SUA5 deletion causes telomere shortening. (A) Telomere blot shows telomere shortening in early passages (within 165 generations after sporulation) of the MTR10, KAE1 and SUA5 deletion strains. The ‘1st' and ‘5th' indicate the first- and fifth-restreaked cells, respectively. The genomic DNA was digested with XhoI, and hybridized with a telomeric TG probe. (B) The sua5Δ cells were restreaked on YPD plate for 15 times (about 400 generations after sporulation), and the restreaked times are labelled on the top of the panel. The genomic DNA was digested with PstI. PstI and XhoI digestions (panel A) of the wild-type yeast genomic DNA result in approximately 0.8 and approximately 1.3 kb terminal telomere signals, respectively. PstI digestion reveals subtle telomere length changes. (C) A CEN plasmid-borne SUA5 progressively restores the telomere lengths in sua5Δ cells. The numbers indicate the restreaked times. (D) Telomere blot analysis of the genetic interactions of SUA5 and some well-characterized telomere maintenance genes. The isogenic strains are labelled on the top of the panel. The cells were restreaked on YPD plate for three times after sporulation.