Cooperative effect of 1,2-propanediol and trehalose on amplification of difficult-to-amplify DNA templates. (A) DNA fragment of the human gene NP_001035158.1 (Fr. 7; 735 bp; 73.1% GC) was amplified from the whole blood (2% final) in PCR mix II supplemented with 0.2 M trehalose (T, final concentration), 1M 1,2-propanediol (P) or mixture of both (PT). Alternatively, PCR-amplified DNA (Fr. 7) was diluted in H2O and used as a template for PCRs performed under various conditions as above. PCR mixes supplemented with H2O instead of enhancers (line 4 and 8) and a mix without enhancers and template (line 9) served as controls. After amplification the fragments were analyzed by agarose gel electrophoresis and stained with ethidium bromide. (B) PCR amplified DNA (Fr. 7) was re-amplified and analyzed as in A, except that PCR mix II was supplemented with SGI (left) or vehicle (DMSO) alone (right). After amplification the fragments were analyzed by agarose gel electrophoresis and stained with ethidium bromide. Numbers to the left indicate migration of DNA ladder (L; in kbp). Gels from a typical experiment of at least four performed are shown.