14 Dec 2012

The next generation of European researchers in the life sciences


In mid-November, the European Molecular Biology Organization (EMBO) announced this year’s EMBO Young Investigators. 22 researchers from twelve countries were selected from over 160 applicants; I talked to three of them.


The EMBO Young Investigator Programme (YIP) supports talented researchers at the start of their independent careers by making their research stand out in the scientific community. Being an EMBO Young Investigator helps the young group leaders establish a reputation as outstanding scientists and ensure additional funding for their research. This year's successful applicants receive 15,000 euros annually for three years, in addition to conference grants for themselves and their team members. Additionally, they will get access to the European Molecular Biology Laboratory (EMBL) core facilities and funds for networking opportunities such as student exchanges or visits to other members’ institutes. The 22 newly selected young scientists join a vibrant network of nearly 300 current and former young investigators.

Melina Schuh
Melina Schuh from the Laboratory of Molecular Biology (LMB) of the Medical Research Council in the UK is one of the eight women selected this year. She chose a rather unusual career path as she decided to apply directly for an independent position after her PhD. “I was delighted when I was accepted as a group leader at the LMB, which is one of the birthplaces of modern molecular biology and has attracted 14 Nobel prizes,” Schuh says. During her PhD at the EMBL, Schuh established methods to examine the entire process of meiotic maturation in live mouse oocytes, which she now uses to investigate the causes of aneuploidy in mammalian oocytes. “Because errors during oocyte maturation lead to pregnancy loss, birth defects and infertility, this work does not only provide important insights into fundamental cellular mechanisms, but also has important implications for human health,” she explains. Schuh believes the EMBO YIP is an “excellent networking platform that unites the next generation of European group leaders in the life sciences”.

Bruno Reversade
Bruno Reversade set up his lab in 2008 at the A*STAR Institute of Medical Biology, and is the first scientist based in Singapore to become an EMBO Young Investigator. Reversade investigates hereditary human diseases such as accelerated ageing and some types of cancer, as well as unusual embryological events like identical twinning. “We start off with patients, find the causative gene and examine the pathogenesis of the disease using animal models and patient’s cells in culture,” Reversade says. He hopes that unlocking the molecular mechanisms of rare genetic disorders will advance our understanding of human embryonic development and lead to new treatments, for instance using genetic therapy. “The genetic diseases we study might be rare themselves but the phenotypes they cause are common: for instance, accelerated ageing provides insights into normal ageing.” Reversade plans to strengthen collaborations between the EMBO and the Singaporean A*STAR institutes and to organise the EMBO Young Investigators conference in Singapore in 2015.

Evi Soutoglou
In addition to offering annual meetings, where former and new young investigators have the opportunity to network, the EMBO YIP proposes to pair young investigators with EMBO Members as their mentors. Evi Soutoglou from the Institute of Genetics, Molecular and Cellular Biology in France believes that these networking opportunities with more experienced scientists will be extremely helpful. “I wish I had this opportunity 3 years ago when I was establishing my group,” she says. “This might have helped me to avoid some mistakes.” Soutoglou is interested in understanding how DNA repair is organised in time and in space inside the nucleus of eukaryotic cells. She has developed a unique system to induce DNA breaks and follow the fate of the damaged DNA in living cells. She hopes that becoming an EMBO Young Investigator will increase the visibility of her research and attract “very good people” to join her team.

Image credits: EMBO, MRC Laboratory of Molecular Biology, A*STAR Institute of Medical Biology, Institute of Genetics, Molecular and Cellular Biology.

This article was published in Lab Times on 14-12-2012. You can read it here


7 Dec 2012

Smoking: the beginning of the end?


The first time on an airplane is one of those experiences that leave a stamp on your memory. My first plane trip was about 20 years ago, and I would have great recollections of that flight if not only for what happened after the 'no smoking' lights went out. Shortly after the 'ding', a cloud of cigarette smoke filled the air cabin. For hours on end, I was crammed with over hundred other people in a small, enclosed space breathing recycled smoke-infested air. Not a pleasant memory.

As appalling as this may seem today, smoking on airplanes was only banned by most airlines in the late 1990s. Since then, smoke-free laws have been gradually introduced by many countries in public transportation, hospitals and workplaces, and more recently, in indoor public spaces such as bars and restaurants.


