I've been running some massive DNA-agarose gels in a screening application downstream of PCR. The gels contain 4 combs of 50 lanes each. The center of the lanes within a comb are separated by about 5mm. I cut the gel prior to imaging, so that only 50 lanes are imaged at a time.
I think I'm running into some problems with these large gels in relation to the UV signal. I think I might not be detecting weak (low concentration) DNA bands on these gels. Can bright DNA bands in adjacent lanes 'mask' weak DNA bands lanes? The camera needs to be zoomed-out pretty far to encompass all of the lanes, and I think I might be losing sensitivity? I noticed if I crank up the exposure, weaker bands do appear, but the other, stronger bands, become oversaturated as does my DNA ladder.
I could load more of these weaker samples, but the issue is I will not know which lanes need to have more loaded until after I run the first gel. It would be ideal to only have to run the gel once, as this is a screening process and quite laborious.
Thanks for any help!