OLI Grant: A Novel, Lipid-based Assay for Phosphorus Stress in Marine Phytoplankton
Grant Funded: 2005
The subtropical ocean gyres are the largest biomes on earth and the
plankton that dwell in these environments exert immense influence on
global biogeochemical cycles and climate. The dominant
photosynthesizing (i.e. carbon dioxide consuming) plankton in gyres are
cyanobacteria, small prokaryotic cells that have adapted to growing in
these locations where nutrient concentrations are vanishingly low.
Despite these environmental conditions, cyanobacteria in the gyres are
able to consume massive amounts of carbon dioxide and may be
responsible for as much as half of the global marine productivity.
Recent work has shown that the nutrient phosphate may be of key
importance in determining exactly how much photosynthesis cyanobacteria
are able to sustain in the gyres. To test where and when cyanobacteria
are stressed by phosphorus limitation, we propose to investigate the
molecular structure of intact membrane lipids in cyanobacteria.
Glycolipids, which do not contain phosphorus, are key structural
components of the cell membranes in cyanobacteria, and it has been
suggested that these compounds are synthesized preferentially over
phospholipids when cyanobacteria are stressed by phosphorus limitation.
Understanding the relative proportions of phospholipids and
glycolipids in key populations of picoplankton in gyres will offer a
new molecular-level means by which to determine the reliance of these
populations on dissolved phosphorus. Thus, this new lipid-based assay
will provide a powerful means by which to understand the economy of
phosphorus in the subtropical gyres.
Originally published: February 1, 2005