Microbe Talk: August 2015

Could the mud and soil a person walks through be used to identify where they’ve been? In part two of our forensic microbiology special, we look at the ways that soil from crime scenes can help pinpoint the whereabouts of people and objects in police investigations.

We spoke to Professor Lorna Dawson from the James Hutton Institute about her work on criminal cases, and how microbiology is being used to enhance the field of soil forensics.

Show notes:

  • Lorna Dawson’s homepage.
  • Part one of our forensic microbiology special can be found here.

Don’t forget, you can subscribe to Microbe Talk on iTunes. You can also find us on Soundcloud and Stitcher.

Anand Jagatia

Image credit: Alan Cleaver on Flickr under CC BY 2.0
Music:
‘Submerging Blue-Black’ by Podington Bear, under CC BY-NC 3.0
‘I Am Running Down the Long Hallway of Viewmont Elementary’ by Chris Zabriskie, under CC BY 4.0
‘Trio for Piano Violin and Viola’ by Kevin MacLeod, under CC BY 3.0
‘Lips’ by Plurabelle under CC BY-NC-SA 3.0
Sound Effects: From freesound.org.
‘Walking1_gravel’ by tec studios, under CC0 1.0
‘CarStartAndDriveOff’ by jmdh, under CC0 1.0
‘BikeBellWhileRiding’ byqubodup, under CC BY 3.0
‘Woodland Birdsong June’ by justkiddink, under CC BY 3.0
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Could our internal clocks be a mechanism for viral resistance?

watch innardsWhat are the underhanded tactics that viruses use during infection? How might the time of day affect the body’s response to a virus? Dr Rachel Edgar, a Research Associate based at the Wellcome Trust-MRC Institute of Metabolic Science at the University of Cambridge, investigates the game of strategy and timing that has played out for hundreds of millions of years, as organisms’ immune systems defend against the unrelenting invasion of pathogens.

Like so many of the systems in our bodies, the immune system is regulated by ‘circadian rhythms’, the inbuilt cellular clocks that are found in many living things, from archaea to zebras. These clocks allow regular changes in biological behaviour, enabling organisms to anticipate and respond to environmental changes, be they beneficial or noxious.

In humans, the most obvious reminder of our circadian clocks is our daily sleep–wake cycle, but their influence is much wider, impacting hormone release, cell regeneration, body temperature and metabolism. The immune system is in its prime state when attacks are most likely and undergoes the necessary repair and regeneration when the body is resting. Research suggests that in mice, for example, the immune system is poised to respond to an oncoming invasion just before early evening. Because circadian rhythms are evolutionarily ancient, there is the real possibility that pathogens will have co-evolved to capitalise on the predictable changes in organisms’ immune systems.

Dr Edgar wants to find out if the time of day at which the body is infected affects either a virus’s ability to replicate in cells or the progression of the disease in animals. “I suspected that this would have already been looked at,” she said, “but as it turns out, with regards to virus infection, nobody has looked to see if there was a timing effect.

“The amazing thing about the clocks is how reliable they are, even without external cues. Say you were locked in a darkened room for a long period of time, you’d still have your circadian rhythms,” Rachel explained. When external cues are present, the internal clock tunes itself to make sure it is in time with regular changes in the environment, such as light–dark cycles.

Some of Rachel’s experiments involve infecting a cell or whole animal with special viruses that express luciferase, an enzyme that causes light to be emitted. The amount of light emitted can be measured, allowing her to monitor how quickly the virus is replicating or how the disease is progressing. She uses two different approaches to see how the time of day affects the virus: either she changes the time that she infects hosts or she uses a host with disrupted circadian rhythms. Circadian rhythms can be disrupted using drugs or genetic modification.

Rachel is also investigating whether viruses can manipulate our body’s clock. For these experiments, instead of using viruses that emit light, she uses cells that emit light in time with their circadian rhythms. She can then compare the patterns in light emission before and after infection to see if the virus has any effect. When looking at whether a virus is able to manipulate the circadian rhythm of whole animals, she monitors whether their behaviour changes before and after infection.

Once we understand how the viruses interact with our circadian rhythms, we may be able to use this new knowledge to our advantage during treatment, applying an approach called chronotherapy. This approach uses current drugs, but matches the times at which they are given to a patient with their biological clocks and is being researched to test its effectiveness in the treatment of cancer and diabetes, for example. Rachel thinks the same could apply when treating a viral infection: “You can potentially envisage that when you give an antiviral drug might be very important, particularly with persistent or long-term viruses.”

Rachel also suspects that how infectious we are when we have a virus may depend not only on how long we’ve been infected and how long the virus has had to replicate, but also on the time of day. If this were true, we may be able to make changes to the ways we try to prevent viral disease transmission on a population scale.

Calum Wiggins

Calum is a member of the Wellcome Trust’s Graduate Development Programme.

Image credit: Richard Jones on Flickr under CC BY 2.0
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Conflict and Co-operation in Bacterial Communities

ResearchBlogging.orgLike hPolymicrobic_biofilm_epifluorescenceumans, bacteria in nature often live in communities. New research studying the interactions within these microbial communities shows how bacteria can co-operate with each other to resolve a form of social conflict.

Many bacteria live stuck together on surfaces, in communities known as biofilms. These masses of bacteria, sugars, proteins and fragments of DNA are found everywhere – inside pipes, on medical implants and in your gut, to name a few examples – and they are how most bacteria exist in nature.

