Dolphins in Australia have been observed using tools, and they seem to pass on their specialist knowledge to others. This is the first time cultural transmission has been confirmed in a marine mammal. Lacking hands, dolphins are limited in what they can do with a tool, but some bottlenose dolphins in Shark Bay, Western Australia, have devised a way to break marine sponges off the seafloor and wear them over their snouts when foraging. “We believe that they use sponges as a kind of glove to protect their sensitive rostrums when they probe for prey in the substrate,” says Michael Krützen, formerly of the University of New South Wales in Sydney, Australia, and now at the University of Zurich, Switzerland. Most sponges are flat, but tool-using dolphins select conical ones that will not fall off their snouts. The majority of dolphin “spongers” are females. To discover whether tool-use is a genetic trait, or one transmitted culturally, Krützen and colleagues analysed DNA from 13 of 15 spongers, only one of which was male, and 172 non-spongers. They found that most spongers were maternally related - sharing the same mitochondrial DNA, which is only transmitted through the female line. A comparison of their nuclear DNA showed that the spongers were closely related, suggesting that spongers are descendants of a recent “Sponging Eve”. However, the pattern of sponging among the dolphins could not be explained by a “gene for sponging” - the trait’s pattern of inheritance just did not fit. The researchers conclude that the behaviour is culturally transmitted, presumably by mothers teaching the skills to their sons and daughters, although they have not actually observed this feat in action. © Copyright Reed Business Information Ltd.

Keyword: Evolution
Link ID: 7453 - Posted: 06.24.2010

There are strong reasons to support the practice of prescribing heroin to drug misusers, researchers claim. A University of Amsterdam team says the treatment is cost-effective, even though it is expensive. The British Medical Journal study found the cost to health services was offset by savings linked to crime reduction. Supervised medical prescription of heroin - a class A drug in the UK - is controversial. UK experts said a range of treatments should be available. Previous research has shown supervised medial prescription of heroin improves the physical and mental health, and ability to function normally in society, of users who cannot be successfully treated using just methadone - a synthetic narcotic used to treat heroin addiction. The Dutch scientists looked at 430 heroin addicts who were taking part in methadone maintenance programmes in six cities in the Netherlands. Before they took part in the study, they had frequently engaged in illegal activities to acquire money or drugs. The addicts were given either methadone plus heroin, or methadone alone. The patients were then assessed after a year of treatment. Those given the combination treatment reported a better quality of life, compared to those given methadone alone. And although the costs of co-prescription were found to be considerably higher, they were offset by lower policing costs and reduced costs of crime against property because addicts were not breaking the law to fund their habit. The average total net savings amounted to 12,793 euros (about Ł8,600) per patient per year. (C)BBC

Keyword: Drug Abuse
Link ID: 7452 - Posted: 06.06.2005

By Amanda Schaffer Elisabeth Lloyd, a soft-spoken philosopher of biology, didn't expect to serve up jokes on Saturday Night Live when she published an academic book late last month. But The Case of the Female Orgasm hit a cultural G spot. After the New York Times featured Lloyd in last Tuesday's science section, her phone started ringing, and by Thursday she was chatting about orgasms with Barbara Walters and the other women on ABC's The View. Saturday Night Live parodied the book as a "case of" mystery that's "a real departure for The Hardy Boys." Why the fuss? Lloyd's central claim is not new. But her study of evolution and orgasm offers the most thorough and serious treatment of the subject to date—and strongly rejects the claim that orgasm in women serves an evolutionary purpose. Lloyd has scrutinized 21 evolutionary accounts of female orgasm and makes a convincing case for the single account that treats orgasm as a happy accident, a byproduct of the role that male orgasm plays in reproduction and the sharing of early embryonic tissue by the male and female genitalia. The other 20 theories she dismisses as illogical or incompatible with data on women's sexuality. This time the press has it right. Lloyd's analysis is worth all the attention. She hasn't definitively settled the debate: One new line of inquiry could pose a challenge to her thesis. But it probably wouldn't be a fatal one, so score one for the orgasm as pure pleasure. That approach was first advanced in 1979 by anthropologist Donald Symons. He argued that orgasm is possible in women because it is crucial in men. Embryos of both sexes have a common body plan early on, so when male orgasm is selected for by evolution, female orgasm comes along for the ride. Symons' explanation, dubbed the "byproduct account," was never popular among biologists. ©2005 Washingtonpost.Newsweek Interactive Co. LLC

