WE ARE a step closer to being able to eliminate some genetic diseases by modifying sperm before they fertilise eggs.
Researchers have long engineered animals by putting DNA into sperm. But the DNA is not integrated into the genome, so these methods mostly produce “mosaic” animals with a mixture of modified and normal cells.
Now US and Japanese researchers have created fully GM zebrafish in one generation (Proceedings of the National Academy of Sciences, vol 101, p 1263). They did it by growing the precursor cells that turn into sperm in the lab and using retroviruses to insert a new…
