FIG. 3.

Expression of native Ty1 elements in haploid and diploid cells. The figure shows the β-galactosidase activity of the TY1A-lacZ fusions that gave a blue or light-blue color in filter lift assays of diploid cells. The total is the sum of the specific activities obtained with the 31 TY1A-lacZ fusions expressed in haploid cells and in diploid cells. GAL1p-PR1 is a TY1A-lacZ fusion, in which the U3 region of 5′ LTR has been replaced by the GAL1 promoter at Ty1(PR1) (see Materials and Methods). +glu., in the presence of glucose; +gal., in the presence of galactose. FUS1-lacZ is carried on pSL974. Diploid cells were obtained by mating the FYBL1-23D derivatives carrying different TY1A-lacZ fusions with FY839.