Chromosome structures of trt1- survivors. (a) The 13 NotI restriction sites in S. pombe chromosomes I and II  are indicated by vertical lines. Chromosome III does not have a NotI site. Terminal fragments are labeled according to convention and highlighted in black. (b) Pulsed-field gel analysis of intact chromosomes visualized by staining with ethidium bromide. Lanes d-g correspond to days 1, 7, 9 and 15 of the growth curve, respectively. (c) Pulsed-field gel of NotI-digested chromosomes visualized with ethidium bromide. Days 1,7, 9 and 15 correspond to days of the growth curve. Lanes a and f were repositioned from the original gel image. (d) The gels from (c) were transferred to a nylon membrane and probed with a mixture of 32P-labeled probes to internal regions of the C, I, L and M fragments, identified in (a). The terminal fragments of linear chromosomes are labeled on the left, and fragments C+M and I+L resulting from circularized chromosomes are shown on the right.