DNA: the double helix that changed the world

Sixty years ago, a research paper brought an obscure scientific world into the public domain and transformed science, medicine and ethics

Thu, Apr 25, 2013, 06:00

On this day 60 years ago a scientific-research paper was published that would change the world. James Watson and Francis Crick revealed the chemical structure of DNA, the molecule that contains the genetic blueprint and drives inheritance.

For many years it was the stuff of scientists studying genetics and disease, but words and ideas such as genes and inheritance of traits have become part of common parlance.

The rapid growth in our understanding over the past 60 years, including the delivery of genomes for a range of species including humans, has affected all of us at some level. This knowledge has brought improved medical treatments, new drugs and better disease diagnosis. It has increased crop yields, is helping to raise the nutritional value of foods, and is helping to develop replacement tissues for worn-out joints. Here, three people working in different areas share their impressions of the discovery six decades on.


Rosita Boland
Irish Times feature writer

My first encounter with DNA occurred long before I understood what it was. I am the only red-haired person in my family, and became aware as a small child that this was somehow odd. Neither the generation preceding me, my own, or the one now following me has a rib of red hair between them. But red hair, that recessive gene, is in there somewhere in my combined DNA of Bolands and Comers: some long-dead relative has passed it on to me.

I find it almost impossible to comprehend the fact that physical likenesses can turn up generations later in families. I sometimes look at my nieces and nephews and wonder am I looking at clues to our long-dead, and mostly unphotographed relatives: jigsaws of genetics. It makes me feel dizzy, as does wondering if abstract characteristics of a person, such as courage, aspiration, kindness, grace and curiosity, can ever repeat themselves in similar ways. Is that an unscientific thought? Who knows?

But mostly, when I think about DNA, I marvel at how it has transformed forensic science. It enables the possibility of a second chance for justice being sought, often long after the crime has been committed. Retrospective justice no longer depends on Victorian ad-hoc deathbed-type confessions. Even the infinitesimally tiniest pieces of us – of our bones, blood, hair, skin or body fluids – can now constitute vital crime-scene clues to those who know how to read them.

DNA makes time fluid. Three generations later, a nose can be repeated like a motif down a genetic line. And it has the power to reel a person back in, through decades, even through death, to face truth about previously unsolved crime. I can still hardly believe these facts. It’s more like science fiction than the stuff of science.


Aoife McLysaght
Professor in genetics at Trinity College Dublin
The structure of DNA was once a mystery to be solved, but nowadays, kids might even have seen it in cartoons before they start school. Humans were once considered exempt from the rigours of natural selection, somehow separate and above mere animals, but today it is common knowledge that our DNA is almost identical to that of a chimp.

DNA was an elusive, mysterious molecule, but starting with the crystal photographs of Rosalind Franklin and Maurice Wilkins, and the towering models of James Watson and Francis Crick, it began to be revealed to us.

Most importantly, the structure of DNA revealed how it can be copied – each half of the double helix acting as a template. This beautifully simple mechanism carried DNA, encoding an increasingly complicated message, from the origins of life to the present day. Along the way, natural selection and the other evolutionary processes carved out the huge biological diversity all over this planet from a mess of genetic variation.

My own research is concerned with figuring out these evolutionary processes to learn how we came to be the way we are, and to see what that can teach us about the present and what opportunities it can offer for future research and medicine. I was involved in the Human Genome Project as a student, and since then many other animal genomes have been sequenced. By comparing these, we can see how the sequence of DNA changed over time in our extended (and humbling) family tree, reaching back to our simple ancestors.

Among other things, we are using the patterns of DNA change to identify “weak points” in the human genome, that might be susceptible to disease. The impact of the discovery of the structure of DNA on my work is a bit like the significance of the invention of celluloid film for a photographer – without it, there would be nothing.


Fiona Doohan
Molecular plant pathologist who studies plant genetics to improve plant resistance to harmful diseases

Plants are central to life on Earth and if we are to have enough food to feed the world’s population over the next few decades, we will need to double our crop yields.

Since the discovery of DNA, scientists have gained a huge amount of knowledge regarding the structure and function of plant DNA, enabling us to make great advances in plant genetics and improvements in food security.

The first plant genome was sequenced nearly two decades ago. Back then, DNA sequencing was laborious and costly, but today we have genome sequences for many crop plants.

The discovery of DNA has radically changed the way we breed and utilise crops and the means by which we recognise and protect our plant biodiversity. It has accelerated our ability to breed crops with desirable traits such as disease resistance, cold and drought tolerance.

In 2012, we saw the first genome sequence released for wheat, a crucial global source of human calories. My team’s research looks at diseases relating to Septoria tritici blotch and Fusarium head blight disease in wheat.

My research uses plant DNA technology to control the disease and to prevent the causal disease organism from contaminating the grain with toxins that are harmful to humans and animals.

Genetic modification of plants is one of the most controversial consequences of the discovery of DNA. We have the tools to insert foreign DNA into plants thereby changing their characteristics and benefitting food security. The debate is destined to continue as more and more countries cultivate GM foods.

GM has benefited medicine, as many drugs can now be produced in plants relatively cheaply. Who would have thought that we would be “pharming” human drugs in carrot cells?

 

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