Isolation of RNA by silica?

Shahram Mori smori at
Wed May 25 13:59:02 EST 1994

(Paul Taylor) pgt (pgt at wrote:
: Please Help!!!!!
: I am trying to find out if the Guanidinium thiocynate/ Silica method of DNA 
: extraction is also suitable for efficient extraction of total RNA.
: My wish is to simultaneously extract both RNA and DNA by this method.
: I am assuming that RNA will not be degraded by any of the reagents employed 
: and that the sugar phosphate backbone of RNA has a similar affinity for 
: thiocyanate.
: I have noticed that Bio101 geneclean kits claim to remove RNA without the 
: use of RNAse enzymes. Does the same apply to all silica based extraction 
: methods or is it peculiar to Geneclean's reagents?

: Also, what is the general level of stability of RNA with respect to 
: temperature, freeze-thawing, UV light etc.

: Comments appreciated, Thanks.
: Paul G. Taylor (Research Fellow: Molecular Archaeology)
: DNA Laboratory, Department of Palaeontology, Natural History Museum
: Cromwell Road, LONDON SW7 5BD
Dear Paul,
Using guanidine thiocyante is my method of choice. it can disrupt and at the
same time inhibit RNases and Dnases. The glass fines method is not an
efficient way to get RNA from cells because the latter doesn't bind well
to it. USE RNAse FREE WATER all the time.
Later if you want to isolate either RNA or DNA, use Rnase free DNase and Dnase
free Rnase respectively.
About storage; I think the best way to store RNA is at Neutral PH in ethanol
precipitated form at -70 C. I think it can last between 6 to 10 months.
I store mine in aliquots of DEPC-treated H2O at -70.
Shahram Mori
Program in Molecular Biology
Dept. of Chemistry Box 3C
NMSU, Las Cruces NM

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