Meeting Abstract
Animals that are capable of “whole-body” regeneration are able to replace any missing cell type. Species that are able to undergo whole-body regeneration often do so using a population of adult stem cells that are effectively pluripotent such as the i-cells of cnidarians and neoblasts of planarians. Studying the embryonic origins of these adult stem cells in regenerative species would be the first step in determining the genetic control of stem cell formation. We are studying this question using the new model system Hofstenia miamia, a highly regenerative acoel species that produces experimentally tractable embryos in the laboratory. Hofstenia possess a population of stem cells, also called neoblasts, that are necessary for regeneration and express homologs of piwi. Here, we report an in-depth characterization of embryonic development in Hofstenia miamia. We generated a bulk RNAseq dataset and a developmental atlas by studying gross morphological changes and cellular movements during Hofstenia embryogenesis. A previously undescribed, coordinated cellular movement occurred at about 43-55 hours post laying where the cells on the surface of the animal pole became internalized (“Dimple” stage). in situ hybridization revealed that differentiated cell types and body axes were detectable after the Dimple stage. Finally, to determine when neoblast-like cells emerge during embryogenesis, we performed single cell RNA-seq across developmental stages. Using computational tools, we aim to identify cell lineages and the genes that are required for neoblast formation. The identification of candidate regulators followed by functional studies will enable us to determine the mechanisms for neoblast specification during embryogenesis.
