UC San Diego
Building glass houses: Investigating the molecular biology of diatom silica cell wall formation
- Author(s): Lerch, Sarah Joanne Lux
- Advisor(s): Palenik, Brian
- et al.
Diatoms are a large group of unicellular, photosynthetic eukaryotes which dominate carbon and silicon (Si) biogeochemical cycling in many marine environments. Diatoms influence Si cycling via their silica cell walls which are formed through the conversion of silicic acid from the seawater into amorphous silica. These cell walls may serve a variety of beneficial roles for diatoms, including providing mechanical protection and filtering light.
Diatom cell walls come in a diverse array of morphologies and are characterized by intricate patterns and structures. These characteristics have inspired research into the molecular mechanisms underlying the formation of these striking features. Multiple proteins have been implicated in cell wall formation, including ones which catalyze silica polymerization and others which indirectly influence cell wall ornamentation and size. Despite this, relatively little is known about pattern and structure formation. Understanding the molecular biology of cell wall formation is of interest to ecologists and engineers alike, these insights can be used to better understand the response of diatoms to environmental change and can be leveraged in the application of diatom cell walls in nanotechnology.
The ultimate goal of this dissertation is to enhance our understanding of the molecular basis of cell wall formation in diatoms. This is achieved through the use of genetic manipulation techniques and bioinformatic analyses in the course of three chapters. These approaches are applied in the identification and characterization of the silicalemma associated protein (SAP) family in the diatom Thalassiosira pseudonana (Chapter 1), the study of two actin associated proteins and their influences on silica cell wall formation in T. pseudonana (Chapter 2) and the identification of known and potential cell wall formation proteins in phylogenetically and morphologically diverse diatom genera (Chapter 3).