HPLC analysis of lobster haemolymph over the molt cycle

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1. Haemolymph from various stages of the molt cycle of Homarus americanus were assayed for serotonin, octopamine and related substances by high performance liquid chromatography with serial UV and electrochemical detection. 2. 5-Hydroxyindole acetic acid (HIAA), 5-hydroxytryptophan (HTP), tryptophan (TRP), serotonin (5HT), octopamine (OA) and four unidentified compounds were found. 3. Tryptophan and one of the unknowns (Compound S) varied significantly over the cycle; another unknown (Compound E) was absent in premolt stages, D2 and D3. 4. Comparison of blood from the same lobsters at two different molt stages revealed that there was significantly more TRP and compound S in premolt than in post-molt stages and more OA in intermolt than in premolt stages. 5. A comparison of female and male lobsters revealed significantly more OA, 5HT, TRP and compound S in males than in females. 6. The relatively constant levels of HIAA and the significant differences of TRP suggests differential turnover of TRP into 5HT over the cycle; this would support the idea that such differences contribute to molt-related differences in behavior. © 1989.

Publication Title

Comparative Biochemistry and Physiology. Part C, Comparative