Details of Award
NERC Reference : NE/J01138X/1
How do eukaryotic phytoplankton produce the most abundant organo-sulphur compound in the world's oceans?
Grant Award
- Principal Investigator:
- Professor JD Todd, University of East Anglia, Biological Sciences
- Co-Investigator:
- Professor T Mock, University of East Anglia, Environmental Sciences
- Grant held at:
- University of East Anglia, Biological Sciences
- Science Area:
- Atmospheric
- Earth
- Marine
- Overall Classification:
- Marine
- ENRIs:
- Biodiversity
- Global Change
- Science Topics:
- Protein expression
- Biogeochemical Cycles
- Environmental Microbiology
- Environmental Genomics
- Proteomics
- Abstract:
- There is a molecule, called dimethylsulphoniopropionate (DMSP) which is made in very large amounts - a billion tons per year, worldwide - by myriads of tiny single-celled marine plankton, many seaweeds and a few land plants that live near the seaside. In some of these, most of the sulphur and much of the carbon is in the form of this molecule, but the influence of DMSP is even more wide-ranging than that. Despite its abundance, there is no clear agreement as to what is the function of the DMSP - maybe it buffers the cells from the saltiness of the sea, maybe it acts as a defence compound against attack by predators, maybe it protects against ultraviolet light. - maybe it is a molecular jack of all trades. DMSP is not only interesting in its own right, but it also has a chemical legacy, since it is the parent compound for other molecules that are also very important. When the plant-like organisms that make DMSP release it into the environment, either by leakage, or more dramatically when they are lysed by viruses or microscopic animals, it is used as a tasty food source by the teeming marine bacteria and some fungi in a process of DMSP catabolism. This represents a massive part of the global sulphur cycle, but even that is not all. One of the DMSP breakdown products is a gas, called dimethyl sulphide (DMS), which has important environmental impacts in its own right. Of the 300 million tons of DMS made each year in the oceans and their margins, around 10% escapes into the atmosphere, where it gets oxidised to sulphate and sulphuric acid. These molecules act as "Cloud Condensation Nuclei", which cause clouds to form, just as specks of dust can start crystals growing in crystal gardens. This occurs on such a scale that it is responsible for much of the cloud cover over the seas and oceans and may affect the amount of solar heat and light that arrives on Earth - a form of "Global Dimming". The DMS also acts as a signal for many marine animals - birds, seals and tiny crustaceans - since it is a chemical signature for their plankton food supplies. Also to us, as Homo sapiens, DMS is part of the smell of the seaside, especially when there is a lot of seaweed about. Although there have been some nice preliminary studies in which the general pathways for DMSP synthesis have been described, none of the purified enzymes or corresponding genes have been identified in any DMSP-producing organism. This lack of knowledge has made it hard to work out unambiguously what are the true functions of DMSP. This study focuses on one group of phytoplankton, collectively known as diatoms, which produce large amounts of DMSP. These microscopic plant-like organisms are abundant in the world's oceans - all told, they make up a quarter of Earth's plant life by weight and they produce around the same proportion of the oxygen that we breathe. We have very recently identified four key genes in diatoms that we strongly believe encode enzymes that are involved in DMSP production. We now plan to study the exact functions of these genes and the enzymes that they encode by making mutants that no longer make DMSP and, conversely, by engineering strains that over-produce it. This will allow us, for the first time in any organism, to figure out with certainty what are the functions of this key molecule. We will also discover how the genes are expressed; are they switched on all the time, or do they respond to (for example) various stresses in the environment? Does this differ between different species? Not only will this provide new insights on the role(s) of DMSP in diatoms, but our results should shed light on the mechanisms that are involved in this process in other important marine organisms that make this key molecule. Such studies will only strengthen our ability to assess the effects of future environmental changes on this crucial biosynthetic process.
- NERC Reference:
- NE/J01138X/1
- Grant Stage:
- Completed
- Scheme:
- Standard Grant (FEC)
- Grant Status:
- Closed
- Programme:
- Standard Grant
This grant award has a total value of £397,733
FDAB - Financial Details (Award breakdown by headings)
| DI - Other Costs | Indirect - Indirect Costs | DA - Investigators | DA - Estate Costs | DI - Staff | DI - T&S | DA - Other Directly Allocated |
|---|---|---|---|---|---|---|
| £48,756 | £111,470 | £22,954 | £38,476 | £164,693 | £5,410 | £5,974 |
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