Presentation Information
[O10-01]Visualization of the Biological Calcification Environment: From Geochemical Proxy Calibration to pH Imaging★Invited Papers
*Takashi Toyofuku1 (1.Japan Agency for Marine-Earth Science and Technology (JAMSTEC X-star))
Keywords:
Science and Art,biomineralization,Visualization
Mg/Ca ratios and oxygen isotope ratios recorded in calcareous foraminifera are widely used as major proxies for paleoenvironmental reconstruction. While conducting calibration studies of these proxies, I began to think that it is necessary to directly examine the relationship between the values recorded in the shell and the actual microenvironment during calcification. It is essential to understand under what concentration and chemical conditions calcium ions and carbonate species exist at the moment when environmental signals are incorporated.
During calcification, calcium ions and carbonate ions are taken up, and solid calcium carbonate precipitates. At the same time, trace elements and isotopes are incorporated. However, the ion dynamics and carbonate chemistry at the calcification site cannot be directly observed. The shell remains as a result, but the physicochemical conditions during its formation are not visible.
When I was considering the introduction of a microscope at the beginning of my postdoctoral position, I encountered studies visualizing cellular calcium waves using fluorescent indicators. This became a turning point. I thought that it might be possible to apply this approach to capture calcium dynamics during calcification as moving images. Two years later, after starting my position as a researcher, I began live imaging observations.
Later, I was inspired by attempts to visualize pH distribution in sediments using planar techniques. This led me to expand the approach to visualize pH distribution that controls the carbonate system. In seawater, the chemical form of dissolved carbon dioxide strongly depends on pH. Therefore, measuring pH distribution allows us to estimate the spatial distribution of carbonate ions and bicarbonate ions. By accumulating this approach, in 2017 we demonstrated that calcareous foraminifera actively release protons into seawater during calcification. This phenomenon was clearly detected for the first time by imaging.
The research is still ongoing. It is becoming clear that calcification mechanisms are not uniform among organisms. Different species and conditions show different regulatory strategies. At the same time, we are improving the accuracy of pH imaging and advancing analytical methods together with collaborators. These developments are also being applied to dissolution and precipitation processes of inorganic materials, as introduced in today’s session. Visualization is becoming a useful approach not only for biological calcification but also for understanding solution–solid interactions in general.
The process of converting fluorescence intensity to pH values and presenting them as images includes several steps. These steps include calibration, numerical processing, and setting of display scales. In this presentation, I will summarize the research pathway from proxy calibration to environmental visualization. I will explain how we measure and visualize the calcification process, which cannot be directly observed. I will also discuss how the visualized images contribute to the understanding of the phenomenon.
During calcification, calcium ions and carbonate ions are taken up, and solid calcium carbonate precipitates. At the same time, trace elements and isotopes are incorporated. However, the ion dynamics and carbonate chemistry at the calcification site cannot be directly observed. The shell remains as a result, but the physicochemical conditions during its formation are not visible.
When I was considering the introduction of a microscope at the beginning of my postdoctoral position, I encountered studies visualizing cellular calcium waves using fluorescent indicators. This became a turning point. I thought that it might be possible to apply this approach to capture calcium dynamics during calcification as moving images. Two years later, after starting my position as a researcher, I began live imaging observations.
Later, I was inspired by attempts to visualize pH distribution in sediments using planar techniques. This led me to expand the approach to visualize pH distribution that controls the carbonate system. In seawater, the chemical form of dissolved carbon dioxide strongly depends on pH. Therefore, measuring pH distribution allows us to estimate the spatial distribution of carbonate ions and bicarbonate ions. By accumulating this approach, in 2017 we demonstrated that calcareous foraminifera actively release protons into seawater during calcification. This phenomenon was clearly detected for the first time by imaging.
The research is still ongoing. It is becoming clear that calcification mechanisms are not uniform among organisms. Different species and conditions show different regulatory strategies. At the same time, we are improving the accuracy of pH imaging and advancing analytical methods together with collaborators. These developments are also being applied to dissolution and precipitation processes of inorganic materials, as introduced in today’s session. Visualization is becoming a useful approach not only for biological calcification but also for understanding solution–solid interactions in general.
The process of converting fluorescence intensity to pH values and presenting them as images includes several steps. These steps include calibration, numerical processing, and setting of display scales. In this presentation, I will summarize the research pathway from proxy calibration to environmental visualization. I will explain how we measure and visualize the calcification process, which cannot be directly observed. I will also discuss how the visualized images contribute to the understanding of the phenomenon.