The susceptibihty of RNA to degradation by exogenous and endogenous RNase activity following cell lysis has been well documented (1 ,2 ). Moreover RNA usually occurs complexed with protein from which it must be released. Precautions to be taken against exogenous RNase include the use of plastic gloves, autoclavmg solutions after adding 0.1% (v/v) diethyl pyrocarbonate (DEPC; except Trrs, which reacts), and baking glassware, spatulas, and so forth at 180°C overnight (3 ).
