Organised by the National Human Genome Research Institute each year, National DNA Day in the US on 25 April celebrates the discovery of DNA’s double helix in 1953 and the completion of the Human Genome Project in 2003. Here, we explore the history of DNA and its discovery’s unparalleled effect on science, medicine and the way we now understand the human body.
Discovering DNA’s structure
Using the pictures that she had taken, Franklin was able to calculate the dimensions of the strands and found the phosphates were on the outside of the DNA helix.
Rosalind Franklin working in her lab. Image: Wikimedia Commons
Meanwhile, at the University of Cambridge, James Watson and Francis Crick deduced the double-helix structure of DNA, describing it as ‘two helical chains each coiled round the same axis’ following a right-handed helix containing phosphate diester groups joining β-D-deoxyribofuranose residues with 3’,5’ linkages.
The discoveries made by these scientists would propel the study of genetics into the modern science we know today. Crick and Watson were awarded the Nobel Prize for Physiology or Medicine alongside Maurice Wilkins, who worked with Rosalind Franklin, in 1962. You can read their original paper here.
Dolly the sheep
Dolly on display at the National Museum of Scotland, UK.
Dolly is arguably the most famous sheep in the world, having been the first mammal to be cloned from an adult cell. Born in 1996, Dolly was part of a series of experiments at the Roslin Institute in Edinburgh to create GM livestock that could be used in scientific experiments.
She was cloned using a technique called somatic cell nuclear transfer, where a cell nucleus from one adult is transferred into an unfertilised developing egg cell of another that has had its nucleus removed, which is then implanted into a surrogate mother.
The scientific legacy of Dolly the sheep. Video: Al Jazeera English
Dolly lived until 2003 when she was euthanised after contracting a form of lung cancer. Many speculated that Dolly’s early death was related to the cloning experiment but extensive health screening throughout Dolly’s life by the Roslin Institute suggest otherwise.
Her creation has led to further cloning projects and could be used in the future to preserve the populations of endangered or extinct species, and has led to significant developments in stem cell research.
In 2009, Spanish researchers announced the cloning of a Pyrenean ibex, which has been extinct since 2000, and was the first cloning of an extinct animal. Unfortunately, the ibex died shortly after birth but there have been a few successful stories since then.
The Human Genome Project
Beginning in 1990 and finishing in 2003, the Human Genome Project was an international research initiative that aimed to write the entire sequence of nucleotide base pairs that make up the human genome, including the mapping of all its genes that determine our physical and functional attributes.
The publicly funded $3bn project was able to map 99% of the human genome with 99.99% accuracy, which included its 3.2bn Mega-base pairs, 20,000 genes and 23 chromosome pairs, and has led to advancements in bioinformatics, personalised medicine and a deeper understanding of human evolution.
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.