Genetically engineered animals have been used from decades. These genetically engineered or modified animals play a vital role in the unearthing, development and improvement of new methods and techniques of the treatment of many diseases that had been a threat to the survival and healthy way of life of the mankind. Their different techniques (such as the use of transgenic mice, knockout mice and others) help the genetic engineers and researchers to differentiate new strings of human genome. Due to their graceful work, pharmaceutical industry has grown extensively and helped mankind in the treatment of various deadly diseases and still on the road of development. Because of the development of biomedical research, the use of transgenic animals has been considerably increased. According to the government rules and regulations and other renowned pharmaceutical companies’ inflexible reviews, authorize the use of transgenic animals when there is no alternative left. In the twentieth century, all biomedical and pharmaceutical breakthroughs are the upshot of research on animals.
There are two major techniques for commencing transgenic method in mice, which are pronuclear injection and embryonic stem cells. Pronuclear injection means that peculiar DNA is injected in the pronucleus of a fertilized egg of a mouse which is then integrated in the genome at unsystematic location mostly after two cell divisions. It means that the mouse will be partial transgenic in nature because that peculiar DNA is not a part in each and every cell of the body. The sperms or eggs of these partial transgenic mice are then manipulated to produce entirely Transgenic mice in the next generation. Another method of creating transgenic mice, embryonic stem cells, is inducing DNA in the stem cells of embryo which is randomly integrated in the genome. However, if it has a structure alike to the existing fraction of genome then it goes through the homologous recombination and a sole copy is incorporated at a particular location in the genome. These peculiar cells are then injected into the host embryo, allowing them to grow and be a part of it. Chimera is a terminology that is used for a mouse that is grown from the host embryo, which is created from embryonic cells of two separate mice. Several sperms generated by chimera would be transgenic in nature and as soon as they fertilize a regular egg, the result would be fully transgenic mice comprising that peculiar DNA in every cell.
Guest Post by Sophie Alexander from http://www.transposagenbio.com/
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Wednesday, November 9, 2011
Why fish don't freeze in the Arctic Ocean
Temperatures of minus 1.8 ° C should really be enough to freeze any fish: the freezing point of fish blood is about minus 0.9 ° C. How Antarctic fish are able to keep moving at these temperatures has interested researchers for a long time. As long as 50 years ago, special frost protection proteins were found in the blood of these fish. These so-called anti-freeze proteins work better than any household antifreeze. How they work, however, was still unclear. The Bochum researchers used a special technique, terahertz spectroscopy, to unravel the underlying mechanism. With the aid of terahertz radiation, the collective motion of water molecules and proteins can be recorded. Thus, the working group has already been able to show that water molecules, which usually perform a permanent dance in liquid water, and constantly enter new bonds, dance a more ordered dance in the presence of proteins – "the disco dance becomes a minuet" says Prof. Havenith.
Souvenir from an Antarctic expedition
The subject of the current investigations was the anti-freeze glycoproteins of the Antarctic toothfish Dissostichus mawsoni, which one of the American partners, Arthur L. Devries, had fished himself on an Antarctic expedition. "We could see that the protein has an especially long-range effect on the water molecules around it. We speak of an extended dynamical hydration shell", says co-author Konrad Meister. "This effect, which prevents ice crystallization, is even more pronounced at low temperatures than at room temperature", adds Prof. Havenith. Nevertheless, to freeze the water, lower temperatures would be necessary. Complexation of the AFP by borate strongly reduces the antifreeze activity. In this case, the researchers also found no change in the terahertz dance. The researchers' results provide evidence for a new model of how AFGPs prevent water from freezing: Antifreeze activity is not achieved by a single molecular binding between the protein and the water, but instead AFP perturbs the aqueous solvent over long distances. The investigation demonstrated for the first time a direct link between the function of a protein and its signature in the terahertz range. The studies were funded by the Volkswagen Foundation.
