Fig. 3. nur encodes an antimicrobial peptide that promotes survival upon expression in neurons.

(A) Alignment between NUR and a fish cathelicidin. The C-terminal domain of NUR shows sequence similarity with a Greenland cod (Gadus ogac) cathelicidin. Note the overlap of glycine and arginine residues, indicated by asterisks. Amino acid abbreviations: A, Ala; D, Asp; E, Glu; G, Gly; I, Ile; K, Lys; L, Leu; R, Arg; S, Ser; T, Thr; V, Val. (B) Top: Alamar Blue cell viability assay; S. marcescens in PBS alone (center), with kanamycin (left), or with NUR protein (right). Blue color indicates lack of bacteria. Bottom: The assay was quantified by measuring absorbance at 595 nm (n = 3). ***P < 0.001 (Student t test). Error bars denote SEM. (C) Kaplan-Meier plot depicting survival of infection with S. marcescens in nur-overexpressing flies (+RU486) and controls (−RU486); n = 68 and 74 females, respectively. *P < 0.02 (log rank test). (D) Daytime sleep in nur-overexpressing flies (black) and controls (blue) after infection at ZT18 the previous night; n = 49 control and 62 +RU486-fed female flies, respectively. Median ± interquartile is shown. ****P < 0.0001 (Mann-Whitney U test). Note that daytime sleep values are lower than in other figures (fig. S1B). This effect was also observed in uninfected controls and may be caused by the CO₂ anesthesia necessary for infecting flies. (E) Bacterial load in control flies (−) and nur overexpressors (+) at indicated times after infection; n = 9 for each. Median ± interquartile is shown; cfu, colony-forming units. *P < 0.05 (Mann-Whitney U test).