Yearly Archives: 2007

How Poisonous Mushrooms Cook Up Toxins:

Alpha-amanitin is the poison of the death cap mushroom, Amanita phalloides. The Michigan State University plant biology research associate was looking for a big gene that makes a big enzyme that produces alpha-amanitin, since that’s how other fungi produce similar compounds. But after years of defeat, she and her team called in the big guns — new technology that sequences DNA about as fast as a death cap mushroom can kill. The results: The discovery of remarkably small genes that produce the toxin — a unique pathway previously unknown in fungi.

Brain Matures A Few Years Late In ADHD, But Follows Normal Pattern:

In youth with attention deficit hyperactivity disorder (ADHD), the brain matures in a normal pattern but is delayed three years in some regions, on average, compared to youth without the disorder, an imaging study by researchers at the National Institutes of Health’s (NIH) National Institute of Mental Health (NIMH) has revealed. The delay in ADHD was most prominent in regions at the front of the brain’s outer mantle (cortex), important for the ability to control thinking, attention and planning. Otherwise, both groups showed a similar back-to-front wave of brain maturation with different areas peaking in thickness at different times.

Tool-wielding Chimps Provide A Glimpse Of Early Human Behavior:

Chimpanzees inhabiting a harsh savanna environment and using bark and stick tools to exploit an underground food resource are giving scientists new insights to the behaviors of the earliest hominids who, millions of years ago, left the African forests to range the same kinds of environments and possibly utilize the same foods.

Tiny Fish Can Yield Big Clues To Delaware River Health:

Where have all the bridle shiner gone? That’s the mystery The Academy of Natural Sciences’ fish scientists are trying to answer, and the outcome will shed light on the environmental health of the Upper Delaware River.

Changing Environment Organizes Genetic Structure:

What is the fundamental creative force behind life on Earth? It’s a question that has vexed mankind for millennia, and thanks to theory and almost a year’s worth of number-crunching on a supercomputer, Rice University physicist and bioengineer Michael Deem thinks he has the answer: A changing environment may organize the structure of genetic information itself.

ECGC In Green Tea Is Powerful Medicine Against Severe Sepsis, Lab Study Suggests:

A major component of green tea could prove the perfect elixir for severe sepsis, an abnormal immune system response to a bacterial infection. In a new laboratory study, Haichao Wang, PhD, of The Feinstein Institute for Medical Research, and his colleagues have been studying the therapeutic powers of dozens of Chinese herbal compounds in reversing a fatal immune response that kills 225,000 Americans every year. They found that an ingredient in green tea rescued mice from lethal sepsis — and the findings could pave the way to clinical trials in patients.

How Global Is The Global Biodiversity Information Facility?:

Biologists and computer scientists have appealed for more information on the world’s biodiversity to be stored digitally so it may better be used to understand the impact of climate change on the Earth’s flora and fauna.

‘Time-sharing’ Tropical Birds Key To Evolutionary Mystery:

Whereas most birds are sole proprietors of their nests, some tropical species “time share” together – a discovery that helps clear up a 150-year-old evolutionary mystery, says Biology professor Vicki Friesen.

There are 27 brand-new articles, just uploaded on PLoS ONE. Here are a couple of titles that drew my immediate attention:
Maternal Enrichment during Pregnancy Accelerates Retinal Development of the Fetus:

Although much is known about the harmful effects parental stress has on offspring, little is understood about how enriching a mother’s environment affects fetal development. In this paper, the authors experiment on developing rat embryos and find that an enriched environment speeds up the development of the nervous system. The results suggest that development of the visual system is sensitive to environmental stimulation during prenatal life.

Prior Exposure to Uninfected Mosquitoes Enhances Mortality in Naturally-Transmitted West Nile Virus Infection:

West Nile Virus has the potential to cause serious disease in humans; the virus is spread by infected mosquitoes and typically infection either results in no symptoms or in mild feverish symptoms. In this study, Higgs and colleagues found that mice that had already been exposed to the saliva from uninfected mosquitoes were subsequently more likely to die upon being infected with West Nile Virus. These findings suggest that prior exposure to mosquito saliva could potentially result in a worse outcome from West Nile Virus infection.

Gene Expression in Human Hippocampus from Cocaine Abusers Identifies Genes which Regulate Extracellular Matrix Remodeling:

People who have abused drugs in the past find it hard to avoid relapse because they remember the euphoria linked to previous drug use. In order to see if past drug abuse is associated with molecular changes in the brain, the researchers here carried out microarray analysis of samples of the hippocampus from individuals addicted to cocaine, and from control individuals. The microarray data identifies a number of genes which are up- or down-regulated in response to cocaine exposure.

