FIG. 1.
Structure of the recombination construct and insert locations. (A) DSBs on chromosome III. Breaks were mapped by pulsed-field gel electrophoresis of DNA prepared from MJL2305 just before (mitotic) or 6 h after (meiotic) transfer to sporulation medium. The probe used was a PCR fragment from the left end of chromosome III (nt 15838 to 16857). Positions of DSB regions I to V (3) are indicated above the autoradiogram; locations of the cold region URA3-arg4 inserts used in this study are indicated on the map of chromosome III below the autoradiogram. (B) Structure of inserts. Plasmids contain pBR322 sequences (thick line), a 1.2-kb HindIII URA3 fragment (hatched box), and a 3.3-kb PstI arg4 fragment (open box), containing either the arg4-nsp or arg4-bgl allele. Thin lines represent flanking genomic sequences used for integration, with × indicating the restriction site used for integration. Vertical arrows indicate the approximate location of DSBs seen in all inserts.