TALEN-induced irf8 mutations st95 and st96 eliminate embryonic microglia but allow survival to adulthood.
(A) TALE nucleases target region near irf8 translational start site, creating frameshift mutations st95 and st96, which introduced premature stop codons as shown (bottom). Top panels show representative neutral red staining for microglia in irf8st95/st95 mutant that lacks all microglia, compared with a heterozygous sibling that has a wildtype microglial population (arrow). (B) Analysis of apoe RNA expression by in situ hybridization shows presence of microglia in irf8 sibling but no microglia in irf8 mutants at 3 and 6 dpf. (C) Images of heterozygous and homozygous mutant larvae at 5 dpf, showing that the mutants have normal overall morphology. Images of the whole adult zebrafish were compiled from two tiled images of the same fish. At 3 months of age, the irf8 mutant zebrafish grew to a similar size as its sibling. All images represent the st95 allele. Scale bars are shown below each set of panels or for each individual panel.