Dear Bhakti,

You can store DNA and Protein for a considerable period at -20 deg C but RNA is not that stable. You can either store it at -80 deg C or reverse transcribe it into cDNA and store at - 20 deg C. Freeze thaw could be devastating to these macromolecules, so its advisable to store them in aliquot (Especially protein and RNA). Good luck.

Dear Bhakti,

If you are willing to store your DNA and RNA for more than 6 months you have to disolve it in TE buffer and store it 4 C or -20.

Dear Bhakti,

In agreement with Sathyan considerations, I think that you must be careful with RNA samples. But, paradoxically, RNA is very stable, even if submitted to high temperatures. The major problem is the presence of RNAse in the environment, that quickly degrade RNA molecules, mainly if the sample is not stored in lower temperatures. Hence, is very important to work under free RNAse conditions, e.g. using "RNAse away" treated gloves, mask and RNAse free tubes during the manipulation of the samples. In addition, is important to maintain the samples under ice cold conditions, to aliquote the final product of extraction and, finally, to store it at -80ºC.

Good luck.

Sorry to say I disagree (in part) with previous replies, not on the stability issues of the three fractions, but how to practically handle them. The best way to store the three fractions obtained with Trizol (or similar brands), is to keep the 3 fractions unpurified, either in whole Trizol, or as 3 separate fractions obtained right after phase-separation, just freeze (preferably -80 C, but -20 C also worked for us to recover RNA and/or DNA after >12 years!). It is actually less work at the day of the experiment, in your case when obtaining the amastigotes. The upper phase (containing RNA) is nicely protected for years because the guanidinuim salts protect it. Finally, transcribing RNA to cDNA will hamper or exclude the possibility to use novel technologies, e.g. RNA-Seq, nCounter,... and limit your future options.

Oh yes I completely agree with Weyenberg. If you don't want to purify your macro molecules instantly, you can preserve them in TRI reagent for ages at -20 deg C.

I first tried to get the protein from TRI Reagent. It worked very good for RNA but it didn't work for DNA and protein. For DNA I had to develop separate protocol which works well. The problem with protein is still unsolved. Protein isolation with RIPA Buffer failed to keep the proteins intact even when preserved at -20 °C. But it worked if used in fresh. Now I want to see the result with protease inhibitor cocktail, if it can be stored for long at -20°C.

Dear Bhakti Laha,

I'm having problems to extract DNA from Leishmania using TRI reagent. I saw that you developed a sepate protocol for that. What do you do?