Loading and transfer control for Northern hybridization.

We report a simple and inexpensive method to quantitate loading and transfer of RNA and to examine RNA integrity for use with Northern hybridization. This technique involves quantitation by computer-assisted video densitometry of a negative photograph of 28S and 18S rRNA from ethidium bromide-stained RNA fixed to nylon membranes. This method eliminates the issue of variability of expression of "housekeeping" genes and the need for a second round of hybridization to quantitate control probes.