Dr Christian Bock (Laboratory Manager)
Dr Jan Tebben
Anyone who’s ever had a slipped disc or injured their knee and had to go inside the ‘tube’ – get an MRI – is familiar with the NMR machine, which uses powerful magnetic fields to produce resonance in atoms and molecules, making the inside of the human body visible. But medical applications aren’t the only thing the technology can be used for: researchers from the AWI use the magnetic fields to investigate animals’ metabolism, to take a closer look at chemical changes in organisms and the environment, and to shed new light on the structure of individual molecules. To do so, they take advantage of the functional principle used in every NMR machine: they generate powerful, oscillating magnetic fields, which produce resonance in hydrogen atoms. Since these atoms can be found in water and in every organic molecule, the resonance pattern allows conclusions to be drawn concerning organisms’ chemical compositions, and concerning internal changes. The devices used at the AWI’s NMR laboratory produce fields that are 180,000 to 280,000 as powerful as the Earth’s magnetic field.
At their laboratory for NMR (Nuclear Magnetic Resonance), the AWI experts employ three different devices, which use the same measuring principle but offer very different perspectives on marine research topics. There is a very large NMR system, weighing in at more than ten metric tons, for studies on living animals, and two NMR spectrometers used to examine individual substances and molecules from tissues and cells. The lab is operated by two groups: the Integrative Ecophysiology Section headed by Dr Christian Bock , and the Ecological Chemistry Section headed by Dr Jan Tebben. The lab is available to all AWI researchers, as well as peers from the AWI’s partner institutes and universities. “With these three devices, we can pursue a broad range of scientific questions,” says Christian Bock, “for example, how the warming and acidification of waters in the Arctic due to climate change will affect those animals that are perfectly adapted to living in the cold.”
Thanks to its extremely high resolution, the AWI’s NMR system can reveal structures down to one-tenth of a millimetre. Researchers can very precisely track metabolic processes within organisms, and investigate where in their bodies, and in which organs, certain effects manifest. “The ability to observe influences on living marine organisms at this resolution is something no other lab in the world can offer,” says Christian Bock. “Normally, NMR machines with such massive field strengths are only used in experimental medical research.”
The NMR system can even be outfitted with a flow channel: temperature-regulated and with an artificial current, the channel allows the researchers to observe how marine organisms like snails, mussels and even fish react to changes in their environment. Using the results, they can deduce how the concentrations of certain metabolic products, e.g. the lactate level, change. Lactate is produced when muscles no longer receive sufficient oxygen. For top athletes, the lactate level is a way of measuring their fitness. In contrast, for Arctic fish that are subjected to rising temperatures, the lactate is an indicator that they are consuming too much oxygen – and are suffering from temperature-related stress.
While the large NMR machine is used to study the metabolism of living organisms, the researchers use the two NMR spectrometers to analyse substances from the organisms, seawater or ice samples. They can investigate how environmental changes impact the composition of molecules in various organisms. The spectrometers can be used in a broad range of settings, making them a valuable asset for researchers from diverse fields. “For example, we can determine what chemical substances microalgae convert atmospheric carbon into,” says Jan Tebben. “Above all, our goal is to understand which substances are most important in this process, and how their production and breakdown are affected by climate change.” This is important information to better understand the global carbon cycle.
In the context of other research, the experts’ goal is to identify the functions of individual molecules – e.g. of essential substances like vitamins, or of defence mechanisms like toxins. “The chemical analysis of molecules allows us to determine their importance for the communication between marine organisms, for symbiotic relationships and for defense,” Tebben explains.
“With the devices at the NMR lab, we’re also helping find answers to fundamental ecological and ecophysiological questions,” says Christian Bock. “For example, we want to better understand how an oyster can survive when the tide recedes and it’s left high and dry, forcing it to close its shell for hours and its heart to stop beating.” Metabolic analysis using magnetic fields can help solve these riddles. “Both students and experts from various fields can use the infrastructure provided at the NMR lab for their projects, helping them make important contributions to basic research,” Bock says. “The real advantage is that the lab is solely dedicated to marine research.”