Category Archives: DNA

If you're on the paleo diet, you might want to rethink what you're eating. Not all Neanderthals ate a meat-and-fat paleo diet. In fact, some were vegetarians.

In a recent study, researcher Laura Weyrich and her team, from the University of Adelaide in Australia, examined the dental plaque and its DNA of five Neanderthal skulls to see what these folks used to eat.

According to The Atlantic:

Weyrich admits that science still isn't clear on how much we need to eat before it shows up in DNA, or whether some foods show up in DNA more than others.

But it seems a true paleo diet is simply foods in their natural state, whether it's a rump roast or a basket of sweet strawberries. Click here for the full story.

Photo: AguilaGib

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Neanderthal dental DNA shows us the true paleo diet (we've got it a bit wrong) - Boing Boing

RICHLAND COUNTY, S.C.

A 30-year-old cold case has been solved by DNA and a confession.

The Richland County Sheriff's Department's cold case squad says a man already serving multiple life sentences for killing four women in 1987 has confessed to another murder, that went unsolved for 30 years.

Patricia Ann Green's body was found on May 10, 1987, just steps away from the entrance of McEntire Air Base in Richland County. Sheriff Leon Lott said Green was shot multiple times and left in a culvert in a scene he described as "gruesome."

"It was a case that they had absolutely no leads on," Lott said. "At that time, we didn't know what DNA was. Our forensics back then was fingerprints. That was about it. The case was filed away, but not forgotten."

When the cold case squad reviewed the case last month, DNA found on Green's clothing was sent away for analysis. Testing found it matched Phillip Johnson, 53, who is already serving four life sentences for killing women in Sumer County. He was arrested for those murders in 1988.

When investigators approached Johnson, he confessed to killing Green.

"He gave information in his confession that only the killer would have known," Lott said. Johnson's explanation for the murders was chilling.

"There was no motive -- just that he was on a killing spree," Lott said. "She was just somebody he shot and killed."

Two of the women Johnson killed in Sumter County were killed before Green. The other two were killed after her death.

Johnson is being held at Kirkland Correctional Institution in Columbia. He has also been convicted of rape, kidnapping, burglary, armed robbery and assaulting a corrections employee, according to a report by The State.

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DNA, quadruple killer's confession solves SC cold case 30 years later - WYFF Greenville

DNA Can Do What Now?

Imagine storing every single byteof information that you have ever produced or owned on a single drive that you knew would be secure for hundreds upon thousands of years, flawlessly preserving the integrity of the data. This storage device isnt some sci-fi concoction. In fact, you already have access to trillions of such drives: your DNA.

Scientists Yaniv Erlich and Dina Zielinski from the New York Genome Center and Columbia University have published a paperthat outlines the process of encoding information into DNA and then decoding it for use using asystem dubbedDNA Fountain. They believe their technique could be used to store 215 Petabytes of data in a single gram of DNA thats roughly 2,859 years worth of high-definition video.

For their study, the teamstored an entire computer operating system, a movie, a gift card, and a few other files totaling up to 2,140,000 bytes in DNA oligos. This translated into 72,000 DNA strands, essentially just a specks worth. They were able to fully recover the information without even a single error in sequencing the data.

The teams research also confirmed their coding technique can be used to created a seemingly unlimited number of error-free copies of files. Not only that, but copies of the copies were also free of errors.

While the experiment only usedaround 2 MB of data, the project illustrated DNAs reliability in data storage and confirmed that the DNA Fountain algorithm couldencode binary information into DNA. However, this isnt the first time researchers have worked toward DNA computers.

Scientists at the University of Manchester have created a DNA computer that grows as it computes,while Harvard scientist George Church encoded 70 billion copies of his book into DNA. Companies such Microsoft are also looking to synthesizing information into DNA as a potential leap into a post-silicon world. With the movement forming, DNA computing seems like a natural fitfor the computingneeds of tomorrow.

However, the process isnt cheap. The DNA Fountain team needed $7,000 just to synthesize the 2 MB package, while also using another $2,000 in funds to sequence the information. Erlich believes that it will take more than a decade before the general public starts storing its information onto the blueprint of life itself, and even then, the revolutionary storage device might just be reserved for medical systems and not our personal mp3 files.

