Sunday, 27 January 2013

Synapse science news #12

Dung beetle's guide to the galaxy - Could dung beetles really be guided by the galaxy.  More here.

Can Stress chemically silence genes which are passed on to offspring? - Scientists have recently found evidence to suggest this is true. Read here for more.

First world problems? Will scientists solve the problem of chocolate melting on your biscuits? More information here.

"Fascinating" - The Star Trek Tracker Beam has been invented in miniature. Read more here.

Thursday, 24 January 2013

Polymer Carpets

Hannah Bruce Macdonald

It seems as though every new development nowadays is on the nano-scale, and this is no exception. Professors from the University of Munich and the University of Dresden have improved a method for the synthesis of polymer carpets.

A Polymer Carpet
Polymer carpets are made by grafting styrene polymers onto copper supported graphene and these scientists have discovered that the carpet density and thickness depends on the hydrogenation of the graphene. Graphene is an incredible material, due to its versatility, but what makes it so useful as a support for making polymer carpets is how stable it is to mechanical and chemical influences. The team working on these carpets say that the ‘Polymer carpets exhibit remarkable and unprecedented properties combining extreme thinness, mechanical and chemical stability, robustness, flexibility, and (chemical) sensitivity’. The chemical sensitivity mentioned by the team may sound like a flaw, but this actually means that the nature of the carpet (effectively its thickness, fluffiness or tangled-ness) can be fine-tuned with changes in conditions like the solvent quality, wetting and pH.

Natural (left) and artificial (right) nacre
Polymer carpets are one of those materials that seem to be good at everything. They are similar to biological membranes, such as the outside layer of cells, but have the significant advantage of stability and the ability to withstand considerable pressure. This feature means they have been applied to use in water purification and desalination. Any developments in these fields are of huge importance globally and more research and discoveries in this field could make these polymer carpets a viable solution to the cleanliness of drinking water.

Another unsuspected use of these is in the synthesis of artificial nacre. If, like me, you don’t know what nacre is, it is mother of pearl, the shiny inside coating of some seashells and the outer surface of pearls. Pearls have had many uses over the years, but these tend to be mostly decorative, in jewellery or furniture, but are beginning to be applied in more areas. The pearl is originally made as a surface to protect the molluscs’ soft material from damage through bombardment and protection from parasites. Nacre is now being used as a novel material in medical surgery, as it has been shown to stimulate the growth of cartilage when injected into bones. The ability to make a Nacre alternative in the labs could prove to be advantageous, over having to source it from the sea.

Any improvements in the understanding of the mechanism or the synthesis of polymer carpets is useful, and allows a large step to be taken towards applications such as these, however the greatest use of these diverse materials could yet to be discovered.

Monday, 21 January 2013

Best title ever?

Surely this is the best title on an academic paper you have seen in a long time! The article, published in PLOS Neglected Tropical Diseases, investigates the prevalence of parasitic worms in stool samples. This paper has serious implications for people living in tropical regions and it is written in good humour, check it out here. It also features some stunning figures that must have taken hours to produce.......

Figure 1 from Krauth et al.

Wednesday, 16 January 2013

Weird and Wonderful: The Hooker's Lips plant

Meet Psychotria elata, also known as the ‘hooker’s lips’, ‘hot Lips’ and even ‘Mick Jagger’s lips’ plant. This is not fake, it is a genine plant that can be found in the understory of tropical forests in places such as Costa Rica and Colombia. The vibrant colourful red flowers attract pollinators, including hummingbirds and butterflies. P. Elata acts as a host plant for the golden silkmoth (Xlophanes adalia).

Saturday, 12 January 2013

Relics amongst us

Tom Stubbs

Meet the organisms that have outlived the Egyptian pyramids, the Roman Empire and all humanity.

As humans we are familiar with lifespans on a decadal timescale. Human life expectancies vary globally from 32 to 83 years and the oldest person ever officially recorded was a whopping 122 years old. It is amazing to think animals such as the giant tortoise can live past the age of one hundred, such as the legendary Lonesome George. Nevertheless, these lifespans are truly eclipsed by representatives from the plant kingdom.

