A cellular memory of developmental history generates phenotypic diversity in C. elegans.

Early life experiences have a major impact on adult phenotypes [1-3]. However, the mechanisms by which animals retain a cellular memory of early experience are not well understood. Here we show that adult wild-type Caenorhabditis elegans that transiently pass through the stress-resistant dauer larval stage exhibit distinct gene expression profiles and life history traits, as compared to adult animals that bypassed this stage. Using chromatin immunoprecipitation experiments coupled with massively parallel sequencing, we found that genome-wide levels of specific histone tail modifications are markedly altered in postdauer animals. Mutations in subsets of genes implicated in chromatin remodeling abolish, or alter, the observed changes in gene expression and life history traits in postdauer animals. Modifications to the epigenome as a consequence of early experience may contribute in part to a memory of early experience and generate phenotypic variation in an isogenic population.