Cloning of FSH‐β, LH‐β and glycoprotein hormone α subunits in pejerrey Odontesthes bonariensis (Valenciennes): expression profile and relationship with GnRH expression and plasma sex steroid levels in male fish

Abstract

Three cDNAs encoding pejerrey Odontesthes bonariensis follicle stimulating hormone‐β (FSH‐β), luteinizing hormone‐β (LH‐β) and glycoprotein‐α (GPH‐α) subunits were cloned and characterized. Gene expression of these subunits was analysed by real‐time polymerase chain reaction (PCR) and compared with the brain gene expression of endogenous gonadotropin‐releasing hormones (GnRHs): Pacific salmon GnRH (GnRH‐III), pejerrey GnRH (GnRH‐I) and chicken GnRH‐II (GnRH‐II) and plasma sex steroid levels in adult males. The nucleotide sequences of the FSH‐β, LH‐β and GPH‐α subunits are 466, 558 and 677 base pairs long, encoding for mature peptides of 102, 118 and 98 amino acids respectively. Maturing males had high expression of FSH‐β and GPH‐α subunits, and intermediate levels of LH‐β when compared with running ripe and spent stages. These animals had the lowest plasma testosterone (T) and 11‐ketosterone (11‐KT) values as well as low expression of sGnRH, cGnRH‐II and pjGnRH. Running ripe males had the lowest expression of FSH‐β and the highest expression of LH‐β and GPH‐α subunits, and of the three GnRH genes. At this stage, the highest values of T and 11‐KT were observed. Spent males showed low expression of the three gonadotropin (GtH) subunits, sGnRH, pjGnRH and low levels of T. At this stage, 11‐KT levels and cGnRH‐II expression showed a tendency to decrease but the values were not statistically significant ( P

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