[Histonet] Promega TUNEL assay...Or any TUNEL Assay

[JR R]

I don't like TUNEL on FFPE tissue.  Way too many false positives. And yes, I've tried titrating down the concentration of TdT and substrate.

Then I found out that formaldehyde causes DNA strand breaks.  In other words for your positive control, you can used formalin fixed tissue, because formalin has the same effect as DNAase.

The other thing problem with TUNEL on FFPE tissue is that the TUNEL assay detects DNA strand breaks.  Any tissue, fixed of frozen, that is on a slide HAS been subjected to another procedure that causes double tranded DNA breaks--a procedure called microtomy. When a microtome bvlade passes through the nucleus of a cell it breaks a lot of DNA strands. And every one of them is detectable by TUNEL.

I've heard of people getting rerasonable results with whole cells and frozen tissues, by for FFPE tissue, my current philosophy is: It is an assay that CANNOT work, even in principle.

'Course, I've been wrong about other things,

I'm open to persuasion.



Jerry Ricks
Research Scientist
University of Washington
Department of Pathology

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