Researchers have shown in mice how immune cells in the brain target and remove unused connections between brain cells during normal development. This research, supported by the National Institutes of Health, sheds light on how brain activity influences brain development, and highlights the newly found importance of the immune system in how the brain is wired, as well as how the brain forms new connections throughout life in response to change.

Disease-fighting cells in the brain, known as microglia, can prune the billions of tiny connections (or synapses) between neurons, the brain cells that transmit information through electric and chemical signals. This new research demonstrates that microglia respond to neuronal activity to select synapses to prune, and shows how this pruning relies on an immune response pathway - the complement system - to eliminate synapses in the way that bacterial cells or other pathogenic debris are eliminated. The study was led by Beth Stevens, Ph.D., assistant professor of neurology at Boston Children's Hospital and Harvard Medical School.

The brain is created with many more synapses than it retains into adulthood. As the brain develops, it goes through dynamic changes to refine its circuitry, trimming away the synaptic connections that do not have a lot of activity, and preserving the stronger, more active synapses. This period, known as synaptic pruning, is a key part of normal brain development.

A moon of Saturn that looks like a cosmic wet sponge is in fact covered in ices, both of water and carbon dioxide, images from a NASA spacecraft show. Hyperion, with an irregular potato-like shape and honeycomb surface, is the subject of a new analysis of images taken by NASA's Cassini spacecraft in September 2005, ScienceNews.org reported Wednesday.

Hydrocarbons and iron-containing compounds mixed in with the ice give the moon a reddish appearance, researchers said. Writing in the planetary science journal Icarus, scientists say Hyperion shows similarities to some comets, suggesting the possibility the moon formed elsewhere before being captured by Saturn.

Scientists on Wednesday reported that they have for the first time taken skin cells from heart attacks patients and turned them into healthy heart tissue that could hopefully be used to one day repair damaged heart muscle.

The healthy, beating heart tissue was grown successfully in the lab from human-induced pluripotent stem cells (hiPSCs), and while scientists said they were not safe enough to put back into human patients, they appeared to work well with other cells when implanted into rats. HiPSCs are a recently discovered source far less controversial than use of embryonic stem cells. And, because the transplanted hiPSCs come from the individual, it could resolve the problems seen with tissue and organ rejection.

While the technique has shown promise in rats, the scientists say there are numerous obstacles to overcome and it could take up to ten years or longer before clinical trials could be available for humans. Even so, it is a significant advance in the quest for replacement cell therapy for heart failure patients.

"More people are surviving following a heart attack than ever before and therefore the number of people living with a damaged heart and heart failure is increasing," Nicholas Mills, a consultant cardiologist at Edinburgh University, told The Guardian. "Unfortunately, the body has only very limited capacity to repair the heart following a heart attack. There is therefore an urgent need to develop effective and safe treatments to regenerate the heart."

Recent research has shown that hiPSCs could be derived from young and healthy people and are capable of transforming into heart cells. However, researchers have not been able to obtain those cells from elderly and diseased patients. And until now, researchers have not been able to show that heart cells created from hiPSCs could integrate with existing heart tissue.

"What is new and exciting about our research is that we have shown that it's possible to take skin cells from an elderly patient with advanced heart failure and end up with his own beating cells in a laboratory dish that are healthy and young - the equivalent to the stage of his heart cells when he was just born," said lead researcher Professor Lior Gepstein, of Sohnis Research Laboratory for Cardiac Electrophysiology and Regenerative Medicine, Technion-Israel Institute of Technology and Rambam Medical Center in Haifa, Israel.

For decades, scientists believed that a spine with multiple segments was an exclusive feature of land-dwelling animals. But the discovery of the same anatomical feature in a 345-million-year-old eel suggests that this complex anatomy arose separately from - and perhaps before - the first species to walk on land.

Tarrasius problematicus was an eel-like fish that lived in shallow bodies of water in what is now Scotland, in the Carboniferous period between 359 million and 318 million years ago. Like many fish, Tarrasius was thought to have a vertebral column divided simply into body and tail segments. But in a new description of Tarrasius published in Proceedings of the Royal Society B, Lauren Sallan describes a five-segment column much more similar to the spinal anatomy of land-dwelling animals called tetrapods, including humans.

The surprising find argues against a common assumption paleontologists use to determine from fossils whether an ancient species lived on land or in water.

"It's the last trait to fall," said Sallan, a graduate student in the Program in Integrative Biology at the University of Chicago Biological Sciences. "First, limbs were thought to show that a species was on land and walking, and now the vertebral morphology doesn't mean that they're on land either. So a lot of the things we associate with tetrapods actually arose first in fishes, and this is another example of that."

Street lighting is changing bug communities and that is affecting everything from the songs birds sing to the makeup of people.

A new study found that scavenger and predator insects both collect near the lights. It also shows for the first time that their composition is affected by the lighting. The study is published in the latest Biology Letters.

In fact, streetlights and other forms of artificial lighting may affect all ecosystem members, from bugs to humans.

"The range of effects of light pollution are really very diverse," lead author Thomas Davies told Discovery News.

"They can affect reproductive successes in sea turtles, the timings of bird songs and even the physiology of humans."

He and his colleagues believe that "we are facing an insect biodiversity crisis," which merits our attention because "insects provide crucial services to humans, such as pollination and decomposition to organic matter."

