This discovery showcases a new dimension of endosymbiosis, with UCYN-A functioning as a nitroplast—a nitrogen-fixing organelle that advances the evolutionary narrative of eukaryotic symbiosis.
SciFocus/Dec 26, 2024 — A Revolutionary Leap in Symbiosis Research
Researchers have unveiled a groundbreaking discovery in marine biology: a nitrogen-fixing organelle termed the “nitroplast” in a marine alga. Published in Science, this study by Coale et al. explores how the endosymbiotic cyanobacterium Candidatus Atelocyanobacterium thalassa (UCYN-A) has evolved into a fully integrated organelle, advancing our understanding of endosymbiosis and organelle evolution.
“Move over mitochondria—a new organelle, the nitroplast, represents an evolutionary milestone in nitrogen fixation and eukaryotic symbiosis.”
Key Highlights
- Nitroplast Discovery:
- A nitrogen-fixing cyanobacterium, UCYN-A, functions as a specialized organelle in a marine unicellular alga.
- It performs the crucial process of converting atmospheric nitrogen gas (N₂) into biologically available ammonia.
- Evolution Beyond Endosymbiosis:
- Unlike traditional symbionts, UCYN-A has integrated tightly into the algal cellular structure.
- The nitroplast imports essential proteins encoded by the algal genome, indicating its transition into a true organelle.
- Cell Cycle Synchronization:
- Nitroplast division is synchronized with algal cell division, akin to plastids and mitochondria.
- Soft x-ray tomography revealed coordinated splitting and even distribution during cell division.
- Implications for Evolutionary Biology:
- Highlights an early evolutionary stage of organelle development.
- Suggests new avenues for studying the transition from symbiont to organelle in eukaryotes.
- Potential Applications:
- Insights into nitrogen fixation mechanisms could inform sustainable agriculture and biotechnological innovations.
Reference
Coale et al., “Nitrogen-fixing organelle in a marine alga,” Science, Vol 386, 2024. DOI: 10.1126/science.adk1075.
