By Jennifer Viegas, Discovery News — Two types of ants from the family that includes carpenter ants, as well as the common "sidewalk" ants that often march through gardens, serve as the poison source for certain poisonous frogs, according to a new study. The ants generate alkaloids, which are powerful substances that can produce physiological effects in humans and animals. The study, published in the current Proceedings of the National Academy of Sciences, presents the first evidence for alkaloids in the ant subfamily Formicinae. Poisonous frogs are able to eat loads of the toxin-generating ants and are able to concentrate the ants' alkaloids into their bodies and skin. The frogs come from the dendrobatid family, a group commonly referred to as poisonous dart frogs, which are the frogs that Central and South American Emberá and Noanamá Chocó Indians use to create poison darts for their blowguns. Copyright © 2004 Discovery Communications Inc.

Keyword: Neurotoxins
Link ID: 5463 - Posted: 06.24.2010

(Kingston, ON) – A surprising discovery by Queen's researchers helps explain why fish swimming in icy sea water don't freeze. The team, led by Biochemistry Professor Peter Davies, has identified a new "antifreeze" protein found in the blood of winter flounder enabling the fish to withstand temperatures as low as -1.9 degrees Celsius: the freezing point of sea water. The antifreeze plasma proteins (AFPs) do this by binding irreversibly to ice crystals and preventing them from growing. Until now, it has been a mystery how these fish survive in polar oceans, since the previously identified "type I" AFP associated with winter flounder only provides 0.7oC of freezing point depression, which in combination with blood solutes, only protects the fish down to -1.5 degrees Celsius. "This finally explains the 'critical gap' of 0.4 degrees," says Dr. Davies, a Queen's Canada Research Chair in Protein Engineering. "The winter flounder has been studied extensively by a number of laboratories over the past 30 years, but this antifreeze protein escaped everyone's notice. We're excited to have found it."

Keyword: Evolution
Link ID: 5462 - Posted: 06.24.2010

Migrating birds stay on track because of chemical reactions in their bodies that are influenced by the Earth’s magnetic field, a UC Irvine-led team of researchers has found. The birds are sensitive even to rapidly fluctuating artificial magnetic fields. These fields had no effect on magnetic materials such as magnetite, indicating that the birds do not rely on simple chunks of magnetic material in their beaks or brains to determine direction, as experts had previously suggested. The results are reported in the May 13 issue of Nature. The study is the first to reveal the mechanism underlying magnetoreception – the ability to detect fluctuations in magnetic fields – in migratory birds. In the study, Thorsten Ritz, assistant professor of physics and astronomy, and colleagues exposed 12 European robins to artificial, oscillating magnetic fields and monitored the orientation chosen by these birds. The stimuli were specially designed to allow for responses that could differ depending on whether birds used small magnetic particles on their bodies or a magnetically sensitive photochemical reaction to detect the magnetic field. © Copyright 2002-2004 UC Regents

Keyword: Animal Migration
Link ID: 5461 - Posted: 06.24.2010

Levels of testosterone in the womb may have profound effects on a person's social development. The findings might also explain why men are four times as likely as women to suffer from autism. The study is the latest in a series on a group of 58 children born in 1996 and 1997. Simon Baron-Cohen's team at the Autism Research Centre in Cambridge, UK, measured testosterone levels in the amniotic fluid of the babies' mothers while pregnant. This is presumed to reflect levels in the babies themselves. The team has already found that the babies with higher fetal testosterone levels had a smaller vocabulary and made eye contact less often when they were a year old. And a study by another group has shown that eight-year-old girls who had high fetal levels of the hormone performed better at tasks such as mentally rotating a two-dimensional figure. © Copyright Reed Business Information Ltd.

