In a groundbreaking research that may pave the way for a male contraceptive, scientists have identified key molecular events that could play a critical role as sperm and egg fuse to create new life.
"This report expands our fundamental understanding of the molecular architecture at the site of sperm-egg fusion," said John Herr from the University of Virginia Health System in US.
"Understanding at the molecular level exactly how the sperm is able to bind with and enter the egg opens opportunities to identify molecules that can disrupt or block the fertilisation event," said Herr.
When the sperm first arrives at the egg, the sperm contains enzymes to help it penetrate the egg and fuse with its target.
The release of these enzymes is known as the acrosomal reaction. The head of the sperm is completely transformed by this reaction, and tremendous changes begin to take place.
But despite this massive remodelling, something intriguing happens, Herr's new research found: A particular protein from within the sperm stays intact at the site of fusion.
This protein - discovered by Herr's lab 15 years ago - remains in place although many other proteins are lost.
The evidence indicates that the protein, ESP1, is stabilising the area where the sperm-egg fusion is occurring.
That ESP1 is conserved in the region of the sperm head that is thought to initiate fusion with the egg during this transformative time after the acrosome reaction suggests ESP1 is playing a key structural role.
"We suspect ESP1 is one of the key molecules that helps to stabilise the equatorial segment region of the sperm head," Herr said.
"Getting at the molecular components of the fertilisation event has a lot of practical applications - as well as intellectual value - because you want to account for all the major components involved in the essential events of the fertilisation cascade," said Herr.
"You want to know which molecules are located precisely where, and when, as the sperm head becomes remodelled prior to fertilisation," said Herr.
"The fundamental questions are, why does the equatorial segment stay intact after the acrosomal reaction? What molecular interactions contribute to its stability?" researchers said.
By answering those questions, researchers could one day find a way to block the protein's interactions and - possibly - prevent pregnancy.
The research was published in the journal Biology of Reproduction.
