Order of removal of the outron and the first intron in the rbcS transcript.

(A) Schematic map of the 5’ end of the rbcS gene (not to scale). Boxes and lines represent, respectively, the exons and the sequences spliced out from pre-mRNA (outron and introns). The exons are labelled inside the boxes. The intervening sequences are labelled above the map (outron and two adjacent introns). The relative positions of the splice leader (SL; indicated with a vertical arrow) and the primers used in this study (1–4) are pointed out below the captions of sequence regions. The positions of the RT-PCR products are indicated by horizontal arrows with their predicted sizes. In parentheses, the sizes of intron-less products are shown. If two products of different length were possible (1–4; SL-4), the length of the obtained one was marked with an asterisk. (B) RT-PCR products obtained with various primer sets used in this study. Total RNA was extracted, treated with DNase, reverse transcribed, amplified and electrophoresed through an agarose gel. All obtained products were further purified and sequenced to validate their origin. RT primers are listed in the upper row of the table, PCR primers corresponding to individual products are listed in the bottom row. Two agarose gels (corresponding to RT primers, respectively) were merged within the table. The first lane of each gel contains the DNA ladder GeneRuler 100 bp plus (Thermo Scientific), whilst the following lanes contain PCR products (one primer set per each lane) and corresponding negative controls (-RT reactions).