Smoking kills up to half of its users. This is the grim reality that slaps you in the face when you read the tobacco fact sheet of the World Heath Organization (WHO). A staggering amount of scientific evidence accumulated over the past 50 years shows that smoking causes several types of cancer, cardio-vascular and respiratory diseases. Nevertheless, smoking kills over 5 million people every year and the death toll continues to rise, especially in low and middle-income countries. 

To tackle this global tobacco epidemic, the WHO established the Framework Convention on Tobacco Control in 2005. More than 170 countries have joined this treaty and agreed to put into practice a set of public health policies to protect people from second-hand smoking, to combat tobacco illegal trade and to encourage smokers to quit.

Do tobacco control policies work?
Brazil is one of the pioneer countries in implementing such policies for tobacco control. In 1990, Brazil introduced the first rises in cigarette taxes, which doubled cigarette prices in just ten years. This and other subsequent anti-smoking policies such as smoking bans on public spaces and tobacco marketing restrictions for instance, led to a remarkable drop in smoking rates from 35% in 1989 to nearly half in 2008. But it wasn't known which policies were responsible for this steep decline in the number of smokers.

In a new study published in PLoS Medicine, David Levy from Georgetown University used a computational model to answer this question. Levy found that as much as half of the reduction in smoking rates was due to cigarette price increases alone, while smoking bans and marketing controls each accounted for a 14% drop, and other policies contributed slightly less. The raw numbers are even more impressive: the model estimates that anti-smoking policies saved over 400 thousand lives over the past 20 years in Brazil, and the prediction is that by 2050 almost 7 million more lives will be saved. 

Brazil's success story tells us that anti-smoking measures can work even in low to middle-income countries, where smoking is more prevalent. However, Levy's model estimates that an additional 1.3 million deaths could be prevented by 2050 if stricter policies were introduced. So are tougher anti-smoking policies needed to eradicate smoking all together? The answer might be found on the other side of the globe.



A licence to smoke
Australia is a country strongly engaged in reducing smoking and protecting second-hand smokers. In the past 30 years since the first anti-smoking policies were implemented, the number of smokers in Australia has dropped from 34% of the population to 15% in 2010. Last week the Australian government introduced a complete ban on tobacco company logos and coloured cigarette packets, which now have a uniform greyish colour and display health warnings and gruesome images of people with smoking-related diseases (the company name is in small print at the bottom of the packet). Plain packaging might represent the beginning of the end of the smoking industry in Australia, but tobacco control activists think more can be done. 

"We are the first nation to introduce plain packaging, we have the largest per capita spend on hard-hitting campaigns, some of the most expensive cigarettes in the world, but still 14% of adults smoke and it continues to kill more people, by far, than any other cause of death" says Simon Chapman, an expert in Public Health and Tobacco Control at the University of Sydney "We don't give up at 14%".

Chapman recently proposed the controversial idea of a 'smoking licence' that would limit the access to tobacco products. He believes it is unacceptable that even though tobacco threatens both personal and public health, it can be sold anywhere and to anyone with hardly any controls. The smoker's licence would be accepted only in licensed retailers and have a set limit of cigarettes per day (the higher the limit, the more you pay). The idea is that because the access to tobacco products would be limited, young people would be put off from smoking and adult users would be encouraged to quit. 

Jeff Collin from the Global Public Health Unit at the University of Edinburgh is against the smoker's licence: 

"I think it's very unlikely that such a proposal would receive necessary levels of support for it to be politically feasible, and it could jeopardise wider support for other tobacco control measures, critically including the active support of many smokers" he says. 

Collins thinks the smoker's licence would stigmatize smokers and "shift attention away from the tobacco industry", which he believes is the driving source of the tobacco epidemic. He agrees that it is an "historical absurdity" that tobacco products are so easily accessible and not subjected to any purchasing control, but he suggests that other ways of limiting availability should be tested, rather than targeting the smokers. Collins says "Marketing control is already generally strong in Europe, but plain packaging would constitute a massive step forward. Beyond that (...) there is a need for blue skies thinking".



Second-hand smoking: the invisible killer
But are ideas like the smoker's licence that radical when we consider the health consequences of smoking not only for smokers, but non-smokers as well? Over half a million non-smokers die every year from exposure to second-hand smoke. Smoking bans in public spaces were designed to protect passive smokers but measures like this might not be enough. A survey done in 2006 by the Australian Institute of Health and Welfare revealed that smokers are less likely to agree that second-hand smoking causes health problems, even though it is well-established that second-hand smoking causes heart disease and lung cancer in non-smoking adults, and respiratory diseases in children. This unawareness of the dangers of second-hand smoking puts non-smokers at risk, children in particular.

