All blood was collected in EDTA and stored at -20C for DNA analysis. Extracted DNA was dissolved in an appropriate amount of TE buffer. Each reaction mixture was overlaid with 50 mL mineral oil to prevent evaporation during thermocycling. Thermocycling was carried out on a Corbett Research FTS-320 Fast Thermal Sequencer. After each PCR was completed, the products were electrophoresed on a small agarose gel.
Surface tension keeps the agarose from running off the sides.
The plate and gel can then be placed into the buffer tank. 8 mL of PCR product was mixed with 1 mL of gel loading buffer and loaded into each well. A DNA molecular weight marker which contained pUC19 DNA digested with Hpa II was loaded in one lane. The acrylamide gels were then silver stained for four hours to overnight using the method of Neilan et al. In order to examine the extent of linkage disequilibrium within the DRD2 gene, analysis was begun on a second marker.