Molecular Insights into the Niche of Harmful Brown Tides

Louie Wurch, Ph.D., 2011
Sonya Dyhrman, Advisor

Recurrent brown tides caused by the harmful alga Aureococcus anophagefferens have decimated coastal ecosystems and shellfisheries.  Nutrient type and supply are thought to be critical in fueling these blooms.  This thesis examines the metabolic strategies utilized by A. anophagefferens for meeting its nitrogen (N) and phosphorus (P) demand at the cellular level.  Chapter two examines the global transcriptional responses of A. anophagefferens to N and P deficiency.  Results demonstrate that A. anophagefferens can utilize multiple forms of organic N and P when inorganic forms become unavailable.  Chapter three analyzed the global protein changes in response to P deficiency and P re-supply.  Consistent with transcript patterns, A. anophagefferens increases protein abundance for many genes involved in inorganic and organic P metabolism when inorganic P is deficient.  Furthermore, A. anophagefferens can adjust its P requirement by switching from phospholipids to sulfolipids when P is unavailable.  Chapter four examines the expression patterns of target genes under controlled culture experiments.  Results show that a phosphate transporter and xanthine/uracil/vitamin C permease are indicators of P and N deficiency, respectively. Together, these findings provide insight into the niche of this harmful species with respect to N and P.