黄鳝卵巢初次发育成熟及相关基因表达分析

The initial ovarian development and the expression of some related genes in ricefield eel,Monopterus albus

为探讨黄鳝卵巢发育规律,观察了实验室养殖条件下黄鳝卵巢初次性成熟过程,采用定量PCR分析了gdf 9(growth differentiation factor 9)、cyp19a1a(P-450 aromatase)、amh(anti-Müllerian hormone)和amhrII(anti-Müllerian hormone type II receptor)基因表达水平。结果显示,4至9月龄黄鳝卵巢中卵母细胞处于初级生长期,胞质中嗜碱性巴尔比尼小体数量先增后减,形状由点变为大团块状,后又缩小。10月龄时,黄鳝卵巢青春期启动,进入次级生长期;部分卵母细胞出现皮质小泡,巴尔比尼小体消失或残存为点状。1龄时,卵巢中卵母细胞生发泡偏位或消失,达到成熟状态。卵巢中gdf 9表达水平在4至12月龄都较高,变化不明显;cyp19a1a、amh和amhrII表达变化趋势类似:从4月至7月龄上升,8月龄下降,10月龄又上升。研究表明,实验室养殖条件下,黄鳝卵巢10月龄左右启动青春期,1龄左右可达性成熟;cyp19a1a、amh和amhrII表达可能与卵巢青春期启动相关。

The initial ovarian development of ricefield eel Monopterus albus raised under laboratory conditions was investigated with histological analysis,and the expression of gdf 9（growth differentiation factor 9）,cyp19a1a（P-450 aromatase）,amh（anti-Müllerian hormone）and amhrII（anti-Müllerian hormone type II receptor）was analyzed with Real-time PCR assay.From the age of 4 months to 9 months,the oocytes in the ovary of juvenile ricefield eel remained in the primary growth stage,and the basophilic Balbiani＇s vitelline bodies（Bb）increased in number at the beginning,then decreased,and Bb＇s shape changed from dot at first to large cluster,then to small cluster.At the age of 10 months,the oocytes in the ovary of the juvenile ricefield eel entered the secondary growth stage,with the appearance of cortical alveoli in the cytoplasm and the differentiation of the somatic cells around the oocyte into granulosa and theca cells,and Bb either disappeared or degenerated to dot,indicating that the ovarian puberty of the juvenile ricefield eel was initiated.At the age of 12 months,the ovary of the ricefield eel was filled with late-vitellogenic oocytes containing migratory or disintegrated germinal vesicles,and reached maturity.The expression of gdf 9 was high and did not vary significantly from the age of 4 to 12 months,suggesting its indispensable roles in ovarian development during this period.The expression levels of amh,amhrII,and cyp19a1a increased in ricefield eels at the age of 4 to 7 months,but decreased at 8 months.However,the expression of these genes increased at the age of 10 months,coinciding with the initiation of puberty.Taken together,the results of present study indicated that juvenile ricefield eels initiated ovarian pubertal development at the age of ten months,and might reach ovarian maturation at the age of one year.The expression of amh,amhrII,and cyp19a1a might play important roles in the initiation of ovarian puberty.