RT Journal Article SR Electronic T1 Stem cell differentiation trajectories in Hydra resolved at single-cell resolution JF bioRxiv FD Cold Spring Harbor Laboratory SP 460154 DO 10.1101/460154 A1 Stefan Siebert A1 Jeffrey A. Farrell A1 Jack F. Cazet A1 Yashodara L. Abeykoon A1 Abby S. Primack A1 Christine E. Schnitzler A1 Celina E. Juliano YR 2018 UL http://biorxiv.org/content/early/2018/11/03/460154.abstract AB The adult Hydra polyp continuously renews all of its cells using three separate stem cell populations, but the genetic pathways enabling homeostatic tissue maintenance are not well understood. We used Drop-seq to sequence transcriptomes of 24,985 single Hydra cells and identified the molecular signatures of a broad spectrum of cell states, from stem cells to terminally differentiated cells. We constructed differentiation trajectories for each cell lineage and identified the transcription factors expressed along these trajectories, thus creating a comprehensive molecular map of all developmental lineages in the adult animal. We unexpectedly found that neuron and gland cell differentiation transits through a common progenitor state, suggesting a shared evolutionary history for these secretory cell types. Finally, we have built the first gene expression map of the Hydra nervous system. By producing a comprehensive molecular description of the adult Hydra polyp, we have generated a resource for addressing fundamental questions regarding the evolution of developmental processes and nervous system function.