FR
EE
SYNAPSE THE SCIENCE MAGAZINE WRITTEN BY STUDENTS FOR STUDENTS
ISSUE 10 - March 2015
The
University of Bristol
Edge of Existence The Mystery of
Ball Lightning Synapse Strips
EDITORIAL
The Team Rosie Hayward Editor in Chief
Thien Ho
Vice President
Amy Newman
Secretary & Senior Editor
Louisa Cockbill
Treasurer & Senior Editor
Nick Henden
Chief Graphic Designer
Jake Ayres
Graphic Designer
Melissa Levy
Welcome to
SYNA PSE Science Magazine
The 10th issue of Synapse Science Magazine is here and as ever it is full of articles covering a range of scientific news and ideas. This issue explores the mystery of ball lightning, the edge of the Universe, the Fermi paradox and even our very first comic strip! Synapse is written for students, by students, and anyone can join in: all you need to do is join the society on the UBU website. If you are interested in writing, editing, graphic design, photography or even recording scientific radio podcasts email us at:
E: synapsebristol@gmail.com
Toby Benham
Managing Editor
Mutanu Malinda
Media Co-Director
Tom Stubbs
Media Co-Director
Daisy Dunne Senior Editor
Felicity Russell Senior Editor
Editors
Managing Editor
Stephanie Bates Sophie Groenhof Becca Jew Jade Low Rachel Greenwood Hayley McLennan Katie Porter Hugo Scharfenstien Isa Viegelmann Ines Wood
Synapse wishes to acknowledge the support of the 2 | SYNAPSE
Guarantors of Brain.
CONTENTS
Killer Communicators What the Environment does for Us Autism and Anorexia Nervosa: Is there a link?
4 5 6 7 8
The Edge of Existence The Bat Man of Mexico Looking Back: Why looking back may be the way forward
Innovating Against Climate Change Homing Instinct Lend Me A Signal!
10 12 13 14
Solving the Fermi Paradox
Is Your Immune System Bored? The Mystery of Ball Lightning The Secret of the Wild Mouse Lemur
16 18 19
Venom:
20
Synapse Strips
22
The Latest Cure for Cancer and HIV?
synapsebristol.blogspot.co.uk | 3
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Killer Communicators A
ccording to new research killer whales can learn to ‘speak dolphin’. Three captive killer whales at SeaWorld were found to alter their vocal repertoires to match those of bottlenose dolphins when socialised with them, suggesting both vocal learning and inter-species communication within these cetaceans (the order containing whales, dolphins and porpoises). This research was carried out by Whitney Musser, a San Diego graduate student and Dr Ann Bowles, senior research scientist at the Hubbs-Seaworld Research Institute, and was recently published in the Journal of the Acoustical Society of America. Vocal learning is a rare skill in the Animal Kingdom as the vocal sounds produced by most species are innate (inherent as opposed to learned). However, a small number of animal groups exhibit vocal learning, including humans, bats and certain birds such as parrots and hummingbirds. The capacity to learn new vocal sounds is of great significance suggesting a high level of neural plasticity, which is associated with higher intelligence and brain complexity. Killer whales and dolphins both communicate using a combination of pulsed calls, clicks and whistles,with killer whales using mainly pulsed calls and dolphins predominantly using clicks and whistles. When kept with bottlenose dolphins, the three killer whales used in the study adapted their vocal range to primarily use clicks and whistles whilst
4 | SYNAPSE
Photo by Rachel Baxter
using significantly fewer pulsed calls. One of the whales could even mimic a series of calls that the dolphins had been taught by their trainers before being introduced to the whales. The fact that these cetaceans have the ability to learn new vocal sounds and communicate between species could be essential to their survival as they currently face a variety of threats such as habitat shrinkage, climate change, pollution and entanglement in fishing nets. Successful communication and social organisation could be necessary for survival in an ever more hostile environment. Although this piece of research has extended our knowledge of vocal learning among cetaceans, it has been incredibly controversial. This is because the study used captive whales and dolphins at SeaWorld, an organisation that has been heavily criticised recently due to exposure of the suffering experienced by its resident marine mammals. The unnatural habitat and lack of space provided by SeaWorld causes the whales and dolphins to suffer huge amounts of stress, affecting their health and significantly shortening their lifespans. Therefore, this research is seen as unethical and does not necessarily represent vocal learning in wild whales and dolphins. However, it does make a step towards fully understanding social interaction and learning amongst the cetaceans, which is key to comprehending communication and vocal learning within the animal kingdom.
