RT-PCR amplification of characteristic fragments of the different splice variants. The investigated sample genes with alternative splicing were clpr2 (A), efg8 (B), hyd2 (C), lsg2 (D), mgmt (E), nrnp1 (F), selEFf (G), cyn23 (H), oee1 (I) and ppi1 (J). Primers were designed to amplify a characteristic fragment of each alternative splicing variant specifically (Figure 4 and Additional file 1: Table S3). The amplicons of the first (V1) and second (V2) alternative splicing variants have been cloned and sequenced. The expected lengths of fragments are given in Additional file 1: Table S3. DNA fragments that are consistent with the predictions are marked by arrowheads.