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Supercoil me!

Even living cells have their own tangled problems to solve. They involve knots that arise accidentally in DNA and that can comprise its functionality. A new study by SISSA (Scuola Internazionale Superiore di Studi Avanzati) brings a new twist to the problem and suggests that the DNA propensity to be supercoiled, just like telephone cords, can come to the rescue. These coils can keep DNA knots locked in place for long enough that they can be untied by specialised enzymes. The computational study, based on molecular dynamics simulations of bacterial DNA, has just been published in Nucleic Acids Research . A tangled problem Supercoiled, twisted, and even knotted! Far from the elegant and polished textbook images, DNA filaments in living cells is all crumpled and entangled and, to be functional, needs to be constantly unravelled, much like our telephone cords that with careless use accumulate annoying curls or supercoils. "Supercoils are, in fact, present in DNA too

Timing is key for bacteria surviving antibiotics

For bacteria facing a dose of antibiotics, timing might be the key to evading destruction. In a series of experiments, Princeton researchers found that cells that repaired DNA damaged by antibiotics before resuming growth had a much better chance of surviving treatment. When antibiotics hit a population of bacteria, often a small fraction of "persister" cells survive to pose a threat of recurrent infection. Unlike bacteria with genetic resistance to antibiotics, evidence suggests that persisters stay alive in part by stalling cellular processes targeted by the drugs. In a new study, Princeton researchers examined a class of antibiotics that target bacterial DNA. In bacterial populations, some cells repair damaged DNA before resuming growth, and others resume growth before making repairs. The researchers found that those that make repairs before resuming growth generally are the ones that survive as persisters. The research advances a long-term goal to make

Nanoparticles derived from tea leaves destroy lung cancer cells: Quantum dots have great potential

Nanoparticles derived from tea leaves inhibit the growth of lung cancer cells, destroying up to 80% of them, new research by a joint Swansea University and Indian team has shown. The team made the discovery while they were testing out a new method of producing a type of nanoparticle called quantum dots. These are tiny particles which measure less than 10 nanometres. A human hair is 40,000 nanometres thick. Although nanoparticles are already used in healthcare, quantum dots have only recently attracted researchers' attention. Already they are showing promise for use in different applications, from computers and solar cells to tumour imaging and treating cancer. Quantum dots can be made chemically, but this is complicated and expensive and has toxic side effects. The Swansea-led research team were therefore exploring a non-toxic plant-based alternative method of producing the dots, using tea leaf extract. Tea leaves contain a wide variety of compounds, including

Increased overweight in children of mothers who drank coffee while pregnant

A study published in the BMJ Open journal shows that even moderate coffee consumption during pregnancy, one to two cups per day, is related to a risk of overweight or obesity in school age children. It has not been clearly shown if caffeine is the direct cause of the overweight, but the relationship, alone, has caused researchers to encourage increased caution. "There may be good cause to increase the restriction of the recommended maximum of three cups of coffee per day. Caffeine is not a medicine that needs to be consumed," says Verena Sengpiel, Associate Professor in obstetrics and gynecology at Sahlgrenska Academy, Sweden, and specialist physician at the Department of Obstetrics and Gynecology at Sahlgrenska University Hospital. Researchers at Sahlgrenska Academy, in collaboration with the Norwegian Institute of Public Health, studied information on 50 943 pregnant women, in one of the world's largest health surveys of pregnant women, the Norwegian

HIV lies dormant in brain?

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The HIV virus, which causes AIDS, has long been known to target and disable cells of the immune system, which are responsible for fighting off invading microorganisms and for suppressing malignant cancers. More recently, researchers also learned HIV not only targets immune cells in the bloodstream but also in the brain and spinal cord and that HIV can lie dormant in a person’s body for many years. My mentor, Dr. Habibeh Khoshbouei , has been working on this problem and learned that one consequence of HIV in the brain is that age-related diseases develop much earlier . This includes neurological conditions such as Alzheimer’s and Parkinson’s disease , as well as an increased susceptibility to drug addiction . Our lab wanted to learn why. HIV effects persist despite treatment HIV, the virus that causes AIDS, is shown budding out of an immune cell, which the virus infects and uses to replicate. NIH, via Wi

Extreme stress in childhood is toxic to your DNA

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The real danger of separating children from parents is not the psychological stress – it’s the biological time bomb. The screaming and crying, the anguish and desolation is gut-wrenching. But the fallout pales in comparison to the less visible long-term effects that are more sinister and dangerous. Separating children from their parents, in a strange land, among strangers, causes the most extreme life stress a child can experience. And it causes profound and irreversible changes in how their DNA is packaged and which genes are turned on and off in the cells of the body, in organs like the pancreas, the lungs, heart and brain – leading to lifelong changes in its structure and function. I am the director of the Lieber Institute for Brain Development and the Maltz Research Laboratories at the Johns Hopkins University School of Medicine, where scientists study how genes and the environment shape the development of the human brain. Our studies and those of many other resea

How does your body ‘burn’ fat?

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Many of us may be considering “burning some fat” so we feel better in our bathing suits out on the beach or at the pool. What does that actually mean, though? The normal fat cell exists primarily to store energy. The body will expand the number of fat cells and the size of fat cells to accommodate excess energy from high-calorie foods. It will even go so far as to start depositing fat cells on our muscles, liver and other organs to create space to store all this extra energy from calorie-rich diets – especially when combined with a low activity lifestyle. Historically, fat storage worked well for humans. The energy was stored as small packages of molecules called fatty acids , which are released into the bloodstream for use as fuel by muscles and other organs when there was no food available, or when a predator was chasing us. Fat storage actually conferred a survival advantage in these situations. Those with a tendency to store fat were able to survive longer period