Links for Keyword: Epigenetics

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Exploration forges differences in identical twins

By Puneet Kollipara Identical twin mice sharing the same mazelike environment develop distinct personalities based on how much they explore their surroundings, researchers report in the May 10 Science. After death, those differences were reflected in the animals’ brains. The study “highlights something for which we had some intuition before, but actually quantifies it,” says Fred Gage, a neuroscientist at the Salk Institute for Biological Studies in La Jolla, Calif. Some character and biological differences between identical twins may originate as early as pregnancy. But twins become more and more different as life goes on, even when they grow up together. Scientists have recognized that having distinct experiences within the same environment might boost such personality differences, but that’s difficult to test in humans. Studying it in animals has multiple benefits. “You can keep the genes constant and also keep the environment constant,” says Gerd Kempermann of the Center for Regenerative Therapies Dresden in Germany. “It’s much more controlled than in a human situation.” Researchers led by Kempermann put 40 genetically identical female mice in an elaborate cage and observed their behavior. The cage had multiple levels linked together by tubes and contained toys and other features that the animals could explore. The researchers equipped each mouse with a microchip that tracked its location, using the animals’ movements as a measure of exploratory behavior. Initially, the mice differed only slightly in their tendency to roam. As they grew older, all tended to explore more often, but the differences among the mice grew more pronounced. © Society for Science & the Public 2000 - 2013

Related chapters from BP6e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 18145 - Posted: 05.11.2013

From Great Grandma to You

By Tina Hesman Saey Like many women with parents of the Mad Men generation, Susan Murphy grew up in a household full of cigarette smoke. Both dad and mom smoked heavily, even while Murphy was still in her mother’s womb. “That explains a lot,” Murphy quips, poking fun at herself. But Murphy isn’t worried about her own health. She’s fine. Her children aren’t, though. One boy died of cancer as a toddler. Another has autism. And her daughter has attention deficit disorder. Murphy knows the scientific evidence isn’t in yet, but she still can’t help wondering whether their fates might have been affected by her exposure to tobacco smoke before she was born. Murphy, a researcher at Duke University, studies links between a mother’s diet and chemical exposures during pregnancy with the child’s later health. She and others have established that the womb is the antithesis of Las Vegas; what happens there not only doesn’t stay there, it can influence a child’s health for life. Now, animal studies and a smattering of human data suggest such prenatal effects could reach farther down the family tree: The vices, virtues, inadvertent actions and accidental exposures of a pregnant mother may pose health consequences for her grandchildren and great-grandchildren, and perhaps even their offspring. Scientists have long known that radiation or certain chemicals can cause typos in a developing fetus’s genome — his or her genetic instruction book. Such mutations can get passed along to future generations in the DNA of sperm or egg cells. While exposure to sex hormones or a high-fat diet in the womb doesn’t directly change or damage DNA, those sorts of exposures can induce scribblings in the genome’s margins that can also be passed down. © Society for Science & the Public 2000 - 2013

Study Finds How Genes That Cause Illness Work

By GINA KOLATA It has been one of the toughest problems in genetics. How do investigators figure out not just what genes are involved in causing a disease, but what turns those genes on or off? What makes one person with the genes get the disease and another not? Now, in a pathbreaking paper, researchers at the Johns Hopkins University School of Medicine and the Karolinska Institute in Sweden report a way to evaluate one gene-regulation system: chemical tags that tell genes to be active or not. Their test case was of patients with rheumatoid arthritis, a crippling autoimmune disease that affects 1.5 million Americans. It was an investigation of epigenetics, a popular area of molecular biology that looks for modifications of genes that can help determine disease risk. “This is one of the first studies that looks for an epigenetic disease association in a really rigorous fashion,” said Dr. Bradley Bernstein of Harvard, who was not associated with the study. Kun Zhang of the University of California, San Diego, made a similar observation. “I am quite impressed with their level of rigor and sophistication,” he said. In previous genomic studies, researchers with papers in leading journals “have made major claims, but after a few months or a year they were retracted,” he said. Those investigators, Dr. Zhang added, “did not treat their data very carefully.” In the new study, researchers compared 354 newly diagnosed rheumatoid arthritis patients and 337 healthy people who served as controls. The goal was to review both groups’ white blood cells, examining their DNA for chemical tags — methyl groups — that could attach themselves to genes and turn them on or off. © 2013 The New York Times Company

