1L TERRA acts in cis and leads to shortening of telomere 1L.

<p>(A) 1L TERRA expression leads to shortening of telomere 1L. <i>Upper panel:</i> DNA was extracted from five independent clones of the TetO7-1L strain grown at 30°C on YPD plates with (+) or without (−) Dox for 25 generations and analyzed by telomere PCR for telomere 1L on a 2.5% agarose gel. Marker (M) is given in bp. <i>Lower panel:</i> 1L telomere PCR products were TOPO cloned and sequenced. Shown is the average length of the TG-tract under inducing (−Dox) and non-inducing (+Dox) conditions with standard deviations. 10 sequences were analyzed for each condition. (B) Telomere 6R is not affected by expression of 1L TERRA. Telomere PCR for telomere 6R performed with DNA from (A). (C) 1L TERRA expression does not affect the average length of Y′ containing telomeres. DNA was extracted from the indicated strains grown as in (A) and digested with <i>Xho</i>I before Southern blot analysis. The Southern blot was hybridized with a 5′ end-radiolabeled CA oligonucleotide detecting telomeric TG repeats of yeast telomeres. The telomeric TG repeat signals are highlighted with a line (<i>Xho</i>I fragment). Marker (M) is given in bp.