sid_melo blogreen

domingo, 25 de maio de 2014

Personal judgments swayed by group opinion, but only for three days

We all want to feel like we're free-thinking individuals, but there's nothing like the power of social pressure to sway an opinion. New research suggests that people do change their own personal judgments so that they fall in line with the group norm, but the change only seems to last about 3 days. The research is published in Psychological Science, a journal of the Association for Psychological Science.

"Our findings suggest that exposure to others' opinions does indeed change our own private opinions -- but it doesn't change them forever," says psychological scientist and study author Rongjun Yu of South China Normal University. "Just like working memory can hold about 7 items and a drug can be effective for certain amount of time, social influence seems to have a limited time window for effectiveness."

The fact that personal judgments are swayed by the opinions' of others is a well-established phenomenon in psychology research.

But it's unclear whether oft-observed social conformity reflects public compliance, motivated by a desire to fit in with the group and avoid social rejection, or private acceptance, which leads to a genuine change in personal opinion that persists even when social influence is removed.

Yu and colleagues Yi Huang and Keith Kendrick decided to investigate this question in the lab. They recruited Chinese college students to participate in a study exploring how "people perceive facial attractiveness." The students looked at 280 digital photographs of young adult Chinese women and were asked to rate the attractiveness of each face on an 8-point scale.

After rating a face, they saw the purported average of 200 other students' ratings for that face. Importantly, the group average matched the participant's rating only 25% of the time. The rest of the time, the group average fell 1, 2, or 3 points above or below the participant's rating.

The students were brought back to the lab to rate the faces again after either 1 day, 3 days, 7 days, or 3 months has passed.

The data showed that the group norm seemed to sway participant's own judgments when they re-rated the photos 1 and 3 days after the initial session.

There was, however, no evidence for a social-conformity effect when the intervening period was longer (either 7 days or 3 months after the first session).

According to the researchers, the fact that participants' opinions were swayed for up to 3 days suggests more than a superficial lab-based effect -- rather, group norms seem to have had a genuine, albeit brief, impact on participants' privately held opinions.

These studies are notable, says Yu, because they were able to control for methodological issues that often arise in studies that use a test-retest format, such as the natural human tendencies to regress to the mean and to behave consistently over time.

The one question that Yu and colleagues still don't know the answer to is why the effect lasts for 3 days. They plan on investigating whether there might be a neurological reason for the duration of the effect, and whether the effect can be manipulated to last for shorter or longer durations.

Story Source:

The above story is based on materials provided by Association for Psychological Science. Note: Materials may be edited for content and length.

Journal Reference:

Y. Huang, K. M. Kendrick, R. Yu. Conformity to the Opinions of Other People Lasts for No More Than 3 Days. Psychological Science, 2014; DOI: 10.1177/0956797614532104

How Alzheimer's blood test could be first step in developing treatments to halt or slow disease

May 23 / 2014

American Association for Clinical Chemistry (AACC)

A blood test has the potential to predict Alzheimer’s disease before patients start showing symptoms, researchers have reported. Now they expand upon this groundbreaking research and discuss why it could be the key to curing this devastating illness. "This discovery is a potentially enormous breakthrough in the fight against Alzheimer's," said an expert. "If research aimed at a cure for Alzheimer's is to move forward, it is crucial that Alzheimer's clinical trials find a way to recruit patients who are still asymptomatic, since they are the ones most likely to respond to treatment."

In March of this year, a team of Georgetown University scientists published research showing that, for the first time ever, a blood test has the potential to predict Alzheimer's disease before patients start showing symptoms. AACC is pleased to announce that a late-breaking session at the 2014 AACC Annual Meeting & Clinical Lab Expo in Chicago will expand upon this groundbreaking research and discuss why it could be the key to curing this devastating illness.

According to the World Health Organization, the number of Alzheimer's patients worldwide is expected to skyrocket from the 35.6 million individuals who lived with it in 2010 to 115.4 million by 2050. Currently, however, all efforts to cure or effectively treat the disease have failed. Experts believe one explanation for this lack of success could be that the window of opportunity for treating Alzheimer's has already closed by the time its symptoms manifest.

