Wednesday, September 29, 2010

Teasing About Weight Can Affect Pre-Teens Profoundly, Study Suggests

Schoolyard taunts of any type can potentially damage a child's sense of self-confidence. But a new study suggests that a particular kind of teasing -- about weight -- can have distinctive and significant effects on how pre-teens perceive their own bodies.

The research, among the first to specifically examine the impact of weight-based criticism on pre-adolescents, also hints that the practice can cause other health and emotional issues for its victims.

"We tend to think of adolescence as the time when kids become sensitive about their body image, but our findings suggest that the seeds of body dissatisfaction are actually being sown much earlier," said Timothy D. Nelson, assistant professor of psychology at the University of Nebraska-Lincoln and the study's lead author. "Criticism of weight, in particular, can contribute to issues that go beyond general problems with self-esteem."

For the study, Nelson and his colleagues surveyed hundreds of public school students whose average age was 10.8 years. They collected participants' heights and weights and calculated their Body Mass Index, then examined the relationships between weight-related criticism and children's perceptions of themselves.

Their results showed that overweight pre-teens who endured weight-based criticism tended to judge their bodies more harshly and were less satisfied with their body sizes than students who weren't teased about their weight.

The effects of weight-based teasing were significant even when researchers removed the effects of students' BMI from their analysis in an attempt to separate the relative contributions of physical reality and children's social interactions to their body perceptions, Nelson said.

Because children who develop such negative views of their bodies are at higher risk for internalizing problems, developing irregular eating behaviors and ongoing victimization, researchers said these results should be a signal for more early identification and intervention efforts at schools.

"In a way, weight-related criticism is one of the last socially acceptable forms of criticism," Nelson said. "There's often a sense that overweight people 'deserve' it, or that if they are continually prodded about their weight, they'll do something about it.

"In fact, our research suggests that this kind of criticism tends to increase the victim's body dissatisfaction, which has been shown to be a factor in poorer outcomes with pediatric weight management programs. It becomes something of a vicious cycle."

The study notes that children's views of their bodies are a complex interaction between physical reality and socially influenced perceptions. Peer criticism about weight is an important social factor that could affect how pre-adolescents interpret the physical reality of their bodies, Nelson said.

The findings, Nelson said, should be relevant to understanding the consequences of weight-related criticism and considering interventions with preadolescents who are frequent targets of the taunts.

"While weight-related criticism is identifiable, programs targeting it are limited," he said. "Early identification of children who are targets of frequent and chronic weight-based criticism may also be important in reducing it and its harmful effects."

Nelson authored the study, which appears in the Journal of Pediatric Psychology, with Chad D. Jensen and Ric G. Steele of the Clinical Child Psychology Program at the University of Kansas.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Nebraska-Lincoln, via EurekAlert!, a service of AAAS.

Courtesy: ScienceDaily

Monday, September 27, 2010

How Molecules Escape from Cell's Nucleus: Key Advance in Using Microscopy to Reveal Secrets of Living Cells


By constructing a microscope apparatus that achieves resolution never before possible in living cells, researchers at Albert Einstein College of Medicine of Yeshiva University have illuminated the molecular interactions that occur during one of the most important "trips" in all of biology: the journey of individual messenger Ribonucleic acid (RNA) molecules from the nucleus into the cytoplasm (the area between the nucleus and cell membrane) so that proteins can be made.

The results, published in the September 15 online edition of Nature, mark a major advance in the use of microscopes for scientific investigation (microscopy). The findings could lead to treatments for disorders such as myotonic dystrophy in which messenger RNA gets stuck inside the nucleus of cells.

Robert Singer, Ph.D., professor and co-chair of anatomy and structural biology, professor of cell biology and neuroscience and co-director of the Gruss-Lipper Biophotonics Center at Einstein, is the study's senior author. His co-author, David Grünwald, is at the Kavli Institute of Nanoscience at Delft University of Technology, The Netherlands. Prior to their work, the limit of microscopy resolution was 200 nanometers (billionths of a meter), meaning that molecules closer than that could not be distinguished as separate entities in living cells. In this paper, the researchers improved that resolution limit by 10 fold, successfully differentiating molecules only 20 nanometers apart.

Protein synthesis is arguably the most important of all cellular processes. The instructions for making proteins are encoded in the Deoxyribonucleic acid (DNA) of genes, which reside on chromosomes in the nucleus of a cell. In protein synthesis, DNA instructions of a gene are transcribed, or copied, onto messenger RNA; these molecules of messenger RNA must then travel out of the nucleus and into the cytoplasm, where amino acids are linked together to form the specified proteins.

Molecules shuttling between the nucleus and cytoplasm are known to pass through protein complexes called nuclear pores. After tagging messenger RNA molecules with a yellow fluorescent protein (which appears green in the accompanying image) and tagging the nuclear pore with a red fluorescent protein, the researchers used high-speed cameras to film messenger RNA molecules as they traveled across the pores. The Nature paper reveals the dynamic and surprising mechanism by which nuclear pores "translocate" messenger RNA molecules from the nucleus into the cytoplasm: this is the first time their pore transport has been seen in living cells in real time.

"Up until now, we'd really had no idea how messenger RNA travels through nuclear pores," said Dr. Singer. "Researchers intuitively thought that the squeezing of these molecules through a narrow channel such as the nuclear pore would be the slow part of the translocation process. But to our surprise, we observed that messenger RNA molecules pass rapidly through the nuclear pores, and that the slow events were docking on the nuclear side and then waiting for release into the cytoplasm."

More specifically, Dr. Singer found that single messenger RNA molecules arrive at the nuclear pore and wait for 80 milliseconds (80 thousandths of a second) to enter; they then pass through the pore breathtakingly fast -- in just 5 milliseconds; finally, the molecules wait on the other side of the pore for another 80 milliseconds before being released into the cytoplasm.

