Flies have a number of brain defects, the exact phenotype depending on the genetic background. In the original genetic background in which it was induced, cxb1 produces the following phenotype; the calyx has a variable size and shape, the peduncle is usually present but the lobes are absent, the ellipsoid body is open ventrally and the noduli are misshapen. When placed in a Canton S background by chromosome substitution, the cxb1 phenotype is altered, and the calyx, peduncle, ellipsoid body and noduli are less mutant than in the original genetic background and the lobes are usually absent. When placed in a Canton S background by recombination, the severe mushroom body and central complex revert towards wild-type after a few generations, and the calyx is often slightly misshapen.
Calyces are enlarged and have abnormal shape, pedunculi and lobes are small or missing, ellipsoid body is smaller.
Calyces of mushroom bodies in dorsal brain of adult are enlarged and have abnormal shape; peduncles and lobes (projecting from these calyces) small or missing; ellipsoid body of central brain also aberrant in morphology; learning abnormal, in tests using olfactory stimuli.
