What are Chemists Doing to Fight Ebola?

By David Morris  

Since the beginning of 2014, Western Africa has been battling an outbreak of Ebola Haemorrhagic fever (EHF), or simply ‘Ebola’. The epidemic caused by the Ebola virus has been largely contained, but the death toll is still ascending into the tens of thousands. To understand what chemists have been doing to exterminate the virus, some background knowledge of it is required.

An electron micrograph of an Ebola virus 

The Ebola virus is a filamentous virus comprised of a strand of genetic code known as RNA, encapsulated by a protein membrane. It can survive in a multitude of bodily fluids for up to several months, making inter-host transmission very feasible. The fruit bat, native to parts of western Africa serves as a ‘natural reservoir’ for the virus. This means the virus can survive and replicate within a fruit bat without killing it, allowing it to thrive in countries where fruit bats are prevalent. RNA acts as a code for the expression of specific proteins. After the Ebola virus is introduced to the human body, it expresses a protein that binds to human ‘interferons’. These are proteins that call for an immune response when necessary. This binding stops the interferons calling for antibodies to destroy the virus, rendering the immune system largely redundant.

             

The exterior membrane of the virus presents pendant proteins called glycoproteins to the surface of a healthy cell. The Ebola glycoprotein hijacks the cholesterol influx receptors of healthy cells, dragging the virus into them. This allows the virus easy access to the cell interior, where it is free to replicate.

                  

The Ebola virus also expresses a disordered protein called VP24 that interacts strongly with the collagen in the body. Collagen is responsible for separating connective tissues and acting as a barrier to prevent unwanted materials entering organs and tissues. When VP24 interacts with collagen, it can distort the collagen until the collagen is denatured and useless. After this, there is little else stopping blood pouring into organs and to the surface of the skin, thus widespread internal and external bleeding occurs and causes fatal problems in the body.

                   

The many ways that the Ebola virus acts on the body has given chemists just as many platforms from which it can be stopped. Upon entering the body, the virus is very quick to shut down the immune system. The body tries to respond by expressing a specific antibody to combat the virus. Scientists have noticed this and developed an effective way to detect the rapid expression of this antibody, making early diagnosis and recovery from the disease much more likely.

Many contemporary EHF treatments are derived from molecules that are very structurally similar to what the virus uses in protein expression and replication. Sarepta Therapeutics have developed a modified strand of RNA that, when deployed, the virus encounters in the body and mistakes for its own genetic code during replication. Due to the modified code, the daughter virus then goes on to express dysfunctional VP24 which can’t bind to interferons properly, allowing them to signal the immune response to destroy the virus. Similarly, Tekmira Pharmaceuticals have developed ‘small interfering’ RNA drugs that the virus again mistakes for its own RNA. This modified RNA prevents the daughter virus from being able to replicate itself at all. Mapp Biopharmaceuticals developed ZMapp as a ‘cocktail’ of several antibodies that have a high affinity to Ebola glycoprotein. The cell doesn’t mistake the new glycoprotein-ZMapp structure for cholesterol upon binding and so isn’t tricked into allowing the virus into the cell. As the virus cannot infect new cells, it eventually perishes. These techniques have resulted in a plethora of antiviral drugs that can be used to treat EHF. Applying these remedies in conjunction with one another increases the likelihood of effective treatment exponentially as it stops the virus at several points.

                  

These types of drugs work well as they are very structurally similar to the actual virus, such that they have a much higher affinity for the virus as opposed to human cells. This allows the drug to selectively interrupt the virus’ processes over bodily processes, and therefore limits the potential negative effects of the drug on the patient.

                 

Chemists are currently developing methods for EHF drugs to be made in a quick, scalable and economically viable fashion with few toxic impurities, so they can pass through clinical trials and be used on scale. Ebola recovery is now becoming more and more common. With the research effort the pharmaceutical industry is pouring into fighting the Ebola virus, it is very realistic that the epidemic will be exterminated and effectively controlled within the coming years.

The implications of finding a Dyson sphere

By George Thomas

Many people will have recently heard of the potential discovery of an artefact of alien intelligence around the star KIC 8462852 (If you haven’t, read here for more info http://www.iflscience.com/have-we-really-discovered-huge-alien-megastructure-around-star). Further recent study of the star has ruled this out as an option, but it was an interesting idea. With that said, I want to talk about the potential implications of intelligent, highly advanced, alien life existing in our Galaxy.

 

The object that had been speculated as a potential sign of an advanced civilisation is called a ‘Dyson sphere’. Put simply, the idea is that you surround a star in a dome of solar panels to absorb the light energy emitted, to provide enough fuel to sustain your highly advanced alien race. However, surrounding the entire star in a dome isn’t very practical, for multiple reasons, but lots of spaced out satellites could work as a good alternative source for harnessing power. This concept is known as a ‘Dyson bubble’. The presence of a structure like this around KIC 8462852 would have explained the initial observations, but other explanations such as lots of comets are far more likely.

Illustration of a Dyson Bubble
Credit: Wikipedia

 A lot of news outlets had spoken about us potentially finding alien life, but what if there were aliens; would they have found us? Of course, we haven’t got a giant structure surrounding the Sun to give ourselves away, but one way we have been giving ourselves away is in how, at least for the last 100 years, we’ve been broadcasting radio waves across the Galaxy. Unfortunately the radio waves will have become so spread out in their travel that our signal will be indistinguishable from background noise beyond a few lightyears away. Also, in the case of KIC 8462852, the star is too far away (about 1500 lightyears) for our radio waves to have travelled to any potential life stationed there. Unless the species had spread out to stars much closer to our Sun, they wouldn’t have had time to pick up any signs of technology that we may be giving off.

