Selective breeding just for ectopic bone penetrance modifies the behavior of the mef2cab1086 mutant allele.
(A) Low-penetrance mef2ca heterozygous adults were intercrossed and offspring were grown to adulthood. Fin amputation and genotyping identified mef2ca homozygous adults, which were imaged alongside wild-type siblings. Scale bar: 1mm. (B) 6 dpf full-sibling individuals from a single high-penetrance family were stained with Alizarin Red (bone) and Alcian Blue (cartilage), then genotyped and mef2ca heterozygotes and homozygous wild types were scored for presence of all mef2ca-associated phenotypes. (C) 6 dpf Alizarin Red and Alcian Blue stained skeletons were dissected and flat mounted, lateral view. In these individuals, a shortened symplectic (sy) cartilage phenotype is evident in mef2ca heterozygotes from the high-penetrance strain and mef2ca homozygous mutants from the low-penetrance strain. Scale bar: 50 μm.