In the meantime, well just have to make do with our standard hard drives.

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Scientists Have Stored 2 MB of Data in a Single Speck of DNA - Futurism

By Christina Farr 03.08.17 | 7:00 am

Gerneiva Parkinson grew up in Trinidad and Tobago, a Caribbean nation off the coast of Venezuela known for its mangrove swamps and lush rainforests. But for Parkinson and many other young women, island life had a dark side.

Throughout her childhood, Parkinsons friends mothers and other women in the community were mysteriously getting sick in their thirties and forties. The diagnosis, as she later learned, was breast cancer. These are women with young children dying in their prime, but its common in Trinidad, she tells me. Infectious disease is well-studied, but cancer was, and still is, very taboo.

I met Parkinson at the headquarters of Color Genomics, a Silicon Valley-based startup founded by former Google and Twitter executives. Parkinson was invited to the companys offices to deliver a presentation on the high rates of breast cancer in her home country, and her journey to understand the roots of the disease. When it came to cancer, it has been really hard to get answers, even as a biology student, Parkinson explained to the team.

Color Genomics is one of a growing number of U.S. companies that leverage DNA sequencing to answer a wide variety of questions about disease. The price of such technologies have dropped significantly over the past few decades. In 2001, it cost $100 million to sequence a human genome. Today, Color offers one of the cheapest offerings on the market, with a test to screen for a set of genes associated with hereditary cancers for just $249.

Gerneiva Parkinson receives a $250,000 research grant at Color Genomics in South San Francisco, California.Photo: courtesy of Color Genomics

Thus far, this kind of technology is still limited to the wealthiest nations, such as the U.S. and European countries, where testing is common among those with a family history of cancer or an early diagnosis. In the U.S., screening has really been incorporated into routine care for breast cancer, says Erin Hofstatter, a medical oncologist based in New Haven, Connecticut. The presence of the gene mutation is by no means a death sentence. Many informed patients seek highly effective preventative treatments to reduce the likelihood that theyll ever get sick.

For the most part, these screening tools have not reached Trinidad and Tobago. Few women in the country get tested for known cancer mutations due to the lack of awareness among doctors and patients, as well as the high price of tests. Parkinson realized a few years ago that before she could push the local Ministry of Health to change that, she needed hard data. At that point, Parkinsonwho was still a medical studenttook the unusual step of creating a study of her own.

Well before she made the connection with Color Genomics, Parkinson was awarded a research fellowship with a small amount of funding to study the breast cancer problem in Trinidad. After going door to door, she was able to raise additional capital from her parents and a handful of small local businesses. The target initially was to test 350 women, but Parkinson only had enough to pay for 60.

Still, she moved ahead with her goal to recruit a sample set of breast cancer patients from diverse backgrounds. Trinidads ethnic makeup is divided into three main categories: Those with African heritage, who were descended from slaves; East Indians, whose ancestors were laborers from the Indian subcontinent; and people of European descent.

After successfully testing the first cohort, she and Hofstatter nervously awaited the results. Both were expecting that the gene mutations would be found in no more than five patients, and that the results could be delivered ad hoc via phone. In the U.S., Hofstatter tells me, the prevalence rate is about 5% to 10%, and studies typically involve thousands of patients.

When the results came back with 15 patients, I was like, Oh my God, thats 25%, recalls Hofstatter. The researchers also discovered that it was more than just one or two gene mutations. Hofstatter immediately agreed to fly out to the country to speak to the study participants in person.

Parkinson knew that more extensive research would be necessary to convince the government to routinely pay for screening, and contacted Color Genomics to inquire about its affordable tests. The companys head of partnerships, Alicia Zhou, recalls being impressed with Parkinsons efforts: She was a medical student taking on the burden of a country.

The Color Genomics founders agreed to fly out a few team members, including Zhou, to meet with locals and better understand the challenges. The objective for us all along was to format a study that could be used to lay the groundwork for future testing, Parkinson explains.

