Fig. 3. The jef^hi1134 mutation results from a retroviral insertion into sox9a and inhibits the formation of mature message. (A) Primers relative to genomic structure of sox9a. (B) A virus inserted into exon 2 in codon Leu 147, two base pairs downstream of the intron/exon border in Arg146. 5'LTR indicates the position of a primer. (C) Amplification products of mapping primers (see part A). (D) Primers F and R amplified a band of 627 bp from wild-type (WT) embryos, but a 376 bp band from homozygous jef^hi1134 embryos, showing that exon 2 (251 bp) was skipped in the splicing in jef^hi1134 mutants.