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DNA extracted

posted May 6, 2012, 8:55 AM by Karen Dunmall
DNA was extracted from 41 of the 231 salmon returned for reward in 2011.  DNA is in the cells of the salmon.  I took muscle and fin tissue when each fish was sub-sampled so that I could get the DNA from the salmon.  These samples have been frozen in ethanol to preserve them until it was time to extract the DNA.  

I followed a "recipe" to get the DNA out of the cells:
1) Cut a small piece of muscle from the whole sample.  The amount of tissue needed is about the size of a finger nail clipping!  
2) Put the tissue in a vial and add an enzyme that breaks apart the cell walls (called lysing)
3) Heat it up and gently shake for 4 hours; there is a machine that does this!
4) Add a buffer (a liquid made up of salts and detergents) and more ethanol.
5) Spin in a centrifuge (fancy name for spinner) at a set spinning speed for a minute
6) Add more buffer
7) Spin
8) More buffer...
9) Spin for longer and faster
10) More buffer... different kind this time.
11) Spin one last time
12) What is left in the vial is DNA!  It is in a clear liquid; looks like water.  Refrigerate or freeze until ready to use.

DNA is so small, you can't see it.  So, I did a test to make sure the recipe worked and we actually got the DNA out of the cell.  I took a very small amount of this liquid and added some special blue dye (called a marker) that actually attaches itself in the DNA.  This marker glows under UV light so we can see the DNA if this marker is attached.  I then made the liquid with the DNA and the marker spread it out in a gel (like clear jello but made out of seaweed) which sorted the DNA by the size of the piece.  The longer pieces couldn't move as far, so they show up as a band near the beginning and the shorter pieces moved further through the gel and show up as a band further away from the beginning.

This photo is of the gel under UV light.  Each rectangle is a different salmon.  The yellow box is a chum salmon from Aklavik; the pink box is a chum salmon from Tsiighetchic.  The bright lines in each box are the DNA.  Shows that the recipe worked!  We extracted DNA from these 41 salmon.  Next step: get DNA from the remaining 170 salmon.


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