Parasite-induced enhancement of hemolymph tyrosinase activity in a selected immune reactive strain of Drosophila melanogaster
Article first published online: 7 FEB 2005
Copyright © 1991 Wiley-Liss, Inc.
Archives of Insect Biochemistry and Physiology
Volume 18, Issue 3, pages 159–168, 1991
How to Cite
Nappi, A. J., Carton, Y. and Frey, F. (1991), Parasite-induced enhancement of hemolymph tyrosinase activity in a selected immune reactive strain of Drosophila melanogaster. Arch. Insect Biochem. Physiol., 18: 159–168. doi: 10.1002/arch.940180304
- Issue published online: 7 FEB 2005
- Article first published online: 7 FEB 2005
- Manuscript Accepted: 10 JUN 1991
- Manuscript Received: 4 JAN 1991
- monophenol oxidase;
- diphenol oxidase;
- insect immunity
Larval hemolymph tyrosinase activity in Drosophila melanogaster was detected with high performance liquid chromatography with electrochemical detection. The enzyme hydroxylated L-tyrosine, and oxidized the diphenol substrates L-dopa and dopamine. In larvae of a selected immune-reactive strain the rates of tyrosine hydroxylation, dopa oxidation, and dopamine oxidation were markedly increased during the early stages of melanotic encapsulation of the eggs of the parasitic wasp Leptopilina boulardi. Tyrosinase activity was not modified in parasitized larvae of a selected susceptible strain of D. melanogaster, in which hosts the parasitoids developed unmolested. During the same period of parasitization, the amount of free tyrosine in immune reactive larvae was approximately three times higher than in susceptible hosts. These data indicate that the tyrosinase system of the immune reactive strain is activated during parasitization, and this results in the synthesis of some precursors which ultimately produce a melanotic and sclerotic capsule around the eggs of the parasite. Based on known genetic information of the enzyme system in Drosophila, it appears that at least two genes may be involved in the activation process, one associated with the proenzyme for monophenol oxidase activity, and the second with the proenzyme for diphenol oxidase activity.