Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


When green algae run out of air

Single cell organisms need haemoglobin to survive in an oxygen-free environment

When green algae "can't breathe", they get rid of excess energy through the production of hydrogen. Biologists at the Ruhr-Universität Bochum have found out how the cells notice the absence of oxygen. For this, they need the messenger molecule nitric oxide and the protein haemoglobin, which is commonly known from red blood cells of humans. With colleagues at the UC Los Angeles, the Bochum team reported in the journal "PNAS".

Haemoglobin – an old protein in a new look

In the human body, haemoglobin transports oxygen from the lungs to the organs and brings carbon dioxide, which is produced there, back to the lungs. "However, scientists have known for years that there is not just the one haemoglobin", says Prof. Thomas Happe from the Work Group Photobiotechnology. Nature has produced a large number of related proteins which fulfil different functions. The green alga Chlamydomonas reinhardtii has what is known as a "truncated" haemoglobin, the function of which was previously unknown. Happe's team has deciphered its role in surviving in an oxygen-free environment.

In an oxygen-free environment, the green alga activates specific genes

When Chlamydomonas has no oxygen available, the algae transfer excess electrons to protons, creating hydrogen (H2). "For this to work, the green alga activates a certain gene programme and creates many new proteins", Happe explains. "But how exactly the cells even notice that oxygen is missing is something we did not know." The research team looked for genes that are particularly active when green algae have to live without oxygen – and found a gene that forms the blueprint for a haemoglobin. In an oxygen-rich environment, however, this gene was completely idle.

A haemoglobin and nitric oxide help green algae to survive

The scientists studied the haemoglobin protein and its genetic blueprint in more detail using molecular biological and biochemical analyses. "One thing became clear very quickly", says Dr. Anja Hemschemeier from the Work Group Photobiotechnology. "Algae in which we switched this gene off could hardly grow without oxygen." From previous studies it is known that in many organisms, haemoglobin detoxifies nitric oxide, because an overdose of this gas poisons the cells. The biologists therefore tested whether green algae which are no longer able to form haemoglobin after genetic manipulation die of nitric oxide poisoning. Their expectations: the green algae should fare better if the gas is removed using a chemical scavenger. "Surprisingly, then the algae were not able to grow at all", says Hemschemeier. The researchers concluded that, under oxygen-free conditions, haemoglobin and nitric oxide are in cahoots.

Nitric oxide signals: "no oxygen!"

Nitric oxide acts in many living organisms as a signalling molecule – apparently also in green algae. Experiments in vitro have shown that the green algal haemoglobin interacts with nitric oxide. When the researchers artificially introduced the gas to the single cell organisms, certain genes became active that are otherwise only "turned on" in the absence of oxygen. "From all this data we can conclude that Chlamydomonas uses nitric oxide to pass on the 'no oxygen!' signal within the cell, and that our haemoglobin is involved in this process", Happe sums up. His team wants to go on exploring the role of this protein in green algae, as the biologists have discovered another eleven haemoglobin genes in the organism. "Now things are really getting going", says the Bochum scientist. "The map of haemoglobin research has many blank spots that we want to fill with content. The fact that a single cell requires twelve haemoglobin proteins indicates that these fulfil finely tuned functions in the cell."

Bibliographic record

A. Hemschemeier, M. Düner, D. Casero, S.S. Merchant, M. Winkler, T. Happe (2013): Hypoxic survival requires a 2-on-2 hemoglobin in a process involving nitric oxide, Proceedings of the National Academy of Sciences, doi: 10.1073/pnas.1302592110

Figures online

Three images related to this press release can be found online at:

Further information

Prof. Dr. Thomas Happe, Work Group Photobiotechnology, Department of Plant Biochemistry, Faculty of Biology and Biotechnology at the Ruhr-Universität, 44780 Bochum, Germany, Tel. +49/234/32-27026, E-mail:

Dr. Anja Hemschemeier, Work Group Photobiotechnology, Department of Plant Biochemistry, Faculty of Biology and Biotechnology at the Ruhr-Universität, 44780 Bochum, Germany, Tel. +49/234/32-24282, E-mail:

Editor: Dr. Julia Weiler

Dr. Thomas Happe | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht ‘Farming’ bacteria to boost growth in the oceans
24.10.2016 | Max-Planck-Institut für marine Mikrobiologie

nachricht Calcium Induces Chronic Lung Infections
24.10.2016 | 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: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Oasis of life in the ice-covered central Arctic

24.10.2016 | Earth Sciences

‘Farming’ bacteria to boost growth in the oceans

24.10.2016 | Life Sciences

Light-driven atomic rotations excite magnetic waves

24.10.2016 | Physics and Astronomy

More VideoLinks >>>