For Color Genomics, the partnership offered an opportunity to expand genetic testing around the world. After the trip to Trinidad, the company awarded Parkinson its first research grant for $250,000 and volunteered its own genetic counselors to train local physicians. I was invited to watch as Parkinson received her award, as her parents tuned in via Skype.

Parkinson is well aware that the tasks ahead wont be quick or easy. The infrastructure that is required to move the country from a system of treatment to prevention includes access to genetic counselors; breast MRIs; reimbursement for preemptive mastectomies; funding for public health campaigns; education for primary care doctors; and more. Parkinson is also hoping to fund studies into other forms of cancer, including prostate cancer, which are also more prevalent in the islands than in most areas.

In the final moments of our meeting, I ask Parkinson and Zhou a nagging question thats been on my mind since I first heard about the breast cancer rates in Trinidad: Why? Both have theories, but no conclusive answers.

Its possible that theres an environmental cause, although that would require further public health research. As Zhou explains, there also doesnt appear to be a single founder effect, a term that refers to the loss of genetic variation that occurs when a new population is established by a small number of individuals from a larger population. Instead, the answer might be related to the ethnic diversity from decades of colonial rule: Tobago changed hands more frequently between 1650 and 1814 than any other Caribbean territory.

I think with the influx of the French and the Spanish and the Africans, these mutations happened and they never left the population, Hofstatter later explained to me by phone. Trinidad and Tobago is a small and relatively isolated country, which makes it harder for the mutation to randomly disappear within a family. Once you introduce a mutation, its really hard to get rid of it.

Christina Farr is a San Francisco-based journalist specializing in health and technology.Before joining Fast Company, Christina worked as a reporter for VentureBeat, Reuters and KQED.

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How This Medical Student Brought DNA Testing To Women In Trinidad and Tobago - Fast Company

March 8, 2017 Hybrids between Blue-winged and Golden-winged warblers -- sometimes called "Brewster's" warblers -- pose a challenge for ornithologists trying to agree on how to define species. Credit: Lloyd Spitalnik

What is a species? Biologistsand ornithologists in particularhave been debating the best definition for a very long time. A new commentary published in The Auk: Ornithological Advances proposes a novel concept: that species can be defined based on the unique coadaptations between their two genomes, one in the nuclei of their cells and the other in their mitochondria.

All animals have two sets of genes, one in the cell nucleus and one in organelles called mitochondria, and these two sets of DNA work together to enable cellular respiration and energy production. If they're mismatched, the result is reduced energy output and increased production of damaging free radicals. While the most commonly used species definition is based on the idea that isolated populations slowly accumulate changes in their nuclear genes that make interbreeding impossible, Auburn University's Geoffrey Hill proposes a new twist on the species conceptthat speciation is really the divergence of sets of coadapted mitochondrial and nuclear genes. Interspecies hybrids, his theory suggests, have reduced fitness due their mismatched genomes' reduced ability to work together in the cell.

Past studies have shown that mitochondrial genotype tends to be very good at showing species boundaries between birds. This "mitonuclear compatibility species concept" helps explain the fact that the abrupt transitions between mitochondrial genotypes at species boundaries correspond with abrupt transitions in songs, plumage patterns, and female mating preferences. Interestingly, two closely related species that have recently been documented to have extensively intermingled nuclear genesBlue-winged and Golden-winged warblersalso show an abrupt transition in mitochondrial genes.

"Almost all ornithologists who write and think about avian speciation study phylogeographythe geographical distribution and genetic structure of bird populations," says Hill. "In contrast, I study bird ornamentation and, particularly, bird coloration. It was the discovery that ornaments signal mitochondrial type that led to my sudden realization that mitochondrial typeor, more accurately, coadapted sets of mitochondrial and nuclear genesdefine species boundaries. I don't think I would have ever seen the pattern if I had come at the question from a phylogeographic perspective."

"This is an intriguing and controversial ideathat mitonuclear incompatibilities could be so central to generating new avian speciesand I see this as a call for more research into how these incompatibilities might manifest themselves in young species," says avian evolutionary biologist David Toews of Cornell University. "The functional aspects of mitochondrial genes have, in particular, received little attention from the ornithological community, and it will be interesting to see how these ideas play with additional empirical studies going forward."