Keyword: Hormones & Behavior; Autism
Link ID: 5460 - Posted: 06.24.2010

DURHAM, N.C. -- Until now, primatologists believed lemurs to be primitive, ancient offshoots of the primate family tree, with far less intelligence than their more sophisticated cousins, monkeys, apes and humans. But at the Duke University Primate Center, with the gentle touch of his nose to a computer screen, the ringtail lemur called Aristides is teaching psychologist Elizabeth Brannon a startling scientific lesson -- that lemurs are, indeed, intelligent creatures. Brannon is using touch-screens, Plexiglas boxes holding raisins and buckets hiding grapes to establish that ringtails such as Aristides and his mongoose lemur cousins possess a surprising ability to learn sequences of pictures and to discriminate quantities. While Brannon's work is still only at a preliminary stage, its initial results lead her to believe that such studies could mark the dawning of a new appreciation of lemur intelligence. Such research could offer important evolutionary insights into the nature of intelligence in primates, Brannon said, since lemurs are living models for the ancient primate mind. "Prosimians," including lemurs and related species split off from the primate line some 55 million years ago, evolving independently from the line that led to anthropoids and humans.

Keyword: Intelligence; Evolution
Link ID: 5459 - Posted: 05.13.2004

When jet lag or oft-changing work shifts make you feel out of synch, it's probably not your imagination. New research led by a University of Washington biologist demonstrates that there are at least two circadian clocks in the mammal brain, one that sticks strictly to an internal schedule and another that can be altered by external influences such as light and dark. Typically the two clocks are synchronized so that various physical functions are in tune with each other, said Horacio de la Iglesia, a UW assistant professor of biology. But make a long plane trip or switch your 8-to-5 work schedule to begin at midnight and things can get out of kilter. "When you travel to Europe, the rest-activity cycle will adjust relatively quickly. In two or three days you'll probably be sleeping when it's dark," de la Iglesia said. "But your temperature or hormone-release cycles might still be on Seattle time, affecting for instance how well you sleep." A bit of brain tissue called the suprachiasmatic nucleus, a daily pacemaker that regulates rhythms such as sleep and wakefulness, has thousands of cells called neurons with synchronized circadian activities. But the neurons in the nucleus can be grouped into at least two secondary clocks that can become disconnected from one another when exposed to artificial day-night cycles.

Keyword: Biological Rhythms
Link ID: 5458 - Posted: 05.13.2004

Human beings are more aroused by rewards they actively earn than by rewards they acquire passively, according to brain imaging research by scientists at Emory University School of Medicine. Results of the study, led by first author Caroline F. Zink and principal investigator Gregory S. Berns, MD, PhD, of Emory’s Department of Psychiatry and Behavioral Sciences, are published in the May 13 issue of the journal Neuron. The Emory scientists used functional magnetic resonance imaging (fMRI) to measure brain activity in the striatum, which is a part of the brain previously associated with reward processing and pleasure. Although other experiments have studied and noted brain activity associated with rewards, until now these studies have not distinguished between the pleasurable effects of receiving a reward and the "saliency" or importance of the reward. Study volunteers in the Emory experiment were asked to play a simple target-detection computer game. During the game, a money bill appeared occasionally and automatically dropped into a bag of money on the screen. The participant was given the amount of money that dropped in the bag at the end of the game, but because receiving the money had nothing to do with their performance on the computer game, it was not particularly arousing or salient to them. In another version of the game, a money bill occasionally appeared on the screen and the participant had to momentarily interrupt the target detection game and push a button to make the bill drop into the bag.

Keyword: Attention; Learning & Memory
Link ID: 5457 - Posted: 06.24.2010

For the first time, researchers have used a technique called optical imaging to visualize changes in nerve connections when flies learn. These changes may be the beginning of a complex chain of events that leads to formation of lasting memories. The study was funded in part by the NIH's National Institute of Neurological Disorders and Stroke (NINDS) and appears in the May 13, 2004, issue of Neuron.1 Scientists have long been captivated by the questions of how memories form and how they are represented in the brain. The answers to these questions may help researchers understand how to treat or prevent memory problems, drug addiction, and other human ailments. Thousands of changes in gene expression, neuron formation, nerve signaling, and other characteristics may be involved in the formation of just a single memory. Scientists refer to any learning-induced change in the brain as a "memory trace." In the new study, Ronald L. Davis, Ph.D., and colleagues at Baylor College of Medicine in Houston developed fruit flies with special genes that caused the flies' neuronal connections to become fluorescent during nerve signaling (synaptic transmission). They then exposed the flies to brief puffs of an odor while they received a shock. This caused them to learn a new association between the odor and the shock — a type of learning called classical conditioning.