The oldest individual living organism on Earth is a bristlecone pine, aptly named Methuselah, from the Hebrew Bible. This individual, hidden away in the ‘Forest of Ancients’ in the Inyo National Forest of California, is an incredible 4,800 years old. To put that into perspective, the tree must have sprouted around 2800 BC! It was already a centenarian before the first Egyptian pyramids and the Mayan civilization would not appear for 800 years. It has existed through wars and the rise and falls of civilisations, yet it still sits there humbly in the mountains of California. Bristlecone Pines are not particularly large, reaching around 50 feet, and they grow very slowly, taking around 700 years to grow 3 feet! At first glance the plant appears rather drab, but so would you if you had outlasted every other single organism on the planet.

Believe it or not, Methuselah is not the oldest recorded individual tree, there is a member of the same species that was older. This was Prometheus, which might have been 5,000 years old. Unfortunately Prometheus was felled by an enthusiastic graduate student in 1964! There is a chance that Methuselah may over take its rival and continue to live past our great-great grandchildren. Who knows, scientists might be blogging about a 6,000 years old tree in the very distant future.

Bristlecone pines are not the only primeval trees living amongst us. There is the giant 82 feet high cypress named Zoroastrian Sarv (or Sarv-e-Abarkooh). This individual evergreen is between 4,000 and 4,500 years old, around the same as Stonehenge! It can be found in Abarkooh, Iran.

So why do some trees live so long? Their compartmentalised vascular system helps considerably, allowing sections of the tree to deteriorate while the individual survives. They also have the ability to synthesise defensive compounds to protect against parasites and bacteria. An underlying physiological mechanism prevents genetic mutations from accumulating in their cells to the same extent as other organisms. Longevity is naturally selected as it increases the organism’s reproductive opportunities.

We have trees that have existed for thousands of years, how would you feel if I told you there are plants that may have lived for tens and hundreds of thousands of years, surely not? The exceptional trees described above are all individual units, with a single stem and root system. There are a group of plants which have evolved a clonal mode of life. This involves using many genetically identical clones stems that to the untrained eye, appear to be individual trees, but beneath the surface they are all connected in a massive network of roots. This allows these plants to defy time. The loss of a single unit stem or ‘tree’ does not mean the death of the overall organism and clonal colonies can live for incredibly long periods.

Part of the 'Pando' colony
Perhaps the most famous ancient clonal colony is ‘Pando’, a colony of Quaking Aspen in Utah. This colony is 80,000 years old, so compared to this Methuselah looks like a spring chicken! An age of 80,000 years is difficult to comprehend, but during this time our ancestors were all confined to Africa. Unbelievably some reputable estimates believe the colony could be as old as 1 million years. If so Pando would be 800,000 years older than the earliest human. Also known as the ‘The Trembling Giant’ Pando is made up of 47,000 stems that are clones of a single male aspen, when a stem dies it is simply replenished. Together this colossus weighs 6,000,000 kg making Pando the heaviest living organism on earth.

Old Tjikko
If you consider Pando a cheat for being made up of multiple stems then check out Old Tjikko. This ancient spruce tree from Sweden is 9,550 years old, twice the age of Methuselah. Unlike Pando this tree has only a single stem, so it looks like a normal tree. However, this stem is just one of many and is only 600 years old. It is a clone that is continuously replaced from an ancient root stock.

In February 2012 a new contender to the title of oldest colonial organism was announced. To find it we have to venture into the marine realm. Reports suggested a species of seagrass, Posidonia oceanica, along the Mediterranean coast is between 80,000 and 200,000 years old. It looks like a meadow but as with other clonal colonies, it is all one genetic individual. Ironically, this ancient seagrass now faces its greatest threat - humanity. Induced Mediterranean climate change is causing P. oceanica meadows to decline by around 5% each year. You will also remember that it was a freak human related accident that led to the felling of Prometheus and ‘The Senator’, previously the fifth oldest living tree, was burnt down by a woman in Florida in 2012! As a species we must be careful we do not destroy these wonderful relics.

