Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fish Embryos Possess a Mechanism for Protection against Chemicals

03.09.2013
UFZ researchers discover function of protein as transporter of toxic chemicals in the zebrafish embryo

Researchers at the Helmholtz Centre for Environmental Research (UFZ), together with colleagues from the Swiss Eawag aquatic research institute, have discovered a protein which transports chemicals out of the embryo of the zebrafish and in this way protects the embryo against toxic substances.


Images of zebrafish (Danio rerio) embryos illustrating the function of the transporter protein Abcb4 acting as effective chemical defense by keeping out chemical compounds from the embryos. When exposed to the red, fluorescent dye rhodamine B little dye accumulates in the cells and tissues of the fish embryos because Abcb4 prevents uptake of the dye as can be seen in the image above. When transporter function is disrupted by a chemical inhibitor considerably more dye accumulates in the embryo tissues – the embryo tissues appear brighter as the image below shows. Source: Stephan Fischer/Eawag

However, certain environmental chemicals render this protective mechanism ineffective, so that the fish embryos become more sensitive to toxic substances. The study, published in the scientific journal "BMC Biology", could prove to be of great importance for the future assessment of chemicals.

Fish possess a number of different mechanisms for protection against harmful substances in an aquatic environment. These include, for example, molecular transport systems, such as the so called ABC (ATP binding cassette) transporters, which prevent the penetration of toxic substances into cells. ABC transporters have been well investigated for mammals. For fish and their embryos, however, little is known about such transporters.

Ecotoxicologists Dr. Till Luckenbach (UFZ) and Dr. Stephan Fischer (Eawag) together with other colleagues have now found that the transport protein Abcb4 actively extrudes chemicals from the embryo of the zebrafish (Danio rerio). "A fish embryo already has effective protective capabilities", says Luckenbach. "The importance of such transport systems is generally underestimated in toxicological and ecotoxicological research - but they play a very important role."

When a substance is bound to zebrafish Abcb4 , this triggers cleavage of the energy transfer substance adenosine triphosphate (ATP). The energy which this sets free is utilised to expel this substance from the cell. Abcb4 can repel a multitude of different chemical compounds, as a result of which the embryo is resistant to a multitude of toxic substances. In humans the protein ABCB1 serves this function. Thus, it came as a surprise that it is Abcb4 that in zebrafish acts as "multidrug" or "multixenobiotic" transporter. The homologous ABCB4 of humans, by contrast, is incapable of transporting toxic chemical compounds. Instead, human ABCB4 has a specific function in liver where it channels certain fatty acids into the bile ducts in order to protect the liver cells against aggressive biliary acids.

In experiments with zebrafish embryos in which the expression of Abcb4 protein was suppressed, Luckenbach and his team found that the embryos were much more sensitive to toxic chemicals and that these substances were enriched to a greater extent in the embryo tissue. "Based on this data we concluded that the zebrafish Abcb4 protects the embryo against the toxic impact of chemicals by keeping them out", says Luckenbach.

In follow-on investigations the researchers measured the activity of the transport system, enabling the identification of the chemicals which Abcb4 transports. However, certain substances block the transport mechanism. This inhibition renders its function ineffective, and other harmful substances can penetrate into the organism. "Compounds which inhibit the transporter throw open the doorway for other toxic substances ", says Stephan Fischer." These are also referred to as chemosensitizers, as they make the organism more sensitive to harmful chemicals. This indirect toxic effect plays an important role, above all in mixtures of substances such as frequently found in our environment."

At the UFZ a wide range of environmentally relevant chemicals are currently being investigated for their impact on the Abcb4 transporter system - separately and in mixtures. Luckenbach: "Many effects of substance mixtures may be explained on the basis of the zebrafish Abcb4 protein activity. Zebrafish embryos are used for the assessment of chemicals and for investigations of environmental impact, so we hope that in future our study will contribute to an awareness of the need to incorporate Abcb4 transport processes in toxicological testing directives." Nicole Silbermann

Publication:
Abcb4 acts as multixenobiotic transporter and active barrier against chemical uptake in zebrafish (Danio rerio) embryos
Stephan Fischer, Nils Klüver, Kathleen Burkhardt-Medicke, Mirko Pietsch, Anne-Marie Schmidt, Peggy Wellner, Kristin Schirmer and Till Luckenbach
BMC Biology 2013, 11:69doi:10.1186/1741-7007-11-69
http://www.biomedcentral.com/1741-7007/11/69
Partial funding was provided for this work by the Deutsche Forschungsgemeinschaft (DFG), the Ministry of Environment, Agriculture and Geology of Saxony and the the German Federal Environmental Foundation (DBU).
Further information:
Dr. Till Luckenbach
Helmholtz Centre for Environmental Research (UFZ)
Telephone: 0341-235-1514
http://www.ufz.de/index.php?de=15560
Dr. Stephan Fischer
Eawag / Aquatic Research Institute of the Swiss Federal Institute of Technology
Telephone: +41 (0)58 765 55 67
http://www.eawag.ch/about/personen/homepages/fischest/index
or
Tilo Arnhold / Susanne Hufe (UFZ Press Office)
Telephone: 0341-235-1635, -1630
http://www.ufz.de/index.php?de=640
At Helmholtz Centre for Environmental Research (UFZ), scientists research the causes and ramifications of far-reaching changes in the environment. They focus on water resources, biological diversity, the consequences of climate change and means of adaptation, environmental and bio-technologies, bio-energy, how chemicals behave in the environment, their repercussions on health, modelling and questions of social sciences. Their leitmotif: our research serves the sustainable use of natural resources and, under the influence of climate change, helps safeguard these foundations of life for posterity. UFZ employs a staff of 1,100 employees at its sites in Leipzig, Halle and Magdeburg. Its funding comes from the Federal Government and the states of Saxony and Saxony Anhalt.

http://www.ufz.de/

The Helmholtz Association contributes to solving major and urgent questions within society, sciences and industry through the provision of academic excellence in six fields of research: energy, the earth and environment, health, key technologies, structure of matter and aviation, aerospace and transport. Employing a staff of 35,000 in 18 research centres and equipped with an annual budget in the region of 3.8 billion euro, the Helmholtz Association is Germany's largest scientific organisation. Its work stands in the tradition of the outstanding natural scientist Hermann von Helmholtz (1821-1894).

http://www.helmholtz.de/

Nicole Silbermann/Tilo Arnhold | UFZ News
Further information:
http://www.ufz.de/index.php?en=31974

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>