Enter the research team led by Howard Federoff, MD, PhD, executive dean at Georgetown University School of Medicine in Washington, D.C. In cognitively healthy adults age 70 and older, Federoff's team measured the levels of 10 lipids found in the blood to identify, with 90% accuracy, which study group participants would develop cognitive impairment over a 2-3 year period. If this 10-lipid test is validated in larger studies, it could help researchers to develop treatments for Alzheimer's that halt or slow the disease before it even begins. A blood test would also be easier to perform than current Alzheimer's tests that use brain imaging or hard-to-collect cerebrospinal fluid, meaning that the Federoff team's test could be used for population-wide Alzheimer's screening.

Amrita Cheema, PhD, one of the main investigators on Federoff's team, will give an in-depth lecture on the test's significance, the science behind it, and the research techniques used to develop it in the July 28 AACC session, "Lipidomics: A Powerful Approach to Identify Pre-clinical Memory Impairment in Older Adults." Cheema is an associate professor and co-director of the Proteomics and Metabolomics Shared Resource at Georgetown University.

"This discovery is a potentially enormous breakthrough in the fight against Alzheimer's," said AACC CEO Janet B. Kreizman. "If research aimed at a cure for Alzheimer's is to move forward, it is crucial that Alzheimer's clinical trials find a way to recruit patients who are still asymptomatic, since they are the ones most likely to respond to treatment. The Federoff team's test could be the answer to this problem, and it also demonstrates how laboratory medicine helps patients achieve better health -- by not only ensuring that patients receive timely and appropriate treatment, but also by enabling researchers to develop effective treatments in the first place."

Story Source:

The above story is based on materials provided by American Association for Clinical Chemistry (AACC). Note: Materials may be edited for content and length.

Active genes in neurons profiled based on connections

Click to enlarge

The team tested their profiling technique on midbrain mouse neurons (blue) that use the neurotransmitter dopamine to send signals to a brain region known as the nucleus accumbens. To do so, they tagged protein-assembling ribosomes (red) using a small antibody that bound a fluorescent protein (green).

When it comes to the brain, wiring isn't everything. Although neurobiologists often talk in electrical metaphors, the reality is that the brain is not nearly as simple as a series of wires and circuits. Unlike their copper counterparts, neurons can behave differently depending on the situation.

Researchers in Jeffrey Friedman's Laboratory of Molecular Genetics have devised a way to create snapshots of gene expression in neurons based on their connections. These snapshots contain exhaustive lists of the active genes within neurons that send information to a synapse, the junction between neurons.

Their new technique, called Retro-TRAP, merges two approaches to understanding the brain: mapping all of its connections and profiling gene expression within populations of neurons, Friedman says. "We hope that Retro-TRAP will be broadly used and provide a more granular understanding of how complex neural circuits function and ultimately lead to better treatments for neurological and neuropsychiatric disorders."

"Refinements in neuroscience over time have allowed us to explore how the nervous system works in ever-greater detail, and the approach we have developed continues this trend," says Mats Ekstrand, a research associate in the laboratory. "By building on existing techniques, we are now able to take a closer look at the types of cells involved in a particular circuit and what they are doing."

In the long run, these sorts of insights might help explain why some diseases, such as Parkinson's Disease, afflict particular sets of neurons, or someday make it possible to precisely target treatments at a dysfunctional neural circuit, rather than bathing the entire brain in drug.

The researchers modified a technique known as translating ribosome affinity purification (TRAP), developed at Rockefeller by Nathaniel Heintz, Paul Greengard and others to identify gene expression using green fluorescent protein to tag protein-assembling machines called ribosomes.

In research published in Cell, Ekstrand, graduate student Alexander Nectow and colleagues describe how they used Retro-TRAP to introduce green fluorescent protein to the neuron via a virus that travels backwards from a synapse into the body of a mouse neuron. The researchers used a small antibody to link the ribosome with the fluorescent protein. Then, using these fluorescent tags, the researchers pulled out the ribosomes and sequenced the genetic messages passing through them. In this way, they produced a list of active genes.

To test their technique, the team focused on inputs to a well-studied part of the brain, the nucleus accumbens, which integrates information from throughout the brain, including regions involved in executive function, memory, depression, reward-related behavior, feeding and other functions, Nectow says.

"We wanted to target a selected number of inputs into the nucleus accumbens because we figured we might be able to get some molecular clues as to why it is important in regulating so many functions," Nectow says.

Using Retro-TRAP, they created molecular profiles of neurons extending from the hypothalamus and ventral midbrain that project to the nucleus accumbens. The results confirmed that Retro-TRAP works.

