| 摘要: |
| 尽管与性别决定和分化的相关基因在二倍体虹鳟中已被鉴定出来，如 Cyp19a1a、Foxl2、Dmrt1、Amh和 Sox9，但关于三倍体雌性虹鳟独特性腺表型及其相关性别控制基因的表达规律仍未得到深入研究，尤其是早期卵巢发育阻滞导致的生殖细胞去分化特征。因此，本研究以三倍体雌性虹鳟性腺发育中起重要调控作用的特异候选基因作为重点研究对象，辅助性腺体细胞与生殖细胞分化方向的组织学证据和类固醇激素表达规律，验证了各基因间的级联调控关系。结果表明，虹鳟三倍体与二倍体卵巢的分化特征基本一致。虹鳟二倍体与三倍体性腺分别在84dpf和98dpf就已分化为卵巢。但三倍体虹鳟卵巢分化存在障碍，早期发育停滞，卵原细胞及其滤泡细胞数量有限。 Foxl2和 Cyp19a1a在二倍体虹鳟卵巢和精巢中均有表达，它们在卵巢中表达量均呈逐渐升高趋势，但在精巢中的表达量非常低；这两个基因在雌性三倍体虹鳟性腺中的表达呈先升高后降低的趋势，其表达量均在8月龄时期达到最大。 Dmrt1、Amh和 Sox9在二倍体精巢和雌性三倍体卵巢中的表达均呈不断上调趋势，这些基因上调可能与血清睾酮含量的增加相关，因为在10月龄时期这两种鱼的血清含量相对较高，而这三个基因在二倍体虹鳟卵巢中的表达却呈下调趋势。因此本研究认为，维持鱼类卵巢分化需要持续高水平的雌激素，这可能是脊椎动物进化过程中的一个保守特征。可以推断雌性三倍体虹鳟卵巢滞育将导致其体细胞去分化，这对于 Cyp19a1a表达及雌二醇合成存在抑制作用。因为这些雌激素是用来维持它们分化和继续发育的，可能产生一个负反馈圈，之后去分化会增强。 |
| 关键词: 虹鳟 三倍体 雌性通路 卵巢分化 |
| DOI：10.11693/hyhz20161000221 |
| 分类号: |
| 基金项目:中央级公益性科研院所基本科研业务费专项，HSY201601号，HSY201404号；黑龙江省自然科学基金面上项目，C2016069号。 |
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| THE REGULATORY MECHANISM OF OVARY DIFFERENTIATION AND ABORTION OF TRIPLOID FEMALE RAINBOW TROUT ONCORHYNCHUS MYKISS |
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XU Ge-Feng1, MOU Zhen-Bo2, CHEN Huai-Fa3, HANG Tian-Qing4, WANG Bing-Qian1, GU Wei1, HU Guo1, HAN Ying4
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1.Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China;2.Tibet Academy of Agricultural and Animal Husbandry Sciences Institute of Fishery Sciences, Lasa 850032, China;3.Enhancement and Conservation Station of Aquatic Animal Resources of Heilongjiang Province, Harbin 150018, China;4.College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China
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| Abstract: |
| Although the genes of sex determination and differentiation of rainbow trout have been identified, such as cyp19a1a, foxl2, dmrt1, amh and sox9, specific gonadal morphology and regulatory mechanism of sex-specific genes of triploid female rainbow trout (RBT, Oncorhynchus mykiss), especially in the early developmental period, have not been fully studied, to which this research was carried out in association with histologic evidence and steroid hormone expression patterns during the development of somatic cells and germ cells. Results demonstrate that the ovary differentiation characteristics for diploid and triploid female rainbow trout were largely the same. The gonads of diploid and triploid female rainbow trout began to differentiate at 84dpf (days post fertilization) and 98dpf, respectively. However, there were obstacles in the differentiation of triploid female RBT gonads. The early development showed stagnation, the oogonium and follicle cells were scarce. For sex specific gene expression, both foxl2 and cyp19a1a expressed in ovary and testis of diploid RBT, and their expressions increased gradually in ovary, while the expression levels were very low in testis. The expression increased at first to the maximum at 274dpf and then decreased. The expressions of dmrt1, amh, and sox9 constantly intensified, due probably to the increase in serum T level. At 334dpf, T level was higher in diploid and triploid female serum and the three genes expressions showed a tendency of decrease in diploid RBT ovary. Therefore, a high-level estrogen could maintain fish ovary differentiation, which may be a conservative character in the evolutionary process of vertebrate. The ovary abortion of triploid female RBT could lead to gonadal dedifferentiation, which may inhibit the cyp19a1a expression and estradiol synthesis. The inhibition could generate a negative feedback loop after which the dedifferentiation could be strengthened. |
| Key words: rainbow trout Oncorhynchus mykiss triploid female pathway ovary differentiation |
