Gene which binds egg to sperm `discovered`

Here`s some good news for infertile couples worldwide -- scientists claim to have discovered a new gene which could enable male sperm to bind to a female egg, a process essential to fertilisation. A team at Durham University says the gene, which makes protein called PDILT, is a major breakthrough that could help improve the effectiveness and even reduce the cost of in-vitro fertilisation (IVF). In their research on mice, the scientists found that when the gene was "switched off" in male mice, less than three per cent of the females`s eggs were fertilised compared to more than 80 per cent in mice when the gene was left switched on. It is the first time that a gene of this type has been linked to fertility, the `Daily Express` reported. Dr Adam Benham, who led the team, said: "The protein is an essential part of the navigation system of sperm. It helps sperm swim through the oviduct to the egg and without it sperm get stuck. Our results show that navigating the oviduct is an important part of the fertilisation process. "Like any navigation system, you have to programme where it is that you want to go and this protein plays an essential role in getting sperm to the right destination, in good shape, and in good time." Though the research is in its early stages, the scientists are hoping that it will effect human sperm-to-egg binding and offer hope to couples hoping to conceive. The team believes the gene could also assist research into new contraceptive techniques that deactivate the gene and prevent sperm reaching the egg and binding it as well as dramatically improve the effectiveness of IVF. The new findings also show the importance of PDILT in the process of sperm-to-egg binding and in enabling sperm to swim past the uterus, ascend the oviduct and to get through the sticky outer layers of an egg. The team honed in on the role of the protein by switching it off in mice and tracking the ability of sperm to bind to and fertilise eggs in Petri dishes and in mice. They noticed sperm from mice with the gene switched off will not bind to a bare egg but will bind to an egg surrounded by cumulous cells. Dr Benham said: "We now hope to discover how the PDILT protein affects fertility in humans. Mutations in the gene may be responsible for unexplained male fertility problems and further research may aid more effective IVF treatment." Dr Masahito Ikawa from Osaka University, Japan, added: "This protein is essential for sperm to migrate successfully and is required for fertility. The next step is to see how this protein works with other proteins to control the sperm binding and fusion process." The findings have been published in the `Proceedings of the National Academy of Sciences` journal.