DGGE and Smiling bands! - Side bands on my DGGE gel keep smiling! (Jan/18/2005 )

Hi! we've just got some new DGGE apparatus for our lab and after several attempts at running gels of a 40-70% gradient we always seem to get really bad smiling of the side wells. We run it over night at about 66volts. Any ideas how we can stop the smiling?

Concentration salt in buffer?

Keep on smiling

Do you have the sides of the plate closed off with electrical tape while running the gel?