Overview of P. aquilinum transcriptome sequencing and assembly. (A) A histogram of the filter passed and adapter/quality trimmed Roche 454 GS-FLX Titanium read lengths. (B) A histogram of unigene lengths for the final unigene set after the 2-step assembly. Note that the longest unigene is 4,489 bp and the x-axis has been truncated at 3 kb. (C) A histogram of the average read-depth coverage for unigenes. The steep decline in coverage observed here is typical of normalized libraries . Coverage values between 30× and 1800× have been binned (see the vertical axis in Figure 1D). (D) A density scatterplot showing the relationship between unigene length and coverage. Points with a higher local density are darker.