[B-PT03] Biocalcification and the Geochemistry of Proxies -Field ecology, Laboratory culture and Paleo

[BPT03-06] 共焦点顕微鏡による大型有孔虫の細胞質形態と小胞内ｐHの可視化

*大野 良和¹、藤田 和彦²、豊福 高志³、中村 崇¹ (1.琉球大学理工学研究科、2.琉球大学理学部物質地球科学科、3.独立行政法人海洋研究開発機構)

キーワード：大型有孔虫, 共焦点顕微鏡, 生体観察, ｐH, 石灰化

Algal symbiont-bearing large benthic foraminifers are primary and carbonate producers as well as paleoenvironmental indicators in tropical and subtropical reef environments. Despite their importance, their cellular physiology is not well known. In the present study, we have developed methods to observe in vivo images of a living symbiotic porcelaneous large foraminifer, Amphisorus kudakajimensis. The Nikon A1 confocal laser scanning microscope with Calcein-AM was used as a fluorescent indicator for visualizing the morphology and streaming of cytoplasm in living A. kudakajimensis. The observations indicated that the cytoplasmic density decreased and reticulopodia were formed at the aperture in the marginal part of intrashell cytoplasm. We also observed vesicles with elevated pH (pH 9.0) and lowered pH (pH 6.0) in reticulopodia-like cytoplasms using a pH-sensitive probe molecule, 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS). The present study demonstrates the use of confocal microscopy in studying cytoplasmic dynamics and the initial calcification processes such as seawater endocytosis and alkalization of seawater vacuoles.