The waiting periods observed in this study, and the observation that 10 percent of messenger RNA molecules sit for seconds at nuclear pores without gaining entry, suggest that messenger RNA could be screened for quality at this point.

"Researchers have speculated that messenger RNA molecules that are defective in some way, perhaps because the genes they're derived from are mutated, may be inspected and destroyed before getting into the cytoplasm or a short time later, and the question has been, 'Where might that surveillance be happening?'," said Dr. Singer. "So we're wondering if those messenger RNA molecules that couldn't get through the nuclear pores were subjected to a quality control mechanism that didn't give them a clean bill of health for entry."

In previous research, Dr. Singer studied myotonic dystrophy, a severe inherited disorder marked by wasting of the muscles and caused by a mutation involving repeated DNA sequences of three nucleotides. Dr. Singer found that in the cells of people with myotonic dystrophy, messenger RNA gets stuck in the nucleus and can't enter the cytoplasm. "By understanding how messenger RNA exits the nucleus, we may be able to develop treatments for myotonic dystrophy and other disorders in which messenger RNA transport is blocked," he said.

The paper, "In Vivo Imaging of Labelled Endogenous β-actin mRNA during Nucleocytoplasmic Transport," was published in the September 15 online edition of Nature.

Journal Reference:

  1. David Grünwald, Robert H. Singer. In vivo imaging of labelled endogenous β-actin mRNA during nucleocytoplasmic transport. Nature, 2010; DOI: 10.1038/nature09438

Courtesy: ScienceDaily

Sunday, September 26, 2010

How HIV Resists AZT: Virus Hijacks a Common Molecule

Rutgers researchers have discovered how HIV-1, the virus that causes AIDS, resists AZT, a drug widely used to treat AIDS.

The scientists, who report their findings in Nature Structural & Molecular Biology, believe their discovery helps researchers understand how important anti-AIDS treatments can fail and could help AIDS researchers develop more effective treatment for the disease.

"What we've found is the detailed way in which the mutations act to promote the resistance," said author Eddy Arnold, Board of Governors Professor of Chemistry and Chemical Biology, and a resident faculty member of the Center for Advanced Biotechnology and Medicine. "Instead of blocking the actions of AZT, the virus actually removes it, and it does so by using ATP, one of the most common cellular molecules. This is an outstanding example of how sneaky HIV can be in thwarting the efficacy of therapeutic drugs."

AZT was once the only treatment for AIDS, and it remains an important treatment, particularly in preventing the transmission of the virus from infected mothers to their unborn children.

Researchers knew almost from the beginning that the virus developed resistance to AZT, and that this resistance had to do with mutations, but the way the mutations worked to resist the drug was mysterious.

AZT works by inhibiting an enzyme, reverse transcriptase, which HIV needs to produce DNA from RNA, and thus replicate itself. About 10 years ago, biochemical studies in several laboratories established that AZT-resistant HIV-1 reverse transcriptase uses adenosine triphosphate, or ATP, which moves energy around inside the cell, to remove the AZT. Arnold and his co-authors have used X-ray crystallography to describe in atomic detail how the AZT-resistance mutations allow reverse transcriptase to recruit ATP to remove the AZT.

Arnold's co-authors are Roger Jones, professor of chemistry and chemical biology at Rutgers; Xiongying Tu, Kalyan Das, Qianwei Han, Arthur D. Clark Jr., Yulia Frenkel and Stefan G. Serafianos, of the Center for Advanced Biotechnology and Medicine; and Stephen Hughes and Paul Boyer of the National Cancer Institute in Frederick, Md. The Center for Advanced Biotechnology and Medicine is a joint center of Rutgers University and the University of Medicine and Dentistry of New Jersey. The study was funded by the National Institutes of Health, by grants from both the National Institute of Allergy and Infectious Diseases (NIAID), and the National Institute of General Medical Sciences (NIGMS), both part of the National Institutes of Health.

Journal Reference:

  1. Xiongying Tu, Kalyan Das, Qianwei Han, Joseph D Bauman, Arthur D Clark, Xiaorong Hou, Yulia V Frenkel, Barbara L Gaffney, Roger A Jones, Paul L Boyer, Stephen H Hughes, Stefan G Sarafianos, Eddy Arnold. Structural basis of HIV-1 resistance to AZT by excision. Nature Structural & Molecular Biology, 2010; DOI: 10.1038/nsmb.1908

Courtesy: ScienceDaily

Friday, September 24, 2010

Overprotective Parents May Impact Heart Anxiety in Adults With Congenital Heart Conditions

Adults with congenital heart disease are more likely to suffer heart-focused anxiety -- a fear of heart-related symptoms and sensations -- if their parents were overprotective during their childhood and adolescence. Dr. Lephuong Ong from Orion Health Services in Vancouver, and colleagues from University Health Network and York University in Toronto, Canada, suggest that health care professionals could encourage greater independence for adolescents and adults with congenital heart disease to improve their psychosocial adjustment.

Dr. Ong's work is published online in Springer's International Journal of Behavioral Medicine.

Approximately one percent of all infants are born with congenital heart defects and over 90 percent of these children survive into adulthood, thanks to recent medical advances. As well as their medical condition, these patients face mental health issues including anxiety, neurocognitive deficits, body image concerns and difficulties with relationships. Research suggests that levels of parental protection are likely to be higher in children with congenital heart disease compared with healthy children.

Ong and team investigated the relationship between patient recollections of parental overprotection -- defined as intrusion, excessive contact, infantilization and prevention of independent behavior -- and heart-focused anxiety in adults with congenital heart disease. The researchers assessed heart defect severity, heart-focused anxiety and perceived parental overprotection during childhood for a sub-sample of 192 adults participating in the study.

Their analyses showed that levels of heart-focused anxiety rose as levels of parental overprotection increased. Disease severity was also linked to higher anxiety levels. Surprisingly, levels of parental overprotection did not vary with disease severity.

