Science Week 2017: fungi in heritage buildings

Dr Clare Sanson, Senior Associate Lecturer in Biological Sciences, writes on Sophie Downes’ talk on fungi and conservation in heritage buildings.mushroom-2198010_1920The Department of Biological Sciences’ contributions to Birkbeck Science Week 2017 focused on ‘Microbes in the Real World’. Apart from that over-arching theme, however, the two sessions could hardly have been more different. The Week kicked off with a lecture by PhD candidate Sophie Downes on the interactions between fungi and heritage buildings. As far as I am aware, Sophie is the first Birkbeck student to have given a Science Week lecture; she spoke with confidence and clarity, and held her audience well.

Nicholas Keep, Executive Dean of the School of Science at Birkbeck, introduced Sophie as a graduate of the University of Lincoln who had worked in textile conservation before moving to Birkbeck to study for a doctorate in Jane Nicklin’s mycology lab. She began her lecture by explaining the context of her research: her job had been based in a large Elizabethan house that had problems with pests and condensation, particularly in the show rooms. The need to find out how best to preserve and repair organic material in buildings like this one led directly to her PhD studies.

In the UK we have a huge number of historic buildings, many of which are popular tourist attractions and play an important role in the local economy, particularly in rural areas. A large number of these are maintained by the National Trust or English Heritage, and many are open to the public for the majority of the year. The thousands of visitors drifting through properties will affect the number and types of micro-organisms, particularly fungi, found there. Sophie’s project included a year-long survey, starting in the autumn of 2013, of fungi found in 20 historic buildings in England, Wales and Northern Ireland. These included cottages and wartime tunnels as well as the more usual castles and mansions, so the survey could be expected to provide a snapshot of fungi and fungal damage in a wide range of historic properties in the UK.

When we think of fungi, we tend to think of so-called ‘macro’ fungi: this category includes the mushrooms we eat and poisonous toadstools, but also dry rot. Micro-fungi are harder to spot, but they are at least as pervasive and colonise an enormous range of organic matter, producing spores. For example, they are responsible for the blue colouration often found on stale bread and preserves. Micro-fungi will colonise almost any organic object that they find in their way, which, in the context of a historic building, might include wood, tapestry, leather book bindings and silk wall hangings. Sophie used air sampling and sterile swabs to obtain representative fungal samples from one outdoor and four indoor locations at each building and recorded the position of and features in each room or area selected, with its temperature and relative humidity.

Sophie landed up with a total of 4,000 samples to analyse, which, given her limited time, was too many for wholescale sequencing. She started by separating these according to colour and morphology and then selected representative samples for DNA extraction and ‘barcode screening’, and fewer for DNA sequencing.  A total of 158 different fungal species from 77 genera were identified, with the most abundant genera being Aspergillus, Cladosporium and Penicillium. Some of the organisms found in smaller quantities, including fungal plant pathogens probably from the outside air and bacteria, were shed from visitors’ skin scales. Both the number of colony forming units and the diversity of fungal species recorded increased during the summer months.

Resident fungi can carry a small risk to human visitors to the buildings and perhaps a slightly higher risk to curators, given their higher exposure times. Fortunately, only a small fraction of the fungi identified were ‘nasty’ human pathogens, and all but one of these were classified in the lowest-risk group, Category 2. A larger number were recognised as of potential risk to particularly vulnerable individuals with damaged immune systems, and more still are only hazardous to the external environment.

The temperature, the height of the building, the type of room and amount of furnishings were found to be the most important factors in determining the extent of fungal growth within buildings and if high colony forming units would be observed, and the three most common fungal species in both the air and the swab samples – Penicillium brevicompactum, Cladosporium cladosporioides and Aspergillus versicolor – have frequently been reported in organic material in historical collections worldwide.

Fungi damage textiles and other organic materials by secreting enzymes that break down polymers, forming secondary metabolic products that cause further degradation. This process has important effects on the physical, chemical and mechanical properties of the materials. Sophie described how she had evaluated each of these, starting with the effect of fungal growth on the physical properties of cotton. Cladosporium infestation is known to cotton fibres, causing an unattractive colour change that cannot be removed by cleaning. She incubated new cotton strips with several fungal species and monitored them for 12 weeks using a technique known as colorimetry. Each fungus caused a gradual colour change, with Cladosporium causing by far the darkest stains. She also reconstructed images of fungi colonising woven cotton fibres in 3D with confocal fluorescence scanning microscopy.