Rachel Baxter
W
hen you turn on a tap, drink a cup of coffee, or enjoy a walk in the countryside, you should give thanks to ecosystem services. These are the environmental processes that provide us with clean air and water, food, and other materials. They also provide less tangible things such as recreation, aesthetics, and spiritual experiences. The water you use is filtered through a watershed, the coffee you drink is pollinated by bees, and the beautiful views you see are part of the natural landscape. Ecosystem services are a popular concept in ecology, and we are now trying to put a monetary value on the things we gain from the environment. There are different ways of classifying ecosystem services, depending on how we use them. Provisioning services are those products that are essential to our survival and wellbeing, such as clean water and air, food, and medicine. These services are easy to value as they are already commercial products. Regulating services are considered by some to be the most important, and include climate regulation, pollination, and natural pest control. These services are thought to be so important because they are irreplaceable, for instance, we would not be able to regulate the climate of the entire planet artificially. Supporting services enable other services to function, for example, soil is needed to grow crops. The plants that grow in the soil also help to prevent erosion with their roots. The remaining group of services includes those that enrich our lives in a cultural or even spiritual way. Many of us enjoy being outdoors, and the maintenance of historical landscapes is especially
ARTICLE
What the Environment does for Us
important for indigenous people to continue to lead traditional lifestyles. These services are probably the most difficult to value. Biodiversity is an important component of ecosystem services that is often overlooked. Many services would not function correctly without a multitude of different species of plants, animals, and microbes interacting with each other. As the extinction rate rises, we must be able to identify those species that are essential to ecosystem services and perhaps provide them with increased conservation measures. It should come as no surprise that ecosystem services are under threat, particularly from changes in climate and land use. The Millennium Ecosystem Assessment reports that approximately 60% of the 24 ecosystems evaluated are being degraded or used unsustainably. However, there is hope in the form of positive synergies. These are practices that conserve a particular ecosystem service that then benefits others. For example, urban parks provide a recreational service, benefit wildlife, and act as a carbon sink. The clever application of some services could provide solutions to many problems. For example, the cost of air conditioning could be reduced just by planting shade trees around a building. So keep in mind everything the environment does for us, even the things you might not have noticed before. If we don’t protect ecosystem services, from clean water to parks, we will definitely miss them when they’re gone.
Jessica Towne
synapsebristol.blogspot.co.uk | 5
ARTICLE
Is There a Link Between Autism and Anorexia Nervosa?
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emales with anorexia have elevated autistic traits” was the conclusion made by researchers from Cambridge University who conducted a study on 66 female adolescents struggling with this eating disorder. The significant research findings may result in improving treatment methods of those who suffer from anorexia nervosa. Anorexia nervosa is an eating disorder, mostly prevalent in young females. The sufferers develop an exaggerated anxiety about their body shape, resulting in behaviours such as restricting the amount of food consumed, excessive exercising and self-induced vomiting. The patient refuses to maintain their minimum body weight. Autistic Spectrum Disorder is a condition which causes problems with social interaction, such as struggling to understand other people’s emotions and difficulty in starting conversations. It is also common for autistic individuals to display repetitive patterns of thought, rigid attitudes and fascination for detail and systems. Until now, it has been extensively acknowledged that autism (including Asperger’s syndrome) is more likely to affect males than females. However, researchers admit that current understanding of the disorder is incomplete and requires more knowledge regarding its underlying causes. The above-mentioned study proved that patients with anorexia nervosa had significantly higher SQ (systemising quotient) and lower EQ (empathizing quotient) than control subjects, meaning anorexic patients expressed greater passion and
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drive to explore and construct systems rather than being interested in and understanding the feelings of others compared to other female control subjects. Interestingly, such results are more common in males than females, hence showing that girls with anorexia display an anomalous, ‘masculinized’ cognitive profile. It has been suggested that anorexic females direct their systemizing towards the food intake domain, focusing in high degrees of detail on the relationship between food intake and body weight. If the obsession with systems was directed at a different focus, in theory the girls’ behaviour would not necessarily have resulted in anorexia. The fact that the anorexia patients displayed lower empathy is believed to be manifested in their obsession with self-image rather than other people’s emotions. These results showed that anorexic girls display above-average numbers of autistic traits. Nevertheless, there have been several limitations in the study including the fact that it relied on questionnaires instead of performance measures, and the possibility that the self-focus and withdrawal of anorexic females was a result of starvation. It was therefore recommended that the research should be continued on a wider scale, as understanding the thinking of anorexia nervosa patients could lead to substantial improvements in current treatment approaches and potentially be life-saving. For more information:
Marta Plaszczyk
http://goo.gl/qS7pfE
ARTICLE
W
hen people imagine an edge, they envisage a point at which something stops. But when applied to our universe, can the same argument be made? The observable universe is what can be seen; a sphere of space centred on you. Given that light, the fastest thing in the universe, has a finite speed limit, we can only see as far as light has travelled since the big bang. If you imagine standing at the centre of a sphere of space, the sphere’s surface is the edge of the observable universe. But the observable universe isn’t the entire universe; it is only what we can see. So we perceive it as an edge, when in fact we do not know if one exists. The big bang is usually thought of as an initial explosion of a dense point of matter into space. However, the idea of a ‘bang’ is a common misconception, and the universe did not explode into existence as we imagine it. Instead inflation occurred at every position in space, which was initially a singularity. This means that the big bang happened everywhere; not in a central location. So everything you see when looking into the night sky, all originated from one point.
