Title: Casting a wide net: capturing gene regulatory states that drive morphogenesis in marine embryos
Speaker: Deirdre Lyons, PhD, Duke University
One of the most fascinating questions in biology remains how the diversity of organisms we observe in the ocean came to be. For each generation, an animal first acquires its basic bodyplan through the process of development; thus studying development will explain how animals have different shapes, physiologies, and behaviors, each adapted to their unique environment. In many cases, cell fate specification in animals is well-understood, thanks to the study of gene regulatory networks (GRNs). GRNs describe the steps of cellular differentiation over time, with a focus on regulatory connections between transcription factors and signaling molecules. My research addresses aspects of development that are not well-understood, i.e., how a cell’s GRN state launches events outside of the nucleus, for example complex cellular behaviors like migration, cell shape change, or morphogenesis. I use two distantly related groups of marine animals—sea urchins (echinoderms) and snails (gastropod molluscs)—because they are tractable models for studying and manipulating development, and are representatives of the deuterostome and lophotrochozoan branches of the animal tree, respectively. I will discuss my recent work on the sea urchin endoskeleton, a biomineral that supports the pluteus larva during its time in the plankton. I found that matrix metalloproteinases (MMPs) are necessary for biomineralization and characterized the gene regulatory network that controls their expression. I also developed the slipper snail, Crepidula, as a model for studying morphogenetic processes during gastrulation, the period when the body-plan is established and germ layers (ectoderm, endoderm, mesoderm) are segregated. Using advanced in vivo imaging techniques, I uncovered a novel process of cell intercalation that closes the blastopore during gastrulation. Future work will focus on building and comparing gene regulatory networks for cellular processes in these species (e.g., biomineralization), and manipulating them using powerful techniques, such as CRISPR genome editing. Such experiments will lead to a deeper mechanistic understanding of how diverse animal body-plans are constructed, and uncover fundamental mechanisms of animal development. Ultimately, this work serves as the jumpingoff point for asking a wide range of questions about how cell biological processes are controlled, and have influenced biological diversity, across deep evolutionary time scales.
Deirdre Lyons is an MB faculty candidate.