Hemizygous lethal. Heterozygotes have a neurogenic phenotype and have an increase in the number of thoracic bristles compared to wild-type. The number of bristles is restored almost to wild-type in NM1 ; Dp(1;2)51b double heterozygotes.
NM1 defines a new class of Notch allele. Hemizygous embryos die with severe neurogenic phenotype. Shows classic Notch phenotype when transheterozygous with fa and nd classes of alleles. Antimorphism revealed in males where the lethality is rescued by a duplication for Notch but the rescued males retain a wing vein thickening and notched wing phenotype. NM1 shows suppressive interactions with "NAx" alleles of both the enhancer of Notch and suppressor of Notch class, but lethal Abruptex class Notch alleles are lethal when heterozygous with NM1. Suppressive interactions also evident with alleles of the split class of Notch alleles.