Primers used to detect nAChR subunits.

Primer pairs were designed with the use of PubMed’s “Primer-blast” tool (http://www.ncbi.nlm.nih.gov/tools/primer-blast/). For each pair, forward and reverse primers were specific to different exons, so that potential DNA contamination could be ruled out. The optimal annealing temperature (Tm) was determined empirically with the use of a temperature gradient thermocycler, while maintaining high stringency conditions. PCR products for each primer pair were sequenced in order to ensure the accuracy of our results.