Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


In times of great famine, microalgae digest themselves


AWI researchers decipher the connection between nutrient availability and algae growth

In a recent study, scientists of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have determined the molecular mechanisms which microalgae apply in order to switch from rapid cell division to growth-arrest during times of acute nutrient deficiency.

Emiliania huxleyi

Photo: C. Hoppe / Alfred-Wegener-Institut

In laboratory experiments, the scientists have been able to observe that calcifying microalgae in a state of nutrient deficiency initially tweak their metabolism to be more economic and efficient before, out of necessity, they even partially digest themselves.

The molecular switches for these basic functions of cells are strikingly similar in all living things. Apparently, it is these switches, which, when malfunctioning in humans, cause cells to lose control of their division activity and potentially become cancer cells. The new findings are being published online this week in the journal Frontiers in Marine Science.

"Like all living things, algae depend on the nutrients phosphorus and nitrogen, which are introduced into coastal areas by rivers, or -in the open ocean- are carried up from depth by eddies. If the surface water is fertilized by such nutrients, a race for the precious elements begins in which the various algae compete for the nutrients.

This race only ends when the nutrients which are necessary for cell division are exhausted and the algae are suddenly facing a famine situation," explains Dr Sebastian Rokitta, AWI biologist and lead author of the current study.

Because the algae apparently react differently to the lack of various nutrients, scientists have long assumed that the single-celled organisms take several different countermeasures to efficiently accommodate for each missing nutrients. However, past studies on this subject have often neglected one important aspect: the molecular machinery of the cells.

Usually, the uptake mechanisms for the lacking nutrients, as well as the biomass and lime production of algae have been studied under starvation conditions. A holistic ‘screening’ of many cellular functions at the same time was previously only possible to a very limited extent. "Only recently, genomic sequence data became available for the most common microalgae in the world, Emiliania huxleyi, so we can finally make effective use of our molecular toolbox," explains AWI microbiologist and co-author Dr Uwe John.

By using so-called microarrays, the scientists have been able to simultaneously observe the activity of more than 10,000 genes under different hunger scenarios. The new results show that the genetic programs which run in different hunger situations are largely the same in terms of arresting the cell division and are only slightly modified, depending on the particularly lacking nutrient, e.g., to switch on specific transporters and storage mechanisms. This strategy is very useful for the algae, since it greatly simplifies the management of the complex cellular apparatus.

What is striking, is the close integration of nutrient availability and cellular energy supply in the algal metabolism. "Apparently, the triggered genetic programs also include molecular sensors that stop the cell division, so to speak, in case of low nutrient levels", says the AWI biologist Dr Björn Rost, who was also involved in the study. This mechanism is known to be disturbed, for example, in human cancer cells, accordingly signalling them to continue cellular division and proliferation. Thus, the study also underlines that the molecular mechanisms that control cell division, and which evolved in the early phase of life about 2 billion years ago are still operative.

The research results also demonstrate that, in the case of ongoing life-threatening nutrient starvation, the microalgae begin to 'digest' their own cellular components, to ensure their survival as long as possible.

They cannot maintain this process for very long, though. All those cells that destroy themselves through this emergency measure then unintentionally make their nutrient-containing components available to other algae as well as to their conspecifics. This previously underestimated process seems to favour the long-term evolution of particularly frugal and self-sustaining individuals and is certainly partly responsible for the robustness and resilience of microalgae in the face of nutritional deficiencies.

In the coming years, Sebastian Rokitta and his colleagues will continue to investigate how different species of algae react when their habitat is changed; which types benefit and which suffer. However, the focus of the AWI scientists will then be on the phytoplankton of the North Atlantic and the Arctic Ocean.

Notes for Editors:
The study has been published online under the following title in the journal Frontiers in Marine Science:
Sebastian D. Rokitta, Peter von Dassow, Björn Rost, Uwe John: P- and N-depletion trigger similar cellular responses to promote senescence in eukaryotic phytoplankton (2016). Frontiers in Marine Science, doi: 10.3389/fmars.2016.00109, Link:

Printable photographs can be found in the online version of this press release at:

Your scientific contacts at the Alfred Wegener Institute are:
• Dr Sebastian Rokitta (Tel: +49 (0)471 4831-2096; e-mail: Sebastian.Rokitta(at)
• Dr Björn Rost (Tel.: +49 (0)471 4831-1809; e-mail: Björn.Rost(at)

Your contact in the Communications and Media Department is Sina Löschke (Tel.: +49 (0)471 4831-2008; E-mail: medien(at)

The Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) conducts research in the Arctic, Antarctic and oceans of the high and mid-latitudes. It coordinates polar research in Germany and provides major infrastructure to the international scientific community, such as the research icebreaker Polarstern and stations in the Arctic and Antarctica. The Alfred Wegener Institute is one of the 18 research centres of the Helmholtz Association, the largest scientific organisation in Germany.

Ralf Röchert | idw - Informationsdienst Wissenschaft

More articles from Life Sciences:

nachricht North and South Cooperation to Combat Tuberculosis
22.03.2018 | Universität Zürich

nachricht Researchers Discover New Anti-Cancer Protein
22.03.2018 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Researchers Discover New Anti-Cancer Protein

An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.

The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

Im Focus: Tiny implants for cells are functional in vivo

For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.

In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

Latest News

Custom sequences for polymers using visible light

22.03.2018 | Materials Sciences

Scientists develop tiny tooth-mounted sensors that can track what you eat

22.03.2018 | Health and Medicine

Mat baits, hooks and destroys pollutants in water

22.03.2018 | Earth Sciences

Science & Research
Overview of more VideoLinks >>>