Figure 2.—

The gypsy insulator improved the expression of reporter genes with different promoters. (A) Histochemical GUS staining indicated the promoter activity of Silent Information Regulator 2 (AtSIRT2) in transgenic lines lacking the gypsy insulators (pHGWFS7-SIRT2). The expression level varied among the lines tested, even after staining for 15 hr. Six lines are shown. (B) Histochemical GUS staining indicated the promoter activity of AtSIRT2 in transgenic lines including the gypsy insulators (pGYPSY-SIRT2). The staining pattern was less variable (staining for 3 hr). Six lines are shown. (C) Quantitative GUS assay of promoter activities of AtSIRT2, 35S cauliflower mosaic virus (CaMV), Pinform1 (PIN1; auxin efflux carrier), and Pinform2 (PIN2) in transgenic lines with (using vector pGYPSY) or without (using vector pHGWFS7) the gypsy insulators. The GUS activity was calculated as nanomoles of 4-methylumbelliferone per minute per milligram of protein. Each value was the mean of 15 single-copy transgenic lines. Error bars represent standard deviation.