Shows abnormal sugar-induced proboscis extension reflex. Given sugar stimuli aperB flies extended their probosces, not straight forward (as does wild-type), but backward; when these mutants show a partial extension of their probosces, the direction of the extensions is normal. When aperB1 mutants were reared at low temperature (18oC or 20oC), over 90% of the flies were normal, whereas the high culture temperature (over 25oC) caused an abnormal PER; the temperature at which the proboscis extension reflex was tested did not affect the phenotype.