The universe is expanding at an ever increasing rate. This begs the question, if the universe is expanding, what is it expanding into? When we imagine an object’s edge, there exists something past the object. Applying this to the case of the universe, what exists beyond it? If the universe is expanding, it expands into the beyond. But the universe isn’t like an object. It’s not the stuff inside the universe growing away from each other, but the actual space itself which is expanding. And the universe might not have an edge; to our best current knowledge the Universe appears to be infinite. This means there is no edge! There are many hypothesised endings to the Universe, but the most likely is that the Universe’s expansion will continue, until the remaining dead stars split off from their resident galaxies. Even black holes, cosmic objects with great longevity, are expected to decay over time too, losing energy through the emission of Hawking radiation. So the universe is expanding everywhere, and nobody knows its exact destiny. So what is our fate, will we find the edge?
Laura Rogers & George Thomas synapsebristol.blogspot.co.uk | 7
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The Bat Man of
Mexico
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r. Rodrigo. A. Medellin came to the Bristol Life Sciences building on Monday 20th October to present a Departmental Research Seminar entitled ‘How to do bat conservation, implement it, and not die trying’ and I was lucky enough to be able to attend. Dr. Rodrigo. A. Medellin is an eminent research scientist who is a Professor of Ecology at the Institute of Ecology, University of Mexico. He is currently President of the Society for Conservation Biology and CoChair of the Bat Specialist Group of IUCN (the International Union for Conservation of Nature). Dr Rodrigo has also held a number of important positions in the past, such as being Vice-Chair of the CITES (the Convention on International Trade in Endangered Species) Animals Committee for ten years and he has won a host of international awards. Dr Rodrigo is a part of PCMM, which is a programme for the conservation of bats in Mexico. Bats are the group of mammals typically least considered in conservation plans. There are 138 different species of bats in Mexico, which live in approximately 30,000 caves over an area of 2 million km2. As this is such a large region it is virtually impossible to monitor all of the caves, so the PCMM chose focal species, with 21 migratory, 15 endemic and 21 at risk species being selected. The PCMM has a three pronged intertwined action
8 | SYNAPSE
plan: conservation, environmental education and research. In terms of conservation the PCMM help to stop vandalism and the destruction of habitat, promoting legal and actual protection of caves that are identified as priorities. The PCMM also have an educational focus, with activities and educational materials available for children and adults living near areas, both rural and urban, where bats are prominent, so that people lose the fear they feel toward bats and become more aware of the benefits which they offer. This encourages local people to actively participate in the conservation of bats. After lobbying, the PCMM has achieved a compulsory section about bats in the national school curriculum, which will ensure a greater understanding of bats among young people. Research is very important in being able to implement successful conservation schemes. The PCMM explore which species and how many individuals are in the caves, when and how they reproduce, what they eat and their migration patterns. During his talk, Dr Rodrigo also spoke about a piece of research into the role which bats play in seed dispersal. There is an ongoing defaunation crisis where forests are emptying of large-bodied vertebrates because they are killed as bush meat. Many of these vertebrates would have been seed dispersers of large seeded plants.
Bats are usually associated with small seed dispersal. However, Dr Rodrigo’s research found otherwise.
