Mutants exhibit additional fine branches emanating from the dorsal branches. Each additional sprout is derived from a tracheal cell located at the tip of the dorsal branch contacting the cells the form the fusion and terminal cell sprouts in the wild type embryos. The extra branching cells arise by a cell fate transformation of a nonbranching cell adjacent to the terminal and fusion cells of the dorsal branch into a sprouting cell.
hecaFus-6-50 is rescued by Scer\GAL4esg-p127/hecaUAS.cSa
hecaFus-6-50 is not rescued by Scer\GAL4esg-p127/hecaΔ1.UAS
Extra branching phenotype can be rescued by Scer\GAL4p127-mediated expression of hdcScer\UAS.cSa, but not by hdcΔ1.Scer\UAS.