Epigenetics posited as important for evolutionary success

Sujata Gupta Two things are thought to be crucial for evolutionary adaptation: genetic diversity and long periods of time, in which advantageous mutations accumulate. So how do invasive species, which often lack genetic diversity, succeed so quickly? Some ecologists are beginning to think that environmental, or ‘epigenetic’, factors might be modifying genes while leaving the genome intact. “There are a lot of different ways for invasive species to do well in novel environments and I think epigenetics is one of those ways,” says Christina Richards, an evolutionary ecologist at the University of South Florida in Tampa. Although biomedical researchers have been investigating the links between epigenetics and human health for some time, evolutionary biologists are just beginning to take up the subject. Richards, who helped to organize a special symposium on ecological epigenetics at a meeting of the Society for Integrative and Comparative Biology (SICB) in San Francisco this month, says that the field has the potential to revolutionize the study of evolutionary biology. The nascent field of ecological epigenetics has plenty of challenges standing in its way. The genomes of most wild animals and plants have not been sequenced so ecologists can’t pinpoint which genes have been modified. And, because they tend to work outside of controlled laboratory conditions, researchers have trouble linking those gene modifications to behavioural changes. © 2013 Nature Publishing Group

Related chapters from BP6e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 17674 - Posted: 01.12.2013

Suicidal Threads

By Laura Sanders When sociologist Mike Tomlinson began combing through the health records of people in Northern Ireland, he wasn’t interested in suicide. He was on the hunt for links between poverty and international conflict. But he came across a startling trend. From 1998 to 2008, the rate at which men in their mid-30s to mid-50s were committing suicide rose alarmingly fast, more quickly than the rate for the rest of Northern Ireland’s population. At first, that spike made no sense. A peace agreement reached in 1998 transformed Northern Ireland into a prosperous and tranquil place. Economic indicators had been surprisingly good. Suicide rates in neighboring countries were all gently falling. Nothing seemed to explain why so many of these men were killing themselves. But Tomlinson found a hint in the men’s pasts. They had all grown up in the late 1960s and the 1970s, during some of the worst violence Northern Ireland had ever experienced. Called the Troubles, this warlike period brought religious and political fighting that pitted neighbor against neighbor. Children of the Troubles lived with terrorism, house-to-house searches, curfews and bomb explosions. Trauma early in life had rendered men more vulnerable to taking their own lives later, Tomlinson proposed in July in International Sociology. “If you were younger then, you carry that through,” says Tomlinson, of Queen’s University Belfast. This idea, that something that happened long ago could have such a profound effect today, seemed to resonate with others. When he described his idea to a suicide prevention group in Northern Ireland, “they just lit on it, and said it speaks so much to what they were seeing.” © Society for Science & the Public 2000 - 2012

Related chapters from BP6e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 11: Emotions, Aggression, and Stress
Link ID: 17391 - Posted: 10.20.2012

Study shows where identical twins part ways

By Tina Hesman Saey Identical twins aren’t perfect carbon copies of each other even at birth. Twins emerge from the womb carrying different chemical marks on their DNA that influence the activity of individual genes, a new study shows. Known as epigenetic markers, these alterations don’t change the underlying genetic information. But by regulating the activity of certain genes, they can profoundly influence how the DNA blueprint is used to create and operate a living organism. Past research has shown that identical twins bear some differences in epigenetic markers. But those differences were thought to arise after birth, as twins have different life experiences and encounter different environments. The new study — the first to measure epigenetic profiles in newborns — suggests that subtle differences in conditions within the womb can leave marks on fetal DNA that may have long-term consequences for adult health. These differing chemical tags may help explain why identical twins look slightly different, have their own personalities and may have different susceptibility to diseases. Jeffrey Craig, a molecular and cell biologist at Murdoch Childrens Research Institute in Parkville, Australia, and his colleagues report the findings online July 15 in Genome Biology. Identical twins are on average more epigenetically similar than fraternal twins, the researchers found. The similarity was probably not due to sharing a womb, but could be attributed partially to genetics and partially to chance, they suggest. © Society for Science & the Public 2000 - 2012

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