How much tissue would be required to do RNA-seq analysis on a single organism? More specifically, if a person wanted an RNA-seq analysis of expression for a single organ, how much tissue would they need to donate?
Our DNA core wants 1.5 ug of RNA. I find that I can obtain that amount from a standard Trizol prep from about 1 mg of Arabidopsis floral tissue. I usually double or triple what I harvest to account for random variation in yield.
The Illumina TruSeq RNA Sample Prep Kit v2 with oligo(dT) selection recommends an input of 100 to 1000 ng of total RNA in a volume of 30 ul for library construction.
The Epicentre TotalScript RNA-Seq Kit (Epicentre cat# TSRNA1296) is designed for an input of 1-5 ng of total RNA in a volume of 12 ul to a RNA sequencing library.
Whether you will get a complete picture of a whole organ from such a small slice is an entirely different question. The brain has different regions, with different gene expression.