In article <34B11610.46F9 at west.bidmc.harvard.edu>,
mkoziel at WEST.BIDMC.HARVARD.EDU (Margaret Koziel MD) wrote:
> Has anyone compared different methods for freezing tissues for optimal
> preservation of mRNA - is it better to freeze in liquid nitrogen,
> Trizol?
I've tried both ways and my preference is to freeze in some form of phenol
buffer (RNAzol, Trizol, RNA-Stat, etc).
The reason for this is simply that I find it easier to render the tissue
into its component cells while it is still fresh, prior to lysis. RNA
keeps with no appreciable degradation for at least 3 years at -40 C (and I
suspect, much longer) in RNA-STAT. It also keeps me from having to remove
small pieces of shredded aluminium from my samples. :-)
If you are going to freeze tissue in liquid nitrogen, you need to freeze it
as quickly as you can and perhaps more importantly, keep it as cold as
possible when smashing up the frozen tissue. If the tissue thaws
significantly not only can you get a fair amount of degradation but your
yield falls off as RNA is lost in the gooey protein/DNA sludge that rapidly
forms.
Cheers, Mark