Transposable Elements (Ty) in Yeast

Recent studies on the organization of chromosomal DNA in eukaryotes demonstrate that the eukaryotic genome contains families of dispersed repetitive DNA sequences (Finnegan et al. 1978; Cameron et al. 1979). These repeated sequences are several kilobase pairs (kbp) in length and differ widely in copy number and position among different strains of the same species. Analysis of chromosomal sequences, before and after insertion of an element, shows that these repetitive sequences move to new locations in the genome by non-homologous recombination events. The eukaryotic transposons can catalyze a large number of genomic rearrangements, including translocations, deletions, inversions, and transpositions (McClintock 1957; Chaleff and Fink 1980; Roeder and Fink 1980). The mobility of transposable elements contrasts sharply with the relatively invariant karyotypes and positions of structural genes among different strains of the same species. The function of transposable elements is unclear. The existence of viable organisms that lack families of these...