London: Scientists in Britian have discovered a lock-and-key mechanism between sperm and egg cells that helps to explain why some sperm malfunction, a finding that will spare infertile couples years of fruitless treatment.
The research by the team at the universities of Bradford and Leeds fundamentally changes the understanding of the importance sperm has in the developing embryo.
The discovery that human egg can read the father's genetic key and screen out failures will spare millions of infertile couples from undergoing expensive and fruitless IVF treatments, The Independent newspaper reported on Sunday.
"Our work has quite a lot of relevance for humans and society and one of the main ones is infertility," said Dr Martin Brinkworth, a member of the team that discovered the lock-and-key mechanism.
According to the research, published in the journal Genome Research, the molecule at the heart of the lock-and-key mechanism is a protein called CTCF. "CTCF sets the stage during sperm development," said Dr David Iles, of the University of Leeds. "And open bases can be recognised by CTCF in the egg."
Dr David Miller of the university thinks the secret could be that the genetic keys in the sperm don't quite fit their partners' locks. "Our research offers a plausible explanation for why some sperm malfunction," he was quoted as saying by British daily.
The research could explain why so many couples with no apparent reproductive problems are unable to conceive.
According to Iles, there is a definite pattern to the way DNA is packaged in sperm cells. "It is the same in unrelated fertile men, but it is different in the sperm of infertile men."
If a test could be developed to identify these men, up to a quarter of women who have intrusive fertility checks would be spared the procedures. It could also sharply decrease the failure rate of IVF by filtering out male candidates who have no chance of success, the report in the British newspaper said.
Although the egg and sperm each supply half the DNA for the new baby, the egg provides all the cellular support systems, including enzymes and proteins. Until now, it was thought that sperm simply delivered the father's tightly packed DNA to the egg, leaving control and regulation of the process to the mother's DNA.
But the scientists found that some genes are left exposed in sperm, in an "open conformation", allowing them to play an important role in the development of the embryo. "It contradicts the dogma that the egg does everything," said Dr Brinkworth, a senior lecturer at the University of Bradford.