Fig. 3

Endoxifen confers CreERT2 mediated recombination at a lower potency in tissue specific lineage tracing experiment. (A-C) Transverse vibratome sections of ubi:creERT2;ubi:Switch at 4 dpf were performed to control for tissue bias in trans-4-OHT- versus Endoxifen-induced recombination. (A) Sections of posterior trunk (trans-4-OHT n = 13; Endoxifen n = 10), (B) anterior liver (l) and gut (g) (trans-4-OHT n = 7; Endoxifen n = 3), and (C) telencephalon (trans 4-OHT n = 7; Endoxifen n = 3) show similar switching efficiencies among tissue sections between the two compound treatments. Representative images are shown for each condition. Merged: EGFP, mCherry, and DAPI. (D) To compare trans-4-OHT and Endoxifen potency in a tissue-specific lineage tracing experiment, drl:creERT2 transgenics were crossed to ubi:Switch. (D, E) trans-4-OHT induced CreERT2 mediated recombination more potently at saturated concentrations (10 µM) and non-saturated conditions (0.1 µM) compared to Endoxifen. For quantifications shown in D, switched intersomitic vessels (ISV) in trans-4-OHT or Endoxifen treated drl:creERT2;ubi:Switch were imaged with the Zeiss lightsheet Z.1 and counted in the maximum intensity projection (scale bars 200 µm). In embryos treated with 10 µM trans-4-OHT, all ISVs in the analyzed part of the trunk are mCherry positive with very few parts of individual ISVs unlabeled. Reducing the concentration to 0.1 µM confers sub-optimal switching for clonal analysis. Endoxifen shows lower potency with fewer mCherry positive ISVs. Lowering Endoxifen concentration to 0.1 µM fails to induce efficient CreERT2 activation.