UC San Diego

The central question underlying all four chapters of this thesis is to develop a deeper understanding of the developmental and evolutionary basis for biomineralization in Mollusca. To address this, a model organism is essential; specifically, a molluscan species that has: (i) identified candidate genes involved in shell development, (ii) expression atlases of shell gene patterns during development, and (iii) established functional gene perturbation techniques for studying shell genes during early development. I use the slipper snail, Crepidula, to meet these requirements. In Chapter 1, I conduct proteomic and transcriptomic analyses on shells and mantle tissue to identify shell matrix proteins within the shell's extracellular matrix. In Chapter 2, I assess the evolutionary age of Crepidula shell matrix proteins and determine the localization of shell matrix genes in shell gland cells during larval shell development. In Chapter 3, I develop techniques for CRISPR/Cas9 gene perturbation in Crepidula, demonstrating the first shell matrix protein gene knockout in a molluscan species. Finally, in Chapter 4, I examine a species outside of gastropods, specifically within Polyplacophora, and develop animal husbandry and larval biology techniques for studying shell plate formation in a local chiton species. Together, the work presented here helps lay the foundation for Crepidula as a capable model for conducting mechanistic studies on shell matrix proteins and their regulators.