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Title: Growth on ATP elicits a P-stress response in the picoeukaryote Micromonas pusilla

The surface waters of oligotrophic oceans have chronically low phosphate (P i) concentrations, which renders dissolved organic phosphorus (DOP) an important nutrient source. In the subtropical North Atlantic, cyanobacteria are often numerically dominant, but picoeukaryotes can dominate autotrophic biomass and productivity making them important contributors to the ocean carbon cycle. Despite their importance, little is known regarding the metabolic response of picoeukaryotes to changes in phosphorus (P) source and availability. To understand the molecular mechanisms that regulate P utilization in oligotrophic environments, we evaluated transcriptomes of the picoeukaryote Micromonas pusilla grown under P i-replete and -deficient conditions, with an additional investigation of growth on DOP in replete conditions. Genes that function in sulfolipid substitution and P i uptake increased in expression with P i-deficiency, suggesting cells were reallocating cellular P and increasing P acquisition capabilities. P i-deficient M. pusilla cells also increased alkaline phosphatase activity and reduced their cellular P content. Cells grown with DOP were able to maintain relatively high growth rates, however the transcriptomic response was more similar to the P i-deficient response than that seen in cells grown under P i-replete conditions. The results demonstrate that not all P sources are the same for growth; while M.more » pusilla, a model picoeukaryote, may grow well on DOP, the metabolic demand is greater than growth on P i. Lastly, these findings provide insight into the cellular strategies which may be used to support growth in a stratified future ocean predicted to favor picoeukaryotes.« less
 [1] ;  [1]
  1. Bigelow Laboratory for Ocean Sciences, East Boothbay, ME (United States)
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Grant/Contract Number:
Accepted Manuscript
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Additional Journal Information:
Journal Volume: 11; Journal Issue: 5; Journal ID: ISSN 1932-6203
Public Library of Science
Research Org:
Bigelow Laboratory for Ocean Sciences, East Boothbay, ME (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES; western north-atlantic; dissolved organic phosphorus; sargasso sea; saccharomyces-cerevisiae; phosphatase-activity; community structure; emiliania-huxleyi; marine systems; flow-cytometry; carbonic-acid
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