FIG. 1.

PCR in the presence of various concentrations of betaine. Lanes 1 and 5, no betaine (0 M); lanes 2 and 6, 0.5 M betaine; lanes 3 and 7, 1 M betaine; lanes 4 and 8, 1.5 M betaine. The two triangles indicate that the concentration of betaine increased from lanes 1 to 4 and from lanes 5 to 8. Lanes 1 to 4, PCR with primers gGS4 and gGAS4; lanes 5 to 8, PCR with primers gGS5 and gGAS5. The positions of the 194- and 234-bp fragments of HaeIII-digested φX174 replicative-form DNA are indicated to the left of the panel. The product obtained with gGS4-gGAS4 was 209 bp; that obtained with gGS5-gGAS5 was 191 bp.