Quantifying the Genotype to Phenotype Map in Developing Mice

Abstract

ObjectiveQuantify phenotypic variance of face shape within mice after ablation of the gene encoding the E3 ubiquitin ligase, nitric oxide synthase‐interacting protein (Nosip).MethodsMouse embryos from a nitric oxide synthase‐interacting protein (NOSIP) knock‐out model were collected at e12.5 via cesarean section (n=39). Two‐dimensional images were taken of the head, and DNA was collected from the limb bud for genotyping via PCR. Additionally, skulls were collected post‐natally (23 – 263 days of age (n=25)), and were scanned via microCT (55kV, 0.2 second integration time, 145uA). Anatomical landmarks were manually placed along the skull, creating three‐dimensional coordinates. Data were corrected for rotation and scaling differences through a Procrustes transformation using MorphoJ. Standard geometric morphometric analyses were subsequently performed, and data were compared using principal components analyses (PCA).ResultsAll wildtype (WT) embryos appeared to have normal phenotypes (n=8), but there was a large phenotypic variation in mutants (Fig. 1), ranging from normal (n=19) to severe forebrain malformations (n=7) or resorption (n=6). Adult HET mice (n=9) also showed phenotypic variation, including lateral malocclusion (n=1), opaque eyes (n=4), or no eyes present (n=1). After correcting for skull size, there was minimal variation within the WT adults, but there was specific separation between HETs with normal phenotypes and abnormal phenotypes. Animals were separated by PC1 (left‐side of snout width asymmetry; 24.5% of total variation) and PC2 (snout length; 16.3% of total variation) (Fig. 2). Along the PC1 axis, three HETs are clustered within the WTs; however, PC2 separates the two HETs with an abnormal phenotype (no eyes and lateral malocclusion), while the remaining HET within the WT cluster has a normal phenotype. Visualizing the same PCA relative to sex does not distinguish unique clusters, suggesting that phenotype is not related to sex.ConclusionsThis model presents a unique opportunity to understand and study phenotypic variation within a HET genotype, as well as when comparing HETs to WTs, producing variation in both embryos and adults. The malformations present in the HET embryos resembles a sonic‐hedgehog loss‐of‐function phenotype, so more work will be performed to determine the affected signaling pathways and cellular processes.Support or Funding InformationTravel support was given by the American Association of Anatomists. This project is supported by NIH funding (R01DE01823, R01DE01963,R01DE021708).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.