RT-PCR analysis of 5 S expression. (A) Schematic representation of a part of the 35 S-5 S unit. The 5 S rDNA1 is present in all species; additional 5 S rDNA2 is found in some A. absinthium units . (B) Schematic representation of minor 5 S-5 S tandems in A. tridentata. Positions of primers are indicated by arrowheads. The arrowed lines below indicate putative transcripts primed from the Pol III promoters analyzed in (C-E). Black – coding region transcripts. Gray – long transcripts containing variable portions of IGS sequences. Cycling conditions: (C) – 29 cycles; (D-E) – 35 cycles. “+RT” and “-RT” indicate reactions with or without a reverse transcription step.