Normal electroretinogram.

Phenotype of heterozygotes is similar to that of Hk¹ heterozygotes: ether-dependent leg shaking and wing scissoring. Flight ability is reduced and they show an impaired jump response. Homozygous flies are flightless and show greater agitation upon etherization. DLM, DVM and TDT muscles are swollen.

Flies heterozygous for Flu¹, have reduced flight ability, impaired jump response and relatively slight disturbances in morphology of Z bands and myofibrils of indirect flight muscles; these Flu/+ flies are also like Hyperkinetic (Hk) mutants in terms of agitated behavior after etherization; Flu¹/Flu¹ flies are more severely affected with respect to flight and Hk-like phenotype; Flu¹ studied for indirect flight muscle proteins and has reduced amounts of at least two high-molecular-weight materials.