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Figure 2 | BMC Genomics

Figure 2

From: Sex- and tissue-specific profiles of chemosensory gene expression in a herbivorous gall-inducing fly (Diptera: Cecidomyiidae)

Figure 2

Comparison of expression profiles of the 228 chemosensory genes. Expression level profiles of the 228 genes involved in olfaction or taste in the four tissues were compared using (A) Jensen-Shannon (JS) distance, and (B) principle component analysis. In contrast to the global analysis (Figure 1), the female and male terminal abdomen tissues had the most similar expression profiles, whereas the male and female antennae were more different from each other. In (B), PC 1 and PC 2 explained 66.0% and 20.1% respectively of the overall expression level variation among the chemosensory genes in the four tissues. Both the direction and length (length = within-transcriptome variation) of the eigenvectors (red arrows) indicate that the chemosensory genes (black dots) in the male and female terminal abdominal tissues had highly similar variation in expression levels, both in relation to PC 1 and PC 2. In contrast, the variation in expression levels differed between the male and female antennae, and these tissues were also different from the terminal abdominal tissues (as indicated by differences in length and direction of the eigenvectors). The difference in expression of the chemosensory genes between the four tissues was explained (mainly) by the variation encompassed by PC 2 (i.e. as shown by the position of the four arrow heads). In addition, 1:1 plots (dashed line = 1:1 relationship) in combination with linear regression analyses (blue solid lines) indicate an overall up-regulation of expression of the 228 genes in the antennae of both sexes, compared to the female (C) or male terminal abdomen (D), respectively. The antennae of males and females expressed many of these genes differently (E). Overall, the female and male terminal abdomen had low expression of these genes and the expression was closer to a 1:1 relationship than in the other pair-wise comparisons (F).

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