Source : Ruhr-University BochumM I B S I T B T
Souvenir from an Antarctic expedition
The subject of the current investigations was the anti-freeze glycoproteins of the Antarctic toothfish Dissostichus mawsoni, which one of the American partners, Arthur L. Devries, had fished himself on an Antarctic expedition. "We could see that the protein has an especially long-range effect on the water molecules around it. We speak of an extended dynamical hydration shell", says co-author Konrad Meister. "This effect, which prevents ice crystallization, is even more pronounced at low temperatures than at room temperature", adds Prof. Havenith. Nevertheless, to freeze the water, lower temperatures would be necessary. Complexation of the AFP by borate strongly reduces the antifreeze activity. In this case, the researchers also found no change in the terahertz dance. The researchers' results provide evidence for a new model of how AFGPs prevent water from freezing: Antifreeze activity is not achieved by a single molecular binding between the protein and the water, but instead AFP perturbs the aqueous solvent over long distances. The investigation demonstrated for the first time a direct link between the function of a protein and its signature in the terahertz range. The studies were funded by the Volkswagen Foundation.
Source : Ruhr-University BochumM I B S I T B T
Mosquitoes use several different kinds of odor sensors to track human prey...Quite intelligent..!!!
It now appears that the malaria mosquito needs more than one family of odor sensors to sniff out its human prey. The experiments described in the paper provide striking new evidence that Anopheles gambiae – the species of mosquito that spreads malaria that infects some 250 million and kills 900,000 people annually – has a second set of olfactory sensors that are fundamentally different from the set of sensors that scientists have known about and have been studying for the last 10 years.
The discovery may help explain a puzzling question that has been plaguing scientists trying to develop new and more effective forms of mosquito lures and repellents: "The ORs [odorant receptors] that were identified in the lab before don't respond to a lot of human odors," says Vanderbilt graduate student Chao Liu, who is the lead author on the paper. "Now that we have a new set of receptors, we may be able to fill in the picture."
There is a good chance that this new set of receptors may be specifically tuned to detect a number of the odorants given off by humans, adds co-author R. Jason Pitts, a senior research specialist and graduate student at Vanderbilt. "If this is the case then it is quite likely that it will play a critical role in attempts to develop improved lures and repellents to control the spread of malaria." According to Pitts, they also have preliminary evidence that the mosquito's olfactory system may include additional families of sensors as well.
Vanderbilt Professor of Biological Sciences and Pharmacology Laurence Zwiebel, who was the principal investigator on the study, heads a major interdisciplinary research project to develop new ways to control by spread of malaria based on mosquito olfaction supported by the Grand Challenges in Global Health Initiative funded by the Foundation for NIH through a grant from the Bill & Melinda Gates Foundation.
"It's not at all surprising that the mosquito's olfactory system is more sophisticated than we thought," says Zwiebel. "Olfaction is absolutely essential to the mosquito. If the female cannot find a host for a blood meal she cannot reproduce. As a result, mosquitoes have developed an uncanny ability to detect odors. This is true of all species of mosquitoes, not just Anopheles. So it is highly likely that the mosquitoes that spread West Nile, dengue fever, yellow fever and encephalitis also have similar sets of odor sensors."
About ten years ago, when the mosquito genome was first sequenced, scientists at Vanderbilt and Yale identified the genes and the structure of one set of Anopheles sensors, called odorant receptors (AgORs). At first, they thought that these receptors had the same basic design as the sensors found in the nose of humans and other mammals. But recent studies have found that the mosquito receptors, along with those of several other insects, have a distinctly different structure.
Researchers have identified about 75 different AgORs that respond to a variety of volatile compounds. These receptors are expressed on the surface of nerves located in tiny hollow spikes, called sensilla, located on the mosquito's antennae. When a target molecule wafts into the interior of one of these sensilla and comes into contact with the AgOR designed to detect it, the receptor causes the nerve to fire, signaling the compound's presence. Earlier this year the Vanderbilt researchers and their colleagues at Yale succeeded in pairing more than 40 of the AgORs with the specific odorants that trigger them. In the process, the researchers discovered that these receptors are broadly tuned. That is, each receptor responds to a number of different compounds. They also overlap. More than one AgOR responds to individual odorants.
As a result, last year when scientists at Rockefeller University announced they had discovered a second set of olfactory receptors in the fruit fly Drosophila melanogaster, an animal model for basic genetics, "it was like a light switched on," says Pitts. Because of the many parallels between the olfactory systems of the fruit fly and mosquito, the Vanderbilt researchers knew it was extremely likely that the mosquito had a second set of receptors as well. So they began searching for them.The search was successful and the researchers identified genes that code for about 50 versions of the new type receptor. The new receptors appear to have a slightly different structure from that of AgORs: They are called "ionotropic receptors" (AgIRs) and they closely resemble the type of receptor found in the brain that responds to the common neurotransmitter, glutamate.
