条斑星鲽卵巢发育规律和性类固醇激素周年变化研究

The study of gonadal development and steroid hormone annual change in barfin flounder Verasper moseri

关键词:  条斑星鲽  卵巢发育  组织学  性类固醇激素

Key words:  Verasper moseri  Ovary development  Histology  Serum steroid hormone

摘要:

采用组织学方法、形态测量法、放射免疫法（RIA）等技术方法，研究了人工养殖条件下条斑星鲽雌性亲鱼卵巢发育成熟和性类固醇激素的年周期变化规律。结果表明，条斑星鲽属于非同步分批产卵类型。卵母细胞按其组织学特点可分为6个时相，卵巢发育依据其形态特征可划分为相应的6个时期。卵巢年周期发育过程中，性腺指数（GSI）、肝脏指数（HSI）和肥满度（CF）发生变化，表现出与性腺发育协同一致的变化规律。统计分析表明，卵巢年周期发育过程中， GSI和HSI值与CF值都存在显著的正相关关系，GSI值的变化与水温调控呈显著的负相关关系。亲鱼血浆中雌二醇（E2）在6月份开始升高，9月份达到年周期中的第1个小高峰，翌年2月份，E2表达水平达到最高峰值，4月产卵结束后，E2表达水平降低并维持较低水平至下一个生殖季节。血浆中睾酮（T）含量在7月达到第1个峰值，并在翌年1月份达到第2个峰值，在4月份产卵后降至最低水平并维持至下一个生殖季节。统计分析表明，E2与T存在正相关关系，E2与光周期调控存在正相关关系，同时与GSI和CF呈弱的正相关关系。

Abstract:

The annual ovarian maturation cycle and the variation of correlated plasma sex steroids levels were studied by employing light microscopy and morphometric methods combined with radioimmunoassay. In addition, the relationships between GSI, CF, HSI, sex steroids and temperature, photoperiod were investigated through statistical analysis. Results showed that barfin flounder features asynchronous oocyte development and batch spawnings. The oocyte growth included six phases, and six stages in ovary maturation cycle accordingly. Gonadosomatic index (GSI), hepatosomatic index (HSI) and condition factor (CF) were all found to increase prior to, or during the peak phase of vitellogenic growth corresponding to the gonad development. Statistical analysis revealed that GSI was positively correlated with CF while HSI showed negative relationship with CF. Temperature played more important role in regulating the gonad development compared with photoperiod based on the correlation analysis between GSI, temperature and photoperiod. During spawning the serum estradiol level began to increase in June (stage Ⅲ) and reached the first relatively lower peak in September and peaked in February. After the spawning, it dropped down to a relative low level and maintained until the next reproductive cycle. The testosterone level achieved the first relatively high peak in July and peaked in January, which was a month earlier than that of estradiol. A positive relationship was found between estradiol and testosterone level. Statistical analysis revealed that a positive relationship existed between photoperiod and estradiol level. In addition, the estradiol level showed positive correlations with GSI and CF. These results could highlight the reproductive cycle of captive barfin flounder females, and also serve as useful tools for broodstock breeding and determination of timing for hormone induced spawning.