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The role of diatom nanostructures in biasing diffusion to improve uptake in a patchy nutrient environment.

Mitchell JG, Seuront L, Doubell MJ, Losic D, Voelcker NH, Seymour J, Lal R - PLoS ONE (2013)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, Flinders University, Adelaide, South Australia, Australia. jim.mitchell@flinders.edu.au

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.

Principal findings: 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.

Significance: 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.

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The diatoms Coscinodiscus sp. (a–c) and T. eccentrica (d–f) with close ups of their outer surfaces (b and e) and cut away sections of the frustule showing trapping (c) and open (f) morphologies.A schematic shows the effects of trapping (g) and open (h) morphologies, where the net nutrient flux (arrows) after a nutrient pulse passes is inwards (g) or outwards (h). The diatoms are 60 and 30 µm across. The large openings are approximately 1 µm and the small openings are 40 nm. The latter are expanded here for graphical clarity. Additional siliceous membranes with intermediate pore sizes may be present in some forms (c).
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pone-0059548-g004: The diatoms Coscinodiscus sp. (a–c) and T. eccentrica (d–f) with close ups of their outer surfaces (b and e) and cut away sections of the frustule showing trapping (c) and open (f) morphologies.A schematic shows the effects of trapping (g) and open (h) morphologies, where the net nutrient flux (arrows) after a nutrient pulse passes is inwards (g) or outwards (h). The diatoms are 60 and 30 µm across. The large openings are approximately 1 µm and the small openings are 40 nm. The latter are expanded here for graphical clarity. Additional siliceous membranes with intermediate pore sizes may be present in some forms (c).

Mentions: We looked for adaptations in phytoplankton that we could quantitatively link to the heterogeneous nutrient structure. In particular, we examined the morphology of two commonly occurring diatoms. Our approach was to examine the diffusive resistance of diatom surfaces to nutrients. Electron microscopy and atomic force microscopy imaging showed that the frustules above the cell membranes in Thalassiosira eccentrica (Fig. 4a) and Coscinodiscus sp. (Fig. 4b) are an array of chambers with different size openings at the top and bottom.


The role of diatom nanostructures in biasing diffusion to improve uptake in a patchy nutrient environment.

Mitchell JG, Seuront L, Doubell MJ, Losic D, Voelcker NH, Seymour J, Lal R - PLoS ONE (2013)

The diatoms Coscinodiscus sp. (a–c) and T. eccentrica (d–f) with close ups of their outer surfaces (b and e) and cut away sections of the frustule showing trapping (c) and open (f) morphologies.A schematic shows the effects of trapping (g) and open (h) morphologies, where the net nutrient flux (arrows) after a nutrient pulse passes is inwards (g) or outwards (h). The diatoms are 60 and 30 µm across. The large openings are approximately 1 µm and the small openings are 40 nm. The latter are expanded here for graphical clarity. Additional siliceous membranes with intermediate pore sizes may be present in some forms (c).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3646848&req=5

pone-0059548-g004: The diatoms Coscinodiscus sp. (a–c) and T. eccentrica (d–f) with close ups of their outer surfaces (b and e) and cut away sections of the frustule showing trapping (c) and open (f) morphologies.A schematic shows the effects of trapping (g) and open (h) morphologies, where the net nutrient flux (arrows) after a nutrient pulse passes is inwards (g) or outwards (h). The diatoms are 60 and 30 µm across. The large openings are approximately 1 µm and the small openings are 40 nm. The latter are expanded here for graphical clarity. Additional siliceous membranes with intermediate pore sizes may be present in some forms (c).
Mentions: We looked for adaptations in phytoplankton that we could quantitatively link to the heterogeneous nutrient structure. In particular, we examined the morphology of two commonly occurring diatoms. Our approach was to examine the diffusive resistance of diatom surfaces to nutrients. Electron microscopy and atomic force microscopy imaging showed that the frustules above the cell membranes in Thalassiosira eccentrica (Fig. 4a) and Coscinodiscus sp. (Fig. 4b) are an array of chambers with different size openings at the top and bottom.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, Flinders University, Adelaide, South Australia, Australia. jim.mitchell@flinders.edu.au

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.

Principal findings: 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.

Significance: 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.

Show MeSH