Abstract
Large-scale TSS profiling produces a high-resolution, quantitative picture of transcription initiation and core promoter locations within a genome. However, application of TSS profiling to date has largely been restricted to a small set of prominent model systems. We sought to characterize the cis-regulatory landscape of the water flea Daphnia pulex, an emerging model arthropod that reproduces both asexually (via parthenogenesis) and sexually (via meiosis). We performed CAGE with RNA isolated from D. pulex within three developmental states: sexual females, asexual females, and males. Identified TSSs were utilized to generate a ‘Daphnia Promoter Atlas’-a catalog of active promoters across the surveyed states. We carried out de novo motif discovery using CAGE-defined TSSs and identified eight candidate core promoter motifs; this collection includes canonical promoter elements (e.g. TATA, Initiator) in addition to others lacking obvious orthologs. A comparison of promoter activities found evidence for considerable state-specific differential gene expression between states. Our work represents the first global definition of transcription initiation and promoter architecture in crustaceans. The Daphnia Promoter Atlas presented here provides a valuable resource for comparative study of cis-regulatory regions in arthropods, as well as for investigations into the circuitries that underpin meiosis and parthenogenesis.
