Inorganic carbon acquisition by eukaryotic algae: four current questions

Area of Science:

• * Marine Biology
• * Photosynthesis Research
• * Cellular Biology

Background:

• * Eukaryotic algae exhibit diverse inorganic carbon acquisition strategies.
• * Inorganic carbon concentrating mechanisms (CCMs) are common but incompletely understood.
• * Diffusive CO(2) entry represents an ancestral or secondarily lost mechanism.

Purpose of the Study:

• * To review current understanding of inorganic carbon acquisition in eukaryotic algae.
• * To highlight areas requiring further investigation in algal CCMs.
• * To explore the polyphyletic nature and diversity of algal CCMs.

Main Methods:

• * Review of existing literature on algal inorganic carbon acquisition.
• * Analysis of CCMs in specific model organisms (e.g., Chlamydomonas reinhardtii, marine diatoms).
• * Examination of cyanelle roles in inorganic carbon assimilation.

Main Results:

• * CCMs in eukaryotic algae have arisen independently multiple times (polyphyletically).
• * The CCM of Chlamydomonas reinhardtii involves complex membrane transport and thylakoid lumen processes.
• * Marine diatoms may employ C(4)-like metabolism in their CCMs, with varying findings.
• * Cyanelles in Paulinella and glaucocystophycean algae have distinct origins and roles.

Conclusions:

• * Eukaryotic algal CCMs are diverse and polyphyletic, distinct from cyanobacterial mechanisms.
• * Further research is needed to fully elucidate CCMs in various algal groups, including intermediate forms and cyanelle functions.
• * Understanding these mechanisms is crucial for comprehending algal adaptation and carbon fixation.