A study published in the December issue of Pediatrics on 795 smoking parents reports that although most parents restrain from smoking in the house, about 70% smoke in the car, and nearly half of these smoke in the car when their children are present. Research shows that the air quality inside a car when someone is smoking with a window opened is similar to that of a smoky bar. A few countries like Australia, South Africa and Canada have recognised this problem and started implementing laws interdicting smoking in vehicles carrying children specifically to protect children from second-hand smoking, but in most countries this problem seems largely ignored.

The beginning of the end?
Tobacco continues to kill millions around the world but it is not all bad news. Most new cars don't have ashtrays or cigarette lighters, and crystal ashtrays are no longer a traditional item in wedding lists. These are signs that smoking is no longer a glamorous or ordinary affair, and at least in developed countries, these cultural changes are here to stay.

And there is more good news. Recent research shows that the health benefits of quitting smoking are even greater than previously thought. For instance, a new study led by researchers at Oxford University on over 1.2 million women shows that women who stop smoking before middle age can live up to 10 years longer than those who continue smoking. And even those who stop smoking later in their lives have about 50-70% less risk of developing smoking-related diseases and dying prematurely, and these results confirm previous studies performed in men.

The first smoking bans on airplanes 15 years ago caused public uproar. About ten years later, the introduction of smoke-free laws in indoor public spaces also caused intense public debate. Perhaps society is not ready for a smoker's licence yet, but maybe in a decade or two, just as we now deem smoking on airplanes absurd, we will condemn how purchasing and consuming tobacco products was once as easy as breathing air.

Image credits: FreeDigitalPhotos.net

References:
Levy, D., de Almeida, L., & Szklo, A. (2012). The Brazil SimSmoke Policy Simulation Model: The Effect of Strong Tobacco Control Policies on Smoking Prevalence and Smoking-Attributable Deaths in a Middle Income Nation PLoS Medicine, 9 (11) DOI: 10.1371/journal.pmed.1001336 

Chapman S. (2012). The Case for a Smoker's License, PLoS Medicine, 9 (11) e1001342. DOI:  

Collin J. (2012). The Case against a Smoker's License, PLoS Medicine, 9 (11) e1001343. DOI:  

Nabi-Burza E., Regan S., Drehmer J., Ossip D., Rigotti N., Hipple B., Dempsey J., Hall N., Friebely J. & Weiley V. & (2012). Parents Smoking in Their Cars With Children Present, PEDIATRICS, 130 (6) e1471-e1478. DOI:  

Pirie K et al. (2012) The 21st century hazards of smoking and benefits of stopping: a prospective study of one million women in the UK. The Lancet. DOI: 10.1016/S0140-6736(08)61345-8

Tobacco in Australia: A comprehensive online resource
http://www.tobaccoinaustralia.org.au/

This article was published in The Munich Eye on 7-12-12. You can read it here.

21 Nov 2012

Brain waves used to create music


Science and art often go hand in hand. M.C. Escher played with geometry in his famous prints of impossible realities, and anatomist Gunther von Hagenst captivated millions of people with a display of preserved human corpses and body parts. More recently, a popular installation at the London Barbican Gallery offers art lovers the unique experience of walking in the rain without getting wet. 

Science lets art push boundaries, and so is increasingly used by modern artists to shock and awe. But this is a two way street.

Researchers from the University of Electronic Science and Technology in China have now used recordings from brain scans to create music, and they hope that listening to the brain will give new insights into how it works.

EEG-fMRI music from two subjects (Credit: Lu et al 2012 PLoS ONE)

This unusual way of blending science and art was first introduced in 1965 by the American composer Alvin Lucier in the piece Music for Solo Performer, but it was not until the 1990s that 'brainwave music' boomed with the development of powerful computers. Scientists and musicians now use computational models to convert data from brain scan technology into music played by electronic synthesizers.

In the new study published in PLoS ONE, Jing Lu and colleagues developed a new method to combine readings from electroencephalograms (EEGs) and functional MRI (fMRI) brain scans to produce music that better mimics contemporary classical music. The amplitude and the frequency of the EEG signal were used to create the pitch and the duration of each musical note. This was then remixed with an fMRI signal, which set the intensity of the notes played. 

