Expression of Ds-defensin mRNA in ticks. (A) Expression of Ds-defensin in tick salivary gland (SG) and midgut (MG) as determined by RT-PCR. Tick actin gene was amplified as the loading control. (B) Relative expression level of Ds-defensin in SG, MG, and whole ticks, as determined by quantitative RT-PCR. The copy number of Ds-defensin was normalized to tick actin. Results are expressed as the mean + SEM. Results represent at least three independent experiments.