Drosophila melanogaster mutant for the dopamine recycling pathway shows altered biological parameters and increased lifespan

Abstract

The ebony and tan genes in Drosophila melanogaster Meigen (Diptera: Drosophilidae) participate in a very peculiar (and exclusive to insects) recycling pathway of neurotransmitters, mainly dopamine (DA) and histamine, in the nervous system and regulate the intensity of tanning in the cuticle. The ebony and tan mutants show altered levels of neurotransmitters, which give rise to developmental and behavioral impairments. The mutant tan lacks N-β-alanyldopamine hydrolase (NBAD-hydrolase) activity; therefore it is unable to liberate DA from NBAD. Here, we studied developmental traits in tan1 mutant and previously unknown biological parameters in adult males, such as oxygen consumption, antioxidant capacity, lifespan, and the expression of detoxifying enzymes in the central nervous system. We compared them with those of wt Canton S and the mutant ebony1. Our results show that although tan1 mutant had high mortality during the immature stages, adult males had a significantly longer lifespan than wt and ebony1 mutant; the latter had the shortest lifespan. The longer lifespan of tan1 was not due to caloric restriction. We found that the nervous system of tan1 males had a higher antioxidant capacity. After provoking mild oxidative stress by the ingestion of hematoporphyrin, tan1 males still had a significantly longer lifespan than wt, whereas the ebony1 mutant had a shorter one. Under these conditions, tan1 showed an increased expression of catalase mRNA. Our results suggest that lower levels of free DA in the nervous system together with higher antioxidant activities seem to favor an extended lifespan in D. melanogaster tan1 males.