Reported transgenerational responses to <i>Pseudomonas aeruginosa</i> in <i>Caenorhabditis elegans</i> are not robust.

Abstract

We report our attempt to replicate reports of transgenerational epigenetic inheritance in <i>Caenorhabditis elegans</i>. Multiple laboratories report that <i>C. elegans</i> adults and their F1 embryos exposed to the pathogen <i>Pseudomonas aeruginosa</i> show pathogen aversion behavior and increased <i>daf-7/TGFβ</i> reporter gene expression. However, results from one group show persistence of both through the F4 generation. We failed to consistently detect either the avoidance response or elevated <i>daf-7</i> expression beyond the F1 generation. We confirmed that the dsRNA transport proteins SID-1 and SID-2 are required for intergenerational (F1) inheritance of pathogen avoidance, but not for the F1 inheritance of elevated <i>daf-7</i> expression. Reanalysis of RNA seq data provides additional evidence that this intergenerational inherited PA14 response may be mediated by small RNAs. The experimental methods are well-described, the source materials are readily available, including samples from the reporting laboratory, and we explored a variety of environmental conditions likely to account for lab-to-lab variability. None of these adjustments altered our results. We conclude that this example of transgenerational inheritance lacks robustness, confirm that the intergenerational avoidance response, but not the elevated <i>daf-7p::gfp</i> expression in F1 progeny, requires <i>sid-1</i> and <i>sid-2</i>, and identify candidate siRNAs and target genes that may mediate this intergenerational response.