Re: PCR and microtomy


To decontaminate material for specific PCR sterility is not needed. 
Actually, ethanol, autoclaving or even flaming do not destroy DNA but 
actually can fix it. Decontamination is achieved by wiping with 
commercial products like "DNA away". Cheaper but also effective is 
immersing in 10% bleach for at least 1 minute and then rinse in ddH2O. 
Irradiation gets the job done but is not practical for histology.

Having the techs using all sterile/decontaminated gloves and material is 
not necessary unless there is risk of contamination of the samples with 
human DNA from the techs (hair, skin, etc..) (this is if target sequence 
is human). If this is not the case, just focus on the risk of cross 
contamination when cutting different blocks (decontaminate blade and 
forceps as above, and if possible change water in the floating bath). 
Nucleases are usually not a problem  with this kind of material (I 
assume target is DNA not RNA), but to play on the safe side gloves are 
strongly recommended.

Hope that it helps,


apagan wrote:

> We have been asked to cut 20 micron sections from paraffin blocks for 
> PCR.  My question is how do others clean/decontaminate the microtome, 
> blades, etc that are used.  Do you also sterilize any forceps or other 
> instruments used, and does the tech wear sterile gloves?  Since the 
> tissue was not treated specially up to this point (we did not know of 
> the pcr request) does it really matter that everything is sterile 
> now?  We did purchase DNAase and RNAase free vials to put the ribbons in.
> Audrey Pagan
> Laboratory Manager
> Lakewood Pathology Associates
> 1200 River Ave.  Suite 10E
> Lakewood, NJ   08701
> 732-901-7575  ext. 102

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