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Genetically-Modified 'Surrogate Hens' Could Lay Eggs of Rare Chicken Breeds, Scientists Say (theguardian.com)
In an effort to preserve rare varieties of chicken breeds and diversify the chicken gene pool, scientists at the University of Edinburgh's Roslin Institute have come up with a plan to breed genetically-modified chickens designed to act as surrogates that would be capable of laying eggs from any rare breed. Such rare breeds include the Nankin, Scots Dumpy and Sicilian Buttercup. The Guardian reports: The surrogacy technique, which places a new, mind-bending twist on the classic chicken or egg question, involves first genetically engineering hens to be sterile. This is done by deleting a gene, called DDX4, that is required for the development of primordial follicles (the precursors to eggs) meaning that the surrogate hens will never lay eggs that are biologically their own. The next step will be to transplant follicles from rare birds into the surrogate (this is done before the surrogate chick is hatched from its own egg), meaning it would go on to lay eggs belonging to entirely different breeds of chicken. Given that the hens would also need to be artificially inseminated with sperm from the same rare variety, the approach may appear unnecessarily convoluted. Why not just breed the rare birds the normal way? The scientists' ultimate goal is to create a gene bank of chicken breeds preserved for posterity, and since primordial follicles can be frozen efficiently, while eggs cannot, the surrogacy technique serves an essential work-around. Mike McGrew, who is leading the project and is the first author on a paper on the work published this week in the journal Development, predicts that the surrogates will be able to lay eggs from any breed, including chicken's wild predecessor, the red junglefowl, but he is doubtful about whether it will work efficiently across species -- it is not likely that the surrogate hens will be giving birth to eagle chicks, for instance. Richard Broad, a field officer for the Rare Breeds Survival Trust, agreed that rare chickens could be a source of valuable genetic variation, potentially carrying variants that would provide resistance against new forms of avian flu. At present, the team is focused on chicken breeds, but expects the technique to work to preserve rare varieties of ducks, geese and quail.
FTA: A 2015 study suggested that this happens in almost all pregnant women, at least temporarily. The researchers tested tissue samples from the kidneys, livers, spleens, lungs, hearts, and brains of 26 women who tragically died while pregnant or within one month of giving birth. The study found that the women had fetal cells in all of these tissues. The researchers knew that the cells were from the fetus, and not from the mother, because the cells contained a Y chromosome (found only in males) and the women had all been carrying sons. In some cases, fetal cells may stay in a woman's body for years. In a 2012 study, researchers analyzed the brains of 59 women ages 32 to 101, after they had died. They found 63 percent of these women had traces of male DNA from fetal cells in their brains. The oldest woman to have fetal cells in her brain was 94 years old, suggesting that these cells can sometimes stay in the body for a lifetime.
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That's part of it. The chicken you get from a store is almost certainly a Cornish Cross, which reaches market weight in something like 5 weeks for a fryer and 8 weeks for a broiler. Heritage breeds (read: "real" chickens) take 20-22 weeks to reach maturity. The meat is very, very different -- dark meat is *dark*, far more flavorful, and requires more time / different methods to cook since the muscles have actually been used. CC's mostly do two things: eat and shit. They really don't move around a whole lot.
Anyway, CC's don't really forage a whole lot anyway, so even if they're raised in a manner that they can eat grass, bugs, etc. they usually don't -- they plop down in front of a feeder and just gorge. They're *amazing* birds, but their quality of life is horrible. It's impossible to beat them on feed conversion ratio, though, which is why that's pretty much all you see. There are some other breeds making their way into the market that take 3-4 more weeks to reach maturity but they're still very, very much in the minority.