Please see our “Did You Know?” section toward the end of this issue.
Topic: DNA Amplification and Detection Made Simple
In reading a great number of articles regarding the development of DNA evidence use I find it interesting to see how much emphasis is continuously being put on certain topics. It seems that we read facts mixed with varied opinions on these same issues over and over again – yet, although they may be slow, there are new developments all the time.
Recurring topics are debates over increasing databases and whether a pending legislation has moved to a new level of government; funding for new laboratories; compensation for the wrongfully convicted; and the tremendous backlogs faced by many labs in the country.
As these issues continuously make headlines, on a case by case basis, we seem to be making strides. On the one hand, based on our backlogs, there are hundreds of thousands of cases that are unsolved, and new cases developing daily, yet the stories I read every day where DNA evidence is being put to good use are encouraging.
In addition, professionals in law enforcement are finding new sources of evidence from which DNA samples can be extracted, federal funding is becoming more available, scientists are developing new and more technologically advanced methods of DNA extraction and amplification, and forensics is becoming part of more and more high school and college level curriculums – a great indication of where the future is heading.
So as we continue to read about the big headliners, such as the issues addressed below – the number and types of cases which follow, indicate that we are in fact moving forward.
Commentary: In the Interest of Real Justice, DNA Must Be Used to Resolve Older Cases
Twenty-two years ago, Alan Newton was convicted of rape, robbery and assault. For 22 years, he maintained his innocence and, as a result, was denied parole. For nearly 12 years, Newton fought for DNA testing, certain it would clear his name. It did. And now Alan Newton is free. But he’s lost 22 years of his life -- years that he can’t ever get back.
While the government can’t make up for Newton’s lost time, it can do right by the thousands of men and women who have, for years, been rotting in cells around this country, holding on to their innocence. The criminal justice system must ensure that DNA testing be made available to defendants in older cases. There are sure to be many more Alan Newtons out there; they deserve a chance to be heard. DNA testing is a powerful tool that can be used to exonerate or convict accused criminals.
A fairly new phenomenon, DNA wasn’t widely used when Alan Newton was convicted. Years after his conviction, when testing became more popular, Newton had to literally fight the New York City police department to locate the evidence from the crime scene. Because so much time had passed or, perhaps they didn’t want to find it, the department had a hard time locating the evidence (turns out it was sitting in its original vault.). Across the country, there are thousands of defendants, convicted 20 or so years ago, fighting -- just like Alan Newton -- for the use of DNA testing in their cases. The courts, in the interest of true justice, should see to it that those requests be honored in a timely manner.
Two years ago, the University of Michigan examined more than 300 criminal cases, using 1989, the year of the first DNA exoneration, as a starting point. In more than half of the cases, the defendants had been in prison for more than 10 years and, in all cases, DNA was used to free the defendant. Researchers said that the data suggests there are thousands of innocent people sitting in our nation’s prisons.
DNA testing is not a perfect science. Much is left up to forces that can’t be controlled. However, with more and more people being exonerated by the testing, the criminal justice system should make it a priority to use the technology, whenever possible, in older cases. If someone was falsely convicted, the truth needs to be brought to light immediately.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref03.html
The Consortium of Forensic Science Organizations (www.theCFSO.org) applauds the efforts of Senator Richard Shelby (R-AL) and the U.S. Senate for supporting critical funding for all aspects of forensic science.
State and local crime laboratories are an integral part of the criminal justice system. Recent years have seen a dramatic increase in the demand on the labs for forensic testing of a variety of evidence types, but funding has not kept pace. Crime lab backlogs cause significant delays in evidentiary analysis, resulting in delays in the investigation and solving of crimes, as well as delays in the courts. At last check, the largest 50 laboratories in the U.S. more than doubled their backlogs of unprocessed evidence.
The forensics community praises Senator Shelby for his understanding of the current situation in all forensic areas, including controlled substances, latent prints and DNA.
The issue of funding forensic science is currently being debated in Congress, as part of the federal government's criminal justice budget for fiscal year 2007. The U.S. Senate Appropriations Committee has approved $18 million for the Paul Coverdell Forensic Science Act in the Senate Commerce, Justice, and Science Appropriations bill and an additional $175 million for DNA.
