title: Molecular characterization of sea bass gonadotropin subunits (alpha, FSHbeta, and LHbeta) and their expression during the reproductive cycle.
abstract: Reproduction is controlled by two pituitary gonadotropin hormones, follicle-stimulating hormone (FSH) and luteinizing hormone (LH). This study reports the cloning, sequence analysis, and gene expression of gonadotropin (GTH) subunits from the European sea bass (Dicentrarchus labrax). The GTH subunits were cloned from a sea bass brain-pituitary cDNA library. The nucleotide sequences of the common alpha, the FSHbeta, and the LHbeta subunit cDNAs were 625, 521, and 591 base pair (bp) long, respectively, encoding for mature peptides of 94, 105, and 115 amino acids (aa), respectively. Sequence analysis showed that sea bass FSHbeta is more similar to higher vertebrate FSHbeta's (35-37%) than to LHbeta's (26-30%), whereas sea bass LHbeta is more similar to LHbeta's (40-53%) than to FSHbeta's (26-41%). Phylogenetic analysis of fish GTH sequences grouped the beta subunits into two groups, FSH and LH, distributed into four classes, corresponding to the accepted divisions of Elopomorphs, Ostariophysis, Salmonids, and Percomorphs. A dot-blot technique was developed to analyze GTH pituitary mRNA levels during the reproductive cycle of male sea bass. From October (initiation of gametogenesis) to February (spermiation), the expression of all three subunits in the pituitary increased in parallel, concomitantly with the gonadosomatic index (GSI) and the accumulation of LH protein in the pituitary, all values declining sharply at post-spermiation. This study demonstrates that the pituitary of sea bass contains two gonadotropin hormones and that both gonadotropins are probably involved in the control of gametogenesis, gamete maturation, and spermiation.
authors.affiliation: Instituto de Acuicultura de Torre la Sal (CSIC), Ribera de Cabanes s/n, 12595 Torre la Sal (Castellón), Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: Mateos
authors.forename: Evaristo
authors.initials: E
authors.lastname: Mañanós
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Martínez-Rodríguez
authors.forename: Manuel
authors.initials: M
authors.lastname: Carrillo
authors.forename: Bruno
authors.initials: B
authors.lastname: Querat
authors.forename: Silvia
authors.initials: S
authors.lastname: Zanuy
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001492:Bass / Q000235:genetics*; D003001:Cloning, Molecular; D005260:Female; D037201:Follicle Stimulating Hormone, beta Subunit / Q000737:chemistry / Q000235:genetics*; D015292:Glycoprotein Hormones, alpha Subunit / Q000737:chemistry / Q000235:genetics*; D037101:Luteinizing Hormone, beta Subunit / Q000737:chemistry / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D010902:Pituitary Gland / Q000737:chemistry; D012333:RNA, Messenger / Q000032:analysis; D012098:Reproduction; D012621:Seasons; D016415:Sequence Alignment
chemical_list: D037201:Follicle Stimulating Hormone, beta Subunit; D015292:Glycoprotein Hormones, alpha Subunit; D037101:Luteinizing Hormone, beta Subunit; D012333:RNA, Messenger