A new study reveals how sperm and egg fuse across species

This microscope image provided by Osaka University and the Research Institute of Molecular Pathology in October 2024 shows the fertilization of a mouse egg marked in red and green. The DNA is marked in blue, shown in the egg at the top and in a sperm at the bottom left. (AP)

NEW YORK, Oct. 19 (AP) — New research by scientists in Austria offers tantalizing clues, showing that fertilization works like a lock and key across the animal kingdom, from fish to people.

“We discovered this mechanism that is really fundamental in all vertebrates as far as we can tell,” said co-author Andrea Pauli of the Research Institute for Molecular Pathology in Vienna.

The team found that three sperm proteins come together to form a kind of key that unlocks the egg, allowing the sperm to attach. Their findings, drawn from studies in zebrafish, mice and human cells, show how this process has persisted over millions of years of evolution. The results were published Thursday in the journal Cell.

Scientists had previously known two proteins, one on the surface of the sperm and one on the membrane of the egg. Working with international collaborators, Pauli’s lab used Google DeepMind’s AlphaFold artificial intelligence tool – whose developers were awarded a Nobel Prize earlier this month – to help them identify a new protein that allows the first molecular connection between sperm and egg. They also showed how it works in living things.

It was previously unknown how the proteins “worked together as a team to allow the sperm and the egg to recognize each other,” Pauli said.

Scientists still don’t know how the sperm actually gets inside the egg after they attach, and they hope to dig deeper into this next.

Ultimately, Pauli said, this work could help other scientists better understand infertility or develop new methods of birth control.

The work provides targets for the development of male contraceptives in particular, said David Greenstein, an expert in genetics and cell biology at the University of Minnesota who was not involved in the study.

The latest study “also underscores the importance of this year’s Nobel Prize in Chemistry,” he said in an email.