Key Highlights
New knowledge for fertility research: Nematostella vectensis carries eight of the ten proteins humans use to pair and align meiotic chromosomes, making it a promising system for understanding the process behind human fertility.
Same parts, different jobs: Sea anemone proteins that closely resemble those in mammals do different jobs and can have different roles in males and females.
A path to live imaging: The findings open the door to observing meiotic cell division in living tissue, something that is very hard to do in mammals.
KANSAS CITY, Mo. – October 23, 2026 – Every egg cell and sperm cell depends on meiosis, a tightly choreographed process in which chromosomes find their partners, exchange genetic material, and then divide. When meiosis goes awry in humans, the consequences can include infertility, miscarriage, and birth defects.
A new study from the Stowers Institute for Medical Research , published in Science Advances , shows that the molecular machinery guiding this process is more widely shared across animals than expected, and more flexible. The surprise was that familiar-looking parts were not always doing the same jobs, revealing an unexpected flexibility in how meiosis works across evolution.
"That was one of the broader insights from the paper," said Stowers Investigator and Graduate School President Matt Gibson, Ph.D. "Proteins and protein complexes may look very much the same, but nevertheless function in different ways."
The project was led by Stefanie "Steffi" Williams, Ph.D. , a Stowers Graduate School alum who is currently a postdoctoral fellow at the European Molecular Biology Laboratory . At the Institute, her work grew from a collaboration between Gibson's lab and the lab of the late R. Scott Hawley, Ph.D. , a former Stowers Investigator and a pioneer in the field of meiosis.
In this latest study, Williams found that the sea anemone assembles a ladder-like structure called the synaptonemal complex between paired chromosomes, much as humans do. This structure contains eight of the ten proteins known to make up the synaptonemal complex in humans. But when Williams tested what some of those proteins actually do, the similarities began to break down.
"Despite their essential function, many of the proteins that coordinate meiosis show signatures of rapid evolution, changing much faster than normal housekeeping genes do," said Williams. "So, I was fascinated to find older research showing that cnidarian genomes encode proteins clearly similar to those in humans, and I had to know whether they truly function in the same way."
When Williams disabled three of these proteins, the results were unexpected. Mutations in two of them, sycp1 and syce2, caused female sterility. Males carrying the same mutations remained fertile, and loss of syce2 disrupted the stabilization of paired chromosomes only in females.
"When I first sat at the microscope and saw that some components are not required to synapse chromosomes, I thought I must have made a mistake because it didn't make any sense," said Williams. "Finding out that the architectural functions of synaptonemal complex proteins must have changed was totally unexpected."
Until now, functional studies of these proteins in animals were largely limited to mice, fruit flies, and roundworms. Because Nematostella is transparent and its eight gonads can be observed directly in live animals, it offers researchers something those traditional models often cannot: the potential to watch meiosis unfold in living tissue. That could make it possible to ask questions about chromosome behavior that are difficult or impossible to address in mammals.
"This work establishes Nematostella as a good experimental system for understanding meiotic processes at a deeper level," said Gibson. "The potential for live imaging could reveal new biology that's difficult to observe in mammals, particularly at the cellular level."
As a member of the Stowers Graduate School , Williams first rotated in the Hawley Lab, studying meiosis in the fruit fly Drosophila. Williams then rotated into the Gibson Lab and began to work with Nematostella, a sea anemone and a relative of corals and jellyfish that is the focus of Gibson's research.
"Scott inspired Steffi's passion for meiosis," said Gibson. "When she began working on sea anemones, she became interested in how it worked in these organisms where it hadn't been explored before. This led to a collaboration between labs, and I felt lucky to benefit all along the way from Scott's immense knowledge and Steffi's excitement about the topic, which ultimately led to this new area of research."
"Scott taught me to follow my passion regardless of what others may think of it, as well as the importance of teaching and good mentorship," said Williams. "To this day, Scott inspires me to become a better scientist and human being."
Additional authors include Jennifer Gardner, Ph.D., and Stephanie H. Nowotarski, Ph.D.
About the Stowers Institute for Medical Research
Founded in 1994 through the generosity of Jim Stowers, founder of American Century Investments, and his wife, Virginia, the Stowers Institute for Medical Research is a nonprofit biomedical research organization with a focus on foundational research. Its mission is to expand our understanding of the secrets of life and improve life's quality through innovative approaches to the causes, treatment, and prevention of diseases. The Institute consists of more than 20 independent research programs. Of the approximately 500 members, over 370 are scientific staff that include principal investigators, fellows, technology center directors, postdoctoral scientists, graduate students, and technical support staff. Learn more about the Institute at www.stowers.org and about its graduate program at www.stowers.org/gradschool.
