COMPARISON OF MILLI-Q(R) PF PLUS WATER TO DEPC-TREATED WATER IN THE PREPARATION AND ANALYSIS OF RNA

The Milli-Q(R) PF plus water-polishing system is equipped with high-pu rity ion and organic removal media and a capillary fiber ultrafiltrati on device. The system produces ultrapure water practically free of rib onuclease contamination. The necessity for diethyl pyrocarbonate (DEPC )-treated solutions in RNA molecular biological procedures was tested by preparing RNA from a variety of tissues and tissue-cultured cells u sing either DEPC-treated, autoclaved solutions or pure Milli-Q PF wate r dispensed directly from the system. Tissue sources included rabbit b rain, heart, lung, liver kidney and bladder as well as cultured human corpus cavernosum smooth muscle cells. RNA was prepared by guanidinium isothiocyanate solubilization, phenol/chloroform extraction and isopr opanol precipitation followed by Northern blot analysis. Hybridization with fibronectin (ca. 7.6 kb) and glyceraldehyde-3-phosphate dehydrog enase (1.2 kb) revealed that water from a Milli-Q PF water system perf ormed as at ell as DEPC-treated, autoclaved solutions. RNA stability a t 37 degrees C was examined for various times using rabbit lung RNA in either DEPC-treated water or Milli-Q PF water Intact RNA was detected after 6 hours in total RNA and by Northern blots hybridized with fibr onectin. There was no significant difference in RNA degradation betwee n DEPC-treated water and Milli-Q PF water We conclude that Milli-Q PF water is an acceptable substitute for DEPC-treated water for the prepa ration of RNA and Northern blot analysis.