Keyword: Sexual Behavior; Evolution
Link ID: 7451 - Posted: 06.24.2010

A promising animal model of epilepsy became even more valuable with the demonstration that the course of the disorder closely parallels that of one of the most common forms of epilepsy in humans. In an article published online June 6, 2005, in the Annals of Neurology, researchers at St. Justine Hospital at the University of Montreal in Canada report that prolonged fever-related seizures in rat pups with underlying brain malformations lead to epilepsy in the rats in adulthood. The article is available via Wiley InterScience at http://www.interscience.wiley.com/journal/ana. Fever-related, or 'febrile,' seizures are not uncommon in young children and usually have no apparent lasting consequences. However, researchers have noted for a long time that people with temporal lobe epilepsy are more likely to have experienced atypical childhood febrile seizures--ones that occur at lower fever temperatures and last for a long time. "Our results stress the importance of a careful evaluation of children with atypical febrile seizures. Early identification of children at risk of developing epilepsy could lead to neuroprotective treatments that could prevent the development of later epilepsy," said senior author Lionel Carmant, M.D., of the Sainte-Justine Hospital at the University of Montreal in Canada. Doctors have long debated whether atypical childhood febrile seizures lead to epilepsy later in life. Researchers have had to consider the alternate possibility that these seizures are merely another manifestation of an underlying disease process that will lead to epilepsy with or without atypical febrile seizures.

Keyword: Epilepsy
Link ID: 7450 - Posted: 06.06.2005

An effort to create the first computer simulation of the entire human brain, right down to the molecular level, was launched on Monday. The “Blue Brain” project, a collaboration between IBM and a Swiss university team, will involve building a custom-made supercomputer based on IBM’s Blue Gene design. The hope is that the virtual brain will help shed light on some aspects of human cognition, such as perception, memory and perhaps even consciousness. It will be the first time humans will be able to observe the electrical code our brains use to represent the world, and to do so in real time, say Henry Markram, director of Brain and Mind Institute at the Ecole Polytecnique Fédérale de Lausanne (EPFL), Switzerland. It may also help in understanding how certain malfunctions of the brain’s “microcircuits” could cause psychiatric disorders such as autism, schizophrenia and depression, he says. Until now this sort of undertaking would not be possible because the processing power and the scientific knowledge of how the brain is wired simply was not there, says Charles Peck, IBM’s lead researcher on the project. “But there has been a convergence of the biological data and the computational resources,” he says. But efforts to map the brain’s circuits and the development of the Blue Gene supercomputer, which has a peak processing power of at least 22.8 teraflops, now make this possible. © Copyright Reed Business Information Ltd.

Keyword: Robotics
Link ID: 7449 - Posted: 06.24.2010

La Jolla, Calif.– A newborn baby moves, breathes and cries in part because a network of nerves called motor neurons carry signals from the infant's brain and spinal cord to muscles throughout its body. Thanks to new research by scientists at the Salk Institute for Biological Studies, we are closer to understanding how these complicated network connections are wired up during embryonic development. Salk researchers have discovered that the same chemicals (called neurotransmitters) that are responsible for nerve signals are also involved in the wiring of synapses, the network's crucial contact points between nerves, or between nerves and muscle cells. The study, published in the May issue of the journal Neuron, showed that as the motor neurons grow from their home base in the spinal cord towards muscles throughout the body, they release two opposing chemical signals. These signals act to preserve synapses that link a motor neuron to its correct muscle cell. 'Spare' sites for potential synapses that fail to team up with a motor neuron are dismantled. "Our study provides the first evidence in a living animal system that the neurotransmitters themselves are sculpturing the developing nervous system," said Kuo-Fen Lee, Associate Professor at the Salk, who heads the research team reporting its results in Neuron.

Keyword: Development of the Brain
Link ID: 7448 - Posted: 06.24.2010

UCLA scientists have discovered how chronic exposure to low levels of carbon monoxide (CO) damages the inner ear of young rats, resulting in permanent hearing loss. At the Ca/OSHA's exposure limit of 0.0025 percent -- or 25 parts per million CO in the air -- the gas creates oxidative stress, a condition that damages the cochlear cells, leading to impairment of the auditory nerves. Tobacco smoke, gas heaters, stoves and ovens all emit CO, which can rise to high concentrations in poorly ventilated homes. Infants and children are particularly vulnerable to CO exposure because they spend a great deal of time in the home. No policies exist to regulate CO in the home. Many commercial home monitors sound an alarm only 20 minutes after CO concentrations reaches 70 parts per million -- nearly three times the 25 parts per million limit set by Cal/OSHA. This is the first time that inhaled CO has been linked to oxidative stress, a known risk factor in many disorders, including Alzheimer's, Parkinson's, multiple sclerosis, Lou Gherig's disease and cardiovascular disease. Tobacco smoke, which contains CO, aggravates many of these diseases. The UCLA findings highlight the need for policy makers to reexamine the regulation of car exhaust, tobacco smoke, smog, and heating and cooking appliances.

