A team led by Patrick Martin of the National Oceanography Centre has shown that a species of planktonic marine alga can rapidly change the chemical composition of its cell membranes in response to changes in nutrient supply. The findings indicate that the process may be important for nutrient cycling and the population dynamics of phytoplankton in the open ocean.
Tiny free-floating algae called phytoplankton exist in vast numbers in the upper ocean. Through the process of photosynthesis, they use the energy of sunlight to produce organic compounds required for growth, which draws large amounts of carbon dioxide down from the atmosphere. However, they also need other nutrients such as phosphorus, which is chronically scarce in many oceanic regions.
"We are interested in the adaptations of phytoplankton living in regions where nutrients are in short supply," explained Patrick Martin.
Under normal growth conditions, the cell membranes of phytoplankton contain phosphorus-based lipids called phospholipids. However, it has been appreciated for some time that phytoplankton can exchange their membrane phospholipids with non-phosphorus lipids when phosphorus is in short supply. This substitution saves the cells some phosphorus, which can then be used for other important growth processes such as making new DNA.
"Until now, it has been unclear how rapidly phytoplankton cells are able to change the phosphorus composition of their membranes, and hence whether this process is important over the life-time of individual cells" said Patrick Martin.
To address the issue, he and his collaborators from Woods Hole Oceanographic Institution (WHOI) in the United States performed growth experiments with a species called Thalassiosira pseudonana, which biologists use as a model species representative of a very important group of phytoplankton called diatoms.
They found that when the diatoms were starved of phosphorus their membrane phospholipids were replaced with lipids lacking phosphorus over a couple of days. Moreover, when the diatoms were re-supplied with phosphorus, they rapidly renewed the phospholipid content of their cell membranes, removing the lipids lacking phosphorus.
"Our research now shows that this substitution, at least in the alga we studied, can take place within 24 hours, and is clearly a physiological response by individual cells to the phosphorus concentration in their environment – as opposed to a longer-term adjustment over successive generations," said Patrick Martin.
The researchers also show that when cells have ample phosphorus, their phospholipids contain a surprisingly large amount of phosphorus. Therefore, if these cells suddenly encounter low phosphorus conditions, they have quite a substantial phosphorus reserve in their lipids, which might be significant for supporting further growth.
"Phosphorus concentrations in the ocean can be locally enhanced by physical features such as eddies in the water, and rapid remodelling of lipid membranes might allow phytoplankton to exploit such conditions," said Patrick Martin.
The researchers are Patrick Martin (NOC), and Benjamin Van Mooy, Abigail Heithoff and Sonya Dyhrman (WHOI). The work was conducted while Patrick Martin visited Woods Hole on an exchange programme last autumn.
This research was funded by the United States' National Science Foundation and by the Graduate School of the NOC in Southampton.
Publication: Martin, P., Van Mooy, B. A. S., Heithoff, A. & Dyhrman, S. T. Phosphorus supply drives rapid turnover of membrane phospholipids in the diatom Thalassiosira pseudonana. ISME J. (published online, 16 December 2010).
Dr Rory Howlett | EurekAlert!
International network connects experimental research in European waters
21.03.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
World Water Day 2017: It doesn’t Always Have to Be Drinking Water – Using Wastewater as a Resource
17.03.2017 | ISOE - Institut für sozial-ökologische Forschung
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
23.03.2017 | Life Sciences
23.03.2017 | Power and Electrical Engineering
23.03.2017 | Earth Sciences