 

There is, however, the Earth itself, which has been harbouring life for the last few billion years. Any intelligent beings looking out at the Galaxy with the technology to detect our pale blue dot will have been able to tell that we’re sitting very comfortably in the habitable zone around the Sun. This is especially true of any species capable of building a Dyson bubble, which begs the question: if there is an advanced civilisation relatively nearby, why haven’t they come to us?

 

The answer, much to the dismay of sci-fi fans, is probably the restrictions of travel through space. Although there are various theories about using wormholes to avoid technically travelling from one point to another at speeds faster than light, the entirety of physics thus far points to a constant restriction: information cannot travel faster than the speed of light.

 

This isn’t definitely the reason, though. An optimistic view could be that life is so overly abundant in the universe that no alien species has bothered to come to us yet. But, as said, this is very optimistic, and the inability to travel to our stellar neighbours in a time considered reasonable compared to the human life span is a far more likely reason. If they have found us, and can reach us, then they’re making an active choice not to engage with us, which would be a curious decision in itself.

This means that although we may in future discover advanced civilisations dotted around our 

galaxy, we may never be able to reach them. We may not be alone in the Universe, but we 

may well be too far away to ever see our neighbours.

The Science of Taste

By David Morris

Structure of a taste bud

In 350 BC, the Greek philosopher Aristotle postulated that varying blends of two tastes, sweetness and bitterness, comprised all flavours. As the understanding of taste developed, it was shown that sourness and saltiness were also distinct tastes. In 1908 the Japanese chemist, Kikunae Ikeda, discovered a fifth subtle and now well established taste known as umami. Until recently, these tastes were universally accepted as the five fundamental detectable tastes that made up all flavours that can be experienced by humans.

The role of smell (olfaction) in flavour wasn’t fully appreciated until as late as 2004, when biologists Richard Axel and Linda Buck discovered the role of the nose in detecting and characterising odours. When you breathe in through your nose, millions of odorous molecules activate and inhibit olfactory receptors at the roof of the nasal cavity. Electrical impulses travel from these receptors to the brain, informing you of what you’re eating. This action is supported by taste buds in the mouth.

Molecules within certain foods can chemically activate senses that are responsible for the sensation of heat, pain or touch. This is known as chemesthesis. Despite being different from taste, chemesthesis can contribute to the flavour of a substance. Examples include the ‘tingle’ on the tongue from ingestion of carbonated drinks, the feeling of heat upon eating a chili pepper, and the cooling feeling from eating gum.

 Taste receptors are mounted on papillae, which are structures found on the front and back of the tongue, the roof and sides of the mouth, and even at the back of the mouth and throat. The idea of a ‘tongue map’ whereby certain areas of the tongue detect certain tastes is a myth, although the concentration of certain receptors may vary in different areas of the tongue.

           Saltiness and sourness are the simplest of the tastes. Sourness arises from the donation of hydrogen ions, which is a characteristic feature of acids. It has been postulated that detection of sour foods defends the body from ailments like indigestion. Similarly, saltiness arises from the dissociation of salt on the tongue, forming sodium and potassium ions. The taste response acts as a warning for your body to replenish electrolytes, but not too much, hence why we find salty foods appealing, but also repulsive in large amounts.

                  

           Bitterness, umami and sweetness are more complicated tastes. They all come from the binding of larger, more complex molecules to large proteins in the taste buds that are typically responsible for signal transduction throughout the body. Bitterness receptors can bind with molecules that are usually toxins or poisons. In this way, the bitter taste warns your body against ingesting molecules that can harm your body.

           Similarly, umami receptors detect glutamate (a component of monosodium glutamate, or MSG, a popular salt substitute), giving off a subtle savoury taste. The subtlety arises because the glutamate is usually bound to sodium, giving off a more powerful salty taste. Glutamate is useful to your body as a neurotransmitter and a catalyst to metabolism, so like salt, the taste warns your body to replenish glutamate, but not excessively.

Tomatoes are rich in umami

           In July of this year, academics at the University of Purdue published a paper in Chemical Senses describing the existence of a sixth taste called oleogustus. Usually, when the body ingests oil or fat, it is in the form of triglyceride, a molecule comprised of three fatty acids chemically bound through a glycerol molecule. This triglyceride is too large to fit into oleogustus receptors and thus can’t be tasted. However, when the fat spoils, the triglyceride is broken down into glycerol and the fatty acids. The fatty acid then binds to the oleogustus receptors and acts as a warning that the food is no longer suitable for ingestion, hence it smells and tastes rancid.

                  

           Each of the aforementioned tastes, as well as the olfactory and chemesthetic systems, have proven essential for the body to be able to consume the correct amount of different types of food, and to protect from ingesting harmful toxins and poisons.

At-Bristol's New Planetarium!

By Laura Rogers

                                                                  

At-Bristol has recently undergone a million pound re-vamp of its planetarium, and I was lucky enough to attend one of their 3D shows.

As the show began, we were told about the extent of the upgrade, and were soon launched from the Earth, with our first view being of the Earth from space. Considering the fact that I get travel sick, so would prefer not to be launched into actual space, this was the closest I will ever be to seeing the earth from above our atmosphere. It was a breath-taking moment, as the three dimensional effects of the planetarium made it feel so real. You could hear the “ahhhh” of the audience as we all stared in amazement.

We then began virtually exploring the solar system, learning about each planet in turn; from being educated about Jupiter’s moons, to the atmosphere of Venus. I had not realised quite how toxic Venus’ atmosphere was, and if we were to actually have landed on the surface, rather than virtually doing so, we would be dead within seconds! However, what was most impressive was that all the comparisons shown were to scale and any incredible figures used were well backed up.

The show not only provided entertainment and spectacular views, but was an educational experience, and is something that I would highly recommend to anyone.