Keyword: Learning & Memory
Link ID: 5456 - Posted: 06.24.2010

BY JAMIE TALAN Scientists have transplanted adult stem cells from the bone marrow of rats into the brains of rat embryos and found that thousands of the cells survive into adulthood, raising the possibility that someday developmental abnormalities could be prevented or treated in the womb. Dr. Ira Black, chairman of the department of neuroscience at the University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, said the cells took on the properties of brain cells, migrating to specific regions and taking up characteristics of neighboring cells. "They exhibited the same flexibility in the living brain as we had observed in culture," said Black, director of the school's Stem Cell Center. His findings were published today in the Journal of Neuroscience. Copyright © Newsday, Inc. Produced by Newsday Electronic Publishing.

Keyword: Stem Cells; Regeneration
Link ID: 5455 - Posted: 06.24.2010

A large dose of caffeine may be the way many of us start the day, but researchers say little and often would do more to help us stay awake. Harvard University researchers say the morning cuppa boosts caffeine levels, but these fall away during the day. They say frequent low doses of caffeine would give people such as shift workers who need to stay awake more of boost. Writing in the journal Sleep, they say caffeine works by interfering with one of the systems which governs sleep. When we sleep, and for how long, is regulated by both the circadian system and the homeostatic system. The circadian system is tuned in to the difference between night and day, and promotes sleep rhythmically, with an internal clock releasing melatonin and other hormones in a cyclical fashion. But the homeostatic system is demand driven - it tells the body it needs more sleep the longer someone has been awake. (C)BBC

Keyword: Sleep
Link ID: 5454 - Posted: 05.12.2004

By RICHARD PÉREZ-PEÑA In the wake of huge tobacco tax increases and a ban on smoking in bars, the number of adult smokers in New York City fell 11 percent from 2002 to 2003, one of the steepest short-term declines ever measured, according to surveys commissioned by the city. The surveys, to be released today, show that after holding steady for a decade, the number of regular smokers dropped more than 100,000 in a little more than a year, to 19.3 percent of adults from 21.6 percent. The decline occurred across all boroughs, ages and ethnic groups. The surveys also found a 13 percent decline in cigarette consumption, suggesting that smokers who did not quit were smoking less. Like similar local and national polls, the surveys counted as smokers all people who said that they had smoked more than 100 cigarettes in their lives and that they now smoked every day or "some days." Copyright 2004 The New York Times Company |

Keyword: Drug Abuse
Link ID: 5453 - Posted: 05.12.2004

By THE ASSOCIATED PRESS WINNIPEG, Manitoba, — David Reimer, a man who was born a boy but raised as a girl in a famous medical experiment, only to reassert his male identity in the last 20 years of his life, died on May 4. He was 38. His family says he committed suicide. Mr. Reimer shared his story about his life in the pages of a book and on Oprah Winfrey's television show. His mother, Janet Reimer, said she believed that her son would still be alive had it not been for the devastating experiment, which led to much emotional hardship. "He managed to have so much courage," she said Sunday. "I think he felt he had no options. It just kept building up and building up." After a botched circumcision operation when he was a toddler, David Reimer became the subject of a study that became known as the John/Joan case in the 60's and 70's. His mother said she was still angry with the Baltimore doctor who persuaded her and her husband, Ron, to give female hormones to their son and raise him as a daughter. Copyright 2004 The New York Times Company

