Silicification process in diatom algae using different silicon chemical sources: Colloidal silicic acid interactions...

Area of Science:

• Marine biology
• Biogeochemistry
• Cellular metabolism

Background:

• Diatoms are crucial in the ocean's silica cycle, relying on silicon transport for biogenic silica formation.
• Understanding silicon metabolism in diatoms is key to comprehending marine biogeochemical processes.

Purpose of the Study:

• To investigate the interaction properties and internalization mechanisms of silicic acid from diverse silicon sources into diatom cells.
• To elucidate the roles of silicon transporters (SITs) and silaffins (SILs) in diatom silicon uptake.

Main Methods:

• Utilized spin-probe electron paramagnetic resonance (EPR) spectroscopy to study silicic acid interactions.
• Analyzed transcript levels of silicon transporters (SITs) and silaffins (SILs) in synchronized Thalassiosira pseudonana cultures.
• Grew diatoms in media with amorphous biogenic substrates (diatomaceous earth, sponge spicules) and crystalline sodium metasilicate.

Main Results:

• Amorphous biogenic silicon slowed internalization, likely due to colloidal particle formation.
• Sponge spicules showed weaker interactions compared to other silicon sources.
• Silicon transporter (SIT) roles were minor, except for SIT3, which is linked to silicon transport, especially with sponge spicules.
• SIL3 transcripts were expressed with all sources, while SIL1 transcripts were specific to sponge spicules.

Conclusions:

• Diatom silicic acid transport varies based on the silicon source's physico-chemical properties and cell surface interactions.
• Different silicon sources trigger distinct molecular responses, involving specific silicon transporters and silaffins.
• The study highlights the complexity of silicon uptake mechanisms in diatoms, crucial for silica biogenic cycling.