Lamin B1 and Neural Tube Defects Figure 5. Nuclear morphology is influenced by Lamin B1 variation. (A) MEFs derived from embryos of various genotypes were stained with DAPI (blue) and antibodies to lamin B1 (green) and lamin A (red) to highlight the nuclear lamina. Abnormalities observed include lobulations (yellow arrowhead) and herniations (white arrowhead). (B, C) Analysis of MEF nuclei reveals significant differences between sub-strains in (B) mean contour ratio and (C) percentage of nuclei with contour ratio lower than 0.7, which is considered dysmorphic (p,0.001; ANOVA). (B) Mean contour ratio (expressed as mean 6 SEM) is significantly higher in C57BL/6 and significantly lower in ct than all other strains. (C) Compared with all other strains, ct has a significantly higher frequency of dysmorphic nuclei (47.465.8%) and C57BL/6 (15.163.9%) has significantly fewer dysmorphic nuclei (** significant difference from all other strains, p,0.01). The proportion of dysmorphic nuclei is lower in strains with the wild-type Lmnb19E allele, but higher than in C57BL/6; * indicates significantly different from all other strains (p,0.01 for comparison with C57Bl/6, ct and ctTgGrhl3 and p,0.05 for comparison with +ct or ct9E). Over-expression of Grhl3 partially normalises nuclear phenotype in the ctTgGrhl3 strain (despite presence of Lmnb18E variant as in ct). The mean contour ratio is significantly higher than in the ct strain but lower than in ct9E or +ct strains (** indicates significant difference compared with all other strains tested, p,0.01). Values are an average of 9–15 experiments, using 2–3 independent cell lines for each strain. Total number of cells analysed: 579 C57BL/6; 895 +ct; 757 ct; 882 ct9E; 837 ctTgGrhl3. doi:10.1371/journal.pgen.1003059.g005 PLOS Genetics | www.plosgenetics.org 8 November 2012 | Volume 8 | Issue 11 | e1003059