FIG. 4.

Southern blot analyses of a defined telomeric fragment from P. tetraurelia transformants. Digestion of the pPXVII-TER series of linearized, microinjected plasmids with SacI generates a telomeric fragment of approximately 1.2 kb that includes the telomerase RNA gene (arrow; see Fig. 2). Southern blots of total DNA (1 μg) from transformants digested with SacI and probed with the radiolabeled P. tetraurelia telomerase RNA gene are shown. uninj., DNA from uninjected cells; PXVII, DNA from clones coinjected with pPXVII (without TER) and pPXV-NEO. All other samples were from clones coinjected with pPXV-NEO and pPXVII-TER, with the telomerase RNA substitutions as indicated. w.t., wild type.