title: The pineal complex of the European sea bass (Dicentrarchus labrax): I. histological, immunohistochemical and qPCR study.
abstract: The pineal organ of fish is a photosensory and neuroendocrine epithalamic structure that plays a key role in the temporal organisation of physiological and behavioural processes. In this study performed in the European sea bass, Dicentrarchus labrax, we provided an in-depth description of the macroscopic and microscopic anatomy of the pineal organ and identified the presence of photoreceptor and presumed melatonin-producing cells using histological and immunohistochemical techniques. In addition, we analysed in the pineal the day-night expression (using quantitative real-time PCR) of two key enzymes in the melatonin-synthesising pathway; arylalkylamine-N-acetyltransferase 2 (AANAT2) and hydroxyindole-O-methyltransferase (HIOMT). The pineal complex of sea bass consisted of a narrow and short pineal stalk that adopts a vertical disposition, a small-sized pineal end vesicle firmly attached to the skull by connective tissue, a parapineal organ and a convoluted dorsal sac. Immunohistochemical study showed the presence of abundant serotonin-positive cells. Cone opsin-like and rod opsin-like photoreceptor cells were also evidenced in the pineal stalk and vesicle. Both Aanat2 and Hiomt were expressed in sea bass pineal organ. Aanat2 exhibited higher nocturnal transcript levels, while no significant day-night differences were found for Hiomt. These results, together with ongoing studies analysing neural and neurohormonal outputs from the pineal organ of sea bass, provide the basic framework to understand the transduction integration of light stimulus in this relevant species for marine aquaculture.
authors.affiliation: Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, E-11510 Puerto Real, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Herrera-Pérez
authors.forename: A
authors.initials: A
authors.lastname: Servili
authors.forename: M C
authors.initials: MC
authors.lastname: Rendón
authors.forename: F J
authors.initials: FJ
authors.lastname: Sánchez-Vázquez
authors.forename: J
authors.initials: J
authors.lastname: Falcón
authors.forename: J A
authors.initials: JA
authors.lastname: Muñoz-Cueto
mesh_terms: D000121:Acetylserotonin O-Methyltransferase / Q000235:genetics / Q000378:metabolism; D000818:Animals; D047068:Arylalkylamine N-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D001492:Bass / Q000235:genetics / Q000378:metabolism*; D001921:Brain / Q000166:cytology / Q000378:metabolism; D002940:Circadian Rhythm; D007150:Immunohistochemistry; D008027:Light; D008550:Melatonin / Q000378:metabolism; D010870:Pineal Gland / Q000033:anatomy & histology / Q000201:enzymology / Q000378:metabolism; D016133:Polymerase Chain Reaction; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology / Q000378:metabolism; D017948:Retinal Rod Photoreceptor Cells / Q000166:cytology / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism
chemical_list: D012701:Serotonin; D000121:Acetylserotonin O-Methyltransferase; D047068:Arylalkylamine N-Acetyltransferase; D008550:Melatonin