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bats may play a crucial role in mature and secondary forest dynamics
He was looking at tent-making bats in the Sarapiqui Basin in Costa Rica which are an abundant species in this area. They chew along the main vein of a banana leaf to form an inverted-V-shaped shelter to roost under. This “tent” provides shelter from sun, wind and rain. The researchers noticed that there were lots of seeds under the tents. They carried out a study where they counted and measured the seeds in a 1-m area under the tent in question and then repeated this in four randomly chosen 1-m areas not under tents. They then repeated this process for many tents. The data they gathered showed that the seed density under tents was higher under tents than not with 7.87±12.5 for under the tents and only 0.65±0.5 in the randomly selected areas of the forest. The seed range under the tents was highly diverse, with seeds coming from at least 44 species of plant that had seeds larger than 1-cm in length. The conclusion from this is that tent-making bats must eat the fruit and then drop the seeds. This means bats may play a crucial role in mature and secondary forest dynamics, especially in “empty forests” where the number of large vertebrates is greatly reduced. These findings could help secure additional funding and convince governments of how important bats are within ecosystems.
“
Anna Pope synapsebristol.blogspot.co.uk | 9
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Why Looking Back May Be The Way Forward
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n all walks of life, but particularly in science, we are marching inexorably forwards at a rate almost unmatched by any other point in history. Daily, research that was at one point groundbreaking is replaced by something shiny and new. This isn’t a bad thing, far from it. Indeed, it is why I find science such an exciting field to be involved in; we are constantly discovering new things and improving our understanding of the world in which we live. One unfortunate side effect of this culture of novelty and progress is that the merits of ‘old’ research can be cast by the wayside. It is encouraging, therefore, that the solutions to some of our seemingly unsolvable problems can be found residing in the long-abandoned archives of medical research. The best example of turning to established research to solve a persistent problem is the search for HIV therapeutics. HIV, the virus responsible for the AIDS epidemic, has proved a resilient foe for medical research to face. The search for an efficacious HIV vaccine has yielded nothing and while the therapeutics being produced are pretty good, they can always be better. One of the key targets in the treatment of HIV is the viral protease, an enzyme
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that cuts up the viral pre-cursor proteins, allowing progeny virions to mature and infect further cells in an infected individual. One of the first tasks when targeting protease was, as it often is, to determine its crystal structure (shown in Fig. 1). Upon doing this, it was determined that it had a similar structure to Renin, an enzyme that mediates extracellular volume and vasoconstriction, thus mediating the body’s main arterial blood pressure. Using this knowledge, the first generation of HIV protease inhibitors were based on the many Renin inhibitors that already existed, to treat hypertension. While the protease inhibitors came early in the timeline of HIV research, there are a number of similar examples still at the forefront of HIV therapeutics research. One of these is the potential use of ribozymes as anti-HIV drugs. Ribozymes are RNA molecules that are capable of catalyzing specific biological reactions. Their discovery showed that RNA can act both as genetic material, like DNA, but also as enzymes, giving them a far wider range of roles than first thought. One of the main processes catalyzed by ribozymes is the cleavage and removal of exons from pre-mRNA, thus converting it into mature mRNA from which proteins can be synthesised.
Figure 1 Determining the structure of the HIV protease allowed researches to pioneer the use of Reninlike inhibitors in the treatment of HIV
In a fine example of using ingenuity to connect two seemingly unrelated subjects, there is now great excitement about the use of ribozymes to treat HIV. The basis for the hypothesis? Since ribozymes can cut up RNA and HIV has an RNA genome, can ribozymes be targeted against the HIV genomes, destabilising them and destroying the virus? That is precisely the thought behind a trial that is currently in Phase II testing, which uses gene therapy to introduce a gene coding for the OZ1 ribozyme. This would potentially be a one-time cure and is showing good preliminary results, with viral load far lower in those that received the ribozyme.
These examples show just how important it is, despite the exciting times in which we are working, to remain aware of the work that has been done before. A new development in a field doesn’t always have to mean a brand new product. With the wealth of knowledge that the science community has already accumulated, we could well be sitting on a gold-mine of potential solutions to the problems posed by our most fiendish foes.
Joe Connor synapsebristol.blogspot.co.uk | 11
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Innovating Against
Climate Change
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ocated on the Tropic of Capricorn, Australasia is the world’s driest inhabited continent. While clear blue skies may sound enviable, dry conditions can prove problematic for larger settlements with high water demands. The city of Perth sustains nearly two million people on the south west coast of Australia. However, in the last half century a decline in annual rainfall has been observed. An average annual rainfall of 766 mm from 1990 to 1999 dropped to 656 mm in 2009; dams were depleted and the water supply had to be rethought. This challenge was tackled in several ways. Reverse Osmosis Converting seawater into drinking water, or desalination, has long been popular in the Middle East. Two desalination plants have now been built around Perth, meaning half of the city’s drinking water can be extracted from the ocean. Kwinana desalination plant just south of Perth turns water from the Indian Ocean into nearly 40 million gallons of drinking water per day. However this process is expensive and energy intensive. To overcome the energy burden Emu Downs Wind Farm was established. Located three hours north of Perth by car, it possesses 48 wind turbines each as high as a 15 story building. The result is that one million people (half of the population) can be supplied with drinking water by sustainable means from the sea.
