TELOMERE-ASSOCIATED CHROMOSOME BREAKAGE IN FISSION YEAST RESULTS IN VARIEGATED EXPRESSION OF ADJACENT GENES

The sequence requirements for in vivo telomere function in the fission yeast, Schizosaccharomyces pombe, have been investigated. A 258 bp tr act of previously characterized cloned fission yeast terminal repeats adjacent to 800 bp of telomere-associated sequences is sufficient to s eed new telomeres onto linearized ars-containing plasmids when introdu ced into cells. The resulting transformants contain unrearranged, acen tric, linear episomes. Cloned telomeres, with and without telomere-ass ociated sequences adjacent to the 258 bp terminal repeats, were utiliz ed to introduce chromosome breaks at specific sites in a non-essential minichromosome. Truncated minichromosome derivatives were recovered c ontaining the ura4 or ade6 gene adjacent to a newly formed telomere. T hese telomeres exert reversible position effects on the expression of the adjacent ural or ade6 genes.