At this point, the researchers can only speculate about what effect this structural difference has on the way that the AgIRs function as odor detectors. However, they have managed to associate an AgIR with butylamine, a human odorant that AgORs do not appear to identify. Butylamine sensitivity is located in grooved peg sensilla, a type of sensory hair on the mosquito antennae. The correlation of AgIR to butylamine could indicate that AgIRs are responsible for grooved peg sensilla sensitivities to other human odors such as ammonia and lactic acid, an idea that the Zwiebel Lab has begun exploring.
The basic problem facing the mosquito searching for human prey – and the humans who are trying to figure out how it does it – is that none of the hundreds of odors given off by humans are necessarily unique. They are actually produced by the bacteria that live on human skin. But these bacteria live on other animals as well. So the current theory is that mosquitoes must identify a blend of different odorants that provide a unique signature for humans. Determining the way that the AgIRs work may be the key to identifying such a signature and that, in turn, could be the key to developing non-toxic, ecologically benign methods for combating malaria and other mosquito-borne illnesses.
Source : Vanderbilt University
The discovery may help explain a puzzling question that has been plaguing scientists trying to develop new and more effective forms of mosquito lures and repellents: "The ORs [odorant receptors] that were identified in the lab before don't respond to a lot of human odors," says Vanderbilt graduate student Chao Liu, who is the lead author on the paper. "Now that we have a new set of receptors, we may be able to fill in the picture."
There is a good chance that this new set of receptors may be specifically tuned to detect a number of the odorants given off by humans, adds co-author R. Jason Pitts, a senior research specialist and graduate student at Vanderbilt. "If this is the case then it is quite likely that it will play a critical role in attempts to develop improved lures and repellents to control the spread of malaria." According to Pitts, they also have preliminary evidence that the mosquito's olfactory system may include additional families of sensors as well.
Vanderbilt Professor of Biological Sciences and Pharmacology Laurence Zwiebel, who was the principal investigator on the study, heads a major interdisciplinary research project to develop new ways to control by spread of malaria based on mosquito olfaction supported by the Grand Challenges in Global Health Initiative funded by the Foundation for NIH through a grant from the Bill & Melinda Gates Foundation.
"It's not at all surprising that the mosquito's olfactory system is more sophisticated than we thought," says Zwiebel. "Olfaction is absolutely essential to the mosquito. If the female cannot find a host for a blood meal she cannot reproduce. As a result, mosquitoes have developed an uncanny ability to detect odors. This is true of all species of mosquitoes, not just Anopheles. So it is highly likely that the mosquitoes that spread West Nile, dengue fever, yellow fever and encephalitis also have similar sets of odor sensors."
About ten years ago, when the mosquito genome was first sequenced, scientists at Vanderbilt and Yale identified the genes and the structure of one set of Anopheles sensors, called odorant receptors (AgORs). At first, they thought that these receptors had the same basic design as the sensors found in the nose of humans and other mammals. But recent studies have found that the mosquito receptors, along with those of several other insects, have a distinctly different structure.
Researchers have identified about 75 different AgORs that respond to a variety of volatile compounds. These receptors are expressed on the surface of nerves located in tiny hollow spikes, called sensilla, located on the mosquito's antennae. When a target molecule wafts into the interior of one of these sensilla and comes into contact with the AgOR designed to detect it, the receptor causes the nerve to fire, signaling the compound's presence. Earlier this year the Vanderbilt researchers and their colleagues at Yale succeeded in pairing more than 40 of the AgORs with the specific odorants that trigger them. In the process, the researchers discovered that these receptors are broadly tuned. That is, each receptor responds to a number of different compounds. They also overlap. More than one AgOR responds to individual odorants.
As a result, last year when scientists at Rockefeller University announced they had discovered a second set of olfactory receptors in the fruit fly Drosophila melanogaster, an animal model for basic genetics, "it was like a light switched on," says Pitts. Because of the many parallels between the olfactory systems of the fruit fly and mosquito, the Vanderbilt researchers knew it was extremely likely that the mosquito had a second set of receptors as well. So they began searching for them.The search was successful and the researchers identified genes that code for about 50 versions of the new type receptor. The new receptors appear to have a slightly different structure from that of AgORs: They are called "ionotropic receptors" (AgIRs) and they closely resemble the type of receptor found in the brain that responds to the common neurotransmitter, glutamate.
