Fig. 3.

Zygotic expression of CRISPR/Cas9 components ensures 100% penetrance. a Genetic quantification of dominant effect by maternal loading of Cas9 protein. Genotypes, gender frequencies, and fertility of progeny flies generated by reciprocal crosses between homozygous dgRNAs and heterozygous Cas9 flies. Bars represent means ± SD for three/four independent groups of parental flies. Gender frequencies from crosses with heterozygous maternal Cas9 were compared with those from the corresponding crosses with heterozygous paternal Cas9. P > 0.01**, P > 0.001*** by a t test assuming unequal variance. Solid bars indicate inheritance of Cas9 as a gene, while striped bars indicate inheritance of + allele. b Combinations of genotypes and maternal/zygotic contributions in embryos, and their penetrance. c Accumulation of high levels of biallelic mosaicism (BM) throughout development leads to the loss of gene function at the organismic level and ensures complete penetrance of induced phenotypes: lethality (lethal biallelic mosaicism (LBM)), female masculinization, or male sterility. Complementation of gene function in some cells by uncleaved wt alleles, and resistance alleles generated by NHEJ, are not sufficient to rescue the induced phenotype at the organismic level and therefore 100% of trans-heterozygous progeny have the induced phenotypes. Boxes get smaller and more abundant as cells divide