Total RNA was isolated by use of an RNA purification system (PureLink Microto-Midi Total RNA Purification System; Invitrogen, Carlsbad, CA). RNA (1 μg) was reverse transcribed by first-strand synthesis (SuperScript III First-Strand Synthesis System for RT-PCR; Invitrogen). For PCR amplification, 1 μL cDNA was denatured for 5 minutes at 94°C, then for 26 cycles for CO1 and NADPH-1 and 28 cycles for ATPsynβ. Each cycle included 1-minute denaturation at 94°C, 40-second primer annealing at 50°C for CO1, 60°C for NADPH-1, and 58.2°C for ATPsynβ, then 1-minute polymerization at 72°C. Primer sequences were as follows: NADPH-1 forward, 5′-GGCCCCAACGTGGTAGGC; NADPH-1 reverse, 5′-GTCGTAGCGGAATCGGGG; CO1 forward, 5′-TCCATAACGCTCCTCATACT; CO1 reverse: 5′-GTGGTAAAAGGCTCAGAAAA; ATPsynβ forward, 5′-TCTCCTTCGCCAAAAGCAGG; ATPsynβ reverse, 5′-TGTTTGGTTTTGATGGGACC; β-actin(Actb) forward, 5′-CTACAATGAGCTGCGTGTGG; and β-actin reverse, 5′-CGGTGAGGATCTTCATGAGG. RT-PCR products were 745, 233, 335, and 314 bp, respectively.