RNA-sequencing of planarian cocoons

Many flatworms can alternate between asexual and sexual reproduction. The two reproductive modes are enabled by the presence of pluripotent adult stem cells, by generating any type of tissue in the asexual mode, and producing and maintaining germ cells in the sexual mode. The study focused on the bioactive substances in planarians that can induce the differentiation of pluripotent stem cells into germ cells and other reproductive organs (hereafter called sex-inducing substances). Sex-inducing substances are broadly conserved beyond the species barrier, and are present in composite eggs (cocoons) containing a few fertilized eggs and a large number of yolk cells. In order to identify genes involved in the production of sex-inducing substances, RNA-sequencing was performed using cocoons of two planarian species, Dugesia ryukyuensis and Bdellocephala brunnea (phylum Platyhelminthes, class Turbellaria, order Tricladida).