Thank you so much Daniel

links are so helpfull

all the best

I've extracted total RNA from cell line using TRIzol (Invitrigen) and measured micro RNA volume with Aligent 2100 Bioanalyser electropherogram. Interestingly the concentration was pretty. I think You can isolate microRNA using TRIzol

Dear Mira,

There is a difference between kits from different suppliers. Trizol RNA isolation on its own ( without subsequent column isolation) will isolate all species of RNA. In many of the column based kits most of the small RNA is washed off while retaining the larger total RNA and subsequently eluting it. It has to do with the formulation of the wash/sample buffers.

We have had good experience with some kits ( e.g. http://www.clontech.com/US/Products/Nucleic_Acid_Purification/RNA/MicroRNA/Tissue) and there are special kits on the market that let you isolate small/miRNA and large RNA separately or together, and in some cases DNA or protein as well.

You probably want to check the manual for any kit you want to use before you purchase to make sure they say you can isolate small/miRNA.

good luck

Many total RNA kits are designed for recovering total RNA>200bp. I am not sure about the kit you are using right now. Call the company or you certainly can modify the protocol to recover micro RNA or just buy miRNA kits. The key is the amount of the ethanol in the lysis and wash buffers, which should be >60%, otherwise you will lose small RNA. Here are the protocols with modification steps (step 3, 4 and Option 2) for recovering and enriching micro RNA:

http://www.enzymax.net/columns/Tini%20column%20RNA%20kit.pdf

(Pay attention on step 3 in this protocol: add 1/2 volume of ethanol)

Or follow this protocol to recover total RNA including miRNA (>17nt):

http://www.enzymax.net/columns/Tini%20column%20MiRNA%20Kit.pdf

(Pay attention on step 3: add 1-1.5 volume of ethanol)

Or click 700 and 701 or EZCR302 from the following link if you can’t open the files above

http://www.enzymax.net/columns/RNA_isolation.htm

Good luck :-)

Michelle Wu makes a good point. You may waste time and money by assuming that kits for isolation of total RNA will also give you microRNA.

For useful isolation of microRNA, the amount of which is very small compared to total RNA> 200bp, kits designed for isolation of microRNA should be used.

We have used kits from Sigma or Qiagen, which have yielded microRNA isolates well suited for microarrays or qRT-PCR.