ATAC-seq from Strongylocentrotus purpuratus larvae under different environmental conditions during early development

This project contains ATAC-seq files from larvae raised under four different environmental conditions. Shaping of the epigenomic landscape by local environments during early life stages could initiate adaptive plasticity, allowing developing organisms to optimize their phenotypes for local conditions. Elevated seawater temperature, in addition to being an independent stressor, can alter marine microbial communities, leading to increased bacterial loads and pathogen spread, making it imperative to understand how plasticity in physiological and molecular traits of marine organisms are impacted, especially the immune system. We examined how early developmental exposure to elevated temperature and host-associated microbes influence larval morphology, immune cell development, and the epigenome of the purple sea urchin (Strongylocentrotus purpuratus). Embryos were reared in four conditions: ambient or elevated temperature (14C or 18C) and two levels of microbial content (low richness (sterilized artificial sea water; SASW) or high richness (microbiome-exposed; MBE)). Larvae raised in SASW or at 18C were larger and had more pigment cells (antimicrobial immune cells) at 5 days post fertilization than MBE larvae. Development in MBE led to increased chromatin accessibility, predominantly in promoter regions, whereas 18C altered very few chromatin regions but was associated with more differentially expressed genes. Both developmental temperature and microbial content regulate larval metabolism, transcription/translation, and chromatin organization at the gene expression level, but often in opposing directions. Finally, larvae raised in MBE or 18C exhibited delayed immune system development. Overall, we showed that early developmental environments strongly influence whole-organism and molecular phenotypes, with early exposure to microbes altering the host immune system and epigenome.