"The nucleus accumbens receives a lot of signals from the ventral midbrain via the neurotransmitter dopamine, and, as expected, the genes we sequenced included many associated with dopamine neurons," Nectow says.

Their data also contained some new discoveries. For instance, they found some neurons in the lateral hypothalamus express the p11 gene implicated in depression. After some further work, they found these neurons also tended to express a protein called orexin, a regulator of sleep and feeding -- suggesting a molecular association between depression and some of its symptoms.

Retro-TRAP merges two approaches to understanding the brain: mapping all of the connections within it and profiling gene expression within populations of neurons, Friedman says. "We hope that Retro-TRAP will be broadly used and provide a more granular understanding of how complex neural circuits function and ultimately lead to better treatments for neurological and neuropsychiatric disorders."

Story Source:

The above story is based on materials provided by Rockefeller University. Note: Materials may be edited for content and length.

Journal Reference:

Mats I. Ekstrand, Alexander R. Nectow, Zachary A. Knight, Kaamashri N. Latcha, Lisa E. Pomeranz, Jeffrey M. Friedman. Molecular Profiling of Neurons Based on Connectivity. Cell, 2014; 157 (5): 1230 DOI: 10.1016/j.cell.2014.03.059

New glasses may increase risk of falls in older adults, suggests review

May 23 / 2014

Wolters Kluwer Health: Lippincott Williams & Wilkins

Blurred vision contributes to the risk of falling in older adults -— but getting new glasses with a big change in vision prescription may increase the risk rather than decreasing it, according to a new article. Unaccustomed magnification may cause objects to appear closer or farther than they really are, thus affecting the reflexes linking the vestibular (balance) system with eye movements. For older patients who aren't used to bifocals and "progressive" lenses, switching to these types of lenses may cause distortion in peripheral vision.

Blurred vision contributes to the risk of falling in older adults -- but getting new glasses with a big change in vision prescription may increase the risk rather than decreasing it, according to a special article, '2013 Fry Lecture: Blurred Vision, Spectacle Corr & Falls in Older Adults' in the June issue of Optometry and Vision Science, official journal of the American Academy of Optometry.The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health.

Optometrists can help to prevent falls by avoiding over-aggressive vision correction in older patients at risk, according to the review by David B. Elliott, PhD, 2013 recipient of the prestigious Glenn A. Fry Lecture Award. "Our 2013 Glenn A. Fry Award winner has been studying the effects of blurred vision and vision correction on falls among the elderly," comments Anthony Adams, OD, PhD, Editor-in-Chief of Optometry and Vision Science. "In his Award-winning lecture, he provides some very special insights into how this may happen and how we as a profession may help to minimize falls related to vision loss."

Vision Correction May Actually Increase Risk of Falling

Falls are the major cause of accidental death and nonfatal injuries in elderly US adults. At least one-third of healthy adults aged 65 or older fall at least once a year. For those aged 90 or older, the risk increases to about 60 percent.

But falls in older adults aren't accidents, according to Dr. Elliott. Most of the time, they're related to a wide range of risk factors including older age, disabilities, muscle weakness, and many different medical conditions. "The more risk factors you have, the more likely you are to fall," Dr. Elliott writes.

Reduced vision is one important risk factor, suggesting that interventions to correct vision -- particularly glasses and cataract surgery -- would reduce the risk of falling. Surprisingly, however, most studies have shown little or no reduction in falls among older adults receiving a new vision correction.

Magnification from some new glasses provided in one study may contribute to the increase in risk, Dr. Elliott suggests. "Some of the subjects received large changes in spectacle prescription….Older frail people may have greater difficulty adapting to such changes and be at increased risk of falling during this adaptation period."

New Glasses for Older Patients at Risk of Falls -- 'If It Ain't Broke, Don't Fix It'

Unaccustomed magnification may cause objects to appear closer or farther than they really are, thus affecting the reflexes linking the vestibular (balance) system with eye movements. For older patients who aren't used to bifocals and "progressive" lenses -- with different areas of correction for near and distance vision -- switching to these types of lenses may cause distortion in peripheral vision.

So if maximizing vision correction isn't the answer, what can optometrists do to help prevent the risk of falls in elderly patients? An important first step is to assess risk factors, including history of falls, medical conditions, and medications used.

In addition, Dr. Elliott proposes taking a "conservative" approach to prescribing new glasses for older adults with a history of falls or risk factors for falling. He suggests some changes to the vision prescription for optometrists to consider in this situation. He adds, "Indeed, if a patient reports no problems with vision but simply requests a new frame, 'If it ain't broke don't fix it' is an appropriate clinical maxim."

