Transcriptional Response to a Dauer-Inducing Ascaroside Cocktail in Late L1 in C. elegans

Abstract

C. elegans larvae choose between dauer diapause and immediate reproductive development in two phases, the first being a choice between L2 and L2d, and the second between dauer and L3 (Golden and Riddle 1984). We used RNA-seq to study the transcriptomic response of well-fed C. elegans when exposed to a cocktail of diapause-inducing ascarosides (ascr#2, ascr#3, and ascr#8) during the L1 larval stage when they first receive cues from their environment and then adapt via developmental programming (Kaplan et al. 2011). This research was performed in N2 wild-type worms and daf-22(ok693) mutants that lack an enzyme necessary for the biosynthesis of ascaroside pheromones (reviewed by Ludewig and Schroeder 2013). We found that early exposure to ascarosides triggers a pervasive transcriptional response that may drive diapause induction within as little as three hours. In N2, 362 genes were significantly differentially expressed at p = 0.001, while in daf-22, 1,007 genes were significantly differentially expressed at p = 0.001. The daf-22 mutant may have more significantly expressed genes when exposed to ascarosides indicating a stronger response as it has never encountered ascaroside signaling previously, even at low levels.

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