title: Developmental changes and day-night expression of the gonadotropin-inhibitory hormone system in the European sea bass: Effects of rearing temperature.
abstract: The role of rearing temperature on fish development, sex differentiation and puberty has been largely addressed, but the impact of water temperature on the ontogeny of the main neuroendocrine systems controlling reproduction has received little attention. Gonadotropin-inhibitory hormone (GnIH) has been shown to act on gonadotropin-releasing hormone (GnRH) neurons and on the pituitary to inhibit gonadotropin release and synthesis in vertebrates, including sea bass, Dicentrarchus labrax. In the present study we investigated the effects of rearing temperature during the thermosensitive period (5-60days post-fertilization, dpf) on the expression of the GnIH gene (gnih) and its receptor (gnihr). Animals were maintained under two different conditions, low temperature (LT, 15°C) or high temperature (HT, 21°C), throughout the thermosensitive period and sampled from 5 to 360dpf at mid-light (ML) and mid-dark (MD). Our results showed significant effects of temperature on gnih and gnihr expression during the thermosensitive period, with higher transcript levels under LT condition. Some differences were also evident after the completion of the sex differentiation process. Moreover, we revealed daily variations in the developmental expression of gnih and gnihr, with higher diurnal mRNA levels at early stages (until 25dpf), and a shift to higher nocturnal expression levels at 300-360dpf, which corresponded with the beginning of the winter (reproductive season). To the best of our knowledge, this work represents the first study reporting the effects of rearing temperature on the transcription of gnih system genes, as well as its daily variations during the development of a fish species.
authors.affiliation: Department of Biology, Faculty of Environmental and Marine Sciences, University of Cádiz, Marine Campus of International Excellence (CEIMAR) and Agrifood Campus of International Excellence (ceiA3), E-11510 Puerto Real, Spain; INMAR-CACYTMAR Research Institutes, Puerto Real University Campus, E-11510 Puerto Real, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Paullada-Salmerón
authors.affiliation: Department of Biology, Faculty of Environmental and Marine Sciences, University of Cádiz, Marine Campus of International Excellence (CEIMAR) and Agrifood Campus of International Excellence (ceiA3), E-11510 Puerto Real, Spain; INMAR-CACYTMAR Research Institutes, Puerto Real University Campus, E-11510 Puerto Real, Spain.
authors.forename: Guillaume Henri
authors.initials: GH
authors.lastname: Loentgen
authors.affiliation: Department of Biology, Faculty of Environmental and Marine Sciences, University of Cádiz, Marine Campus of International Excellence (CEIMAR) and Agrifood Campus of International Excellence (ceiA3), E-11510 Puerto Real, Spain; INMAR-CACYTMAR Research Institutes, Puerto Real University Campus, E-11510 Puerto Real, Spain.
authors.forename: Mairi
authors.initials: M
authors.lastname: Cowan
authors.affiliation: Department of Biology, Faculty of Environmental and Marine Sciences, University of Cádiz, Marine Campus of International Excellence (CEIMAR) and Agrifood Campus of International Excellence (ceiA3), E-11510 Puerto Real, Spain; INMAR-CACYTMAR Research Institutes, Puerto Real University Campus, E-11510 Puerto Real, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Aliaga-Guerrero
authors.affiliation: Department of Biology, Faculty of Environmental and Marine Sciences, University of Cádiz, Marine Campus of International Excellence (CEIMAR) and Agrifood Campus of International Excellence (ceiA3), E-11510 Puerto Real, Spain.
authors.forename: María Del Carmen
authors.initials: MD
authors.lastname: Rendón-Unceta
authors.affiliation: Department of Biology, Faculty of Environmental and Marine Sciences, University of Cádiz, Marine Campus of International Excellence (CEIMAR) and Agrifood Campus of International Excellence (ceiA3), E-11510 Puerto Real, Spain; INMAR-CACYTMAR Research Institutes, Puerto Real University Campus, E-11510 Puerto Real, Spain. Electronic address: munoz.cueto@uca.es.
authors.forename: José A
authors.initials: JA
authors.lastname: Muñoz-Cueto
mesh_terms: D000818:Animals; D017756:Aquaculture; D001492:Bass / Q000254:growth & development / Q000502:physiology*; D002940:Circadian Rhythm; D005260:Female; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D006358:Hot Temperature; D007028:Hypothalamic Hormones / Q000235:genetics / Q000378:metabolism*; D007814:Larva / Q000254:growth & development / Q000378:metabolism; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D018013:Receptors, Neuropeptide / Q000235:genetics / Q000378:metabolism*; D019849:Sex Determination Processes; D012741:Sexual Maturation; D000071436:Thermotolerance; D015053:Zygote / Q000254:growth & development / Q000378:metabolism
chemical_list: D029941:Fish Proteins; D007028:Hypothalamic Hormones; D012333:RNA, Messenger; D018013:Receptors, Neuropeptide
keywords: Daily cycles; European sea bass; Gonadotropin-inhibitory hormone (GnIH); Larval development; Puberty; Sex differentiation; Temperature