He also suggests keeping the same type of lens (bifocals, progressive lenses, etc) unless there's a significant reason for change. "Progressive lenses or bifocals should never be prescribed to patients who are used to wearing single-vision glasses and who could be characterized at risk for falls," Dr. Elliott writes. He notes that one randomized controlled trial showed that providing an additional pair of distance vision, single-vision glasses for outdoor mobility use -- as opposed to bifocal or progressive addition lenses -- can reduce falls rate.

Story Source:

The above story is based on materials provided by Wolters Kluwer Health: Lippincott Williams & Wilkins. Note: Materials may be edited for content and length.

Journal Reference:

David B. Elliott. The Glenn A. Fry Award Lecture 2013. Optometry and Vision Science, 2014; 91 (6): 593 DOI: 10.1097/OPX.0000000000000268

Disaster Planning: Risk assessment vital to development of mitigation plans

Wildfires and flooding affect many more people in the USA than earthquakes and landslide and yet the dread, the perceived risk, of the latter two is much greater than for those hazards that are more frequent and cause greater loss of life. Research published in the International Journal of Risk Assessment and Management, suggests that a new paradigm for risk assessment is needed so that mitigation plans in the face of natural disasters can be framed appropriately by policy makers and those in the emergency services.

Maura Knutson (nee Hurley) and Ross Corotis of the University of Colorado, Boulder, explain that earlier efforts for incorporating a sociological perspective and human risk perception into hazard-mitigation plans, commonly used equivalent dollar losses from natural hazard events as the statistic by which to make decisions. Unfortunately, this fails to take into consideration how people view natural hazards, the team reports. Moreover, this can lead to a lack of public support and compliance with emergency plans when disaster strikes and lead to worse outcomes in all senses.

The researchers have therefore developed a framework that combines the usual factors for risk assessment, injuries, deaths and economic and collateral loss with the human perception of the risks associated with natural disasters. The framework includes risk perception by graphing natural hazards against "dread" and "familiarity." These two variables are well known to social psychologists as explaining the greatest variability in an individual's perception of risk, whether considering earthquakes, landslides, wildfires, storms, tornadoes, hurricanes, flooding, avalanche, even volcanic activity. "Understanding how the public perceives the risk for various natural hazards can assist decision makers in developing and communicating policy decisions," the team says.

The higher the perceived risk of a natural disaster, the more people want to see that risk reduced and that means seeing their tax dollars spent on mitigation and preparation. For example, far more money is spent on reducing earthquake risk than on reducing the risk from wildfires, perhaps because the perceived risk is much greater, even though both will cause significant losses of life and property. The team's new framework for risk assessment will act as an aid in decision making for these types of situations as well as perhaps even offering a way to give members of the public a clearer understanding of actual risk rather than perceived risk.

Story Source:

The above story is based on materials provided by Inderscience Publishers. Note: Materials may be edited for content and length.

Journal Reference:

Hurley, M.A. and Corotis, R.B. Perception of risk of natural hazards: a hazard mitigation plan framework. International Journal of Risk Assessment and Management, May 2014

Eumelanin's secrets: Discovery of melanin structure may lead to better sun protection

May 22 / 2014

Massachusetts Institute of Technology

Melanin -- and specifically, the form called eumelanin -- is the primary pigment that gives humans the coloring of their skin, hair, and eyes. It protects the body from the hazards of ultraviolet and other radiation that can damage cells and lead to skin cancer, but the exact reason why the compound is so effective at blocking such a broad spectrum of sunlight has remained something of a mystery. Now researchers at MIT and other institutions have solved that mystery, potentially opening the way for the development of synthetic materials that could have similar light-blocking properties.

A snapshot from a molecular dynamics simulation shows the geometric order and disorder characteristics of eumelanin aggregate structures. The different variations of the eumelanin molecules are shown in different colors for clarity.

Now researchers at MIT and other institutions have solved that mystery, potentially opening the way for the development of synthetic materials that could have similar light-blocking properties. The findings are published in the journal Nature Communications by graduate students Chun-Teh Chen and Chern Chuang, professor of civil and environmental engineering Markus Buehler, and three others.

