Sequences of gene-specific primers were qFw: 5′-CGTCCCTGCCCTTTGTACAC-3′ and qRv: 5′-CGAACACTTCACCGGACCAT-3′ for 18S rRNA (Noguchi et al., 2008), and qFw: 5′-CGCGGAAGACGGATGAGT-3′ and qRv: 5′-GATTCCTGCAACGAAAGCAAA-3′ for CYP81Q1, designed by the Primer Express 3.0 program (Life Technologies). Levels of CYP81Q1 gene expression were quantified relative to the reference gene 18S rRNA, and expressed as ratios relative to a control value, using the 2−ΔΔCt method ( Livak and Schmittgen, 2001).