Functional MRI imaging (Credit: Wikipedia)

The authors acknowledge that the sources of the two signals are however unrelated. "There is something a little arbitrary about putting EEG and fMRI together in this way" says philosopher Dan Lloyd from Trinity College, Connecticut, who was the first person to create music from fMRI scans. "But you have to start somewhere, learning scales before you play a sonata, and this is a good start" he adds.

EEGs measure the electrical activity of the brain. Brain cells, or neurons, communicate with one another through electrical signals. During an EEG, electrodes are attached to the scalp and plugged into a computer that converts the electrical signals to waves. EEGs are currently used to diagnose epilepsy and sleep disorders for instance.

fMRI, or functional magnetic resonance imaging, on the other hand measures brain activity by detecting changes in blood flow, and is mostly used in research. Neurons need oxygen to make energy, so when a brain area is more active, oxygen-rich blood surges. The pattern of brain activity across the brain is then represented in a color code.

The authors of the study plan to improve their EEG-fMRI method so it may be used for clinical diagnosis, for example, if the music could produce audible differences between healthy and sick brains. Lloyd says

"With the proper sonification [conversion to sound], something like a 'brain stethoscope' could be developed as a clinical tool for detecting clues to a variety of brain conditions". 

But there are skeptics. David Sulzer, a neurophysiologist at Columbia University and jazz musician, thinks that brainwave music can only detect very significant changes in brain activity, such as an epileptic seizure. He says "If you cannot diagnose an illness through a chart recorder readout, I do not understand how it can be done sonically". 

Sulzer believes music made from brain activity is an art and a science didactic tool. For instance, he uses The Brainwave Music Project to teach the public about brain function before his performances of brainwave music.

Whether brainwave music will be useful for science or medicine remains an open question, but it can surely be said that it has become an art form of its own. It might not be for everyone's taste but brainwave music certainly causes an impression, which is the very definition of modern art.

Source: 
Lu J, Wu D, Yang H, Luo C, Li C, et al. (2012) Scale-Free Brain-Wave Music from Simultaneously EEG and fMRI Recordings. PLoS ONE doi:10.1371/journal.pone.0049773

Listen to the authors' EEG-fMRI brainwave music here and here.

This article was published in The Munich Eye on 22-11-2012. You can read it here.


20 Nov 2012

Bacteria make living electric cables


At the bottom of the ocean, there is a strange world of microbes thriving in mud sediments. They all strive toward the same vital goal of using oxygen and available nutrients to produce energy for growth, so competition is fierce.
The bacteria on the seabed surface are the lucky ones, as they can readily take up oxygen from sea water. But a couple of centimeters below oxygen is scarce, and bacteria buried deep into the mud need to come up with more ingenious ways to gain energy.
Bacteria cables in the sea bed mud
(Credit: Mingdong Dong, Jie Song and Nils Risgaard-Petersen) 

In a new study published in Nature, a research team led by Nils Risgaard-Petersen and Lars Nielsen at Aarhus University in Denmark, shows how some bizarre bacteria employ a cunning trick to both feed from nutrients in deep marine sediment and consume oxygen at the surface: they function as living electric cables.

A couple of years ago, the team made the astonishing discovery that electric currents linked oxygen consumption at the top sediment layers with hydrogen sulfide at the bottom, more than a centimeter away. "The identity of the electron conductor has however been an enigma" Risgaard-Petersen says.
The scientists postulated that bacteria could work together to conduct these electric currents through a network of tiny hair-like appendages called nanowires. However, evidence so far shows that bacterial nanowires can only transfer electrons over shorter distances, so this alone could not explain the intriguing results.
To solve this riddle, Risgaard-Petersen and colleagues collected samples of marine sediment from Aarhus bay and carefully scrutinized the top sediment layers. In a true eureka moment, they found tufts of entangled centimeter-long filamentous bacteria. "Before us nobody had hypothesized about its existence, so nobody had looked for it" says Risgaard-Petersen.
The filaments of bacteria stretch between the top and bottom sediment layers
(Credit: Nils Risgaard-Petersen)

