This is only the latest in a litany of exotics to ravage American forests. Sixty-two high-impact insect species and a dozen pathogens have arrived since the 1600′s. Only two were detected before 1860.
The emerald ash borer. Image; Wikimedia Commons
Increased global trade and travel, along with climate change and warmer winters, are all fueling the problem. And the devastation has pushed scientists and foresters to look towards biotechnology for a remedy.
‘Almost every day there appears to be a new forest pest and some of these are quite devastating,’ says tree geneticist Jeanne Romero-Severson at the University of Notre Dame, Indiana, US.
‘Biotech approaches such as transgenic technology and CRISPR gene editing could be valuable tools in saving specific species.’
These biotech solutions look sexier to funders, and policymakers, and that is where the resources go. But in many ways, it is a dead end if you don’t have a foundational breeding programme to feed into,’ warns DiFazio, a plant geneticist at West Virginia University, US.
A technology like CRISPR for gene editing is fast and powerful, but mostly it is used in lab organisms where much is known about their genetics. Without deep knowledge of a tree’s genome, CRISPR will be far less useful.
CRISPR is a gene editing tool that first came to prominence in the 1990′s and is considered one of the most disruptive technologies in modern medicine.
Powell, a plant scientist at the State University of New York (SUNY), US acknowledges that ‘the biggest thing is to the get the public onboard; a lot of people are afraid of genetic engineering.
Surveys suggest that knowledge about genetic engineering technology, as well as about threats to forest health, is fairly low amongst the general public. Given these deficits, ‘public opinion might be vulnerable to changes,’ notes Delborne.
Stem cells with shared genetic information aid in the study of human disease. Image: Kyoto University/Knut WoltjenSingle nucleotide polymorphisms (SNPs) are the most common form of genetic mutation, with more than ten million currently identified, and are often found in hereditary diseases – from Alzheimer’s to diabetes.
Due to the precise nature of SNPs, researchers need to compare genetic differences with isogenic twins – two cells which differ in their makeup by only a single gene.
To do this, scientists in Japan have used induced pluripotent stem (iPS) cells to create a novel gene editing technique that can modify DNA to a single gene.
iPS cells are unique in that they retain the genetic makeup of a donor and can be converted into any cell type. These characteristics mean the cells are perfect for testing new treatments in a laboratory setting.
The team – led by Dr Knut Woltjen and based at the Centre for iPS cell Research and Application at Kyoto University, Japan – use the method to insert an SNP modification along with a fluorescent report gene as a marker for the modified cells.
As adding the reporter gene is another modification to the genome, the researchers created a duplicated DNA sequence that flanks the gene in order to remove it.
These strands hang over the sequence of the reporter gene so that once the latter is removed, the two resulting strands can join together – a method known as microhomology-mediated end joining.
In the Alzheimer’s affected brain, abnormal levels of the beta-amyloid protein clump together to form plaques (seen in brown) that collect between neurons and disrupt cell function. Image:NIH Image Gallery
Unique target sites were also added to remove the gene using the enzyme CRISPR, which cuts DNA. As a result, only the modified SNP is left in the genome of the cell.
One of the isogenic twins receives the mutant SNP and the other receives the normal SNP, allowing for a comparison to be made.
Dr Woltjen calls the new technique Microhology-Assisted eXcision, or MhAX. ‘To make MhAX work, we duplicate DNA sequences which are already present in the genome. We then let the cell resolve this duplication. At the same time, the cells decide which SNPs will remain after repair,’ said Woltjen. ‘One experiment results in the full spectrum of possible SNP genotypes.’
The team have already collaborated with other Japanese universities on the application of their novel method, using the HPRT gene – a mutation that can lead to gout – as the first example of its potential use in therapy.
Their work shows that cells with the HPRT mutant SNP had similar issues with metabolism associated with gout patients, while the isogenic control cells had no problems.
Following on from this success, Woltjen and his team are now applying the technique to different diseases associated with SNPs, including diabetes.
