Genuine eureka moments are rare in science, but one occurred a decade ago when research into a curious function of bacteria immunology exploded into a Nobel Prize-winning discovery. The 2012 paper by Jennifer Doudna and Emmanuelle Charpentier is already recognised as a landmark of science.
Researchers had been piecing together information about CRISPR (clustered regularly interspaced short palindromic repeats) since the 1980s. In nature, it’s a molecular defence mechanism that bacteria use to detect and destroy the DNA of an invading virus, like a set of microscopic scissors.
When a bacterium is infected, the ‘scissors’ cut and paste a segment of the virus DNA and insert it into its own genome. This trains the system to recognise that DNA and destroy it.
The major breakthrough came when scientists isolated the specific enzymes and RNA (ribonucleic acid) that made up the genetic scissors. Reproducing it in a lab turned CRISPR into a tool that accelerated the speed of biological research. It was a simple way to edit the genomes of any living thing.
How does CRISPR work?
Biotech firms are racing to develop foods that make us healthier or safer, and researchers are developing nuts, wheat, and other foods that are edited to remove allergens. CRISPR-edited tomatoes are already on sale in Japan.
CRISPR is also being used to develop lab-grown meat, and research shows CRISPR reduces LDL (low-density lipoprotein) cholesterol in monkeys by 70 per cent in two weeks.
How can CRISPR could fight climate change?
Weather-resistant foods
Climate change is already affecting crop yields. GM foods aren’t to everyone’s taste, but scientists are using CRISPR to develop crops resistant to drought, heat and floods.
Better biofuels
Gene-edited biofuels could play a key role in providing clean energy. CRISPR has made it possible to produce double the amount of biodiesel from phototropic algae.
Air-purifying plants
Californian scientists are using CRISPR to develop plants that remove CO2 from the atmosphere, thanks to improved photosynthesis and roots that deposit carbon deeper into the soil.
Carbon-extracting microbes
Jennifer Doudna, one of the joint discoverers of CRISPR, has spoken about the potential for CRISPR-modified soils and microbes to extract more carbon from
the atmosphere.
Hardier coral reefs
US scientists are using CRISPR to study genes in coral that affect heat tolerance. They hope it will help conservation efforts as reefs feel the impact of rising sea temperatures and ocean acidification.
Shrinking methane emissions
Methane released during rice production makes up 2 per cent of global greenhouse emissions. CRISPR is being used to create crops and livestock that release less methane.
Could CRISPR bring extinct creatures back to life?
CRISPR holds the potential to take surviving DNA from an extinct species and compare it with the genome of a related, living one. By editing the genome of the living species in the places where it differs, researchers believe they could bring animals back from the dead – or create a hybrid that shares some DNA.
The most iconic example is the woolly mammoth, which died out around 10,000 years ago, and scientists aren’t certain whether they were hunted to the brink by humans, or struggled to survive in Earth’s rising temperatures. Either way, their fate may not be sealed. A number of preserved specimens have been found buried in ice and scientists have not only extracted mammoth DNA, but they’ve also sequenced the entire genome.
Now, researchers are trying to return mammoths to the Arctic tundra. Start-up Colossal is using CRISPR to genetically modify the genomes of Asian elephants so they have cold-adapted traits of their long-dead cousins, like smaller ears and more body fat. It believes the first calves will be born within five years.
Projects to revive animals that went extinct more recently, like the thylacine and the passenger pigeon, are also underway.
What are the challenges with CRISPR?
CRISPR is sometimes described as ‘easy’. It may not be rocket science, but funnily enough, genome editing is still a complex process and it’s very expensive, especially when it comes to curing diseases.
Researchers are refining CRISPR delivery mechanisms, looking for enzymes that may be more effective than Cas9 and trying to limit what is known as ‘off-target effects’. These occur when the process of editing affects not just the target DNA but potentially other genes within the organism as well.
Perhaps the biggest challenges are not technical, however, but ethical. Gene editing has long carried the stigma of ‘playing God’ and researchers interrogate their own work against some of the questions that are often asked about the technology and its use.
Will it lead to greater health inequality as the rich access exclusive treatments? Should you target germline cells, where any edits made are also passed onto the next generation? And as it becomes more accessible, how do you regulate the technology for human healthcare and not human enhancement?
What are CRISPR babies?
In 2018, twin girls were born in China who became known as the ‘CRISPR babies’ – the world’s first genome-edited children. Biophysicist He Jiankui engineered mutations in human embryos, which were later implanted into a woman. He claimed to have disabled a particular gene to give them protection against HIV.
He was jailed in China and condemned by the scientific community for crossing an ethical line by editing the human germline – the mutations he made would be passed on to the girls’ future children.
The rogue scientist was also criticised for not following the normal safety and ethical procedures and fuelling the idea of ‘designer’ babies – the notion that gene-editing will allow future parents to choose everything, from their children’s eye colour to their intelligence.
Ethicists warn that without careful regulation, genome editing could lead to a two-tier society, split between those who are edited and those who are not.
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