The authors conclude: "Adults with congenital heart disease, who report their parents as being overprotective, might have learned to form negative interpretations of their symptoms and use maladaptive coping behaviors, like avoidance and fearful responding, when experiencing cardiac symptoms or when faced with situations that trigger cardiac-related sensations. Clinicians could consider providing recommended activity guidelines for parents and their children to reduce limitations on activities that are deemed medically appropriate, to encourage independence among adolescents and young adults with congenital heart defects."

Journal Reference:

  1. Lephuong Ong, Robert P. Nolan, Jane Irvine, Adrienne H. Kovacs. Parental Overprotection and Heart-Focused Anxiety in Adults with Congenital Heart Disease. International Journal of Behavioral Medicine, 2010; DOI: 10.1007/s12529-010-9112-y

Courtesy: ScienceDaily

Wednesday, September 22, 2010

AIDS Virus Lineage Much Older Than Previously Thought


An ancestor of HIV that infects monkeys is thousands of years older than previously thought, suggesting that HIV, which causes AIDS, is not likely to stop killing humans anytime soon, finds a study by University of Arizona and Tulane University researchers.

The simian immunodeficiency virus, or SIV, is at least 32,000 to 75,000 years old, and likely much older, according to a genetic analysis of unique SIV strains found in monkeys on Bioko Island, a former peninsula that separated from mainland Africa after the Ice Age more than 10,000 years ago. The research, which appears in the Sept. 17 issue of the journal Science, calls into question previous DNA sequencing data that estimated the virus' age at only a few hundred years.

The study results have implications for HIV. SIV, unlike HIV, does not cause AIDS in most of its primate hosts. If it took thousands of years for SIV to evolve into a primarily non-lethal state, it would likely take a very long time for HIV to naturally follow the same trajectory.

"HIV is the odd man out because, by and large, all the other species of immunodeficiency viruses impose a much lower mortality on their host species," said Michael Worobey, a professor in the UA's department of ecology and evolutionary biology, who led the study in conjunction with virologist Preston Marx of Tulane University.

"So, if SIV entered the picture relatively recently as was previously thought, we would think it achieved a much lower virulence over a short timescale," Worobey said. "But our findings suggest the opposite. If HIV is going to evolve to lower virulence, it is unlikely to happen anytime soon."

The study also raises a question about the origin of HIV, which scientists believe evolved from SIV. If humans have been exposed to SIV-infected monkeys for thousands of years, why did the HIV epidemic only begin in the 20th century?

"Something happened in the 20th century to change this relatively benign monkey virus into something that was much more potent and could start the epidemic. We don't know what that flashpoint was, but there had to be one," Marx said.

Finding these virus strains trapped on Bioko Island settles a long-standing debate, Worobey said.

"It's like finding a fossilized piece of virus evolution," he said. "We now have this little island that is revealing clues about SIV, and it says, 'It's old.' Now we know that humans were almost certainly exposed to SIV for a long time, probably hundreds of thousands of years."

"Reconstructing the evolutionary past by comparing the genes of these viruses is like looking out onto the ocean," Worobey said. "You can see a long way, but you don't know what lies beyond the horizon. At some point in the past, you don't know what happened. There is a whole lot of ocean out there that you can't get at with the methods that we have been using in trying to tease apart the relationships among these pathogens."

According to Worobey, SIV was distributed across the African continent before Bioko Island separated from the continent about 10,000 years ago.

"When that happened, whatever viruses were circulating at the time became isolated from the virus populations on mainland Africa," he said.

Marx, a virologist at the Tulane National Primate Research Center, tested his theory that SIV had ancient origins by seeking out DNA samples from monkey populations that had been isolated for thousands of years.

His research team collected bush meat samples from Bioko Drills (Mandrillus leucophaeus). The scientists found four different strains of SIV that were highly genetically divergent from those found on the mainland. Worobey then compared DNA sequences of the viruses with the assumption that the island strains evolved in isolation for more than 10,000 years.

The computer modeling showed the rate of mutation to be much slower than previously thought, indicating that the virus is between 32,000 and 75,000 years old. These dates set a new minimum age for SIV, although it is likely to be even older, Marx said.

Worobey said the study has implications for a lot of rapidly evolving pathogens.

"Our methods are great to describe and predict the short-term changes of viruses like the flu or HIV, but we need to be skeptical of inferences in deep time. We found there is a big disconnect between the rapid evolution for which those pathogens are famous and the incredible degree of conservation we've found."

"Being able to study these viruses in an isolated setting is a unique opportunity," he added.

"As far as we know, there is no other place like Bioko Island," Worobey said. "Nowhere else could we do this kind of deep time calibration. Some of the primate species on Bioko only have a few hundred individuals left and might go extinct in the not-too-distant future. We might not have been able to do this research 10 or 20 years from now."

"Looking into the eyes of these animals and knowing they carry the progenitor of HIV in their bodies sends a shiver down my spine."

Funding for Worobey's participation in this research was provided by a grant from the David and Lucile Packard Foundation.


Journal Reference:

  1. Michael Worobey, Paul Telfer, Sandrine Souquière, Meredith Hunter, Clint A. Coleman, Michael J. Metzger, Patricia Reed, Maria Makuwa, Gail Hearn, Shaya Honarvar, Pierre Roques, Cristian Apetrei, Mirdad Kazanji, and Preston A. Marx. Island Biogeography Reveals the Deep History of SIV. Science, 17 September 2010: 1487 DOI: 10.1126/science.1193550
Courtesy: ScienceDaily

Monday, September 20, 2010

50-Million-Year-Old Snake Gets a CT Scan


Even some of the most advanced technology in medicine couldn't get Clarisse to give up all of her secrets. After all, she's protected them for more than 50 million years. Clarisse is a snake, found in the Fossil Butte region of Wyoming, perfectly fossilized in limestone and the only one of her kind known to be in existence. Palentologist Hussan Zaher came to Houston at the behest of the Museum of Natural Science to study her.

