Gene Expression in An. gambiae Female Antennae vs. Bodies. Volcano plot showing the relative expression levels of genes in female whole bodies versus female antennae. The x-axis represents the log2 of the expression ratio (antennae RPKM: bodies RPKM) for each gene of the An. gambiae transcriptome. The y-axis represents the negative log10 of the p-value of Fisher's Exact test. Black data points (n = 2201) represent genes that were both statistically significant (red horizontal line; p< 3.9 × 10-6) and biologically significant (red vertical lines; greater than 2-fold difference in RPKMs). Gray data points (n = 10603) represent genes that fell outside one or both of these significance criteria. Red data points indicate the expression values of major chemosensory genes (AgOrs, AgIrs, AgGrs, and AgObps) that were statistically significant and >2-fold enhanced. RPKM values of 0.00 were transformed to 0.10 prior to calculating antennae:bodies ratios, such that those genes could also be represented on the plot.