Electrophysiological characteristics of a population of mushroom body neurons in Apis Mellifera honeybees in kynurenine deficiency.

Electrophysiological methods were used to study the neurophysiological characteristics of mushroom body neurons in snow (laranja) mutant and wild-type bees. The snow (laranja) mutation, which produces a sharp reduction in the activity of the enzyme tryptophan oxygenase, thus creating a deficiency of all kynurenines in the body, modifies the bioelectrical properties of mushroom body neurons. The parameters most dependent on the snow (laranja) mutation and, thus, the level of endogenous kynurenines, were the duration of action potential afterdepolarization recorded from neurons in the calyx and the amplitude of the postsynaptic potential of neurons in the calyx evoked by focal stimulation of the antennal lobes. There was also a tendency to an increase in the spontaneous spike frequency. These data lead to the conclusion that the effect of the mutation is recessive in nature and appears only in homozygotes (bearing two mutant alleles).