Fig 1. Larval preference for ribose and RNA is not mediated by sugar Gr genes.

Two-choice preference assays for arabinose, ribose, deoxyribose, and RNA (panel a and c) and survival on these chemicals and nutritious sugars (panel b). (a) Preference for arabinose is independent on various sugar Gr genes (n = 12–28). The underlying data can be found in S1 Data. (b) Comparison of survival of w¹¹¹⁸ larvae when kept on different substrates (n = 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, p < 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 S2 Data. (c) Larvae show strong preference for ribose (n = 12–36) and RNA (n = 6–36) when lacking Gr43a or the 8 sGr. Larvae are not attracted to deoxyribose (n = 6–24). As for fructose [4], ΔsGr 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: w¹¹¹⁸ (control), w¹¹¹⁸; Gr43a^GAL4/Gr43a^{GAL 4}(ΔGr43a), and w¹¹¹⁸; ΔGr61a ΔGr64a-f/ΔGr61a ΔGr64a-f (ΔsGrs). The underlying data can be found in S1 Data. Gr, gustatory receptor; PREF, preference index; sGr, sugar Gr gene.