Wang Wei, Zhu Hua, Dong Ying, Tian ZhaoHui, Dong Tian, Hu HongXia, Niu CuiJuan
Beijing Normal University, No. 19 Xin Jie Kou Wai Avenue, Haidian District, Beijing, 100875, China.
National Freshwater Fisheries Engineering Technology Research Center, Ministry of Science and Technology of China, Beijing Key Laboratory of Fishery Biotechnology (No. BZ0301), Beijing Fisheries Research Institute, No.18 Ma Jia Pu Road, Fengtai District, Beijing, 100068, China.
Fish Physiol Biochem. 2017 Dec;43(6):1557-1569. doi: 10.1007/s10695-017-0392-x. Epub 2017 Sep 29.
Molecular mechanism of sex determination and differentiation of sturgeon, a primitive fish species, is extraordinarily important due to the valuable caviar; however, it is still poorly known. The present work aimed to identify the major genes involved in regulating gonadal development of sterlet, a small species of sturgeon, from 13 candidate genes which have been shown to relate to gonadal differentiation and development in other teleost fish. The sex and gonadal development of sterlets were determined by histological observation and levels of sex steroids testosterone (T), 11-ketotestosterone (11-KT), and 17β-estradiol (E2) in serum. Sexually dimorphic gene expressions were investigated. The results revealed that gonadal development were asynchronous in 2-year-old male and female sterlets with the testes in early or mid-spermatogenesis and the ovaries in chromatin nucleolus stage or perinucleolus stage, respectively. The levels of T and E2 were not significantly different between sexes or different gonadal development stages while 11-KT had the higher level in mid-spermatogenesis testis stage. In all the investigated gonadal development stages, gene dmrt1 and hsd11b2 were expressed higher in male whereas foxl2 and cyp19a1 were expressed higher in female. Thus, these genes provided the promising markers for sex identification of sterlet. It was unexpected that dkk1 and dax1 had significantly higher expression in ovarian perinucleolus stage than in ovarian chromatin nucleolus stage and in the testis, suggesting that these two genes had more correlation with ovarian development than with the testis, contrary to the previous reports in other vertebrates. Testicular development-related genes (gsdf and amh) and estrogen receptor genes (era and erb) differentially expressed at different testis or ovary development stages, but their expressions were not absolutely significantly different in male and female, depending on the gonadal development stage. Expression of androgen receptor gene ar or rspo, which was supposed to be related to ovarian development, presented no difference between gonadal development stages investigated in this study whenever in male or female.
鲟鱼是一种原始鱼类，由于其珍贵的鱼子酱，其性别决定和分化的分子机制格外重要；然而，目前人们对其了解仍然很少。本研究旨在从13个已被证明与其他硬骨鱼性腺分化和发育相关的候选基因中，鉴定出参与调节小体鲟性腺发育的主要基因。通过组织学观察以及血清中性类固醇睾酮（T）、11-酮睾酮（11-KT）和17β-雌二醇（E2）的水平来确定小体鲟的性别和性腺发育情况。研究了性别二态性基因的表达。结果显示，2岁的雄性和雌性小体鲟性腺发育不同步，雄性睾丸处于精子发生早期或中期，雌性卵巢处于染色质核仁期或核仁周围期。T和E2的水平在不同性别或不同性腺发育阶段之间没有显著差异，而11-KT在精子发生中期的睾丸阶段水平较高。在所有研究的性腺发育阶段，基因dmrt1和hsd11b2在雄性中表达较高，而foxl2和cyp19a1在雌性中表达较高。因此，这些基因有望成为小体鲟性别鉴定的标记。出乎意料的是，dkk1和dax1在卵巢核仁周围期的表达显著高于卵巢染色质核仁期和睾丸中的表达，这表明这两个基因与卵巢发育的相关性比与睾丸的相关性更强，这与之前在其他脊椎动物中的报道相反。与睾丸发育相关的基因（gsdf和amh）以及雌激素受体基因（era和erb）在不同的睾丸或卵巢发育阶段差异表达，但它们在雄性和雌性中的表达并没有绝对显著差异，这取决于性腺发育阶段。雄激素受体基因ar或rspo的表达，本应与卵巢发育相关，但在本研究中所调查的性腺发育阶段，无论在雄性还是雌性中均无差异。
