Fig. 1: Gut-derived Tk affects selective appetite by increasing sugar intake and suppressing protein consumption in mated female flies.
From: Protein-responsive gut hormone tachykinin directs food choice and impacts lifespan
a, Intake of sugar and yeast over a 1-h dye-feeding assay for flies previously fed a sugar or yeast diet for 15 h (two-tailed unpaired Student’s t-test). b–d, Dye-feeding intake of sugar (b, 1 h), yeast (c, 1 h) and coconut oil (d, 4 h) after 15 h of yeast feeding (Kruskal–Wallis with Dunnett’s test). Sh, short-hairpin RNAi collection; KK, long-hairpin phiC31 RNAi collection, both from the Vienna Drosophila Resource Center. e, Representative confocal images of UAS-mCD8::GFP (GFP) expression in the midgut and brain driven by Tk::2A::GAL4 either alone (Tk>) or in combination with the pan-neuronal GAL4 inhibitor R57C10-GAL80 (thus Tkgut>). The mean number of GFP+ cells ±s.e.m. in each region (R1 + R2. R4, R4 and R5) is noted (n = 7–8 guts). Scale bars, 200 µm (midgut) and 50 µm (brain). f, Tk transcripts in dissected midguts and the central nervous systems (CNS) of Tkgut> and Tkgut>Tk-RNAi flies (two-tailed unpaired Student’s t-test). g, Six-hour CAFÉ assay for sugar intake in Tkgut>TkRNAi animals (Kruskal–Wallis with Dunn’s test). h, Twenty-two-hour FLIC assay for sugar-feeding behaviour of Tkgut>TkRNAi flies (one-way ANOVA with Dunnett’s test). i–l, Total ‘sips’ from sugar (i), yeast (j), lipid-depleted yeast (k) and mixed amino acid (l) media measured by the 1-h flyPAD assay (two-tailed Mann–Whitney U-tests). m, Preference index for yeast over sugar in the two-choice flyPAD assay following 15 h of being fed a yeast diet (two-tailed Mann–Whitney U-test). n, Two-hour yeast intake in a dye assay with TrpA1 activation of Tk+ EECs, with and without simultaneous Tk-RNAi (one-way ANOVA with Dunnett’s test). o, Model summarizing gut-derived Tk regulation of sugar and protein intake. Sample sizes (n) and P values are indicated in each plot. In a–d,g–n, n represents animals per group. In f, n represents central nervous system or midgut samples. Behavioural experiments were performed following 15 h of yeast feeding unless otherwise stated. Box plots show the median, the bounds of the box (25th and 75th percentiles) and whiskers representing minimum and maximum values. Dot plots in f,h include mean ± s.e.m., whereas plots in i–m indicate the median and 95% confidence interval. NS, not significant (P > 0.05).