He brought the precious find to The Methodist Hospital and subjected her to a detailed CT (computerized tomography) scan in hopes of finding where Clarisse fits along the timeline of evolution.

"Most fossilized remains of snakes are individual pieces of bone," said Zaher. "This is unique because it's a complete snake, which gives us an opportunity to study her makeup and hopefully learn more about her."

CT scan technician Pam Mager conducted the scan on a 64-slice scanner that is capable of sending laser-guided X-rays through a target. "We can take almost 3,000 images in less than a minute," she explained, "and then we can use those images to construct a three-dimensional picture of the snake's bone structure."

Zaher, professor and curator of the collections of herpetology and paleontology at the Museu de Zoologia of the Universidade de São Paulo in Brazil, worked with the Museum of Natural Science in Houston to get Clarisse to Methodist for the scan. He believes Clarisse could be an evolutionary link between snakes who take a lot of small bites to eat their prey and snakes who swallow their prey whole.

The snake fossil was preserved in what is now limestone, and the entire chunk of rock was placed on the bed of the CT scanner. In less than a minute, the images were taken and assembled by computer into a three-dimensional image that could be rotated 360 degrees.

Taking a preliminary look at the images, Zaher said he saw no traces of limbs. "That places it higher up the evolutionary scale, but the snake is still very old," he said. For more than an hour, he and technician Mager studied the images, looking at tiny details of the snake's skull to find clues to how it may have eaten its prey.

Clarisse is the best preserved Caenozoic snake known in a U.S. scientific collection. According to preliminary analysis, this snake is believed to be closely related to Boavus indelmani, a booid snake described in the late 1930′s. Zaher and the Houston museum hoped that getting a look at the underside of this unique fossil, as well as the inside of bones like the skull would shed some light on the evolutionary history of the species, and its relationship to booid snakes (like pythons and boas).

"This is a very important step in studying this specimen ... I will be able to take away copies of the images for further investigation and I believe this will help us learn about this snake," Zaher said. "I cannot express my gratitude enough to (The Methodist Hospital) and the radiology services department here."

The snake is part of the collection at the Houston Museum of Natural Science.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Methodist Hospital, Houston.


Courtesy: ScienceDaily

Sunday, September 12, 2010

Novel Nanotechnology Collaboration Leads to Breakthrough in Cancer Research

One of the most difficult aspects of working at the nanoscale is actually seeing the object being worked on. Biological structures like viruses, which are smaller than the wavelength of light, are invisible to standard optical microscopes and difficult to capture in their native form with other imaging techniques.

A multidisciplinary research group at UCLA has now teamed up to not only visualize a virus but to use the results to adapt the virus so that it can deliver medication instead of disease.

In a paper published in the journal Science, Hongrong Liu, a UCLA postdoctoral researcher in microbiology, immunology and molecular genetics, and colleagues reveal an atomically accurate structure of the adenovirus that shows the interactions among its protein networks. The work provides critical structural information for researchers around the world attempting to modify the adenovirus for use in vaccine and gene-therapy treatments for cancer.

To modify a virus for gene therapy, researchers remove its disease-causing DNA, replace it with medications and use the virus shell, which has been optimized by millions of years of evolution, as a delivery vehicle.

Lily Wu, a UCLA professor of molecular and medical pharmacology and co-lead author of the study, and her group have been attempting to manipulate the adenovirus for use in gene therapy, but the lack of information about receptors on the virus's surface had hampered their quest.

"We are engineering viruses to deliver gene therapy for prostate and breast cancers, but previous microscopy techniques were unable to visualize the adapted viruses," Wu said. "This was like trying to a piece together the components of a car in the dark, where the only way to see if you did it correctly was to try and turn the car on."

To better visualize the virus, Wu sought assistance from Hong Zhou, a UCLA professor of microbiology, immunology and molecular genetics and the study's other lead author. Zhou uses cryo-electron microscopy (cryoEM) to produce atomically accurate three-dimensional models of biological samples such as viruses.

Wu, who is also a researcher at the California NanoSystems Institute (CNSI) at UCLA, learned of Zhou's work after he was jointly recruited to UCLA from the University of Texas Medical School at Houston by the UCLA Department of Microbiology, Immunology and Molecular Genetics and UCLA's CNSI.

About a year ago, once the transfer of Zhou's lab was complete, Sok Boon Koh, one of Wu's students, sought out Zhou's group for their expertise and initiated the collaboration.

"This project exemplifies my excitement about being part of an institute as innovative as CNSI," Zhou said. "Not only am I able to work with state-of-the-art equipment, but because CNSI is the hub for nanotechnology research and commercialization at UCLA, I have the opportunity to collaborate with colleagues across many disciplines."

Working in the Electron Imaging Center for Nanomachines at the CNSI, a lab run by Zhou, the researchers used cryoEM to create a 3-D reconstruction of the human adenovirus from 31,815 individual particle images.

"Because the reconstruction reveals details up to a resolution of 3.6 angstroms, we are able to build an atomic model of the entire virus, showing precisely how the viral proteins all fit together and interact," Zhou said. An angstrom is the distance between the two hydrogen atoms in a water molecule, and the entire adenovirus is about 920 angstroms in diameter.

Armed with this new understanding, Wu and her group are now moving forward with their engineered versions of adenovirus to use for gene therapy treatment of cancer.

"This breakthrough is a great leap forward, but there are still many obstacles to overcome," Wu said. "If our work is successful, this therapy could be used to treat most forms of cancer, but our initial efforts have focused on prostate and breast cancers because those are the two most common forms of cancer in men and women, respectively."

The group is working with the adenovirus because previous research has established it as a good candidate for gene therapy due to its efficiency in delivering genetic materials inside the body. The virus shell is also a safe delivery vehicle; tests have shown that the shell does not cause cancer, a problem encountered with some other virus shells. The adenovirus is relatively non-pathogenic naturally, causing only temporary respiratory illness in 5 to 10 percent of people.

