title: Induction of gonadal maturation at different temperatures in burbot Lota lota.
abstract: A rearing experiment was conducted to test whether temperature protocols that differed from a simulation of natural conditions might induce maturation after isothermal grow-out in burbot Lota lota. Lota lota were acclimated to two different temperature regimes: low temperature (LT), close to natural temperature at 4·0° C and elevated, high temperature (HT) at 8·5° C over 40 and 27 days respectively, with all fish then wintered for 47 days. Every second fish was treated with a gonadotropin-releasing hormone analogue. Maturational competence of oocytes was assessed with a germinal vesicle breakdown assay using a novel staining strategy. In both treatments, puberty and maturational progress occurred, characterised by an elevated gonado-somatic index and advanced gonadal stages (histological analysis). Progress of gonadal maturation was reflected by elevated plasma concentrations of testosterone and 11-ketosterone in males and 17β-oestradiol in females. Ovulation was not observed. Sperm could be activated equally across treatments. In general, LT was more effective than HT treatment, indicated by advanced gonadal stages, higher numbers of oocytes undergoing germinal vesicle breakdown in vitro and elevated sex steroid levels. Hormone treatment could improve effectiveness at HT. In conclusion, less drastic temperature regimes as previously reported in combination with hormone treatments seem sufficient to induce maturation in L. lota after isothermal grow-out.
authors.affiliation: Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Dept. Ecophysiology and Aquaculture, Müggelseedamm 310, 12587, Berlin, Germany.|Humboldt-Universität zu Berlin, Faculty of Life Sciences, Thaer Institute of Agricultural and Horticultural Sciences, Invalidenstraße 42, 10099, Berlin, Germany.
authors.forename: F J
authors.initials: FJ
authors.lastname: Schaefer
authors.affiliation: Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Dept. Ecophysiology and Aquaculture, Müggelseedamm 310, 12587, Berlin, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Hermelink
authors.affiliation: Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Dept. Ecophysiology and Aquaculture, Müggelseedamm 310, 12587, Berlin, Germany.|Freie Universität Berlin, Department of Biology, Chemistry and Pharmacy, Takustraße 3, 14195, Berlin, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Husmann
authors.affiliation: Aqua-ERF, Odisee University College, Hospitaalstraat 23, 9100, Sint-Niklaas, Belgium.
authors.forename: W
authors.initials: W
authors.lastname: Meeus
authors.affiliation: Aqua-ERF, Odisee University College, Hospitaalstraat 23, 9100, Sint-Niklaas, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Adriaen
authors.affiliation: Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Dept. Ecophysiology and Aquaculture, Müggelseedamm 310, 12587, Berlin, Germany. wuertz@igb-berlin.de.|Humboldt-Universität zu Berlin, Faculty of Life Sciences, Thaer Institute of Agricultural and Horticultural Sciences, Invalidenstraße 42, 10099, Berlin, Germany. wuertz@igb-berlin.de.
authors.forename: S
authors.initials: S
authors.lastname: Wuertz
mesh_terms: D000818:Animals; D003080:Cold Temperature; D004958:Estradiol / Q000097:blood; D005260:Female; D005399:Fishes; D048388:Gadiformes / Q000033:anatomy & histology / Q000097:blood / Q000254:growth & development*; D007987:Gonadotropin-Releasing Hormone; D006066:Gonads; D008297:Male; D009865:Oocytes; D010053:Ovary / Q000033:anatomy & histology / Q000254:growth & development*; D010060:Ovulation; D011897:Random Allocation; D012621:Seasons; D012741:Sexual Maturation; D013094:Spermatozoa; D013696:Temperature; D013737:Testis / Q000033:anatomy & histology / Q000254:growth & development*; D013739:Testosterone / Q000097:blood
chemical_list: D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D004958:Estradiol
keywords: broodstock management; oogenesis; puberty; reproduction; sex steroids; spermatogenesis