extraction and PCR problem

[Valérie Moreau]

I extract DNA from whole mussels (0.2 - 0.7 mm) that have been in ethanol 
since October 1999. The extraction protocol is the usual phenol, 
phenol-chloroform-isoamylalcohol, and then chloroform-isoamylalcohol before 
ethanol precipitation.
The problem is when I run PCR (target gene: glu-5 (242-380 bp)) with fresh 
or frozen mussel, everything works well. But with DNA extracts from mussels 
in ethanol, PCR doesn't work. It smears with no band.
Could it be possible that ethanol preservation has a destructing effect on 
DNA structure? Is there a modified protocol for extracting DNA from ethanol 
preserved samples? Do I need to do something with the extracted DNA before 
runing PCR?
Thank you very much.
Valerie Moreau
valerie.moreau at agr.gouv.qc.ca


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