The filamentous microbes turned out to be new members of the Desulfobulbaceae family, which includes bacteria capable of consuming hydrogen sulfide in deep sediment zones. This seemed like a good indication that these long bacteria filaments could be mediating the flow of electrons across distant sediment layers. Indeed, when the scientists cut the filaments, the electric currents stopped and the consumption of oxygen and hydrogen sulfide plunged.
"Risgaard-Petersen and collaborators linked the presence of bacterial filaments to the electrical coupling of the oxygen and sulfide layers in marine sediments, which are typically separated by millimeter to centimeter distances" says Gemma Reguera, a microbiologist from Michigan State University specialized in the study of sediment bacteria "These [distance] scales truly defy our current knowledge of biological electron transfer".
Each filament consists of many bacterial cells lined up in a long chain and surrounded by a shared outer membrane. Interestingly, this outer membrane has uniform ridges filled up with charged material running along the entire length of the filament. The authors of the study believe these ridges could be 'internal insulated wires' for driving the electron flow across sediment layers. However, these molecular details remain unclear.
A cross-section of four cable bacteria viewed with an transmission electron microscope
(Credit: Karen Thomsen)

Derek Lovley, an expert on electromicrobiology at the University of Massachusetts thinks that discovering the source of this 'potentially conductive material' is crucial. "As with the initial studies with [bacterial nanowires] there will be skeptics because they have not been able to measure long-range electron transport directly" and adds "It will be interesting to watch this story unfold."
More than tens of thousand kilometers of filamentous bacteria live in a single square meter of mud from the undisturbed seabed, so it is possible that this type of long-distance electron transport could be widespread in nature. The long filaments are however very fragile, and small disturbances such as sea waves could lead to 'fatal cable breakage'. Eric Roden, an expert on biogeochemistry at the University of Wisconsin notes "Whether or not such filamentous networks are actually present and active in natural sediments, where all sorts of mixing processes and other disturbances are common, remains to be determined".

Since the discovery of bacterial nanowires, several research teams have explored their potential biotechnological applications, for example, in bioelectronic devices or for electricity generation from renewable sources, such as waste. Could the filamentous bacteria potentially be used for technology development?

"We need to know more about how current is transported inside these organisms" explains Risgaard-Petersen "but perhaps there is a possibility to grow electric conductive structures for use in electrical devices".

This article was published in The Munich Eye on 26-10-2012. You can read it here.

Source:
Pfeffer, C. et al. Nature (2012) http://dx.doi.org/10.1038/nature11586


13 Nov 2012

Music lessons in childhood benefit adult brain


Parents may have found a new reason to encourage their children to play a musical instrument. A new study led by scientists at Northwestern University reports that musical training during childhood can have positive effects on the adult brain, even if the training only lasts a few years.                        

Credit: everystockphoto

As children return to school, many parents face the question of whether to enroll their child in music lessons. They don't want to overload their child with extracurricular activities, but they are also afraid of missing the age window when musical talent can be discovered and nurtured. Besides, an investment in music lessons might be fruitless if the child stops playing the musical instrument at a later age. Yet scientists now argue this is not the case.

Research on professional musicians shows that musical experience can not only rewire the auditory system, but also improve several of the brain's functions, such as motor control, memory and verbal ability. However, it had never been investigated whether these positive changes in the brain persist if the musical training stops before adulthood, which is indeed the case for most people who engage in music lessons at a young age.                        

In a new study published in August in the Journal of Neuroscience, scientists test healthy adults who started playing a musical instrument at around 9 years of age but stopped a few years later. They used a technique called Auditory Brainstem Response (ABR), which measures brain activity after auditory stimulation, a similar test to the one used to assess whether newborn babies can hear. The scientists then performed the same experiments on adults who have never played an instrument and compared the results. 

'We find that the adult brain profits from past experiences with music. This is the first study to focus on whether the effects of music are long-lasting and whether they persist after the child stops playing an instrument' explains Erika Skoe, leading author in the study.          

The authors of the study propose that these long-term positive changes in the brain could be a result of the active interaction with sound that occurs when playing a musical instrument. 'Playing a musical instrument is an incredibly active process that engages all of the senses, not just hearing. Active engagement with sound appears to be the critical ingredient for promoting long-lasting neural changes' says Skoe. This could explain why passive exposure to an enriched auditory environment alone only produces a temporary enhancement of brain activity, a phenomenon that has been observed in rat models. Referring to these experiments Skoe explains 'An enriched auditory environment was more or less "background music" in the animal's environment and not something that they could directly interact with.'

