I have RNA samples stored at -70º, that have been extracted from animal blood, excrements, urine and saliva about 3 years ago. I wonder if this RNA samples are stable to use in a RT-PCR assay.
Hi Thomas and Nahid. The freezer was working fine and RNase out were added to the extracted RNA. So I believe I could use it.
Hi Leonardo, the RNA is stable for several months or even years if stored at low temperatures (ie -20 degrees). Several cycles of freezing and thawing may affect yours RNA stability. However, the only way to asses if the quality of the RNA is good for the RT-PCR is to quantify it (260/280 and 260/230 ratios of 1.8-2 and 2-2.2, respectively, indicate a good quality RNA with low contaminations) and run an equal amount (ie 0.5-2 ug) in agarose gel.
Must be use positive control to be sure about sepific genome
I agree with Matteo, freeze thaw cycles definitely affect RNA quality and RNA degradation can easily be monitered by Gel electrophoresis and by the spectrophotometre.
I hope by now you must have got desired results in your RT-PCR assay
I agree with the others. Most important are 1. the amount of feezing and thawing processes and 2. the storage temperature (-20°C are more than enough I'd say). If the samples were kept frozen all the three years, there shouldn't be any problem with the assay.
Hello
I think as long as you didn`t made several freezing and thawing cycles will be Ok, and with good control on the temperature of freezer during that period
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