Table 2.

ISNb and SNa phenotypes of plexin B LOF mutants

Distinct SNa defect
Genotype*Abnormal ISNb pathways (n) [bypass]Abnormal SNa pathways (n)dtstalllost
Wild type12.6% (294) [0]5.5% (293)1.0%4.4%0.0%
PlexBKG00878/+15.3% (157) [2.0%]25.9% (155)2.6%22.6%0.6%
PlexBKG00878/PlexBKG00878 55.3% (349) [16.0%]73.6% (341)33.1%25.8%14.7%
PlexBKG00878/Df(4)M101-62f 57.4% (129) [10.9%]76.9% (127)24.4%28.3%22.0%
UAS:PlexB, elav-GAL4/+; PlexBKG00878/PlexBKG00878 20.0% (115) [0.9%]36.3% (124)10.5%20.2%4.8%
UAS:HA-PlexA, elav-GAL4/+;; PlexBKG00878/PlexBKG00878 40.9%§ (215) [8.4%]74.2% (213)36.2%20.2%18.3%
PlexADf(4)C3/PlexADf(4)C3 65.7% (140) [10.7%]60.3% (136)3.7%50.0%4.4%
UAS:PlexB, elav-GAL4/+; PlexADf(4)C3/PlexADf(4)C3 81.2% (144) [23.6%]81.0% (137)2.2%71.5%7.3%
  • * Abnormal ISNb phenotype defined as the failure of ISNb axons from the RP5, V or RP3 neurons to properly innervate ventral longitudinal muscles 12/13 or 6/7. Phenotypes include weak or absent innervations, target bypasses and axon bundle stalling. The number of hemisegments scored for each genotype is listed as n. Bypass indicates the percentage of all segments in which the ISNb fails to fully or partially separate away from the ISN.

  • Abnormal SNa phenotype defined as the failure of SNa axons to defasciculate, to reach muscle 24 and/or to project along the appropriate route. The number of hemisegments scored for each genotype is listed as n.

  • `dt', `stall' and `lost' are distinct phenotypes that comprise the total SNa defects. dt (double turn) indicates the percentage of all hemisegments in which the dorsal SNa projects inappropriately between muscles 21 and 22 and ultimately reaches muscle 24. stall defines the population of SNa axons that are unable to reach muscle 24. lost represents the percentage of dorsal SNa projections that fail to reach muscle 24 after inappropriately projecting between muscles 21 and 22.

  • § Statistically different from values for PlexBKG00878 homozygous mutants. Fisher's exact test using a 2×2 contingency table; P<0.0005.

  • Statistically different from values for PlexBKG00878 homozygous mutants; P<0.01.