Stowers Researchers Reveal Evolutionary Flexibility in Meiosis

Stowers Institute Study Reveals Surprising Meiosis Protein Flexibility Across Animals

Meiosis, the carefully managed cellular division where chromosomes pair up, exchange genetic material, and split, serves as the foundation for every sperm and egg cell. When meiosis goes awry in humans, the consequences can include infertility, miscarriage, and birth defects. A recent investigation conducted at the Stowers Institute for Medical Research and featured in Science Advances (DOI: 10.1126/sciadv.aei0758) demonstrated that the biological machinery driving this mechanism is both more adaptable and more widely shared across the animal kingdom than previously recognized. shared across animals than expected, and more flexible.

The Tech TL;DR:

• New research published in Science Advances shows that proteins guiding meiosis are more flexible across animal evolution than previously understood.
• Investigators studying the sea anemone Nematostella discovered that familiar-looking architectural proteins perform different jobs depending on the organism.
• The transparent nature of Nematostella opens pathways for live cell imaging, offering insights into chromosome behavior that remain difficult to observe in traditional mammalian models.

Investigators were surprised to discover that seemingly familiar components did not always perform identical tasks, highlighting an unforeseen versatility in how meiotic processes evolve. “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.”

From Fruit Fly Rotations to Sea Anemone Microscopy

Stefanie “Steffi” Williams, Ph.D., an alumna of the Stowers Graduate School and current postdoctoral fellow at the European Molecular Biology Laboratory, spearheaded the investigation. 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. As a student in the Stowers Graduate School, Williams initially completed a rotation in the Hawley Lab to investigate meiotic processes in Drosophila fruit flies. Following that, Williams transitioned to the Gibson Lab to begin working with Nematostella, a type of sea anemone related to jellyfish and corals that serves as the primary focus for Gibson’s laboratory.

“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.”

Testing Synaptonemal Complex Proteins in Nematostella

In this latest study, Williams discovered that the sea anemone builds a ladder-shaped framework termed the synaptonemal complex between paired chromosomes, much in the same way human cells 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. Male specimens possessing identical genetic alterations remained fertile, while the absence of syce2 interfered with paired chromosome stabilization exclusively in female subjects. “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.”

Live Imaging Advantages Over Traditional Mammalian Models

Prior to this, functional research examining these proteins across the animal kingdom was largely restricted to roundworms, fruit flies, and mice. Because Nematostella features a clear body and its eight gonads can be monitored directly within living specimens, it provides investigators with an advantage that conventional models frequently lack: the capability to observe meiotic division occurring inside living tissues. Consequently, scientists may soon be able to investigate chromosome dynamics that prove challenging or impossible to study within mammalian systems.

“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.”