CryoEM enables such a high-resolution reconstruction of biological structures because samples, in water, are imaged directly. In contrast, with X-ray crystallography (the conventional technique for atomic resolution models of biological structures), researchers grow crystal structures replicating the sample and then use diffraction to solve the crystal structure. This technique is limited because it is difficult to grow crystals for all proteins, samples for x-ray crystallography need to be very pure and uniform, and crystals of large complexes may not diffract to high resolution. These limitations resulted in critical areas of the adenovirus surface being unresolved using x-ray crystallography.

The study was funded by the National Cancer Institute and the U.S. Department of Defense.

Journal Reference:

  1. H. Liu, L. Jin, S. B. S. Koh, I. Atanasov, S. Schein, L. Wu, Z. H. Zhou. Atomic Structure of Human Adenovirus by Cryo-EM Reveals Interactions Among Protein Networks. Science, 2010; 329 (5995): 1038 DOI: 10.1126/science.1187433

Courtesy: ScienceDaily

Friday, September 10, 2010

Brainy Worms: Scientists Uncover Counterpart of Cerebral Cortex in Marine Worms

Our cerebral cortex, or pallium, is a big part of what makes us human: art, literature and science would not exist had this most fascinating part of our brain not emerged in some less intelligent ancestor in prehistoric times. But when did this occur and what were these ancestors? Unexpectedly, scientists at the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, have now discovered a true counterpart of the cerebral cortex in an invertebrate, a marine worm.

Their findings are published in Cell, and give an idea of what the most ancient higher brain centres looked like, and what our distant ancestors used them for.

It has long been clear that, in evolutionary terms, we share our pallium with other vertebrates, but beyond that was mystery. This is because even invertebrates that are clearly related to us -- such as the fish-like amphioxus -- appear to have no similar brain structures, nothing that points to a shared evolutionary past. But EMBL scientists have now found brain structures related to the vertebrate pallium in a very distant cousin -- the marine ragworm Platynereis dumerilii, a relative of the earthworm -- which last shared an ancestor with us around 600 million years ago.

"Two stunning conclusions emerge from this finding," explains Detlev Arendt, who headed the study: "First, the pallium is much older than anyone would have assumed, probably as old as higher animals themselves. Second, we learn that it came out of 'the blue' -- as an adaptation to early marine life in Precambrian oceans."

To uncover the evolutionary origins of our brain, EMBL scientist Raju Tomer, who designed and conducted the work, took an unprecedentedly deep look at the regions of Platynereis dumerilii's brain responsible for processing olfactory information -- the mushroom-bodies. He developed a new technique, called cellular profiling by image registration (PrImR), which is the first to enable scientists to investigate a large number of genes in a compact brain and determine which are turned on simultaneously. This technique enabled Tomer to determine each cell's molecular fingerprint, defining cell types according to the genes they express, rather than just based on their shape and location as was done before.

"Comparing the molecular fingerprints of the developing ragworms' mushroom-bodies to existing information on the vertebrate pallium," Arendt says, " it became clear that they are too similar to be of independent origin and must share a common evolutionary precursor."

This ancestral structure was likely a group of densely packed cells, which received and processed information about smell and directly controlled locomotion. It may have enabled our ancestors crawling over the sea floor to identify food sources, move towards them, and integrate previous experiences into some sort of learning.

"Most people thought that invertebrate mushroom-bodies and vertebrate pallium had arisen independently during the course of evolution, but we have proven this was most probably not the case," says Tomer. Arendt concludes: "The evolutionary history of our cerebral cortex has to be rewritten."

Journal Reference:

  1. Raju Tomer, Alexandru S. Denes, Kristin Tessmar-Raible, Detlev Arendt. Profiling by Image Registration Reveals Common Origin of Annelid Mushroom Bodies and Vertebrate Pallium. Cell, 2010; 142 (5): 800-809 DOI: 10.1016/j.cell.2010.07.043

Courtesy: ScienceDaily

Wednesday, September 8, 2010

Edible Nanostructures: Compounds Made from Renewable Materials Could Be Used for Gas Storage, Food Technologies

Sugar, salt, alcohol and a little serendipity led a Northwestern University research team to discover a new class of nanostructures that could be used for gas storage and food and medical technologies. And the compounds are edible.

The porous crystals are the first known all-natural metal-organic frameworks (MOFs) that are simple to make. Most other MOFs are made from petroleum-based ingredients, but the Northwestern MOFs you can pop into your mouth and eat, and the researchers have.

"They taste kind of bitter, like a Saltine cracker, starchy and bland," said Ronald A. Smaldone, a postdoctoral fellow at Northwestern. "But the beauty is that all the starting materials are nontoxic, biorenewable and widely available, offering a green approach to storing hydrogen to power vehicles."

Smaldone is co-first author of a paper about the edible MOFs published by Angewandte Chemie. The study is slated to appear on the cover of one of the journal's November issues.

"With our accidental discovery, chemistry in the kitchen has taken on a whole new meaning," said Sir Fraser Stoddart, Board of Trustees Professor of Chemistry in the Weinberg College of Arts and Sciences at Northwestern. The implications of what Sir Fraser refers to as "Bob's your uncle chemistry" go all the way from cleaner air to healthier living, and it all comes from a product that can be washed down the sink.

Stoddart led the research group that included a trio of postdoctoral fellows in chemistry at Northwestern and colleagues from the University of California, Los Angeles (UCLA) and the University of St. Andrews in the U.K.

Metal-organic frameworks are well-ordered, lattice-like crystals. The nodes of the lattices are metals (such as copper, zinc, nickel or cobalt), and organic molecules connect the nodes. Within their very roomy pores, MOFs can effectively store gases such as hydrogen or carbon dioxide, making the nanostructures of special interest to engineers as well as scientists.

