Fig. 4

Bacterial infection suppresses reduced piRNA levels at 25 °C. a Expression of GFP in nuclei of the gonad (G), oocytes (Oo) and eggs (E) of animals carrying the piRNA sensor in the wild-type strain (WT, left) and in the prde-1 mutant (prde-1 right) both grown from hatching either at 20 °C or 25 °C on regular bacteria (HB101) or at 25 °C on the pathogenic bacteria Serratia marcescens (DB11). b Proportion of wild-type animals (WT) and prde-1 animals expressing GFP on: P. aeruginosa (purple) PA14 (high toxicity, n = 47) and PAK (low toxicity, n = 73); S. marcescens DB11 (red, n = 106); and P. luminescens (yellow; WT n = 31; prg-1 n = 28; prde-1 n = 46) relative to the proportion of GFP-positive animals grown at 25 °C on regular food (n = 38). Fisher’s exact test was used to evaluate differences between conditions. Raw data are available in Additional file 9: Table S4. c Change (Log₂) in mature piRNA levels in F1s from parents grown at 20 °C (P0 at 20 °C) or grown at 25 °C (P0 at 25 °C) in presence of Serratia marcescens compared to F1s from parents grown at 25 °C. d, e Changes (Log₂) in gene expression in F1s from infected P0s compared to F1s from P0s grown at 25 °C (left) and F1s from P0s grown at 25 °C compared to F1s from P0s grown at 25 °C (right) for: (d) genes previously identified as intergenerationally upregulated when parents grown at 25 °C; (e) genes intergenerationally upregulated both when parents were grown at 25 °C and in the prde-1 mutant