title: Developmental expression of three forms of gonadotropin-releasing hormone and ontogeny of the hypothalamic-pituitary-gonadal axis in gilthead seabream (Sparus aurata).
abstract: To address the complexity of the origin of the GnRH system in perciforms, we investigated the ontogenic expression of three GnRHs in gilthead seabream. Using in situ hybridization, chicken (c) GnRH-II mRNA-expressing cells were detected in the hindbrain at 1.5 days postfertilization (DPF) and in the midbrain at 2 DPF and thereafter; the hindbrain signals became undetectable after 10 DPF. Salmon (s) GnRH mRNA-expressing cells were first seen in the olfactory placode at 3 DPF, started caudal migration at 14 DPF, and reached the preoptic areas at 59 DPF. Seabream (sb) GnRH mRNA-expressing cells were first detected in the terminal nerve ganglion cells (TNgc), ventral part of the ventral telencephalon, nucleus preopticus parvocellularis, and thalamus at 39 DPF, and extended to the nucleus preopticus magnocellularis at 43 DPF, ventrolateral hypothalamus at 51 DPF, and nucleus lateralis tuberis and posterior tuberculum at 59 DPF. Coexpression of sbGnRH and sGnRH transcripts was found in the TNgc. Using real-time fluorescence-based quantitative polymerase chain reaction, transcript levels of cGnRH-II and sGnRH were first detected at 1 and 1.5 DPF, respectively, and increased and remained high thereafter. Transcript levels of sbGnRH remained low after first detection at 1 DPF. Furthermore, these GnRH expression profiles were correlated with the expression profiles of reproduction-related genes in which at least four concomitant increases of GnRH, GnRH receptor, gonadotropin, gonadotropin receptor, and Vasa transcripts were found at 5, 8, 14, and 28 DPF. Our data provide an expanded view of the ontogeny of the GnRH system and reproductive axis in perciforms.
authors.affiliation: Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, Maryland 21202, USA.
authors.forename: Ten-Tsao
authors.initials: TT
authors.lastname: Wong
authors.forename: Yoav
authors.initials: Y
authors.lastname: Gothilf
authors.forename: Nilli
authors.initials: N
authors.lastname: Zmora
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Kight
authors.forename: Iris
authors.initials: I
authors.lastname: Meiri
authors.forename: Abigail
authors.initials: A
authors.lastname: Elizur
authors.forename: Yonathan
authors.initials: Y
authors.lastname: Zohar
mesh_terms: D000818:Animals; D017756:Aquaculture; D005260:Female; D037201:Follicle Stimulating Hormone, beta Subunit / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics*; D007030:Hypothalamo-Hypophyseal System / Q000196:embryology* / Q000502:physiology*; D037101:Luteinizing Hormone, beta Subunit / Q000235:genetics; D010053:Ovary / Q000196:embryology / Q000502:physiology; D010902:Pituitary Gland / Q000196:embryology* / Q000502:physiology*; D020365:RNA Helicases / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D011962:Receptors, FSH / Q000235:genetics; D011974:Receptors, LH / Q000235:genetics; D011966:Receptors, LHRH / Q000235:genetics; D012098:Reproduction / Q000502:physiology; D021541:Sea Bream / Q000502:physiology*
chemical_list: D037201:Follicle Stimulating Hormone, beta Subunit; D037101:Luteinizing Hormone, beta Subunit; D012333:RNA, Messenger; D011962:Receptors, FSH; D011974:Receptors, LH; D011966:Receptors, LHRH; D007987:Gonadotropin-Releasing Hormone; D020365:RNA Helicases