Although eumelanin has been known for decades, pinning down its molecular structure, and identifying the reasons for its broadband light absorption, have been daunting tasks. This is, in part, because of the very characteristics that make it so interesting: Typically, the constituents of a chemical compound can be determined through spectroscopy, among other tools, but in the case of eumelanin the spectrographs don't show the sharp peaks that are ordinarily useful in identification. So indirect means of analysis were needed.

The team used a combination of computation and experimental analysis to derive the structure of the material, finding that a major source of the broadband absorption was the physical arrangement of the constituents, not their chemical characteristics. Specifically, the combination of disorder and order in the physical arrangement produces a "smearing" of the material's spectral absorption, and providing its crucial broadband blocking ability.

"You can't do traditional analytical chemistry on this particular system," Chuang, a graduate student in chemistry, says, "where you isolate each component. Only indirect ways of probing" can be used, he says.

The disorder that turned out to be key, the team says -- a physical disorder called "geometric disorder" -- is different from the chemical disorder that other researchers have studied. It turns out that both kinds of disorder may play a complementary role in producing eumelanin's broadband absorption.

The material forms tiny crystals -- a chemically ordered state -- but with intrinsic randomness, such that the orientations of the stacked molecules can be arbitrary and the sizes of the crystals different, forming aggregate structures that are highly disordered. That combination of order and disorder contributes to eumelanin's broadband absorption, the team found.

"It's a naturally existing nanocomposite," Buehler says, "that has very critical macroscopic properties as a result of the nanostructure."

While eumelanin molecules all share a basic chemistry, more than 100 variations of that composition exist; the slight variations from one molecule to another may contribute to the disorder that broadens the ability to absorb light, Buehler says. "The jury is still out on which is more important," he says.

Understanding the origins of eumelanin's optical properties could help guide the creation of new synthetic materials, Buehler says. These insights may be useful in developing materials for applications such as pigments, he says, or in improving the efficiency of solar cells.

While this analysis still leaves open questions about the precise structure of eumelanin molecules, Buehler says, "Building an accurate structural model is one of our big aims."

A similar combination of computational modeling based on quantum mechanics, molecular dynamics, and direct observation using electron microscopy "can probably be applied to many systems," Buehler says. "It's a methodological advance that is validated because this system has such unique optical properties, which we can reproduce. It shows the method can be useful."

Sergei Tretiak, a researcher in the theoretical division at Los Alamos National Laboratory who was not involved in this research, says that understanding eumelanin's structure was "a scientific puzzle for a long time." The new work, he says, "provides a somewhat unexpected answer to this conundrum." The researchers' approach, he says, "exemplifies a multidisciplinary approach to [a] complex problem, where a single method is unable to provide a satisfying answer."

Story Source:

The above story is based on materials provided by Massachusetts Institute of Technology. The original article was written by David L. Chandler. Note: Materials may be edited for content and length.

Journal Reference:

Chun-Teh Chen, Chern Chuang, Jianshu Cao, Vincent Ball, David Ruch, Markus J. Buehler. Excitonic effects from geometric order and disorder explain broadband optical absorption in eumelanin. Nature Communications, 2014; 5 DOI: 10.1038/ncomms4859

New details on microtubules and how the anti-cancer drug Taxol works

May 22 / 2014

DOE/Lawrence Berkeley National Laboratory

Images of microtubule assembly and disassembly have been produced by researchers at the unprecedented resolution of 5 angstroms, providing new insight into the success of the anti-cancer drug Taxol and pointing the way to possible improvements. "This is the first experimental demonstration of the link between nucleotide state and tubulin conformation within the microtubules and, by extension, the relationship between tubulin conformation and the transition from assembled to disassembled microtubule structure," says a biophysicist on the study.

The most detailed look ever at the assembly and disassembly of microtubules, tiny fibers of tubulin protein that play a crucial role in cell division, provides new insight into the success of the anti-cancer drug Taxol.

A pathway to the design of even more effective versions of the powerful anti-cancer drug Taxol has been opened with the most detailed look ever at the assembly and disassembly of microtubules, tiny fibers of tubulin protein that form the cytoskeletons of living cells and play a crucial role in mitosis. Through a combination of high-resolution cryo-electron microscopy (cryo-EM) and new methodology for image analysis and structure interpretation, researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley have produced images of microtubule assembly and disassembly at the unprecedented resolution of 5 angstroms (Å). Among other insights, these observations provide the first explanation of Taxol's success as a cancer chemotherapy agent.

