Functional Genomics & RNAi

RNAi Answer Archive

Experts in the field of RNAi have answered your questions. You will find your answers here.



Can I resuspend dried siRNA duplex pellet in RNAse-free water instead of 1 x TE?
I want to lyse plant cells at various stages and analyze the miRNA (siRNA) population. What vector can I clone the whole population into and how much starting material do I need to clone?
What is the best strategy to elucidate individual siRNA sequences from a heterogeneous population (pooled siRNA)?
Which transfection reagent is best suitable for siRNA transfection in to primary murine peritoneal macrophages?
Is the system GP2-293 and pVSV compatible with MISSION® RNAi Lentivirus?
I am wondering if you sell any RNAi for the plant GUS gene (GUSb)? Do you sell any GUS RNAi controls for plant cell work?


Can I resuspend dried siRNA duplex pellet in RNase-free water instead of 1 x TE?
siRNA is dried down in the presence of buffer, therefore, should be resuspended in molecular biology grade water (DNase and RNase free), Sigma-Aldrich® product number W4502.

siRNA Buffer:
Potassium Acetate (100 mM)
HEPES (30 mM)
Magnesium Acetate (2 mM)


I want to lyse plant cells at various stages and analyze the miRNA (siRNA) population. What vector can I clone the whole population into and how much starting material do I need to clone?
Please refer to the detailed miRNA Cloning protocol from Dr. David Bartel's lab. His main research focus is miRNA in plants.


What is the best strategy to elucidate individual siRNA sequences from a heterogeneous population (pooled siRNA)?
The best method would be to use a sequencing technology that gives high coverage and works well on short sequences. Another option is to subclone the population into a vector, followed by sequencing. If the constituents of the population are known, a chip-based detection method may also be used.


Which transfection reagent is best suitable for siRNA transfection in to primary murine peritoneal macrophages?
Non-adherent cells, such as macrophages, may only achieve highly efficient transfection by using electroporation; however, MISSION shRNA lentiviral particles may be used to transduce primary cells, even non-adherent cells.

A protocol for transduction of suspension cultures may be found on the TRC Protocols Page


I purchased several panels of MISSION RNAi Lentiviral plasmids in bacterial stock. Using purified plasmids, GP2-293 cells, and pVSV plasmid, I tried to produce lentivirus, but in vain. The problem is that after infection, puromycin resistance clones have never arisen so far. Is that system (GP2-293 and pVSV) compatible with MISSION RNAi Lentivirus?
That cell line is NOT compatible and cannot be used to produce virus with the MISSION shRNA library. You'll need to use packaging vectors derived from HIV. We recommend using our SHP001 packaging mix for optimal high titer virus production.


I am wondering if you sell any RNAi for the plant GUS gene (GUSb)? Do you sell any GUS RNAi controls for plant cell work?
While Sigma has no current pre-designed RNAi product against that particular gene target, it is possible for us to custom manufacture a synthetic siRNA for you. If you have a particular sequence in mind (i.e. sequence from a publication that was shown to elicit a good gene silencing response), or we could design a series of sequences for you based on our proprietary Rosetta design algorithm...and then have those synthetic RNAi's made for you.
Learn more about siRNA

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