SEX STEROID PROFILES OF COHO SALMON (ONCORHYNCHUS-KISUTCH) DURING EARLY DEVELOPMENT AND SEXUAL-DIFFERENTIATION
SEX STEROID PROFILES OF COHO SALMON (ONCORHYNCHUS-KISUTCH) DURING EARLY DEVELOPMENT AND SEXUAL-DIFFERENTIATION
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DOI：
10.1016/0016-6480(90)90174-k
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发表时间：
1990-11-01
影响因子：
2.7
通讯作者：
REDDING, JM
中科院分区：
文献类型：
--
作者：
FEIST, G;SCHRECK, CB;REDDING, JM
用放射免疫法测定了银鲑（Oncorhynchus kisutch）早期发育和性分化过程中的性类固醇激素含量。从受精时间到受精后87天（dpf），对鱼开发六种类固醇的分布图：睾酮（T）、11-酮睾酮（KT）、雄烯二酮（A）、孕酮（P4）、17 α-孕酮（P4）。羟基-20 β-二氢孕酮（DHP）和17 β-雌二醇（E2）。还检查了卵巢液中的类固醇含量。未受精卵的类固醇含量基本上与卵巢液相同。在一个实验中，类固醇在发育中的胚胎下降急剧受精后，直到30 dpf;在孵化，所有类固醇略有增加，然后下降在卵黄囊吸收。第二个实验的结果基本上支持了第一个实验的结果，除了只有睾酮在孵化时增加。双峰是显而易见的，在42和56 dpf和87 dpf后再次收集鱼的类固醇水平的数据。激素水平一般下降或保持恒定后开始外源性喂养。第一次实验期间的组织学分析显示，在孵化和70 dpf之间存在未分化的性腺，但到77 dpf卵巢发育明显。在第二个实验中，鱼更频繁地取样进行组织学分析，未分化的性腺从孵化到59 dpf。卵原细胞的发育在66 - 73 dpf之间观察到，到75 dpf卵巢发育可以容易地辨别。在101 dpf取样的鱼的性别通过检查性腺形态来确定，并确定这些鱼的类固醇水平。性二态性是明显的T，KT和A的水平，但不是DHP或E2。发育中的银鲑在孵化时的类固醇含量的动态，再加上他们的双峰分布在卵黄囊吸收过程中，可能表明性类固醇激素的作用，在性分化的过程中明显的发展。孵化时全身类固醇水平的变化也可能表明性分化的开始，即使当时没有贡达尔分化的迹象。
Sex steroids were measured by radioimmunoassay in whole-body extracts of coho salmon, Oncorhynchus kisutch, during early development and sexual differentiation. Profiles were developed for fish from the time of fertilization until 87 days postfertilization (dpf) for six steroids: testosterone (T), 11-ketotestosterone (KT), androstenedione (A), progesterone (P4), 17.alpha.-hydroxy-20.beta.-dihydroprogesterone (DHP), and 17.beta.-estradiol (E2). Ovarian fluid was also examined for steroid content. Steroid profiles of unfertilized eggs essentially paralleled those of ovarian fluid. In one experiment, steroids in developing embryos declined precipitously after fertilization until 30 dpf; at hatching, all steroids increased slightly and then declined during yolk sac absorption. Results from a second experiment basically supported those of the first except that only testosterone increased at the time of hatching. Bimodality was evident in the data on steroid levels for fish collected between 42 and 56 dpf and again after 87 dpf. The hormone levels generally decreased or remained constant after the onset of exogenous feeding. Histological analyses during the first experiment showed the presence of undifferentiated gonads between hatching and 70 dpf, but by 77 dpf ovarian development was evident. In the second experiment, in which fish were more frequently sampled for histological analysis, undifferentiated gonads were present from hatching to 59 dpf. Development of oogonia was observed between 66 and 73 dpf and by 75 dpf ovarian development could be easily discerned. The sex of fish sampled at 101 dpf was determined by examining gonadal morphology, and steroid levels of those fish were determined. A sexual dimorphism was apparent in levels of T, KT, and A, but not of DHP or E2. The dynamics of steroid content of developing coho salmon at hatch, coupled with their bimodal distributions during yolk sac absorption, may suggest a role of sex steroids in the process of sexual differentiation apparent later in development. Changes in whole-body steroid levels at hatch may also be indicative of the onset of sexual differentiation even though no signs of gondal differentiation were histologically discernible at that time.