Obp56h Modulates Mating Behavior in Drosophila melanogaster

Social interactions in insects are driven by conspecific chemical signals that are detected via olfactory and gustatory neurons. Odorant binding proteins (Obps) transport volatile odorants to chemosensory receptors, but their effects on behaviors remain poorly characterized. Here, we report that RNAi knockdown of Obp56h gene expression in Drosophila melanogaster enhances mating behavior by reducing courtship latency. The change in mating behavior that results from inhibition of Obp56h expression is accompanied by significant alterations in cuticular hydrocarbon (CHC) composition, including reduction in 5-tricosene (5-T), an inhibitory sex pheromone produced by males that increases copulation latency during courtship. Whole genome RNA sequencing confirms that expression of Obp56h is virtually abolished in Drosophila heads. Inhibition of Obp56h expression also affects expression of other chemoreception genes, including upregulation of lush in both sexes and Obp83ef in females, and reduction in expression of Obp19b and Or19b in males. In addition, several genes associated with lipid metabolism, which underlies the production of cuticular hydrocarbons, show altered transcript abundances. Our data show that modulation of mating behavior through reduction of Obp56h is accompanied by altered cuticular hydrocarbon profiles and implicate 5-T as a possible ligand for Obp56h

Functional analyses of candidate hub genes with human orthologs associated with resistance to lead and cadmium exposure of adult flies using RNAi targeted knockdown of gene expression.

<p>The bar graphs represent differences between the number of flies alive for RNAi lines and their corresponding controls on the seventh day of exposure to lead (A) or on the fifth day of exposure to cadmium (B). Bars above the horizontal line indicate increased susceptibility to heavy metal exposure, whereas bars below the horizontal line indicate increased resistance. Red bars indicate females and blue bars indicate males. Error bars denote standard errors. <i>P</i>-values are from the reduced ANOVA model. **: <i>P</i><0.01, *: <i>P</i><0.05. See also <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1006907#pgen.1006907.s016" target="_blank">S11 Table</a>.</p

SNPs and candidate genes associated with resistance to lead and cadmium exposure from extreme QTL analyses that passed the Bonferroni-corrected threshold (<i>P</i> < 1.896 x 10⁻⁸).

<p>SNPs and candidate genes associated with resistance to lead and cadmium exposure from extreme QTL analyses that passed the Bonferroni-corrected threshold (<i>P</i> < 1.896 x 10⁻⁸).</p

Biological function annotations of hub genes from human orthologous networks.

<p>Biological function annotations of hub genes from human orthologous networks.</p

Dose-response curves for survival of adult AIP flies exposed to lead acetate (top panels) or cadmium chloride (bottom panels).

<p>Dose-response curves for survival of adult AIP flies exposed to lead acetate (top panels) or cadmium chloride (bottom panels).</p

Network of human candidate genes orthologous to the Drosophila candidate genes shown in Fig 5.

<p>Orange edges indicate physical interactions and the green edge indicates a genetic interaction.</p

Extreme QTL mapping for variation in resistance to lead and cadmium exposure of adult flies.

<p>Manhattan plots show all SNPs significantly associated with resistance to lead or cadmium exposure at FDR<0.05. The <i>X</i>-axis designates the chromosomal arms of the Drosophila genome. SNPs are color coded. Blue dots indicate SNPs in or near a gene that harbors multiple significant SNPs (≥5), green dots indicate SNPs with large allele frequency differences between the resistant population and the control population (≥2 fold), and red dots indicate SNPs with large allele frequency differences in or near a gene that harbors multiple significant SNPs(≥5). The horizontal dashed lines indicate the Bonferroni-corrected threshold for statistical significance.</p

Networks derived from all candidate genes associated with heavy metal resistance that were in common between males and females or between lead and cadmium.

<p>Orange edges indicate physical interactions and green edges indicate genetic interactions.</p