The increase in the number of tracheal branches that terminate on ventrolateral body wall muscle 12 caused by expression of agoΔF.Scer\UAS under the control of Scer\GAL4tey-5053A is suppressed if the flies are also heterozygous for bnl00857.
Pak6; bnl00857 double heterozygotes have a range of tracheal phenotypes not seen in single heterozygotes for either of these alleles: The mildest phenotype is a misrouting of the dorsal branches toward the anteroposterior direction; more severely effected embryos also exhibit truncations of the dorsal trunk.
Expression of Cdc42V12.Scer\UAS under the control of Scer\GAL4btl.PS in a bnl00857 background show occasional (4.4%) fusions of the adjacent lollipop-like dorsal trunk structures (bnl00857 single mutants show no fusion of the adjacent metameric tracheal units).
stumps09904b, bnl00857 double heterozygotes show a dramatic increase in tracheal outgrowth defects, with nearly four times as many stalled ganglionic branches as the bnl00857 heterozygote alone. The double heterozygotes also displayed increased dorsal branch outgrowth defects compared to bnl00857 heterozygotes as well as rare dorsal trunk outgrowth defects never seen in bnl00857 heterozygotes.
btlLG18 bnl00857 double mutants exhibit a tracheal phenotype similar to either mutant alone. btlLG19/btl+ bnl00857/bnl+ double heterozygote exhibits enhanced bnl00857 phenotype, defects in tracheal outgrowth. A constitutively activated form of the btl receptor (btl::tort4021b.hs.sev) can partially ameliorate the effect of absence of bnl; modest restoration of branching in bnl00857 embryos.