de-extinction
about 4000 year ago, hunting by humans helped to drive woolly mammoths (Mammuthus primigenius)to extinction. CRISPR pioneer George Church at Harvard Medical school in Boston,Massachusetts, has attraction for his ambition for his ambitious plan to undo the damage by using CRISPR to transform endangered Indian elephants into woolly mammoths.The goal,he says,would be to release them into a reserve in Siberia,where they would have space to roam.
The plan should wild - but efforts to make mammals more mammoth-like have been going on for a while.Last year,geneticist Vincent Lynch at the University of Chicago in Illinois showed that cells with the mammoth version of a gene for heat-sensing and hair growth could grow in low temperatures,and mice with similar versions prefer the colder parts of a temperature-regulated cage. Church says that he has edited about 14 such genes in elephant embryos.
But editing,birthing and then raising mammoth-like elephants is a huge undertaking. Church says that it would be unethical to implant gene-adited embryos into endangered elephants as part of an experiment.So his lab is looking into ways to build an artificial womb; so far,on such device has ever been shown to work.
There are some de-extinction projects that could prove less challenging.Ben Novak at the University of California,Santa Cruz,for example,wants to resurrect the passenger pigeon (Ectopistes migratorius),a once-ubiquitous bird that was driven to extinction in the late nineteenth century by overhunting.His group is currently comparing DNA from museum specimens to the of modern pigeons.Using PGC meth-ods similar to Dorans,he plans to edit the modern-pigeon genomes so that the birds more closely resemble their extinct counterparts
Novak says that the technology is not yet advanced enough to modify the hundreds of genes that differ between modern and historic pigeons. still,he says that CRISPR has given him the best chance yet of realizing his lifelong dream of restoring an extinct species."I think the project is 100% impossible withous CRISPR," hr says.