Explore further: The science of replacing mitochondrial DNA and what remains unknown

More information: "The mitonuclear compatibility species concept," The Auk: Ornithological Advances, March 8, 2017, americanornithologypubs.org/doi/full/10.1642/AUK-16-201.1

Provided by: American Ornithological Society Publications Office

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A new study by G. William Arends Professor of Microbiology at the University of Illinois Bill Metcalf with postdoctoral Fellow Dipti Nayak has documented the use of CRISPR-Cas9 mediated genome editing in the third domain ...

A new study involving biologists from Monash University Australia has found that despite their very different ancestors, dolphins and crocodiles evolved similarly-shaped skulls to feed on similar prey.

Proteins, those basic components of cells and tissues, carry out many biological functions by working with partners in networks. The dynamic nature of these networks - where proteins interact with different partners at different ...

New research from the University of St Andrews has sparked debate about what it takes to live in stable, long-lasting social groups.

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New species concept based on mitochondrial & nuclear DNA coadaptation - Phys.Org

Gif: ScienceRobotics

Living things: Theyre mostinspiring, but also difficult things to try to replicate in robotics. With that aim, researchers in Japan have managed to designa tiny robotic system that moves like a living cell. The scientists described the robotlast week in the journal Science Robotics.

The system, called a molecular robot, is about the size and consistency of an amoeba. It is a fluid-filled sac containingonlybiological and chemical componentsabout 27 of them,says Shin-ichiro Nomura, abioengineer at Tohoku University in Sendai, Japan and one of the robots inventors. The molecular componentswork in concert tostretch and change the shape of the sac, propelling it with cell-like motion through a fluid environment. The motioncan be turned on and off with DNA signals that respond to light.

Other than puttering around, the amoeba-like robot cant do much. But thats the beauty of the invention, says Nomura. The bot serves as a vehicle to house whatever researchers can dream up: tiny computers, sensors, and even drugs.Outfitted with those tools, the system could then be used to explore the biomolecular environment. It could seekout toxins or check the surface of other cells or the content of a Petri dish.

Nomura and his colleagues have figured out a way to package and ship the tool as a kit so that other scientists can play with the robots and incorporate their own components, he says. He hopes the platform will be used to build increasingly complex molecular robots with controllable motility.

Ultimately, Nomura would like to seethe robot function inside a cell. Thats kind of a frontier,says Nomura. A robot that can dive into a cell and itsnucleus can act as a diagnostic, seeking out problems with cellular machinery. Its a little dreamy,Nomura says, but notes that his robot can bereduced in size to less than one micrometersmallenough to fit inside a cell.

Researchers have developed many proof-of-concept micro- and nanoscale robots that can move and communicate within the body. Many of these tiny robots are made with biodegradable materials and are driven by magnetic, chemical, or ultrasonic forces.

Nomuras molecular robot differsin that it is composed entirely of biological and chemical components, moves like a cell, and is controlled by DNA. Other molecular robots have been developed, but none with this kind of controllable motility, Nomura says.

It took about a year and half and 27 different chemical components to make the molecular bot, Nomura says.Alipid membrane serves as a the malleablerobot body. Inside, specialproteins bump into the membrane, causing it to change shapekind of like bagbeing punched from the inside.

The punchingonly happens when key proteins called kinesins and microtubules connect to the membrane viaanchor units. That connection is provided by light-sensitive DNA. When UV light shines on therobot, the light-sensitive DNA inside cleaves into a single strand. It can then latch onto the anchor units and the kinesin-microtubule structure, forming a bridge between them.

The microtubules, which are rigid, long structures, slide along the kinesin proteins with the help ofadenosine triphosphate, or ATPthemolecule of intracellular energy transport. As they slide, they punch the bots outermembrane, causing it to change shape.

With this combination of molecules,Nomura and his colleagues succeeded in mimicking the movement of a cell. But if the thing is assembledsolely withbiological components and chemically powered by ATP,can we really call it a robot?The definition of robot is wide, says Nomura. If something has a body and can sense and process information to carry outa function,its a robot, he says.