CRISPR/Cas9 is a gene editing tool that is swiftly becoming a revolutionary new technology. It allows researchers to edit the genome of a species by removing, adding or modifying parts of the DNA sequence.
To alter DNA using CRISPR, a pre-designed sequence is added to the DNA using a RNA scaffold (gRNA) that guides the enzyme Cas9 to the section of DNA that scientists want to alter. Cas9 ‘snips’ the selected sequence.
At this point, the cell identifies the DNA as damage and tries to repair it. Using this information, researchers can use repair technology to introduce changes to the genes of the cell, which will lead to a change in a genetic trait, such as the colour of your eyes or the size of a plants leaf.
Cas9 unzips the selected DNA sequence as the latter forms bonds to a new genetic code. Adapted from: McGovern Institute for Brain Research at MIT
Public approval of genetic modification is at an all-time high, with a recent YouGov survey finding only 7% of people in the UK oppose gene editing, although there is still a way to go. Lighter regulation in recent years has allowed smaller companies and academic institutions to undertake research.
The future of farming
One of the industries that has benefited from CRISPR is agriculture. The ongoing GM debate is an example of controversial use of transgenesis, the process of inserting DNA from one species into another, spawning fears of ‘Frankenstein foods’.
Instead of creating mega-crops that out-compete all conventional plants, gene editing provides resistance to harsh environments and infections; particularly significant in the context of global food security.
Although gene-editing has been a staple of new agriculture technology for many years now, it is only recently that CRISPR has seen successful use in human disease research and resulting clinical trials.
Scientists at the Salk Institute, California, successfully removed the MYBPC3 gene, linked to a common form of heart disease, from a human embryo. The correction was made at the earliest stage of human development, meaning that the condition could not be passed to future generations.
CRISPR is also being used to study embryo development. Recently, scientists at the Francis Crick Institute, London, discovered that the gene OCT4 was vital in these early stages, although its purpose is still not fully understood. Researchers involved believe that more research into OCT4 could help us improve success rates of IVF and understand why some women miscarry.
A human embryo at day four, taken by a Scanning Electron Microscope. Image: Yorgos Nikas, Wellcome Images
CRISPR is still in the early stages and we are far from editing embryos that can be implanted for pregnancy. Many more safety tests are required before proceeding with any clinical trials, with the next step perhaps replicating the experiment on other mutations such as BRCA1 and BRCA2, the genes responsible for an increased risk of breast cancer.
Experts are confident, however, that this technique could be applied to thousands of other diseases caused by a single mutation, such as cystic fibrosis and ovarian cancers.
The benefits of gene editing are abundant. For example, we may be able to turn the tables on antibiotic-resistant bacteria or ‘super-bugs’ by engineering bacteriophages - viruses that infect bacteria - to target antibiotic resistance genes, knocking them out and allowing conventional antibiotics to work once again. Elsewhere, CRISPR could be used to modify metabolic pathways within algae or corn to produce sustainable and cost-effective ethanol for the biofuel market.
Is CRISPR ethical?
CRISPR and gene editing will revolutionise many industries, but the fear remains in many that we will slip into a society where ‘designer babies’ become the norm, and individuality will be lost.
Marcy Darnovsky, Executive Director of the Centre for Genetics and Society, said in a statement: ‘We could all too easily find ourselves in a world where some people’s children are considered biologically superior to the rest of us.’
Could CRISPR lead to a new generation of superheros? Image: Cia Gould
Dr Lovell-Badge, from the Francis Crick Institute, disagrees. ‘I personally feel we are duty bound to explore what the technology can do in a safe, reliable manner to help people. If you have a way to help families not have a diseased child, then it would be unethical not to do it,’ he said.
Genetic engineering does not have to have an all-or-nothing approach. There is a middle ground that will benefit everyone with correct regulation and oversight. With its globally renowned research base, the UK government has a great opportunity to encourage genetic experiments and further cement Britain’s place as the genetic research hub of the future.