Most fungi have long, filamentous structures called hyphae that secrete enzymes at their tips as they grow. These enzymes break down large and small organic molecules into nutrients; it is the breakdown of large molecules – polymers such as collagen, cellulose, fibroin and keratin – that cause chemical damage to heritage materials. Chitin and keratin are among the most complex organic substrates that fungi can digest and require several enzymes to break them down. Nevertheless, the three commonest species of fungi all managed to reduce the protein content of protein-containing fibres significantly, with Penicillium causing particularly serious damage to collagen. Fungal digestion also changed the local structure of protein fibres. And one net result of this chemical degradation is a change in the mechanical properties of the materials; for example, fungal infestation tends to cause silk to become more brittle.

But what are the implications of these results for the conservation of objects in historic buildings? All the test were conducted on modern materials, and aged ones, which are already worn, are bound to be more vulnerable. Sophie ended a fascinating talk by suggesting that this research will help to inform conservation protocols for the handling, treatment and risk factors involved with fungal contamination of historic collections.

. Reply . Category: Science . Tags: , , , , , , , , ,

Science Week 2017: understanding climate change

This blog was written by Giulia Magnarini, Birkbeck graduate in Planetary Sciences with Astronomy and PhD candidate in Earth Sciences at UCL.scienceweekclimatechange850x450To understand current climate changes, we need to understand past events. However, using our existing climate model is really difficult.’ This is how Professor Andrew Carter began his talk on Earth’s long-term climate. Professor Carter’s research focuses on studying Antarctica in terms of climate changes.

Despite some persistent denial, evidence for an increasingly warm climate is clear. To provide a visual idea of the impact that the total melt of ice in Antarctica could have, Professor Carter asked the audience to imagine Big Ben under water up to the clock. Thames barriers would be ineffective and it is increasingly obvious how important research on climate change to tackle its consequential threats is.

Geological evidence for the first appearance of the ice sheet in Antarctica resides in sediments that date from 33 million years ago. The question is: why did Antarctica freeze over? Two hypotheses are proposed. The first one involved plate tectonics; as Antarctica separated from Australia and South America (circa 50 million years ago), ocean circulation changed and the strong Antarctic Circumpolar Current emerged, causing thermal isolation of the continent.

The second one takes reduction of atmospheric carbon dioxide into account. Historic data collected for ice volume, deep sea temperature and sea level all follow the same trend of the reconstructed amount of carbon dioxide in the atmosphere.

However, there are problems with both hypotheses. For instance, at the moment of the break, Antarctica was in a northern position and, although carbon dioxide was lower, overall temperature was warmer.

There are many difficulties in modelling over geological time. Nowadays, different models running for Antarctica show completely different results. Improving the quality of data is crucial because uncertainties are very high. On this point, Professor Carter has been conducting what is called ‘provenance analysis.’ This involves studying sand grains to locate their sources to better constrain past tectonic events and past environmental conditions. The grains that Professor Carter studies have typical shape due to ice erosion. Detrital zircons (very resistant minerals) are used to conduct U-Pb geochronological assessments to reconstruct the age distribution of the sediments. These ages are then compared with rocks from different areas for which age is known.

Oceanic drilling programs have been conducted within the ‘Iceberg Alley’. This is an area where icebergs are transported by currents and during the journey they deposit sediments. Results from sediment cores have shown that the grains come from other areas, meaning that they had been transported by icebergs, therefore implying that ice was already present on the continent at that time.

This new set of information can help improving tectonic models related to the opening of oceanic passages. Sampling the ‘Shag Rocks’, which are the only exposed part of the continental block within the Iceberg Alley, would be of benefit for this. Unfortunately, due to strong currents, this can be very difficult and dangerous.

Professor Carter concluded by pointing out the importance of better understanding the geology of this area because it was here that the Antarctic Circumpolar Current originated. This in turn had a significant implication on the global cooling of the planet. In fact, its influence reaches up to the northern hemisphere.

