Fig. 1. (A) Splicing pattern of nematode fibulin-1C and fibulin-1D. Exons are numbered as in Barth et al. (Barth et al., 1998) with the exception of exons 5 and X, which are labeled 5C and 5D, respectively. Horizontal line indicates region deleted in fbl-1(hd43). Arrows indicate region where GFP or YFP tags were introduced in the fibulin coding sequence. Arrowheads indicate region where mutations were introduced to inactivate specific splice variants (see materials and methods for details). (B) RT-PCR experiment demonstrating that exon 5C is detected in the fibulin-1C variant only, and is replaced by exon 5D in the fibulin-1D variant. Forward and reverse exon specific primers are listed respectively. Lane 1, exons 5C and 14; lane 2, exons 5C and 16; lane 3, exons 5D and 14; lane 4, exons 5D and 16.