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Asked by to Ben on 18 Jun 2014. This question was also asked by .
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Ben White answered on 18 Jun 2014:
Hi @shivanjalinp, great question and hopefully not too unexciting an answer!
Depending on what the sample is, we generally need to keep it cool or frozen…DNA is kept in a freezer at -20 °C, this is pretty much the same as the freezer you will have in your home.
RNA will degrade very quickly if it gets hot (anything above freezing), and naturally doesn’t stay around in our bodies for long. For this we use freezers that can keep the RNA frozen at -80 °C. This is so cold that if you touch the inside of the freezer (or tube) with your skin you will likely burn yourself; I know this personally.
Both DNA and RNA will last years when stored in the right conditions, and freezing is one of the most effective ways of keeping them intact.
In fact, it’s so good at keeping things stable that scientists were recently able to revive an ice age flower that had been frozen for 30,000 years.
http://www.telegraph.co.uk/science/science-news/9094716/Ice-Age-flower-revival-that-could-lead-to-resurrection-of-mammoth.html
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Comments
Rebecca commented on :
I also keep my bacterial samples frozen. We can store the bacteria at -80’C for many years and then take them back out and grown them again! We do have to be careful though, as the stress on the bacteria of freezing it and thawing it can cause very small changes in its genome. If we then sequence it after it has been stored for a long time or taken in and out of the freezer many times we need to remember that there might be a few small changes like 1 change in 2,000,000 letters (bases) of the bacterial DNA!
Heather commented on :
Because I often work at sea to collect my samples I will sometimes store mine slightly different.
Like Ben said, RNA can degrade very quickly so it is important to get your samples as cold as possible so when I am on the boat I do this by placing my samples into a liquid nitrogen canister which is approximetely -210C! After this I have to transit them home on an aeroplane and as you can imagine something which is so cold can be dangerous so we use something called a dry shipper. We fill a canister with liquid nitrogen the day before we want to use it to make the canister REALLY cold. We then empty the canister of all the liquid nitrogen hence why it is called a DRY shipper. The canister will stay really cold for several days to allow us to take the samples back still frozen.
Because taking samples in a dry shipper is very expensive any samples I want to take home I store in ethanol and once I have extracted the DNA I keep it in -20C.