At this point, the researchers can only speculate about what effect this structural difference has on the way that the AgIRs function as odor detectors. However, they have managed to associate an AgIR with butylamine, a human odorant that AgORs do not appear to identify. Butylamine sensitivity is located in grooved peg sensilla, a type of sensory hair on the mosquito antennae. The correlation of AgIR to butylamine could indicate that AgIRs are responsible for grooved peg sensilla sensitivities to other human odors such as ammonia and lactic acid, an idea that the Zwiebel Lab has begun exploring.
The basic problem facing the mosquito searching for human prey – and the humans who are trying to figure out how it does it – is that none of the hundreds of odors given off by humans are necessarily unique. They are actually produced by the bacteria that live on human skin. But these bacteria live on other animals as well. So the current theory is that mosquitoes must identify a blend of different odorants that provide a unique signature for humans. Determining the way that the AgIRs work may be the key to identifying such a signature and that, in turn, could be the key to developing non-toxic, ecologically benign methods for combating malaria and other mosquito-borne illnesses.
Source : Vanderbilt University
Wednesday, October 12, 2011
Tuesday, September 13, 2011
Are sharks color blind?
Sharks are unable to distinguish colors, even though their close relatives rays and chimaeras have some color vision, according to new research by Dr. Nathan Scott Hart and colleagues from the University of Western Australia and the University of Queensland in Australia. Their study shows that although the eyes of sharks function over a wide range of light levels, they only have a single long-wavelength-sensitive cone* type in the retina and therefore are potentially totally color blind. Hart and team's findings are published online in Springer's journal Naturwissenschaften – The Science of Nature.
"This new research on how sharks see may help to prevent attacks on humans and assist in the development of fishing gear that may reduce shark bycatch in long-line fisheries. Our study shows that contrast against the background, rather than colour per se, may be more important for object detection by sharks. This may help us to design long-line fishing lures that are less attractive to sharks as well as to design swimming attire and surf craft that have a lower visual contrast to sharks and, therefore, are less 'attractive' to them," said Prof. Hart.
Sharks are efficient predators and their evolutionary success is thought to be due in part to an impressive range of sensory systems, including vision. To date, it is unclear whether sharks have color vision, despite well-developed eyes and a large sensory brain area dedicated to the processing of visual information. In an attempt to demonstrate whether or not sharks have color vision, Hart and colleagues used a different technique - microspectrophotometry - to identify cone visual pigments in shark retinas and measure their spectral absorbance.
They looked at the retinas of 17 shark species caught in a variety of waters in both Queensland and Western Australia. Rod cells were the most common type of photoreceptor in all species. In ten of the 17 species, no cone cells were observed. However, cones were found in the retinae of 7 species of shark from three different families and in each case only a single type of long-wavelength-sensitive cone photoreceptor was present. Hart and team's results provide strong evidence that sharks possess only a single cone type, suggesting that sharks may be cone monochromats, and therefore potentially totally color blind.
The authors conclude : "While cone monochromacy on land is rare, it may be a common strategy in the marine environment. Many aquatic mammals − whales, dolphins and seals − also possess only a single, green-sensitive cone type. It appears that both sharks and marine mammals may have arrived at the same visual design by convergent evolution, in other words, they acquired the same biological trait in unrelated lineages."
Source : Springer
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New TB vaccine enters proof-of-concept trial in people living with HIV
Aeras and the Oxford-Emergent Tuberculosis Consortium (OETC) announce today the start of a Phase IIb proof-of-concept efficacy trial of a new investigational tuberculosis (TB) vaccine that involves people living with the human immunodeficiency virus (HIV). The trial will be conducted at research sites in Senegal and South Africa with primary funding support from the European and Developing Countries Clinical Trials Partnership (EDCTP). TB is a leading cause of death for people infected with HIV and the second leading infectious disease killer in the world. This is the first proof-of-concept efficacy trial in people infected with HIV using MVA85A, which is being developed by OETC (a joint venture between the University of Oxford and Emergent BioSolutions) and Aeras. It is expected that the trial will generate important safety, immunogenicity and efficacy data about this vaccine.
