendrobatidis (Bd), is a major contributor of declining amphibian populations over the past thirty years. The fungus disrupts the ion exchange on the frog skin leading to decreased body mass, righting reflex, and locomotor performance. However, the physiological mechanisms directly impacting locomotor performance are unknown. Given the negative effects on locomotor function and movement in infected species, it is hypothesized that the fungus produces a neurotoxin during its lifecycle. This study aims to determine the potential neurotoxicity and the equivalent dosage of Bd supernatant leading to locomotor decline in an aquatic frog, Xenopus laevis. Although Xenopus are highly resistant to the effects of Bd, previous literature has provided a dosage that induces mortality, which serves as a baseline to test concentration and neurotoxicity. Frogs were injected with Bd supernatant with comparable cell counts to a mortality inducing dosage. After four hours, frogs were filmed performing an escape response with high-speed cameras. The film was digitized in MatLab using a DLT Dataviewer script to determine escape velocity. Changes in locomotor performance when compared to previous literature may provide further insight into the mechanisms affecting neuromuscular performance of infected Xenopus laevis. [ABSTRACT FROM AUTHOR]

Batrachochytrium dendrobatidis (Bd) is a chytrid fungus that infects amphibians and is present in habitats worldwide. Bd chytridiomycosis has been documented in wild lesser sirens (Siren intermedia) and some greater sirens (Siren lacertina) were positive for Bd upon arrival at the Gray-Miller Amphibian Disease Lab at the University of Tennessee, Knoxville. This study evaluated the efficacy and safety of an anti-fungal drug (terbinafine) along with a novel delivery method, a terbinafine-impregnated intracoelomic implant (Melatek LLC), in prevention and clearance of Bd infection in greater sirens. Four sirens received terbinafine implants and four received blank implants. The animals were anesthetized with benzocaine water baths, and implants were placed intracoelomically through a small incision. The sirens were exposed to Bd zoospores at one- and two-months post-implant placement. Blood was collected from the ventral caudal tail vein monthly for plasma terbinafine levels, and skin swabs performed weekly for Bd qPCR at the Gray-Miller lab. Animals with terbinafine implants showed increased levels of terbinafine in plasma; however, treatment did not prevent infection and the clearance rate of Bd infection was not different from control animals. These findings indicate that intracoelomic drug implants are a safe method for antifungal drug delivery in amphibians; however, terbinafine efficacy in preventing chytridiomycosis remains unclear. [ABSTRACT FROM AUTHOR]

Chytridiomycosis is an emerging fungal disease of amphibians responsible for mass mortalities and population declines worldwide. To date, the presence and epidemiology of this pathogen in China is unclear. In order to assess the infection of wild anurans (Rana dybowskii) by the causative agent, Batrachochytrium dendrobatidis, 120 tadpoles were collected across 12 sites in Heilongjiang Province and examined using PCR assays. Jaw sheaths and tooth rows of tadpoles were checked by a 10× hand lens for visible signs of infection. No visible signs of infection were noted and all individuals were negative for B. dendrobatidis by PCR assay. This study is the first investigation of B. dendrobatidis in the tadpoles of free-ranging Rana dybowskii in Heilongjiang province. [ABSTRACT FROM PUBLISHER]