Metal tolerance in brown trout
Metal tolerance in brown trout
Brown trout were sampled from one clean catchment (River Fowey; metal-sensitive fish) and one metal-impacted catchment (River Hayle; metal-tolerant fish) and were transported to the Aquatic Resources Centre (ARC), University of Exeter. Fish were maintained in 39 L tanks for the depuration and exposure phases. The sub-lethal exposure comprised a metal mixture similar to that found in the River Hayle, at values estimated to be 10-15% of the lethal concentration 50 (LC50) for salmonids: Cd 0.4 μg/L; Cu 3 μg/L; Ni 10 μg/L and Zn 75 μg/L. Because water chemistry features are strong determinants of the bioavailability of metals, we created synthetic freshwater in the laboratory mimicking chemistry of the River Hayle, using salts of the following concentrations: NaCl 22.9 mg/L; KHCO3 12.8 mg/L; MgSO4 123.2 mg/L and Ca(NO3)2 100.4 mg.L. Liver and gill tissue were weighed, homogenised in Extraction Buffer, and RNA was extracted using Qiagen RNA-seq extraction kits following the manufacturers' protocol, including an on-column DNAse digestion step.  Libraries were prepared following the TruSeq Stranded mRNA library preparation protocol (Illumina).