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theses

Coral biomineralization is important at the organismal, ecosystem, and global scales, yet the biological component has not been well understood. In particular, identities, roles, and environmental susceptibility of the proteins retained in coral skeleton were previously unknown. To address this, my thesis sequenced the first coral skeletal proteome, generated the first application of coral cell cultures to understanding the effects of ocean acidification on coral calcification at the cellular and molecular levels, and made the first use of NanoSIMS to test the co-localization of aspartic acid and newly formed aragonite in corals. To determine the proteins directly involved in the coral biomineralization process, I used LC-MS/MS sequencing and a novel genome to sequence the skeletal proteome of the stony coral, Stylophora pistillata. It contains an assemblage of adhesion and structural proteins as well as two highly acidic proteins that constitute a novel coral SOM protein sub-family. I next used cluster analysis to compare mineralizing genes known from coral skeleton, mollusk shell, and sea urchin spines and tests. The analysis suggests that there are few sequence similarities across all three phyla, supporting the independent iii evolution of biomineralization. However, there are core sets of conserved motifs in all three phyla examined, including acidic proteins that appear to be responsible for the nucleation reaction as well as inhibition; structural and adhesion proteins that determine spatial patterning; and signaling proteins that modify enzymatic activities. With the guidance of the sequenced coral skeletal proteome and the cluster analysis, I chose four proteins to focus on for their expression response to increased CO2, and their potential control on calcification, in cell cultures. The results suggest that compensatory molecular adjustments to deal with ocean acidification are successful only up to a point, beyond which these mechanisms cannot compete with local chemical conditions unfavorable to biomineralization. Finally, I used NanoSIMS and S. pistillata cell cultures to develop a method to co-localize highly acidic proteins and newly formed calcium carbonate. Initial results point to both intra- and extracellular roles for these proteins in transporting Ca to the calcification site and adhering cells to each other, substrate, and new mineral.

ETD_6822

Ph.D.

Includes bibliographical references

by Jeana Louise Drake

doi:10.7282/T341701S

ETD doctoral

The author owns the copyright to this work.