Keyword: Neurotoxins; Hearing
Link ID: 7447 - Posted: 06.04.2005

ST. LOUIS, MISSOURI--A new kind of gene therapy can cure the metabolic disorder phenylketonuria in mice, researchers reported here this week at the annual meeting of the American Society of Gene Therapy. The method uses a viral protein rather than a virus itself to insert a corrective gene into a specific location in the mouse's DNA, making it a potentially safer way of delivering new genes. Traditional gene therapy involves using a virus to deliver normal copies of genes into a subject's body. But because such genes integrate into a host's genome at random locations, the approach can disrupt normal genes, like those that guard against cancer. Such risks recently became clear when three patients in a gene therapy trial in France that had successfully treated 10 children with X-linked severe combined immunodeficiency disease later developed leukemia (ScienceNOW, 7 March). Ideally, researchers would like to place a corrective gene only in a specific, safe location away from other genes. Geneticist Michele Calos's group at Stanford University School of Medicine in California has invented such a method using a type of enzyme called an integrase, which is used by viruses that infect bacteria and which latches onto a specific sequence of the host cell's DNA. Li Chen in Savio Woo's lab at Mount Sinai School of Medicine in New York City wondered if he could use a similar approach to treat mice with phenylketonuria--a disease that prevents people from making enough of the liver enzyme phenylalanine hydroxylase (PAH). As a result, the body cannot convert the amino acid phenylalanine to tyrosine, and the buildup of phenylalanine leads to severe mental retardation. Currently, the main treatment for phenylketonuria is a strict diet low in phenylalanine. Chen made loops of bacterial DNA containing an integrase and a good copy of the PAH gene, and then injected these plasmids into a mouse's tail vein. After three injections, the mice made more PAH enzyme and their blood levels of phenylalanine fell to within the normal range for more than 6 weeks, Chen said. Another sign that it worked: the mice's fur turned from gray to black because they now had the tyrosine they needed to make melatonin. Copyright © 2005 by the American Association for the Advancement of Science.

Keyword: Development of the Brain; Genes & Behavior
Link ID: 7446 - Posted: 06.24.2010

Abnormal prion proteins are little understood disease agents involved in causing horrific brain-wasting diseases such as Creutzfeldt-Jacob disease in people, mad cow disease in cattle and chronic wasting disease in deer and elk. Now, new research suggests that a variant form of abnormal prion protein — one lacking an “anchor” into the cell membrane — may be unable to signal cells to start the lethal disease process, according to scientists at the Rocky Mountain Laboratories (RML), part of the National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health. “This work provides novel insights into how prion and other neurodegenerative diseases develop and it provides tantalizing clues as to how we might delay or even prevent such diseases by preventing certain cellular interactions,” notes NIAID Director Anthony S. Fauci, M.D. A paper describing the research was released online today by the journal Science. Drawing on experimental concepts first developed at RML a decade ago, the research team exposed two groups of 6-week-old mice to different strains of the agent that causes scrapie, a brain-wasting disease of sheep. Within 150 days of being inoculated with the natural form of scrapie prion protein, all 70 mice in the control group showed visible signs of infection: twitching, emaciation and poor coordination. In contrast, the scientists observed 128 transgenic mice — those engineered to produce prion protein without a glycophosphoinositol (GPI) cell membrane anchor — for 500 to 600 days and saw no signs of scrapie disease. Subsequent electron microscopic examinations at UCSD, however, confirmed that they produced amyloid fibrils, an abnormal form of prion protein, and that they even had brain lesions. More remarkably, according to Dr. Chesebro, the diseased brain tissue resembled that found in Alzheimer’s disease rather than in scrapie.

