Coccolithogenesis In Scyphosphaera apsteinii (Prymnesiophyceae)

Area of Science:

• Marine biology
• Biomineralization
• Phytoplankton research

Background:

• Coccolithophores are key marine calcite producers, but their calcification mechanisms are unclear.
• Scyphosphaera apsteinii exhibits polymorphic coccolith shapes (muroliths and lopadoliths).
• The Zygodiscales order, including S. apsteinii, lacks detailed ultrastructural and developmental studies.

Purpose of the Study:

• To analyze the cell ultrastructure, morphology, and coccolithogenesis of Scyphosphaera apsteinii.
• To understand the role of cellular components in coccolith formation.
• To investigate the influence of growth irradiance on coccolith composition.

Main Methods:

• Transmission electron microscopy for cell ultrastructure.
• Light microscopy for coccolith secretion and repositioning.
• Analysis of coccolith morphology and arrangement.

Main Results:

• Observed typical haptophyte features and a calcification pattern similar to Emiliania huxleyi.
• Identified the reticular body's role in fine-scale morphology, particularly central pore formation.
• Highlighted the organic matrix's importance in calcite growth and arrangement.
• Demonstrated light irradiance influences lopadolith to murolith ratio.
• Noted S. apsteinii secretes coccoliths attached via fibrillar material.

Conclusions:

• S. apsteinii exhibits dynamic control over coccolith morphology and secretion, influenced by metabolic, sensory, and cytoskeletal factors.
• The reticular body and organic matrix are crucial for coccolith development.
• Growth irradiance significantly impacts coccosphere composition.
• S. apsteinii serves as a valuable model for studying coccolithophore calcification and responses to ocean acidification.