The trial will test the vaccine candidate in approximately 1,400 adults ages 18-50 who are infected with HIV. The study will be led by the UK Medical Research Council in The Gambia, Aeras, and the University of Oxford, and conducted at two sites by the University of Cape Town (UCT) Institute of Infectious Disease and Molecular Medicine in Khayelitsha, South Africa and Laboratoire de Bacteriologie-Virologie du Centre Hospitalier Universitaire Aristide Le Dantec in Dakar, Senegal. This follows the first proof-of-concept clinical trial of the same candidate TB vaccine, which recently reached full enrollment with almost 3,000 infant participants in South Africa. "Clinical trials of new vaccines against tuberculosis must be an urgent priority on our agenda, as too many lives are lost to TB, especially among people living with HIV," said Member of the European Parliament Michael Cashman. "I recently visited a clinical trial site of this vaccine candidate in infants in South Africa, and I was impressed with the progress. I am anxious to see a new TB vaccine licensed, and I am proud that European Union Member States are investing in this critically-important work."
Professor Charles Mgone, Executive Director of EDCTP, said, "The TB and HIV co-epidemic is devastating, requiring a concerted global response. EDCTP in partnership with Aeras, Oxford-Emergent Tuberculosis Consortium and others is committed to accelerate research and development of this promising vaccine against tuberculosis by co-financing the clinical trial as an essential part in its evaluation."
Tuberculosis kills 1.7 million people per year, and more than two billion people worldwide are infected with TB Рapproximately one out of every three people on the planet. People infected with HIV living in countries with high TB prevalence are 20 times more likely to develop TB than those who are HIV-negative. In 2008, there were an estimated 1.4 million new cases of TB among persons with HIV infection, and TB accounted for 23 percent of AIDS-related deaths, according to the World Health Organization (WHO). The Bacille Calmette-Gu̩rin (BCG) vaccine, the only currently-licensed vaccine against TB, is not effective in preventing adult pulmonary TB, the most common form of the disease. "A new, more effective TB vaccine would be game-changing in international efforts to eliminate TB globally by 2050," said Jim Connolly, President and Chief Executive Officer of Aeras. "Studies have already shown that this promising vaccine has an acceptable safety profile and stimulates strong immune responses in HIV-infected individuals."
Aeras is the trial sponsor, and significant funding is provided by EDCTP, a pan-European body that supports multicenter projects which combine clinical trials, capacity building and networking. This study has been approved by the Medicines Control Council of South Africa, the South African Department of Health, and the Comité National d'Ethique pour la Recherche en Santé (CNERS) in Senegal. The Scientific Institute of Public Health (WIV-ISP) in Belgium, which first identified the antigen 85A for possible use in a vaccine candidate, is providing in-kind laboratory services for the study. "Together with our partners, Emergent BioSolutions is proud to be leading the development of a new vaccine to defeat TB, one of the world's deadliest infectious diseases. This trial is particularly critical because of its focus on adults living with HIV. If we are successful, MVA85A will help make the dream of a world free from TB a reality," said Fuad El-Hibri, Chairman and Chief Executive Officer of Emergent BioSolutions.
"It is great to see the vaccine candidate we initially developed at Oxford University reach this stage of clinical trials," said Dr. Helen McShane, a Wellcome Trust Senior Clinical Research Fellow at the University of Oxford. "In the next few years we should begin to get results on how effective the vaccine is in protecting those who are most at risk of TB. It's our hope that this vaccine will turn out to be a powerful new weapon to combat TB in the parts of the world that need it most."
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Like humans, amoebae pack a lunch before they travel
Some amoebae do what many people do. Before they travel, they pack a lunch.
In results of a study reported today in the journal Nature, evolutionary biologists Joan Strassmann and David Queller of Rice University show that long-studied social amoebae Dictyostellum discoideum (commonly known as slime molds) increase their odds of survival through a rudimentary form of agriculture. Research by lead author Debra Brock, a graduate student at Rice, found that some amoebae sequester their food--particular strains of bacteria--for later use.
