A team of researchers including Molecular Biophysics and Integrated Biomaging (MBIB) senior faculty scientist Carolyn Larabell was awarded the Newcomb Cleveland Prize by the American Association for the Advancement of Science (AAAS) for their paper “Nitrogen-fixing organelle in a marine alga.” The research article, which was featured on the cover of Science and was a runner-up for the 2024 Science Breakthrough of the Year, identified a new organelle within single-celled algae that converts nitrogen gas into ammonia.

The research team discovered that a cyanobacteria had evolved to become part of Braarudosphaera bigelowii, rather than a separate, symbiotic partner. They used genomics and proteomics to prove that this structure, the nitroplast, was indeed an organelle. To get proof that nitroplasts are passed on to subsequent generations, they turned to Larabell and then-postdoctoral researcher, Valentina Loconte, in the National Center for X-ray Tomography at the Advanced Light Source.

Alga in various stages of cell division with organelles highlighted in different colors
Soft X-ray tomography image of B. bigelowii undergoing cell division. The nitrogen-fixing entity now considered an organelle is cyan; the algal nucleus is blue, mitochondria are green, and chloroplasts are lilac. (Credit: Valentina Loconte/Berkeley Lab)
Larabell presenting during the special session. (Credit: Mary Maxon)

Using soft-X-ray tomography, Larabell and Loconte visualized the algae and its internal structures throughout the cell cycle. They were able to show how nitroplasts are duplicated through the cell division process and subsequently inherited by the resulting daughter cells. “My lab has been pioneering the soft x-ray tomography,” said Larabell in an interview with ScienceAdvisor. “We’ve struggled for the past 20 years to demonstrate its utility, its ability to uniquely answer biological questions, and this paper does the best job of demonstrating that.”

Loconte (second from left in the first row) and Larabell (center right in the second row) with their fellow awardees. (Credit: Mary Maxon)

The international team gathered at the AAAS Annual Meeting in Boston to present a special session and receive their award during a ceremony on February 14. Larabell, who is also a professor of anatomy at University of California, San Francisco, and Loconte, currently at Diamond Light Source in the UK, were joined by collaborators from UC Santa Cruz, National Taiwan Ocean University, and Kochi University.

Read the ScienceAdvisor article about the research and efforts of the team that led to the award. Visit AAAS to learn more about the 2025 recipients of the Newcomb Cleveland Prize, all of the awards, and watch the tribute video.