花鲈性腺分化组织学及性别相关基因cyp11b和cyp19a1a的表达分析

Histology of gonadal differentiation and expression analysis of sex-related genes cyp11b and cyp19a1a in spotted sea bass (Lateolabrax maculatus)

关键词:  花鲈  性别分化  组织学  cyp11b  cyp19a1a

Key words:  Lateolabrax maculatus  Gonad differentiation  Histology  cyp11b  cyp19a1a

摘要:

以花鲈(Lateolabrax maculatus) 1~214 dph (day post hatching)的仔稚鱼、幼鱼以及18月龄的雌鱼和雄鱼为研究对象，研究了花鲈早期性腺发生、发育和分化情况；分析了性腺分化过程中性别相关基因(cyp11b和cyp19a1a)的表达及与性别之间的关系。结果显示，在30 dph [全长为(1.28± 0.10) cm]，首次在中肾管前端的腹腔膜周围观察到原始生殖细胞(primordial germ cells, PGCs)，说明30 dph前是花鲈胚后PGCs迁移至生殖嵴的关键时期；在55 dph [全长为(2.45±0.19) cm]，观察到一对呈对称分布的原始性腺已经形成，说明花鲈幼鱼的原始性腺在30~55 dph (全长为1.28~2.45 cm)之间发生；55~180 dph时(全长为2.45~12.28 cm)，原始性腺不断发育变大，并且一直处于未分化状态；180 dph后性腺开始分化；在195 dph [全长(14.54±1.54) cm]观察到精巢开始分化，卵巢于205 dph [全长为(15.86±0.94) cm]开始分化，且性腺的解剖学分化要早于细胞学分化；18月龄的花鲈幼鱼性腺发育到Ⅱ期。性别分化相关基因cyp19a1a在花鲈卵巢中的表达量高于同期精巢，说明其在卵巢的分化及维持中发挥更关键的作用，而cyp11b在18月龄幼鱼Ⅱ期精巢中的表达量显著高于同时期的卵巢及Ⅰ期精巢，说明其主要在精巢的分化及维持中扮演重要角色。本研究结果不仅可以丰富花鲈的繁殖生理学资料，也为其性别调控技术的研究提供了科学依据。

Abstract:

The gonadogenesis, the development and differentiation of larvae and juveniles from 1~214 days post hatching (dph) and 18-month-old female and male spotted sea bass (Lateolabrax maculatus) were studied. The relationship between the expression of sex-related genes (cyp11b and cyp19a1a) and sex in the process of gonadal differentiation was discussed. The results showed that at 30 dph [(1.28±0.10) cm], primordial germ cells (PGCs) were first observed around the peritoneal membrane at the front end of the mesorenic duct, indicating that the time before 30 dph was the critical period for PGCs to migrate to the genital ridge. At 55 dph [(2.45±0.19) cm], a pair of symmetrically distributed primitive gonads was observed, indicating that the primitive gonads of the juvenile spotted sea bass were formed between 30 and 55 dph [(1.28~2.45) cm]. Between 55~180 dph [(2.45~12.28) cm], the primordial gonads continued to grow and remained in an undifferentiated state. After 180 dph, the gonads began to differentiate; at 195 dph [(14.54±1.54) cm], we observed that the testis began to differentiate, while the ovary began to differentiate at 205 dph [(15.86±0.94) cm]. The anatomical differentiation of the gonads was earlier than the cytological differentiation in spotted sea bass. The gonad of 18-month-old spotted sea bass developed to stageⅡ. The expression level of the sex differentiation-related gene cyp19a1a in the ovary of spotted sea bass was higher than that of the contemporaneous testis, indicating that it played a key role in the differentiation and maintenance of the ovary. The expression level of cyp11b at stageⅡ testis of 18-month-old juveniles was significantly higher than in the contemporaneous ovary and stage Ⅰ testes, suggesting that it played a crucial part in the differentiation and maintenance of testes. The results not only enriched our understanding of the reproductive physiology of spotted sea bass, but also provided a scientific basis for the study of sex selection technology.