Schaefer F J, Hermelink B, Husmann P, Meeus W, Adriaen J, Wuertz S
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.
J Fish Biol. 2016 Nov;89(5):2268-2281. doi: 10.1111/jfb.13107. Epub 2016 Sep 20.
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.
进行了一项饲养实验，以测试与自然条件模拟不同的温度方案是否可能在江鳕（Lota lota）等温养殖后诱导其成熟。江鳕分别在40天和27天内适应两种不同的温度 regime：低温（LT），接近4.0°C的自然温度；高温（HT），8.5°C，然后所有鱼都越冬47天。每隔一条鱼用促性腺激素释放激素类似物处理。使用一种新颖的染色策略，通过生发泡破裂试验评估卵母细胞的成熟能力。在两种处理中，都出现了青春期和成熟进程，其特征是性腺-体指数升高和性腺阶段提前（组织学分析）。性腺成熟的进程通过雄性血浆中睾酮和11-酮睾酮以及雌性血浆中17β-雌二醇浓度的升高来反映。未观察到排卵。各处理间精子均可同等程度地被激活。总体而言，LT处理比HT处理更有效，表现为性腺阶段提前、体外生发泡破裂的卵母细胞数量更多以及性类固醇水平升高。激素处理可提高HT处理的有效性。总之，与之前报道的相比，不太剧烈的温度方案与激素处理相结合似乎足以在等温养殖后诱导江鳕成熟。
