Project description:Comparison of pre and post metamorphis phases of cane toad Keywords: Developmental Stages Samples were harvested at 9, 18, 28 (pre-metamorph), 30 and 53 (post-metamorph) days of age and RNA extracted using Trizol Reagent (Invitrogen). Total RNA (100 mg) was reverse transcribed (Qiagen) and labelled cDNA probes were generated using the fluorophores, Cy3 and Cy5 (Amersham Pharmacia Biotech). Prehybridization of slides, application of the probe to the microarray slides, hybridisation, and subsequent washing steps were performed according to manufacturer's instructions (Corning Microarray Technology). Slides were scanned and analysed with a GenePix 4000B laser scanner and GenePix 3.0 and 4.0 software (Axon Instruments).
Project description:Boreal toads (Anaxyrus boreas boreas) of the Southern Rocky Mountain population are declining due to the introduction of the chytrid fungus Batrachochytrium dendrobatidis (Bd). Boreal toads in Colorado are generally susceptible to Bd infection, but some Bd-tolerant populations persist in parts of the Southern Rocky Mountain and broader Eastern boreal toad population. We conducted a Bd challenge with lab-reared sibling toads from Bd-susceptible Colorado and purportedly Bd-tolerant Utah populations and report on transcriptomic responses to Bd during late infection in skin and liver tissue. Fewer immune genes were expressed in response to Bd in Colorado toads, but with greater upregulation compared to Utah toads, indicating a dysregulated immune response. Signatures of Bd-tolerance in Utah toads included more moderate upregulation in immune gene expression and a significantly enriched suite of gene functions related to innate and adaptive immune responses. Our transcriptomic results support the notion that Utah toads are tolerant to Bd, rather than resistant, carrying Bd loads similar to Colorado yet having a unique transcriptomic profile and presenting minimal clinical signs of chytridiomycosis. We conclude that closely related populations have divergent transcriptomic responses to Bd with a dysregulated immune response in Bd-susceptible toads.