Keyword: Prions
Link ID: 7445 - Posted: 06.24.2010

Alison Abbott Neuropathic pain is a devastating nerve disorder for which medicine has no good cure. But a group of scientists at the University of Michigan in Ann Arbor have shown the pain can be eased by a gene transfer technique, in rats at least. Neuropathy, degeneration of the nerves, is a common complication of diabetes and other diseases. When the damage occurs to sensory nerves, which transmit pain, temperature and touch signals to the brain, patients suffer. The lightest touch causes unbearable burning sensations, and temperatures that would normally be perceived as pleasantly warm feel furnace-hot. Worse still, the pain often occurs in the absence of any stimulus at all. Drugs do little good. One of the many factors known to be involved in the generation of neuropathic pain is a reduction of the neurotransmitter GABA in the spinal cord, because GABA has a damping effect on nerve transmission. Scientists know that an enzyme called glutamic acid decarboxylase (GAD) can increase production of GABA. So the Michigan researchers wondered whether they could boost GABA and relieve pain by adding a gene that encodes for GAD into the spinal cord. ©2005 Nature Publishing Group

Keyword: Pain & Touch
Link ID: 7444 - Posted: 06.24.2010

Bruce Bower Some people smell fear in potential business partners. Others smell a rat. But individuals who smell a certain brain hormone become unusually trusting of others in financial transactions, according to a new report. Men who inhale a nasal spray spiked with oxytocin give more money to partners in a risky investment game than do men who sniff a spray containing no active ingredient, say economist Ernst Fehr of the University of Zurich and his colleagues. Previous studies of nonhuman animals had suggested that oxytocin in the brain encourages long-term mating in pairs of adults and nurturing behaviors by mothers toward their offspring. This substance, which works as both a hormone and a neurotransmitter, fosters the trust needed for friendship, love, families, economic transactions, and political networks, Fehr proposes. "Oxytocin specifically affects an individual's willingness to accept social risks arising through interpersonal interactions," he and his colleagues conclude in the June 2 Nature. The scientists studied oxytocin's influence on male college students playing an investment game. Each of 58 men was paid $64 to participate in the experiment. Copyright ©2005 Science Service.

Keyword: Hormones & Behavior; Emotions
Link ID: 7443 - Posted: 06.24.2010

Janet Raloff and Ben Harder Infant boys who were exposed in the womb to modest concentrations of certain common plasticizers and solvents developed genital changes including smaller-than-normal penises, a new study finds. The results from this study of 85 boys are consistent with what researchers have seen in laboratory animals treated with the chemicals, which are called phthalates. In such tests, the substances impair fetal production of testosterone and other male sex hormones (SN: 4/3/99, p. 213: http://www.sciencenews.org/pages/sn_arc99/4_3_99/fob3.htm). In the current study, mothers with the highest phthalate exposures bore boys with slightly less space between the gonads and anus than did mothers with less phthalate exposure, as gauged by the women's urine concentrations of the chemicals during pregnancy. Moreover, boys with a short anogenital distance tended to have smaller penises and were far more likely to have testes that didn't descend properly into the scrotum. Anogenital distance is typically longer in males than in females. In rodents, prenatal phthalate exposure can erase this difference, says Paul M.D. Foster of the National Institute of Environmental Health Sciences in Research Triangle Park, N.C. He's shown that this shortening in male animals can signal major permanent impairments in reproductive organs (SN: 9/2/00, p. 152: http://www.sciencenews.org/articles/20000902/bob9.asp). Copyright ©2005 Science Service.

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 7442 - Posted: 06.24.2010

The dyslexic brain may have a general problem forming perceptual categories, including the templates for printed letters and speech sounds, say USC neuroscientists. This is reflected in a reduced ability to filter out visual "noise" that can obscure a pattern, the researchers suggest. Their novel hypothesis, published in the current issue of Nature Neuroscience, raises broader questions: Does the dyslexic brain's trouble with patterns and noise extend to other senses? Does poor filtering inhibit the formation of perceptual categories? Or is poor formation of categories the root cause of dyslexics' problem with noise? Dyslexia is the most common and perhaps least understood reading disability. Affecting millions of Americans, it has a history of uncertain explanations. An old, discredited, but persistent view is that dyslexics jumble their letters. In the 1980s, the subtler "magnocellular hypothesis" gained favor with some scientists. Named for a type of neuron, the hypothesis held that dyslexics struggle to process rapid visual signals. Language comprehension also requires rapid processing ability. The Nature Neuroscience study casts doubt on the magnocellular hypothesis. The lead author was Anne Sperling, a graduate of USC's neuroscience program whose Ph.D. thesis was based on the study. The research team, which included Zhong-Lin Lu and Franklin Manis, professors of psychology in the USC College of Letters, Arts and Sciences, and Mark Seidenberg of the University of Wisconsin, Madison, asked dyslexic and non- dyslexic children to identify patterns presented with and without visual noise.

