title: The role of diatom nanostructures in biasing diffusion to improve uptake in a patchy nutrient environment.
abstract: BACKGROUND
  Diatoms are important single-celled autotrophs that dominate most lit aquatic environments and are distinguished by surficial frustules with intricate designs of unknown function.
  
  
  RESULTS
  We show that some frustule designs constrain diffusion to positively alter nutrient uptake. In nutrient gradients of 4 to 160 times over <5 cm, the screened-chambered morphology of Coscincodiscus sp. biases the nutrient diffusion towards the cell by at least 3.8 times the diffusion to the seawater. In contrast, the open-chambers of Thalassiosira eccentrica produce at least a 1.3 times diffusion advantage to the membrane over Coscincodiscus sp. when nutrients are homogeneous.
  
  
  CONCLUSIONS
  Diffusion constraint explains the success of particular diatom species at given times and the overall success of diatoms. The results help answer the unresolved question of how adjacent microplankton compete. Furthermore, diffusion constraint by supramembrane nanostructures to alter molecular diffusion suggests that microbes compete via supramembrane topology, a competitive mechanism not considered by the standard smooth-surface equations used for nutrient uptake nor in microbial ecology and cell physiology.
authors.affiliation: School of Biological Sciences, Flinders University, Adelaide, South Australia, Australia. jim.mitchell@flinders.edu.au
authors.forename: James G
authors.initials: JG
authors.lastname: Mitchell
authors.forename: Laurent
authors.initials: L
authors.lastname: Seuront
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Doubell
authors.forename: Dusan
authors.initials: D
authors.lastname: Losic
authors.forename: Nicolas H
authors.initials: NH
authors.lastname: Voelcker
authors.forename: Justin
authors.initials: J
authors.lastname: Seymour
authors.forename: Ratnesh
authors.initials: R
authors.lastname: Lal
mesh_terms: D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D017377:Diatoms / Q000166:cytology* / Q000378:metabolism*; D004058:Diffusion; D004777:Environment; D005110:Extracellular Space / Q000378:metabolism; D049329:Nanostructures; D010839:Phytoplankton / Q000378:metabolism