"Funding for our crime labs is a national issue at a critical stage. What you see on television is not reality," says Barry A. J. Fisher, Crime Lab Director for the Los Angeles County Sheriff Department. "Crime labs are running large backlogs and simply don't have resources to get results out in a timely basis. This federal money will be a great help," he stated.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref01.html
Louisianians arrested in cases of fighting with school referees, hiring a prostitute or stalking now will find their DNA in a national FBI database — alongside that of convicted rapists and murderers.
State Police on Tuesday uploaded to the National DNA Index System, or NDIS, the first batch of genetic profiles from 45,000 people arrested for — but not convicted of — felonies and certain misdemeanors.
Hailed by law-enforcement authorities but denounced by civil-liberties advocates, the move will more than double the number of residents whose genetic information is electronically accessible for criminal investigations.
“Louisiana can expect to have a big impact on solving crimes,” said Ann Todd, spokeswoman for the FBI Laboratory at Quantico, Va. “Obviously, the more information in the database, the more productive it will be in helping to solve crimes, and the types of crimes in the database are violent crimes typically.”
The state began taking DNA samples from those convicted of felonies in 1999, but in 2003 expanded its collection to include arrestees.
Just six other states — Virginia, Texas, Minnesota, California, New Mexico and Kansas — have similar laws. Last year, Congress said it was OK to take DNA from those arrested in federal offenses.
The FBI limited its national DNA database to profiles of those convicted of a felony until January, when President Bush authorized the inclusion of arrestee information as well.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref02.html
Cases involving the use of DNA evidence include:
Florida - Police have made an arrest in the fatal beating of a 73-year-old man in his home more than a year ago.
James Reese Thomas, 41, was charged Thursday in the beating of Christopher Brewington in a home on Ribault Scenic Drive on Feb. 22, 2005. Brewington was hospitalized and died two weeks after the beating.
Homicide investigators said the motive for the attack is still unclear, but the two men were acquainted. Officials said the arrest was made as a result of a DNA match of blood on a hatchet found in the home.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref04.html
California - A cold case for Lompoc detectives turns into a cold catch, after a rape suspect evaded authorities for more than six years.
The man who Lompoc police said sexually assaulted a 51-year-old woman and attempted to rape a 49-year-old is Derek Buncom, who is now behind bars.
"In both of those cases we were able to obtain DNA samples, and we were able to determine the DNA was the same in both cases," said Bill Brown, Lompoc police chief.
However, investigators were not able to identify who committed the crimes, so they put the samples into a California DNA database, but still nothing came up.
"It was a cold case hit," Brown said.
And then 2002 rolled around, when a national DNA database was established. Every suspect who commits a felony can be uploaded into the system.
"He was in custody in Alaska for a burglary charge," said Brown.
When Alaskan authorities uploaded Buncom's DNA in 2005, it was exactly what Lompoc police needed to extradite the suspect.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref05.html
Virginia - A "cold case" DNA match has aided getting a conviction recently in a rape that occurred 11 years ago in Woodbridge.
Kenneth Ray Bedard, 42, of Edgewood, Md., was convicted Monday in Prince William Circuit Court by Judge Frank A. Hoss Jr. of abduction, rape, forcible sodomy and use of a firearm in each.
On Oct. 20, 1995, a 27-year-old female real estate agent who was selling town homes near Gina Place was attacked and raped in a model home, according to police.
Police initially had no suspects in the case.
In 1996, forensic analysis found no DNA in the state database that matched evidence from the victim, according to court documents.
Bedard was indicted on the charges in March after his DNA was matched as a "cold hit" in a recent database search, according to court documents.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref06.html
California - A convicted rapist and a man accused of sexual assault are behind bars, and the key to revealing their identities was looking at something that was locked inside of them all along.
Troy Malray, 44, and John Wayne Smith, 45, were arrested after police in Santa Monica and in Northern California linked each man using DNA to the alleged crimes, which were committed separately.
