Haemocyanin Synthesis in the Crayfish, Astacus leptodactylus: in vitro Production by the Midgut Gland after Addition of Oxygen Binding Modulators and Exogenous Copper

The copper containing oxygen carrier haemo­ cyanin is the predominant protein in the hemolymph of most molluscs, crustaceans and spiders. Despite its abundance and the detailed knowledge on physiological aspects, relatively little informa­ tion exists on haemocyanin synthesis and its regu­ lation [1-4], In analogy to haemoglobin, where the addition of haeme influences the haemoglobin production [5], copper has been discussed as a lim­ iting factor for haemocyanin synthesis, although its role in haemocyanin biosynthesis is unclear till now [2], In a previous study we found a decrease in haemocyanin production by the midgut gland of the crayfish A. leptodactylus after three days of in­ cubation in a medium without copper [6], The question arose whether copper might be a rate lim­ iting factor for haemocyanin synthesis. Knowl­ edge of the concentrations o f copper in the midgut gland and its secretion into the medium during the in vitro incubation as well as an investigation of the influence of exogenous copper on haemocyanin synthesis and secretion should shed some light on the role of copper in haemocyanin biosynthesis. In recent years it has been shown that L-lactate, uric acid and dopamine can modulate oxygen binding of haemocyanin [7-9], but it is not known so far whether these modulators also exert an in­ fluence on haemocyanin synthesis. We therefore investigated this positive influence of the modula-