Incidence and Tracking of Escherichia coli O157:H7 in a Major Produce Production Region in California:

Fresh vegetables have become associated with outbreaks caused by Escherichia coli O157:H7 (EcO157). Between 1995-2006, 22 produce outbreaks were documented in the United States, with nearly half traced to lettuce or spinach grown in California. Outbreaks between 2002 and 2006 induced investigations of possible sources of pre-harvest contamination on implicated farms in the Salinas and San Juan valleys of California, and a survey of the Salinas watershed. EcO157 was isolated at least once from 15 of 22 different watershed sites over a 19 month period. The incidence of EcO157 increased significantly when heavy rain caused an increased flow rate in the rivers. Approximately 1000 EcO157 isolates obtained from cultures of>100 individual samples were typed using Multi-Locus Variable-number-tandem-repeat Analysis (MLVA) to assist in identifying potential fate and transport of EcO157 in this region. A subset of these environmental isolates were typed by Pulse Field Gel Electrophoresis (PFGE) in order to make comparisons with human clinical isolates associated with outbreak and sporadic illness. Recurrence of identical and closely related EcO157 strains from specific locations in the Salinas and San Juan valleys suggests that transport of the pathogen is usually restricted. In a preliminary study, EcO157 was detected in water at multiple locations in a low-flow creek only within 135 meters of a point source. However, possible transport up to 32 km was detected during periods of higher water flow associated with flooding. During the 2006 baby spinach outbreak investigation, transport was also detected where water was unlikely to be involved. These results indicate that contamination of the environment is a dynamic process involving multiple sources and methods of transport. Intensive studies of the sources, incidence, fate and transport of EcO157 near produce production are required to determine the mechanisms of pre-harvest contamination and potential risks for human illness.

Different Neurophysiological Mechanisms Underlying Word and Rule Extraction from Speech:

The initial process of identifying words from spoken language and the detection of more subtle regularities underlying their structure are mandatory processes for language acquisition. Little is known about the cognitive mechanisms that allow us to extract these two types of information and their specific time-course of acquisition following initial contact with a new language. We report time-related electrophysiological changes that occurred while participants learned an artificial language. These changes strongly correlated with the discovery of the structural rules embedded in the words. These changes were clearly different from those related to word learning and occurred during the first minutes of exposition. There is a functional distinction in the nature of the electrophysiological signals during acquisition: an increase in negativity (N400) in the central electrodes is related to word-learning and development of a frontal positivity (P2) is related to rule-learning. In addition, the results of an online implicit and a post-learning test indicate that, once the rules of the language have been acquired, new words following the rule are processed as words of the language. By contrast, new words violating the rule induce syntax-related electrophysiological responses when inserted online in the stream (an early frontal negativity followed by a late posterior positivity) and clear lexical effects when presented in isolation (N400 modulation). The present study provides direct evidence suggesting that the mechanisms to extract words and structural dependencies from continuous speech are functionally segregated. When these mechanisms are engaged, the electrophysiological marker associated with rule-learning appears very quickly, during the earliest phases of exposition to a new language.

As always, look around, read, rate, comment, annotate and send trackbacks…

As always on Monday nights, there are new articles published in PLoS Biology and PLoS Medicine. My picks:
Professional Uncertainty and Disempowerment Responding to Ethnic Diversity in Health Care: A Qualitative Study

In a qualitative study published this week in PLoS Medicine, Joe Kai and colleagues have identified opportunities to empower health professionals to respond more effectively to challenges in their work with patients from diverse ethnic communities. A related perspective showcases the challenges that physicians face in providing culturally appropriate care.

Omnidirectional Sensory and Motor Volumes in Electric Fish:

Most animals, including humans, have sensory and motor capabilities that are biased in the forward direction. The black ghost knifefish, a nocturnal, weakly electric fish from the Amazon, is an interesting exception to this general rule. We demonstrate that these fish have sensing and motor capabilities that are omnidirectional. By combining video analysis of prey capture trajectories with computational modeling of the fish’s electrosensory capabilities, we were able to quantify and compare the 3-D volumes for sensation and movement. We found that the volume in which prey are detected is similar in size to the volume needed by the fish to stop. We suggest that this coupling may arise from constraints that the animal faces when using self-generated energy to probe its environment. This is similar to the way in which the angular coverage and range of an automobile’s headlights are designed to match certain motion characteristics of the vehicle, such as its typical cruising speed, turning angle, and stopping distance. We suggest that the degree of overlap between sensory and movement volumes can provide insight into the types of control strategies that are best suited for guiding behavior.

