Figure 9. GATA enhancer sequences control
dkf-2 gene promoter activity in intestinal cells in vivo. Transgenic C. elegans that express GFP-nuclear localization signal under control of the
dkf-2 gene promoter were created (Experimental Procedures and Results). A presents a representative Nomarski interference image of an L2 larva. An arrowhead points to the tip of the head. Reporter (GFP) expression was monitored by confocal fluorescence microscopy (
x600 magnification for embryos and
x63 magnification for larvae). B, fluorescence signals reveal
dkf-2 promoter activity in nuclei of intestinal cells. (Asterisks mark intestinal cell nuclei.) Note the outline of the sinuous intestinal lumen.
dkf-2 promoter activity is evident in two cells near the posterior pharynx (arrow). C is a composite image generated by overlapping A and B. Composite images show
dkf-2 promoter activity in the intestine of L1 (D) and embryonic (E) C. elegans. Reporter gene expression is also detected in pharyngeal cells in D and E (arrows). Deletion of GATA enhancer DNA sequences extinguished
dkf-2 promoter activity in intestinal cells (e.g. in L2 larva (F), embryos (G), and adult animals (not shown)). GFP reporter expression in pharynx was not altered by loss of GATA enhancers (arrows, F and G). H shows the nucleotide sequence of proximal, 5' promoter/enhancer DNA and codons 1 and 2 of the
dkf-2 gene. The initiator ATG codon is shown in italics and dashed underline; GATA enhancers are indicated with a solid underline; nucleotides deleted in the mutated promoter/enhancer DNA are marked with a bold font. The sequence is numbered according to the GenBank file (Z82052) for recombinant cosmid T25E12.