HR: 17:30h
AN: B52F-07    [PDF]
TI: Production of Thiol Species From An Exponential Growth Diatom Under Copper Exposure
AU: * Tang, D
AF: University of Wisconsin - Madison, 660 North Park Street, Madison, WI 53706 United States
AU: Shafer, M M
AF: University of Wisconsin - Madison, 660 North Park Street, Madison, WI 53706 United States
AU: Karner, D A
AF: University of Wisconsin - Madison, 660 North Park Street, Madison, WI 53706 United States
AU: Armstrong, D E
AF: University of Wisconsin - Madison, 660 North Park Street, Madison, WI 53706 United States
AU: Schauer, J
AF: University of Wisconsin - Madison, 660 North Park Street, Madison, WI 53706 United States
AB: The intracellar induction of phytochelatins is a well documented response of eukaryotic microorganisms to aqueous metal exposure. The extracellular release of thiolic compounds from algal species has been observed; and in some cases, this release can contribute a significant fraction of the uncharacterized metal-complexing ligands. Glutathione (GSH) or cysteine is among the detectable thiols excreted. A quantitative assessment of the excretion of thiols from algae cells into growth media is needed to assess the significance of biogenic-thiols as a source of strong ligands in natural waters and as a "forgotten" route in sulfur biogeochemical cycle. Unbuffered growth media (e.g., without adding complexing ligand such as EDTA) have only rarely been used to study the possible release of metal-complexing ligands from algal species, and the ligand titration techniques used varied considerably. The majority of culture studies have applied metal-buffered media. A direct comparison of released ligands under buffered and unbuffered conditions is lacking, partially due to the inherent difficulties of the titration methods applied. Using HPLC with fluorescence detection of thiol-monobromobimane derivatives, we were able to follow the dynamic change of GSH released in both media types during algal growth: (1) the cell quotas for thiols and pigments varied (mostly decreases) with growth time. Therefore, pigment-normalized cellular thiol concentrations were more or less conservative. (2) GSH was released into both the EDTA-buffered and -unbuffered growth media at similar concentrations. (3) at similar available Cu concentrations, EDTA possibly enhanced, rather than hindered, the release of GSH.
DE: 1050 Marine geochemistry (4835, 4850)
DE: 4807 Chemical speciation and complexation
DE: 4855 Plankton
SC: Biogeosciences [B]
MN: 2003 Fall Meeting