The research team took sperm from representative species of each of the major groups of animals and each time they were able to confirm the presence of the human gene called Boule. When they deleted this gene in mice, they found that the mice were healthy apart from an inability to produce sperm.
The finding came as a great surprise; genes related to sexual reproduction are under strong selective pressure and as a result, usually change rapidly through natural selection. The discovery suggests Boule is so essential for sperm production that it has been maintained throughout evolution. Professor Eugene Xu, the senior author of the paper, originally discovered Boule in 2001 and believes it is likely to be the oldest human sperm-specific gene ever discovered.
Just like the insect wing and bird wing evolved independently from each other, prior to this discovery it was not known whether the same was true for the ability to produce sperm.
'This finding suggests that all animal sperm production likely comes from a common prototype', said Professor Xu. 'This is the first clear evidence that suggests our ability to produce sperm is very ancient, probably originating at the dawn of animal evolution 600 million years ago'.
Discovery of this common gene involved in sperm production could have many practical uses for human health. 'A sperm-specific gene like Boule is an ideal target for a male contraceptive drug', said Professor Xu.
The discovery also offers a better understanding of male infertility and opens up a new research window for the future development of pesticides and medicines against infectious parasites. 'We now have one strong candidate to target for controlling their breeding', Professor Xu said. 'Our work suggests that disrupting the function of Boule in animals most likely will disrupt their breeding and put the threatening parasites or germs under control'.
The work by Professor Xu and his colleagues from Northwestern University will be published on July 15th in PLoS Genetics.