Santa Monica Police said Malray – who was arrested Monday, June 17, in San Bernardino – is responsible for the beating and sexual assault of a local woman he held captive for half an hour at her seaside home in Santa Monica on September 1, 2005.
DNA taken from the scene that night was run through CODIS (Combined DNA Index System) and a positive match came up identifying Malray, who has an “extensive criminal history.” Malray also matched the description by the victim, Santa Monica police said.
For Smith – who was five months short of being paroled after 13 years of incarceration for the 1991 Santa Monica rapes of a mother and daughter – it was DNA evidence that led to a new charge of torture stemming from a Northern California attack 16 years ago.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref09.html
California - A bloody bathroom towel and bloodstains on a bedspread and eyeglasses case were sufficient evidence to require a Rancho Santa Fe real estate broker to stand trial for the 1986 stabbing death of a La Mesa woman, a judge ruled yesterday.
Advances in DNA testing techniques helped tie the bloodstains to Marc Exter Jernigan, who had dated the 19-year-old daughter of June George before George was stabbed to death in the kitchen of her Mariposa Street home Aug. 8, 1986, prosecutors said.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref10.html
Washington, DC - A rapist who preyed on Northern Virginia women could spend the rest of his life in prison after a hit on the DNA database last November.
A realtor said she was held at gunpoint and raped as she worked at a Woodbridge open house in 1995.
Kenneth Bedard, 42, of Spotsylvania County was found guilty Monday in Prince William County.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref11.html
California - A DNA match has enabled Alameda County Sheriff's deputies to arrest a convicted rapist in connection with three East Bay sexual assaults that occurred in the early 1990s, one of which involved torture.
James Dwayne Smith, 45, is already serving time at the San Luis Obispo Men's Colony for a rape conviction in Southern California. He has been extradited to Alameda County to face a torture charge for a 1991 case in which a 13-year-old girl was kidnapped, raped and tortured in unincorporated Hayward, according to a sheriff's news release.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref12.html
Washington - DNA from a suspect’s discarded cigarette led Pierce County prosecutors to charge a 20-year-old man Friday with the 2004 rape of a teenage girl in South Tacoma.
“This is just plain old good police work,” deputy prosecutor Mary Robnett said.
She charged Donald Robert Morgan with first-degree kidnapping and two counts of first-degree rape for the attack Nov. 22, 2004, on a 15-year-old high school student walking to her bus stop. He pleaded not guilty in Superior Court in front of Judge Bryan Chushcoff.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref13.html
California - No one could say for certain Armando Aguilar was behind the wheel of his pickup truck last summer when the vehicle was involved in a hit-and-run crash that killed one man and injured a second.
And even though Aguilar turned himself in to police three days later (with the help of his attorney), investigators were told there simply wasn't enough evidence to prosecute the case.
All that changed, however, after detectives went back to take a second look at the evidence.
What they found in the impounded truck were skin cells left on the air bag that deployed at the point of impact. After waiting nearly 10 months for test results from the Los Angeles County Sheriff's Department's crime lab, detectives said they learned this month that the DNA cells in the skin samples scraped from the air bag match those on a swab taken from Aguilar's cheek.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref14.html
California - Benicia police said a cold hit DNA match led to the arrest Tuesday of a Vallejo man on suspicion of raping a woman in Willow Glen Park in Benicia more than four years ago.
Sgt. John Daley said 21-year-old Robert Laron Bell was arrested for rape and violating his probation for possession of stolen property around 4 p.m. outside the Solano County Probation Department's office at 300 Tuolumne St. in Vallejo.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref15.html
Massachusetts - A Bristol County grand jury has indicted a convicted murderer in the 1992 killing of Gerald Rose, the Taunton city planner whose slaying stymied investigators for 14 years until a recent DNA match.
Rose, 39, was found strangled in his ransacked apartment by his mother on Feb. 18, 1992.
Bristol County District Attorney Paul F. Walsh Jr. announced today that Timothy Imbriglio, 35, has been charged with the crime.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref16.html
North Carolina - Authorities have run DNA tests and believe one man is behind a series of rapes in Raleigh and one that happened in Greenville.