Davies is a postdoctoral research fellow at the University of Exeter's Environment and Sustainability Institute. He and colleagues Jonathan Bennie and Kevin Gaston deployed several insect traps on grassy vegetation under and between streetlights in Helston, Cornwall, UK.

The traps were left in place for three days and nights and analyzed 30 minutes prior to sunrise and sunset.The amount of vegetation in an area was taken into account.

Over the past decade, research in the field of epigenetics has revealed that chemically modified bases are abundant components of the human genome and has forced us to abandon the notion we've had since high school genetics that DNA consists of only four bases.

Now, researchers at Weill Cornell Medical College have made a discovery that once again forces us to rewrite our textbooks. This time, however, the findings pertain to RNA, which like DNA carries information about our genes and how they are expressed. The researchers have identified a novel base modification in RNA which they say will revolutionize our understanding of gene expression.

Their report, published May 17 in the journal Cell, shows that messenger RNA (mRNA), long thought to be a simple blueprint for protein production, is often chemically modified by addition of a methyl group to one of its bases, adenine. Although mRNA was thought to contain only four nucleobases, their discovery shows that a fifth base, N6-methyladenosine (m6A), pervades the transcriptome. The researchers found that up to 20 percent of human mRNA is routinely methylated. Over 5,000 different mRNA molecules contain m6A, which means that this modification is likely to have widespread effects on how genes are expressed.

Seventy-two percent of teenagers experienced reduced hearing ability after a loud concert, new research found. This hearing loss isn't permanent, but repeated exposure to loud noise can be.

"Teenagers need to understand a single exposure to loud noise either from a concert or personal listening device can lead to hearing loss," study researcher M. Jennifer Derebery, of the House Research Institute, said in a statement. "With multiple exposures to noise over 85 decibels, the tiny hair cells may stop functioning and the hearing loss may be permanent."

The researchers tested the hearing of 29 teens before and after a concert, and 72 percent of them had hearing loss. This type of hearing loss is not generally believed to be permanent. It is called a temporary threshold shift and usually disappears within 16 to 48 hours, after which a person's hearing returns to previous levels.

The study was presented May 21 at the American Otologic Society Meeting in Los Angeles and will be published in the journal Otology & Neurotology.

Researchers at The University of Texas at Austin and Washington State University have seen an increased reaction to stress in animals whose ancestors were exposed to an environmental compound generations earlier.

The findings, published in the latest Proceedings of the National Academy of Sciences, put a new twist on the notions of nature and nurture, with broad implications for how certain behavioral tendencies might be inherited.

The researchers--David Crews at Texas , Michael Skinner at Washington State and colleagues--exposed gestating female rats to vinclozolin, a popular fruit and vegetable fungicide known to disrupt hormones and have effects across generations of animals.

The researchers then put the rats' third generation of offspring through a variety of behavioral tests and found they were more anxious, more sensitive to stress, and had greater activity in stress-related regions of the brain than descendants of unexposed rats.

"We are now in the third human generation since the start of the chemical revolution, since humans have been exposed to these kinds of toxins," says Crews. "This is the animal model of that."

"The ancestral exposure of your great grandmother alters your brain development to then respond to stress differently," says Skinner. "We did not know a stress response could be programmed by your ancestors' environmental exposures."

The researchers had already shown exposure to vinclozolin can effect subsequent generations by affecting how genes are turned on and off, a process called epigenetics. In that case, the epigenetic transgenerational inheritance altered how rats choose mates.

DNA is the blueprint for life, and now it can serve as a computer to monitor life's processes. Bioengineers transformed DNA into a one-bit memory system that can record, store and erase data within living cells.

A future DNA memory device could be used to track cell division and differentiation in cancer patients, perhaps, or to monitor what happens as cells get sick or age.

We've seen plenty of body-monitoring computer systems, from chips that can swim through the bloodstream to nanowires that can tap the heart or other muscle. But so far, these systems are limited to a few processes.

This system could work like rewritable memory in your computer, recording and erasing information again and again.

The system flips DNA sequences back and forth between two states, basically the genetic equivalent of a binary switch. One DNA orientation equates to "one," and the other equates to "zero."

The process uses an enzyme taken from bacteriophages to cut and recombine the DNA. The recombinase enzyme moves to a particular swath of DNA and flips it around so its base pairs basically read backward, and a second signal flips it back.

Advertisers want to know all your quirky neuroses. That's because new research reveals that consumers are more likely to be persuaded by an advertisement that targets their personality type than one that caters to their demographic.

So, instead of creating ads that appeal to women between the ages of 25 and 40, for example, marketers should be focusing on targeting ads to nervous people or assertive people or impatient people, according to a study in the current issue of Psychological Science. The research suggests advertisements can be more effective when they are tailored to the unique personality profiles of potential consumers.

"Persuasive messages are often targeted toward specific demographic groups," said study author Jacob Hirsh, from the University of Toronto's Rotman School of Management. "We wanted to see whether their effectiveness could be improved by targeting personality characteristics that cut across demographic categories."

The research examined the reactions of more than 300 consumer to five different cellphone advertisements, each designed to target one of the five major trait domains of human personality: extraversion, agreeableness, conscientiousness, emotional stability and openness to experience.