Fig. 6. The telomere-lengthening phenotype of clk-2(qm37) mutants. (A-C) In C. elegans, genomic DNA hybridization to telomeric probes after restriction digestion with HinfI reveals smears that correspond to the terminal fragments of the chromosomes containing the telomeres, and discrete bands that correspond to fragments containing internal tracts of telomeric repeats (see text). (D,E) Hybridization with telomere-specific probes reveals a smear. For XL, discrete bands at 1.6, 1.9, and 2.4 kb are also detected by the subtelomeric probe and correspond to internal genomic fragments containing non-telomeric repetitive DNA located on other chromosomes that cross-hybridize with the probe. Worms were grown at 20°C (A,B) and at 25°C (C-E). Each panel represents an independent experiment (distinct worm cultures, DNA extractions and enzymatic digestions). MQ691 is a strain carrying a clk-2(+) transgene in a clk-2(qm37) background. MQ931 was derived from MQ691 by loss of the extrachromosomal array, and thus lacks clk-2(+). The sizes indicated are in kb.