[Triumf-seminars] TRIUMF Seminar today at 14:00

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Date/Time: Thu 2004-04-01 at 14:00

Location:  Auditorium          

Speaker:   Maite Maldonado (Dept of Earth and Ocean Sciences, UBC)

Title:     The physiological role of copper in Fe-limited marine phytoplankton

Abstract: On an annual basis, marine phytoplankton (single-celled photosynthetic organisms, or primary producers) reduce 45 Gigatons (1GT = 10^9Kg) of carbon dioxide (CO2) to organic C, accounting for roughly half of the total C fixation on Earth. A fraction of this organic C produced in marine surface waters (~16GT) is exported to the deep ocean as sinking particles. Variations in the magnitude of this so-called "biological C pump" affect the CO2 content of the upper ocean, which in tern regulates atmospheric CO2 levels - and hence climate - on the time scales ranging from 100 to 1000 years. In order to understand the regulation of the global C cycle, it is thus imperative to determine the factors that control oceanic primary productivity. It is now firmly established that phytoplankton growth and thus C sequestration in thirty percent of the world's oceans are limited by dissolved iron availability. Furthermore, speciation studies have demonstrated that the vast majority of this scarce dissolved iron (Fe) is bound to strong organic ligands, resulting in an insufficient supply of inorganic Fe for growth of even the smallest phytoplankton. A pardox thus exists as to how eukaryotic phytoplankton, which internalized inorganic Fe exclusively, are able to inhabit oceanic waters at all, and grow, albeit slowly, with such low concentrations of inorganic Fe. This research project will investigate mechanisms of Fe acquisition by Fe-limited phytoplankton. In particular, we will investigate the role of copper (Cu) in their high-affinity Fe transport system. We will also examine possible replacements of Fe by Cu in various biochemical reactions, which will allow phytoplankton to survive in low Fe waters.

Stimulants available 15 minutes before the talk.

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