NATURE SPINNING NORMS* : MASTER RESEARCH ESSAY

 

'' Protein Power '' : Aardvark or zebrafish, sperm needs the same key to unlock the egg. The union of egg and sperm is critical for every sexually reproducing animal on Earth.

Exactly how that union occurs has long been a mystery to scientists. A study published in the journal Cell shows that an interlocked bundle of three proteins in the key that lets sperm and eggs bind together.

That bundle is shared by animals as distantly related as fish and mammals.

For nearly all animals, life begins with a sperm cell that makes its way to an egg's cell membrane. Somehow, the two cells recognize each other and bind together.

Then, in a flesh, the sperm head passes into the egg, as if stepping through a door. Now the fused cell is a zygote and ready to grow into a new animal.

In earlier research, scientists found four proteins on mammal sperm that are also present on fish sperm and are needed for fertilization.

In the new study, Andrea Pauli, a molecular and developmental biologist at the Research Institute of Molecular Pathology in Vienna, and Collaborators in several other institutions asked how sperm proteins might team up during fertilization.

The researchers relied on AlphaFold, a technology that uses A.I. to predict the shape of a protein.

They set the four sperm proteins shared by mammals and fish against a library of 1,400  other proteins found on cell surfaces in zebrafish testes, looking for potential partners.

AlphaFold predicted that two of the original shared sperm proteins bind to each other, along with a third protein that was previously unknown, creating a team of three.

Lab experiments confirmed the program's guess : Male zebrafish missing the newly discovered third protein were infertile, as were male mice.

The scientists also found evidence that the three sperm proteins were working as a unit, both in zebrafish and humans.

It's quite likely that the same crucial bundle exists in many, or all, animals with backbones,  Dr. Pauli said.

The World Students Society thanks Elizabeth Preston.