Figure 4.

Truncation of the 1.0- and 0.60-Mb homologs of chromosome 3. (A) A schematic showing the full-length chromosomes (drawn in red) and the truncated products (1-3) (drawn in black). Product 1 was derived from the 1.0-Mb homolog, and was generated by integration at the GPI locus. Products 2 and 3 were derived from the 0.60-Mb homolog, and were generated by integration at the GPI and UP1 loci, respectively. The 65-kb region encompassing the transcriptional strand-switch region (common to both homologs) has been expanded. The directions of polycistronic transcription are indicated by green arrows (for details, see also Fig. 5). (B) Chromosomal DNA from wild-type (WT) and transformed cells was analyzed by CHEFE (left panels, ethidium stained gels; other panels, autoradiographs of similar blots probed as indicated). (Lanes 1,2,3) The corresponding truncated chromosomes. (C) Blot of genomic DNA from cells containing the 0.36-Mb truncated product (as in lane 3, above) digested with ScaI. Comparison of telomere lengths (plasmid probe) in the initial clonal population and after 50 generations.