FIGURE 9.1 - Diagram of a test digest of high MW DNA. In this example, comparison of the eleven DNA HindIII reactions by gel electrophoresis indicates that the reaction conditions in tube "e" (0.375 units/ml, 20 minute digestion) provide optimal DNA fragments for BAC library construction. The reason for this conclusion is that of all the lanes, lane 7 (the lane in which the contents of tube "e" were placed) contains the largest percentage of fragments within the optimal insert size range of 100-350 kb (i.e., area enclosed by the dotted line). The conditions in tube "d" would also be suitable (and perhaps preferable to those interested in cloning the fragments > 150 kb).