Wednesday, 9 January 2013

Feeling sleepy? The science of anaesthesia

Jonathan Smith

The discovery of the first inhalational anaesthetics in 1846 changed how surgery was carried out. Instead of needing to complete a procedure in the fastest time possible amidst the protests of a fully aware patient, a surgeon was able to attempt much more ambitious techniques while the patient was held in a painless state of unconsciousness. Today, anaesthetic drugs can be administered intravenously (e.g. Thiopental) or by inhalation (e.g. Isoflurane). There are many levels of anaesthesia ranging from full consciousness through sedation down to the loss of consciousness, loss of reflexes and analgesia. Additionally, cardiac and respiratory muscle contraction are weakened at surgical doses and for this reason, there is often a narrow margin between surgical anaesthesia and respiratory death. Anaesthetists have the fiddly task of monitoring and adjusting the level of anaesthesia throughout surgery.

Anaesthesia of a patient occurs in three main phases: induction, maintenance and recovery. A common procedure in major surgery is to induce unconsciousness rapidly with an intravenous agent, maintain unconsciousness using inhalational anaesthetics and withdraw them in the recovery stage. Additional application of painkilling drugs such as opioids and neuromuscular blockers (relaxants) is often made. The speed of recovery needs to be maximised so that the chance of respiratory failure is kept low.

How do these drugs actually work? Inhalational and intravenous agents are all soluble in lipids to varying degrees and this is an important factor determining their characteristics. This solubility means that they easily cross lipid-based cell membranes and alter cellular function. It is thought that anaesthetics accumulate in cell membranes and influence the excitability of the cells. This can be through the increase of inhibitory transmission or the decrease of excitatory transmission or both. By doing this, anaesthetics are able to depress the nervous system and induce a loss of function.

This lipid solubility also affects other aspects of anaesthesia. Inhalational anaesthetics must cross from the lungs into the bloodstream and often take longer to exert their effect than injected anaesthetics. In addition to higher potency, high lipid solubility in these agents means that the onset and recovery from anaesthesia is slower. If a patient has higher amounts of fatty tissue such as in obesity, the extra fat sponges up large amounts of the drug and as a result, obese patients are much harder to anaesthetise.

Though anaesthesia always carries risks, these are often short-term. One long-term risk that has been hypothesised is the effect of anaesthetics on child development. Epidemiological studies and preclinical studies on rodents have suggested that the depressant effect of anaesthesia may have a permanent impact in the maturation of infant nervous systems that are very sensitive to environmental factors. In reality, however, this risk is not proven since the anaesthesia in these studies is difficult to separate from diseases that the child had at the time and translation of rodent studies to human is also difficult e.g. differences in development rates.

In summary, general anaesthetics are an essential part of surgery due to inducing a loss of consciousness that makes procedures much easier for all parties. Their non-specific mechanism of action also means that there are many risks, especially in the respiratory system.

Thursday, 3 January 2013

The Return of SARS?

Sophia Ho

The presence of a new coronavirus was confirmed by the World Health Organisation (WHO) on September 22nd 2012, following tests on a hospitalized 49 year old Qatari man who first presented symptoms of acute respiratory infection on September 3rd. After being admitted into intensive care in Doha, Qatar a few days later, he was then moved to a hospital in London by air-ambulance on September 11th. The novel virus contracted by the man was found in only one other case, that of a 60-year old Saudi Arabian. In addition, it has been reported in late September that five other individuals in Denmark have been placed in isolation as a result of carrying symptoms of the same viral illness and are to be tested. They included an individual who had travelled to Qatar and four members of a family whose father had recently gone to Saudi Arabia. At the time of writing, 3 of the 5 cases from Saudi Arabia and both cases from Qatar have resulted in fatality. 
Coronaviruses are a group of viruses that have a halo, or
 crown-like (corona) appearance when viewed under an
electron microscope

What makes these cases appear alarming is the understanding that the coronaviruses are a genus of viruses that includes the SARS coronavirus, or SARS-CoV, which causes the well-known and potentially fatal Severe Acute Respiratory Syndrome. SARS is characterized by symptoms of fever, muscle pain and headache, followed by coughing, dyspnea (shortness of breath) and pneumonia. It can also lead to a decrease in circulating lymphocytes (a type of white blood cell). During the outbreak in 2003, which originated in Guangdong province in Southern China, over 8000 cases were reported worldwide in addition to approximately 800 deaths, leading to a mortality rate of around 10%. However, this was considerably higher for victims over 50 years of age, reaching up to 50%.