Keyword: Dyslexia
Link ID: 7441 - Posted: 06.04.2005

Palaeontologists think they have found a way to tell whether dinosaur fossils are from males or females. Writing in Science, a US team describe a specialised type of bone layer in fossils from a T. rex which is similar to one found in female birds. In birds, the special tissue is called medullary bone and is laid down in the limbs of females when they lay eggs. The bone tissue found in the dinosaur fossils most closely resembles the medullary bone of emus and ostriches. The scientists behind the discovery say it reinforces the evolutionary links between dinosaurs and birds because it suggests their bodies went through similar processes during egg-laying. "In addition to demonstrating gender, it also links the reproductive physiology of dinosaurs to birds very closely. It indicates that dinosaurs produced and shelled their eggs much more like modern birds than like modern crocodiles," said co-author Dr Mary Schweitzer, of North Carolina State University in Raleigh. Some researchers have proposed that female dinosaurs differed from males in the shapes of their skeletons or in the forms of their head ornamentation. But these theories have been impossible to prove. The medullary bone deposited by female birds when laying eggs is triggered by increasing levels of gonadal hormones produced on ovulation. This tissue is rich in calcium and contains many small blood vessels, providing a ready source of calcium for eggs. (C)BBC

Keyword: Sexual Behavior; Evolution
Link ID: 7440 - Posted: 06.03.2005

By ANDREW POLLACK Shares of Biogen Idec and Elan fell yesterday on news that a fourth patient may have developed the life-threatening brain infection that prompted the companies to halt sales of their multiple sclerosis drug Tysabri earlier this year. If the fourth case of the normally extremely rare infection is confirmed, it would make it more difficult for the drug to return to the market, doctors and analysts said. The new case might indicate the drug is more dangerous than previously thought because it appears the fourth patient might have taken the drug for a substantially shorter time than the other three. Lenore Gelb, a spokeswoman for the Food and Drug Administration, said yesterday that the agency had "been notified by Biogen of a fourth case of symptoms that are suggestive of" the infection. She said the agency was in discussions with Biogen, which is investigating the case. The possibility of a fourth afflicted Tysabri user was first reported yesterday by The Boston Globe, which obtained data on the patient through a freedom of information request to the F.D.A. Tim Hunt, a spokesman for Biogen Idec, said the company would not confirm or deny the report because it was no longer commenting on individual cases. He said the company was evaluating the medical records of all the patients who took Tysabri and hoped to have a complete report by the end of the summer. Copyright 2005 The New York Times Company

Keyword: Multiple Sclerosis
Link ID: 7439 - Posted: 06.03.2005

By NICHOLAS WADE A team of scientists at the University of Utah has proposed that the unusual pattern of genetic diseases seen among Jews of central or northern European origin, or Ashkenazim, is the result of natural selection for enhanced intellectual ability. Intelligence and GeneticsThe selective force was the restriction of Ashkenazim in medieval Europe to occupations that required more than usual mental agility, the researchers say in a paper that has been accepted by the Journal of Biosocial Science, published by Cambridge University Press in England. The hypothesis advanced by the Utah researchers has drawn a mixed reaction among scientists, some of whom dismissed it as extremely implausible, while others said they had made an interesting case, although one liable to raise many hackles. "It would be hard to overstate how politically incorrect this paper is," said Steven Pinker, a cognitive scientist at Harvard, noting that it argues for an inherited difference in intelligence between groups. Still, he said, "it's certainly a thorough and well-argued paper, not one that can easily be dismissed outright." "Absolutely anything in human biology that is interesting is going to be controversial," said one of the report's authors, Dr. Henry Harpending, an anthropologist and a member of the National Academy of Sciences. Copyright 2005 The New York Times Company