Recycling Water In addition, a recent ten year groundwater replenishment trial was very successful and is now in production. This involves sustainable management of the Gnangara groundwater resource: Perth’s largest source of groundwater. The idea effectively involves water being recycled. Treated wastewater is injected into deep aquifers up to one kilometre underground. Sandy soil then acts as a natural filter leading to a source of clean water. Replicating nature by re-using the same material is more efficient and economically advantageous. Conservation The simplest method for protection of water supplies is to simply use less water. However, this is easier said than done. Educating the public, most importantly the future generation, is vital to ensure that water isn’t wasted in the first place. Small changes such as taking showers instead of baths, turning the tap off while brushing teeth and restricting use of hosepipes can have a dramatic impact collectively. Perth proves that this works as its water demand has actually decreased even though the city is growing in population. Their multi-plan strategy provides the city with water security and support for further growth. By conserving water, re-using it and utilising novel technology to extract more, Perth has demonstrated it is possible to innovate against climate change. Let us hope this may provide inspiration to cities across the globe.
Toby Benham 12 | SYNAPSE
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Homing Instinct any humans have a sentimental connection to their birthplace, but other species take it much further. Female sea turtles return to the place of their birth to lay their eggs, a well-observed but as yet unexplained phenomenon known as natal homing. For many turtles this can be twenty to thirty years after their own hatching, and may involve a journey of several thousand miles. One loggerhead turtle was tracked on a seven thousand mile odyssey from Mexico to Japan.
The mechanism for magnetoreception in animals is unconfirmed. One theory is that magnetite (a magnetic mineral used by magnetotactic bacteria) in the form of minute crystals forms permanent magnets that twist into alignment with the Earth’s magnetic field if allowed to rotate freely. This movement may then exert a force on a secondary receptor in the nervous system. Although the evidence for this theory is not conclusive, magnetite crystals have been found in many animals, including sea turtles.
The first and most obvious question is: how can sea turtles find their way back? Research has shown that they can sense the angle and strength of Earth’s magnetic field, even soon after they have hatched. This allows them to know their position relative to the position of their birthplace, and scientists believe that they use this in conjunction with other markers, such as smells, to navigate. As strange as this may seem to humans, who rely largely on the ‘five senses’, magnetoreception has been observed in bacteria and many animals such as bats, mice and pigeons.
The second question is: why? How does it benefit a turtle to use time and energy on going to one specific beach to nest? A recent study in the Cape Verde islands found that turtles from different islands actually possess different immune genes. They therefore pass on to their offspring the correct genes for fighting off local parasites, giving them a better chance of surviving in that area. This suggests that over the course of evolutionary time, sea turtles that returned ‘home’ for nesting have enjoyed a selective advantage over those who did not, to the extent that this is now an innate behaviour. There are many threats to sea turtles, from natural predators to poaching, but due to their natal homing behaviour, beach erosion and coastal armouring are further hazards. Structures such as sea walls can cause turtles to nest further down the beach than they naturally would, increasing the risk of a nest being covered with water, or can prevent them from nesting at all. The more understanding we have of these animals, the more effectively we will be able to protect them and their nesting sites for years to come.
Hayley McLennan synapsebristol.blogspot.co.uk | 13
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Lend me a Signal!
