[Histonet] TUNEL stanining - trouble with background

[Aleš Kladnik]

Dear Histonetters!
For detection of fragmented DNA in tissue sections I'm using TUNEL kit 
from Roche, with fluorescein labeled nucleotides. The tissue is corn 
seed, and the problem is that fluorescent nucleotides stick massively to 
amyloplasts (starch grains). The reaction is not specific, since they 
don't even contain visible amounts of DNA (determined by DAPI staining).

Did anyone of you experienced such a problem with non-specific binding 
of nucleotides to tissue structures?

I've found a reference stating that the problem might be due to calcium 
in the tissue structures, and the non-specific binding of nucleotides 
may be abolished by treatment with EDTA or citric acid:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8669464&dopt=Abstract

Did anyone try this and willing to share their experience on this? Thank 
you!

-- 
Aleš Kladnik
University of Ljubljana, Biotechnical Faculty, Department of Biology
Večna pot 111, SI-1000 Ljubljana, Slovenia
tel: +386 1 4233388, fax: +386 1 2573390
url: http://botanika.biologija.org/
skype: fridjo, msn: aleskladnik <@t> hotmail.com