Homozygotes displays defective puffing patterns, can be restored to wild type patterns by in vitro incubation in ecdysterone.
Dying larvae have melanotic pseudotumours.
When the salivary glands of homozygotes for dor22, an allele that causes death in the third larval instar with no signs of ecdysone induction, were incubated with ecdysterone, the development of puffs was restored (Biyasheva, Belyaeva, and Zhimulev, 1985).
Salivary gland chromosomes of homozygotes show no signs of developmental puffs. Incubation of mutant cells with ecdysterone restores developmental puff formation.