So when should children start learning music in order to benefit from these long-lasting neural changes?

'Our study suggests that long-lasting effects can be seen with just one year of music lessons during grade [primary] school. However, music is likely to be a positive force on the brain at any age. Because every child is different, we are cautious about interpreting our results too prescriptively' answers Skoe.

This and other studies raise the debate of whether or not music lessons should be compulsory in state schools. Nina Kraus, head of the Auditory Neuroscience Laboratory where the present study was conducted says 

'I think musical training can do tremendous good (beyond music) in developing a better learner. Musical training strengthens auditory-based communication and learning skills including hearing speech in noisy situations, reading, auditory working memory, and auditory attention.' 

From this elegant research we learn that playing a musical instrument during childhood has long-lasting positive effects on the brain. And the good news for parents is, that children will benefit from their music lessons throughout their adult life, even if they decide to swap the violin for a surfboard in their teens.

This article was published in The Munich Eye on 7-10-2012. You can read it here.

Source:
Skoe E. and Kraus N. Journal or Neuroscience (2012) DOI: 10.1523/JNEUROSCI.1949-12.2012



9 Nov 2012

Lung-on-a-chip: a human disease model that could revolutionize drug discovery


Scientists used a microchip that recreates a breathing lung to study pulmonary edema and test a new drug against this life-threatening disease, raising hopes that this organ-on-chip technology could speed up drug development and replace animal testing.

The lung-on-a-chip is the size of a memory stick and is made of a clear silicone rubber
 (credit: Harvard University Wyss Institute)

The lung-on-a-chip was first developed by Donald Ingber's team at the Harvard University Wyss Institute two years ago using technology from the computer microchip industry. The microdevice mimics the tiny air sacs in the lungs where gases are exchanged between the air we breathe and the blood.
 
About the size of a memory stick, the plastic microchip contains two chambers separated by a thin leaky membrane. This flexible membrane has living lung cells with air flowing through them stuck on one side, and blood vessel cells immersed in fluid on the other. Gases or fluids can be transferred across the membrane between lung and blood vessel tissues.
 
The membrane and attached cells are stretched and relaxed by a vacuum system in the same way as an air sac during breathing movements.

Now, in a study published this week in Science Translational Medicine, the Harvard scientists used these microchips to mimic pulmonary edema, showing for the first time that organs-on-chip can be used to model human disease. 

Pulmonary edema is the abnormal buildup of fluid in the lung air sacs, which leads to respiratory failure and if left untreated can be fatal. The most common cause of pulmonary edema is congenital heart failure, but it can also occur as a side effect of some drugs. 

In this study, the researchers used interleukin-2 (IL-2), a chemotherapy drug with severe side effects, to recapitulate pulmonary edema in the lung-on-a-chip. Injection of this drug into the microchip blood chamber triggered fluid leakage across the membrane into the air space, recreating what happens in the lungs of human patients treated with IL-2.

A chemotherapy drug recapitulates pulmonary edema in the microchip
 (credit: Harvard Institute Wyss Institute)
 
But there was a surprising result: the physical action of 'breathing' aggravated fluid leakage into the air chamber. IL-2 causes cell connections to break, which opens holes in the tissues. It turns out that the mechanical strain of the breathing motion dramatically increases the size of these holes. 'This truly changes the way we view this disease process, as well as how we might treat this type of condition' says Ingber.

This unexpected finding led the team to test an experimental drug developed by GlaxoSmithKline (GSK) which blocks a protein involved in controlling tissue mechanical tension. They found that the drug 'fully prevents the IL2-induced edema response'. In a collaborative study, a GSK research team led by Kevin Thorneloe showed that the drug curbed pulmonary edema symptoms caused by heart failure in animal models, confirming the lung-on-a-chip results.
 
Drug development is a long and costly process that currently relies on animal testing, and more often than not drugs that perform well in animal models then fail in the human clinical trial stages.
 
'Major pharmaceutical companies and government funding agencies are now beginning to recognize a crucial need for new technologies that can quickly and reliably predict drug safety and efficacy in humans in preclinical studies' says Ingber.

Human cells cultured in a three-dimensional matrix are widely used to test drug toxicity but they lack the complex properties that define organs, such as tissue-tissue interactions or mechanically active environments. Organs-on-chip could be the solution to this problem.
 
