Fig. 1: A mef2ca allelic series demonstrates a range of severity and variation.

a Schematic of mef2ca genomic structure. All mef2ca mutant alleles and regions encoding known functional domains are annotated. b Heterozygotes for each mef2ca allele were pairwise intercrossed, and six days post-fertilization (dpf) larvae were stained with Alcian Blue and Alizarin Red to label cartilage and bone, respectively. The individuals were then genotyped, and the viscerocranium was dissected, flat-mounted, and imaged. Two full-sibling individuals are shown for each genotype to illustrate among-individual variation. Within-individual variation can be observed by comparing the left and right sides of a given skeleton. The following craniofacial skeletal elements are indicated in a wild-type individual: opercle bone (op), branchiostegal ray (br), Meckel’s (Mc), ceratohyal (ch), symplectic (sy) cartilages, interhyal (ih) and jaw (jj) joints. The symplectic cartilage is outlined with a white dashed line in all individuals. Indicated phenotypes associated with mef2ca mutants include: ectopic bone (arrowheads), interhyal and jaw-joint fusions (^), dysmorphic ch (arrows), reduced Mc (double arrowhead), and a shortened sy (red arrows). Scale bar is 100 μm. c Schematic depicting how symplectic cartilage length was measured from 6 dpf larvae. d Symplectic cartilage length was measured from 6 dpf larvae homozygous for the indicated mef2ca allele, and the left symplectic length was added to the right symplectic length to get a total length for each animal. The p-values from a two-sided Dunnett T3 test are indicated (****≤0.0001). e Symplectic cartilage length on the left and right sides of 6 dpf zebrafish was measured to determine asymmetry or the absolute difference between left and right for fish homozygous for the indicated alleles. The p-values from a two-sided Dunnett T3 test are indicated (***≤0.001, wild type vs. b631 p = 0.0002, wild type vs. co3008 p = 0.0003, wild type vs. b1086 p = 0.0008). There is no significant difference in asymmetry between any of the mutant alleles. In box and whisker plots, the box covers the 25th to 75th quartiles, the line is at the median, and whiskers extend to the minimum and maximum values. The following n numbers represent biological replicates (individual animals) for (d) and (e): wild type 23, b631 28, co3008 30, b1086 34. Source data are provided as a Source Data file.