Abstract
Drosophila melanogaster Meigen mutants for N-β-alanyldopamine (NBAD) metabolism have altered levels of NBAD, dopamine and other neurotransmitters. The ebony[1] mutant strain has very low levels of NBAD and higher levels of dopamine, whereas the opposite situation is observed in the tan[1] mutant. Dopamine is implicated in the control of movement, memory and arousal, as well as in the regulation of sleep and wakefulness in D. melanogaster. N-β-alanyldopamine, which is best known as a cuticle cross-linking agent, is also present in nervous tissue and has been proposed to promote locomotor activity in this fly. The daily locomotor activity and the sleep patterns of ebony[1] and tan[1] mutants are analyzed, and are compared with wild-type flies. The tan[1] mutant shows reduced locomotor activity, whereas ebony[1] shows higher levels of activity than wild-type flies, suggesting that NBAD does not promote locomotor activity. Both mutants spend less time asleep than wild-type flies during night-time; ebony shows more consolidated activity during night-time and increased sleep latency, whereas tan is unable to consolidate locomotor activity and sleep in either phase of the day. The daily level of NBAD-synthase activity is measured in vitro using wild-type and tan[1] protein extracts, and the lowest NBAD synthesis is observed at the time of higher locomotor activity. The abnormalities in several parameters of the waking/sleep cycle indicate some dysfunction in the processes that regulates these behaviours in both mutants.