Robot orcell-bot, we look forward to seeing what engineers stick inside it.

IEEE Spectrums biomedical blog, featuring the wearable sensors, big data analytics, and implanted devices that enable new ventures in personalized medicine.

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Amoeba-Like Robot Programmed With DNA - IEEE Spectrum

Scientists have developed what they claim is the most efficient data storage technique ever, with a new DNA-encoding method that approaches the theoretical maximum for information stored per nucleotide.

Using an algorithm called DNA Fountain, the researchers squeezed six files into a single speck of DNA including a short film, an entire computer OS, and an Amazon gift card but that's just for starters. The team says the same technique could effectively compress all the world's data into a single room.

Not only is DNA data storage an amazing space saver; the technique could also enable us to preserve knowledge with extreme robustness and longevity unlike traditional technology media, which is known to succumb to all kinds of faults with time.

"DNA won't degrade over time like cassette tapes and CDs, and it won't become obsolete if it does, we have bigger problems," says computer scientist Yaniv Erlich from Columbia University.

DNA storage itself isn't new, with the technique pioneered in 2012 by researchers at Harvard University, who figured out how to compress a 53,400-word book into the genetic code of synthetic DNA molecules, and then read the data back using DNA sequencing.

Since then various other teams have been trying to optimise the technique, with Microsoft claiming last year that a method it had come up with was 20 times more efficient than the previous record.

In turn, Erlich and fellow researcher Dina Zielinski from the New York Genome Centre now say their own coding strategy is 100 times more efficient than the 2012 standard, and capable of recording 215 petabytes of data on a single gram of DNA.

For context, just 1 petabyte is equivalent to 13.3 years' worth of high-definition video, so if you feel like glancing disdainfully at the external hard drive on your computer desk right now, we won't judge.

At the heart of the researchers' system is an algorithm originally designed to detect and fix errors in streaming video applications.

According to the researchers, the same kind of mechanism can be used to avoid errors when reading back binary data (made up of 1s and 0s) that's been translated into the four nucleotide bases in DNA: A, G, C, and T.

"[N]ot all DNA molecules are created equally," Erlich told Dexter Johnson at IEEE Spectrum.

"If you have DNA molecules that have a long stretch of the same nucleotide, such as AAA, it is not very favourable for the informatics machinery. It's very hard to read this molecule without an error. So you want to avoid stretches like that."

The researchers' algorithm manages to avoid errors when reading back the DNA data by additionally encoding a series of hints about what the information should look like once decoded.

This mean that not only can you recreate any DNA fragments that get lost in the process it's also highly optimised.

"We showed that we can reliably store information on DNA, and that our organising of information approaches 'optimal packing,'", Erlich told Katherine Lindemann at ResearchGate, "meaning it is nearly impossible to fit more information on the same amount of DNA material."

To test the system, the team compressed six files: a computer OS; an 1895 French short film, Arrival of a train at La Ciotat; a US$50 Amazon gift card; a computer virus; a Pioneer plaque; and an academic paper by information theorist Claude Shannon.

The overall file size of the complete package was relatively tiny coming in at just 2MB but the important thing was testing to see if the DNA Fountain algorithm was able to encode the binary information into genetic data without losing any of the information.

After the digital data represented in a list of 72,000 DNA strands was converted into a speck of DNA molecules carried in a vial, the researchers were able to sequence the DNA and recover the files with zero errors.

While it's an impressive result, the team says it will be some time before the expense of storing and reading data in DNA makes sense for the rest of us. For their 2MB package, the researchers spent $7,000 to synthesise the DNA, and another $2,000 to sequence it.

Erlich thinks it could be more than a decade before DNA storage becomes accessible to the general public.

And even then, the technology might be reserved for things like recording patient data in medical systems, as opposed to being sold to consumers as the latest tech product.

"This is still the early stages of DNA storage. It's basic science," Erlich told Eva Botkin-Kowacki at The Christian Science Monitor.

"It's not that tomorrow you're going to go to Best Buy and get your DNA hard drive."

The findings are reported in Science.

