Background
The authors write that "understanding the production and the export mechanisms of DMSP [dimethylsulfoniopropionate] and DMS [dimethylsulfide] into seawater is important because of the impact the cellular and extracellular pools of these highly relevant biogeochemical metabolites have on the environment," noting that "once ventilated to the atmosphere, DMS is oxidized to form non-sea-salt sulfate and methanesulphonate aerosols, which can exert a cooling effect on climate, both directly (by scattering solar radiation) and indirectly (by increasing cloud albedo," while indicating that "up to 10% of marine primary production is directed toward the synthesis of DMSP (Kiene, et al., 2000)," which is the precursor of DMS.

What was done
Working with Phaeocystis antarctica -- a polar prymnesiophyte or haptophyte (marine microalga or phytoplankton) -- Orellana et al. measured the concentrations of DMS and DMSP in whole cells and isolated secretory vesicles of the species, as well as in samples of broken cells, because, as they elucidate, "in addition to autolysis (Hill et al., 1998), viral lysis (Malin et al., 1998), and zooplankton grazing (Dacey and Wakeham, 1986; Wolfe and Steinke, 1996), it is believed that DMSP passively diffuses into seawater," while noting that "understanding the regulation of this mechanism is necessary in order to obtain a correct partitioning of the cellular and extracellular DMSP and DMS pools in seawater and allow predictions of global budgets."

What was learned
The four U.S. researchers successfully demonstrated that "DMSP and DMS were stored in the secretory vesicles of Phaeocystis antarctica," where "they were trapped within a polyanionic gel matrix, which prevented an accurate measurement of their concentration in the absence of a chelating agent." And in doing so, they found that "the pool of total DMSP in the presence of Phaeocystis may be underestimated by as much as half."

What it means
The results of this study are very significant, because as Orellana et al. note in the concluding sentence of their paper's abstract, "obtaining accurate budget measurements is the first step toward gaining a better understanding of key issues related to the DMS ocean-air interaction and the effect of phytoplankton DMS production on climate change," about which one can read much, much more in the materials filed in our Subject Index under the general heading of Dimethylsulfide.

References
Dacey, J.W.H. and Wakeham, S.G. 1986. Oceanic dimethylsulfide: production during zooplankton grazing. Science 233: 1314-1316.

Hill, R.W., White, B.A., Cottrell, M.T. and Dacey, J.W.H. 1998. Virus-mediated total release of dimethylsulfoniopropionate from marine phytoplankton: a potential climate process. Aquatic and Microbial Ecology 14: 1-6.

Kiene, R.P., Linn, L.J. and Bruton, J.A. 2000. New and important roles for DMSP in marine microbial communities. Journal of Sea Research 43: 209-224.

Malin, G., Wilson, W.H., Bratbak, G., Liss, P.S. and Mann, N.H. 1998. Elevated production of dimethylsulfide resulting from viral infection of cultures of Phaeocystis pouchetii. Limnology and Oceanography 43: 1389-1393.

Wolfe, G.V. and Steinke, M. 1996. Grazing-activated production of dimethyl sulfide (DMS) by two clones of Emiliania huxleyi. Limnology and Oceanography 41: 1151-1160.