FIG 4.

Detection of furfural-induced chromosome breaks in a yeast strain with circular chromosome III. The haploid strain Yyy123 used in the experiment had a circular derivative of chromosome III and a LEU2 insertion on both chromosome III and chromosome II. (A) In an in vivo experiment, yeast cells were treated with furfural (0 to 2%) and prepared for CHEF gel (left) and Southern blot (right) analyses using a LEU2-specific probe described in Materials and Methods. (B) In an in vitro experiment, cell-free DNA prepared in plugs was treated with furfural and then examined by gel electrophoresis as for panel A. The calculated numbers of DSBs per genome are shown below the gel. “N” indicates that DSBs were not detectable.