Larval preference for ribose and RNA is not mediated by sugar <i>Gr</i> genes.

<p><b>Two-choice preference assays for arabinose, ribose, deoxyribose, and RNA (panel a and c) and survival on these chemicals and nutritious sugars (panel b).</b> (a) Preference for arabinose is independent on various sugar <i>Gr</i> genes (<i>n</i> = 12–28). The underlying data can be found in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.2005570#pbio.2005570.s005" target="_blank">S1 Data</a>. (b) Comparison of survival of <i>w</i>^<i>1118</i> larvae when kept on different substrates (<i>n</i> = 3–8). After 72 hours, approximately 50% of the larvae survive on agarose-only substrate (median survival, dashed line). For simplicity, significant differences are only indicated for median survival time. Data are represented as mean ± SEM. “*” represents significant difference between the larval survival on different substrates and agarose (two-tailed Mann-Whitney U test, <i>p</i> < 0.05). Reduced survival rate of larvae kept on arabinose and deoxyribose might be due to interference of these chemicals with sugar metabolism. The underlying data can be found in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.2005570#pbio.2005570.s006" target="_blank">S2 Data</a>. (c) Larvae show strong preference for ribose (n = 12–36) and RNA (n = 6–36) when lacking <i>Gr43a</i> or the 8 <i>sGr</i>. Larvae are not attracted to deoxyribose (n = 6–24). As for fructose [<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.2005570#pbio.2005570.ref004" target="_blank">4</a>], Δ<i>sGr</i> larvae showed stronger preference for ribose than wild-type larvae. Concentration of all substrates was 100 mM in 1% agarose, except RNA (0.5 mg/mL in 1% agarose). Genotypes: <i>w</i>^<i>1118</i> (control), <i>w</i>^<i>1118</i><i>; Gr43a</i>^<i>GAL4</i><i>/Gr43a</i>^{<i>GAL 4</i>}<i>(</i>Δ<i>Gr43a</i>), and <i>w</i>^<i>1118</i>; Δ<i>Gr61a</i> Δ<i>Gr64a-f/</i>Δ<i>Gr61a</i> Δ<i>Gr64a-f (</i>Δ<i>sGrs</i>). The underlying data can be found in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.2005570#pbio.2005570.s005" target="_blank">S1 Data</a>. Gr, gustatory receptor; PREF, preference index; <i>sGr</i>, sugar <i>Gr</i> gene.