title: Direct and indirect influence of sulfur availability on phytoplankton evolutionary trajectories.
abstract: The sulfate facilitation hypothesis suggests that changes in ocean sulfate concentration influenced the rise to dominance of phytoplankton species of the red lineage. The mechanistic reasons for this phenomenon are not yet understood. We started to address this question by investigating the differences in S utilization by algae of the green and red lineages and in cyanobacteria cultured in the presence of either 5 mmol · L-1(approximately equivalent to Paleozoic ocean concentrations) or 30 mmol · L-1(corresponding to post-Mesozoic/extant concentrations) sulfate. The activities of the main enzymes involved in SO42-assimilation changed in response to changes in growth sulfate concentration. ATP sulfurylase showed different kinetics in the various taxa, with an especially odd behavior for the dinoflagellate. Sulfate availability had a modest effect on cell organic composition. Species-specific differences in the use of some elements were instead obvious in algae grown in the presence of different sulfate concentrations, overall confirming that algae of the red lineage do better at high sulfate than algae of the green lineage. The increase in sulfate concentration may thus have had an impact on phytoplankton radiation both through changes in their enzymatic machinery and through indirect repercussion on elemental usage.
authors.affiliation: Laboratory of Algal and Plant Physiology, Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, via Brecce Bianche, 60131, Ancona, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Prioretti
authors.affiliation: Laboratory of Algal and Plant Physiology, Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, via Brecce Bianche, 60131, Ancona, Italy.|Institute of Microbiology, Academy of Sciences of the Czech Republic, Algatech, Trebon, Czech Republic.|National Research Council, Institute of Marine Science, Venezia, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Giordano
mesh_terms: D005075:Biological Evolution; D000460:Chlorophyta / Q000378:metabolism; D000458:Cyanobacteria / Q000378:metabolism; D017377:Diatoms / Q000378:metabolism; D004141:Dinoflagellida / Q000378:metabolism; D010839:Phytoplankton / Q000378:metabolism*; D013455:Sulfur / Q000378:metabolism*
chemical_list: D013455:Sulfur
keywords: ATP sulfurylase; algae evolution; cell composition; elemental stoichiometry; sulfate assimilation; sulfur metabolism