Durchflusszytometrische Verfahren in der Quartärforschung: Verbesserung von Radiokohlenstoffdatierungen und Evaluierung stabiler Isotopen- und aDNA-Analysen auf Basis hochreiner fossiler Pollenproben
Physische Geographie
Zusammenfassung der Projektergebnisse
The initial aim of the project was to extract high-purity fossil pollen concentrates from sedimentary archives by means of commercial flow cytometry for different methodological applications (radiocarbon dating, isotopic and aDNA analyses) relevant for palaeoenvironmental and archaeological research. Experiments with commercial flow cytometry (i.e., fluorescence-activated cell sorting) revealed that commonly available highperformance devices optimised mainly for medical research requirements are capable to sort particles of a maximum size of only 85–100 µm and are thus not suitable for sorting the size spectrum (ca. 10–150 µm) of the most common pollen types. This required to adapt the initial project objectives and to first address the need for a method that allows time-efficient (i.e., high-speed) sorting of the most common pollen types. The project achieved to develop a new device capable to sort samples containing particles of up to 200 µm. As the worldwide first application allowing for high-throughput sorting (at least 5 kilohertz) of large-size particles (>100 µm), the novel on-chip sorter with an activation system based on fluorescence detection presents a breakthrough in flow cytometry and concentration of pollen from sediments. The method successfully purified fossil pollen (maximum size ca. 170 µm) from Late Glacial Maximum and Holocene sediments from different lakes. In addition, radiocarbon dates of highpurity pollen concentrates proved accurate, demonstrating the method’s ability to enhance building chronologies for paleoenvironmental records from sedimentary archives. In contrast to commercial sorting systems, the newly developed device is technically more flexible and allows additional implementation of innovative and powerful detection methods, such as highspeed fluorescence or Raman imaging, which facilitates to sort not only whole pollen spectra but also specific pollen types needed to explore the potentials of pollen-based isotope and aDNA analyses in a time- and cost-efficient manner. In addition, it opens up new opportunities in the fields if palaeoenvironmental and archaeological research by extracting other micropalaeontological remains (such as diatoms or phytoliths) from sediments, which is difficult on fluorescence-based methods alone. Another advantage over commercial particle sorters is that the protocol needed for building the new device is published, which makes it easier available for application use or research towards further development.
Projektbezogene Publikationen (Auswahl)
-
2021. Breakthrough in purification of fossil pollen for dating of sediments by a new large-particle on-chip sorter. Science Advances 7, eabe7327
Kasai, Y., Leipe, C., Saito, M., Kitagawa, H., Lauterbach, S., Brauer, A., Tarasov, P.E., Goslar, T., Arai, F., Sakuma, S.
