■在洞庭水系统中,Carassiusauratus(Cruciancarp)复合物的特征是二倍体形式(2n=100,2nCC)和多倍体形式共存。二倍体(2nCC)和三倍体C.auratus(3n=150,3nCC)具有相同的育性水平,在一年内达到性成熟。
■核苷酸序列,基因表达,甲基化,和促性腺激素释放激素2(Gnrh2)的免疫荧光,促性腺激素激素β(Gthβ),分析了下丘脑-垂体-性腺(HPG)轴的促性腺激素释放激素受体(Gthr)基因。
■分析结果表明,促卵泡激素受体(Fshr)Gnrh2,与2nCC相比,3nCC和致命杂种拯救(Lhr)基因增加了拷贝数和明显的结构分化。3nCC中HPG轴基因的转录水平高于2nCC(P<0.05),可以促进性激素的产生和分泌,有利于3nCC的性腺发育。同时,3nCC中HPG轴基因启动子区的DNA甲基化水平低于2nCC。这些结果表明,启动子区的甲基化对三倍体化后的基因表达具有潜在的调节作用。免疫荧光显示Fshβ的定位,Lhβ,3nCC和2nCC之间的Fshr基因保持不变,确保三倍体化后这些基因在相应位点的正常表达。
■相关研究结果为三倍体C.auratus的性腺发育和配子成熟等正常生殖活动提供了细胞和分子生物学证据,并有助于进一步了解三倍体C.auratus育性恢复的遗传基础。
In the Dongting water system, the Carassius auratus (Crucian carp) complex is characterized by the coexistence of diploid forms (2n=100, 2nCC) and polyploidy forms. The diploid (2nCC) and triploid C.auratus (3n=150, 3nCC) had the same fertility levels, reaching sexual maturity at one year.
The nucleotide sequence, gene expression, methylation, and
immunofluorescence of the gonadotropin releasing hormone 2(Gnrh2), Gonadotropin hormone beta(Gthβ), and Gonadotropin-releasing hormone receptor(Gthr) genes pivotal genes of the hypothalamic-pituitary-gonadal (HPG) axis were analyzed.
The analysis results indicated that Gnrh2, follicle-stimulating hormone receptor(Fshr), and Lethal hybrid rescue(Lhr) genes increased the copy number and distinct structural differentiation in 3nCC compared to that in 2nCC. The transcript levels of HPG axis genes in 3nCC were higher than 2nCC (P<0.05), which could promote the production and secretion of sex steroid hormones conducive to the gonadal development of 3nCC. Meanwhile, the DNA methylation levels in the promoter regions of the HPG axis genes were lower in 3nCC than in 2nCC. These results suggested that methylation of the promoter region had a potential regulatory effect on gene expression after triploidization.
Immunofluorescence showed that the localization of the Fshβ, Lhβ, and Fshr genes between 3nCC and 2nCC remained unchanged, ensuring the normal expression of these genes at the corresponding sites after triploidization.
Relevant research results provide cell and molecular biology evidence for normal reproductive activities such as gonad development and gamete maturation in triploid C. auratus, and contribute to further understanding of the genetic basis for fertility restoration in triploid C. auratus.