Study led by NUS researchers proves the existence of 3 overstretched DNA structures
Friday, March 1, 2013
A team of researchers led by Associate Professor Yan Jie from the Department of Physics at the National University of Singapore (NUS) Faculty of Science has identified three new distinct overstretched deoxyribonucleic acid (DNA) structures caused by mechanical stretching. This discovery provides a clear answer to a long-running debate among scientists over the nature of DNA overstretching.
Debate on Possible DNA Structural Transitions
Recent single-molecule studies revealed that mechanical stretching could induce transitions to elongated DNA structures. Three possible elongated DNA structures have been proposed, namely: a single-stranded DNA under tension, DNA bubbles consisting two parallel, separated single-stranded DNA under tension, and a new form of base-paired double-stranded DNA. The existence of the three transitions has been heavily discussed among scientists for some 17 years.
To fully understand the nature of DNA overstretching, the team led by Assoc Prof Yan, which comprises members from NUS, the University of Minnesota and the Massachusetts Institute of Technology, explored the possible structural transitions.
Three Distinct Transitions Revealed
In their recent study, the researchers systematically investigated the three possible transitions induced by mechanical stretching, with methods to control DNA construct, temperature, force and salt concentration. Their data successfully identified all the three proposed structures and fully characterised their respective thermo-mechanical properties. These findings were first published on the online version of the Proceedings of the National Academy of Sciences on 19 February 2013.
These findings complete the picture about the structures of DNA under tension, providing a conclusion to the 17-year-old debate.
An illustration of three distinct elongated DNA structures produced by mechanical stretching (Image credit: NUS)
Biological Implications and Potential Applications
As forces over a wide range are present in the DNA of cells, the researchers' findings provide new perspectives of possible force-dependent regulations of critical biological processes, such as DNA damage repair and gene transcriptions.
In addition, as many recently developed DNA devices are based on thermo-mechanical properties of various DNA structural motifs, these findings may also have potential applications in designing new DNA devices for the future.
The Next Step
To further their research, Assoc Prof Yan and his team will study the physiological functions of the three overstretched DNA structures, and investigate the presence of any new DNA structures under other mechanical constraints.
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National University of Singapore: http://www.nus.edu.sg/
Thanks to National University of Singapore for this article.
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Postmenopausal women who smoked are more likely to lose teeth due to periodontal diseasePublic release date: 1-Mar-2013 [ | E-mail | Share ]
Contact: Ellen Goldbaum goldbaum@buffalo.edu 716-645-4605 University at Buffalo
BUFFALO, N.Y. Postmenopausal women who have smoked are at much higher risk of losing their teeth than women who never smoked, according to a new study published and featured on the cover of the Journal of the American Dental Association by researchers at the University at Buffalo.
The study involved 1,106 women who participated in the Buffalo OsteoPerio Study, an offshoot of the Women's Health Initiative, (WHI), the largest clinical trial and observational study ever undertaken in the U.S., involving more than 162,000 women across the nation, including nearly 4,000 in Buffalo.
The UB study is the first to examine comprehensive smoking histories for participants that allowed the researchers to unravel some of the causes behind tooth loss in postmenopausal women who smoked.
The study, which appears in the journal's current issue is available at http://jada.ada.org/content/144/3/252.full.
Smoking has long been associated with tooth loss, but postmenopausal women, in particular, experience more tooth loss than their male counterparts.
"Regardless of having better oral health practices, such as brushing and flossing, and visiting the dentist more frequently, postmenopausal women in general tend to experience more tooth loss than men of the same age," says Xiaodan (pronounced Shee-ao-dan) Mai, a doctoral student in epidemiology in the UB Department of Social and Preventive Medicine in the School of Public Health and Health Professions. "We were interested in smoking as a variable that might be important."
While fewer adults lose their teeth now than in past decades, tooth loss is associated with poor health outcomes, including stroke, cancer, rheumatoid arthritis and diabetes.
