Cloning concerns

Scientists working at the Roslin Institute, home of Dolly the sheep, may have discovered why so many cloned animals die before or shortly after birth. The current published success rates are only one or two per cent. Lorraine Young and her colleagues found that manipulating embryos can affect the action of key genes involved in fetal growth and development. In particular, they studied sheep affected by 'large offspring syndrome' (LOS), produced using embryos cultured in the laboratory. The researchers found that they had a less active version of a gene (IGF2R) that normally makes a protein that stops the fetus from growing too large.

Young thinks that cloned animals may suffer from an even greater array of defects than LOS animals, because the embryos undergo greater manipulation, reports New Scientist. 'A lot of us have been trying to nail down what kills clones' said US cloning expert Mark Westhusin. 'This is absolutely a new twist that many people are going to follow up on.' The research was published in the latest issue of the journal Nature Genetics.

Meanwhile, scientists and politicians have reacted with alarm to last week's announcement by two fertility doctors of their plans to begin a human cloning project. 'It would be wholly irresponsible to try and clone a human being, given the present state of the technology' said Dr Harry Griffin, assistant director of the Roslin Institute. The Japanese prime minister Yoshiro Mori has also voiced his opposition to the project, saying that no Japanese scientists would be allowed to participate.