TY - JOUR
T1 - In situ electron microscopy characterization of intracellular ion pools in mineral forming microalgae
AU - Kadan, Yuval
AU - Aram, Lior
AU - Shimoni, Eyal
AU - Levin-Zaidman, Smadar
AU - Rosenwasser, Shilo
AU - Gal, Assaf
N1 - Publisher Copyright:
© 2020 Elsevier Inc.
PY - 2020/4/1
Y1 - 2020/4/1
N2 - The formation of coccoliths, intricate calcium carbonate scales that cover the cells of unicellular marine microalgae, is a highly regulated biological process. For decades, scientists have tried to elucidate the cellular, chemical, and structural mechanisms that control the precise mineralogy and shape of the inorganic crystals. Transmission electron microscopy was pivotal in characterizing some of the organelles that orchestrate this process. However, due to the difficulties in preserving soluble inorganic phases during sample preparation, only recently, new intracellular ion-pools were detected using state-of-the-art cryo X-ray and electron microscopy techniques. Here, we combine a completely non-aqueous sample preparation procedure and room temperature electron microscopy, to investigate the presence, cellular location, and composition, of mineral phases inside mineral forming microalga species. This methodology, which fully preserves the forming coccoliths and the recently identified Ca-P-rich bodies, allowed us to identify a new class of ion-rich compartments that have complex internal structure. In addition, we show that when carefully choosing heavy metal stains, elemental analysis of the mineral phases can give accurate chemical signatures of the inorganic phases. Applying this approach to mineral forming microalgae will bridge the gap between the low-preservation power for inorganic phases of conventional chemical-fixation based electron microscopy, and the low-yield of advanced cryo techniques.
AB - The formation of coccoliths, intricate calcium carbonate scales that cover the cells of unicellular marine microalgae, is a highly regulated biological process. For decades, scientists have tried to elucidate the cellular, chemical, and structural mechanisms that control the precise mineralogy and shape of the inorganic crystals. Transmission electron microscopy was pivotal in characterizing some of the organelles that orchestrate this process. However, due to the difficulties in preserving soluble inorganic phases during sample preparation, only recently, new intracellular ion-pools were detected using state-of-the-art cryo X-ray and electron microscopy techniques. Here, we combine a completely non-aqueous sample preparation procedure and room temperature electron microscopy, to investigate the presence, cellular location, and composition, of mineral phases inside mineral forming microalga species. This methodology, which fully preserves the forming coccoliths and the recently identified Ca-P-rich bodies, allowed us to identify a new class of ion-rich compartments that have complex internal structure. In addition, we show that when carefully choosing heavy metal stains, elemental analysis of the mineral phases can give accurate chemical signatures of the inorganic phases. Applying this approach to mineral forming microalgae will bridge the gap between the low-preservation power for inorganic phases of conventional chemical-fixation based electron microscopy, and the low-yield of advanced cryo techniques.
KW - Biomineralization
KW - Coccolith
KW - Crystal growth
KW - Diatom
KW - Freeze-substitution
UR - http://www.scopus.com/inward/record.url?scp=85078801785&partnerID=8YFLogxK
U2 - 10.1016/j.jsb.2020.107465
DO - 10.1016/j.jsb.2020.107465
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C2 - 31981742
AN - SCOPUS:85078801785
SN - 1047-8477
VL - 210
JO - Journal of Structural Biology
JF - Journal of Structural Biology
IS - 1
M1 - 107465
ER -