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Scientists Have Stored a Movie, a Computer OS, and an Amazon Gift Card in a Single Speck of DNA - ScienceAlert

Newly discovered DNA enhancers help switch on colorectal cancer Science Daily In a breakthrough study published in Nature Communications, scientists discovered changes in specific regions of DNA, outside of colorectal cancer genes, that "enhance" harmful gene expression to help grow tumors. The changes are highly conserved ... and more »

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Newly discovered DNA enhancers help switch on colorectal cancer - Science Daily

wbur

March 07, 2017Updated 03/07/2017 2:22 PM

Telling one identical twin from another poses problems for police. And it goes beyond appearances.

That's because DNA profiling may be the gold standard for bringing criminals to justice, but when it comes to identical twins, standard testing cant tell the difference.

So when crime scene DNA showed a match to a suspect in two rape cases in Boston in 2004, it showed a match to his twin brother as well.

Now, aSuffolk County prosecutor is trying to persuade a state judge to make her court the first in the country to admit a new forensic test that points to one of the twins and not the other.

The Scientific Legal Loophole Of Identical Twins

The case of 36-year-old Dwayne McNair of Dedham demonstrates the already long and powerful reach of DNA science that first came to a courtroom trial in 1987.

And Suffolk County prosecutors hope to extend that reach even farther.

The issue begins with thesavage and separate assaults of two women abducted, pistol-whipped and raped by two men in Dorchester.

Prosecutor David Deakin said that as the victim of the second assault was putting her clothes back on, she did something extraordinarily brave.

"Nearby was a used condom that one of the perpetrators had used during the sexual assault," Deakin said, "and she scooped the condom up in the cups of her bra, and then put the bra in her pocket."

That gave police a semen sample from the unknown rapist and thus a DNA "fingerprint." Several years later, when a couple of Boston cops got a tip that McNair might be worth investigating, they tailed him to work. They watched him smoke a cigarette, then picked up his discarded stub-- the source of another DNA fingerprint. It matched the DNA in the condom.

Case solved, you might think. Except the detectives learned McNair has a twin brother.

"We obtained a court order for the twins to submit DNA samples, which they did," Deakin said, "and the DNA testing of those samples revealed that they are in fact identical twins. And therefore both of their DNA matched the crime scene sample."

Here was the scientific legal loophole of identical twins: The prosecution could prove to a jury that it was either Dwayneor Dwight McNair who committed the crimes. But it couldn't prove which one.

"Ordinary DNA science, the kind of science that's used around the world every day in courts to identify people, can't differentiate between identical twins," Deakin said.

Scientists in general accept that not every cell in identical twins is exactly alike, that identical twins arent exactly identical. But its been widely assumed there was no way to tell them apart.

"The understanding was that you just couldn't do it," said Penn State law professor David Kaye, an expert in forensic science, "because they were so similar that the kinds of differences that genetic tests that are used in forensics would pick up just wouldn't be seen in any pair of identical twins."

'Next Generation' Sequencing

Ten years after the crimes, in 2014, Dwayne McNair was about to go to trial when prosecutor Deakin read about advanced technology successfully applied by a German company to tell one identical twin from another.

"Next generation," or "massive parallel," sequencing, as its called, enables scientists to map out the genome of each twin. That's the entire set of genetic instructions in the bundles of DNA the chromosomes found in every cell.

The goalis to findmutations, those rare events in the process of cell division that occur while each cell is otherwise faithfully copying some 3billion letters of genetic code. Inevitably, as with every typist, there's going to be a typo.

"You can have a miscopy, if you will, at some point in the DNA sequence," Kaye said. "We'll callthat a mutation."

Mutations occur both randomly and rarely. And if a mutation occurs after the twinning process, that gives rise to separate identical twin; its thought that the mutation will show up in one twin or the other, but not both.

In its experiment with identical brothers, that German company, Eurofins Forensic, used semen samples to map out the genomes of each twin. When it compared the two genomes, it found five mutations in one twin that were not in the other, thereby demonstrating identical twins could be differentiated.