"This is the first experimental demonstration of the link between nucleotide state and tubulin conformation within the microtubules and, by extension, the relationship between tubulin conformation and the transition from assembled to disassembled microtubule structure," says Eva Nogales, a biophysicist with Berkeley Lab's Life Sciences Division who led this research. "We now have a clear understanding of how hydrolysis of guanosine triphosphate (GTP) leads to microtubule destabilization and how Taxol works to inhibit this activity."

Nogales, who is also a professor of biophysics and structural biology at UC Berkeley, as well as an investigator with the Howard Hughes Medical Institute, is the corresponding author of a paper describing this research in the journal Cell. The paper is entitled "High resolution αβ microtubule structures reveal the structural transitions in tubulin upon GTP hydrolysis." Co-authors are Gregory Alushin, Gabriel Lander, Elizabeth Kellogg, Rui Zhang and David Baker.

During mitosis, the process by which a dividing cell duplicates its chromosomes and distributes them between two daughter cells, microtubules disassemble and reform into spindles across which the duplicate sets of chromosomes migrate. For chromosome migration to occur, the microtubules attached to them must disassemble, carrying the chromosomes in the process. The crucial ability of microtubules to transition from a rigid polymerized or "assembled" state to a flexible depolymerized or "disassembled" state -- called "dynamic instability" -- is driven by GTP hydrolysis in the microtubule lattice. Taxol prevents or dramatically slows down the unchecked cell division that is cancer by binding to a microtubule in such a manner as to block the effects of hydrolysis. However, until now the atomic details as to how microtubules transition from polymerized to depolymerized structures and the role that Taxol can play have been sketchy.

"Uncovering the atomic details of the conformational cycle accompanying polymerization, nucleotide hydrolysis, and depolymerization is essential for a complete description of microtubule dynamics," Nogales says. "Such details should significantly aid in improving the potency and selectivity of existing anti-cancer drugs, as well as facilitate the development of novel agents."

To find these details, Nogales, an expert in electron microscopy and image analysis and a leading authority on the structure and dynamics of microtubules, employed cryo-EM, in which protein samples are flash-frozen at liquid nitrogen temperatures to preserve their natural structure. Using an FEI 300 kV Titan cryo-EM from the laboratory of Robert Glaeser, she and her colleagues generated cryo-EM reconstructions of tubulin proteins whose structures were either stabilized by GMPCPP, a GTP analogue, or were unstable and bound to guanosine diphosphate (GDP), or were bound to GDP but stabilized by the presence of Taxol.

The tubulin protein is a heterodimer consisting of alpha (α) and beta (β) monomer subunits. It features two guanine nucleotide binding sites, an "N-site" on the α-tubulin that is buried, and an "E-site" on the β-tubulin that is exposed when the tubulin is depolymerized. Previous microtubule reconstruction studies were unable to distinguish the highly similar α-tubulin and β-tubulin from each other.

"To be able to distinguish the α-tubulin from the β-tubulin, we had to resolve our images at better than 8 Å, which most prior cryo-EM studies were unable to do," Nogales says. "For that, we marked the subunits with kinesin, a protein motor that distinguishes between α- and β-tubulin."

Nogales and her colleagues found that GTP hydrolysis and the release of the phosphate (GTP becomes GDP) leads to a compaction of the E-site and a rearrangement of the α-tubulin monomer that generates a strain on the microtubule that destabilizes its structure. Taxol binding leads to a reversal of this E-site compaction and α-tubulin rearrangement that restores structural stabilization.

"Remarkably, Taxol binding globally reverses the majority of the conformational changes we observe when comparing the GMPCPP and GDP states," Nogales says. "We propose that GTP hydrolysis leads to conformational strain in the microtubule that would be released by bending during depolymerization. This model is consistent with the changes we observe upon taxol binding, which dramatically stabilizes the microtubule lattice. Our analysis supports a model in which microtubule-stabilizing agents like Taxol modulate conformational strain and longitudinal contacts in the microtubule lattice."

Story Source:

The above story is based on materials provided by DOE/Lawrence Berkeley National Laboratory. The original article was written by Lynn Yarris. Note: Materials may be edited for content and length.

Journal Reference:

Gregory Alushin, Gabriel Lander, Elizabeth Kellogg, Rui Zhang and David Baker. High resolution αβ microtubule structures reveal the structural transitions in tubulin upon GTP hydrolysis. Cell, May 2014

Brazilian wandering spider – Deadliest spider in the world

Spider wasp “towing” its prey (photo: “Bugguide.net”)

On a bicycle ride today I had my second encounter with a Brazilian wandering spider.