Solving the Fermi Paradox
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he director Stanley Kubrick once quoted Arthur C. Clarke, saying: “Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.” It’s hard to disagree. Is it worse to inhabit a universe where you are the only occupant or one containing something else potentially more intelligent and dangerous than you? It’s a persistently thorny question because we have only one example to work with: ourselves. It’s also surprisingly hard to find other civilisations given how massive the observable universe is. Apparently in 1950 the physicist Enrico Fermi and his colleagues were discussing faster-thanlight travel when he exclaimed “Where are they?!” The paradox he presented lies between the high calculated probability that many extraterrestrial civilisations exist and the lack of evidence for them, a.k.a Fermi’s Paradox, or “The Great Silence”. Later, Dr Frank Drake wrote an equation highlighting the difficulties of finding intelligent life outside the solar system. It included factors like rates of star formation and fractions of planets likely to be inhabited. The estimate for the number of civilisations in our galaxy was 1,000 – 100,000,000. This indicates that there should be intelligent life in
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our astronomical back garden. Even if we couldn’t directly observe them, such civilisations would explore their surroundings as we do. Where are the probes? Where is everybody? There has been a huge effort to comb the skies for something inexplicable by any means but intelligent life. Astronomers look at the atmospheres of exoplanets for gases that could only result from industry or life processes, like methane. Unfortunately because they’re so far away we’re lucky to even see these planets, instead having to infer their presence from the “wobble” they induce in the star they orbit. Current efforts are instead focused on listening for radio transmissions, and one signal has been detected that suggests an artifical source.The “Wow!” Signal was heard coming from near Sagittarius in 1971 and, although it hasn’t been heard since, hasn’t yet been identified as any known natural phenomenon. More speculative is the idea of alien artefacts being found. It’s likely that more advanced civilisations send out probes as we do, so the types we expect to see are hypothetical. One is the Von Neumann self-replicating probe. If one civilisation in the galaxy used this
method, it could explore all the Milky Way’s planets within 5 million years. Others include Bracewell Probes, created solely for information exchange with us. Some astronomers have tried finding and communicating with such devices. Yet more speculative is the idea of Dyson Spheres; enormous structures encircling star systems harvesting solar energy for the resource needs of advanced civilisations. These would alter the outside appearance of the star(s) so it would be fairly obvious if one was found, but the surveys are incomplete. If maths says we should observe evidence of other civilisations, why can’t we? There are many hypothetical reasons. Maybe intelligent life is aggressive by nature and destroys itself before being able to contact others. Or it destroys others so much that civilisations hide to avoid detection. Alternatively, Earth may be more unique than we assume. Earth has a very specific set-up: an axial tilt of 23° producing seasons, a moon generating tides, a molten core generating a field protecting the atmosphere from being blasted off by radiation, and so on. Life may be impossible without these prerequisites.
Even if life occurs frequently, extinctions may snuff out most civilisations before they develop interstellar communication. There is the idea that other civilisations do exist, but choose not to contact us. Perhaps since we’ve been listening for less than 100 years, we’ve not searched for long enough. Conversely, since humans have only existed for 200,000 years, we may not have existed for long enough to be seen. Scarier options exist, like civilisations reaching a “technological singularity” wherein they are so advanced that we cannot detect their communication. They may no longer be biological, living in a virtual world of their own making so they don’t feel the need to talk to anyone. Stranger still are the Zoo and Planetarium Hypotheses; the former suggests that they don’t contact us to avoid affecting our development and the latter suggests that the real universe is outside our solar system and we are presented with a simulation made to look like there is no other life. It has even been proposed that the Fermi Paradox itself is the reason that we haven’t been contacted, because all other civilisations are adopting a listen-only approach out of fear!
James Ormiston synapsebristol.blogspot.co.uk | 15
ARTICLES
Is Your Immune System Bored? Selective tolerance to bacteria in the gut: how we distinguish between friend and foe
W
e like to think that our body is ours, but the truth is we share it with billions of microorganisms. This collective community within us is referred to as the microbiome, which contains 500 to 1000 different species. To put the size of the microbiome into perspective, for each of our own cells there are 10 more microbial cells present and their collective genome is 100 times the size of ours. Gut bacteria play a key role in many processes, for example metabolizing otherwise indigestible material, converting them into useful substrates for our body functions. The microbiome therefore operates similarly to an externalized organ, underpinning regulatory processes, whilst also creating a highly competitive environment in which pathogenic bacteria struggle to survive. In this sense, we have co-evolved with our microbial tenants, having developed a mutually beneficial, symbiotic relationship. It may seem surprising that we can live in harmony with billions of these micro-organisms on a daily basis, yet just one pathogenic bacterium entering our body can be enough to elicit an immune response. This phenomenon can be attributed to the critical role played by commensal bacteria in our body. As a result of this, we have evolved immunological tolerance mechanisms to maintain our symbiotic relationship with the microbiome. It is this incredible
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process of selective tolerance that will be further explored in this article. How our immune system actually achieves selective tolerance is a topic that has been puzzling immunologists since we discovered the existence of commensal bacteria. However, two very recent breakthroughs have shed light on this process. Dr. Leszek Ignatowicz (George Regents University, GA) discovered that each of us contain a population of tolerogenic lymphocytes called Treg cells. In turn, these Treg cells contain receptors that bind specifically to distinct gut bacterial populations. As a result of this binding the Treg cells become activated, secreting large amounts of immuno-modulatory cytokines such as IL-10, IL-35, and TGFbeta, which dampen the immune response and cause effector T cells to differentiate into more Treg cells. Thus, our Treg cell repertoire changes to reflect our commensal bacteria population. A more recent study carried out by Dr. Gregory F. Sonnenberg (University of Pennsylvania) showed the presence of a new innate lymphoid cell population, called RORgammat cells, lining the surface of the intestines. These cells act as antigen presenting cells, engulfing and presenting commensal bacteria antigens to CD4+ T lymphocytes. However, the result of this presentation is selective suppression rather than activation.
