Fig. 1. Generation and use of a knock-in reporter to trace npas4l-expressing cells in wild-type and mutant embryos. (A) An npas4l-p2a-Gal4-VP16 allele (bns313) was generated by knock-in at the 3′ end of the npas4l coding sequence. Subsequently, a knockout derivative of this allele, one lacking Npas4l function, was generated by mutating the DNA binding domain–encoding region. (B and B′) Use of a Tg(UAS:GFP) background to reveal the lack of intersomitic vessels (ISVs) in npas4l bns423 mutants; (B) shows an npas4l+/+ embryo from an intercross of npas4lbns313 hets, and (B′) shows an npas4l−/− embryo from an intercross of npas4lbns423 hets. (C and C′) npas4l reporter expression in the vasculature of npas4l+/− (left) and npas4l−/− (right) embryos. npas4l reporter expression marks endothelial cells in npas4l heterozygous embryos but skeletal muscle (M) and a ventral row of round cells in npas4l mutants (arrowheads). DA, dorsal aorta; PCV, posterior cardinal vein. Scale bars, 200 μm (B) and 50 μm (C).
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