larvi 213 6th fish & shellfish larviculture symposium Pubertal development of Atlantic Bluefin tuna (Thunnus thynnus) in captivity Berkovich Nadia ghent university, belgium, 2- september 213
The key neuroendocrine regulators of the onset of puberty in the Atlantic bluefin tuna (Thunnus thynnus) Nadia Berkovich, Iris Meiri-Ashkenazi, Vered Zlatnikov, Aldo Corriero, Christopher Bridges, Constantinos Mylonas, Robert Vassallo Aguis, Fernando De La Gándara, Antonio Belmonte, Abigail Elizur, Hillel Gordin and Hanna Rosenfeld Israel Oceanographic and Limnological Research Ben-Gurion University of the Negev
Bluefin tuna opens 213 with record auction price at Tsukiji: 1.78 million dollars MercoPress, Jan 213
Distribution Mediterranean Sea Gulf of Mexico
Puberty The period during which the capability of sexual reproduction is attained
Hypothalamic-Pituitary-Gonadal Axis Hypothalamus GnRH Pituitary FSH, LH Gonad Gonadal peptides Sex steroids
Objectives To evaluate the maturational competence of the reproductive axis in juvenile tuna reared in captivity (Experiment I). To assess the competence of the gonads to respond in vitro to exogenous hormones (Experiment II). Hypothalamus GnRH Pituitary FSH, LH Gonad
Experiment I July 29, Croatia
Experiment I: Sampling young tuna Biometric data, including: total length, weigh (body & gonads), GSI values Tissue sampling, including: brain, pituitary, gonads & first spine
Experiment I: Age determination Sections of the first spiniform ray of juvenile tuna 2 years old fish BW: 8.4±.41 kg FL: 82.8±1.3 cm 3 years old fish BW: 19.38±.7 kg FL: 12.8±.98 cm University of Bari, Italy
Experiment I: Histology Sex and reproductive state of juvenile tuna An ovary section (3Y) A Perinucleolar stage was the most advanced oocyte stage A testis section (3Y) B All the spermatogenetic stages, as well as spermatozoa University of Bari, Italy
Check points along HPG axis Hypothalamus Pituitary Hormones: FSH, LH Gonadotropin subunits: FSHβ, LHβ Hypothalamus GnRH Pituitary FSH, LH Gonad Experiment I Gonad
Experiment I: Hormonal analysis Pituitary LH ( g per pit per kg M B ) Pituitary LH Pituitary A 3 2 2 1 B 1 C C BC BC 2Y 3Y Y Male 2Y 3Y Y Female
Experiment I: Hormonal analysis Pituitary FSH Pituitary
Experiment I: Hormonal analysis Mature individuals: FSH/LH 1 Immature individuals: FSH/LH > 1 Pituitary FSH/LH Ratio Pituitary FSH/LH ratio 6 Pituitary A 4 3 AB 2 B 1 B B 2Y 3Y Y Male 2Y B 3Y Y Female
Experiment I: Summary The 3-Y males exhibited advanced puberty compared to females of the same age class. The pituitary LH content increased concomitantly with the age of the fish. Sexual dimorphic pituitary LH patterns were observed in fully mature BFT (3-fold higher in females). The intra-pituitary FSH/LH ratio in sexually immature 2-Y BFT is relatively higher (>1) than in maturing or pubertal fish.
Experiment I: Summary It appears that the onset of puberty in females necessitates also a rise in the pituitary LH storage above a minimum threshold.
Aimed to verify the responsiveness of the HPG axis to exogenous hormones. Experiment II June 21, Croatia
Experiment II: In vivo In vivo Kiss/KissR Hypothalamus GnRH Kiss EVAc implants GnRHa EVAc implants Untreated(control) Pituitary FSH, LH Gonad
Experiment II: Sampling strategy Histology GtHs & Sex steroids qrt-pcr
Experiment II: In vitro Tuna juveniles: 1. Untreated (control) 2. GnRHa-implanted 3. Kiss-implanted 3 weeks prior to sampling
Experiment II: Hormonal analysis Effects of rgths on sex steroid secretion 1 11KT (ng/ml/g gonad) 11KT (ng/ml/g gonad) Immature tuna (control) 1 r BFT-FSH (ng/ml) 3 2 1 rbft-fsh (ng/ml) 1 1 E2 (ng/ml/g gonad) E2 (ng/ml/g gonad) 1 1 rbft-lh (ng/ml) rbft-lh (ng/ml) 4 3 2 1
Experiment II: Hormonal analysis Effects of rgths on sex steroid secretion 1 A AB AB 1 B 1 1 bft-fsh (ng/ml) 1 AB 2 1 A AB 1 B bft-fsh (ng/ml) 2 2 1 E2 (ng/ml/g gonad) E2 (ng/ml/g gonad) AB 11KT (ng/ml/g gonad) 11KT (ng/ml/g gonad) Immature tuna pretreated with GnRH bft-lh (ng/ml) 8 6 4 2 bft-lh (ng/ml)
Experiment II: Hormonal analysis Effects of rgths on sex steroid secretion 1 B 8 AB AB 6 4 B A 2 11KT (ng/ml/g gonad) 11KT (ng/ml/g gonad) Immature tuna pretreated with Kiss 6 4 2 1 1 8 6 E2 (ng/ml/g gonad) E2 (ng/ml/g gonad) bft-fsh (ng/ml) bft-lh (ng/ml) 1. Pretreatment with Kiss seems to 1. potentiate the responsiveness of the 4 2.. testes to FSH bft-fsh (ng/ml) 1 bft-lh (ng/ml)
Experiment II: Effects of rgth on gonadal growth 6 B B A 4 3 1 rfsh (ng/ml) University of Bari, Italy 7 Seminiferous tubule diameter ( m) Seminiferous tubule diameter ( m) 7 Early spermatogenesis 6 A A 2 B 4 3 1 2 rlh (ng/ml)
Experiment II: Summary Neither bftfsh nor bftlh induced steroidogenesis in control group. Nevertheless, bftfsh and bftlh stimulated gonadal growth.
Next challenge: Advance puberty in captive tuna juveniles
Lab members: Dr. Hanna Rosenfeld Dr. Iris Meiri Vered Zlatnikov Hanit Ben-Ari Dr. Rachel Armoza-Zvuloni Hagit Kvitt