尼罗罗非鱼卵巢发育过程中性类固醇激素与卵黄蛋白原含量变化及Vtg mRNA表达特征 [中文引用][英文引用]

通过组织切片、酶联免疫吸附及荧光定量PCR等方法, 研究了尼罗罗非鱼(<i>Oreochromis niloticus</i>)卵巢发育过程中性类固醇激素(雌二醇E₂、孕酮P)、卵黄蛋白原(Vtg)含量及<i>Vtg</i> mRNA相对表达水平变化规律.结果表明, 尼罗罗非鱼性腺指数(GSI)与卵巢成熟发育间呈同步性变化, V期达到峰值.血清中E₂含量自卵巢II期开始显著升高, IV期达到峰值, V期后显著下降; 血清P含量自卵巢II期开始不断升高, V期达到峰值, VI期显著下降; E₂、P分别在卵巢成熟发育前期与后期发挥作用.肝中Vtg含量先升、后降, IV期达峰值; 血清、卵巢中Vtg含量均自II期开始增加, V期达峰值, VI期显著降低; 不同组织中Vtg含量变化与卵巢成熟发育间存在密切关联.肝中<i>Vtg</i> mRNA表达水平在III期达到峰值, IV期后持续下调; 卵巢中<i>Vtg</i> mRNA表达水平相对较低, V期达到峰值; 初步推测肝、卵巢同是尼罗罗非鱼Vtg合成部位, 肝是Vtg合成的主要器官, 在卵黄积累阶段最为活跃, 而卵巢Vtg合成水平相对较低.

Tilapia feature asynchronous oocyte development and batch spawning. We conducted this study to further understand ovarian maturation and the physiological mechanisms involved in non-synchronous spawners, such as tilapia. Changes in sex steroid hormones (estradiol-17β[E₂] and progesterone [P]), vitellogenin (Vtg) levels, and <i>Vtg</i> mRNA expression were studied during ovarian development in <i>Oreochromis </i><i>niloticus </i>using histological, enzyme-linked immunoassay, and quantitative reverse transcription-polymerase chain reaction methods, respectively. The results showed that the gonadosomatic index (GSI) of <i>O. niloticus </i>paralleled ovarian development and peaked at stage V. Serum E₂levels increased significantly beginning at stage II, peaked at stage IV, then decreased significantly at stage V, whereas P levels increased gradually beginning at stage II, peaked at stage V, and decreased significantly at stage VI. Hepatic <i>Vtg</i> content increased initially, decreased, and then peaked at stage IV. Serum and ovarian Vtg contents increased gradually beginning at stage II, peaked at stage V, and decreased significantly at stage VI. Hepatic <i>Vtg</i> mRNA expression peaked at stage III and decreased gradually atstage IV. Ovarian <i>Vtg</i> mRNA expression was relatively lower and peaked at stage V. These results indicate that E₂and P play different roles during the early and late ovarian developmental stages, respectively. A close correlation was detected between changes in Vtg content in different tissues and ovarian maturation.<i>Vtg</i> mRNA from the liver and ovary were involved in Vtg synthesis; the liver is the major synthetic organ active during the yolk accumulation phase, but ovarian Vtg synthesis was relatively low.We provide some basic data to further explore the endocrine regulatory mechanisms in non-synchronous spawning fish.