Keyword: Sexual Behavior
Link ID: 5452 - Posted: 06.24.2010

By Jennifer Viegas, Discovery News — Australian scaly cricket males can copulate 50 to 58 times within three to four hours with the same female, which sets the world record for the most copulations per unit time of any creature within the animal and insect kingdom, according to a report in the current Royal Society Biology Letters. The finding puts the insect Ornebius aperta ahead of the previous record holders, lions and tigers. Tigers can mate up to 50 times a day at a rate of five to 15 minutes over the course of five or six days. The research also suggests that "extreme repeated mating" can develop in response to female-imposed limits on copulation. In this case, the limit is due to female crickets that remove sperm and eat it after about three seconds following insertion. Copyright © 2004 Discovery Communications Inc.

Keyword: Sexual Behavior; Evolution
Link ID: 5451 - Posted: 06.24.2010

Epidemic reflects rise in refined sugars. HELEN PEARSON The startling rise in diabetes is perfectly mirrored by our mounting consumption of refined carbohydrates, a new analysis reveals. The study adds to evidence that sugary foods should be eschewed and that public health advice to cut back on fat may have backfired. Levels of obesity and late onset diabetes have risen slowly over the last century and accelerated in the last 40 years. While the problem is most acute in developed countries, there is evidence that rates are starting to increase in developing countries too. Most experts agree that worsening diets and increasingly inactive lifestyles are responsible, but the exact cause is hard to pin down. Simin Liu of the Harvard School of Public Health, Boston, and his co-workers collected information on consumption and food composition for the period between 1909 and 1997. They compared this with data on disease incidence rates from the US Centers for Disease Control and Prevention. © Nature News Service / Macmillan Magazines Ltd 2004

Keyword: Obesity
Link ID: 5450 - Posted: 06.24.2010

The dream of saving and sharing functional magnetic resonance imaging (fMRI) data is quickly becoming a reality, according to Dartmouth researchers who run the fMRI Data Center, which archives and distributes the raw data from studies that track brain activity using fMRI. The Dartmouth researchers wrote an essay in the May issue of Nature Neuroscience about the initial reluctance and gradual acceptance of the center, and they describe the many attributes a center such as theirs offers the scientific community. "The fMRI Data Center was created with sharing information in mind," says John Van Horn, the lead author on the paper and a Research Associate Professor of Psychological and Brain Sciences. "We wanted to advance and expand the cognitive neuroscience field by making the raw data accessible to more people for free." According to the essay, the faculty who created the fMRI Data Center in 2000 were met with initial resistance from fellow neuroscientists. Some researchers were hesitant to give away their data; some questioned whether new science could arise from old data; and others thought that the technical hurdles could not be overcome. Despite these concerns, the Dartmouth group went ahead and teamed up with the Journal of Cognitive Neuroscience and made it a requirement to include raw fMRI data when submitting research to the publication. With initial support from the National Science Foundation, the W.M. Keck Foundation and the National Institute of Mental Health, the computer equipment was purchased and fMRI Data Center was established. Copyright © Trustees of Dartmouth College, All Rights Reserved

Keyword: Brain imaging
Link ID: 5449 - Posted: 06.24.2010

Preadolescents who reported high levels of conduct problems were nearly four times as likely to have experienced an episode of depression in early adulthood than were children who reported low rates of conduct problems, according to a new University of Washington study. The research published in the Journal of the American Academy of Child and Adolescent Psychiatry looked at possible links between early childhood behavior problems and depression, violence and social phobia at age 21. The study collected data on children when they were 10 or 11 years old and again a decade later. It found that 20 percent of them had suffered from depression in the previous year as young adults and 21 percent had committed two or more violent acts. Seventeen percent experienced social phobia, an anxiety disorder marked by an unreasonable fear of social situations involving strangers, of being judged in such settings and avoiding those kinds of situations. In some cases, the young people in the study met the criteria for two or all three of these disorders.

