ABSTRACT
The establishment of the yeast transformation system opened up the possibility to test if Tetrahymena ends could stabilize a linear duplex DNA in another eukaryote. Telomere length varies clonally within a population of yeast cells, and the length heterogeneity increases in parallel with the number of generations. A very limited drop in transformation efficiency was observed even when the gaps were made in plasmid sequences having no homology with the yeast genome. Marker genes used for Saccharomyces cerevisiae transformation are generally biosynthetic genes which complement the corresponding auxotrophy in the recipient. Autonomously Replicating Sequences-containing plasmids have been identified by their high transformation frequency and their instability in transformed cells of Saccharomyces cerevisiae, Schizosaccharomyces pombe, and Rhodosporidium toruloides.
