A 351-bp genomic deletion removing parts of exon 8, most of exon 9, and the entire intron 9, which corresponds to a 286-bp deletion in the norpA cDNA. The resulting protein is predicted to encode 436 N-terminal amino acids identical to the wild type protein, followed by a frame-shift, resulting in the substitution of 120 amino acids and a premature stop codon. The mutant protein would interrupt the catalytic domain and lack the C-terminal tail required for Gαq interaction and rhabdomere localization.
norpA39, Rh70 and norpA39, cry01 double-homozygous adults reared under 12h:12h white light:dark cycles exhibit a significant delay in resynchronizing to a 6h delay in 12h:12h white light:dark cycle compared to controls; these phenotypes are not enhanced by additional cry01 and Rh70 homozygosity, respectively.
Following a 6 hour delay in their light-dark cycle, cryb norpA39 flies show a longer delay in resynchronizing their evening activity peak (5-7 days) compared to cryb flies. The addition of Rh52 or Rh61 to this background extends the time required for resynchronization to beyond 7 days. The addition of both Rh52 and Rh61 to the cryb norpA39 background results in minimal (if any) tendency to resynchronize circadian behaviour.
Following a 6 hour advancement in their light-dark cycle, cryb norpA39 flies show a longer delay in resynchronizing their circadian behaviour (several days) compared to either single mutant. Introducing either Rh52 or Rh61 to this background interferes more strongly with resynchronization, while the quadruple cryb norpA39 Rh52 Rh61 mutant shows the strongest phenotype.
Expression of CDaseScer\UAS.cAa under the control of Scer\GAL4GMR.PF suppresses the retinal degeneration seen in norpA39 flies. One copy of lacek05305 suppresses the retinal degeneration seen in norpA39 flies.
Double mutants of cryb with norpA39, neither of which cause entrainment problems alone, exhibit entrainment problems in the initial LD regime. Only 50% of those that entrain to the initial LD cycle were able to synchronize to a new light regime that applies 16-lux blue light. At lower light intensities nearly all of the double mutants fail to entrain to the new LD cycles.