FIG. 3.
Overexpression Sir3N counteracts the effect of overexpression of Sir3C at telomeres. The strain UCC3107, which carries ADE2 adjacent to the VR telomere, was transformed with plasmids as indicated as well as a second control plasmid. The control plasmids are the backbone vectors without SIR gene inserts, namely, pAAH5 and p423ADH (see Materials and Methods). Plasmids with SIR3 gene inserts are pADH-SIR3N and pADH-SIR3C (pMG17). In each case, two independent transformants were streaked onto medium lacking histidine and leucine to ensure maintenance of the plasmids and with limiting adenine concentrations. The cells were allowed to grow for 3 to 5 days at 30°C, and the plates were stored at 4°C to enhance the pigmentation of the cells.