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Unexpected Links Between Earth Science and Biochemistry

Takeshi Hirata (Professor, Crustal Chemistry Laboratory)

My field of expertise is analytical chemistry, particularly mass spectrometry. While striving to improve analytical sensitivity and precision, I have carried out age determinations on more than 100,000 rocks and minerals. In recent years, demands from geoscientists for analytical services have become increasingly stringent, requiring not only further improvements in measurement accuracy but also an expanded age-dating range (from the oldest to the youngest samples) and accelerated analysis with big-data scalability in mind. Through supporting such analyses, I have been able to glimpse the diverse facets of Earth’s evolutionary history.

Age determination depends critically on the detection of trace elements and isotopes. In the latest analyses, it is necessary to accurately measure extremely rare isotopes occurring at a ratio of one in ten billion atoms. Mass spectrometry technology, which has advanced remarkably to meet such rigorous requirements, has also flourished in another research field—life sciences.

Within living systems, various metal elements exist, each playing important biological roles. Research that seeks to elucidate biological functions through the study of metals in organisms is known as metallomics. In metallomics, it is crucial to determine the chemical forms of trace metals in tissues or cells and to identify their spatial distribution. Against this backdrop, our research group has been developing techniques to simultaneously image (visualize) both metals and biomolecules. A key feature of our approach is that it can obtain imaging information on metals—with high quantitative reliability—together with biomolecular signals. The ultrahigh sensitivity techniques I cultivated in geoscience proved essential for developing this imaging methodology.

In imaging analysis for life sciences, the quantitative accuracy of the target molecules is paramount. Conventional mass imaging methods often employed high-energy probe particles, which resulted in the destruction of biomolecules (bond cleavage). By applying proton/metal adduct reactions—known from MALDI—to a post-ionization approach, we succeeded in reducing molecular fragmentation while improving sensitivity and quantitative performance. The figure shows imaging results of metals and biomolecules obtained from mouse brain tissue. By adapting analytical techniques originally developed for geochronology, we were able to resolve one of the persistent challenges in life-science analysis. This underscores the importance of collaboration with researchers outside one’s own field.

In analytical chemistry, there is no final goal: performance can always be improved further. At the same time, collaborative research provides clear milestones and concrete objectives, while also inspiring new directions for methodological innovation. Working with researchers who pursue specific goals in their own disciplines is an exciting and rewarding experience. For me as an analytical chemist, collaboration is indispensable.

“An analytical chemist can never be the star of the show. But as a supporting actor, one can enjoy a lifelong career.”
These were the words of Professor Tatsuya Sekine, who supervised my undergraduate research. While one purpose of research is to find answers, another essential role of natural science is to raise new questions. The process of discovering solutions through free and creative discussions with researchers from other fields is one of the greatest joys of science. Analytical chemists, by being deeply engaged in this very process, can experience science at its core. In this sense, I believe that modern analytical chemists are no longer just supporting actors, but can also fully enjoy being in the spotlight.

Note 1: Matrix-Assisted Laser Desorption/Ionization
Note 2: Technology for which Dr. Koichi Tanaka was awarded the Nobel Prize in Chemistry
Note 3: A technique that separates sampling and ionization of target molecules into two stages. Technology cultivated through age analysis.

To understand the functions of various metal elements present in living organisms, it is necessary to analyze metal elements and biomolecules simultaneously. We have successfully performed simultaneous imaging analysis of metal elements and biomolecules using a mass spectrometry method developed for dating analysis.