Like any community, bacteria within biofilms have competing interests and needs. On the one hand, bacteria on the edges of the biofilm are vulnerable to external attack – from antibiotics or other bacteria – while those on the inside are protected. On the other hand, these peripheral bacteria have better access to a key commodity: food. So much so that, if left unchecked, cells on the outer edges would consume all the available nutrients in the environment, causing the interior bacteria to starve and die. Continue reading

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Microbe Talk Extra: Flu Fighters

56f2R_WX For this Microbe Talk Extra, we went to the Royal Society’s Summer Science Exhibition to meet the Flu Fighters – scientists working on new ways to fight and diagnose influenza. Dr Holly Shelton works at The Pirbright Institute on the genetics of the flu virus. She talked to us about how different strains of flu infect different species, from bats to birds to humans. We also hear about new devices which allow farmers to test their poultry for bird flu – and get instant results. No animals were harmed in the making of this episode, but a robot chicken was rather disgruntled. Don’t forget, you can subscribe to Microbe Talk on iTunes. You can also find us on Soundcloud and Stitcher.

Anand Jagatia

Image credit: Flu Fighters
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Profile: Dr Marie Anne Chattaway

Marie2Society member Dr Marie Anne Chattaway works as a Clinical Scientific Lead for Public Health England (PHE), based in London, UK. We spoke to Marie about her career, her work for PHE and how working abroad can expand your scientific horizons.

What does a typical day look like for you?

I’ve recently started in a new position in the Gastrointestinal Bacterial Reference Unit (GBRU) at PHE and provide leadership and expertise in managing the delivery of reference services across GBRU and providing expert advice. When there’s an outbreak of a bacterial foodborne pathogen – Verocytotoxin-producing E. coli (VTEC) or Shigella for example – my job is to help with outbreak investigation, identifying and typing the strains involved. Although I’ve moved into a more managerial role now, it’s all hands on deck with the laboratory work when there’s an emergency outbreak. I am also heavily involved with the implementation of Whole Genome Sequencing in GBRU as a reference service and the restructuring of our department following on from the change in technology.

What does the GBRU do?

GBRU is the National Reference Laboratory for a range of gastrointestinal pathogens including Campylobacter, Salmonella, Shigella, VTEC and Listeria. The unit works at local, regional, national and international levels to reduce the impact of food, water and environmentally-borne illnesses on people’s health. For example, when a patient with a gastrointestinal infection provides a sample, a hospital laboratory usually carries out the primary diagnostic work to isolate the causative pathogen. If this is a bacterium, the isolate will be sent to us for identity confirmation and for more detailed characterisation or typing to be carried out, typically using molecular methods and increasingly whole genome sequencing. These detailed results are sent back to the hospital but are also used for national surveillance in order to monitor gastrointestinal infectious disease trends throughout the country. Continue reading

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World Hepatitis Day 2015

Print28 July is World Hepatitis Day, which aims to promote better awareness and understanding of viral hepatitis, and ultimately seeks a world free from the disease. Every year 1.4 million people die from viral hepatitis but many of these deaths could be avoided. The message for this year’s campaign is: “Prevent Hepatitis: It’s up to you”.

Hepatitis is an inflammation of the liver. There are five different types of viral hepatitis – hepatitis A, B, C, D and E – and each is caused by a different virus that can lead to acute (short-term) or chronic (long-term) infection. This inflammation can cause scarring, liver failure or liver cancer – in fact, hepatitis causes around 80% of all liver cancer cases worldwide.

Hepatitis is one of only four diseases that has its own WHO global campaign day, (along with AIDS, malaria and tuberculosis), highlighting the scale of the problem it poses for public health. 28 July was chosen as the date for World Hepatitis Day in honour of Baruch Blumberg, who won the Nobel Prize for identifying the hepatitis B virus and also developed a vaccine for the disease. Continue reading

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Microbe Talk: July 2015

DSC_0115This month’s episode of Microbe Talk is something a bit different – the first in a two-part special on forensic microbiology.

In part one, we’re exploring the microbes of death and decay – and how they can be used by forensic scientists to work out when and how someone has died.

We spoke to writer Mo Costandi about his recent experiences visiting body farms in Texas, where scientists study the process of decomposition. Mo wrote an article for the Wellcome Trust’s Mosaic on the subject (which is well worth reading), so we asked him to the Society’s offices to find out more about what happens to our bodies after we die.

We also hear from forensic scientist Dr Gulnaz Javan, who is conducting research into the “thanatomicrobiome”, or microbes of death, at one of these facilities. Gulnaz and her team take samples from cadavers and the surrounding soil in order to study the microbial communities present at different stages of decomposition. She talked to us about a recent paper from her group that discusses their early findings.

This episode contains descriptions of decomposing human corpses.

 

You can see a gallery of some photos which Mo took at one of the body farms below:

Show notes:

Don’t forget, you can subscribe to Microbe Talk on iTunes. You can also find us on Soundcloud and Stitcher.

Anand Jagatia

Image credit: Mo Costandi
Music: Chris Zabriskie under CC BY 4.0
Sound effects: “BunchOfFlies” by HerbertBoland under CC BY 3.0, “Countryside in Texas, insects and birds” by felix.blume under CC0 1.0
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