FIG. 3.

Calculated sizes of fragments of BAC20 and mutant BAC genomes after HindIII digestion (A) and digitally scanned images of Southern blots to analyze size variations in the various mutants (B). DNA from BAC20, 20ΔgE, 20ΔgI, or 20ΔgEI was cleaved with HindIII and transferred to nylon membranes. Sheets were incubated with digoxigenin-labeled kanamycin resistance gene-specific, gE, or gI probes. The 1-kb ladder (Gibco-BRL) was used as a size standard. Fragments that are altered in the mutant BAC genomes when compared to the BAC20 genome (5.0, 6.6, 19.4, and 20.6 kbp) are indicated (arrowheads); the 26.0-kbp fragment of BAC20 containing the gE and gI ORFs is marked with an asterisk.