Fig 6.

Size and stability of VAC–BAC DNA. (A) DNA of VAC (WR), ts21–loxP–GFP–BAC (R) and numbered VAC–BACs were analyzed by pulsed-field gel electrophoresis. Similar bands (arrow) of approximately 200,000 bp were detected by ethidium bromide staining. Only a segment of the gel is shown. (B) The same DNA samples were digested with HindIII and analyzed by agarose gel electrophoresis. Note that the BC fragments of the VAC–BACs migrate with the A fragment. In addition, the J-size fragment of WR (lower arrow) is missing in ts21–loxP–GFP–BAC and all of the VAC–BACS because of inserted DNA. In VAC–BACs 5, 13, 34, and 51, the positions of the more slowly migrating J fragment containing BAC sequences is shown by the upper arrow. In ts21–loxP–GFP–BAC and VAC–BAC 22, the J fragment also contains the GFP gene, and therefore migrates more slowly and coincides with the next higher band.