A DNA analysis performed by the State Bureau of Investigation established that one man is responsible for five rapes that occurred in Raleigh during 2003 and 2004 and one rape that occurred in Greenville in 2005, Raleigh police said in a statement Friday.
"The link could be very valuable," said Major Ken Mathias, the commander of the RPD’s Detective Division. "Combined with the composites and other suspect information, the fact that the same man committed crimes in two cities may prompt someone to think about a potential suspect who resembles the composite and has spent time in Raleigh and Greenville."
Positively linking the five cases resulted from the SBI’s ongoing testing of rape kits from across the state that potentially contains DNA evidence, Raleigh police said. If DNA can be extracted from a particular kit, it is checked against other cases and against various databases to see if any matches can be established.
Anyone with information that might be helpful is asked to call the SBI at (800) 334-3000, the Raleigh Police Department at (919) 890-3555 or the Greenville Police Department at (252) 329-4348.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref17.html
Florida - A crime more than a decade old has been getting attention after the lawyers representing a man convicted of killing his brother's wife claim DNA proves their client does not belong behind bars.
The story began on April 17, 1994, when police investigated the scene of a murder in Mayport where they found the body of Tina Heins. Her 19-year-old brother-in-law Chad Heins was charged with the crime.
More than two years later, Chad Heins went on trial.
Prosecutors asked for the death penalty, but Heins received a life sentence.
Nine years after Chad Heins' murder trial, he maintains that he didn't kill his pregnant sister-in-law.
Recently, his lawyers announced that new evidence in the case has changed everything.
"I really believe if they had this DNA evidence 12 years ago, Chad never would have gone to prison in the first place," said defense attorney Nina Morrison.
Defense attorney's filed an 89-page motion asking a judge to free Heins based on new evidence. They said during the original trial, jurors never heard that hairs found on Tina Heins' body matched DNA found under her fingernails, and the DNA does not belong to Chad Heins.
Defense attorney's said the science doesn't lie, and Chad Heins should be a free man.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref19.html
California - A 19-year-old Long Beach woman was the victim of a home-invasion rape in July 2002, attacked repeatedly in her own bed with a pillow covering her face. She saw nothing; and without any witnesses or suspects, the rape was deemed almost unsolvable.
More than a year later, a "Peeping Tom" named Jose Estorgia Reyes, 35, admitted to burglarizing the apartments of two women in downtown Long Beach. As a result of a plea bargain, he received a four-year prison sentence and was ordered to provide his DNA to authorities.
A Los Angeles County crime lab matched that DNA to the sexual assault, said Long Beach Police Detective Craig Newland, who led the investigation. And on Wednesday, Reyes was convicted of three counts of rape during a residential burglary - each of which carries a maximum penalty of 25 years to life in prison - among other charges.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref20.html
Maryland - The woman with dark, wavy hair, pale skin and wide eyes sat board-straight on the courtroom bench. Toying with the necklace at her throat, she leaned in slightly to hear the prosecutor.
She was nervous, she would say later. Still not quite believing that she was sitting in the same room as the man identified by DNA evidence as the stranger who grabbed her on the street 25 years ago, put a long knife to her throat, dragged her into a dark yard and raped her.
The key to cracking the April 1981 case was hidden in the fabric of the underwear police took from the woman at the Greater Baltimore Medical Center that night. The clothing was carefully wrapped in brown paper and packed away in the basement of Baltimore County police headquarters in Towson, waiting for the day when investigators might have some use for it.
Twenty-two years later, they did. The DNA on the woman's underwear led police to prisoner No. 194706, Kevin Siler, 44, who has spent most of his adult life - but for a few months in 1981 - in Maryland prisons.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref21.html
Kansas - Police say DNA evidence implicates a man who’s charged in the deadly shooting earlier this year outside a downtown night club.
DNA swabs taken from the handgun believed to have been used in the Feb. 5 shooting matched the DNA swabs taken from the mouth of suspect Rashawn T. Anderson after his arrest, Lawrence Police Detective Zach Thomas testified this afternoon during Anderson’s preliminary hearing.