"We now know that primitively social slime molds have genetic variation in their ability to farm beneficial bacteria as a food source," says George Gilchrist, program director in the National Science Foundation's Division of Environmental Biology, which funded the research. "But the catch is that with the benefits of a portable food source, comes the cost of harboring harmful bacteria." After these "farmer" amoebae aggregate into a slug, they migrate in search of nourishment--and form a fruiting body, or a stalk of dead amoebae topped by a sorus, a structure containing fertile spores. Then they release the bacteria-containing spores to the environment as feedstock for continued growth.
The findings run counter to the presumption that all "Dicty" eat everything in sight before they enter the social spore-forming stage. Non-farmer amoebae do eat everything, but farmers were found to leave food uneaten, and their slugs don't travel as far. Perhaps because they don't have to. The advantages of going hungry now to ensure a good food supply later are clear, as farmers are able to thrive in environments in which non-farmers find little food. The researchers found that about a third of wild-collected Dicty are farmers. Instead of consuming all the bacteria they encounter, these amoebae eat less and incorporate bacteria into their migratory systems.
Brock showed that carrying bacteria is a genetic trait by eliminating all living bacteria from four farmers and four non-farmers--the control group--by treating them with antibiotics. All amoebae were grown on dead bacteria; tests confirmed that they were free of live bacteria. When the eight clones were then fed live bacteria, the farmers all regained their abilities to seed bacteria colonies, while the non-farmers did not. Dicty farmers are always farmers; non-farmers never learn.
Rice graduate student Tracy Douglas co-authored the paper with Brock, Queller and Strassmann. She confirmed that farmers and non-farmers belong to the same species and do not form a distinct evolved group. Still, mysteries remain.
The researchers want to know what genetic differences separate farmers from non-farmers. They also wonder why farmer clones don't migrate as far as their counterparts.
It might be a consequence of bacterial interference, they say, or an evolved response, since farmers carry the seeds of their own food supply and don't need to go as far. Also, some seemingly useless or even harmful bacteria are not consumed as food, but may serve an as-yet-undetermined function, Brock says.
That has implications for treating disease as it may, for instance, provide clues to the way tuberculosis bacteria invade cells, says Strassmann, infecting the host while resisting attempts to break them down. The results demonstrate the importance of working in natural environments with wild organisms whose complex ties to their living environment have not been broken.
Source : National Science Foundation
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Your genome in minutes: New technology could slash sequencing time
Scientists from Imperial College London are developing technology that could ultimately sequence a person's genome in mere minutes, at a fraction of the cost of current commercial techniques.
The researchers have patented an early prototype technology that they believe could lead to an ultrafast commercial DNA sequencing tool within ten years. Their work is described in a study published this month in the journal 'Nano Letters' and it is supported by the Wellcome Trust Translational Award and the Corrigan Foundation.
The research suggests that scientists could eventually sequence an entire genome in a single lab procedure, whereas at present it can only be sequenced after being broken into pieces in a highly complex and time-consuming process. Fast and inexpensive genome sequencing could allow ordinary people to unlock the secrets of their own DNA, revealing their personal susceptibility to diseases such as Alzheimer's, diabetes and cancer. Medical professionals are already using genome sequencing to understand population-wide health issues and research ways to tailor individualised treatments or preventions.
Dr Joshua Edel, one of the authors on the study from the Department of Chemistry at Imperial College London, said: "Compared with current technology, this device could lead to much cheaper sequencing: just a few dollars, compared with $1m to sequence an entire genome in 2007. We haven't tried it on a whole genome yet but our initial experiments suggest that you could theoretically do a complete scan of the 3,165 million bases in the human genome within minutes, providing huge benefits for medical tests, or DNA profiles for police and security work. It should be significantly faster and more reliable, and would be easy to scale up to create a device with the capacity to read up to 10 million bases per second, versus the typical 10 bases per second you get with the present day single molecule real-time techniques."
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Learning the language of bacteria
Bacteria are among the simplest organisms in nature, but many of them can still talk to each other, using a chemical "language" that is critical to the process of infection. Sending and receiving chemical signals allows bacteria to mind their own business when they are scarce and vulnerable, and then mount an attack after they become numerous enough to overwhelm the host's immune system.
This system, called "quorum sensing," is an interesting example of sophistication among microbes, says Helen Blackwell, an associate professor of chemistry at the University of Wisconsin-Madison. In practical terms, she adds, quorum sensing may provide an alternative therapeutic target as bacteria continue to evolve resistance to antibiotics.