'Our finding that breathing motions are critical to mimic the IL-2 toxicity response is a clear example of how this could not be done with conventional culture models' says Ingber.

In the past years several groups have built organ-on-chips that mimic lung, kidney, heart and other organs, but this study is the first to model a human disease and to successfully test a drug in a microchip. Shuichi Takayama, an expert on biomedical engineering at the University of Michigan says
 
'This study demonstrates that this type of technology is promising for replacing animal models in some aspects of drug screening and testing.'

However, the organ-on-chip technology is in its early stages and Ingber believes 'animal models will be around for a long time'.

'The goal is to develop organ chip replacements for one particular animal model at a time, and hence, slowly shift the emphasis away from animal models. This would represent a major advance in the pharmaceutical field, and have great implications for testing of chemicals, toxins and cosmetics as well' he says.

This article was published in The Munich Eye on the 9-11-2012. You can read it here.

Source:
Huh et al Science Translational Medicine (2012) DOI: 10.1126/scitranslmed.3004249


3 Nov 2012

Promiscuous female guppies have the upper hand


New research shows that mating with multiple partners brings benefits for females. In a study published in September in the journal BMC Evolutionary Biology, scientists report that promiscuous female guppies are more fertile than singly mated females.



Female and male Trinidadian guppies
(credit: Biodiversity and Behavioural Group at University of St Andrews)


For evolutionary biologists, it is obvious why male promiscuity has selective advantages: mating with several females gives males more chances to fertilize eggs and produce viable descendants. However, female promiscuity, or polyandry (poly- many, andras- male), still stirs a debate in the scientific community, because it doesn't bring any apparent benefit for the females. On the contrary, multiple mating can come at a high cost. Besides consuming time and energy, multiple mating exposes females to predation, disease and physical harm from males. Female polyandry is nonetheless widespread in nature, and growing evidence shows that choosing to mate with several partners seems to be the rule, rather than the exception in a wide number of species, from invertebrates to birds, reptiles and even some mammals. 



So why do females prefer to mate with multiple males? Scientists believe that polyandry might have indirect genetic benefits for the females, ensuring the 'good genes' pass on to the next generation. For instance, in some species the offspring of promiscuous females is better adapted, and hence produces more grandchildren for the female, than ofspring from single mated females. However, in the study performed by Anne Magurran's team at the University of St Andrews in the UK, the researchers found that, unexpectedly, multiple mating brings direct benefits for females. 



The scientists performed controlled experiments in the laboratory with wild caught guppies from the Lower Tacarigua River in Trinidad. They placed about 80 females in individual tanks and then allowed them to mate either with a single male, or with multiple males. They carefully followed these guppies for two generations, keeping count of the number of children and grandchildren they produced. They found that promiscuous females had more offspring, but there was no difference in their size, growth rate or viability, when compared to offspring of single mated females. Miguel Barbosa who led the study says 'The surprise came when the results showed that the benefits of multiple mating were achieved through an increase in female fecundity rather than by increasing offspring viability/attractiveness, as expected.' 



Previous research showed a similar increase in fertility in promiscuous females of other species, but this is the first study where both direct and indirect benefits of multiple mating are investigated over two generations. But why is there an increase in fertility in multiply mated females? Barbosa explains 'The presence of sperm from multiple sources/fathers reduces the risk of genetic incompatibility, but also promotes sperm competition. Both can contribute to the increase in fecundity reported in our study.' 



Another surprising finding in this study was that promiscuous female guppies had more sons, and scientists believe this accounts for the larger number of grandchildren. 'There was 60% more sons produced by multiple mated females than produced by single mated ones' says Barbosa. This is the first evidence that female multiple mating influences the offspring sex-ratio in guppies, but the scientists, however, still don't understand what causes this overproduction of males. 



Tommaso Pizzari, an evolutionary biologist from the University of Oxford in the UK, says 'The present study offers experimental evidence suggesting that female promiscuity might be associated with some net fitness benefits to the female (...) These results contribute to shed light into a major evolutionary puzzle: namely, why do females mate with multiple males when often one insemination is sufficient for fertilization and mating is costly.'

This article was published in The Munich Eye on 02-10-2012. You can read it here.

Source: 
Barbosa et al. BMC Evolutionary Biology (2012) DOI: 10.1186/1471-2148-12-185