Talk Title: Transcriptomic reconstruction of embryonic patterning in a vertebrate model and an emerging invertebrate model
Abstract: A fundamental question in developmental biology is how a single totipotent cell gives rise to diverse cell types to form a complex organism during embryogenesis. We leverage single- cell transcriptomic technologies to analyze cell type specification in developing embryos at comprehensive scales. First, we reconstructed the zebrafish cell type transcriptional trajectories using single-cell RNA sequencing (scRNA-seq) data and self-developed R package, URD. The transcriptional trajectories represented the transcriptional paths from a pluripotent progenitor cell type at zygotic genome activation to over 20 specified cell types at organogenesis stage. The trajectories, combined with scRNA-seq analysis of a Nodal signaling mutant, highlighted the concurrent canalization and plasticity of cell fates under morphogen regulation in zebrafish embryogenesis. We next explore cell type specification in Spiralians, a diverse group of invertebrates that exhibit stereotypical asymmetric embryonic cleavage, through which several cell fates emerge. To investigate whether Spiralian early cell type specification is driven by asymmetric inheritance of cellular contents, I adapted MERFISH, a spatial transcriptomics technique, to visualize the transcripts of over 200 genes at subcellular resolution in whole-mount embryos from the slipper snail, Crepidula. This uncovered large groups of differentially localized mRNAs in embryos prior to zygotic genome activation, both subcellularly and between different cells. This data sets the stage for testing how spatially localized transcripts relate to cell fates, and which factors drive asymmetric transcript inheritance during cell division. While classic vertebrate models such as the zebrafish were used to elucidate how embryo can be patterned by morphogen regulated zygotic gene expression, Spiralian species such as Crepidula make a promising model for studying an alternative, complementary approach to embryonic patterning, namely through asymmetric distribution of cellular contents.
Date: Tuesday, April 23rd, 2024
Note: Virtual attendance option is available upon special request. Email CNCM@uci.edu for all requests.
