A RAPID METHOD TO MONITOR DNA PRECIPITATION ONTO MICROCARRIERS BEFOREPARTICLE BOMBARDMENT

The binding or precipitation of DNA onto gold or tungsten microcarrier s represents one of the most crucial steps for gene transfer via the p article bombardment process. We have developed a simple and rapid meth od to monitor DNA precipitation onto microcarriers before delivery to intact cells or tissues. Binding of DNA constructs to different microc arriers was evaluated with relative fluorescence values using a dedica ted fluorometer. Significantly greater precipitation was detected usin g gold vs. tungsten microcarriers. Addition of glycerol resulted in a 46% increase in precipitation. A 42% difference in precipitation was o bserved using two different brands of polyproplyene tubes. Fluorescenc e values dropped 10-50% 3 hr after initial precipitation. Fluorescence values were correlated with the number of transient GUS transformants of rice (Oryza sativa, L.) cells. Precipitation with PEG gave higher fluorescent values and GUS transformants than a similar method without PEG. Results from these experiments indicate that fluorescence measur ements are an effective and rapid method to monitor DNA precipitation for particle bombardment experiments.