A UG to AC mutation has been introduced into both the upstream and downstream B boxes in the 3' UTR of bcd+t6.
The addition of bcdNRE1 to wild-type embryos interferes with head development in the larva. 98% of mutants fail to develop the normal mouth hook projection. 89% of mutants fail to complete head involution. These cuticles show a reduced head skeleton and the deformed labrum remains exposed to the exterior of the cuticle.