AS WELL as carrying the paternal genome, sperm carry strands of RNA that could play a key role in embryonic development. The discovery might explain some forms of infertility and help improve techniques like cloning.
鈥淒ad鈥檚 doing a little bit more than just adding his DNA,鈥� says Stephen Krawetz of Wayne State University School of Medicine in Detroit, Michigan. He and his colleagues have already shown that, in addition to its payload of DNA, a sperm contains at least 3000 different types of RNA molecules, the blueprints for making proteins. Now, by fertilising hamster eggs with human sperm, they have proved that at least two different RNAs are released into the egg at the moment of conception (Nature, vol 429, p 154). 鈥淲e think there are some early developmental switches set off by these RNAs,鈥� Krawetz says.
If the team鈥檚 theory is right, it might prove possible to improve IVF or treat some forms of infertility by adding the right RNAs to fertilised eggs. The same technique could even improve the efficiency of cloning.
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