JPR Advance Access originally published online on August 24, 2006
Journal of Plankton Research 2006 28(11):1047-1053; doi:10.1093/plankt/fbl038
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Expression of serotonin and enkephalins in calanoid copepods (Crustacea): an immunohistochemical study
Equipe Biodiversité et Environnement, Laboratoire de Biologie Animale—Case 18, Université de Provence, 3, Place Victor Hugo, 13331 Marseille Cedex 3, France
* Corresponding Author: roxane.barthelemy{at}up.univ-mrs.fr
Received March 13, 2006; accepted in principle June 28, 2006; accepted for publication August 17, 2006; published online August 24, 2006
Communicating editor: R.P. Harris
Copepods are the main metazoan component of zooplankton, in terms of both the number of species and biomass. Thus, they have a key role in pelagic food webs; but curiously, nothing is known of the neuroendocrine substances involved in their physiological processes. In higher crustaceans, especially the Decapoda, the role of such molecules in different physiological processes (motility, feeding, reproduction, day-night migrations and so on) has been well explored; so, we have mapped expression sites of some of these substances to provide a better understanding of copepod physiology. Serotonin and, for the first time, leucine- and methionine-enkephalin were detected in copepods using immunofluorescence techniques. Serotonin has mainly been identified in the central nervous system acting probably as a neurotransmitter, notably in the control of the escape reflex. In contrast, enkephalins are only present in peripheral organs such as the naupliar eye, gut and shell glands. This localization suggests that opioids are involved in visual function and reproductive and digestive processes.
In memory of Professor Jacques Mazza, an eminent copepodologist.