In the UB study, heavy smokers -- defined as those who had at least 26 pack-years of smoking, or the equivalent of having smoked a pack a day for 26 years -- were nearly twice as likely to report having experienced tooth loss overall and more than six times as likely to have experienced tooth loss due to periodontal disease, compared to those who never smoked.
Participants provided information to researchers using a detailed questionnaire covering smoking history. Each participant also underwent a comprehensive oral examination and reported to the dental examiners reasons for each tooth lost. In some cases, the patient's dental records also were reviewed.
"We found that heavy smokers had significantly higher odds of experiencing tooth loss due to periodontal disease than those who never smoked," explains Mai. "We also found that the more women smoked, the more likely they experienced tooth loss as a result of periodontal disease."
On the other hand, they found that smoking was a less important factor in tooth loss due to caries. That's an important distinction, says Mai.
"Periodontal disease is a chronic, inflammatory condition that may be related to the development of cancer," she explains.
The paper notes that cigarette smoke may accelerate periodontal disease and that other studies suggest that chemicals found in smoke may favor plaque-forming bacteria that could reduce the ability of saliva to be antioxidative. Nicotine also has been shown to reduce bone density and bone mineral factors while estrogen hormones have been found to be lower among women who smoke.
Mai is now interested in pursuing research that could determine whether smokers with periodontal disease are at even greater risk for certain cancers than smokers without periodontal disease.
"Tooth loss due to periodontal disease is a prevalent condition among postmenopausal women that severely impacts their dietary intake, aesthetics, and overall quality of life," says Mai. "Women now have yet another, very tangible reason for quitting smoking."
###
Co-authors with Mai are: Jean Wactawaski-Wende, PhD, principal investigator on the WHI, professor and associate chair of the UB Department of Social and Preventive Medicine, professor of gynecology-obstetrics, and UB's vice provost for strategic initiatives; Kathleen M. Hovey, data analyst, Michael J. LaMonte, PhD, assistant professor and Chaoru Chen, PhD, formerly a postdoctoral scholar, all in the UB Department of Social and Preventive Medicine. Mine Tezal, DDS, PhD, assistant professor and Robert J. Genco, DDS, PhD, Distinguished Professor of Oral Biology and Microbiology in the Department of Oral Biology, both in the UB School of Dental Medicine also are co-authors.
The research was funded by the National Institute of Dental and Craniofacial Research and the National Heart Lung and Blood Institute, both of the National Institutes of Health, and the US Army Medical Research and Materiel Command.
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AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
Postmenopausal women who smoked are more likely to lose teeth due to periodontal diseasePublic release date: 1-Mar-2013 [ | E-mail | Share ]
Contact: Ellen Goldbaum goldbaum@buffalo.edu 716-645-4605 University at Buffalo
BUFFALO, N.Y. Postmenopausal women who have smoked are at much higher risk of losing their teeth than women who never smoked, according to a new study published and featured on the cover of the Journal of the American Dental Association by researchers at the University at Buffalo.
The study involved 1,106 women who participated in the Buffalo OsteoPerio Study, an offshoot of the Women's Health Initiative, (WHI), the largest clinical trial and observational study ever undertaken in the U.S., involving more than 162,000 women across the nation, including nearly 4,000 in Buffalo.
The UB study is the first to examine comprehensive smoking histories for participants that allowed the researchers to unravel some of the causes behind tooth loss in postmenopausal women who smoked.
The study, which appears in the journal's current issue is available at http://jada.ada.org/content/144/3/252.full.
Smoking has long been associated with tooth loss, but postmenopausal women, in particular, experience more tooth loss than their male counterparts.
"Regardless of having better oral health practices, such as brushing and flossing, and visiting the dentist more frequently, postmenopausal women in general tend to experience more tooth loss than men of the same age," says Xiaodan (pronounced Shee-ao-dan) Mai, a doctoral student in epidemiology in the UB Department of Social and Preventive Medicine in the School of Public Health and Health Professions. "We were interested in smoking as a variable that might be important."
