Andrew Hanson, a plant biochemist and molecular biologist, describes his research in the June 26 issue of the journal Nature. There, he identifies the four steps by which marine algae make DMSP. Hanson explains how marine algae produce DMSP (dimethylsulfoniopropionate), which is converted into DMS (dimethylsulfide), a sulfur gas that helps clouds form in the atmosphere. For the first time, scientists now understand the precise mechanism by which algae make DMSP. Researchers have been interested in unraveling the mysteries of DMSP for more than 30 years.
"This work furthers our understanding of the biological origin of atmospheric dimethylsulfide, which is a significant factor in the global sulfur cycle and may play an important role in climate regulation," said Porter Ridley, program director in NSF's metabolic biochemistry program.
"We have established the biochemistry of how algae convert the common compound methionine -- which is found in all algae -- into DMSP," Hanson explained. Algae produce DMSP to protect themselves from the negative effects of high salinity and freezing. DMSP is also formed in some higher plants that are tolerant to drought, freeze and salt stress, according to Hanson.
"If we can use genetic engineering to transfer the capacity to make this compound from these simple marine organisms into commercial agricultural crops, we should be able to confer a useful degree of drought, freeze and salt tolerance to these plants," Hanson said. "Citrus, for example, would be a particularly good target because it is quite sensitive to freezing and has no DMSP or any related compounds itself."
"We also now have a clearer picture of how marine algae help control world climate," Hanson said. "Since DMS gas from algae is linked to cloud formation, its role in global heating and cooling could be critical. We don't know how future trends in world climate will affect marine algae, but we do know there is a feedback effect operating."
When the DMS sulfur gas in ocean water enters the atmosphere by sea-air exchange, the gas is oxidized into sulfuric acid. Tiny sulfuric acid particles then help promote the formation of clouds which block and reflect heat energy from the sun back into space, resulting in a cooling effect on the earth.
Hanson is not, however, able to predict whether or not global warming will have an impact on marine algae's ability to make more or less DMS, which would affect cloud formation.
Most of the algae used in Hanson's research were collected along the east coast of Florida in Flagler County.
Editors: Photos are available by calling Thomas Wright in Gainesville at: (352) 392-1773.
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