Extended Data Fig. 1: Related to Figure 1. Efficiency of Syt2 deletion in airway secretory cells.

Bronchial airways of Syt2^WT and Syt2^D/D mice were stained with antibodies to Syt2 and secondary antibodies conjugated to horseradish peroxidase (brown colour, see Methods). Secretory cells in Syt2 WT mice (left panel) have a domed appearance with their apical poles staining intensely for Syt2 (filled triangle). There was less intense linear staining of tufted ciliated cells in the region of ciliary basal bodies (open triangle), which often stain non-specifically. Secretory cells in Syt2^D/D mice did not stain for Syt2 (filled triangle), but linear staining of ciliated cells was similar to that in Syt2^WT. We enumerated secretory cells in 3 mice of each genotype and found 46% in Syt2^WT and 48% in Syt2^D/D, ±4%, which did not differ significantly, indicating there was no loss of viability of secretory cells in Syt2^D/D mice. In Syt2^WT mice, 91% of secretory cells stained for Syt2, whereas in Syt2^D/D mice, only 7% stained for Syt2, indicating a deletion efficiency ~92%. Results for Syt2^F/F mice were indistinguishable from those for Syt2^WT. Scale bar, 50 µm. Experiments were repeated twice with similar results.