While fewer adults lose their teeth now than in past decades, tooth loss is associated with poor health outcomes, including stroke, cancer, rheumatoid arthritis and diabetes.
In the UB study, heavy smokers -- defined as those who had at least 26 pack-years of smoking, or the equivalent of having smoked a pack a day for 26 years -- were nearly twice as likely to report having experienced tooth loss overall and more than six times as likely to have experienced tooth loss due to periodontal disease, compared to those who never smoked.
Participants provided information to researchers using a detailed questionnaire covering smoking history. Each participant also underwent a comprehensive oral examination and reported to the dental examiners reasons for each tooth lost. In some cases, the patient's dental records also were reviewed.
"We found that heavy smokers had significantly higher odds of experiencing tooth loss due to periodontal disease than those who never smoked," explains Mai. "We also found that the more women smoked, the more likely they experienced tooth loss as a result of periodontal disease."
On the other hand, they found that smoking was a less important factor in tooth loss due to caries. That's an important distinction, says Mai.
"Periodontal disease is a chronic, inflammatory condition that may be related to the development of cancer," she explains.
The paper notes that cigarette smoke may accelerate periodontal disease and that other studies suggest that chemicals found in smoke may favor plaque-forming bacteria that could reduce the ability of saliva to be antioxidative. Nicotine also has been shown to reduce bone density and bone mineral factors while estrogen hormones have been found to be lower among women who smoke.
Mai is now interested in pursuing research that could determine whether smokers with periodontal disease are at even greater risk for certain cancers than smokers without periodontal disease.
"Tooth loss due to periodontal disease is a prevalent condition among postmenopausal women that severely impacts their dietary intake, aesthetics, and overall quality of life," says Mai. "Women now have yet another, very tangible reason for quitting smoking."
###
Co-authors with Mai are: Jean Wactawaski-Wende, PhD, principal investigator on the WHI, professor and associate chair of the UB Department of Social and Preventive Medicine, professor of gynecology-obstetrics, and UB's vice provost for strategic initiatives; Kathleen M. Hovey, data analyst, Michael J. LaMonte, PhD, assistant professor and Chaoru Chen, PhD, formerly a postdoctoral scholar, all in the UB Department of Social and Preventive Medicine. Mine Tezal, DDS, PhD, assistant professor and Robert J. Genco, DDS, PhD, Distinguished Professor of Oral Biology and Microbiology in the Department of Oral Biology, both in the UB School of Dental Medicine also are co-authors.
The research was funded by the National Institute of Dental and Craniofacial Research and the National Heart Lung and Blood Institute, both of the National Institutes of Health, and the US Army Medical Research and Materiel Command.
[ | E-mail | Share ]
?
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
DENVER (AP) -- March is a make-or-break month for relieving drought conditions in Colorado.
State climatologist Nolan Doesken says a series of snow storms or one monster blizzard, like the one in 2003, would go a long way to improve conditions along the Front Range and Eastern Plains.
The month is traditionally a wet one. But last year the state dried out during an extremely dry and warm March, which also marked the start of a deadly wildfire season.
April and May often bring rain and snow too. Doesken says March precipitation is key because the normally cooler weather helps moisture penetrate the ground and slows evaporation.
Doesken said this week's series of storms benefited any areas that got at least 7 inches of snow, the equivalent of about a ? inch of water.
A 24-year-old Pennsylvania woman abandoned her 8-month-old daughter in the woods with the hopes of getting ?a fresh start,? according to police.
Jennifer Cutruzzula was spotted by a neighbor walking into the woods with her child, only to emerge alone. The neighbor called police and went into the woods and found the baby girl on a muddy hillside next to a bottle of milk.
?She walked into this area with the intention of abandoning the child,? said Alleghany County District Attorney Stephen Zappala.
