cDNA synthesis

[ifhmn]

I have few samples with different concentration of RNA where the highest can be up to 500ng/uL and the lowest is around 40ng/uL. I used cDNA synthesis kit from bioline. Do i have to standardize my starting RNA for cDNA synthesis? this is because I used 1ug of RNA for the samples with high concentration and 0.4-0.5ug of RNA for the samples with low concentrations. I'm going to use my cDNA for PCR and RT-PCR, and cloning.

[relaxin]

If you want to show the difference of gene expression using RT-PCR, you need to start cDNA synthesis will the same amount of total RNA. Samples with low RNA concentration need to be concentrated by ethanol precipitation, otherwise the volume will exceed that of the RT reaction.

If you are only interested in cloning of the PCR product, normalization of the RNA concentration is not critical.