Category Archives: DNA

Researchers have long sought an efficient way to untangle DNA in order to study its structure -- neatly unraveled and straightened out -- under a microscope. Now, chemists and engineers at KU Leuven, in Belgium, have devised a strikingly simple and effective solution: they inject genetic material into a droplet of water and use a pipet tip to drag it over a glass plate covered with a sticky polymer. The droplet rolls like a ball over the plate, sticking the DNA to the plate surface. The unraveled DNA can then be studied under a microscope. The researchers described the technique in the journal ACS Nano.

There are two ways to decode DNA: DNA sequencing and DNA mapping. In DNA sequencing, short strings of DNA are studied to determine the exact order of nucleotides -- the bases A, C, G and T -- within a DNA molecule. The method allows for highly-detailed genetic analysis, but is time- and resource-intensive.

For applications that call for less detailed analysis, such as determining if a given fragment of DNA belongs to a virus or a bacteria, scientists opt for DNA mapping. This method uses the longest possible DNA fragments to map the DNA's 'big picture' structure.

DNA mapping can be used together with fluorescence microscopy to quickly identify DNA's basic characteristics.

In this study, researchers describe an improved version of a DNA mapping technique they previously developed called fluorocoding, explains chemist Jochem Deen: "In fluorocoding, the DNA is marked with a coloured dye to make it visible under a fluorescence microscope. It is then inserted into a droplet of water together with a small amount of acid and placed on a glass plate. The DNA-infused water droplet evaporates, leaving behind the outstretched DNA pattern."

"But this deposition technique is complicated and does not always produce the long, straightened pieces of DNA that are ideal for DNA mapping," he continues. It took a multidisciplinary team of chemists and engineers specialised in how liquids behave to figure out how to optimise the technique.

"Our improved technique combines two factors: the natural internal flow dynamics of a water droplet and a polymer called Zeonex that binds particularly well to DNA," explains engineer Wouters Sempels.

The 'rolling droplet' technique is simple, low-cost and effective: "We used a glass platelet covered with a layer of the polymer Zeonex. Instead of letting the DNA-injected water droplet dry on the plate, we used a pipet tip to drag it across the plate. The droplet rolls like a ball over the plate, sticking the DNA to the plate's surface. The strings of DNA 'captured' on the plate in this way are longer and straighter," explains Wouters Sempels.

To test the technique's effectiveness, the researchers applied it to the DNA of a virus whose exact length was already known. The length of the DNA captured using the rolling droplet technique matched the known length of the virus' DNA.

The rolling droplet technique could be easily applied in a clinical setting to quickly identify DNA features, say the researchers. "Our technique requires very little start-up materials and can be carried out quickly. It could be very effective in determining whether a patient is infected with a specific type of virus, for example. In this study, we focused on viral DNA, but the technique can just as easily be used with human or bacterial DNA," says Wouters Sempels.

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Untangling DNA with a droplet of water, a pipet and a polymer

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Advanced Warfare - "CHAMPION CAMO" DNA BOMB - New GOLD Animated Camo! (AW Champion Camo Gameplay) - Video

Whats your DnA: Meet Bob
Do you aspire to be exposed to a multi-cultural environment, build a global career and travel? Meet Bob whose experience with Accenture has taken him beyond ...

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Whats your DnA: Meet Bob - Video

DNA: Arvind Kejriwal to meet PM Modi on Thursday
Arvind Kejriwal will meet PM Narendra Modi at 10:30 am on Thursday. Modi had also invited Mr Kejriwal for a #39;chai pe charcha #39;. The Prime Minister had called ...

By: Zee News

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DNA: Arvind Kejriwal to meet PM Modi on Thursday - Video

DNA: A look into AAP #39;s free Wi-Fi promise in Delhi
The AAP manifesto promised to open 20 new colleges, a 50 per cent reduction in power tariff, clean drinking water at affordable prices and a free Wi-Fi zone,...

By: Zee News

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DNA: A look into AAP's free Wi-Fi promise in Delhi - Video

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AW | Double DNA Bio Lab | free to use! - Video

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1 DNA 1 ATTEMPT (ep.1) - Video

FAMILY DNA...DID MY HUSBAND HAVE A BABY WITH MY SISTER? - Extended Promo
On today #39;s Maury, Lakeesha says a night of pleasure with DeAngelo has caused her 3 years of drama. After having a one night stand, Lekeesha got pregnant and ...

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FAMILY DNA...DID MY HUSBAND HAVE A BABY WITH MY SISTER? - Extended Promo - Video

DNA evidence suggests the hunter-gatherers of Britainwere importing wheat from their agrarian neighbors on mainland Europe as much as 8,000 years ago.

The discovery, publishedThursday in Science, could meanthere was more contact betweenearly farmers and hunter-gatherers in Europe than was previously thought.

According to the archaeological record,farming first started in Europe in the Balkans about 9,000 years ago and slowly moved west over the following millenniums, eventually coming to mainland Britain about 6,000 years ago.

But in the recent study, researchers studying ancient submergedsediment cores off the Isle of Wightfound evidence of wheat DNA in soils that date back 8,000 years ago.

So what is going on?

The research team, led by Robin Allabyof the University of Warwick,saythat whilethey found evidence of wheat DNA in the soil, they could not findany trace of wheat pollen. That leads them to conclude that while wheat was eaten on the site, it was not grown there.

"In the absence of direct evidence, we suspect that this wheat represents food stuffs imported from the continent," the authors write.

But there is a snag here too: The authors note that there is a 400-year gap between the age of the soil in which the wheat DNA was found and the earliest known presence of farming in nearby European sites.

In the paper, they propose that earlier agrarian sites may be submerged in southern Europe.

The researchers also reportthat there was much more wheat DNA found in the top half of the 8 cm soil sample than in the bottom half.

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DNA discovery: British people ate imported wheat 8,000 years ago

WORCESTER -- A superior court judge will decide if a former Fitchburg man serving 32-41 years for two separate child rapes will be granted a new trial to challenge the DNA results used as evidence in his first conviction in 2006.

Roy Dumas, 58, handcuffed and dressed in standard prison garb, appeared Thursday before Superior Court Judge Richard T. Tucker with his attorney, Edward Gauthier, to request a new trial.

Gauthier argued that during Dumas' first trial in 2006, the forensic expert who testified that Dumas' DNA matched that found on the victim did not actually test the DNA sample used to convict him.

Gauthier also said the victim never did positively identify Dumas as her attacker because a bag was put over her head before the sexual assault.

He also said Dumas presented an alibi defense that he was seen by at least three witnesses in another part of the state during the time of the assault.

"The nail in the coffin was the DNA evidence. It was the strongest part of the case," said Gauthier.

Dumas, said Gauthier after the hearing, was denied the right to cross examine the technician who tested the sample of his DNA during the first trial.

That, said Gauthier, is the basis of his request for a new trial.

But Assistant District Attorney Donna-Marie Haran said that when the DNA expert, who did not test the sample but reported the results, was cross-examined by Dumas' defense attorney, the opportunity to call the DNA tester as a witness was waived.

Haran cited case law that waived the right for the defense to call the DNA tester.

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Attorney: DNA untested in rape conviction