RNA AMPLIFICATION
In many cases researchers can obtain only a limited quantity of total RNA from each sample. When less than 5 ug of total RNA are available, one solution is to use an RNA amplification procedure to increase the amount of starting material before labeling. The CAT offers RNA amplification for these situations using a modified Affymetrix labeling protocol. With these methodologies as little as 50-100 ng of total RNA can be amplified to provide sufficient aRNA for labeling and hybridization.
These kits use modifications of the Eberwine procedure (Van Gelder et al., (1990) PNAS 87:1663-1667)
One caution when using RNA amplification for labeling: although the Eberwine procedure is a linear amplification protocol, rather than an exponential amplification like PCR, some biases in amplification can occur. It is therefore prudent to treat all samples similarly when preparing targets for array hybridization. That is, either all or none of a set of samples should be amplified before labeling, to ensure consistent ratios among samples.