If you use RNeasy mini kit, you can follow its RNA cleanup protocol to concentrate the pooled RNA on one spin column, treat with DNase, and elute the pooled RNA in 50 ul.
My qPCR protocol uses 2 ug total RNA for cDNA synthesis, but only 2 ul of 1:10 dilution of the cDNA per tube are used for qPCR. So 0.5 ug total RNA may be sufficient for cDNA synthesis. You may dilute cDNA 1:2 instead of 1:10.
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