Biochemical CuSO4 Toxicity in Drosophila melanogaster Depends on Sex and Developmental Stage of Exposure

Paula Tais Halmenschelager, João Batista Teixeira da Rocha

Copper is a transition metal that exists in different chemical forms (e.g., Cu2+,Cu+, and Cu0) and at high concentrations it is toxic. Here, we investigated the Cu2+-induced toxicity in Drosophila melanogaster, evaluating the survival, locomotion, and the activity of acetylcholinesterase (AChE) and glutathione S-transferase (GST) enzymes. Flies were exposed to Cu2+(0.1-1 mmol CuSO4/kg of diet or approximately 0.1-1 mM Cu2+) and allowed to mate during 24 h. GST and AChE enzymes were evaluated in the larvae and in the head and the body (thorax + abdomen) of the adult male and females flies. The total number of adult females (0.4-1 mM) and males (0.75 and 1 mM) was decreased by CuSO4. The climbing ability was hampered in flies exposed to 1 mM Cu2+. In larvae, Cu2+(0.4-1 mM) increased AChE activity (P < 0.002). In males' heads, 0.4 mM Cu2+ increased the AChE activity (P < 0.01). In adults' bodies, Cu2+inhibited the activity in both sexes, but with greater effectiveness in males (0.1 to 1 mM) than in females (1 mM). Regarding GST activity, 0.1 mM Cu2+increased, but 1 mM decrease GST in larvae. In the head of flies, Cu2+decreased the GST activity at intermediate (0.4 mM) and increased GST at the highest concentration (1 mM) in males. In the bodies, the effect of Cu2+was similar. In conclusion, Cu2+exposure in D. melanogaster disrupted locomotion and enzymatic parameters that can be related to changes in AChE and in the detoxifying GST enzyme.