Environmental Futures Centre, School of Environment, Griffith University, Gold Coast Campus, QLD 4222, Australia.
Comp Biochem Physiol A Mol Integr Physiol. 2012 Jul;162(3):171-6. doi: 10.1016/j.cbpa.2012.02.018. Epub 2012 Feb 22.
The emerging amphibian disease chytridiomycosis, which is caused by the fungal pathogen (Batrachochytrium dendrobatidis, Bd), has caused mass mortalities of native amphibian populations globally. There have been no previous studies on the relationships between stress hormones in free-living amphibians and Bd infections. In this study, we measured urinary corticosterone metabolite concentrations and Bd infections within free-living populations of male Stony Creek frog (Litoria wilcoxii) in Queensland, Australia. Prevalence of Bd zoospores from frog skin swabs was quantified using a real-time quantitative PCR technique. A urinary corticosterone enzyme-immunoassay (EIA) was validated using adrenocorticotropic hormone (ACTH) challenge. Urinary corticosterone concentrations of male frogs increased within 1-2 days after ACTH challenge and returned to baseline levels within 3 days post-ACTH injection. None of the frogs showed any rise in urinary corticosterone after saline injections. Individual male frogs showed either low or high baseline corticosterone concentrations. Male frogs identified as positive for Bd infection had significantly higher baseline urinary corticosterone concentrations in comparison to Bd negative male frogs. Urinary corticosterone EIA provides a reliable indication of stress in this frog species and this non-invasive physiological tool can be used to further assess the dynamics of Bd infections and physiological stress responses in other native amphibians.
新兴的两栖动物疾病蛙壶菌病（chytridiomycosis），由真菌病原体（Batrachochytrium dendrobatidis，Bd）引起，已在全球范围内导致了大量本地两栖动物种群的死亡。以前没有研究过自由生活的两栖动物中的应激激素与 Bd 感染之间的关系。在这项研究中，我们在澳大利亚昆士兰州的自由生活的石溪蛙（Litoria wilcoxii）雄性种群中测量了尿皮质酮代谢物浓度和 Bd 感染。使用实时定量 PCR 技术定量了从蛙皮拭子中分离出的 Bd 游动孢子的流行率。使用促肾上腺皮质激素（ACTH）挑战验证了尿皮质酮酶免疫分析（EIA）。在 ACTH 挑战后 1-2 天内，雄性青蛙的尿皮质酮浓度增加，并在 ACTH 注射后 3 天内恢复到基线水平。盐水注射后，没有一只青蛙的尿皮质酮水平升高。个体雄性青蛙的基础皮质酮浓度要么很低，要么很高。与 Bd 阴性雄性青蛙相比，Bd 感染阳性的雄性青蛙的基础尿皮质酮浓度显著更高。尿皮质酮 EIA 为该蛙种的应激提供了可靠的指示，这种非侵入性生理工具可用于进一步评估其他本地两栖动物中 Bd 感染和生理应激反应的动态。
