Aquatic Sciences Meeting, Albuquerque 2001

SS16 Iron Bioavailability and Limitation to Primary Production (Disciplinary Connections)

Date: Monday, February 12, 2001, Time: 11:45:00 AM

Location: Mesilla

Sunda, W, G, Beaufort Laboratory, NOAA, Beaufort, NC 28516 , USA, bill.sunda@noaa.gov

Kieber, D, J, SUNY-ESF, Chemistry Department, Syracuse, NY 13210, USA, djkieber@mailbox.syr.edu

Huntsman, S, A, Beaufort Laboratory, NOAA, Beaufort, NC 28516, USA,

INFLUENCE OF IRON ON DMSP DYNAMICS IN MARINE ALGAE

Dimethylsulfoniopropionate (DMSP) represents a dominant sulfur species in many algal cells, but its biological function is poorly known. DMSP and its lysis product, dimethyl sulfide (DMS), are readily oxidized to dimethyl sulfoxide (DMSO) and other products by reactive oxygen species (e.g., singlet oxygen, hydroxyl radicals, and hydrogen peroxide), a reaction that removes these toxic species. The DMSO produced can be further oxidized (e.g., to dimethyl sulfone) which removes additional toxic oxidant species. The DMSP/DMS/DMSO system, thus, may function as a cellular antioxidant system. In support of this hypothesis, we found that Fe-limitation of a coastal diatom (Thalassiosira pseudonana) - which should decrease Fe-containing antioxidant enzymes such as peroxidases - resulted in a 9-fold higher cellular DMSP:carbon ratio (0.7 mmol/mol) and a 13-fold higher DMSO/cell C ratio (330 mmol/mol) than observed under Fe-sufficiency. The DMSO/DMSP ratio was extremely high (380), suggesting that DMSP undergoes rapid direct or indirect (via DMS) oxidation to DMSO within the cell. Our results indicate a direct link between iron limitation and the dynamics of DMSP, DMS, and DMSO within algal cells, which could have an important influence on the production and cycling of these compounds in the ocean.

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Aquatic Sciences Meeting, Albuquerque 2001

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