Genomic organization and alternative transcripts of nb054 / spinalin. (a) Mapping of spinalin and nb054 alternative transcripts to the corresponding genomic locus (H. magnipapillata genomic scaffold NW_002161446). The resulting gene-model shows two alternatively used stop codons indicated by asterisks. Since this genomic region is rich in AT repeats (n), some sequence areas remain unresolved and, therefore, the final number of nb054-specific exons remains to be determined. (b) Northern blot analysis with spinalin and nb054 specific probes (yellow lines in (a)).