Abstract

C. elegans feeds on a variety of bacteria, both pathogenic and non-pathogenic, and under starvation, high population density, and other stresses enters diapause by forming the dauer larvae. Our previous work showed that C. elegans, also forms dauers as a mechanism of transgenerational defense against the pathogens P. aeruginosa PAO1 and S. Typhimurium MST1. We proposed that in the bacteria-worm communication, bacterial dsRNAs trigger an RNAi-dependent process, generating endo-siRNA accumulation in the germ line subsequently transmitted to the progeny to promote diapause formation in C. elegans. To understand which genes (small RNAs and mRNA) accumulate in response to pathogens, we performed a comparative differential expression analysis of the worm transcriptome under pathogenesis and on non-pathogenic bacteria. We found that mir-243 is overexpressed, in response to P. aeruginosa PAO1. In vivo gfp expression confirms the overexpression of the miRNA in worms fed with pathogens compared to non-pathogenic bacteria. Importantly, animals with mutations in mir-243 do not form dauers in response to P. aeruginosa PAO1, strongly suggesting a role for this small RNA in the behavioral response to pathogenesis. To construct the gene networks underlying dauer formation under pathogenesis, we used the miRNA-mRNA interactions predicted by five software simultaneously (INTA, RNA duplex, RNAplex, RNAup and PITA), and overlapped them with an additional layer formed by the transcription factors, known to regulate the miRNAs that appeared differentially expressed in our experiments.