First, let me make perfectly clear that I am not a member of the field of science so I hope this question makes sense…
I have just returned from donating blood at my local Red Cross. Mr. Ruby and I were discussing the act of donating blood for the use of strangers and the topic of DNA came up.
Isn’t my DNA found in my blood? And when it’s injected into the recipient, does my DNA survive?
Hey Ruby,
DNA is most definitely found in the cells of your blood. And yes, when it’s injected into the recipient, the DNA remains intact. This is necessary for the proper functioning of the cells. However, the cells in the blood you donated have a finite lifespan. Once they die, their DNA will be degraded. Barring further transfusions, the only source of blood for the recipient is his/her bone marrow. Therefore, all the cells in his/her blood will once again contain only his/her DNA.
-Apoptosis
Don’t they often only transfuse blood plasma? Does this still contain any DNA?
Plasma may contain some relics of DNA and the odd cell that isn’t centrifuged out. It would be quickly degraded.
To expand a little, the nuclear DNA in blood is mostly in the white blood cells. Mature red blood cells have no nuclear and hence lack nuclear DNA. (I would guess they have some mitochondrial DNA).
Also, leukocytes (with the exception of T cells) have about a 48 hour life span. However, with transfusion they would be attacked as foreign and I doubt they would last for more than a few hours. So if you are thinking of commiting a crime following a transfusion and pinning it on the donor you can pretty much forget it.
Well, personally commiting a crime wasn’t part of the discussion but the credibility of DNA as criminal evidence was.
I think you’ve cleared up my confusion, though. Thanks, all!
Hey Colibri,
Mature erythrocytes also lack organelles, and therefore do not possess mitochonrial DNA.
-Apoptosis
Thanks, I wasn’t aware they lost all organelles.
In our lab, we regularly extract useable DNA from plasma, though the yield is usually significantly less than from blood (obviously). The separation processes aren’t perfect. A fair amount of cells get left behind.