Wildlife researchers have long suspected that they require experience to migrate effectively, that their annual journeys are the result of learning from one another, not of genetic inheritance. A songbird hatched in a laboratory, having seen nothing of the natural world, still attempts to begin migration at the right time of year and in the right cardinal direction.īut large mammals like bighorn sheep and moose are a different story. Some of these animals, they’ve found, have their migration pathways written into their genes. And now scientists are starting to figure out how they know where to go, and when. Wildebeest and zebra chase the rains through the Mara ecosystem every year, monarch butterflies trace a path from Mexico to Canada and back, and tiny songbirds fly nonstop for days at a time. "They're not going to replace mice, but it gives another tool to scientists.Large migrations are some of nature's greatest spectacles. "I think cats will become easier to utilize as a model organism now that you can manipulate the genome," VandeWoude says. With an easier way to modify genes related to vision, researchers may be able to gain an even higher understanding of how this part of the brain works. For example, the visual cortex of a cat's brain is a better model for humans than the visual cortex from mice is. The advance also makes it easier to use cats as model organisms for other biological questions, she says. Researchers can use the same method to test whether other antiviral proteins from humans and monkeys affect the transmission of FIV, says veterinarian Susan VandeWoude of Colorado State University in Fort Collins. Poeschla and colleagues next plan to test whether the cats are resistant to FIV, or, if not, whether they are less likely to develop feline AIDS after infection. When the researchers tried to infect blood cells from the genetically modified kittens with FIV, the virus didn't replicate well. The method's efficiency is only half the story, however. Almost all of the offspring are transgenic, so you're not screening hundreds of animals to find the transgenic ones." As well as a high number of animals per pregnancy, the number of transgenic animals per embryo is also high. (One kitten was stillborn and another died during birth.) The 23% success rate is much higher than the typical 3% seen with somatic cell nuclear transfer, Poeschla says. Ten of the embryos contained the new genes, and five gave rise to kittens, three of which are still alive. Each cat received 30 to 50 eggs.įive cats became pregnant, with 11 embryos between them, the team reports online today in Nature Methods. After allowing the virus to infect the eggs, the team fertilized them with normal cat sperm and injected them into the fallopian tubes of 22 female cats. The latter allowed them to easily visualize which cells contained the new genetic material-cats with the gene glow green (see picture). Because cells are readily infected by lentiviruses, the researchers made a lentivirus containing the TRIMCyp gene as well as a gene that encodes for a fluorescent protein. Poeschla and his colleagues turned to a different method-using a virus to carry genes into an egg cell-that had worked in animals including mice and cows but never been successful in a carnivore. In cats it's been used to create glowing kittens with no other traits, just proof that it can be made to work. The strategy works in only a fraction of cases. The technique, which produced the famous sheep Dolly, involves replacing the nucleus of an egg cell with a nucleus from an adult cell that contains new genes, then implanting the egg into a female. But the only proven way of getting a new gene into a cat, somatic cell nuclear transfer, is tricky. The protein, which cats lack, is thought to recognize the virus's outer shell and target it to be degraded.Įric Poeschla, a molecular virologist at the Mayo Clinic in Rochester, Minnesota, wanted to figure out if giving cats the TRIMCyp gene would make them immune to FIV. Previous studies have suggested that a protein called TRIMCyp is what keeps humans and monkeys from being infected with FIV. The viruses, known as lentiviruses, are different enough that cats can't catch HIV and people can't get FIV, but most of their basic biochemistry is the same. Whereas we can become infected with the human immunodeficiency virus (HIV), cats fall victim to the feline immunodeficiency virus (FIV), which causes nearly identical symptoms. There are two AIDS epidemics in the world: one in humans, the other in cats. Experts say the advance could make the cat a valuable new genetic model-and potentially protect it from an HIV-like virus. Scientists have genetically modified cats by infecting their eggs with a virus containing a foreign gene-the first time this method has worked in a carnivore.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |