title: Intra-pituitary relationship of follicle stimulating hormone and luteinizing hormone during pubertal development in Atlantic bluefin tuna (Thunnus thynnus).
abstract: As part of the endeavor aiming at the domestication of Atlantic bluefin tuna (BFT; Thunnus thynnus), first sexual maturity in captivity was studied by documenting its occurrence and by characterizing the key hormones of the reproductive axis: follicle stimulating hormone (FSH) and luteinizing hormone (LH). The full length sequence encoding for the related hormone β-subunits, bftFSHβ and bftLHβ, were determined, revealing two bftFSHβ mRNA variants, differing in their 5' untranslated region. A quantitative immuno-dot-blot assay to measure pituitary FSH content in BFT was developed and validated enabling, for the first time in this species, data sets for both LH and FSH to be compared. The expression and accumulation patterns of LH in the pituitary showed a steady increase of this hormone, concomitant with fish age, reaching higher levels in adult females compared to males of the same age class. Conversely, the pituitary FSH levels were elevated only in 2Y and adult fish. The pituitary FSH to LH ratio was consistently higher (>1) in immature than in maturing or pubertal fish, resembling the situation in mammals. Nevertheless, the results suggest that a rise in the LH storage level above a minimum threshold may be an indicator of the onset of puberty in BFT females. The higher pituitary LH levels in adult females over males may further support this notion. In contrast three year-old (3Y) males were pubertal while cognate females were still immature. However, it is not yet clear whether the advanced puberty in the 3Y males was a general feature typifying wild BFT populations or was induced by the culture conditions. Future studies testing the effects of captivity and hormonal treatments on precocious maturity may allow for improved handling of this species in a controlled environment which would lead to more cost-efficient farming.
authors: Israel Oceanographic and Limnological Research, National Center for Mariculture, Eilat, Israel; Department of Life Sciences, Ben-Gurion University, Eilat Campus, Eilat, Israel.
authors: Nadia
authors: N
authors: Berkovich
authors: Aldo
authors: A
authors: Corriero
authors: Nicoletta
authors: N
authors: Santamaria
authors: Constantinos C
authors: CC
authors: Mylonas
authors: Robert
authors: R
authors: Vassallo-Aguis
authors: Fernando
authors: F
authors: de la Gándara
authors: Iris
authors: I
authors: Meiri-Ashkenazi
authors: Vered
authors: V
authors: Zlatnikov
authors: Hillel
authors: H
authors: Gordin
authors: Christopher R
authors: CR
authors: Bridges
authors: Hanna
authors: H
authors: Rosenfeld
mesh_terms: D000818:Animals; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism*; D014413:Tuna / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone
keywords: Atlantic bluefin tuna; Dot-blot-immunoassay; Fish reproduction; Gonadotropins; Puberty; Sexual dimorphism