Also read the related synopsis. Interestingly, electroreception is the only sensory modality studied so far which does not exhibit centrifugal control, i.e., there is no “tuning” by the central nervous system – it is always tuned the same. In other senses (including some weird ones, e.g., magnetoreception), the brain modulates the sensitivity of the sensory organ. In all those cases, one of those modulations is by the circadian clock. Thus, all the senses except electroreception are more or less sensitive depending on the time of day. I wonder about the other active senses, i.e., senses in which animal emits something into the environment and then senses how the environment responds to it (e.g., sonar in dolphins, ultrasonic emitions of bats, etc.) as I am not sure those were studied.

How Well Do Dogs See At Night?:

A lot better than we do, says Paul Miller, clinical professor of comparative ophthalmology at University of Wisconsin-Madison.

Why Quitting Smoking Is So Difficult:

New findings clarify the brain mechanisms that explain many aspects of dependency on nicotine, the addictive substance in tobacco. Among them: Individual differences in brain chemistry can have a profound effect on a person’s susceptibility to addiction, and smoking may predispose adolescents to mental disorders in adolescence and adulthood. In addition, researchers have identified a potential neural network that regulates the body’s craving response and have demonstrated how smoking may affect decision-making.

For Migrating Sparrows, Kids Have A Compass, But Adults Have The Map:

Even bird brains can get to know an entire continent — but it takes them a year of migration to do so, suggests a Princeton research team.

One In Five Young Britons Has Sex With Someone New While Abroad:

Around one in five young Britons has sex with a new partner while overseas, finds research published ahead of print in the journal Sexually Transmitted Infections.

How The Brain Sends Eyeballs Bouncing:

All vision, including reading this sentence, depends on a constant series of infinitesimal jumps by the eyeball that centers the retina on target objects–words or phrases in the case of reading. Such jumps, or saccades, are critical to vision because only the small central region of the retina, called the fovea, produces the clear image necessary for perception. Such saccades take place several times a second and are generated within a brain region known as the frontal eye field (FEF).

Why Teens Are Such Impulsive Risk-takers:

Teenagers and adults often don’t see eye to eye, and new brain research is now shedding light on some of the reasons why. Although adolescence is often characterized by increased independence and a desire for knowledge and exploration, it also is a time when brain changes can result in high-risk behaviors, addiction vulnerability, and mental illness, as different parts of the brain mature at different rates.

When To Have A Child? A New Approach To The Decision:

Women seeking to balance career, social life and family life in making the decision on when to have a child may benefit from applying formal decision-making science to this complex emotional choice.

Bug-Zapper: A Dose Of Radiation May Help Knock Out Malaria:

How are physicists helping an effort to eradicate malaria, the mosquito-borne disease that kills more than one million people every year” Researchers at the National Institute of Standards and Technology (NIST) used their expertise in radiation science to help a young company create weakened, harmless versions of the malaria-causing parasite. These parasites, in turn, are being used to create a new type of vaccine that shows promise of being more effective than current malaria vaccines.

Why Dinosaurs Had ‘Fowl’ Breath:

Scientists have discovered how dinosaurs used to breathe in what provides clues to how they evolved and how they might have lived.

Sexist Humor No Laughing Matter, Psychologist Says:

A research project led by a Western Carolina University psychology professor indicates that jokes about blondes and women drivers are not just harmless fun and games; instead, exposure to sexist humor can lead to toleration of hostile feelings and discrimination against women.

Recreational Cocaine Use May Impair Inhibitory Control:

The recreational use of cocaine has rapidly increased in many European countries over the past few years. One cause of this is the fall in the price of the drug on the street from 100 Euros for one gram (about 5 lines) in 2000 to 50 Euros in the Netherlands today. One line of cocaine is, thus, now as cheap as a tablet of ecstasy. This means cocaine is no longer considered an “elite” drug but is affordable for all, especially for recreational use. It is therefore likely that the recreational use of cocaine will become a public health issue in the next few years, which is already the case for the recreational use of ecstasy.

To Fight Disease, Animals — Like Plants — Can Tolerate Parasites:

Animals, like plants, can build tolerance to infections at a genetic level, and these findings could provide a better understanding of the epidemiology and evolution of infectious disease, according to evolutionary biologists.

Lack Of Critical Lubricant Causes Wear In Animal Joints:

Mice that don’t produce lubricin, a thin film of protein found in the cartilage of joints, showed early wear and higher friction in their joints, a new study led by Brown University researchers shows.

Evolution: When Are Genes ‘Adventurous’ And When Are They Conservative?:

Taking a chance on an experiment – this is one of the impulses that drive evolution. Living cells are, from this angle, great subjects for experimentation: Changes in one molecule can have all sorts of interesting consequences for many other molecules in the cell. Such experiments on genes and proteins have led the cell, and indeed all life, on a long and fascinating evolutionary journey.