 |
|
|
 |
DNA and cockroaches: like two peas in a pod |
| |
 |
 |
 |
 |
|
Scientists at ANSTO have discovered a new way to extract DNA from contaminated evidence. |
|
 |
|
It's been said that the indestructible cockroach would be the only species on earth to survive a nuclear war. Now, thanks to the work of scientists at the Australia Nuclear Science and Technology Organisation (ANSTO), fragments of DNA can join the unyielding bug in a quest for survival.
DNA can live in many fragments of our selves, skin, hair, saliva, dust, but in contact with radioactivity it can perish if left too long. This means that in the event of a radiological attack, biological evidence may be slowly destroyed by radiation making it extremely difficult for forensic scientists to trace the people responsible.
ANSTO's David Hill and PhD student Serena Abbondante from the University of Canberra are leading the fray in world-first scientific research which has developed a new method of extracting DNA from biological material contaminated with radioactive agents so vital evidence can be saved.
"If a crime is committed involving radioactive material and in the process the perpetrator leaves DNA behind, it's likely that it will be contaminated. So it's imperative that the DNA is preserved and this is best done by removing the DNA from the radioactive material," said David.
What makes the DNA extraction tricky is that the biological material (such as skin or hair) needs to be decontaminated without affecting the DNA contained in the material AND within a short time frame to avoid radiation damage to the DNA.
"You can't take contaminated samples into a normal laboratory not equipped to deal with radioactive samples or it will contaminate the surroundings and leave the laboratory unsuitable for analysis of inactive samples.
"To overcome this problem we use the extraction techniques developed by Serena as part of ANSTO's counter terrorism project to help Australia prepare, prevent, respond and recover in the event of a radiological incident," he said.
The development of this special technique came about by exposing a variety of biological samples, such as blood and bone, to radioactive agents and Serena compared different methods of decontaminating the evidence.
"The standard method of extracting DNA from biological evidence until now was the Chelex100 extraction procedure," explained Serena. "Chelex100 is an ion-exchange resin which can extract the DNA but cannot remove radioactive contaminants without further processing."
"I played around with a few methods and my research found that using a special magnetic resin in the process was the answer, and a much more effective method to purify DNA samples."
The first step in the DNA extraction procedure is to incubate the biological material in a solution containing magnetic resin. The resin provides a solid support for the DNA to bind and the liquid solution washes away and removes radioactive material and other contaminating materials from around it. The decontaminated DNA can then released from the magnetic resin into a clean solution so the DNA can be analysed.
Serena found that the greatest advantage the procedure provided was the ability to simultaneously extract and purify the DNA in a single step.
"It can also be automated, which may provide an additional level of protection from exposure for the analyst," she said.
By using the magnetic resin extraction procedure, the researchers observed approximately 99.99% removal of radioactive contaminants. Using Chelex100 there may be approximately 98.5% removal.
"While this may not seem like a great deal of difference, when you are considering analyst safety and dose limits, these small changes can actually have a substantial effect on the final dose rate," Serena explained. "As a result, this affects the number of samples able to be processed as well as the amount of time the analyst is able to physically work with the evidence."
Since the development of this, the technique has been provided and adopted by law enforcement agencies in the United Kingdom, the United States, Canada and Singapore.
According to Serena, the technique could be used in the crime scene reconstruction after the terrorist use of a 'dirty bomb', where radioactive materials are dispersed with the aid of explosives, or possibly for use in intelligence gathering at clandestine laboratories where manufacture of these devices take place.
"We need to recognise that these scenarios may pose unique challenges to existing forensic agencies as presently there is limited information on analytical methods or handling procedures for biological samples that are contaminated with radioactive materials," she concluded.
It is a comforting thought for the invincible cockroach then, that in the event of a nuclear attack, they are not alone.
|
|
 |
|
|
 |
|
|
 |
 |
 |
Extraction techniques, such as the one employed in this research, have been used for many years, however, it is only recently that it has been applied to the field of forensic biology.
|
 |
 |
|
These techniques can be used in a wide variety of fields ranging from toxicology to immunology, and can be applied in the isolation of numerous chemicals and proteins.
|
|
|
|
 |
|
Get it delivered
Learn how Australia's science in motion makes a difference to daily lives. Sign up today.
|
|
|
 |
|
