Julian Ohiro Kimura Thesis Defense (Mansi Srivastava, Advisor)


Wednesday, March 23, 2022, 1:00pm


Hybrid Event. Bio Labs Lecture Hall 1080, 16 Divinity Avenue

Title: Development in the acoel Hofstenia miamia and the embryonic origins of stem cells

Abstract: Many animals across the metazoan tree of life are capable of whole-body regeneration, or the regeneration of entire body axes. Notably, whole body regeneration is often mediated by a population of pluripotent stem cells that are present in the adult body. These adult pluripotent stem cells (aPSCs) also share common transcriptional signatures, expressing members of the Piwi family. Given the widespread occurrence and similar genetic profiles of aPSCs, it is reasonable to hypothesize that aPSCs are a fundamental feature of animal biology. Despite aPSCs being a cell type found across many animals and being a key player in regeneration, the mechanisms for their formation during embryogenesis are poorly understood. Deciphering how aPSCs are made would reveal how pluripotent stem cells are specified and maintained in vivo. However, aPSCs are absent among mammals and other well studied model systems, making it necessary to utilize new laboratory models to ask how aPSCs are made. Here, I leveraged the embryos of the highly regenerative acoel worm Hofstenia miamia, a new research organism, to tackle the question of the embryonic origins of their aPSCs called neoblasts. In Chapter 1, I first characterized how Hofstenia undergoes embryogenesis by generating a staging atlas and accompanying transcriptomic data. In Chapter 2, I analyzed single-cell RNA-seq data of Hofstenia during postembryonic and regenerative timepoints to determine the molecular profile of neoblasts in adult animals. In Chapter 3, I generated a single-cell atlas of developing embryos to identify molecular trajectories that could be involved in the formation of cell types during embryogenesis. In Chapter 4, I generated a complete fate-map of early Hofstenia embryos and identified a cellular source of neoblasts.

Committee: Mansi Srivastava (Advisor), Cassandra Extavour (Chair), Elena Kramer, Amy Wagers (SCRB)