title: Expression of a xanthine permease and phosphate transporter in cultures and field populations of the harmful alga Aureococcus anophagefferens: tracking nutritional deficiency during brown tides.
abstract: Targeted gene expression using quantitative reverse transcription polymerase chain reaction (qRT-PCR) was employed to track patterns in the expression of genes indicative of nitrogen or phosphorus deficiency in the brown tide-forming alga Aureococcus anophagefferens. During culture experiments, a xanthine/uracil/vitamin C permease (XUV) was upregulated ∼20-fold under nitrogen-deficient conditions relative to a nitrogen-replete control and rapidly returned to nitrogen-replete levels after nitrogen-deficient cells were resupplied with nitrate or ammonium. It was not responsive to phosphorus deficiency. Expression of an inorganic phosphate transporter (PTA3) was enriched ∼10-fold under phosphorus-deficient conditions relative to a phosphorus-replete control, and this signal was rapidly lost upon phosphate resupply. PTA3 was not upregulated by nitrogen deficiency. Natural A. anophagefferens populations from a dense brown tide that occurred in Long Island, NY, in 2009 were assayed for XUV and PTA3 expression and compared with nutrient concentrations over the peak of a bloom. Patterns in XUV expression were consistent with nitrogen-replete growth, never reaching the values observed in N-deficient cultures. PTA3 expression was highest prior to peak bloom stages, reaching expression levels within the range of P-deficient cultures. These data highlight the value of molecular-level assessments of nutrient deficiency and suggest that phosphorus deficiency could play a role in the dynamics of destructive A. anophagefferens blooms.
authors.affiliation: MIT-WHOI Joint Program in Oceanography/Applied Ocean Science and Engineering, Cambridge, MA, USA; Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543, USA.
authors.forename: Louie L
authors.initials: LL
authors.lastname: Wurch
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Gobler
authors.forename: Sonya T
authors.initials: ST
authors.lastname: Dyhrman
mesh_terms: D020418:Algal Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D057097:Harmful Algal Bloom; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D000459:Phaeophyceae / Q000235:genetics* / Q000378:metabolism; D028061:Phosphate Transport Proteins / Q000235:genetics* / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism; D058009:Stramenopiles / Q000235:genetics* / Q000378:metabolism; D019820:Xanthine / Q000378:metabolism
chemical_list: D020418:Algal Proteins; D026901:Membrane Transport Proteins; D009566:Nitrates; D028061:Phosphate Transport Proteins; D010710:Phosphates; D019820:Xanthine; D010758:Phosphorus; D009584:Nitrogen