A linear shuttle vector for yeast and the hypotrichous ciliate Stylonychia.

A linear plasmid was constructed in vitro using the telomeres of the rDNA of Tetrahymena pyriformis. These telomeres were added to a yeast circular vector containing an ARS sequence from Dictyostelium, the LEU2 gene of yeast and the neo gene from Escherichia coli Tn5 fused with a eukaryotic promoter. The resulting plasmid was used to transform yeast. During the replication of the linear plasmid in yeast it was spontaneously modified at the extremity by the addition of 300 bp of yeast telomeric sequence for each end. Total DNA prepared from yeast transformants was used to transform the hypotrichous ciliate Stylonychia lemnae. The same plasmid isolated from Stylonychia can again be replicated in yeast.