Aberrant splicing of sycp2 mRNA in sycp2its/its testes.A: cDNA sequences of the exon 8–9 junction of sycp2. The sequences of one sycp2+/+ (WT) and three sycp2its/its (its-1 to its-3) cDNA clones are shown. Two of the three sycp2its/its cDNA clones had a 5-bp insertion (in yellow) containing a premature stop codon (in red letters) at the exon 8–9 junction. B: Genomic sequences of the intron 8-exon 9 junction of sycp2. Sequences from sycp2+/+ (WT) and sycp2its/its (its) testes are shown. The sycp2its allele harbors a T-to-A substitution (in red) upstream of exon 9. The its and wild-type (canonical) splicing sites are indicated with vertical arrows. C: Splicing at sycp2 exon 8-exon 9 was examined by RT-PCR. The target sites of the PCR primers are shown above. Template cDNA was prepared from sycp2+/+ (WT) and sycp2its/its (its) testes from three individual fish. The PCR products were examined on a 20% acrylamide gel. D: Mini-gene splicing assay in the wild-type genetic background. RT-PCR was performed with caudal fin cDNA from transgenic fish with either wild-type (WT E8-9) or its-type (its E8-9) sycp2 mini-genes (S3 Fig). Wild-type fish without mini-genes were used as controls (-). See S3 Fig for more clones and the results of control PCR with a primer pair specific to EGFP.
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