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Our immune system has spent millions of years perfecting this balance of tolerance
This was demonstrated experimentally by knocking out RORgammat antigen presentation in mice, which lead to spontaneous gut inflammation. As one can imagine, strong antibiotic treatments can dramatically change the gut flora population and therefore alter your population of commensal specific Tregs and RORgammat cells. There is a potential risk that this could alter your ability to tolerate commensal bacteria in the future, leading to gut autoimmune diseases such as Krohns and inflammatory bowel disease. On the other hand, too much tolerance to gut bacteria has been suggested to play a role in many chronic inflammatory bowel diseases. Similarly to other mechanisms in our bodies, it is key to maintain homeostasis between opposing processes. Our immune system has spent millions of years perfecting this balance of tolerance,
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and with increasing amounts research into the area there is no reason why we could one day not therapeutically utilize immune tolerance. If harnessed properly, being able to induce cell specific tolerance would have wide applications to autoimmune diseases, such as in cancer treatment where a key goal is the inhibition of tolerance to cancerous cells. Therefore studying our own tolerogenic mechanisms, such as our relationship with commensal bacteria, is extremely relevant to current scientific research and has potential useful applications to the medical issues we are currently facing.
Lily Clayton synapsebristol.blogspot.co.uk | 17
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The Mystery of
Ball Lightning
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uring some thunderstorms, a spherical glow appears, floating in the air for just a few seconds before vanishing. Guesses regarding the origin of these unpredictable glowing orbs have been numerous and range from Peer and Kendl’s (2010) theory of hallucinations being induced by fluctuating magnetic fields created by nearby lightning bolts, to Hughes’ (2011) theory of space debris falling into the atmosphere and ionising it. For centuries, the mysterious phenomenon of ball lightning has lacked a widely accepted scientific explanation. However, recently, a new theory has been proposed. The new theory being considered by scientists is that ball lightning arises when lightning striking the ground vaporises soil silicate minerals. The silicates are stripped of oxygen resulting in energetic silicon atoms being released as a gas. These silicon atoms recombine to form nanoparticles, which float in the air and react with oxygen to release heat and emit a glow. Should this theory be accurate an emission spectrum of the phenomenon
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would show emission lines of silicon and other prevalent elements in the soil, including iron, calcium and aluminium. In fact, in 2012, Ping Yuan and other researchers from the Northwest Normal University in Lanzhou, China recorded video footage of ball lightning which enabled them to obtain an emission spectrum. What they found were emission lines from silicon, iron and calcium as predicted by this new theory. Although it would be convenient to assume that the theory accurately predicts the origin of ball lightning, some discrepancies still remain. For instance, aluminium was expected to be seen in the emission spectra, but no corresponding lines were found. Moreover, it is not clear that this is the only type of ball lightning in existence. Therefore, the theory, if confirmed, may predict the behaviour of this particular type, but could be insufficient in making predictions regarding other types of ball lightning. For now, it seems that ball lightning remains a mystery.
Marta Plaszczyk
Wild Mouse Lemur
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ound only on the island of Madagascar, the smallest and one of the most primitive primates has been hiding a secret; mouse lemurs live twice as long as was originally thought. Weighing just 30-80 grams, captive mouse lemurs tend to live up to six times longer than other mammals of similar size, such as shrews or mice. However, captive grey mouse lemurs (Microcebus murinus) do start to exhibit signs of old age from the age of four including: neurological and behavioural degradation, slowing of motor skills, reduced memory capacity and reduced sense of smell as well as starting to develop grey hairs and cataracts. In the study led in Madagascar, research was carried out on wild brown mouse lemurs (Microcebus rufus). Results revealed that these wild mouse lemurs live to eight years or more, but (unlike the four-year-old captive grey mouse lemurs) they didn’t exhibit signs of senescence. This investigation into why the wild brown mouse lemurs lived longer, led by biologist Sarah Zohdy from the Emory University’s Department of Environmental Sciences and the Rollins School of Public Health, involved capturing the wild mouse lemurs and determining their age using dental moulds. Not only was their age determined, but the mouse lemurs’ faecal samples underwent hormone analysis, revealing some astonishing results. Both male and female mouse lemurs have equal longevity, unlike most vertebrates where the males tend to die first. This is explained by the equal levels
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The Secret of the
of testosterone seen in both genders, most likely due to the fact that mouse lemurs are female dominant. However this does not explain why the wild mouse lemurs do not show signs of ageing at a younger age. Thoughts as to why the wild brown mouse lemurs start to exhibit signs of deterioration at an older age than the captive grey mouse lemurs are due to natural processes that occur in the wild. These include predation, starvation, disease and other environmental stresses that keep the wild brown mouse lemurs alert for as long as possible and those that do show signs of senescence early will fall prey to predators or disease. Furthermore, evidence has shown that some captive conditions may affect mental and physical function, causing the onset of senescence to occur at a much earlier age.