SARS-CoV itself is an enveloped, single-stranded RNA virus (as opposed to double-stranded DNA, as found in most other living organisms) with a genome size of 29.7kb, among the largest within RNA viruses. Its life cycle begins with host cell entry, requiring the uncoating of the virus particle and insertion of its RNA genome into the host cell cytoplasm. Once internalized, all viruses utilize their host’s cellular machinery (proteins, cytoskeleton etc) for their own replication requirements. Different coronavirus infections can have various effects on the host cell’s transcription and translation processes, resulting in effects on the cell cycle, cell survival/death, the cytoskeleton and, on a bigger scale, inflammation and immune or stress responses.

Schematic representation of a coronavirus
Other coronaviruses are known to be among the major causes of the common cold, and some are able to infect the gastrointestinal tract. The virus is spread via droplets produced during coughs and sneezes. The illnesses observed in the recent cases described above show similarities to SARS, in that they also produce severe respiratory conditions and have the potential to cause fatality. The WHO therefore proceeded to “further characterize the novel coronavirus", and the UK’s Health Protection Agency are also working to sequence the virus using samples derived from the Qatari case.

Since then, virologists in Holland have been able to sequence the entire genome of the new virus (temporarily named ‘Novel coronavirus 2012’, ‘London1_novel CoV 2012’, and ‘Saudi SARS’) and have claimed that it appears more closely related to coronaviruses that infect bats than human SARS-CoV. Bats are a natural carrier of many types of coronaviruses, making them a likely reservoir. It is also probable that, rather than contracting the virus directly from bats, transference to humans may have occurred via an additional host(s), such as the civet cat. Indeed, very recently released research findings suggest that the novel virus uses host receptor molecules that are present in primates, pigs and bats, leading to the possibility of cross-species spread. Alternatively, it has been speculated that it may be a mutation of a previously existing virus.

Despite this new data, information about the novel coronavirus is still considered too limited to draw solid conclusions. It is not yet clear whether the pathogenesis exhibited by the small numbers of cases so far represent the normal effects of the new virus on humans, or merely very rare incidences of severe disease caused by the virus. Health officials and virology experts have not so far raised much alarm concerning safety of the public for a number of reasons.

1. The number of cases where the new virus has been detected have so far been very few. In addition, none of the 60 people who recently came into contact with one of the victims were shown to have any indication of being infected with the virus, after being tracked. It is therefore not believed to be as contagious as SARS.

2. No increase in the numbers of new cases of respiratory illness has been observed in countries where the patients originated from. This strongly suggests that, as of now, the virus may not be able to spread between humans but instead acquired from an animal source.

3. Coronaviruses are easily destroyed using normal cleaning agents and detergents and are only able to live for one day outside of the human body, making them easy to manage.

As a result, the WHO have not yet proposed any travel or trade restrictions, but plans have been made to continue closely monitoring the situation and to review new findings. Dutch virologist Dr. Ron Fouchier and his group, who were responsible for sequencing the novel coronavirus genome, have issued a diagnostic test for the virus, enabling suspected cases to be verified worldwide, and are working to find proof that the virus is the main cause of the disease (as opposed to, for example, compromising the immune system and enabling another agent to cause the fatal respiratory illnesses observed), using macaques and ferrets. Fouchier also stated that vaccine design can now begin for the virus, using alterations to existing knowledge based on experimental vaccines for SARS. Due to the nature of viral reproduction, which usually involves a high mutation rate during replication, there is still some chance that the Novel coronavirus 2012 may at some point modify to become a more dangerous, transmissible pathogen. However, given that there is no evidence of human-to-human transmission as of now, there appears to be little need to panic for the time being.