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.

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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.

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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.

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“Boy Brain, Girl Brain” – A TRIGGER Seminar on Cognitive Early Development

This post was contributed by Lucy Tallentire, from the School of Business, Economics and Informatics

boygirlSex differences have been the source of contentious debate in recent years, beguiling scientists, lay people and major stakeholders like the NHS and pharmaceutical companies. There are obvious physiological and anatomical differences between the sexes but cognitive differences are often conveyed through stereotypes – that males have better motor and spatial abilities and females have superior memory and social cognition skills, for example. While there is research to support some areas of cognitive sex difference, recent studies have shown that the magnitude of sex differences has decreased in recent years. This suggests the causes of these differences may have less to do with one’s genetics than one’s environment – that nurture may be just as powerful as nature to one’s brain development. It also provides further evidence for the effectiveness of contemporary social movements to bridge the gap between “women’s roles” as nurturing child-bearers and “men’s roles” as workers.

So what can research into typical and atypical early development tell us about sex differences? And should we be focusing on biology as the route of sex differences?  These were just some of the questions addressed by guest speaker Teodora Gliga, from Birkbeck’s Centre for Brain and Cognitive Development, at a special seminar on Wednesday 7 December. The event was arranged and hosted by the Birkbeck TRIGGER initiative, a European-wide research project dedicated to Transforming Institutions by Gendering Contents and Gaining Equality in Research.

Why look at sex differences?

Hormonal differences initiated by biology and genes affect physical and cognitive development; the genes on sex chromosomes and the levels of sex hormones influence the brain during early development. Many psychiatric disorders are more common either in boys or girls; boys are more likely to develop autism – the focus of Teea’s research – but girls are more prone to anxiety. By utilising animal models of development and human studies that have revealed early biological differences between sexes present even before birth, Teodora was able to explain differences in susceptibility to risk factors associated with autism.

However, that the effect is amplified when the brain is exposed to risk factors or adversity, such as stress, demonstrates that biology is not the only variable in the development of a disorder like autism; recent research by Anne Fausto-Sterling on how best to study difference in infant early development has shown that, although birth characteristics provide a moment to begin analysis of developmental processes that lead to sex-related differences in behaviour and preference, this is an arbitrary starting point. Many of the biologically-oriented studies use prenatal sex differences in hormone production as the explanation for later difference in behaviour but according to Fausto-Sterling, it seems likely that hormones are but one of many factors affecting human foetal growth and development. In this framework, behaviour after birth develops independently as small biological differences are slowly magnified by external influences – social, cultural and environmental.

Case Study: The British Autism Study of Infant Siblings

The British Autism Study of Infant Siblings was established to explore the development of autism in young infants, and to advance and improve early detection and diagnosis. Parents frequently tell medical professionals that they knew there was something different about their child’s development quite early on, often long before an official diagnosis is received. However, it has been hard for researchers and clinicians to know about the very early signs for autism as they typically only see the child when they are over three years old, when a diagnosis can be reliably given. Although diagnoses for autism spectrum disorder (ASD) have fallen in recent years, it remains more commonly developed by boys – 1:42 boys and 1:189 girls, according to studies from 2010 and 2014.

Scientific understanding of the neurobiological basis of autism has advanced dramatically in past decades, but there is still very little known about how the condition develops over the first few years. This is precisely why Teea’s team at the Birkbeck Babylab launched the Studying Autism and ADHD Risks (STAARS) project, which looks specifically at the early development of baby brothers and sisters of children with autism spectrum disorders, attention deficit disorders and typical development. The project is notably an output of the TRIGGER programme, as the initiative provided the funding for the research assistant who carried out the analysis.

Of the participants with elder siblings with an ASD diagnosis, 20% went on to develop and get a diagnosis for ASD. The study showed a negative correlation between IQ and severity of symptoms, which provides further evidence that IQ is a protective factor against the development of autism. But Teodora was quick to remind the audience that there is still a lot of debate on these findings – there has not been one specific gene that can explain more than 10% of cases. One must also consider that the symptoms of autism might be exposed more easily in this case study, as it must be conducted on “High Risk” families, where they might be more actively looking for symptoms because of a heightened awareness of autism, and where interactions with siblings with an ASD diagnosis might even be a contributory environmental factor.

Teea finished her presentation with a call for more statistics and better models through which to analyse these statistics. If we are to gain a deeper understanding of ASD, its causes and its early detection, we must focus first on mediating effects that may reveal protective mechanisms, and on increasing our understanding of underlying biology of sex differences and the implications of hormones. According to the expert, “it is a story of interactions between biological, social and cultural factors with cascading effects.”

Further Links:

The TRIGGER team at Birkbeck is currently seeking mentees and mentors for their Athena SWAN mentoring programme 2016/17. The mentoring scheme is open to research, technical and academic staff who work at Birkbeck – find out more here.

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