Scientists discover how epigenetic information could be inherited

New research reveals a potential way for how parents’ experiences could be passed to their offspring’s genes. The research was published in the journal Science.

Epigenetics is a system that turns our genes on and off. The process works by chemical tags, known as epigenetic marks, attaching to DNA and telling a cell to either use or ignore a particular gene.

The most common epigenetic mark is a methyl group. When these groups fasten to DNA through a process called methylation they block the attachment of proteins which normally turn the genes on. As a result, the gene is turned off.

Scientists have witnessed epigenetic inheritance, the observation that offspring may inherit altered traits due to their parents’ past experiences. For example, historical incidences of famine have resulted in health effects on the children and grandchildren of individuals who had restricted diets, possibly because of inheritance of altered epigenetic marks caused by a restricted diet.

However, it is thought that between each generation the epigenetic marks are erased in cells called primordial gene cells (PGC), the precursors to sperm and eggs. This ‘reprogramming’ allows all genes to be read afresh for each new person – leaving scientists to question how epigenetic inheritance could occur.

The new Cambridge study initially discovered how the DNA methylation marks are erased in PGCs, a question that has been under intense investigation over the past 10 years. The methylation marks are converted to hydroxymethylation which is then progressively diluted out as the cells divide. This process turns out to be remarkably efficient and seems to reset the genes for each new generation. Understanding the mechanism of epigenetic resetting could be exploited to deal with adult diseases linked with an accumulation of aberrant epigenetic marks, such as cancers, or in ‘rejuvenating’ aged cells.

However, the researchers, who were funded by the Wellcome Trust, also found that some rare methylation can ‘escape’ the reprogramming process and can thus be passed on to offspring – revealing how epigenetic inheritance could occur. This is important because aberrant methylation could accumulate at genes during a lifetime in response to environmental factors, such as chemical exposure or nutrition, and can cause abnormal use of genes, leading to disease. If these marks are then inherited by offspring, their genes could also be affected.

Frontiers publishes systematic review on the effects of yoga on major psychiatric disorders

Yoga has positive effects on mild depression and sleep complaints, even in the absence of drug treatments, and improves symptoms associated with schizophrenia and ADHD in patients on medication, according to a systematic review of the exercise on major clinical psychiatric disorders.

Published in the open-access journal, Frontiers in Psychiatry, on January 25th, 2013, the review of more than one hundred studies focusing on 16 high-quality controlled studies looked at the effects of yoga on depression, schizophrenia, ADHD, sleep complaints, eating disorders and cognition problems.

(Image: Corbis)

This Music Video Was Filmed Inside an MRI Machine

Musicians sometimes describe their music as an intimate look inside their minds. But an artist named Sivu has taken that notion literally with the music video for his song Better Man Than He that was actually filmed inside an MRI machine.

Lightning May Trigger Migraine Headaches

Migraine sufferers know that a variety of influences—everything from stress to hunger to a shift in the weather—can trigger a dreaded headache. A new study published in the journal Cephalalgia, though, suggests that another migraine trigger could be an unexpected atmospheric condition—a bolt of lightning.

As part of the study, Geoffrey Martin of the University of Cincinnati and colleagues from elsewhere asked 90 chronic migraine sufferers in Ohio and Missouri to keep detailed daily diaries documenting when they experienced headaches for three to six months. Afterward, they looked back over this period and analyzed how well the occurrence of headaches correlated with lightning strikes within 25 miles of the participants’ houses, along with other weather factors such as temperature and barometric pressure.

Their analysis found that there was a 28 precent increased chance of a migraine and a 31 precent chance of a non-migraine (i.e. less severe) headache on days when lightning struck nearby. Since lightning usually occurs during thunderstorms, which bring a host of other weather events—notable changes in barometric pressure—they used mathematical models to parse the related factors and found that even in the absence of other thunderstorm-related elements, lightning alone caused a 19 percent increased chance of headaches.