"Using natural products as building blocks provides a new direction for an old technology," said Jeremiah J. Gassensmith, a postdoctoral fellow in Stoddart's lab and an author of the paper.

"The metal-organic framework technology has been around since 1999 and relies on chemicals that come from crude oil," explained Ross S. Forgan, also a postdoctoral fellow in Stoddart's lab and co-first author of the paper. "Our main constituent is a starch molecule that is a leftover from corn production."

For their edible MOFs, the researchers use not ordinary table sugar but gamma-cyclodextrin, an eight-membered sugar ring produced from biorenewable cornstarch. The salts can be potassium chloride, a common salt substitute, or potassium benzoate, a commercial food preservative, and the alcohol is the grain spirit Everclear.

With these ingredients in hand, the researchers actually had set out to make new molecular architectures based on gamma-cyclodextrin. Their work produced crystals. Upon examining the crystals' structures using X-rays, the researchers were surprised to discover they had created metal-organic frameworks -- not an easy feat using natural products.

"Symmetry is very important in metal-organic frameworks," Stoddart said. "The problem is that natural building blocks are generally not symmetrical, which seems to prevent them from crystallizing as highly ordered, porous frameworks."

It turns out gamma-cyclodextrin solves the problem: it comprises eight asymmetrical glucose residues arranged in a ring, which is itself symmetrical. The gamma-cyclodextrin and potassium salt are dissolved in water and then crystallized by vapor diffusion with alcohol.

The resulting arrangement -- crystals consisting of cubes made from six gamma-cyclodextrin molecules linked in three-dimensions by potassium ions -- was previously unknown. The research team believes this strategy of marrying symmetry with asymmetry will carry over to other materials.

The cubes form a porous framework with easily accessible pores, perfect for capturing gases and small molecules. The pore volume encompasses 54 percent of the solid body.

"We achieved this level of porosity quickly and using simple ingredients," Smaldone said. "Creating metal-organic frameworks using petroleum-based materials, on the other hand, can be expensive and very time consuming."

Stoddart added, "It is both uplifting and humbling to come to terms with the fact that a piece of serendipity could have far-reaching consequences for energy storage and environmental remediation on the one hand and food quality control and health care on the other."

The National Science Foundation and the Engineering and Physical Sciences Research Council (U.K.) supported the research.

Journal Reference:

  1. Smaldone et al. Metal-Organic Frameworks from Edible Natural Products. Angewandte Chemie International Edition, 2010; DOI: 10.1002/anie.201002343

Courtesy: ScienceDaily

Monday, September 6, 2010

Ants Take on Goliath Role in Protecting Trees in the Savanna from Elephants

Ants are not out of their weight class when defending trees from the appetite of nature's heavyweight, the African elephant, a new University of Florida study finds.

Columns of angered ants will crawl up into elephant trunks to repel the ravenous beasts from devouring tree cover throughout drought-plagued East African savannas, playing a potentially important role in regulating carbon sequestration in these ecosystems, said Todd Palmer, a UF biology professor and co-author of a paper being published in the journal Current Biology.

"It really is a David and Goliath story, where these little ants are up against these huge herbivores, protecting trees and having a major impact on the ecosystems in which they live," Palmer said. "Swarming groups of ants that weigh about 5 milligrams each can and do protect trees from animals that are about a billion times more massive."

The mixture of trees and grasses that make up savanna ecosystems are traditionally thought to be regulated by rainfall, soil nutrients, plant-eating herbivores and fire, he said.

"Our results suggest that plant defense should be added to the list," he said. "These ants play a central role in preventing animals that want to eat trees from doing extensive damage to those trees."

While conducting research in the central highlands of Kenya, where hungry elephants have destroyed much of the tree cover, Palmer said he and his colleague and former UF post-doctoral student, Jacob Goheen, now a University of Wyoming zoology, physiology and botany professor, noticed that elephants rarely ate a widespread tree species known as Acacia drepanolobium where guardian ants aggressively swarm anything that touches the trees. But they would feed on other trees that did not harbor these ants.

The researchers decided to test whether these tiny ants were repelling the world's largest land mammal by serving as bodyguards for the tree in exchange for shelter and the food it supplied in the form of a sugary nectar solution. So they offered elephants at a wildlife orphanage a choice between these "ant plant" trees, with and without ants on the branches, and their favorite species of tree, the Acacia mellifera, to which the researchers added ants to some of its otherwise antless branches.

"We found the elephants like to eat the "ant plant" trees just as much as they like to eat their favorite tree species, and that when either tree species had ants on them, the elephants avoided those trees like a kid avoids broccoli," he Palmer said.

Also, the researchers removed ants from "ant trees" out in the field to see if elephants would attack them undefended, and a year later found much more damage than on trees with ants. Satellite images between 2003 and 2008 confirmed the ants were having a widespread, long-term effect throughout the savanna, he said.

The ants did not seem to annoy tree-feeding giraffes, who used their long tongues to swipe away them away from their short snouts, in marked contrast to the long nose or trunk on an elephant, Palmer said. The inside of an elephant's trunk is tender and highly sensitive to thousands of biting ants swarming up into it, he said.

"An elephant's trunk is a truly remarkable organ, but also appears to be their Achille's heel when it comes to squaring off with an angry ant colony," he said.

Because it appears that smell alerts elephants to avoid trees that are occupied by ants, it raises the question of whether ant odors might be applied to crops to deter elephants from feeding on them, just as DEET helps repel mosquitoes from people, he said.

"A big issue in east Africa is elephants damaging crops, which is one reason elephants have been harassed and sometimes killed," he said. "There's been a lot of interest in the conservation world about how to minimize the conflict elephants have with humans and particularly how to keep elephants from raiding agricultural fields."

One predicted outcome of global warming is more frequent and intense droughts, which will force desperate elephants to eat everything they can to survive, Palmer said "With more droughts, the extent to which elephants destroy and remove trees may increase and potentially shift the ecosystems back to grasslands," he said.

