Fig. 2: Construction of 972SD4 strains containing a single SH region of strain 972.

a Construction strategy of 972SD4 strains. Pale green boxes, SH regions adjacent to telomeres; black boxes, marker genes (his7⁺ or ura4⁺) that replaced SH regions²¹; orange boxes, rDNA repeats; and red boxes, centromeres. Strains 972 and SD5 were crossed, and meiosis and sporulation (spore formation) were induced. Progeny with single SH regions were obtained. b Schematic illustration of telomere-containing NotI restriction fragments (shown in gray). Fragments L, I, M, and C contain SH1L, SH1R, SH2L, and SH2R, respectively. The size of each fragment is shown underneath. c Schematic illustration of the positions of DNA fragments detected by probes for telomeres and TAS (TAS1–3). Shown are the distances from telomeres in pNSU70. d Analyses of the chromosome end structures in 972SD4 strains. NotI-digested chromosomal DNAs of three independent strains of each 972SD4 were analyzed by PFGE followed by Southern blotting using telomere, TAS, or SPBCPT2R1.03 ORF probes. EtBr, ethidium bromide staining of the gel after PFGE. Note that SH1R lacks part of the SH region homologous to SPBCPT2R1.03 according to PomBase. Consistently, 972SD4[1R+] strains did not show an SPBCPT2R1.03. signal (also see Fig. 5). These data were reproduced twice.