Despite these results, it’s probably a bit premature to argue that lightning is a definitive trigger of migraines. For one, a number of previous studies have explored the links between weather and migraine headaches, and the results have been unclear. Some have suggested that high pressure increases the risk of headaches, while others have indicated that low pressure increases the risk as well. Other previous studies, in fact, have failed to find a link between migraines and lightening, in particular.

Deep brain stimulation improves autistic boy’s symptoms

Electrodes implanted deep in the brain of a boy with severe autism have enabled him to live a more normal life. The treatment reduced his destructive behavior and allowed the formerly nonverbal boy to speak a few words, scientists report online January 21 in Frontiers in Human Neuroscience.

The results are the first to use brain stimulation to alleviate symptoms of autism. Scientists caution that interpreting the results broadly is impossible without larger, systematic studies, but even so neurosurgeon Ali Rezai of the Ohio State University Wexner Medical Center in Columbus calls the boys’ gains “intriguing and promising.”

The boy in the study, who was 13 at the time of his experimental surgery, suffered from severe autism symptoms: He couldn’t talk or make eye contact, woke up screaming repeatedly during the night, and habitually injured himself so badly that his parents restrained him almost constantly to protect him. Multiple rounds of psychiatric drugs failed to stave off his worsening symptoms.

In an effort to help him, doctors led by Volker Sturm of the University Hospital of Cologne in Germany implanted electrodes into the boy’s brain. Through trial and error, the doctors realized that stimulating a part of the amygdala, a brain structure important for emotions and memory, improved the boy’s symptoms. Stimulating other brain areas had no effect or worsened his symptoms.

After eight weeks of continuous electrical stimulation, the boy shifted on a clinical scale that measures irritability from “severely ill” to “moderately ill.” The boy also improved on a scale that measures autism symptoms. He began to make eye contact and was better able to control his behavior.

Prenatal inflammation linked to autism risk

Maternal inflammation during early pregnancy may be related to an increased risk of autism in children, according to new findings supported by the National Institute of Environmental Health Sciences (NIEHS), part of the National Institutes of Health.Researchers found this in children of mothers with elevated C-reactive protein (CRP), a well-established marker of systemic inflammation.

The risk of autism among children in the study was increased by 43 percent among mothers with CRP levels in the top 20th percentile, and by 80 percent for maternal CRP in the top 10th percentile. The findings appear in the journal Molecular Psychiatry and add to mounting evidence that an overactive immune response can alter the development of the central nervous system in the fetus.

“Elevated CRP is a signal that the body is undergoing a response to inflammation from, for example, a viral or bacterial infection,” said lead scientist on the study, Alan Brown, M.D., professor of clinical psychiatry and epidemiology at Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute, and Mailman School of Public Health. “The higher the level of CRP in the mother, the greater the risk of autism in the child.”

“Connection error” in the brains of anorexics

When people see pictures of bodies, a whole range of brain regions are active. This network is altered in women with anorexia nervosa. In a functional magnetic resonance imaging study, two regions that are important for the processing of body images were functionally more weakly connected in anorexic women than in healthy women. The stronger this “connection error” was, the more overweight the respondents considered themselves. “These alterations in the brain could explain why women with anorexia perceive themselves as fatter, even though they are objectively underweight” says Prof. Dr. Boris Suchan of the Institute of Cognitive Neuroscience at the Ruhr-Universität. Together with Prof. Dr. Dietrich Grönemeyer (University of Witten-Herdecke), Prof. Dr. Silja Vocks (University of Osnabrück) and other colleagues, the Bochum researchers report in the journal Behavioural Brain Research.

Anorexics misperceive their body shape

The researchers tested ten anorexic and fifteen healthy women of similar age. To start with, all the women judged on the computer which of several different silhouettes corresponded best to their own body shape. Ten control subjects who did not participate in the MRI scan answered the same question by matching a photo of the test subject to the right silhouette. Both healthy and anorexic women estimated their body shape differently than outsiders: healthy subjects rated themselves as thinner than the control subjects. Anorexic women on the other hand perceived themselves to be fatter than the control subjects did.