Keyword: Depression; Development of the Brain
Link ID: 5448 - Posted: 05.12.2004

Researchers at the University of Warwick have for the first time been able to detail how and why specific neurons in the brain control the hunger response. They have revealed a set of pacemaker nerve cells in the brain that appear to underlie the drive to feed which itself feeds on a complex web of signals. The level of complexity they have found is such that the system could be much more at risk of serious repercussions from a single error in how those signals are processed than anyone had previously thought. Any number of a range of errors could lead to over activity of these pacemaker cells and explain why many people find difficulty in eating less. In the research, published in the May Issue of Nature Neuroscience, Dr David Spanswick and his research team in the University of Warwick’s Department of Biological Sciences, looked at a part of the brain called the hypothalamic arcuate nucleus which was known to deal with hunger and satiety signals but how it achieves this is poorly understood. The University of Warwick team have identified very specific neurons that act as feeding “pacemakers”. This specific group of neurons- which they have dubbed the “ARC pacemaker” produce regular bursts of electrical activity. However these cells integrate and process a wide variety of signals indicating the energy needs of the body signals most often transmitted by the use of chemical messengers such as hormones like ghrelin, released from the gut and leptin from fat cells.

Keyword: Obesity
Link ID: 5447 - Posted: 06.24.2010

By Melissa Jackson Ray has not been to the West End theatre for about 25 years, despite his yearning to see a play. He finds it difficult to do most things people take for granted, like walking in the park or going shopping. Ray has suffered from agoraphobia - a fear of open spaces and public places - for the best part of his adult life. He is overcoming his condition and now wants to help others do the same with a new scheme to help agoraphobics "walk to freedom". Ray's agoraphobia started out of the blue 24 years ago when he had the first of many inexplicable and irrational panic attacks. His life would never be the same again. He said: "One day at work I started to panic. I didn't understand what it was and tried to ignore it. "It didn't make sense." The panic attacks became more frequent and began to destabilise him. "I could have been in a chip shop and something would cause me to panic, but I couldn't explain it." A pattern started to emerge whereby he was forced to avoid situations and places because he feared the onset of a panic attack. It became progressively worse - and a panic attack could happen anywhere at any time.

Keyword: Emotions
Link ID: 5446 - Posted: 05.11.2004

By DENISE GRADY People who spend long hours in the summer sun have an increased risk later in life of developing an eye disease that can cause blindness, researchers have found. But sunglasses and hats that shade the eyes can prevent some of the damage. The disease, age-related maculopathy, is the leading cause of vision loss in older people in the United States. Scientists think people who develop the disease may have a genetic predisposition to it, brought out by an environmental exposure to something like sunlight. As the population ages, the number of people who are blind or suffering from impaired vision from the disease is expected to increase significantly, according to the National Eye Institute. Patients begin losing their eyesight as abnormal blood vessels and opaque deposits form on the retina, the delicate layer of light-sensitive cells at the back of the eye. There is no highly effective treatment for the disease, although zinc and antioxidants like vitamins C and E are recommended. Copyright 2004 The New York Times Company

Keyword: Vision
Link ID: 5445 - Posted: 05.11.2004

By VICKY LOWRY Debra and Patrick Doyle of Aspen, Colo., go skiing every weekend in the winter and, in summer, take long mountain bike rides in the hilly terrain where they live. What helps this 36-year-old couple feel so energetic? They say it is the cans of Red Bull they consume every morning. "It jump-starts my day," Ms. Doyle said of the so-called energy drink, made in Austria and sold in supermarkets and delicatessens around the United States. Once the province of young extreme athletes and the nightclub crowd, which mixes it with vodka, Red Bull has gone mainstream. Sleepy college students drink it because they say they like its amphetamine-like effect; weekend athletes vouch for the buzz it gives them while exercising. A Red Bull spokeswoman said 1.5 billion cans of the drink were consumed worldwide in 2003, a 10 percent increase from the previous year. In the United States, Red Bull controls roughly 50 percent of the $1 billion energy drink market. Copyright 2004 The New York Times Company

Keyword: Drug Abuse
Link ID: 5444 - Posted: 05.11.2004