Therefore, more geological data can greatly improve the quality of climatic models. Better and more reliable climatic models will be fundamental to help future governments make important decisions.

. Reply . Category: Science . Tags: , , , , ,

Science Week 2017: geoengineering, climate change and evolution

This blog was written by Giulia Magnarini, Birkbeck graduate in Planetary Sciences with Astronomy and PhD candidate in Earth Sciences at UCL.geoengineeringmethods-climatecentral1-2To our knowledge, Earth is the only planet where life has developed. Life appeared very soon after the formation of our planet about 4.5 billion years ago, and continues to survive.

Dr. Philippe Pogge Von Strandmann examined the mechanisms that keep the Earth habitable in a recent talk. He noted that despite large oscillations between cold periods (ice ages) and warmer intervals (interglacial stages), our planet has managed to avoid the fates of Mars and Venus. Both of these planets have lost their oceans, while Earth has retained liquid water at its surface.

Meteorite impacts, glaciations and volcanic eruptions are some of the processes that mark the very dynamic history of the Earth. Atmospheric composition has also changed dramatically over time, formerly being composed of mainly CO2, to the increase of nitrogen and oxygen. These events across Earth’s history have caused extinction of some species, but life has survived nevertheless, and continues to adapt and evolve.

Dr. Von Strandmann illustrated some of the theories that aim to explain the endurance of life on our planet – for instance, Gaia Theory, the Medea Hypothesis, the Daisyworld Experiment – and explored the influence of geological processes on climate mitigation. Carbon dioxide, a greenhouse gas, dictates atmospheric and surface temperature; therefore its atmospheric abundance is critical in long-term climate change. Plate tectonics play an important role by removing gases through subduction (where oceanic plates sink under continental plates) and re-emitting them through eruptions. But this process is slow, acting on a time scale of hundreds of millions of years. The weathering of rocks is a more effective process. Dissolved material is washed away by rivers into oceans to form rocks, which lock crucial amounts of carbon dioxide inside.

Dr. Von Strandmann concluded his talk with considerations about consequences of human actions in the face of the current climatic stage. Atmospheric CO2 has surpassed the barrier of 400 ppm (parts per million) and over the last decade, every year has been hotter than the one prior. This is evidence we can neither deny nor ignore. Climate change is going to exert challenging environmental pressures, for instance in a reduction of land available for agriculture. Geoengineers are committed to finding ways to actively remove carbon dioxide from the atmosphere. However, the effects of carbon sequestration are still unknown and more research is needed.scienceweekgeoengineeringoriginalThe second speaker, PhD candidate Tianchen Hen, illustrated the emergence of animals that occurred as oxygen levels began to rise. About 540 million years ago, the Cambrian fauna started diversifying from the Ediacaran fauna, introducing several biological innovations. This event is known as the ‘Cambrian Explosion’, and is characterised by an accelerated rate of diversification. Cambrian rocks preserve amazing fossil records, dominated by Trilobites – the first representation of animals that we can call our ancestors.

What seems to be a sudden change in the fossil record has caused significant debate. Charles Darwin noted it to be the main counter-argument to his evolutionary theory of natural selection. However, although all Ediacaran fauna became extinct and were replaced by Cambrian fauna, there is not a distinct separation. Both faunae share a certain degree of diversification and show symmetrical structures. Indeed, molecular biology suggests that a co-occurrence is rooted in the Ediacaran fauna.

The rise of oxygen levels is vital for animal metabolism. It influences body size and allows more intense activities. However, it is unlikely that just one mechanism can explain the triggering of early animal radiation. Tianchen Hen explained other possible factors that may have contributed. Hox genes are responsible for biological innovations, such as appearance of limbs and eyes that could induce behavioural changes. These changes may have refined the relationship between predators and prey, bringing diversification in the battle to survive. Warmer temperatures following the period of extensive glaciations, known as the ‘Snowball Earth’, may have also played a part. The consequent rise of sea-levels expanded habitable shallow sea zones. Moreover, the post ‘Snowball’ stage caused an increased availability of minerals and nutrients.

