Frontlines
Frontlines
Despite some success, reproductive cloning in mammals is still a tricky feat. University of Pennsylvania School of Veterinary Medicine researchers, by tracking the gene Oct4 in mice, have shown how its routine failure to reprogram after nuclear transplant commonly prevents the successful development of mammalian embryos (M. Boiani et al., "Oct4 distribution and level in mouse clones: consequences for pluripotency," Genes & Development, 6[10]:1209-19, May 15, 2002). Producing a clone requires tha