Then Eurofins sequenced the genome of a child of one of the two brothers on the basis of a blood sample. Researchers found the child had the same five genetic mutations found in one of the identical twins, indicating who was the father and who was the uncle. The experiment offered evidence that mutations will carry to body tissue and semen.

Deakin realized the possibility the Eurofins test could compare the sperm sample of the unknown suspect with the saliva of the two McNair brothers.

"What Eurofins did was the first to publish a study showing that using this technique, you can identify the source of an unknown sample," Deakin said.

With time running out before Dwayne McNair went to trial in Boston in 2014, the Suffolk County district attorney hired Eurofins to test the McNair brothers saliva samples and the semen from the crime scene. And Deakin went to court to withdraw the charges against Dwayne McNair to wait for the results of genome sequencing on the twins.

They found nine differences out of 3 billion.

Now came the novel and controversial part of the test. After establishing the genetic differences, Eurofins compared both DNA profiles from the saliva with the DNA of the semen found in the suspect's condom.

Analysts found seven locations where the DNA of Dwayne McNair's saliva showed a match, and two where his brother Dwight matched.

Even more telling, scientists found two of the mutations in Dwayne's saliva were also present in the semen sample. In Dwights case, none were present.

On that basis, Eurofins concluded Dwayne McNair was 2 billion times more likely than Dwight to be the source of the semen and therefore the rapist. And in September 2014, Dwayne was once again indicted on charges of rape and armed robbery.

Ready For 'Prime Time'?

McNair's defense was to try to exclude the new tests and evidence from trial.

RobertTobin, his attorney, characterized the defense by saying"that the test isn't ready yet for forensics."Tobin added: "It hasn't been vetted and researched by independent scientists. ... I mean, its an interesting experiment but it just isn't ready for prime time."

In hearings over the course of three weeks and just concluded, the defense and the prosecution called to the stand a string of molecular geneticists, biostatisticians, embryologists, forensic experts and a former top scientist at the FBIs DNA lab.

McNairs defense established that the technique that implicates him has never been admitted to a courtroom anywhere in the world. Its the product of only one experiment using only one set of twins. There has never been a DNA study of, say, 20or a hundred sets of identical twins, published and peer-reviewed, to corroborate the findings or the foundations of what Eurofins has done.

"Given the way that most forensic tests are validated, and should be validated according to many scientists, this test has not been validated yet in that manner," professor Kaye said.

One of the most complicating and controversial issues is that the DNA of the sperm is being compared to the DNA from saliva.

Professor David Housman of MIT, who has a long history of testifying for the prosecution, testified this time for the defense.

"If they had obtained semen samples from both twins and one of the twin's semen samples matched the crime scene samples, then I would not have a problem with it," Housman said.

It would be far simpler if scientists could sequence the DNA of both twins' semen and then match them against the semen taken from the crime scene. But compelling someone to provide semen samples would be a violation of his Fourth Amendment rights against unreasonable search and seizure. So saliva samples, considered minimally intrusive, had to substitute as a proxy tissue. And witnesses questioned whether the saliva and the semen all have the same DNA.

"The issue of which twin is necessarily the donor of the sperm cannot be ... proven beyond a reasonable doubt," Housman said.

This isn't the first time Deakin has prosecuted a rape casecomplicated by identical twins both matching the DNA. But his expert witnesses testified to the rock solid quality of the technology.

Deakin has confidence in the evolving science.

"While it is indisputably a novel approach, we expect to prove its a reliable one," he said.

Now Superior Court Judge Linda Giles must decide whether the test and its results are ready for prime time.

If the prosecution is denied the use of the new evidence, it will still have the evidence from conventional DNA testing that narrows the suspects to one brother or the other.

But the prosecution will also have as a witness a man who has admitted to being the other rapist of the two women in this case.

In still another example of the far reaching power of DNA, that defendant was identified by a national DNA database, which showed he matched the DNA in a rape kit from one of the victims.

Correction:An earlier version of this story incorrectly reported Robert Tobin's first name. We regret the error.

This story aired on March 7, 2017.

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Standard DNA Testing Can't Differentiate Between Identical Twins. A New Test Challenges That - WBUR

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Scientists store digital files in an unlikely place: DNA - Mashable