DNA editing



A gene-editing technique called Crispr-Cas9 is at the heart of a monumental moment in the his tory of biomedical research.
“The first term is an acronym for `clustered regularly interspaced short palindromic repeats,' a description of the genetic basis of the method; Cas9 is the name of a protein that makes it work,“ explains Amy Maxmen in Wired. “Technical details aside, Crispr-Cas9 makes it easy , cheap, and fast to move genes around -any genes, in any living thing, from bacteria to people.“
In even simpler terms, the work being done on this technique lends credence to the basic premise of the Jurassic Park movies -that you can take a bunch of DNA from a limited source and combine it with others to bring a species back from extinction, or create various combinant, monster species, as was done in the latest instalment of the movie franchise. “Using the three-year-old technique, researchers have already reversed mutations that cause blindness, stopped cancer cells from multiplying, and made cells impervious to the virus that causes AIDS. Agronomists have rendered wheat invulnerable to killer fungi like powdery mildew, hinting at engineered staple crops that can feed a population of 9 billion on an ever-warmer planet. Bioengineers have used Crispr to alter the DNA of yeast so that it consumes plant matter and excretes ethanol, promis ing an end to reliance on petrochemicals,“ writes Maxmen, adding that two of the most powerful universities in the US -UC Berkeley and the Broad Institute of MIT and Harvard -are battling for the basic patent. As Maxmen puts it, “Depending on what kind of person you are, Crispr makes you see a gleaming world of the future, a Nobel medallion, or dollar signs.“
`Crispr' could at last allow genetics researchers to realise their wildest dreams -bespoke babies, invasive mutants, bioweapons. At the Harvard School of Public Health, a special set of mosquito larvae of the species Anopheles gambiae are having malaria-resistant gene drives inserted into their genomes using Crispr. Techniques to do this have existed for decades, but the thing with this particular technique is that it's incredibly fast. Compared to other methods like using TALENs and zinc-finger nucleases, this is “like trading in rusty scissors for a computer-controlled laser cutter.“ With less than $100, an ordinary arachnologist can snip the wing gene out of a spider embryo and see what happens when that spider matures. The writer says that academic and pharmaceutical company labs have begun to develop Crisprbased research tools, such as cancerous mice -perfect for testing new chemotherapies. A team at MIT, working with Zhang, used Crispr-Cas9 to create, in just weeks, mice that inevitably get liver cancer. That kind of thing used to take more than a year.
All this makes it terribly easy to alter the rules of the biological universe ­ to create a new species or obliterate an existing one. But such tinkering has unexpected, far-reaching consequences on the ecosystem ­ if new genes that wipe out malaria also make mosquitoes go extinct, what will bats eat? No one knows what the rules are ­ or who will be the first to break them.
Credit:Times of India.


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