It is better to use ultrapure water, however for in-situ hybridization (or any procedure where you do not need enzymatic activity) you do not have to treat the water with DEPC+ autoclave or autoclave any of your glassware, but instead add an RNase inhibitor to all solutions. This saves a lot of time. Such inhibitors, unlike those that are added where enzymatic activity is required, are relatively cheap, one example being a new product from Sigma called "protect-RNA".

Dorit

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From:  Heike Grabsch
Sent:  יום שני 17 מאי 1999 04:53
To:  histonet@Pathology.swmed.edu
Subject:  water quality

A question for people who are doing studies with RNA like RT-PCR and in 
situ hybridization for RNA:

what sort of water do you use?
a) regular distilled water that is treated with DEPC and then autoclaved
or 
b) ultrapure water (f.ex. MilliQ)that is treated with DEPC and then 
autoclaved

one of my collegues says that there is no need for ultrapure water, but I 
would like to have some more opinions before I cut down my standards. (In 
the lab where I was trained in molecular biology everything (also non-RNA 
buffers etc) was prepared with ultrapure water.

thanks for some arguments

Dr. Heike Grabsch, Germany