Theoretically, blocking quorum sensing would prevent the bacteria from turning pathogenic and producing the toxins that are an immediate cause of disease in bacterial infections.
Bacteria use simple chemical signals to control quorum sensing, and Blackwell is interested in how these compounds work and in developing new ways to intercept them. In a study just published online in the journal ChemBioChem, Blackwell and colleagues Andrew Palmer, Evan Streng and Kelsea Jewell showed that several species of bacteria can respond to identical signals, suggesting that one drug could battle quorum sensing in several types of bacteria. Many bacteria use a class of molecules called lactones for quorum sensing, and Blackwell's lab has synthesized many non-native lactones, and then tested them in two species of bacteria that use identical native lactone signals. Overall, the organisms responded similarly to the same synthetic molecules, despite the dramatic differences between the species. These results suggest that the same basic chemical sensing mechanism could be common among microbes, Blackwell says. "That tells us that we can use these classes of chemicals to study — and perhaps eventually fight — a much broader range of bacteria."
Finding a broad-spectrum activity for the synthetic lactones is good news, Blackwell adds. "Bacteria come in countless varieties, and the ability to target multiple organisms with one compound could streamline the search for drugs. At the same time, we also have found differences in signal selectivity that may allow us to target some bacteria while ignoring others." That could provide the best of both worlds, Blackwell says. One drug might halt multiple infections, but related drugs might affect only one microbe in a mixture. "The data indicate that it should be possible to design and use compounds that are either selective or broad-spectrum."
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Tuesday, July 5, 2011
How we come to know our bodies as our own
[PRESS RELEASE, 17 June 2011] By taking advantage of a 'body swap' illusion, researchers at Karolinska Institutet have captured the brain regions involved in one of the most fundamental aspects of self-awareness: how we recognize our bodies as our own, distinct from others and from the outside world. That self-perception is traced to specialized multisensory neurons in various parts of the brain that integrate different sensory inputs across all body parts into a unified view of the body. The findings, reported in the journal Current Biology, may have important medical and industrial applications. 
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Activity in the brain associated with the illusion of owning a manniquin's body. Credit: Current Biology and the study authors
"When we look down at our body, we immediately experience that it belongs to us," says Valeria Petkova, one of the researchers behind the study. "We do not experience our body as a set of fragmented parts, but rather as a single entity. Our study is the first to tackle the important question of how we come to have the unitary experience of owning an entire body."
Earlier studies showed that the integration of visual, tactile and proprioceptive information (the sense of the relative position of body parts) in multisensory areas constitutes a mechanism for the self-attribution of single limbs, the researchers explained. But how ownership of individual body parts translates into the unitary experience of owning a whole body remained a mystery.
In the current study, the researchers used a 'body-swap' illusion, in which people experienced a mannequin to be their own, in combination with functional magnetic resonance imaging (fMRI). Participants observed touching of the mannequi's body from the point of view of the mannequin's head while feeling identical synchronous touches on his or her own body, which they could not see. Those studies revealed a tight coupling between the experience of full-body ownership and neural responses in brain regions known to represent multisensory processing nodes in the primate brain, specifically the bilateral ventral premotor and left intraparietal cortices and the left putamen.
Activation in those multisensory areas was stronger when the stimulated body part was attached to a body, as compared with when it was detached, they report, evidence that the integrity between body segments facilitates ownership of the parts. According to the researchers, the findings suggest that the integration of visual, tactile and proprioceptive information in body-part-centered reference frames represents a basic neural mechanism underlying the feeling of ownership of entire bodies.
"Understanding the mechanisms underlying the self-attribution of a body in the healthy brain can help developing better diagnostic and therapeutic strategies to address pathological disturbances of bodily self- perception," says Associate Professor Henrik Ehrsson, who led the study. "In addition, understanding the mechanisms of perceiving an entire body or a body part as belonging to oneself can have important implications for the design and production of mechanical prosthesis or robotic substitutes for paralyzed or amputated body parts."
Publication:
Valeria I. Petkova, Malin Björnsdotter, Giovanni Gentile, Tomas Jonsson, Tie-Qiang Li, H. Henrik Ehrsson
From part to whole body ownership in the multisensory brain
Current Biology, Volume 21; Issue 13, online 16 June 2011
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Last modified by: Katarina Sternudd 2011-06-17
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