职称英语综合类阅读理解英文及译文克隆农场_职称英语阅读理解

职称英语综合类阅读理解英文及译文克隆农场

　　Thats unlikely to put off the poultry industry, however, which wants disease resistant birds that grow faster on less food. Producers would like the same meat quantity but to use reduced inputs to get there, says Mike Fitzgerald of Origen. To meet this demand, Origen aims to create an animal that is effectively a clone, he says. Normal cloning doesnt work in birds because eggs cant be removed and implanted, Instead, the company is trying to bulk-grow embryonic stem cells taken from fertilized eggs as soon as theyre laid. The trick is to culture the cells without them starting to distinguish, so they remain pluripotent, says Fitzgerald.

　　Using a long-established technique, these donor cells will then be injected into the embryo of a freshly laid, fertilized recipient egg, forming a chick that is a chimera. Strictly speaking a chimera isnt a clone, because it contains cells from both donor and recipient. But Fitzgerald says it will be enough if, say, 95 percent of a chickens body develops from donor cells. In the poultry world, it doesnt matter if its not 100 percent, he says.

　　Another challenge for Origen is to scale up production. To do this, it has teamed up with Embrex, which produces machines that can inject vaccines into up to 50,000 eggs an hour. Embrex is now trying to modify the machines to locate the embryo and inject the cells into precisely the right spot without killing it.

　　In future, Origen imagines freezing stem cells from different strains of chicken. If orders come in for a particular strain, millions of eggs could be produced in months or even weeks. At present, maintaining all the varieties the market might call for is too expensive for breeders, and it takes years to bread enough chickens to produce the billions of eggs that farmers need.