Fig. 6. Positional cloning of HST. The top line indicates the genetic map of the region surrounding hst-1, as determined from an analysis of F₂ progeny from a cross to Ler. The number of recombinants in each interval is indicated below the line. BACs that hybridized to the lamba clone m262, which showed no recombination with hst-1, are shown below this line. Hybridization of F9J1 to an EcoRV digest of genomic DNA from hst-9 and Col revealed a missing fragment in hst-9. When this EcoRV fragment was gel purified from F9L1 DNA and used to re-probe the blot, it hybridized to two fragments in hst-9. These fragments are not visible in the blot hybridized with the entire BAC because this blot was under-exposed in order to visualize as many fragments as possible.