Brain areas for body perception examined with MRI

In MRI scanners, the researchers then recorded the brain activity of the 25 participants while they observed photos of bodies. Above all, they analysed the activity in the “fusiform body area” (FBA) and the “extrastriate body area” (EBA), because previous studies showed that these brain regions are critical for the perception of bodies. To this end, the neuroscientists from Bochum calculated the so-called effective connectivity between the FBA and EBA in both hemispheres. This is a measure of how much the activity in several brain areas is temporally correlated. A high degree of correlation is indicative of a strong connection.

Brains of anorexics structurally and functionally altered

The connection between the FBA and EBA was weaker in women with anorexia nervosa than in healthy women. In addition, the researchers found a negative correlation between the EBA-FBA connection in the left hemisphere and the misjudgement of body weight: the weaker the effective connectivity between the EBA and FBA was, the fatter the subjects with anorexia falsely estimated themselves to be. “In a previous study we found that there are structural changes in the brains of patients with anorexia”, says Boris Suchan. They have a lower density of nerve cells in the EBA. “The new data shows that the network for body processing is also functionally altered.” The EBA, which has a lower cell density in anorexics, is also the area that stood out in the connection analysis: it receives reduced input from the FBA. “These changes could provide a mechanism for the development of anorexia”, says Suchan.

Genetic landscape of common brain tumors holds key to personalized treatment

Nearly the entire genetic landscape of the most common form of brain tumor can be explained by abnormalities in just five genes, an international team of researchers led by Yale School of Medicine scientists report online in the Jan. 24 edition of the journal Science.  Knowledge of the genomic profile of the tumors and their location in the brain make it possible for the first time to develop personalized medical therapies for meningiomas, which currently are only managed surgically.

Meningioma tumors affect about 170,000 patients in the United States. They are usually benign but can turn malignant in about 10 percent of cases. Even non-cancerous tumors can require surgery if they affect the surrounding brain tissue and disrupt neurological functions. 

Approximately half of the tumors have already been linked to a mutation or deletion of a gene called neurofibromin 2, or NF2. The origins of the rest of the meningiomas had remained a mystery.

The Yale team conducted genomic analyses of 300 meningiomas and found four new genetic suspects, each of which yields clues to the origins and treatment of the condition. Tumors mutated with each of these genes tend to be located in different areas of the brain, which can indicate how likely they are to become malignant.

“Combining knowledge of these mutations with the location of tumor growth has direct clinical relevance and opens the door for personalized therapies,” said Dr. Murat Gunel, the Nixdorff-German Professor of Neurosurgery, professor of genetics and of neurobiology, and senior author of the study. Gunel is also a member of Yale Cancer Center’s Genetics and Genomics Research Program.

Chance finding reveals new control on blood vessels in developing brain

Zhen Huang freely admits he was not interested in blood vessels four years ago when he was studying brain development in a fetal mouse.

Instead, he wanted to see how changing a particular gene in brain cells called glia would affect the growth of neurons.

The result was hemorrhage, caused by deteriorating veins and arteries, and it begged for explanation.

"It was a surprising finding," says Huang, an assistant professor of neuroscience and neurology at the University of Wisconsin-Madison. "I was mainly interested in the neurological aspect, how the brain develops and wires itself to prepare for all the wonderful things it does."

But chance favors the prepared mind, as Louis Pasteur said, and Huang knew he needed to follow up on the suggestion that glia, normally considered “helpers” for the neurons, would affect the growth of blood vessels. For one thing, blood flow is a big deal in the brain, says Huang, whose collaborators included Shang Ma, in the graduate program in cellular and molecular biology at UW-Madison. “We know the brain is very energy-intensive. Per unit of volume, it consumes 10 times as much oxygen as the rest of the body.”

Although it makes intuitive sense that blood vessel development should be guided by neuronal development in some fashion, Huang spent years making sure he wasn’t being mislead by his experiment. Now, he’s satisfied himself, and his scientific reviewers, and the journal PLOS Biology has just published his study.