Isolation and transient activity of a krtt1c19e promoter.

Map of the genomic context of the krtt1c19e gene in the type I keratin cluster on chromosome 19 (A) with a schematic of the intron/exon structure of the krtt1c19e gene and the upstream cki gene (B). The entire sequence upstream of krtt1c19e to the end of the cki was isolated and cloned upstream of egfp (C). Injection of this krtt1c19e:egfp construct into embryos yielded limited epidermal expression at 24 hpf but widespread eGFP expression by 48 hpf (C). E–L: Micrographs of eGFP positive epidermal cells in both the basal layer (E–H) and EVL (I–L), demonstrated by co-immunofluorescent labelling with antibodies against eGFP (green – E–L), ΔNp63 (red – E–G, L), E-cadherin (red - H) and ZO-1 (purple – I-K). At 24 hpf (E, I), 48 hpf (F, J) and 72 hpf (G–H, K–L) both ΔNp63 and E-cadherin positive basal cells are eGFP positive as are ZO-1 positive EVL cells. eGFP positive EVL cells can be seen above ΔNp63 positive nuclei (arrowheads - L).