Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

In times of great famine, microalgae digest themselves

01.07.2016

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: http://journal.frontiersin.org/article/10.3389/fmars.2016.00109/abstract

Printable photographs can be found in the online version of this press release at: http://www.awi.de/nc/en/about-us/service/press/press-release/in-groesster-hungersnot-verdauen-sich-mikroalgen-selbst.html

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

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

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 World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Microscopic trampoline may help create networks of quantum computers

17.07.2018 | Information Technology

In borophene, boundaries are no barrier

17.07.2018 | Materials Sciences

The role of Sodium for the Enhancement of Solar Cells

17.07.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>