Sophie Groenhof synapsebristol.blogspot.co.uk | 19
ARTICLE
VENOM The Latest Cure for Cancer and HIV?
V
enom is one of the most toxic and lethal substances in the world. So how can it be that venom has in fact saved millions of lives? Scientists have discovered that the potent properties of venom can be used to treat a wide variety of life debilitating diseases from diabetes to potentially cancer and even HIV! So what exactly is venom? There are 100,000 venomous animals around the world. These range from many species of snake, lizards, insects and sea creatures. Venom is composed of a toxic mixture of proteins, which have many different targets and effects. There are two types of venom – neurotoxins and haemotoxins. Neurotoxins attack the central nervous system by blocking signals between nerve cells and muscles, causing paralysis. Haemotoxins work by preventing blood from clotting causing the victim to bleed to death. Venom has evolved to become highly specific and targets the same physiological and molecular pathways as many human diseases. So how can venom specifically be used as a cure? The toxic proteins that make up venom are expressed by genes, therefore by copying
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and manipulating these genes, scientists can refine or recombine the toxin molecules to try and develop new effective drugs. Venom has proven to be an invaluable medical source and many venom-based drugs have been developed to treat a variety of diseases. In fact one of the most common problems in the country, high blood pressure, is treated by a drug derived from the venom of the Brazilian pit viper. This drug was first developed in the 1970s after researchers began questioning why Brazilian plantation workers collapsed after being bitten by the pit viper. The cause was a dramatic fall in blood pressure. After analysing the venom of this snake, researchers found that the drop in blood pressure was caused by a protein in the venom that blocked the action of angiotensin-converting enzyme (ACE) which plays a key role in the molecular pathway that ensures that blood pressure is maintained at the correct level. This led to the development of a synthetic version of the protein which eventually became one of the first ACE inhibitor drugs to treat those with hypertension.
Scientists even believe that venom could be the key that unlocks a medical revolution in the treatment of some of the world’s most life debilitating diseases such as cancer and HIV/AIDS. Research has shown that the neurotoxic venom of the deathstalker scorpion could be used in the treatment of brain cancer. Ultimately the venom contains protein called chlorotoxin which can attach to the surface of cancerous cells. This means that chlorotoxin can be used as a marker, allowing researchers to identify cancerous cells. Currently cancer treatments are quite unreliable, sometimes the tumour is not completely removed and more often than not perfectly healthy cells are destroyed instead of cancerous cells. By using this new marker method, potentially scientists could removed 100% of the tumour and leave healthy cells in tact. Another exciting area of research explores the possibility of using nanoparticles and the venom of bees to treat HIV! The key component of bee venom is a toxic
protein called melittin. The role of nanoparticles is to transport proteins around the body, which is how melittin would be distributed. So how does melittin attack the HIV virus? The toxin is able to effectively pierce a hole into the protective coat of the HIV virus. By targeting the structure of the virus it effectively destroys the virus, stopping it from spreading. However this latest research has only been tested in the lab, therefore it will take years before this treatment is tested in people. Overall we can see that ironically venom, a natural killer, has inspired the development of many life saving treatments and could potentially save even more lives in the future.
Kate Porter Deathstalker Scorpion
synapsebristol.blogspot.co.uk | 21
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James Ormiston
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Did you know? Recently the Hubble Space Telescope took its largest ever photo: a view of about one quarter of the Andromeda Galaxy. The photo is 4.3 gigabytes big, or 4.3 billion (4,300,000,000) bytes. Andromeda contains about 1 trillion (1,000,000,000,000) stars, which means that this image contains over 1,000 times more stars than bytes! J. DALCANTON, B.F. WILLIAMS, L.C JOHNSON, R. GENDLER / UW / PHAT / NASA / ESA
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