TROUT have been created whose surrogate fathers were salmon. The salmon had been engineered so they had the sperm-producing cells of a trout. Although sex cells have been transferred between species before, this is the first time that live offspring have been produced. The technique could eventually be used to breed endangered or valuable species, such as the blue-fin tuna that is highly prized by Japanese diners.
The pioneer of such cross-species transfers was Ralph Brinster and his team at the University of Pennsylvania in Philadelphia. In 1996, they showed that sperm precursor cells from rats would develop into mature…
