0
$\begingroup$

I'm reading some papers for the first generation sequencing methods and some earlier than them, like Ray's Wu first time DNA sequencing from a λ phage virus cohesive 5' ends. Ray Wu, like Maxam-Gilbert and Sanger, used 32P / 3H to label either dNTPs or DNA molecules.

But what happens if you add such radioactive materials inside a test tube with DNA and other molecules like DNA Pol I? For example, 32P emits electrons at 1.709 MeV. Couldn't these high energy electrons harm the DNA or Pol I molecules (bonding destruction), that are present nearby at the time of reaction?

$\endgroup$
0
$\begingroup$

Experimentalists pretend, or act as if, those effects are negligible, or miniscule. One could calculate the number of DNA or protein molecules that are affected, by plugging in the specific activity of the dNTPs, the concentration of the potential targets, the volume of the reaction, and the time.

Certainly if you create radiolabeled nucleic acids and store them, then over time those strands will undergo scission as the phosphorous emits it's beta particle. Some of the neighbouring bases might be hit.

If you pulse label growing bacteria or phage you can then mutagenize and select for mutants in interesting pathways (this was called radiosuicide and was invented by Clarence Fuerst).

It is also possible to label bacteria and feed them to C. elegans such that the progeny of those worms will contain new mendelian mutations induced by the radioactive DNA in their mothers' germline.

$\endgroup$
  • $\begingroup$ Thank you very much. Your answer is very informative. I liked the use of "pretend" verb. Do you have any paper in mind "counting" the destroyed molecules from such chemical agents? $\endgroup$ – F.N Oct 25 '16 at 18:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.