Keyword: Intelligence; Genes & Behavior
Link ID: 7438 - Posted: 06.03.2005

By Randy Dotinga Scientists are scanning brain activity in the hopes of catching sight of the physical mechanisms that determine whether you prefer Coke over Pepsi. The nascent research, known as "neuromarketing," could one day lead to new advertising strategies that directly stimulate hard-wired mental reflexes rather than appealing to fuzzy consumer attitudes. "The hope in neuromarketing is that there's some process in the brain that is a better predictor of whether people will actually buy things than what we already have," said Colin Camerer, professor of business economics at the California Institute of Technology. Over the past several years, American and German neuroscientists have been using functional magnetic resonance imaging, or fMRI, brain scans to observe what happens in the brain when people evaluate things like beer, cars and politicians. The latest big finding came from neuroeconomists, who study how people make decisions about everything from buying a lottery ticket to deciding whether to avoid sitting next to a creepy guy on the bus. Earlier this month, Stanford University researchers reported that they've pinpointed the parts of the brain that handle two major parts of a choice -- figuring out how nifty something is and then calculating how likely it is that you'll get it. The study, published in the May 11 issue of The Journal of Neuroscience, was designed to analyze different parts of the decision-making process. Researchers told subjects to press a button quickly when they saw a target on a screen. Before the target appeared, the subjects were told how much they might win during that round, from nothing to $5. © Copyright 2005, Lycos, Inc.

Keyword: Emotions; Brain imaging
Link ID: 7437 - Posted: 06.24.2010

A male fly's sexual courtship of a female fly is a complicated business of tapping, singing, wing vibration, and licking, but a single gene is all that is needed to produce this complex behavior, according to new research published in this week's issue of the journal Cell. The gene encodes the Fruitless protein. Male and female flies carry different versions of the fruitless protein, as a result of sex-specific splicing of the mRNA. The male form of Fruitless is critical for the male courtship ritual and males' preference for mating with females, as previous studies have shown. Now, Barry J. Dickson and Ebru Demir of the Institute of Molecular Biotechnology of the Austrian Academy of Sciences show just how intimately fruitless is linked to these stereotypically male behaviors. They discovered that female flies with the male version of fruitless behave like males, directing at other females a sexual display nearly identical to their male counterparts. Female flies with the male version of the protein also make amorous advances toward male flies that express female pheromones. In these cases, "we have been able to reverse the sex roles during Drosophila courtship," Dickson and Demir say. Dickson and Demir created male-spliced versions of fruitless in female flies and female-spliced versions in male flies. Males with the female version of fruitless "barely court at all" when paired with virgin female flies in an observation chamber, according to the researchers.

Keyword: Sexual Behavior; Genes & Behavior
Link ID: 7436 - Posted: 06.03.2005

Roxanne Khamsi Male and female fruitflies have been engineered to switch courtship roles, through the manipulation of a single gene. The study, which appears in Cell1, shows how a simple genetic adjustment can cause a dramatic change in sexual behaviour. "It was quite something to see," says Barry Dickson, who is one of the authors and is based at the Austrian Academy of Sciences in Vienna. The mating behaviours of the Drosophila fruitfly are a far cry from intricate Hollywood romance. The male performs a series of tapping and tilting movements, to which the female usually responds if she has not recently mated. Females, in contrast, never court at all. But Dickson and his colleague Ebru Demir reversed this behaviour by designing female flies with the male version of a gene called fruitless. These insects initiated courtship with other females as often as their male counterparts did. The tweaked female flies could only be encouraged to court males if the males were designed to emit female pheromones, a form of natural chemical attractant. When male flies were given the female version of the fruitless gene, they stopped courting and became passive about sex. ©2005 Nature Publishing Group

Keyword: Sexual Behavior; Genes & Behavior
Link ID: 7435 - Posted: 06.24.2010

A single gene which hastens a fruit fly larva’s change into a buzzing sexual adult has been unveiled by researchers. This “maturity gene” could help scientists understand the stormy process of growing up in all animals and maybe even generate ways to manipulate the length of childhood in higher vertebrates, including humans. “It’s metamorphosis in insects and puberty in humans. Either way, it’s just the onset of adult form. Anyone who has watched a child mature knows that they change in very dramatic ways,” says Carl Thummel at the University of Utah in Salt Lake City, US, one of the study authors. The timing of maturity is a complex process, influenced by factors like the availability food and genetics. But the molecular pathways remain similar throughout the animal kingdom. For example, the steroid hormones oestrogen and testosterone play an important role human adolescence, while the steroid ecdysone drives maturation in flies. To better understand the network of signals that control metamorphosis in flies, Thummel and his colleagues reduced the function of a receptor called DHR4 in the fruit fly Drosophila melanogaster. To their surprise, they found that mutant flies with reduced DHR4 activity had a shorter juvenile phase and proceeded to adulthood at a smaller size. The immature larvae had cut short their youthful feeding frenzy by a day. This feeding session - crucial during the maturation process from hatching to pupae - usually lasts about four days. © Copyright Reed Business Information Ltd

Keyword: Sexual Behavior; Genes & Behavior
Link ID: 7434 - Posted: 06.24.2010