Nitroplast



A nitroplast is an organelle found in certain species of algae, particularly in the marine algae Braarudosphaera bigelowii. It plays a crucial role in nitrogen fixation, a process previously thought to be exclusive to bacteria and archaea. The discovery of nitroplasts has significant implications for both cellular biology and agricultural science.

Discovery
In 1998, Jonathan Zehr, an ocean ecologist at the University of California, Santa Cruz, found an unknown DNA sequence that appeared to be for an unknown nitrogen-fixing cyanobacterium in the Pacific Ocean, which they called UCYN-A (unicellular cyanobacterial group A). At the same time, Kyoko Hagino, a paleontologist at Kochi University, was working to culture the host organism, B. bigelowii.

The existence of nitroplasts was first proposed by researchers studying the interaction between B. bigelowii and UCYN-A in 2012. Initially, it was hypothesized that UCYN-A facilitated nitrogen fixation, providing compounds like ammonia to the algae. However, subsequent studies led by Jonathan Zehr reported that UCYN-A were organelles.

Structure and function
Nitroplasts exhibit typical organelle characteristics, meeting two key criteria: they are inherited during cell division and rely on proteins provided by the host cell. Through imaging studies, researchers observed that nitroplasts divide along with the host cell, ensuring their passage to daughter cells.

Implications
The discovery of nitroplasts challenges previous notions about the exclusivity of nitrogen fixation to prokaryotic organisms. Understanding the structure and function of nitroplasts opens up possibilities for genetic engineering in plants. By incorporating genes responsible for nitroplast function, researchers aim to develop crops capable of fixing their own nitrogen, potentially reducing the need for nitrogen-based fertilizers and mitigating environmental damage.