Ants' role in saving trees is critical with the interest in slowing the accumulation of greenhouse gasses since trees absorb carbon dioxide from the atmosphere, Palmer said.

"These 'ant plants' don't cover just a few hundred acres but are distributed throughout east Africa from southern Sudan all the way over to eastern Zaire and down through the horn of Africa and Tanzania," he said. "So they potentially play a big role in terms of regulating carbon dynamics in these ecosystems."

Journal Reference:

  1. Jacob R. Goheen, and Todd M. Palmer. Defensive Plant-Ants Stabilize Megaherbivore-Driven Landscape Change in an African Savanna. Current Biology, 2010; DOI: 10.1016/j.cub.2010.08.015

Courtesy: ScienceDaily

Saturday, September 4, 2010

Children Raised by Gay Couples Show Good Progress Through School, Study Finds

In nearly every discussion, debate or lawsuit about gay marriage, the talk at some point turns to family values.

Do gay couples make for good parents? Will their children -- whether adopted, conceived with the help of a surrogate or brought in from a pre-existing relationship -- adjust, adapt and succeed in a world dominated by traditional families?

The answers usually depend on who's giving them, and come dressed in anecdotes and colored by bias. But Stanford sociologist Michael Rosenfeld brings something new to the conversation: facts and figures derived from the country's largest data bank -- the U.S. Census.

In a study published this month in the journal Demography, Rosenfeld concludes that children being raised by same-sex couples have nearly the same educational achievement as children raised by married heterosexual couples.

By mining data from the 2000 Census, Rosenfeld was able to figure out the rates at which children in all types of families repeated a grade during elementary or middle school. According to his findings, nearly 7 percent of children raised by heterosexual married couples were held back a year, while about 9.5 percent of children living with adults identifying themselves as same-sex partners repeated a grade.

The difference between the groups pretty much vanishes when taking into account that the heterosexual couples were slightly more educated and wealthier than most gay parents, Rosenfeld said.

"The census data show that having parents who are the same gender is not in itself any disadvantage to children," he said. "Parents' income and education are the biggest indicators of a child's success. Family structure is a minor determinant."

Rosenfeld's findings have been cited by lawyers fighting Proposition 8, the gay marriage ban passed by California voters in 2008. A federal court judge recently overturned the ban, but his ruling is under appeal.

Rosenfeld's study shows that children of gay and married couples had lower grade-repetition rates than their peers raised by opposite-sex unmarried couples and single parents. And all children living in some type of family environment did much better than those living in group housing. Those who were awaiting adoption or placement in a foster home were held back about 34 percent of the time.

"One of the fundamental issues in modern family law that differs from state to state is whether same-sex couples can adopt," Rosenfeld said. "My research makes clear that there's a huge advantage to kids to be out of the care of the state and into the care of any family, even if the family is not perfectly optimal."

Educators, policymakers and social scientists have long known that children left back in school are at greater risk than their peers for not finishing high school and getting into trouble.

Because gays and lesbians make up such a tiny sliver of the American population -- only 1 percent -- it has been difficult for researchers to conduct a representative study of how their children perform in the classroom. And gay marriage opponents have criticized earlier studies for having sample sizes that are too small.

"Sample size is power," Rosenfeld said. "And the census is the biggest sample we have. This study is based on a sample of thousands and thousands of kids."

Most personal decisions about gay marriage are based on gut feelings, religious beliefs and individual experiences. Rosenfeld knows his research isn't going to change the minds of most people opposed to same-sex unions. But he has added new data to the debate that helps debunk assertions -- whether based on a lack of knowledge or some unfounded fear -- that children raised by gay couples cannot thrive.

"Social scientists have an obligation to shed light where they can on issues that are roiling the public," he said. "Sometimes we have to throw up our hands and admit that something is unknowable. But in this case, we could bring some real hard data to bear on an area that was otherwise really in the dark."

Journal Reference:

  1. Michael J. Rosenfeld. Nontraditional Families and Childhood Progress Through School. Demography, 2010; 47 (3): 755 DOI: 10.1353/dem.0.0112
Courtesy: ScienceDaily

Thursday, September 2, 2010

Diverse Diet of Veggies May Decrease Lung Cancer Risk

Adding a variety of vegetables to one's diet may help decrease the chance of getting lung cancer, and adding a variety of fruits and vegetables may decrease the risk of squamous cell lung cancer, especially among smokers.

Study results are published in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.

"Although quitting smoking is the most important preventive action in reducing lung cancer risk, consuming a mix of different types of fruit and vegetables may also reduce risk, independent of the amount, especially among smokers," said H. Bas Bueno-de-Mesquita, M.D., M.P.H., Ph.D., senior scientist and project director of cancer epidemiology at The National Institute for Public Health and the Environment, The Netherlands.

Using information from the ongoing, multi-centered European Prospective Investigation into Cancer and Nutrition (EPIC) study, Bueno-de-Mesquita and colleagues evaluated 452,187 participants with complete information, 1,613 of whom were diagnosed with lung cancer.

Information was obtained on 14 commonly eaten fruits and 26 commonly eaten vegetables. The fruits and vegetables evaluated in the EPIC study consisted of a wide variety of fresh, canned or dried products.

Previous results from the EPIC study showed that the quantity of vegetables and fruits may decrease risk of lung cancer; in particular the risk of one specific type of lung cancer, squamous cell carcinoma, decreased in current smokers.

Regardless of the amount, the researchers on the current study found that risk of lung cancer also decreased when a variety of vegetables were consumed. In addition, the risk of squamous cell carcinoma decreased substantially when a variety of fruits and vegetables were eaten. However, Bueno-de-Mesquita said that they "cannot exclude that these results can still be explained by smoking."

"Fruits and vegetables contain many different bioactive compounds, and it makes sense to assume that it is important that you not only eat the recommended amounts, but also consume a rich mix of these bioactive compounds by consuming a large variety," he said.