Anderson is charged with shooting and killing Robert E. Williams, 46, after an argument following a hip-hop show at the Granada, 1020 Mass. Today’s hearing was the first time details have emerged of the investigation that led to Anderson’s arrest.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref22.html
Ohio - Police believe they may have solved a series of Cleveland Heights rapes, some dating back more than 20 years…
From 1984 to 1986, people in Cleveland Heights lived in fear of the Cedar Hill rapist.
"He'd come out of the woods, grab them, cover them up, drag them back into the woods, rape them several different ways at knife-point and then take off running after he was done," said Cuyahoga County prosecutor Bill Mason.
Then suddenly, the attacks stopped. Almost 20 years went by without the rapist claiming another victim. It was about the same amount of time that suspect Clifford D. Jones, 47, was in prison for raping a young relative.
"He was sentenced to a nine to 25-year sentence. He served about 19 years of that sentence, got out in 2004. Within three months of being out he started his attacks on these women again on Cedar Hill," said Mason.
There were four more victims, including a 12-year-old girl. Once again, investigators were baffled.
Jones was sent back to prison for violating his parole after police said he was caught in a Warrensville Target store masturbating and watching young children.
A new state law forced Jones to submit a DNA sample, and it matched DNA found on his alleged victims.
"But for him going back to prison the second time when the state changed the law when they started swabbing all defendants going to prison, we would not have caught him," said Mason.
Jones will not face charges in the cases from the mid-80s because the statute of limitations has expired. He could still spend the rest of his life in prison if convicted on the other rape charges.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref23.html
Pennsylvania - Six days after arriving in the United States, a 56-year-old Indian woman was kidnapped from a Shadyside street, raped, robbed and shoved out of the vehicle on a corner in Garfield, according to videotaped testimony played yesterday in court.
Robert Hawkins Jr., 43, and Calvin Henderson, 58, a stepson and stepfather from Garfield, are on trial this week for the rape, robbery and abduction on June 19, 2005.
The prosecution connected Mr. Hawkins to the crime through a witness who picked him out of a photo array.
The most powerful testimony came, however, from the serologist who tested DNA samples from the rape kit, from the vehicle police believe was involved and from the two defendants.
No DNA evidence tied Mr. Hawkins to the crime; however, DNA extracted from the seat cushion and the steering wheel matched Mr. Henderson's. Two separate DNA samples from the victim rape kit matched Mr. Henderson's genetic profile, a one in 15 sextillion likelihood.
"You are one quadrillion times more likely to win the Powerball jackpot," said Robert Askew, the serologist. "You are 7.6 times more likely to win the Powerball twice than to have this profile."
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref24.html
Colorado - A man was charged with three incidents of sexual assault 12 years after the crimes due to DNA evidence.
Blias Reddin, 41, is accused of attacking an 84-year-old woman in May of 1994 and attacking a 56-year-old woman in June and August of 1994.
Reddin was previously accused of assault and is serving a 10-year prison sentence. His hearing for the new charges has not been scheduled yet.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref25.html
California - DNA testing has identified bones found 26 years ago near Needles as the remains of an Ohio man who has been missing for 33 years, San Bernardino County Coroner’s officials announced Wednesday.
Testing identified the man as Daniel Jobe Suffecool, of Canton, Ohio, who was 28 when he was last seen in July 1973, according to a coroner’s press release.
A wallet found alongside the remains in August 1979 led officials to believe they were Suffecool’s, the release stated, but the DNA testing based on saliva comparisons with Suffecool’s surviving siblings was the first proof.
The remains will now be returned to the family.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref27.html
Missouri - The evidence against Johnny Briscoe was overwhelming, and his alibi was flimsy. But the man sentenced in 1983 to spend decades in prison for rape was innocent.
Twenty-three years later, Briscoe walked out of the state prison in Charleston on Wednesday a free man after DNA testing at two labs confirmed another man was the rapist.
