More great discoveries in the realm of science get stumbled upon by the unprepared mind than untangled by methodical research. dna fingerprinting, which has revolutionised forensic science since its development in the mid-1980s, is one such classic example. Sir Alec J Jeffreys, a leading biological scientist in the uk, chanced upon this novel technique while trying to develop markers to track the position of genes. He tells T V Jayan how it happened
You have been described as the father of dna fingerprinting technology. Can you tell us the genesis?
It all happened the way things usually happen in the field of science. By sheer accident. In 1977, I decided to move to the University of Leicester (in the uk). The primary area of our research interest there was the study of dna variation and evolution of gene families. We started off by doing some rudimentary genetic science, such as mapping chromosomes. Then we decided to identify variations in human dna. The idea was to develop a new breed of markers to track the positions of genes.
There are many repeat sequences in the genome, which are called minisatellites. Minisatellites contain certain core sequences and hence can be used to develop probes to detect regions of variable dna. In 1984, we decided to develop one such probe. Quite accidentally, we then stumbled upon something unique. Within five minutes of the film coming out of the developing room, by looking at the bands on the film, we had ideas about its forensic applications, its role in resolving paternity suits and immigration disputes. In fact, an immigration dispute was the first case that the technique was applied to. Thus, it was a chance finding that opened up a whole field of forensic dna typing.
What about applications other than forensic dna typing....
As it has shown, this was a novel and powerful generalised technology that could be applied to a wide range of problems in human and nonhuman genetics. It opened up all sorts of possibilities in animal breeding, conservation biology and ecological genetics. Many zoos have been using the original dna fingerprinting system to identify and establish family relationships within captive colonies of endangered species of animals and birds, so that inbreeding can be minimised and the genetic diversity of the species maintained.
What is the future of this technology?
The future, certainly for India, in the area of forensic science, is the tremendous potential for the development of an integrated national strategy for providing dna typing on a big scale. That, in a way, will help in carrying out a criminal database. Whenever a crime is committed and the perpetrator is caught, the dna sample of the person is added to the national database. This can significantly improve the resolving of criminal cases. Besides, with the improvement in the technology, the dna profile of a person can also serve as proof of one's identity. Hence, it can be used a security device. For example, your dna profile can be the key to opening your own house.
The human genome project has termed a substantial portion of the genome as junk dna....
One should very careful in calling them junk. How do you prove this or that dna is junk? You cannot. Take a piece of junk dna out, and what happens? That brings together two genes on either sides of the junk dna, which otherwise separated will now come together. So, the so-called junk dna has some spatial function. The term "junk" will not help, because we do not have a way of proving or disproving them "junk".
What are you currently working on?
We are looking at genetic mutations, and how environmental factors like radiation can trigger these changes. We've been studying the effect of radiation on mice and people after the Chernobyl nuclear reactor disaster. We found that radiation makes the genome unstable even in the offspring of people exposed to it. Which means new genetic mutations keep triggering in the children and grandchildren of people exposed to radiation, despite these children having never been near any radiation. The implied effect on humans is shocking.
Your team has been studying hotspots -- which are created by the concentration of crossovers between the human chromosomes. What role do hotspots play in the process of evolution?
We don't know yet what role the hotspots play in evolution. But, what we do know is how the hotspots influence the patterns of variability in populations. How they influence the natural selecton. So hotspots may be changing the way by which dnas have been evolved. We believe that understanding hotspots is important to understand mutation and recombination processes and how they impact on patterns of genetic diversity in human populations.
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