While previous research has shown the influence of the quantity of fruits and vegetables on cancer development, Stephen Hecht, Ph.D., editorial board member for Cancer Epidemiology, Biomarkers & Prevention, believes this study is one of the first to evaluate diversity of fruit and vegetable consumption, rather than quantity.

"The results are very interesting and demonstrate a protective effect in smokers. There are still over a billion smokers in the world, and many are addicted to nicotine and cannot stop in spite of their best efforts," added Hecht, who is the Wallin Land Grant Professor of Cancer Prevention at the Masonic Cancer Center, University of Minnesota.

Tobacco smoke contains a complex mixture of cancer causing agents. Therefore, a mixture of protective agents is needed to have any beneficial effect in reducing one's chance of lung cancer, Hecht said.

"Nevertheless, the public should be made aware and be reminded that the only proven way to reduce your risk for lung cancer is to avoid tobacco in all its forms," he said.


Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Association for Cancer Research.

Courtesy: ScienceDaily

Wednesday, September 1, 2010

Scientists Succeed in Filming Organs and Joints in Real Time Using Magnetic Resonance Imaging

"Please hold absolutely still": This instruction is crucial for patients being examined by magnetic resonance imaging (MRI). It is the only way to obtain clear images for diagnosis. Up to now, it was therefore almost impossible to image moving organs using MRI.

Max Planck researchers from Göttingen have now succeeded in significantly reducing the time required for recording images -- to just one fiftieth of a second. With this breakthrough, the dynamics of organs and joints can be filmed "live" for the first time: movements of the eye and jaw as well as the bending knee and the beating heart. The new MRI method promises to add important information about diseases of the joints and the heart. In many cases MRI examinations may become easier and more comfortable for patients.

A process that required several minutes until well into the 1980s, now only takes a matter of seconds: the recording of cross-sectional images of our body by magnetic resonance imaging (MRI). This was enabled by the FLASH (fast low angle shot) method developed by Göttingen scientists Jens Frahm and Axel Haase at the Max Planck Institute for Biophysical Chemistry. FLASH revolutionised MRI and was largely responsible for its establishment as a most important modality in diagnostic imaging. MRI is completely painless and, moreover, extremely safe. Because the technique works with magnetic fields and radio waves, patients are not subjected to any radiation exposure as is the case with X-rays. At present, however, the procedure is still too slow for the examination of rapidly moving organs and joints. For example, to trace the movement of the heart, the measurements must be synchronised with the electrocardiogram (ECG) while the patient holds the breath. Afterwards, the data from different heart beats have to be combined into a film.

Future prospect: extended diagnostics for diseases

The researchers working with Jens Frahm, Head of the non-profit "Biomedizinische NMR Forschungs GmbH," now succeeded in further accelerating the image acquisition process. The new MRI method developed by Jens Frahm, Martin Uecker and Shuo Zhang reduces the image acquisition time to one fiftieth of a second (20 milliseconds), making it possible to obtain "live recordings" of moving joints and organs at so far inaccessible temporal resolution and without artefacts. Filming the dynamics of the jaw during opening and closing of the mouth is just as easy as filming the movements involved in speech production or the rapid beating of the heart. "A real-time film of the heart enables us to directly monitor the pumping of the heart muscle and the resulting blood flow -- heartbeat by heartbeat and without the patient having to hold the breath," explains Frahm.

The scientists believe that the new method could help to improve the diagnosis of conditions such as coronary heart disease and myocardial insufficiency. Another application involves minimally invasive interventions which, thanks to this discovery, could be carried out in future using MRI instead of X-rays. "However, as it was the case with FLASH, we must first learn how to use the real-time MRI possibilities for medical purposes," says Frahm. "New challenges therefore also arise for doctors. The technical progress will have to be 'translated' into clinical protocols that provide optimum responses to the relevant medical questions."

Less is more: acceleration through better image reconstruction

To achieve the breakthrough to MRI measurement times that only take very small fractions of a second, several developments had to be successfully combined with each other. Whilst still relying on the FLASH technique, the scientists used a radial encoding of the spatial information which renders the images insensitive to movements. Mathematics was then required to further reduce the acquisition times. "Considerably fewer data are recorded than are usually necessary for the calculation of an image. We developed a new mathematical reconstruction technique which enables us to calculate a meaningful image from data which are, in fact, incomplete," explains Frahm. In the most extreme case it is possible to calculate an image of comparative quality out of just five percent of the data required for a normal image -- which corresponds to a reduction of the measurement time by a factor of 20. As a result, the Göttingen scientists have accelerated MRI from the mid 1980s by a factor of 10000.

Although these fast MRI measurements can be easily implemented on today's MRI devices, something of a bottleneck exists when it comes to the availability of sufficiently powerful computers for image reconstruction. Physicist Martin Uecker explains: "The computational effort required is gigantic. For example, if we examine the heart for only a minute in real time, between 2000 and 3000 images arise from a data volume of two gigabytes." Uecker consequently designed the mathematical process in such a way that it is divided into steps that can be calculated in parallel. These complex calculations are carried out using fast graphical processing units that were originally developed for computer games and three-dimensional visualization. "Our computer system requires about 30 minutes at present to process one minute's worth of film," says Uecker. Therefore, it will take a while until MRI systems are equipped with computers that will enable the immediate calculation and live presentation of the images during the scan.

In order to minimise the time their innovation will take to reach practical application, the Göttingen researchers are working in close cooperation with the company Siemens Healthcare.

Video of beating heart.

Journal Reference:

  1. Martin Uecker, Shuo Zhang, Dirk Voit, Alexander Karaus, Klaus-Dietmar Merboldt, Jens Frahm. Real-time MRI at a resolution of 20 ms. NMR in Biomedicine, 2010; DOI: 10.1002/nbm.1585

Courtesy: ScienceDaily