Expression of 2A-Cre integration alleles recapitulates ascl1b, olig2, and neurod1 expression pattern. Whole mount in situ hybridization for endogenous genes and Cre was performed in 3 dpf larvae obtained from outcrossing ascl1b-2A-Cre/+, olig2-2A-Cre/+, and neurod1-2A-Cre/+ lines to wild type WIK. Sibling larvae from the same clutch were sorted into lens EGFP-positive and -negative groups before fixation. For each genotype and probe 3 individual larvae were photographed. (a–d) ascl1b and Cre expression in ascl1b-2A-Cre/+ larvae show similar patterns in the forebrain, and along the midbrain ventricle and midbrain-hindbrain border. (e–g) olig2 and Cre expression in olig2-2A-Cre/+ larvae were restricted to the forebrain, the posterior half of the cerebellum, and a subset of cells in the retina. (i–k) neurod1 and Cre expression in neurod1-2A-Cre/+ larvae were detected in the forebrain, adjacent to the midbrain and hindbrain ventricles and enriched in the cerebellum ((i′), C black arrow), and in the retina inner (large bracket) and outer (small bracket) nuclear layers (j). neurod1 and Cre expression were not detected in the posterior peripheral midbrain layer ((i′), PML white arrow). Cre expression was not detected in wild type +/+ sibling larvae (d,h,l). c cerebellum, fb forebrain, hb hindbrain, mb midbrain, mhb midbrain-hindbrain border, nt neural tube, ot optic tectum, pml peripheral midbrain layer, r retina. Scale bar 250 μm.
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