Hello honorary parasitologists,
I know there has been a bit of radio silence on my part and I apologise, summer was calling me and there was a lot of stuff to get through before I could escape on annual leave.
I'm back now and picking up where we left off. Perhaps you are wondering what happened to all those samples we collected in Tanzania in May (see previous posts). Well wonder no longer, I am about to reveal all.
A quick recap of our collecting in Tanzania:
- We collected miracidia, the parasite larval stage from infected children, and stored them onto special paper (called Whatman® FTA cards) that stores their genetic material.
- We also collected the intermediate host snail from potential transmission sites on the banks of Lake Victoria.
- Finally we collected cercariae, the larval stage from infected snails, and stored their genetic material on the Whatman® FTA paper.
Visiting schools to identify infected children, collect the schistosome larval stage (miracidia) and treat the children.
Snail collecting on the banks of Lake Victoria.
Collecting cercariae, the Schistosoma larval stage, from infected snails.
Whatman® FTA cards store the genetic material of schistosome larvae collected from infected children and/or snails.
Storing our collected schistosome larvae on Whatman® FTA cards is ideal for us because:
- We avoid storing them in flammable liquids like ethanol.
- We avoid having to bring back live, infected snails.
...two things that aiports and customs really don't like!
The Whatman® FTA cards lyse (break) open the parasite cells and lock the genetic material onto the card, keeping it stable and safe at room temperature until we need to use it. So this means we can bring back our samples safely in our suitcases. Hurrah!
The snails, on the other hand, have to be stored in glass tubes with ethanol, so these we have to leave behind in the safe hands of the National Institute for Medical Research, Mwanza. Our collaborators take good care of them until we can arrange a courier service to bring them to the Museum.
Once back in the UK I hand over all collected samples and forms to the wonderful SCAN,Schistosomiasis Collection at the Natural History Museum, team. SCAN takes care of the thousands of schistosome samples collected from all over the world and stored at the Museum. This colleciton is very precious and in high demand for lab-based scienists researching the genome of the parasite and host snail in search of new ways to understand and control the disease.
SCAN cares for collected samples and manages all the associated data, such as:
- GPS coordinates - so we know where the sample has come from.
- Collection method - what technique was used to collect the sample?
- Date of collection - how old is the sample?
- Storage medium - is the sample stored on Whatman FTA card or ethanol or any other storage tool?
- Data on the parasite host - did the sample come from an infected human, cattle, snail? If a snail what species? If a human what age? Gender?
And lots more.
The fieldwork forms I fill in when collecting samples in Tanzania. I hand these forms over to the SCAN team along with all my collected samples. They then have the frustrating task of trying to decipher my handwriting.
You have met two members of the SCAN team in my previous posts; Fiona Allan, who acted as our fieldwork photographer whilst helping me in Tanzania and Muriel Rabone, who came to my rescue after Fiona had to head back to the UK. There is just one more person for you to meet; the ever-patient and resourceful Aidan Emery, who manages SCAN.
Fiona and I going through my fieldwork forms and samples - "what have you written here? It's illegible!" Oops!
As you can see there is A LOT of data that goes with each and every schistosome/snail collected and researchers need to have all this information when analyising a parasite or snail sample. SCAN ensures that all this information is properly entered into a database and linked with the samples stored in the Molecular Collection Facility (more on this in a bit).
The SCAN team has even created a wonderful online catalogue of all the collected samples they care for, along with all the data linked to each sample. This greatly assists researchers from all over the world, allowing them to have a look and see what samples are available to them.
Fiona and Aidan storing the Tanzanian schistosome samples collected onto Whatman® FTA cards. Fiona is showing off the little blue booties we have to wear in the Molecular Collections Facility to avoid bringing in contaminants or anything that could harm the hundreds of thousands of precious samples stored there.
The SCAN team takes a photo and measures the size of every snail that arrives from our African collaborators. In order to extract the DNA from the snail for molecular work the shell must be crushed and removed. It is good to have a picture of what the shell looked like before doing so.
The Molecular Collections Facility is a crucial facility in the Museum, as it has all the equipment necessary to keep molecular and genetic samples (such as our schistosome samples) stored safely, stabily and for a long, long time. What equipment am I talking about? I mean: -80 freezers, nitrogen tanks, air-tight cabinets, equipment to release/elute genetic material from stored samples, centrifuges, pipetting robots, you name it. It is run by the very helpful Jackie Mackenzie-Dodds.
Jackie runs the Molecular Collections Facility where all our schistosome samples are stored. All the freezers and nitrogen tanks have alarms linked to them to make sure they continue to function correctly. If one fails an alarm goes off on Jackie's mobile phone so no matter where she is she is immediately notified and able to respond.
Jackie is showing me the liquid nitrogen tanks in the Molecular Collections Facility. Whilst nitrogen in gas form is harmless, liquid nitrogen is very, very cold and any contact with it can cause severe frostbite, even freeze your arm off. Also as it boils it uses up a lot of oxygen in the air, which can lead to asphyxiation. So oxygen monitors are always used. Its incredible freezing ability means it is very effective at storing rare, degraded and old tissue samples.
So there you have it, all our samples are archived carefully until we are able to perform the molecular work we need to do for species identification and to determine how the genetic diversity of the parasites is being affected by treatment control programs. My next couple of blood fluke posts will be about the techniques we use to do this. So read up on Polymerase Chain Reactions (PCR)... it does feature!
Fiona and I have managed to decipher my handwriting! Hurrah! The samples are saved!