[B-PT03] Biomineralization and Geochemistry of Proxies

[BPT03-01] Effect of inhibitors (acetazolamide and bafilomycin) on the calcification process of foraminifera.

*Takashi Toyofuku^1,2, Yukiko Nagai^1,3 (1.Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2.Tokyo University of Marine Science and Technology (TUMSAT), 3.National Museum of Nature and Science,Tokyo)

Keywords:foraminifera, calcification, laboratory culture

Calcareous foraminifera is microfossils that are essential for geochemical paleoenvironmental analysis. Foraminifera is also the fundamental producer of calcium carbonate in the marine environment, contributing to the global carbon-calcium cycle in the ocean. In recent years, the uptake of carbon dioxide by the oceans has been increasing due to the anthropogenic increase in carbon dioxide levels, resulting in the acidification of the oceans. In an environment where ocean acidification is prevalent, the equilibrium of the carbonate system is expected to be unfavorable for calcification. In order to assess the effects of ocean acidification, numerous observations have been made on various calcifying organisms through field and culture experiments. It is expected that the effects of ocean acidification will vary among species. In calcareous foraminifera, ocean acidification can affect the calcification process and the "mineralogy" or "crystallography" of calcium carbonate. The authors are trying to understand the calcification process in foraminifera. We want to emphasize the importance of biological processes. The response of foraminifera to ocean acidification varies by species, crystal structure (e.g., hyaline vs. miliolid), and presence or absence of symbionts. In addition, both the chemical composition of the shell and the calcification process should have a significant physiological impact. Here, as in other organisms, enzymes are responsible for the physiological activities of foraminifera. In particular, it is still poorly understood which enzymes promote calcification, what role they play, and whether their functions are inhibited. In this study, we aim to confirm that the target enzymes are involved in calcification by laboratory experiments with enzyme inhibitors and observation of shell formation. We will present the results of the addition of acetazolamide and bafilomycin as inhibitors of carbonic anhydrase and proton pump, respectively, which have been strongly implicated in shell formation in previous studies.