Cutruzzula told police she left her child because she wanted ?a fresh start,? according to a criminal complaint.
Authorities say the infant is fine after being treated and released from a local hospital. The baby is currently in the custody of Child and Youth Services, according to WPXI-TV Pittsburgh.
Cutruzzula is charged with endangering the welfare of children and recklessly endangering. She is being held on $50,000 bail.
Zappala said the Pittsburgh-area woman will undergo a mental evaluation.
?I have never see anything like this. I don?t know how anyone could leave a child in the woods and walk away,? said Zappala.
This is far from the first attempt at incorporating a bottle opener into an iPhone case. But the Fortress 2 from XGearlive is hands down the only design you should consider. Instead of a clunky slide-out mechanism, or an unsightly bulge on the back, it neatly integrates a subtle opener onto the edge of its bumper case form factor. More »
VIENNA (Reuters) - Iran's foreign minister said he sees a chance to improve ties with the United States, despite a longrunning standoff with major powers over his country's disputed nuclear program.
Austrian newspaper Wiener Zeitung also quoted Ali Akbar Salehi as saying that Iran was reducing stockpiles of its most sensitive nuclear material, which the West fears could be used to make bombs. Iran denies seeking a nuclear weapons capability.
Asked whether U.S. President Barack Obama's re-election could lead to a better climate between two nations that severed diplomatic ties more than three decades ago, Salehi said: "This environment is just being created and shaped. I think both sides want to use this opportunity."
Tehran struck an upbeat tone after talks this week with world powers ended with an agreement to meet again, but Western officials said it had yet to take concrete steps to ease their fears about its nuclear ambitions.
In the Wiener Zeitung interview published on Friday, Salehi referred to the latest talks in Kazakhstan as a "milestone" and likened the situation to ice that was beginning to melt.
He gave no details about the negotiations, but said Iran was increasing efforts to reduce stockpiles of uranium enriched to 20 percent purity, a bone of contention with the West.
Salehi said nearly 100 kg (220 lb) of the roughly 250 kg of uranium Iran has enriched to 20 percent purity so far had been processed into fuel plates for a research reactor in Tehran.
"So far we have produced two of these plates per month. In future we want to produce three, four or perhaps even more fuel plates every month. This is how we want to reduce the supply of 20 percent enriched uranium in the medium term," he said.
Iran says it has a sovereign right to enrich uranium for peaceful purposes and that it wants to fuel nuclear power plants so that it can export more oil.
But 20 percent purity is far higher than that needed for nuclear power, and rings alarm bells abroad because it is only a short technical step away from weapons-grade uranium. Iran says it produces higher-grade uranium to fuel the research reactor.
A report by the U.N. nuclear watchdog last month said Iran had increased its stockpile of 20 percent enriched uranium to 167 kg.
Diplomats say conversion of more of Iran's higher-grade enriched uranium into reactor fuel could buy time for negotiations between Washington and Tehran on its nuclear program.
U.S. Secretary of State John Kerry has called the talks in Kazakhstan "useful" and said that a serious engagement by Iran could lead to a comprehensive deal in a decade-old dispute that has threatened to trigger a new Middle East war.
(Reporting by Michael Shields; Editing by Alistair Lyon)
Common wisdom would suggest that executives talk up their existing device lines to keep customers buying until the next generation is ready. Leave it to Google CFO Patrick Pichette to think outside the box, if not necessarily for the better. He told guests at the Morgan Stanley Technology Conference that the currentroster, while good, doesn't "'wow' by Google standards" -- it reflects the 18-month device pipeline that fell in Google's lap when it acquired Motorola last year. As such, we won't see the full fruits of collaboration until Google has owned Motorola for long enough to put its own spin on products. While the remarks stoke the fires of anticipation for any future flagships, they may have unintentionally produced an Osborne Effect: however advanced Motorola's phones will be in the near term, customers may still have the nagging suspicion that something better is just around the corner.
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Public release date: 1-Mar-2013
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