St. Louis County Prosecutor Robert McCulloch called the incarceration of Briscoe a "terrible mistake," one exacerbated by the county crime lab's failure to locate evidence when McCulloch first requested a review six years ago.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref07.html
California - A DNA sample has cleared a Fresno man, currently jailed on kidnapping charges, of a series of murders committed in Southern California, authorities said.
Inglewood Police Sgt. Steve Overly said Tuesday that a saliva sample taken from Roger Hausmann, 65, did not match evidence gathered in the homicides, which date back to the 1980s.
Source http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref08.html
Did You Know?
Topic: DNA Amplification and Detection Made Simple
Twenty-three years ago, a man musing about work while driving down a California highway revolutionized molecular biology when he envisioned a technique to make large numbers of copies of a piece of DNA rapidly and accurately. Known as the polymerase chain reaction, or PCR, Kary Mullis's technique involves separating the double strands of a DNA fragment into single-strand templates by heating it, attaching primers that initiate the copying process, using DNA polymerase to make a copy of each strand from free nucleotides floating around in the reaction mixture, detaching the primers, then repeating the cycle using the new and old strands as templates. Since its discovery in 1983, PCR has made possible a number of procedures we now take for granted, such as DNA fingerprinting of crime scenes, paternity testing, and DNA-based diagnosis of hereditary and infectious diseases.
As valuable as conventional PCR is, it has limits. Heat is required to separate the DNA and cooler temperatures are needed to bind the primer to the strands, so the reaction chamber must repeatedly cycle through hot and cold phases. As a result, the technique can only be performed in laboratories using sophisticated equipment.
Now Olaf Piepenburg, Niall Armes, and colleagues have come up with a new approach to DNA amplification that can be carried out at a constant temperature, using only a tiny amount of DNA, without elaborate equipment. Called recombinase polymerase amplification (RPA), the technique opens the door to dramatically extending the application of DNA amplification in fieldwork and in laboratories where PCR machines are not available.
RPA uses five main ingredients: a sample of the DNA to be amplified; a primer–recombinase complex, which initiates the copying process when it attaches to the template; nucleotides from which to form the new strands; a polymerase, which brings them together in the right order; and single-stranded DNA-binding proteins (SSBs), which help keep the original DNA from zipping back together while the new DNA is being made. The primer–recombinase complex is able to attach to the double-stranded DNA, eliminating the need to heat the mixture. After the complex is in place, it disassembles, allowing the DNA polymerase to begin synthesizing a new strand of DNA complementary to the template, while the SSBs attach to and stabilize the displaced strand. Under the right conditions—a precise milieu of process-regulating chemicals—the process automatically repeats, resulting in an exponential increase in the DNA sample.
The researchers tested the sensitivity, specificity, and speed of RPA by using it to amplify three kinds of human DNA, as well as DNA from Bacillus subtilis. They found it to be rapid and accurate. However, they also noted that using RPA to detect the presence of a specific type of DNA—for example, that of a specific pathogen—was complicated by the fact that, at low or zero concentration, the primer also produced an artifact effect (akin to some similar PCR artifacts). To counteract this, the researchers developed a probe-based detection method that causes the sample to glow in the presence of the DNA being tested for, but not in the presence of primer alone.
To demonstrate the usefulness of the new system, the researchers used it to test for the presence of methicillin-resistant Staphylococcus aureus (MRSA), a disease-causing bacterium known as a “superbug” because it is unharmed by penicillin antibiotics. They found that RPA could detect fewer than ten copies of MRSA DNA. It could also determine the presence of three different genotypes of MRSA, and distinguish them from a methicillin-sensitive S. aureus strain.
How easy would it be to apply such a test in real-life situations? The researchers demonstrated one possible approach by encapsulating the entire process in a dipstick that could be used in the field to detect the presence of a pathogen.
As great as the potential of RPA is for making DNA amplification and detection easier and more broadly applicable, that's not its only value. The researchers noted that the reaction environment they developed also provides a framework for improving understanding of recombination and the application of DNA hybridization.
Source: http://www.dnalabsinternational.com/email_newsletter/vol_23_jul_06/vol23_ref28.html
For more information and to read the research article, please go to:
Source: http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0040204
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