It was a scene that seemed to come right out of a Animal planet documentary. I had stopped to have a snack, when something caught my eye: about 10m in front of me I saw something that looked like a huge insect crossing the street. I went closer to check it out and to my surprise it was a big black wasp “towing” an even bigger spider to the other side of the road.

I immediately remembered a documentary I once saw about these wasps (spider wasp, Tarantula hawk, Pepsis wasp), that sting the spider to sedate it in order to stay fresh and take it back to the nest, where they deposit an egg on the spider’s body. When the larva emerges from the egg, it has a juicy, still alive, but harmless spider to feed on. Nature sure seems a little gruesome sometimes, no?

I wanted to take a picture with my (very old) cellphone before the duo disappeared in the grass on the other side of the street, but when I got too close, the wasp flew off and it kept flying around me for a few minutes like a fighter jet to scare me away.

The sedated Brazilian wandering spider as it was sitting on the side of the road.

When I finally got my phone out and took a (Ok, kinda crappy) picture of the spider – which was moving a little but wasn’t going anywhere since it was sedated – the wasp was gone, probably off to find another victim. It’s weird, but I actually felt sorry for the defenseless spider.

A fairly large section of the “first aid” chapter of the guiding course I took in Rio de Janeiro, was about snakes and spiders, and at first sight, I had a hunch that this was a Brazilian wandering spider (known in Brazil under the name “Armadeira”) , which is considered the most venomous and deadly spider in the world. Apart from being able to kill a human, the venom also has a very uncommon side effect: it can cause very long lasting but painful erections (priapism).

The Brazilian wandering spider is all the more dangerous because it doesn’t run away when approached, but will aggressively – and very fast – attack anything it considers a threat, and that includes humans. These spiders live in highly populated areas in Brazil and are often found inside houses. They are one of the reasons why you should always check your shoes or clothes before putting them on.

So, with the wasp gone, I was left alone with my Brazilian wandering spider, and I decided to take it home. One of my three water bottles was empty, so I put the unfortunate creature in there for the 50km ride back to Volta Redonda.

Once home, I discovered that the spider had some kind of wound to its abdomen (probably from being dragged over the hot asphalt) and had been loosing fluid, which made the abdomen look a little deflated. I had hoped to keep it for a while, to see whether it eventually would “wake up” from its sedation, but now I guess that will not happen anymore. (RIP)

Brazilian wandering spider: those fangs are impressive and have no problem puncturing human skin. this is one critter to be VERY careful around.

Brazilian wandering spider – The ruler shows this one is about 10cm, but they can grow up to 17cm.

This was yet another reminder for me of the more dangerous side of Brazil, and that these Brazilian wandering spiders, among other venomous animals, like snakes, are indeed out there and something to be reckoned with.

Clipe oficial “Prá sonhar”–Marcelo Jeneci

Prá sonhar.

Florian Hutter, absolutamente incrível

Sempre que posso assisto o vídeo Abba Medley (pout-pourri) com Florian Hutter, cujas músicas foram originalmente interpretadas pelo sensacional conjunto musical “ABBA”.

Interpretação perfeita. Prestando bem atenção, nota-se sua grande habilidade em gerenciar a troca de efeitos, rítmos, através do controles do órgão, aliás, um magnífico instrumento fabricado pela Wersi da Alemanha.

Além do controle total sobre o keyboard, a música original é fielmente reproduzida e até mesmo melhorada pela grande habilidade do então adolescente Florian neste vídeo.

Eu o coloco no mesmo patamar do grande pianista Liberace, embora Liberace tenha produzido bem mais no piano, e nesse instrumento não existe o recurso de efeitos especiais, mas Liberace também foi um gênio.

Ás vezes, Florian exagera em algumas músicas, mas a maioria é simplesmente sensacional. Sinto falta de várias músicas que gostaria de ouvir na interpretação desse fabuloso organista. Caramba, como seria bom ouvir por exemplo “Da cor do pecado”, True Love, Xanadu ( interpretada vocalmente pela fabulosa cantora Olivia Newton-John) e muitas, muitas outras, como por exemplo uma seleção musical do conjunto Roupa Nova, do Quarteto em Cy, seria bom demais.

https://www.youtube.com/watch?v=sPYX66j6ZL4 (Abba Medley)