Could an ingenious new technology save humanity from its greatest act of planetary self-harm? It may sound like something out of a science-fiction script. But as a new gene editing technology called CRISPR-Cas9 takes rapid steps toward clinical testing in humans, some are asking if it can also help the world cope with a warming climate.
The CRISPR technique has revolutionised scientists’ ability to manipulate DNA. Mice with muscular dystrophy have already been healed by the process. A trial in China plans to use it to treat sexually transmitted human papilloma virus (which can in some cases lead to cervical cancer). Designer babies, a cure for cancer and an answer to antibiotic resistance are all possible future outcomes, scientists say. But there is another possible future use – it could bring extinct animals back from the dead.
The acronymn stands for “Clustered Regularly Interspace Short Palindromic Repeats”, which is a description of the defining feature of a system that bacteria use to fight infection. Kind of like the natural world’s version of cut-copy-and-paste, a molecule guides a protein, called Cas9, to the targeted gene sequence in a strand of DNA, then snips the sequence out. By repurposing this system for use in plants, animals and humans, scientists are now able to edit genes faster and more efficiently than ever before.
CRISPR also holds the potential to pass these genetic changes on down through the generations and make them permanent. As this excellent RadioLab podcast episode explains, the technology is capable of performing what it known as a “gene drive”. This is when scientists make sure an altered gene is inherited at a higher rate than through natural reproduction alone.
It can thus be used to create – or wipe out – entire features from a species. Want modified mosquitos that are incapable of carrying malaria to out-breed their natural cousins? Scientists have already demonstrated this is possible in the lab.
So what are the downsides? Imagine a scenario where blue-eyed designer babies are given gene drives, and you can start to see some of the ethical issues involved. Not to mention the risks of accidentally mutating non-target genes, or of manipulated organisms developing evolutionary resistance, or the unforeseen impacts that removing one species’ genetic trait might have on the rest of an ecosystem.
Yet while the risks of deploying CRISPR are very real, so too are the risks posed to the natural world by climate change. The burning of fossil fuels is pushing up global temperatures and bringing about a mass extinction event that will have disastrous consequences for biodiversity – not to mention human food chains.
Many species are already evolving on their own: the skulls of alpine chipmunks have changed shape due to climate pressure, while the genetics of pink salmon are adapting to favour earlier migrations. But not all will be able to successfully adapt. According to the Living Planet Index, the world will lose two-thirds of wild animals by 2020.
Some scientists are starting to think that CRISPR-Cas9 could perhaps help stave off this collapse – just as we rely on traditional engineering to provide a new, clean-energy infrastructures, so we might use bio-engineering to build ecosystems capable of withstanding more volatile weather and warmer seas.
Coral reefs, for instance, could be saved from rising sea temperatures by gene editing, says the molecular biologist Rachel Levin.
Warming oceans are already resulting in a breakdown of the symbiotic union between coral animals and the billions of photosynthetic microbes called Symbiodinium that inhabit them and make their food. When its too warm for the Symbiodinium to photosynthesize, the coral expel them from its system. However, if they don’t return, the coral host will eventually die.
Writing in Frontiers of Microbiology, Levin proposes using CRISPR to prevent this breakdown. Rare strains of Symbiodinium can survive in warmer waters, and the relevant genes could be copied and transplanted into the Symbiodinium strains from temperate regions.
Crops for human consumption could also benefit from the same process. The genes from wild tomatoes that can thrive on shorter daylight hours could be transplanted into commercial varieties, plant scientist Professor Zach Lippman told The Cold Spring Harbour laboratory. This means the latter could then continue to be grown successfully in cooler, northern latitudes.
The similarities with more conventionally genetically modified organisms (GMOS) are striking here – but so are the differences. GMOs introduce entirely foreign DNA sequences from other organisms to create variants that would not be found in nature, whereas CRISPR’s gene-editing is more akin to conventional breeding methods.
“We’re not making hugely mutant things,” Levin told the Smithsonian Magazine, of the gene editing plans for coral. “All we’re trying to do is give them an extra copy of a gene they already have to help them out.”
The technology clearly still has a long way to go before it is effective in tackling the impacts of climate change on any kind of scale. It even missed out on this year’s round of Nobel prize – pipped by research into the mechanisms behind sleep rhythms.
But if evolution’s story is one of relentless adaptability, then CRISPR may just be humanity’s opportunity to give a nature a fighting chance.