Fig. 2. The transposon insertion specifically affects YIL090w expression. (A) Mapping of the transposon insertion site in TMT561. Insertion of the Tn3 transposon in TMT561 (strain SFNY1052) maps between the ORFs YIL091c and YIL090w on chromosome IX. (B) The Tn3 transposon specifically affects expression of YIL090w. RT-PCR was performed on samples prepared from the wild type (lanes 2-4) and from TMT561 (lanes 5-7). Primers for YIL090w (lanes 2, 5) and YIL091c (lanes 3, 6) were used to determine whether the message levels in either ORF were affected by the Tn3 transposon. Primers for AUX1/SWA2 were used as a positive control (lanes 4, 7). (C) RT-PCR was performed on RNA samples prepared from wild type (lanes 2-5, 7) and TMT561 (lanes 6, 8). Primers for YIL090w (lanes 2-6) were used to determine message levels at increasing concentrations of RNA. Primers for AUX1/SWA2 were used as a positive control (lanes 7, 8). Lane 1 in B and C contain the molecular weight standards.