The interaction between abiotic and biotic processes is extremely fascinating and deserves a better understanding – life as we know it depends on it.

. Reply . Category: Science . Tags: , , , , , ,

Crossing the Mediterranean sea by boat: human dignity and biophysical violence

This blog was written by Haley Curran, a PhD candidate in Psychosocial Studies at Birkbeck.

MigrationDr Vicki Squire gave a talk at the Birkbeck Institute for Social Research on 29 March, on how the treatment of people on the move in Europe has provided a new lens through which we can understand why there has been no sustainable and humane policy implementation from European leaders, or more pressure from the wider public to address the current migration crisis.

What is biophysical violence?
Biophysical violence relates to the governing of migration through death and derives from Foucault’s notion of biopower and biopolitical racism ‘to make live and let die’. It is a particular governmental regime that separates people into groups- those that are ‘productive’ and those that are ‘unproductive’ and therefore values some groups over others. Biophysical violence can help to mask certain wider policies and practices.

This takes on a racialised form when looking at the refugee crisis in Europe and challenges the notion of Europe as a safe and welcoming space. It also brings the notion of privilege to light and the stark differences between certain groups of people making a journey across Europe compared to others. It is not the same for everyone and certain groups in society will occupy a much more precarious space when they are on the move.

There has also been an emergence of death as a ‘normalised’ concept for certain groups of people migrating and making the journey across Europe. People have been left to die in the name of security.

Biophysical violence also takes into account the significance of physical elements (deserts, seas, inclement weather conditions) which cause the deaths of countless people attempting their journey to and across Europe.

Culpability can also have a role to play in analysing biophysical violence and can perpetuate the ‘normalisation’ of death for certain groups of people on the move:

    • the evasion of culpability- natural forces as a cause of death at borders and along the routes
    • the displacement culpability- shifting the responsibility on to the person making the journey – it’s their fault as they were unable or unwilling to recognise the perils in making that journey
    • the rejection of culpability- the presence of a third actor, such as the people/ person smuggler as the cause of death.

The role of humanitarian responses:
While Search and Rescue missions may be helping to save lives at sea, what happens to those migrants if they are handed over to the authorities and detention centres?

Messaging around pity, sympathy and victimisation can be counter-productive in countering the fear and suspicion in populist sentiment towards people on the move. Humanitarian messaging is dependent on the innocence of the victim and is based on fleeting emotions. Instead they should be looking to create more sustainable interactions based on a relational model of empathy, mutual respect and dignity (politics of empathy & mutual respect). Politics of pity/sympathy can also be present in compensatory reactions to biophysical violence, such as large displays of grief.

Interventions challenging biophysical violence:
Where there is darkness there is also light and hope. The true spirit of humanity counteracts this grim and harrowing picture of violence and aggression with interventions grounded in empathy, dignity and respect.

‘Corridoi Umanitari’ (Humanitarian Corridors) is an initiative that is run by faith groups in Italy. Their focus is on safe and legal routes through assessing people in Lebanon in ‘vulnerable conditions’ (victims of persecution, torture and violence, as well as families with children, elderly people, sick people and people with disabilities) for legal entry to Italian territory with a humanitarian visa and the possibility to apply for asylum. They are flown to Italy and are helped with integrating, housing and learning the language upon arrival.

City Plaza Squat, a squat based in Athens in a disused hotel, houses refugees and activists together. There is a balance of backgrounds, gender, those who may require some support, and those who can provide it. This community does not define people by their ‘vulnerability’ and is a good example of integration and mutual respect.

Final thoughts:
This talk was lively and interesting, throwing up as many questions as it did solutions. There is no easy answer to this complex and politically charged situation and it is going to take creativity and innovation to implement solutions.

What is clear is that a new politics of empathy and respect needs to emerge to address this crisis in a humane way. Human mobility has always been a part of our history and has shaped Europe today, but the right to mobility is currently very unequal.

Safe and legal routes could be one way to address the chaotic and dangerous journeys and may also help to provide some confidence in European decision makers. It will take courage and bravery to take these steps however and it remains to be seen who will take that first step.

. Reply . Category: Social Sciences History and Philosophy . Tags: , , , , , , , ,